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Comprehensive Summary: Long‐wavelength fluorescence carbon dots (CDs) show great importance in multiple fields, especially for the biochemical sensing. Here, we proposed one type of CDs doped with nitrogen and sulfur through the hydrothermal method, which exhibited obvious yellow‐fluorescence in aqueous solution. Importantly, the fluorescence intensity of CDs decreased with pH decreasing in the acidic range, thus a linear relationship between pH and fluorescence intensity was established, exhibiting the potential of pH sensing. Additionally, introducing tigecycline into CDs resulted in their decreased fluorescence, thus, we further established a strategy of detecting tigecycline with the concentration range of 200 μM to 7 nM. Meanwhile, we elucidated the static quenching as the major mechanism for CDs responding tigecycline, which was induced by the formed new complex between CDs and tigecycline. Furthermore, the practicality of the method was verified by examining the recovery of tigecycline in the actual lake‐water samples. [ABSTRACT FROM AUTHOR]

Acute myeloid leukemia (AML) is a highly lethal hematological malignancy in adults and children. Abnormal proliferation of leukemia stem cells (LSC) with CD34+ and CD38− phenotypes are the main clinical features of AML. Patients with AML face drug resistance and treatment failure due to a default in stem and progenitor cells. Therefore, defining LSC properties is necessary for targeting leukemia‐initiating cells. Mitochondrial mass and activity increase in AML initiating cells compared with normal stem cells. This idea has offered the inhibition of the mitochondrial translation machinery to reduce the number of leukemia‐initiating cells in patients with AML Tigecycline is an FDA‐approved microbial antibiotic that inhibits oxidative phosphorylation in mitochondria, resulting in the suppression of leukemia cell proliferation with little toxicity to normal cells. Thus, the present study was conducted to evaluate whether LSC is influenced by mitochondrial inhibition. We measured the IC50 of tigecycline in KG‐1a AML cell lines. KG‐1a AML cell lines were separated into CD34+ and CD34− cells by MACS. In the following, these cells were treated with 20 µM (IC50) tigecycline. The expression of Annexin/PI, Caspase 3, apoptotic genes (BCL2, BCLX, BAX, BAD, and P53) and proteins (P53, BAX, BCL2 and Caspase 9) was evaluated in CD34+, CD34− and KG‐1a AML cells. In addition, the telomere length and expression of hTERT were evaluated in this study. The results indicated that BCl2 (gene and protein) and BCLX gene dramatically decreased. In addition, BAD, BAX, and P53 gene and protein expression significantly increased in CD34+ AML cells compared to CD34− AML cells. The results also suggested that tigecycline induced intrinsic (Cleaved‐caspase 9/Pro‐Caspase 9 ratio) and p53‐mediated apoptosis. Furthermore, hTERT gene expression and telomere length decreased in the tigecycline‐treated groups. Taken together, our findings indicate that inhibition of mitochondrial activity with tigecycline can induce apoptosis in cancer stem cells and can be used as a novel method for cancer therapy. Significance statement: One of the main causes of treatment failure in patients with acute myeloid leukemia is the existence of cancer stem cells. Cancer stem cells have abundant mitochondria mass and high oxygen consumption compared with normal cells. Tigecycline suppresses leukemia cell proliferation by inhibiting oxidative metabolism. In this study, we have shown that the inhibition of mitochondrial activity by tigecycline affects cancer stem cells in comparison with other cells. [ABSTRACT FROM AUTHOR]

Aims: To analyse the clinical characteristics and risk factors for tigecycline‐induced pancreatitis (TIP) and evaluate the safety and efficiency of tigecycline use in non‐TIP. Methods: A retrospective case‐control study was conducted on adult and juvenile patients administered tigecycline for >3 days. The adults were classified as TIP, non‐TIP (pancreatitis with other causes) and non‐pancreatitis. Univariate analyses were performed to compare TIP and non‐pancreatitis, and multivariate analysis was used to identify risk factors for TIP. The clinical characteristics of TIP, and the safety and efficiency of tigecycline use in non‐TIP were evaluated. Results: A total of 3910 patients (3823 adults and 87 juveniles) were enrolled. The adult patients comprised 21 TIP, 82 non‐TIP and 3720 non‐pancreatitis. The TIP prevalence was 0.56% in adults and 1.15% in juveniles. The mean time from tigecycline use to symptom onset was 7.2 days, and all cases were mild pancreatitis. The mean time from tigecycline withdrawal to symptom relief was 3.6 days. The multivariate analysis identified comorbid renal insufficiency as an independent risk factor for TIP (odds ratio = 3.032). Among the 82 non‐TIP patients, 81.7% had severe pancreatitis and 47.6% had necrotizing pancreatitis. The modified computed tomography severity score after tigecycline use was similar to that before tigecycline use, but the pancreatic enzymes and infection indices were significantly decreased. Conclusions: The prevalence of TIP was low. Comorbid renal insufficiency was as an independent risk factor for TIP. Tigecycline is safe and efficient for treatment of pancreatitis, especially necrotizing pancreatitis, with intra‐abdominal infection. [ABSTRACT FROM AUTHOR]

Non‐tuberculous mycobacterial infections are gradually increasing worldwide, with slow‐growing mycobacteria such as Mycobacterium avium, Mycobacterium intracellulare and Mycobacterium kansasii accounting for the majority of cases. The use of tetracyclines has received renewed attention in recent years, and this study was designed to investigate the antibacterial activity of omadacycline, eravacycline, tigecycline, sarecycline, minocycline and doxycycline against M. avium, M. intracellulare and M. kansasii. Susceptibility testing of six tetracyclines was conducted against M. avium, M. intracellulare and M. kansasii isolates, and all the clinical isolates were collected from January 2012 to December 2018. All six agents exhibited poor antibacterial activity against slowly growing mycobacteria (SGM) isolates of three subspecies with MIC50 and MIC90 ≥8 μg/mL. M. intracellulare and M. kansasii had lower resistance rates to omadacycline than the other five drugs. The severe resistance of SGM to tetracycline suggests that developing tetracycline‐class antibiotics needs to overcome existing resistance mechanisms. [ABSTRACT FROM AUTHOR]

Rationale: An LC–MS/MS method was established to measure tigecycline in dried blood spots (DBSs). Methods: The DBS specimens obtained by applying 30 μl of blood to filter paper were extracted with hydrogen oxide and subsequently precipitated protein with perchloric acid, then the extract was directly analyzed by liquid chromatography tandem mass spectrometry. A Hypersil GOLD aQ column was utilized for separating the analytes, and detection was carried out in positive and selective reaction monitoring modes. The precursors to product ion transitions m/z 586.3 → 513.1 and m/z 586.3 → 569.2 were monitored for tigecycline, and m/z 473.2 → 456.0 and m/z 473.2 → 367.0 for 9‐amino minocycline as internal standard. Results: The validation parameters of specificity and selectivity, linearity (0.02–5 μg ml−1), sensitivity (limit of quantification 0.02 μg ml−1), intra‐ and interday precision (within 15%) and relative error (within ±15%) were acceptable. The recoveries were from 84.65% to 90.49% and from 85.41% to 95.72% for tigecycline and internal standard, respectively, and the matrix effect was not evident to influence accuracy. The impact of hematocrit on measurement of the analyte was negligible, and after preserving at ambient temperature for 24 h and at 4°C for 1 month it remained steady. Conclusions: The advantages of nonintrusive blood collection and micro‐volume sample requirements make DBS a potent surrogate to conventional venepuncture for sampling. [ABSTRACT FROM AUTHOR]

Background: Tigecycline is regarded as a last‐resort antimicrobial agent against multidrug resistance (MDR). However, resistance‐nodulation‐division efflux pump resistance genes, such as tmexCD3‐toprJ3, that confer resistance to tigecycline have emerged. Objectives: This study aimed to characterise the tmexCD3‐toprJ3 gene cluster in Pseudomonas juntendi and Proteus terrae isolated from a pig farm. Methods: Samples were obtained from a Chinese piggery and included 92 pig faecal samples, 56 wastewater samples, 23 drinking water samples, 28 sow vagina samples and nine sow uterus swabs. The presence of tmexCD3‐toprJ3 was detected using a polymerase chain reaction assay, and the antimicrobial susceptibility profile of the tmexCD3‐toprJ3‐positive isolates was determined using the broth dilution method. Genomic locations were identified using whole‐genome sequencing and bioinformatics. Results: We identified two tmexCD3‐toprJ3‐positive isolates, and both isolates were highly resistant to antibiotics such as tigecycline. In addition, we identified several mobile elements (ISPa7, ISCfr1, ISVsa3) and insertion sequences (TnAs2, TnAs3) in tmexCD3‐toprJ3‐positive isolates that could increase the potential for the spread of MDR. Conclusions: To the best of our knowledge, this study is the first to report the detection of tmexCD3‐toprJ3 in P. juntendi and P. terrae isolated from a pig farm. [ABSTRACT FROM AUTHOR]

Tigecycline is a broad‐spectrum antibacterial agent. As the incidence of multidrug‐resistant bacterial infections has increased in intensive care units (ICUs) over the past decades, tigecycline is often used in ICUs. Information about tigecycline‐associated hepatotoxicity in ICU patients is limited. To investigate the potential risk factors for tigecycline‐associated hepatotoxicity in ICU patients, 148 patients from 2 centers who had received tigecycline for at least 4 days were retrospectively analyzed. Hepatotoxicity was classified according to the National Cancer Institute Common Terminology Criteria for Adverse Events (5.0) grading system. As a result, 33.8% of patients experienced hepatotoxicity events in the ICU. The multivariate analysis showed that an albumin concentration <25 g/L at baseline (odds ratio, 3.714; 95%CI, 1.082‐12.744; P =.037) and treatment duration (odds ratio, 1.094; 95%CI, 1.032‐1.160; P =.003) were significantly correlated with tigecycline‐associated hepatotoxicity. The median time to onset of hepatotoxicity was 8.0 days. The median duration ICU stay and the in‐hospital mortality rate were not different between the hepatotoxicity group and the nonhepatotoxicity group (33.5 days (interquartile range, 21.0‐72.0) vs 31.0 days (interquartile range, 21‐62.5), P =.850; 38.0% vs 43.8%; P =.504). Therefore, close monitoring of liver function is recommended for patients with baseline albumin concentrations <25 g/L or for patients who receive tigecycline therapy for >8 days. [ABSTRACT FROM AUTHOR]

Summary: The transferability of bacterial resistance to tigecycline, the 'last‐resort' antibiotic, is an emerging challenge of global health concern. The plasmid‐borne tet(X) that encodes a flavin‐dependent monooxygenase represents a new mechanism for tigecycline resistance. Natural source for an ongoing family of Tet(X) resistance determinants is poorly understood. Here, we report the discovery of 26 new variants [tet(X18) to tet(X44)] from the poultry pathogen Riemerella anatipestifer, which expands extensively the current Tet(X) family. R. anatipestifer appears as a natural reservoir for tet(X), of which the chromosome harbours varied copies of tet(X) progenitors. Despite that an inactive ancestor rarely occurs, the action and mechanism of Tet(X2/4)‐P, a putative Tet(X) progenitor, was comprehensively characterized, giving an intermediate level of tigecycline resistance. The potential pattern of Tet(X) dissemination from ducks to other animals and humans was raised, in the viewpoint of ecological niches. Therefore, this finding defines a large pool of natural sources for Tet(X) tigecycline resistance, heightening the need of efficient approaches to manage the inter‐species transmission of tet(X) resistance determinants. [ABSTRACT FROM AUTHOR]

Summary: Tigecycline and colistin are few of 'last‐resort' antibiotic defences used in anti‐infection therapies against carbapenem‐resistant bacterial pathogens. The successive emergence of plasmid‐borne tet(X) tigecycline resistance mechanism and mobile colistin resistance (mcr) determinant, renders them clinically useless. Here, we report that co‐carriage of tet(X6) and mcr‐1 gives co‐resistance to both classes of antibiotics by a single plasmid in Escherichia coli. Tet(X6), the new tigecycline resistance enzyme is functionally defined. Both Tet(X6) and MCR‐1 robustly interfere accumulation of antibiotic‐induced reactive oxygen species (ROS). Unlike that mcr‐1 exerts fitness cost in E. coli, tet(X6) does not. In the tet(X6)‐positive strain that co‐harbors mcr‐1, tigecycline resistance is independently of colistin resistance caused by MCR‐1‐mediated lipid A remodelling, and vice versa. In general consistency with that of MCR‐1, Tet(X6) leads to the failure of tigecycline treatment in the infection model of G. mellonella. Taken together, the co‐production of Tet(X) and MCR‐1 appears as a major clinic/public health concern. [ABSTRACT FROM AUTHOR]

Tigecycline has been approved by the US (United States) Food and Drug Administration in a variety of complicated infections due to its broad‐spectrum antibiotic activity. Following phase III trials, the product label was revised and acute pancreatitis was listed as an adverse effect. Its safety profile in special groups such as renal transplant patients is not exactly known. We report the first case of unintentional rechallenge of tigecycline induced pancreatitis in a renal transplant patient. Ten days following the renal transplantation, a 35‐year‐old patient presented to the clinic with acute rejection. He received anti‐thymocyte globulin (ATG) and pulse steroid treatments for rejection. Following the treatment, he developed perianal cellulitis and tigecycline was started. Nine days following initiation of tigecycline he received thrombectomy for his incidental cardiac thrombus. One day after thrombectomy, he developed acute pancreatitis (AP). Thrombectomy was suspected to be the cause of AP. During hospitalization for transplant rejection, tigecycline was re‐started for a newly developed complicated abdominal infection. On the third day of the tigecycline re‐treatment, he developed a second episode of AP. Following tigecycline withdrawal, his symptoms resolved and serum pancreatic enzymes returned to normal, thus AP was ultimately attributed to tigecycline. This lethal side effect should be kept in mind while treating severe infections in renal transplant recipients. [ABSTRACT FROM AUTHOR]

Rationale: In order to characterize the intracellular pharmacokinetic properties of tigecycline, we developed and fully validated a liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for quantification of tigecycline in human lung epithelial (BEAS‐2B) cells and polymorphonuclear neutrophils (PMNs). Methods: Tetracycline was used as an internal standard and chromatographic separation was achieved on a C18 Hypersil Gold aQ column using two mobile phases, a solution of water (containing 0.1% formic acid) and acetonitrile. The flow rate was 0.4 mL/min for 5.0 min. Tigecycline drug uptake was evaluated by incubating the BEAS‐2B cells and the PMNs for up to 3 h at tigecycline concentrations of 1 mg/L. Results: The assay was linear over the tested concentration range of 0.01–2 mg/L for tigecycline in BEAS‐2B cells and PMNs (r2 >0.99). The inter‐ and inter‐day precisions (RSD, %) were <10.02% and the accuracies (%) were within the range of 85–115%. The uptake study showed that after incubation with tigecycline (1 mg/L) for 3 h at 37°C, the intracellular peak concentration of BEAS‐2B cells was 14.44 ± 7.12 mg/L at 1 h, and 41.43 ± 25.66 mg/L in PMNs at 20 min. The mean intracellular concentrations fluctuated in the range of 0.8–14.44 mg/L in BEAS‐2B cells and 10.14–41.43 mg/L in PMNs for 1 mg/L tigecycline exposure. Conclusions: Validated LC/MS/MS is a simple, rapid, and sensitive method for determining the intracellular concentration of tigecycline, and tigecycline has good penetrations both in human BEAS‐2B cells and PMNs. The method can be efficiently used for future studies of the intracellular pharmacokinetics of tigecycline. [ABSTRACT FROM AUTHOR]

Background: Tigecycline has been widely used to treat hospital‐acquired pneumonia (HAP) off‐label since it is effective against a wide range of multidrug‐resistant bacteria. However, no recommended dosage for this indication has been evaluated, resulting in possible inadequate treatment. Aims: The aims of this study are to establish the population pharmacokinetic (PPK) model of tigecycline in Chinese patients with HAP, as well as to evaluate the exposure‐response relationship for the treatment of HAP with multidrug‐resistant gram‐negative bacteria. Methods: A PPK analysis of tigecycline was conducted on pooled data from 328 blood samples obtained from 89 patients with HAP. Tigecycline plasma concentrations were measured by a two‐dimensional liquid chromatographic system and the data were analysed using Phoenix NLMETM software. Exposure‐response analyses for efficacy were performed based on the data from 79 HAP patients with multidrug‐resistant gram‐negative infections. Classification and regression tree and logistic regression analyses were employed to identify which pharmacokinetic‐pharmacodynamic (PK‐PD) indices and magnitudes were the significant predictors of tigecycline efficacy. Results: A two‐compartment model with zero‐order absorption and first‐order elimination adequately described the data. A larger body weight was associated with increased central volume of distribution and clearance (P <.005), and increased age, baseline creatinine concentration and aspertate aminotransferase were associated with decreased clearance (P <.005). The AUC0‐12h × V/MIC ratio, APACHEII score and combined Pseudomonas aeruginosa infection are the strong predictors for tigecycline clinical response. Classification and regression tree analyses indicated that the combination of APACHEII score < 24 and AUC0‐12h × V/MIC ratio ≥ 100 was associated with clinical success. Conclusions: The proposed PPK model may serve as the basis for estimating tigecycline exposure for PK‐PD analyses, and the PK‐PD index and magnitude found in this study could be used for designing proper dosage regimens of tigecycline. [ABSTRACT FROM AUTHOR]

Antibiotic resistance in bacteria has become a great threat to global public health. Tigecycline is a next‐generation tetracycline that is the final line of defense against severe infections by pan‐drug‐resistant bacterial pathogens. Unfortunately, this last‐resort antibiotic has been challenged by the recent emergence of the mobile Tet(X) orthologs that can confer high‐level tigecycline resistance. As it is reviewed here, these novel tetracycline destructases represent a growing threat to the next‐generation tetracyclines, and a basic framework for understanding the molecular epidemiology and resistance mechanisms of them is presented. However, further large‐scale epidemiological and functional studies are urgently needed to better understand the prevalence and dissemination of these newly discovered Tet(X) orthologs among Gram‐negative bacteria in both human and veterinary medicine. [ABSTRACT FROM AUTHOR]

Introduction: Tigecycline (TGC) is effective for the infections caused by carbapenem‐resistant gram‐negative bacteria (CRGNB) in adults, but it is not investigated systematically in children because of concern about adverse effects. This study aimed to analyze the effectiveness of TGC in treating CRGNB infections in children after receiving liver transplant. Methods: The subjects in this retrospective study were pediatric liver transplant recipients treated with TGC for at least 3 days to fight microbiologically verified CRGNB infection after initial antibiotic failure during the period from January 2014 to May 2018. Clinical and microbiological outcomes were reviewed to evaluate the efficacy and safety of TGC. Results: Of the 1177 pediatric liver transplant recipients, 13 patients were eligible for inclusion in this analysis. All the patients received TGC at dose of 2 mg/kg every 12 hours for a duration of 10.1 ± 5.1 days on average to treat CRGNB infections, including complicated intra‐abdominal infection, ventilator‐associated pneumonia, and bloodstream infection. The isolates included Klebsiella pneumoniae (69.2%, 9/13) and Acinetobacter baumannii (30.8%, 4/13). Clinical efficacy was achieved in 84.6% (11/13) and pathogen eradicated in 69.2% (9/13) of the patients. The overall mortality rate was 15.4% (2/13). No TGC‐related serious adverse event was reported. Conclusion: Tigecycline can be considered in combination antimicrobial regimen for treating CRGNB‐related infections in pediatric liver transplant recipients. [ABSTRACT FROM AUTHOR]

The role of mitochondria in cancer and mitochondria‐targeted therapy has been gaining attention for its effectiveness and selectivity between cancer and normal cells. In line with this notion, our work demonstrates that inducing mitochondrial dysfunction by tigecycline, a FDA‐approved antibiotic, selectively targets thyroid cancer and enhances chemosensitivity. We found that tigecycline inhibited proliferation and induced apoptosis in a panel of thyroid cancer cell lines. Consistently, tigecycline inhibited thyroid cancer growth in mice without causing significant toxicity. The combination of tigecycline with paclitaxel achieved greater efficacy than paclitaxel alone in vitro and in vivo. Mechanistically, tigecycline inhibited mitochondrial respiration and ATP reduction through decreasing mitochondrial membrane potential and inhibiting mitochondrial translation, leading to oxidative stress and damage. In contrast, tigecycline was ineffective in mitochondrial respiration‐deficient cells, confirming that tigecycline acts on thyroid cancer via inhibiting mitochondrial respiration. Interestingly, although tigecycline inhibited mitochondrial respiration in both thyroid cancer and normal thyroid cells in a similar manner, tigecycline was more effective in thyroid cancer than normal thyroid cells, suggesting that thyroid cancer cells are more dependent on mitochondrial functions than normal thyroid cells. This was supported by our observations that thyroid cancer cells had higher level of mitochondrial biogenesis compared to normal thyroid cells. Our work is the first to demonstrate that the combination of chemotherapy with tigecycline is a potential sensitizing strategy for thyroid cancer treatment. Our findings also highlight the higher dependence of thyroid cancer cells on mitochondrial functions than normal thyroid cells. [ABSTRACT FROM AUTHOR]

Summary: The rearrangement of immunoglobulin loci during the germinal center reaction is associated with an increased risk of chromosomal translocations that activate oncogenes such as MYC, BCL2 or BCL6, thus contributing to the development of B‐cell lymphomas. MYC and BCL2 activation are initiating events in Burkitt's (BL) and Follicular Lymphoma (FL), respectively, but can occur at later stages in other subtypes such as Diffuse Large‐B Cell Lymphoma (DLBCL). MYC can also be activated during the progression of FL to the transformed stage. Thus, either DLBCL or FL can give rise to aggressive double‐hit lymphomas (DHL) with concurrent activation of MYC and BCL2. Research over the last three decades has improved our understanding of the functions of these oncogenes and the basis for their cooperative action in lymphomagenesis. MYC, in particular, is a transcription factor that contributes to cell activation, growth and proliferation, while concomitantly sensitizing cells to apoptosis, the latter being blocked by BCL2. Here, we review our current knowledge about the role of MYC in germinal center B‐cells and lymphomas, discuss MYC‐induced dependencies that can sensitize cancer cells to select pharmacological inhibitors, and illustrate their therapeutic potential in aggressive lymphomas—and in particular in DHL, in combination with BCL2 inhibitors. [ABSTRACT FROM AUTHOR]

Abstract: Background: Tigecycline is a third‐line therapy for severe Clostridium difficile infection (CDI) in Australasian guidelines. Differences in strain types make it difficult to extrapolate international tigecycline efficacy data with combination or monotherapy to Australian practice, where experience is limited. Aim: To evaluate the efficacy and adverse effects associated with tigecycline combination therapy for severe and severe‐complicated CDI in an Australian healthcare setting. Methods: This was a retrospective observational study at a metropolitan university‐affiliated hospital. All patients between February 2013 and October 2016 treated with adjunctive intravenous tigecycline for >48 h for severe or severe‐complicated CDI were included. Tigecycline was given in addition to oral vancomycin ± intravenous metronidazole. The primary outcome was all‐cause mortality at 30 days from start of tigecycline combination therapy. Secondary outcomes included clinical cure, colectomy, adverse events and recurrence rates. Results: Thirteen patients with median age of 61 years had severe (n = 9) or severe‐complicated (n = 4) CDI at tigecycline commencement. In 92% of patients, tigecycline started within 48 h after in‐hospital CDI treatment, for median duration of 9 days. All‐cause mortality at 30 days was 8% with no mortality in severe CDI and 25% (1/4) in patients with severe‐complicated fulminant CDI, comparing favourably with historical rates of 9–38% and 30–80% in similar respective groups. Clinical cure was achieved in 77% of cases. There were no colectomies and one attributable tigecycline adverse reaction. Conclusions: Tigecycline appears safe and effective as a part of combination therapy in severe CDI, and may be given earlier and for shorter durations than in current guidelines. [ABSTRACT FROM AUTHOR]

The aim of this research had been to determine the pharmacokinetics of tigecycline ( TIG) in turkey after intravenous (i.v.), intramuscular (i.m.), subcutaneous (s.c.), and oral (p.o.) administration at a dose of 10 mg/kg. TIG concentrations in plasma were determined using high-performance liquid chromatography with tandem mass spectrometry. Mean concentrations of TIG in turkey plasma in the i.v. group were significantly higher than concentrations of this drug obtained after using the other administration routes. No significant differences were demonstrated in respect to the concentrations achieved after i.m. and s.c. administration. The bioavailability of TIG after i.m., s.c., and p.o. administration was 32.59 ± 5.99%, 34.91 ± 9.62%, and 0.97 ± 0.57%, respectively. Values of half-life in the elimination phase were 23.49 ± 6.51 hr, 25.42 ± 4.42 hr, and 26.62 ± 5.19 hr in i.v., i.m., and s.c. groups, respectively, values of mean residence time were 7.92 ± 1.41 hr, 19.62 ± 2.82 hr, and 17.55 ± 2.59 hr in i.v., i.m., and s.c. groups, respectively, whereas the volume of distribution was 14.85 ± 5.71 L/kg, 14.68 ± 2.56 L/kg, and 15.37 ± 3.00 L/kg in i.v., i.m., and s.c. groups, respectively. Because TIG is not absorbed from the gastrointestinal tract in turkeys to a clinically significant degree, this drug given p.o. could find application in commercial turkey farms only to treat gastrointestinal tract infections. [ABSTRACT FROM AUTHOR]

Zebrafish ( Danio rerio) are a popular model organism used in a growing number of research fields. Maintaining healthy, disease-free laboratory fish is important for the integrity of many of these studies. Mycobacteriosis is a chronic bacterial infection caused by several Mycobacterium spp. and is the second most common disease found in laboratory zebrafish. Current mycobacteriosis control measures recommend the removal of infected fish and in severe outbreaks, depopulation. These measures can be effective, but less disruptive measures should be assessed for controlling mycobacteriosis, particularly when valuable and rare lines of fish are affected. Here, the in vivo efficacy of two drug candidates, tigecycline (1 μg g−1) and clarithromycin (4 μg g−1), was tested in adult zebrafish experimentally infected with Mycobacterium chelonae. We assessed both short (14 day)- and long-term (30 day) treatments and evaluated fecundity and pathological endpoints. Fecundity and histology results show that zebrafish tolerated antibiotics. Antibiotic treatments did not significantly impact the prevalence of acid-fast granulomas; however, the severity of infections (acid-fast granuloma intensity) was significantly decreased following treatments. [ABSTRACT FROM AUTHOR]

Neutropenic enterocolitis ( NEC) is an abdominal infection reported primarily in patients with acute myeloid leukemia ( AML) following chemotherapy, especially cytarabine, a notable efficacious cytotoxic agent for AML remission. Specific data regarding the impact of different cytarabine schedules and/or antibacterial regimens for NEC are sparse. The aim of the study was to identify the predictors of outcome within 30 days of NEC onset. NEC episodes were retrospectively pinpointed among 440 patients with newly diagnosed AML hospitalized in our Institution, over a 10-year period, for receiving chemotherapy protocols with 100-6000 mg/m2 daily of cytarabine. Two subgroups, survivors versus nonsurvivors, were compared by using logistic regression analysis. NEC was documented in 100 of 420 (23.8%) analyzed patients: 42.5% had received high-dose cytarabine, whereas 19% and 15% intermediate-dose and standard-dose cytarabine, respectively ( P < 0.001). The 30-day NEC attributable mortality rate was 23%. In univariate analysis, antileukemic protocols containing robust dosages of cytarabine were significantly associated with high mortality ( P < 0.001); whereas, standard-dose cytarabine and prompt initiation (at the ultrasonographic appearance of intestinal mural thickening) of NEC therapy with antibiotic combinations including tigecycline were significantly associated with low mortality. In multivariate analysis, high-dose cytarabine-containing chemotherapy was the independent predictor of poor outcome (odds ratio [ OR]: 0.109; 95% confidence interval [ CI]: 0.032-0.364; P < 0.001), whereas ultrasonography-driven NEC therapy with antibiotic regimens including tigecycline was associated with a favorable outcome ( OR: 13.161; 95% CI: 1.587-109.17; P = 0.017). Chemotherapy schedules with robust dosages of cytarabine for AML remission are associated with a high rate of NEC incidence and attributable. Vigorous antibacterial therapy, triggered off pathologic ultrasonographic findings, with drug combinations which have broad antimicrobial coverage and good gut penetration, specifically those also including tigecycline, may be effective in improving 30-day survival rate after NEC onset. [ABSTRACT FROM AUTHOR]

Enterococcus species are the second most common cause of nosocomial infections in the United States and are particularly concerning in critically ill patients with preexisting comorbid conditions. Rising resistance to antimicrobials that were historically used as front-line agents for treatment of enterococcal infections, such as ampicillin, vancomycin, and aminoglycosides, further complicates the treatment of these infections. Of particular concern are Enterococcus faecium strains that are associated with the highest rate of vancomycin resistance. The introduction of antimicrobial agents with specific activity against vancomycin-resistant Enterococcus ( VRE) faecium including daptomycin, linezolid, quinupristin-dalfopristin, and tigecycline did not completely resolve this clinical dilemma. In this review, the mechanisms of action and resistance to currently available anti- VRE antimicrobial agents including newer agents such as oritavancin and dalbavancin will be presented. In addition, novel combination therapies including β-lactams and fosfomycin, and the promising results from in vitro , animal studies, and clinical experience in the treatment of VRE faecium will be discussed. [ABSTRACT FROM AUTHOR]

Background The chronic intermittent ethanol ( CIE) paradigm is valuable for screening compounds for efficacy to reduce drinking traits related to alcohol use disorder ( AUD), as it measures alcohol consumption and preference under physical dependence conditions. Air control-treated animals allow simultaneous testing of similarly treated, nondependent animals. As a consequence, we used CIE to test the hypothesis that tigecycline, a semisynthetic tetracycline similar to minocycline and doxycycline, would reduce alcohol consumption regardless of dependence status. Methods Adult C57 BL/6J female and male mice were tested for tigecycline efficacy to reduce ethanol (EtOH) consumption using a standard CIE paradigm. The ability of tigecycline to decrease 2-bottle choice of 15% EtOH (15E) versus water intake in dependent ( CIE vapor) and nondependent (air-treated) male and female mice was tested after 4 cycles of CIE vapor or air exposure using a within-subjects design and a dose-response. Drug doses of 0, 40, 60, 80, and 100 mg/kg in saline were administered intraperitoneally (0.01 ml/g body weight) and in random order, with a 1-hour pretreatment time. Baseline 15E intake was re-established prior to administration of subsequent injections, with a maximum of 2 drug injections tested per week. Results Tigecycline was found to effectively reduce high alcohol consumption in both dependent and nondependent female and male mice. Conclusions Our data suggest that tigecycline may be a promising drug with novel pharmacotherapeutic characteristics for the treatment of mild-to-severe AUD in both sexes. [ABSTRACT FROM AUTHOR]

Background Physicians have long reported that patients with chronic pain show higher tendencies for alcohol use disorder ( AUD), and AUD patients appear to have higher pain sensitivities. The goal of this study was to test 2 hypotheses: (i) binge alcohol consumption increases inflammatory pain and mechanical and cold sensitivities; and (ii) tigecycline is an effective treatment for alcohol-mediated-increased pain behaviors and sensitivities. Both female and male mice were used to test the additional hypothesis that important sex differences in the ethanol (EtOH)-related traits would be seen. Methods 'Drinking in the Dark' ( DID) alcohol consuming and nondrinking control, female and male, adult C57 BL/6J mice were evaluated for inflammatory pain behaviors and for the presence of mechanical and cold sensitivities. Inflammatory pain was produced by intraplantar injection of formalin (10 μl, 2.5% in saline). For cold sensation, a 20 μl acetone drop was used. Mechanical withdrawal threshold was measured by an electronic von Frey anesthesiometer. Efficacy of tigecycline (80 mg/kg i.p.) to reduce DID-related pain responses and sensitivity was tested. Results DID EtOH consumption increased inflammatory pain behavior, while it also produced sustained mechanical and cold sensitivities in both females and males. Tigecycline produced antinociceptive effects in males; a pro-nociceptive effect was seen in females in the formalin test. Likewise, the drug reduced both mechanical and cold sensitivities in males, but females showed an increase in sensitivity in both tests. Conclusions Our results demonstrated that binge drinking increases pain, touch, and thermal sensations in both sexes. In addition, we have identified sex-specific effects of tigecycline on inflammatory pain, as well as mechanical and cold sensitivities. The development of tigecycline as an AUD pharmacotherapy may need consideration of its pro-nociceptive action in females. Further studies are needed to investigate the mechanism underlying the sex-specific differences in nociception. [ABSTRACT FROM AUTHOR]

Background New pharmacotherapies to treat alcohol use disorders ( AUD) are needed. Given the complex nature of AUD, there likely exist multiple novel drug targets. We, and others, have shown that the tetracycline drugs, minocycline and doxycycline, reduced ethanol (EtOH) drinking in mice. To test the hypothesis that suppression of high EtOH consumption is a general property of tetracyclines, we screened several derivatives for antidrinking activity using the Drinking-In-the-Dark ( DID) paradigm. Active drugs were studied further using the dose-response relationship. Methods Adult female and male C57 BL/6J mice were singly housed and the DID paradigm was performed using 20% EtOH over a 4-day period. Mice were administered a tetracycline or its vehicle 20 hours prior to drinking. Water and EtOH consumption was measured daily. Body weight was measured at the start of drug injections and after the final day of the experiment. Blood was collected for EtOH content measurement immediately following the final bout of drinking. Results Seven tetracyclines were tested at a 50 mg/kg dose. Only minocycline and tigecycline significantly reduced EtOH drinking, and doxycycline showed a strong effect size trend toward reduced drinking. Subsequent studies with these 3 drugs revealed a dose-dependent decrease in EtOH consumption for both female and male mice, with sex differences in efficacy. Minocycline and doxycycline reduced water intake at higher doses, although to a lesser degree than their effects on EtOH drinking. Tigecycline did not negatively affect water intake. The rank order of potency for reduction in EtOH consumption was minocycline > doxycycline > tigecycline, indicating efficacy was not strictly related to their partition coefficients or distribution constants. Conclusions Due to its effectiveness in reducing high EtOH consumption coupled without an effect on water intake, tigecycline was found to be the most promising lead tetracycline compound for further study toward the development of a new pharmacotherapy for the treatment of AUD. [ABSTRACT FROM AUTHOR]

Background Alcohol use disorder ( AUD) is a spectrum disorder characterized by mild to severe symptoms, including potential withdrawal signs upon cessation of consumption. Approximately five hundred thousand patients with AUD undergo clinically relevant episodes of withdrawal annually ( New Engl J Med, 2003, 348, 1786). Recent evidence indicates potential for drugs that alter neuroimmune pathways as new AUD therapies. We have previously shown the immunomodulatory drugs, minocycline and tigecycline, were effective in reducing ethanol (EtOH) consumption in both the 2-bottle choice and drinking-in-the-dark paradigms. Here, we test the hypothesis that tigecycline, a tetracycline derivative, will reduce the severity of EtOH withdrawal symptoms in a common acute model of alcohol withdrawal ( AWD) using a single anesthetic dose of EtOH in seizure sensitive DBA/2J ( DBA) mice. Methods Naïve adult female and male DBA mice were given separate injections of 4 g/kg i.p. EtOH with vehicle or tigecycline (0, 20, 40, or 80 mg/kg i.p.). The 80 mg/kg dose was tested at 3 time points (0, 4, and 7 hours) post EtOH treatment. Handling-induced convulsions ( HICs) were measured before and then over 12 hours following EtOH injection. HIC scores and areas under the curve were tabulated. In separate mice, blood EtOH concentrations ( BECs) were measured at 2, 4, and 7 hours postinjection of 4 g/kg i.p. EtOH in mice treated with 0 and 80 mg/kg i.p. tigecycline. Results AWD symptom onset, peak magnitude, and overall HIC severity were reduced by tigecycline drug treatment compared to controls. Tigecycline treatment was effective regardless of timing throughout AWD, with earlier treatment showing greater efficacy. Tigecycline showed a dose-responsive reduction in acute AWD convulsions, with no sex differences in efficacy. Importantly, tigecycline did not affect BECs over a time course of elimination. Conclusions Tigecycline effectively reduced AWD symptoms in DBA mice at all times and dosages tested, making it a promising lead compound for development of a novel pharmacotherapy for AWD. Further studies are needed to determine the mechanism of tigecycline action. [ABSTRACT FROM AUTHOR]

Acute myeloid leukemia ( AML) cells meet the higher energy, metabolic, and signaling demands of the cell by increasing mitochondrial biogenesis and mitochondrial protein translation. Blocking mitochondrial protein synthesis through genetic and chemical approaches kills human AML cells at all stages of development in vitro and in vivo. Tigecycline is an antimicrobial that we found inhibits mitochondrial protein synthesis in AML cells. Therefore, we conducted a phase 1 dose-escalation study of tigecycline administered intravenously daily 5 of 7 days for 2 weeks to patients with AML. A total of 27 adult patients with relapsed and refractory AML were enrolled in this study with 42 cycles being administered over seven dose levels (50-350 mg/day). Two patients experienced DLTs related to tigecycline at the 350 mg/day level resulting in a maximal tolerated dose of tigecycline of 300 mg as a once daily infusion. Pharmacokinetic experiments showed that tigecycline had a markedly shorter half-life in these patients than reported for noncancer patients. No significant pharmacodynamic changes or clinical responses were observed. Thus, we have defined the safety of once daily tigecycline in patients with refractory AML. Future studies should focus on schedules of the drug that permit more sustained target inhibition. [ABSTRACT FROM AUTHOR]

Aim: This study assessed the efficacy and safety of tigecycline in children with life-threatening infections.Methods: We retrospectively reviewed the clinical records of patients treated with tigecycline from June 2012 to May 2014 in a Chinese tertiary centre.Results: The study comprised 24 patients (14 male) with a median age of four years (range, 50 days-12 years). The most frequently isolated microorganism, most common isolation site and type of infection were Acinetobacter baumannii, tracheal aspirate fluid and ventilator-associated pneumonia, respectively. Tigecycline was administered at a loading dose of 1.5 or 2.0 mg/kg and 1.0 mg/kg every 12 hours after that. The average duration of treatment was 11.6 ± 5.8 days. The clinical response and microbiological eradication rate were 37.5% and 29.2%, respectively. Six of the patients we studied (25.0%) died, and three of these deaths were considered to be infection related. Adverse drug reactions were identified in four patients (16.7%) during the treatment, including abnormal liver function, prolonged prothrombin time and diarrhoea.Conclusion: Our findings suggest that tigecycline may be an option for children with severe infections. However, more prospective, controlled trials are required to objectively evaluate the efficacy and safety of tigecycline in children. [ABSTRACT FROM AUTHOR]

Nonsmall cell lung cancer ( NSCLC) is the most common type of lung cancer with a high mortality rate and still remains therapeutically a challenge. A strategy to target NSCLC is to identify agents that are effective against NSCLC cells while sparing normal cells. We show that tigecycline, an FDA-approved antibiotic drug, preferentially targets NSCLC cells. Tigecycline is effective in inhibiting proliferation and inducing apoptosis of multiple cell lines derived from two common NSCLC subtypes: adenocarcinoma and squamous cell carcinoma. Tigecycline also dose-dependently inhibits colony formation of NSCLC subpopulation of cells with highly proliferative and invasive properties. Compared to NSCLC cells, tigecycline affects proliferation and survival of normal fibroblast cells significantly to a less extent. More importantly, tigecycline significantly inhibits NSCLC tumor growth through decreasing proliferation and increasing apoptosis of tumor cells in vivo. Tigecycline significantly inhibits mitochondrial respiration, mitochondrial membrane potential, and ATP levels and increases reactive oxygen species ( ROS), suggesting that tigecycline impairs mitochondrial functions. Our study suggests that tigecycline may be a useful therapeutic agent, and inhibiting mitochondrial functions may represent a new targeted therapy for NSCLC. [ABSTRACT FROM AUTHOR]

Objective To explore whether antibacterial drug tigecycline could exert an antitumoral effect in oral squamous cell carcinoma ( OSCC). Materials and Methods Two OSCC cell lines Tca8113 and KB were used in this study. To investigate the cytostatic effects of tigecycline in OSCC, cell growth was tested by trypan blue staining, MTT assay, and Brdu immunofluorescence staining. Then, the apoptosis proportion was measured by FITC Annexin-V and PI labeling, and cell cycle was determined by PI staining. The expression of caspase 3 ( CASP3) and cell cycle regulatory protein was detected by Western blot assay. Finally, the clonogenesis and tumorigenesis capacity were analyzed by soft agar growth and xenograft model. Results Here, we showed that tigecycline significantly inhibited cell growth and proliferation in OSCC cell lines Tca8113 and KB. It did not induce cell apoptosis but led to an increase of cells in G0/G1 phase with down-regulation of cyclin E2 ( CCNE2) and cyclin-dependent kinase4 ( CDK4) protein expression. We also showed that tigecycline inhibited colony formation in soft agar and reduced tumor growth in a xenograft model. Conclusion Our results suggested that tigecycline might be used as a novel candidate agent for the treatment of OSCC. [ABSTRACT FROM AUTHOR]

The susceptibilities of 824 Bacteroides fragilis group isolates against nine antibiotics were evaluated in a Europe-wide study involving 13 countries. Species determination, by different methods, was carried out on all but one isolate. Resistance rates were evaluated according to species and geographical areas via CLSI and the European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints. The present data were compared with those obtained 10 and 20 years ago at a European level. High-level resistance (MIC ≥64 mg/L) to ampicillin was observed in 44.5% of the strains, which is a significant increase relative to 20 years ago (16%). Piperacillin/ tazobactam was more active than amoxicillin/clavulanic acid (3.1% and 10.4% resistance, respectively), again with a resistance increase relative to earlier studies. Dramatic increases in resistance were observed for cefoxitin, clindamycin and moxifloxacin, with rates of 17.2%, 32.4% and 13.6%, respectively. The lowest resistances were found for imipenem, metronidazole and tigecycline (1.2%, <1% and 1.7%). Nonsusceptible strains to imipenem and metronidazole were more resistant to other anti-anaerobic drugs. Differences were detected between geographical areas, with higher resistance rates for moxifloxacin in Scandinavian countries (21.4%) than in Mediterranean countries (5.4%), whereas, for clindamycin, the resistance rates were higher in Mediterranean (41.8%) and lower in Scandinavian countries (22.5%). Piperacillin/tazobactam resistance was also higher in Scandinavian countries. [ABSTRACT FROM AUTHOR]

Tigecycline, a novel intravenously administered glycylcycline antibiotic, currently plays a key role in the management of complicated multiorganism infections. However, current liquid chromatography with tandem mass spectrometry methods briefly describe parameters and the only reported internal standard was sometimes difficult to obtain. In our study, an updated liquid chromatography with tandem mass spectrometry method for the quantitative analysis of tigecycline in human serum was developed. Sample preparation involved precipitation with 20% trichloroacetic acid. Chromatographic separation of tigecycline and tetracycline (internal standard) was achieved on a Hypersil GOLD C18 column using gradient elution. The selected reaction monitoring transitions were performed at m/ z 586.1→513.2 for tigecycline and m/ z 445.1→410.2 for tetracycline. The assay was linear over the concentration range of 5-2000 ng/mL. The intra- and interday precisions at three concentration levels (10, 100, and 1600 ng/mL) were <15% and their accuracies were within the range of 95.1-106.1%. The mean recovery ranged from 94.3 to 105.6% and the matrix effect from 92.1 to 97.6%. Tigecycline was stable under all tested conditions. This validated method was successfully applied to a pharmacokinetic study in critically ill patients. The data demonstrated that our method allows quantification of tigecycline in serum in a quick and reliable manner for widespread application. [ABSTRACT FROM AUTHOR]

Safety, tolerability, and pharmacokinetics of tigecycline in 76 healthy Japanese subjects were determined in three randomized, double-blind, placebo-controlled studies. Subjects in an ascending single-dose study (n = 40) received 25-150 mg intravenously, whereas subjects in two multiple-dose studies received every 12-hour (q12h) dosing with 25 mg (n = 10) or 25, 50, or 100 then 50 mg (n = 30). Serial blood samples and urine were collected, drug concentrations determined, and pharmacokinetic parameters calculated. Fecal samples were also collected in the second multiple-dose study. After 10 days of tigecycline 50 mg q12h, mean ± standard deviation pharmacokinetics in 8/10 subjects were: maximum concentration 1,118 ± 127 ng/mL, area under the concentration-time curve 0-12 hours 3,261 ± 937 ng h/mL, clearance 0.25 ± 0.05 L/h/kg, half-life 60.7 ± 23.4 hours, and volume of distribution 11.9 ± 2.3 L/kg. The most common adverse events were nausea and vomiting. Changes in total bilirubin were also observed. Enterococci in the intestinal microflora were reduced, whereas the number of Enterobacteriaceae and Bacteroides remained relatively constant. Several strains of Bacteroides spp. resistant to tigecycline treatment were found in fecal samples on days 30 and 31. The pharmacokinetic profile of tigecycline was similar to non-Japanese subjects; tolerability and change in intestinal microflora were also similar. [ABSTRACT FROM AUTHOR]

The goal of the this study was to re-evaluate tigecycline bone concentrations in subjects undergoing elective orthopedic surgery, using multiple doses and a more robust bone assay than was used in a previous study. Each subject received three intravenous doses of tigecycline (one 100-mg infusion followed by two 50-mg infusions, each administered over 30 minutes). A single bone sample was collected from each subject at one of the following times: 1, 2, 4, 6, 8, or 12 hours after the third dose. Four blood samples were collected from each subject: before the first dose, before and after the third dose, and within 15 minutes of the collection time of the bone sample. Noncompartmental pharmacokinetic analysis serum and bone area under the curve for the given dose interval (AUCτ) values were 2,402 ng h/mL and 11,465 ng h/g, and maximum concentration (Cmax) values were 974 ng/mL and 2,262 ng/g, respectively. The bone to serum ratio calculated using the AUCτ values was 4.77, confirming tigecycline penetration into bone. [ABSTRACT FROM AUTHOR]

Brucellosis is one of the most common systemic zoonotic diseases transmitted by consumption of unpasteurized dairy products or by occupational contact with infected animals. Brucellosis is rare in renal transplant recipients. Only 3 cases have been reported in the literature. We report a case of brucellosis with hematologic and hepatobiliary complications in a patient 3 years after renal transplantation. The mean time from transplantation to the diagnosis of brucellosis in these 4 reported patients was 5.1 years (range 17 months to 13 years). All patients had fever and constitutional symptoms, and all attained clinical cure after combination antibiotic therapy. Given the small number of patients, further study is needed to identify the characteristics of brucellosis in renal transplant recipients. Drug interactions and acute renal failure developed in our patient during antibiotic treatment. Therefore, we should monitor the levels of immunosuppressive agents frequently. Several studies have shown in vitro susceptibilities of Brucella melitensis to tigecycline. In our patient, fever finally subsided after tigecycline administration. The minimum inhibitory concentration of tigecycline using Etest was 0.094 μg/mL. Tigecycline may be a potential option for treatment of brucellosis in the setting of transplantation. [ABSTRACT FROM AUTHOR]

Expression of the aromatic hydroxylase TetX under aerobic conditions confers bacterial resistance against tetracycline antibiotics. Hydroxylation inactivates and degrades tetracyclines, preventing inhibition of the prokaryotic ribosome. X-ray crystal structure analyses of TetX in complex with the second-generation and third-generation tetracyclines minocycline and tigecycline at 2.18 and 2.30 Å resolution, respectively, explain why both clinically potent antibiotics are suitable substrates. Both tetracyclines bind in a large tunnel-shaped active site in close contact to the cofactor FAD, pre-oriented for regioselective hydroxylation to 11a-hydroxytetracyclines. The characteristic bulky 9- tert-butylglycylamido substituent of tigecycline is solvent-exposed and does not interfere with TetX binding. In the TetX-minocycline complex a second binding site for a minocycline dimer is observed close to the active-site entrance. The pocket is formed by the crystal packing arrangement on the surface of two neighbouring TetX monomers. Crystal structure analysis at 2.73 Å resolution of xenon-pressurized TetX identified two adjacent Xe-binding sites. These putative dioxygen-binding cavities are located in the substrate-binding domain next to the active site. Molecular-dynamics simulations were performed in order to characterize dioxygen-diffusion pathways to FADH2 at the active site. [ABSTRACT FROM AUTHOR]

Study Objective To provide clinicians with an understanding of the comparative occurrence of tigecycline and pancreatitis, and to provide any clinically relevant characteristics that may be useful in identifying the patients at risk. Design Retrospective cohort study. Data Source Spontaneous reports in the United States Food and Drug Administration (FDA) Adverse Event Reporting System ( AERS) database generated between January 1997 and December 2010. Patients Sixty-two patients who experienced pancreatitis while receiving tigecycline therapy. Measurements and Main Results Disproportionality analysis with Bayesian correction methodology was used to compare tigecycline with all other agents listed in the AERS. Disproportionality analysis uses an adverse event relative reporting ratio ( RRR) to compare the occurrence of a specific adverse event with an index drug of interest to the occurrence of the same adverse event with similar agents or with all other FDA-approved prescription drugs. The value was considered meaningful if the 5th percentile of the distribution of the RRR ( RRR05) was 2 or greater. Our review identified 62 potential cases of tigecyline-related pancreatitis. An RRR05 score of 10.4, 10.38, and 2.87 was determined for tigecycline-related pancreatitis compared with all other agents, systemic antibiotics, and select tetracyclines listed in the AERS, respectively. In addition, a sex-based RRR05 score was higher in women versus men (14.432 vs 3.125) when tigecycline was compared with all agents in the AERS. Conclusion Our analysis suggests a quantitative signal between tigecycline use and pancreatitis; however, given the limitations of our study, a cause-and-effect relationship cannot be inferred. Thus, additional rigorous scientific analyses are warranted to explore these findings. [ABSTRACT FROM AUTHOR]

The pharmacokinetic parameters of tigecycline were assessed in subjects with severe renal impairment (creatinine clearance <30 mL/min, n = 6), subjects receiving hemodialysis (4 received tigecycline before and 4 received tigecycline after hemodialysis), and subjects with age-adjusted, normal renal function (n = 6) after administration of single 100-mg doses. Serial serum and urine samples were collected and assayed using validated liquid chromatography with tandem mass spectrometer (LC/MS/MS) methods. Concentration-time data were then analyzed using noncompartmental pharmacokinetic methods. Tigecycline renal clearance in subjects with normal renal function represented approximately 20% of total systemic clearance. Tigecycline clearance was reduced by approximately 20%, and area under the tigecycline concentration-time curve increased by approximately 30% in subjects with severe renal impairment. Tigecycline was not efficiently removed by dialysis; thus, it can be administered without regard to timing of hemodialysis. Based on these pharmacokinetic data, tigecycline requires no dosage adjustment in patients with renal impairment. [ABSTRACT FROM PUBLISHER]

Since the discovery of penicillin 80 years ago, gram-negative bacteria have become proficient at evading the lethal activity of β-lactam antibiotics, principally through the production of β-lactamases. The rapid emergence of penicillinases in both gram-positive and gram-negative bacteria led to the development of cephalosporin β-lactam antibiotics, but production of plasmid-mediated extended-spectrum cephalosporinases (or extended-spectrum β-lactamases) and AmpC enzymes resulted in resistance to this drug class. Because carbapenems were the only β-lactam agents active against such extended-spectrum β-lactamase-producing strains, appropriate and inappropriate use soon resulted in Enterobacteriaceae resistance. As a result, two distinct types of carbapenemases-the metallo-β-lactamases and Klebsiella pneumoniae carbapenemases ( KPCs)-were soon identified. The KPCs comprise 10 variants that differ from one another by one to three amino acid substitutions ( KPC-2 to KPC-11). The KPC-producing Enterobacteriaceae are not only multidrug resistant but are also difficult to detect routinely in the clinical microbiology laboratory. Tigecycline, polymyxins (colistin and polymyxin B), and aminoglycosides are possible candidate therapies for infections caused by KPC-producing organisms, although well-conducted clinical trials are required to fully define their roles in patient management. The shortage of new antimicrobial agents on the immediate horizon suggests that enhanced adherence with infection prevention procedures and antimicrobial stewardship programs are needed to curb patient-to-patient transmission and to reduce the selection of multidrug-resistant bacteria. [ABSTRACT FROM AUTHOR]

Abstract: The flavin-dependent monooxygenase TetX confers resistance to all clinically relevant tetracyclines, including the recently approved, broad-spectrum antibiotic tigecycline (Tygacil®) which is a critical last-ditch defense against multidrug-resistant pathogens. TetX represents the first resistance mechanism against tigecycline, which circumvents both the tet-gene encoded resistances, relying on active efflux of tetracyclines, and ribosomal protection proteins. The alternative enzyme-based mechanism of TetX depends on regioselective hydroxylation of tetracycline antibiotics to 11a-hydroxy-tetracyclines. Here, we report the X-ray crystallographic structure determinations at 2.1Å resolution of native TetX from Bacteroides thetaiotaomicron and its complexes with tetracyclines. Our crystal structures explain the extremely versatile substrate diversity of the enzyme and provide a first step towards the rational design of novel tetracycline derivatives to counter TetX-based resistance prior to emerging clinical observations. [Copyright &y& Elsevier]

Tigecycline belongs to a new class of tetracyclines, the glycylcyclines, less than 20% of which is metabolized in the liver. Twenty-five patients with cirrhosis with varying degrees of functional hepatic reserve (Child-Pugh A, n = 10; B, n = 10; C, n = 5) and 23 healthy adults, matched by age, sex, weight, and smoking habits, received 100 mg of tigecycline infused intravenously over 60 minutes. Serum and urine samples were collected up to 120 hours after dosing. Pharmacokinetic data were derived using non-compartmental methods. The most common treatment-emergent adverse events in healthy volunteers were nausea (56.5%), vomiting (21.7%), and headache (21.7%) and in the patients with cirrhosis, albuminuria (12%). Mean (±1 SD) tigecycline clearance values were 29.8 ± 11.3 L/h in healthy subjects and 31.2 ± 13.9 L/h (Child-Pugh A), 22.1 ± 9.3 L/h (Child-Pugh B), and 13.5 ± 2.7 L/h (Child-Pugh C) in the patients. A single intravenous dose of tigecycline 100 mg was safe and well-tolerated in patients with cirrhosis with varying degrees of hepatic functional reserve. No adjustment of tigecycline maintenance dosage is warranted in patients with compensated or moderately decompensated cirrhosis; doses should be reduced by 50%, to 25 mg, every 12 hours in patients with severely decompensated disease. [ABSTRACT FROM PUBLISHER]

Mycobacterium abscessus is an ubiquitous organism found in the environment. This rapidly growing mycobacterium infrequently causes disease in humans; however, in immunocompromised hosts, disease can range from localized cutaneous lesions to disseminated infection. The organism is resistant to most antimycobacterial drugs and therapy can be limited by drug interactions. The exact incidence of M. abscessus infection among solid organ transplant (SOT) recipients is unknown; data are only available from previously reported cases in the literature. We describe 3 cases of M. abscessus infection in SOT recipients diagnosed within a 5-month period. One of the cases followed multi-visceral transplantation, the first such case to be reported in the literature. An epidemiological investigation did not reveal significant commonalities among the cases, and pulsed-field gel electrophoresis of genomic DNA of the case isolates confirmed their non-identity. All cases improved with antibiotic therapy, most notably with the new glycylcycline, tigecycline, along with surgical intervention in 2 of the cases. In addition, we review features and characteristics of M. abscessus infections in recipients of SOT reported in the literature from 1992 to 2008 and summarize some selected therapeutic concerns and issues related to treatment. [ABSTRACT FROM AUTHOR]

We present a case of progressive Mycobacterium chelonae ssp. chelonae necrotizing pneumonia after hematopoietic stem cell transplantation (HSCT) in the presence of chronic graft-versus-host disease. The patient failed to respond to standard combination therapy with multiple agents and developed resistance to most drugs over the course of treatment. Tigecycline, a new glycylcycline antimicrobial agent with in vitro activity against M. chelonae, was then used with a clinical response to treatment. To our knowledge, this is the first reported case demonstrating tigecycline to have a degree of clinical effectiveness to treat refractory pulmonary infection with M. chelonae in an HSCT recipient. [ABSTRACT FROM AUTHOR]

Study Objective. To evaluate the potential for a clinically significant drug interaction between tigecycline and warfarin by using pharmacokinetic and anticoagulant assessments. Design. Open-label, nonrandomized study. Setting. Inpatient clinical pharmacology unit. Subjects. Nineteen healthy male volunteers were enrolled; eight completed all study assessments. Intervention. All subjects received a single oral dose of warfarin 25 mg (day 1). Seven days later (day 8), they received a 100-rag loading dose of intravenous tigecycline, followed by 50 mg every 12 hours for eight additional doses. On day 12, they received another single oral dose of warfarin 25-mg with their last dose of tigecycline. Measurements and Main Results. Serum tigecycline and plasma R- and Swarfarin concentrations were determined by high-performance liquid , chromatography with tandem mass spectroscopy. Pharmacokinetic parameters were calculated by using noncompartmental methods and analyzed by the two 1-sided tests equivalence procedure. Pharmacodynamic analyses were based on anticoagulant parameters derived from international normalized ratios of prothrombin times. Tigecycline peak concentration, trough concentration, area under the concentration-time curve (AUC) from 0-12 hrs, and clearance were not affected by single-dose warfarin. In contrast, R- and S-warfarin AUC from time zero extrapolated to infinity was increased by 68% and 29%, respectively, and clearance was decreased by 40% and 23%, respectively, when warfarin was administered after eight doses of tigecycline. Nevertheless, tigecycline did not alter the anticoagulant effects of warfarin, which is consistent with a mechanism based only on increased warfarin protein binding. Conclusion. These results suggest that a dosage adjustment of either drug is not necessary during coadministration of tigecycline and warfarin. However, consistent with good medical practice, the anticoagulant activity of warfarin should be monitored during coadministration with tigecycline. [ABSTRACT FROM AUTHOR]

Adult male Crl:CD1 (ICR) BR mice were fed chow containing Candida albicans or regular chow. Both groups were subsequently given tigecycline or daptomycin or normal saline subcutaneously for 10 days. To determine the effect on the stool yeast concentration, stool cultures were performed immediately before, at the end, and 1 week after discontinuation of treatment. Candida-colonized mice treated with tigecycline or daptomycin had higher counts of the yeast in their stools than control C. albicans-colonized animals treated with saline. Tigecycline caused a significant increase of 2.1 log10 CFU g−1 of stools in C. albicans concentration, while daptomycin caused a minor increase of 0.4 log10 CFU g−1 of stools. Mice fed regular chow and treated with the study antibiotics or saline did not have any Candida in their stools. Dissemination of Candida was not detected in any animal. These data suggest that tigecycline induces a substantial increase in the intestinal concentration of C. albicans, while daptomycin causes only a minimal increase. However, these increases are not associated with dissemination of the yeast to internal organs. Clinical studies in humans are needed to validate our findings, especially in patients at risk of developing disseminated candidosis. [ABSTRACT FROM AUTHOR]

Study Objective. To evaluate the activity of cefepime, imipenem, tigecycline, and gentamicin, alone and in combination, against extended-spectrum β- lactamase (ESBL)-producing Klebsiella pneumoniae and Escherichia coli. Design. In vitro susceptibility and time-kill analysis. Setting. University-affiliated research laboratory. Isolates. Ten K. pneumoniae and 10 E. coli clinical strains known to produce ESBL. Measurements and Main Results. Minimum inhibitory concentration (MIC) testing was performed at 5.5 and 7.0 log10 colony-forming units (cfu)/ml. Time-kill studies were performed over 24 hours with a high inoculum of 7.0 log10 cfu/ml for cefepime, imipenem, tigecycline, and gentamicin at 1 times MIC. Combination studies were tested for cefepime plus tigecycline, cefepime plus imipenem, imipenem plus tigecycline, and for adjunctive gentamicin with cefepime, imipenem, or tigecycline. At the high inoculum, the MIC ranges for cefepime, imipenem, tigecycline, and gentamicin were 0.25-256 (MIC for 90% of tested strains [MIC90] = 32), 0.125-2 (MIC90 = 1), 0.25-16 (MIC90 = 4), and 0.25-4 mg/L (MIC90 = 1), respectively, for all isolates. At the higher inoculum, MICs shifted for cefepime, imipenem, and tigecycline. Change in logs10 cfu/ml from baseline to 24 hours for cefepime, imipenem, and tigecycline alone ranged from 4.85-0.71, 5-4.22, and 3.5-1.01, respectively, for all isolates. Bactericidal activity was observed for cefepime alone (10 [50%1 of 20 isolates), imipenem alone (20 [100%] of 20), and tigecycline alone (3 [15%] of 20). Combination studies with cefepime plus tigecycline resulted in synergy against 4 (20%) of 20' isolates. Combination studies with gentamicin resulted in synergy against 6 isolates (30%) with cefepime and 4 isolates (20%) with tigecycline. No synergy was observed with imipenem combinations. No antagonism was observed. With the exception of cefepime, correlations were observed between MIC and terminal densities for studied agents. Conclusions. Cefepime exhibited bactericidal activity but was unrelated to susceptibility. Tigecycline exhibited predictable bacteriostatic activity and synergy in combination against a subset of study isolates. Imipenem exhibited predictable bactericidal activity against all isolates. The utility of combination regimens with novel agents requires further exploration. [ABSTRACT FROM AUTHOR]

Background and objective: Multi-resistant coagulase-negative staphylococci (CNS) may cause systemic infections in patients undergoing bone marrow transplantation. Daptomycin, a new lipopeptide, and tigecycline, a new glycylcycline, have excellent activity against Gram-positive bacteria including methicillin-resistant staphylococci. This study presents the in vitro activity of daptomycin and tigecycline compared to vancomycin and fosfomycin against 105 CNS isolated from 76 bone marrow transplant patients with symptomatic bacteremia. Material and methods: Blood stream isolates of Staphylococcus epidermidis ( n = 102) and Staphylococcus haemolyticus ( n = 3) from bone marrow transplant patients were collected from 2000 to 2006. The susceptibility of all isolates was tested using methods of the Clinical Laboratory Standards Institute. Results: The minimal inhibitory concentrations MIC50 and MIC90 were 0.125 μg/mL and 0.25 μg/mL for daptomycin, 0.25 and 0.5 μg/mL for tigecycline, 1 μg/mL and 2 μg/mL for vancomycin, and 8 μg/mL and >256 μg/mL for fosfomycin, respectively. MIC values of tested agents were similar for both methicillin-sensitive and methicillin-resistant S. epidermidis strains. Conclusions: All CNS isolates were susceptible to the new antistaphylococcal agents daptomycin and tigecycline. Although vancomycin had been used over the past 30 yr at our bone marrow transplant unit all CNS were still susceptible to vancomycin. [ABSTRACT FROM AUTHOR]

A 53-year-old woman experienced a multidrug-resistant (MDR) Acinetobacter baumannii urinary tract infection 5 months after undergoing kidney and liver transplantation. The tigecycline minimum inhibitory concentration (MIC) for her A. baumannii isolate was 1.5 µg/ml; the patient received 2 weeks of therapy with intravenous tigecycline as a 100-mg loading dose followed by 50 mg every 12 hours, with no lapses in treatment and with resolution of the infection. Three weeks later, MDR A. baumannii was isolated from her sputum in the setting of clinical evidence of pneumonia, and tigecycline was restarted; the tigecycline MIC for the A. baumannii isolate was 2 µg/ml. At approximately the same time, the patient was found to have a paraspinal abscess and spinal osteomyelitis. Cultures of the abscess fluid grew A. baumannii with a tigecycline MIC of 24 µg/ml. A follow-up sputum culture again yielded A. baumannii, but with a tigecycline MIC of 24 µg/ml. Urine culture at that time also grew A. baumannii with a tigecycline MIC of 24 µg/ml. Clinicians should be aware that tigecycline MICs for A. baumannii isolates may increase during therapy with tigecycline after only brief exposure to the drug. Patients receiving tigecycline for Acinetobacter should be monitored for the development of clinical resistance, and isolates should be monitored for evidence of microbiologic resistance. [ABSTRACT FROM AUTHOR]

Strains of Klebsiella pneumoniae that produce one of three possible carbapenemases--KPC--have recently been identified with increasing frequency among isolates recovered from patients residing along the East Coast of the United States, particularly within the New York City metropolitan region. These strains have exhibited resistance to multiple antibiotic classes, including carbapenem agents. We report a case of nosocomial pneumonia and empyema caused by a KPC-producing isolate of K. pneumoniae at a large midwestern U.S. tertiary care facility in which the patient was treated with tigecycline. Although the pneumonia was treated successfully, the empyema recurred in association with a treatment-emergent tigecycline minimum inhibitory concentration (MIC) increase from 0.75 to 2 µg/ml. Clinicians should be aware of the potential occurrence of this treatment-emergent MIC increase, especially in the setting of sustained tigecycline therapy. In addition, the emergence of carbapenem-resistant Enterobacteriaceae reinforces the importance of antibiotic stewardship and strict infection control practices. [ABSTRACT FROM AUTHOR]

Study Objective. To evaluate early experience with tigecycline alone or in combination with other antimicrobials for treatment of ventilator-associated pneumonia (VAP) and/or bacteremia caused by multidrug-resistant Acinetobacter baumannii. Design. Retrospective case series. Setting. University-affiliated medical center. Patients. Twenty-five patients with multidrug-resistant A. baumannii who received tigecycline for VAP (19 patients), bacteremia (3), or VAP plus bacteremia (3) between September 1, 2005, and May 31, 2006. Five patients were treated with tigecycline alone. Measurements and Main Results. Primary outcomes were resolution of clinical signs and symptoms of the infection and documented microbial eradication of A. baumannii with tigecycline. Overall, 21 (84%) of the 25 patients had clinical resolution. Four had clinical failure: three with VAP and one with VAP plus bacteremia that developed resistance to tigecycline during therapy. Microbial eradication was demonstrated in 12 (80%) of 15 patients in whom repeat cultures were obtained. Three patients with VAP had a recurrence of infection: one patient had two recurrences, and two patients had one recurrence each. All four recurrent episodes led to clinical resolution and microbial eradication. No patients discontinued tigecycline because of adverse events. Conclusion. Tigecycline was effective in most of these 25 patients when used alone or in combination with other antimicrobials for VAP and/or bacteremia caused by multidrug-resistant A. baumannii. The emergence of a resistant strain while one patient was receiving therapy, however, is concerning. [ABSTRACT FROM AUTHOR]

Study Objective. To evaluate a potential interaction between tigecycline and digoxin using pharmacokinetic and pharmacodynamic assessments. Design. Open-label, three-period, one-sequence crossover study. Setting. Hospital-affiliated, inpatient clinical pharmacology unit. Subjects. Twenty healthy men. Intervention. Tigecycline 100 mg was administered intravenously as a single dose on day 1 (period 1). Digoxin was administered as a 0.5-mg oral loading dose on day 7, followed by 0.25 mg/day on days 8-14 (period 2). Digoxin 0.25 mg/day was continued on days 15-19; in addition, on day 15, a loading dose of tigecycline 100 mg was administered intravenously, followed by 50 mg every 12 hours starting on the evening of day 15 through the morning of day 19 (period 3). Measurements and Main Results. Pharmacokinetic assessments were performed on days 1 and 19 for tigecycline and on days 14 and 19 for digoxin. Electrocardiographic parameters were measured at baseline and on days 1, 14, and 19 to assess digoxin pharmacodynamics. Serum tigecycline concentrations were determined by liquid chromatography with tandem mass spectrometry detection, and plasma and urine digoxin concentrations were determined by radioimmunoassay. Tigecycline area under the concentration-time curve (AUC), AUC from 0-12 hours (AUC0-12), weight-normalized clearance, and mean resistance time were not affected by concomitant multiple-dose digoxin administration, but tigecycline half-life was decreased during period 1, apparently due to fewer detectable terminal concentrations in some subjects. Digoxin steady-state AUG0-24, weight-normalized oral dose clearance, cumulative amount of drug excreted in urine over 24 hours, renal clearance, and QTc (change from baseline) were not affected by multiple-dose tigecycline administration. Conclusion. No significant effects of tigecycline on digoxin pharmacokinetics and pharmacodynamics were noted, but a small effect of digoxin on tigecycline pharmacokinetics cannot be ruled out due to design issues with period 1 of the study. [ABSTRACT FROM AUTHOR]