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Background: Pathophysiological changes post‐liver transplantation impact the pharmacokinetics and pharmacodynamics of antibiotics. Piperacillin, often used in combination with tazobactam, is a key antibiotic after transplantation to its broad‐spectrum activity, but there is a lack of specific pharmacokinetic data in this population. This study aims to describe the pharmacokinetic parameters and target attainment of piperacillin in pediatric liver transplant recipients. Methods: Patients with preserved renal function (estimated glomerular filtration rate > 50 mL/min/1.73 m2) receiving intravenous piperacillin‐tazobactam at 112.5 mg/kg every 8 h (100 mg piperacillin/12.5 mg tazobactam), with a rapid infusion (0.5–1 h), were included. Two blood samples per child were collected during the same interval within 48 h of starting therapy. A Bayesian approach was applied to estimate individual pharmacokinetic parameters and perform dosing recommendations against Enterococcus spp., Enterobacterales and Pseudomonas aeruginosa. Results: Eight patients with median age of 8 months were included. Median piperacillin clearance and central volume of distribution for the cohort were 11.11 L/h/70 kg and 9.80 L/70 kg, respectively. Seven patients (87.5%) presented with concentrations below the target of 100% fT > MIC. Simulations suggested that these patients required more frequent dosing and extended duration of infusion to ensure target attainment. One patient (12.5%) had trough concentrations that exceed 16 mg/L and could receive a lower daily dose. Conclusions: This case series highlights the importance of personalized therapy in pediatric liver transplant recipients due to the unpredictable and highly variable piperacillin pharmacokinetics in this population. [ABSTRACT FROM AUTHOR]

Background: Novel β-lactam antibiotics as well as other kinds of antibiotics have been used to treat complicated urinary tract infections (cUTIs); however, their efficacy and safety remain controversial. Objective: We conducted a systematic review with meta-analysis to explore the efficacy and safety of novel β-lactam antibiotics versus other antibiotics against cUTIs. Methods: PubMed, Embase, and the Cochrane Central Register of Controlled Trials were searched systematically from inception through 15 March 2024 for clinical trials comparing novel β-lactam antibiotics with other antibiotics for treatment of cUTIs. Random-effects models were used to evaluate the impact of treatment on the risk ratio (RR) of clinical response, microbiologic response, adverse effects (AEs), serious adverse effects (SAEs). The quality of evidence was evaluated with the Cochrane Risk of Bias assessment tool. The review was registered in INPLASY (INPLASY202440054). Results: Ten randomized controlled trials involving 5, 925 patients met our inclusion criteria. Our meta-analysis revealed that there was no significant difference in overall clinical response (RR = 1.02), AEs (RR = 1.07), SAEs (RR = 1.20) between novel β-lactam antibiotics groups and other antibiotics groups. However, a significant difference was found in a subgroup of clinical cure rates at the end of treatment between novel β-lactam antibiotics groups and carbapenems groups, with low heterogeneity (RR = 1.02). A significant difference was observed in microbiologic response (RR = 1.11). Subgroup analysis revealed a significant difference in microbiologic response between novel BBL/BLS groups and carbapenems groups (RR = 1.13, I² = 21%, P = 0.005). Differences was observed between novel BBL/BLS groups and piperacillin/tazobactam sodium groups (RR = 1.21, I² = 70%, P = 0.02). Similar results were obtained from subgroup analysis of the difference in microbiologic response between novel β-lactam antibiotics groups and ertapenem groups (RR = 0.92, I² = 0, P = 0.01). Conclusion: Novel β-lactam antibiotics had similar overall clinical cure, AEs, SAE, to other antibiotics in the treatment of cUTIs. However, novel β-lactam antibiotics demonstrated superior clinical cure rates compared to carbapenems in a subgroup analysis, and exhibited better microbiologic response than other antibiotics. [ABSTRACT FROM AUTHOR]

Objective: Patients with peripheral artery occlusive disease (PAD) are at risk of developing foot ulcers, which can subsequently lead to foot infections and an increased risk of amputation. In cases of severe ischemic foot infections (IFIs), the empirical use of antibiotics can be limb-saving. However, there is currently no evidence-based guidance on the choice of empirical antibiotic therapy for IFI. Methods and Design: This retrospective single-center cohort study included 216 hospitalized patients with severe IFI undergoing endovascular revascularization. Weighted-Incidence Syndromic Combination Antibiograms (WISCAs) were calculated to guide empirical antibiotic choice. Results: The two most common causative pathogens for IFI were S. aureus and P. aeruginosa, with frequencies of 19.8% and 6.1%, respectively. The calculation of WISCAs revealed a low empirical coverage of amoxicillin (AMX) or clindamycin (CLN) with 21.6% and 27.7%, respectively. The empirical coverage of amoxicillin/clavulanic-acid (AMC), trimethoprim/sulfmethoxazole (SXT), and ciprofloxacin (CIP) was 50.6%, 53.1%, and 55.4%, respectively. Piperacillin/tazobactam (PT) exhibited the highest empirical coverage, with 82.5% as calculated by WISCAs. The calculated WISCAs did not significantly alter when stratified by the clinical characteristics of the patients. Conclusions: The empirical antibiotic coverage of CLN and AMX was low. SXT represents a promising empirical alternative in the case of IFI, irrespective of comorbidities and the WIfI score. WISCAs can assist in the decision-making process regarding empirical antibiotic therapy choices in cases of IFI. [ABSTRACT FROM AUTHOR]

Piperacillin is commonly used off‐label in neonates for the treatment of bacterial infections. This study aimed to assess a dried blood spots (DBS)‐based microsampling strategy for supporting population pharmacokinetics and treatment optimization of piperacillin in Chinese neonates. DBS samples from neonatal patients were collected at predefined intervals. Drug blood concentrations were quantified using a validated ultra‐high‐performance liquid chromatography‐tandem mass spectrometry method. A population pharmacokinetic model was developed using a nonlinear mixed‐effects modeling approach. The pharmacokinetic/pharmacodynamics (PK/PD) target was 75% of the time with the unbound drug plasma concentration above the minimum inhibitory concentration (fT>MIC), with a toxicity threshold of unbound drug plasma trough concentration above 64 mg/L. A total of 45 piperacillin samples from 24 neonates were collected. The pharmacokinetics of piperacillin was described using a one‐compartment model with postmenstrual age (PMA) as the most significant covariate on clearance. Simulations showed that dosing regimens achieving >90% PK/PD target attainment with <10% risk of possible toxicity were: PMA 33‐35 weeks (50 mg/kg q12h), 35‐37 weeks (50 mg/kg q8h), and 37‐41 weeks (50 mg/kg q6h). In conclusion, Using DBS sampling, we developed a population pharmacokinetic model of piperacillin in Chinese neonates, incorporating PMA to determine optimal dosing regimens. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance (AMR) poses a global health crisis demanding innovative solutions. Traditional antibiotics, though pivotal over the past century in combating bacterial infections, face diminished efficacy against evolving bacterial defense mechanisms, especially in Gram‐negative strains. This study explores self‐assembled ionizable lipid nanoparticles (LNPs) with the incorporation of two ionizable lipid components (one cationic, one anionic) in nanocarriers for advanced antimicrobial drug delivery of the broad‐spectrum antibiotic Piperacillin (Pip). Incorporating cationic ionizable lipid ALC‐0315, recognized as a functional lipid in the Pfizer‐BioNTech mRNA‐based SARS‐CoV‐2 vaccine, into LNPs allowed mesophase transition, pH responsiveness, and ionization behavior in acidic environments found in sites of bacterial infections, to be studied using synchrotron small angle X‐ray scattering, dynamic light scattering, and a 2‐(p‐toluidino)‐6‐naphthalene sulfonic acid assay. Incorporating another anionic ionizable lipid, oleic acid not only modulates the LNPs' physicochemical properties, such as size, internal phase nanostructure, and surface charge but also synergistically enhances the antimicrobial potency together with ALC‐0315 with a benefit enhancing permeability and fusion with bacterial membranes. This study introduces a strategy for tailoring ionizable lipid compositions in LNPs, providing a new approach to antimicrobial treatment contributing to the fight against AMR. [ABSTRACT FROM AUTHOR]

In this study, we evaluated the performance of the EUCAST RAST method on a collection of 154 clinical strains of P. aeruginosa, including strains resistant to ceftazidime and carbapenems. While the test is convenient for routine laboratories, we observed significant rates of VME (ranging from 0.0 to 15.0%) and ME (ranging from 1.3 to 16.3%) after 6 h, particularly for key antibiotics such as ceftazidime, piperacillin/tazobactam, and meropenem. Extending the incubation time to 8 h may improve results (CA ranging from 87.2 to 99%), but caution is required in interpretation due to persistence of VME (ranging from 0.0 to 15.6%) and ME (ranging from 0.0 to 11.7%). [ABSTRACT FROM AUTHOR]

This study aims to explore the in vitro antibacterial activity of 18 lichen species from Cangshan and the synergistic effect of their natural active products in combination with antibiotics against methicillin-resistant Staphylococcus aureus (MRSA). The in vitro antibacterial activity of 18 lichen species against 6 food-borne pathogens was determined using the agar well diffusion method, and the combined effect of active lichens and 7 common antibiotics was evaluated using the checkerboard method with MRSA as the tracer. Additionally, in vitro bactericidal curves, antimutagenic concentrations, and post-antibiotic effects were examined. The results demonstrated that 10 of the 18 lichen species exhibited in vitro anti-MRSA activity, with strongest antibacterial activity observed for Cetraria laevigata, showing extremely high sensitivity (the diameter of the inhibition zone was 22.0 mm). Furthermore, the combination of Lobaria kurokawae and Cladonia uncialis with piperacillin demonstrated a synergistic antibacterial effect, significantly reducing MRSA bacterial density (P<0.05), enhancing mutation prevention capability, and prolonging the post-antibiotic effect of piperacillin. These findings suggest that the extracts from various Cangshan lichen species exhibit promising antimicrobial activity against MRSA, and the combination of Lobaria kurokawae, Cladonia uncialis, and piperacillin shows a synergistic antibacterial effect, which have the potential for further development as antibiotics or antibiotic adjuvants. [ABSTRACT FROM AUTHOR]

Background: Open abdomen with vacuum-assisted wound closure therapy (OA/VAC) is frequently used in critically ill patients although the impact of OA/VAC on antibiotics pharmacokinetics (PK) remains unknown. We thus aimed to characterize the PK of piperacillin–tazobactam (PTZ) in critically ill patients with OA/VAC and assess the optimal dosing regimens based on pharmacodynamics (PD) target attainment. Methods: Over a 15-month study period, 45 patients with OA/VAC treated with PTZ administered continuously and adapted to 24 h creatinine clearance (CLCR) underwent measurements of free concentrations in their plasma, urine, VAC exudate, and peritoneal fluid. Population PK modeling was performed considering the effect of covariates, and Monte Carlo simulations were employed to determine the probability of target attainment (PTA) for the PK/PD targets (100% fT > 16 mg/L) in the plasma and at the peritoneal site at steady state. Results: Piperacillin concentrations were described using a two-compartment model, with age and total body weight as significant covariates for central volume of distribution (V1) and estimated renal function for clearance (CL). Tazobactam concentrations were described using a two-compartment model with estimated renal function as a significant covariate. The central volume of distributions V1 of piperacillin and tazobactam were 21.2 and 23.2 L, respectively. The VAC-induced peritoneal clearance was negligible compared to renal clearance. Most patients achieved the desirable PK/PD target when using a CLCR-pondered PTZ dosing regimen from 12 g/1.5 g/day to 20 g/2.5 g/day. Conclusions: Despite a wide inter-individual variability, the influence of OA/VAC on piperacillin and tazobactam PK parameters is not straightforward. The use of a CLCR-pondered PTZ dosing regimen from 12 g/1.5 g/day to 20 g/2.5 g/day is needed to reach a PTA > 85%. [ABSTRACT FROM AUTHOR]

The coronavirus disease of 2019 (COVID-19) emerged as a pandemic at the end of 2019. The clinical presentation of COVID-19 was comparable to bacterial infections, and due to the ambiguity of an effective treatment method, the healthcare professionals routinely used antibiotics to treat the patients. So, this study evaluated the antibiotic usage patterns at our hospitals among COVID-19 patients, considering the World Health Organization (WHO) AWaRe (Access, Watch, and Reserve) classification. The present study was a retrospective observational hospital record-based study on COVID-19 patients admitted from March-August 2020. A total of 256 COVID-19 patients were enrolled, considering inclusion and exclusion criteria. Data collection utilizing a standardized case record form to capture all information methodically based on age, sex, comorbidities, duration, and nature of the symptoms. Drug data, for example antibiotic usage patterns were collected with detailed prescription analysis, including route, dose, frequency and number of antibiotics used. A structured proforma was used to analyze data, and descriptive statistical analysis was performed and presented as Histograms. The WHO AWaRe antibiotic classification was used to determine the antibiotics' suitability for empirical therapy. The mean age of the participants was 40.00 ± 15.46 years with male predominance, 188 (73.43%) in number, compared to females, with 68 (26.56%). Almost all the current study participants received one or more antibiotics during their hospital stay, and a maximum of the patients 126 (49.22%) received 2 antibiotics during treatment, 78 (30.47%) subjects who were managed with 3 antibiotics, and the rest, 52 (20.31%) participants received only 1 antibiotic during their hospital stay. To treat moderate to severely ill patients, the most used antibiotic was doxycycline, followed by meropenem and piperacillin/tazobactam. The findings of this study will provide baseline data that will help to generate strategies to reduce antibiotic prescriptions for the formulation of better antibiotic stewardship programs (ASP) and institutional policies to fight against any infection in a better way in the near future. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to evaluate antibiotic susceptibility and antimicrobial resistance trends among clinically significant anaerobes in Kuwait hospitals from 2013 to 2022, comparing these findings with data from 2002 to 2012. Methods: The study prospectively collected 2,317 anaerobic isolates from various body sites across four Kuwaiti hospitals between January 2013 and December 2022. The minimum inhibitory concentrations for 11 antianaerobic antibiotics were determined using E-test methodology. The study analyzed trends and resistance rates across two periods: 2013–2017 and 2018–2022, using statistical analysis for resistance comparison. Results: Of the 2,317 isolates, most were from wounds (42.2%), fluids (28.0%), and tissues (20.5%). Bacteroides fragilis was the most common pathogen (34.0%), followed by Prevotella bivia (13.4%). Over 90% of isolates were susceptible to imipenem, meropenem, tigecycline, and metronidazole, whereas lower susceptibility was observed for penicillin, amoxicillin–clavulanic acid, and clindamycin. Notable differences in resistance profiles since 2002 were observed, especially in amoxicillin–clavulanic acid, piperacillin, piperacillin–tazobactam, and clindamycin. Conclusion: Owing to detected resistance to all antibiotics, susceptibility testing for anaerobic isolates is recommended in severe infections to ensure effective antimicrobial therapy. Continuous surveillance is crucial for developing antibiotic policies to manage invasive anaerobic infections. [ABSTRACT FROM AUTHOR]

Background β-lactam antibiotics, which inhibit penicillin-binding protein 3 (PBP3) that is required for cell division, play a key role in treating P. aeruginosa infections. Some sequence variations in PBP3 have been associated with β-lactam resistance but the effects of variations on antibiotic susceptibility and on cell division have not been quantified. Antibiotic efflux can also reduce susceptibility. Objectives To quantify the effects of PBP3 variations on β-lactam susceptibility and cell morphology in P. aeruginosa. Methods Nineteen PBP3 variants were expressed from a plasmid in the reference strain P. aeruginosa PAO1 and genome engineering was used to construct five mutants expressing PBP3 variants from the chromosome. The effects of the variations on β-lactam minimum inhibitory concentration (MIC) and cell morphology were measured. Results Some PBP3 variations reduced susceptibility to a variety of β-lactam antibiotics including meropenem, ceftazidime, cefepime and ticarcillin with different variations affecting different antibiotics. None of the tested variations reduced susceptibility to imipenem or piperacillin. Antibiotic susceptibility was further reduced when PBP3 variants were expressed in mutant bacteria overexpressing the MexAB-OprM efflux pump, with some variations conferring clinical levels of resistance. Some PBP3 variations, and sub-MIC levels of β-lactams, reduced bacterial growth rates and inhibited cell division, causing elongated cells. Conclusions PBP3 variations in P. aeruginosa can increase the MIC of multiple β-lactam antibiotics, although not imipenem or piperacillin. PBP3 variations, or the presence of sub-lethal levels of β-lactams, result in elongated cells indicating that variations reduce the activity of PBP3 and may reduce bacterial fitness. [ABSTRACT FROM AUTHOR]

Background: The combination of vancomycin and piperacillin-tazobactam (VPT) has been associated with acute kidney injury (AKI) in hospitalized patients when compared to similar combinations. Additional studies examining this nephrotoxic risk in critically ill patients have not consistently demonstrated the aforementioned association. Furthermore, patients with baseline renal dysfunction have been excluded from almost all of these studies, creating a need to examine the risk in this patient population. Methods: This was a retrospective cohort analysis of critically ill adults with baseline chronic kidney disease (CKD) who received vancomycin plus an anti-pseudomonal beta-lactam at Emory University Hospital. The primary outcome was incidence of AKI. Secondary outcomes included stage of AKI, time to development of AKI, time to return to baseline renal function, new requirement for renal replacement therapy, intensive care unit and hospital length of stay, and in-hospital mortality. Results: A total of 109 patients were included. There was no difference observed in the primary outcome between the VPT (50%) and comparator (58%) group (P =.4), stage 2 or 3 AKI (15.9% vs 6%; P =.98), time to AKI development (1.7 vs 2 days; P =.5), time to return to baseline renal function (4 vs 3 days; P =.2), new requirement for RRT (4.5% vs 1.5%; P =.3), ICU length of stay (7.3 vs 7.4 days; P =.9), hospital length of stay (19.3 vs 20.1 days; P =.87), or in-hospital mortality (15.9% vs 10.8%; P =.4). A significant difference was observed in the duration of antibiotic exposure (3.32 vs 2.62 days; P =.045 days). Conclusion: VPT was not associated with an increased risk of AKI or adverse renal outcomes. Our findings suggest that the use of this antibiotic combination should not be avoided in this patient population. More robust prospective studies are warranted to confirm these findings. [ABSTRACT FROM AUTHOR]

We evaluated the activity of piperacillin in relation to increasing tazobactam concentration against ESBL-producing Enterobacterales collected from patients with bacteraemia. Increasing tazobactam concentration (4, 12 or 24 mg/L) exerted a reduction of piperacillin MICs under the clinical breakpoint in a concentration-dependent manner (0%, 60% and 90% of clinical isolates). Also, activity of piperacillin/tazobactam based at higher achievable serum concentrations (123/14 mg/L) is needed to reduce the bacterial growth in 92% of ESBL-producers. Changes in the piperacillin MIC in relation to increasing tazobactam suggest that realtime TDM could be used for driven antimicrobial therapy with piperacillin/tazobactam in BSI due to ESBL strains. [ABSTRACT FROM AUTHOR]

Background: Piperacillin/tazobactam may be associated with less favourable outcomes than carbapenems in patients with severe bacterial infections, but the certainty of evidence is low. Methods: The Empirical Meropenem versus Piperacillin/Tazobactam for Adult Patients with Sepsis (EMPRESS) trial is an investigator‐initiated, international, parallel‐group, randomised, open‐label, adaptive clinical trial with an integrated feasibility phase. We will randomise adult, critically ill patients with sepsis to empirical treatment with meropenem or piperacillin/tazobactam for up to 30 days. The primary outcome is 30‐day all‐cause mortality. The secondary outcomes are serious adverse reactions within 30 days; isolation precautions due to resistant bacteria within 30 days; days alive without life support and days alive and out of hospital within 30 and 90 days; 90‐ and 180‐day all‐cause mortality and 180‐day health‐related quality of life. EMPRESS will use Bayesian statistical models with weak to somewhat sceptical neutral priors. Adaptive analyses will be conducted after follow‐up of the primary outcome for the first 400 participants concludes and after every 300 subsequent participants, with adaptive stopping for superiority/inferiority and practical equivalence (absolute risk difference <2.5%‐points) and response‐adaptive randomisation. The expected sample sizes in scenarios with no, small or large differences are 5189, 5859 and 2570 participants, with maximum 14,000 participants and ≥99% probability of conclusiveness across all scenarios. Conclusions: EMPRESS will compare the effects of empirical meropenem against piperacillin/tazobactam in adult, critically ill patients with sepsis. Due to the pragmatic, adaptive design with high probability of conclusiveness, the trial results are expected to directly inform clinical practice. [ABSTRACT FROM AUTHOR]

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Background: Carbapenem resistance in Pseudomonas aeruginosa is a serious global health problem. We investigated the clonal distribution and its association with the carbapenem resistance mechanisms of carbapenem-non-susceptible P. aeruginosa isolates from three Korean hospitals. Methods: A total of 155 carbapenem-non-susceptible P. aeruginosa isolates collected between 2011 and 2019 were analyzed for sequence types (STs), antimicrobial susceptibility, and carbapenem resistance mechanisms, including carbapenemase production, the presence of resistance genes, OprD mutations, and the hyperproduction of AmpC ß-lactamase. Results: Sixty STs were identified in carbapenem-non-susceptible P. aeruginosa isolates. Two high-risk clones, ST235 (N=41) and ST111 (N=20), were predominant; however, sporadic STs were more prevalent than high-risk clones. The resistance rate to amikacin was the lowest (49.7%), whereas that to piperacillin was the highest (92.3%). Of the 155 carbapenem-non-susceptible isolates, 43 (27.7%) produced carbapenemases. Three metallo-β-lactamase (MBL) genes, blaIMP-6 (N=38), blaVIM-2(N=3), and blaNDM-1(N=2), were detected. blaIMP-6 was detected in clonal complex 235 isolates. Two ST773 isolates carried blaNDM-1 and rmtB. Frameshift mutations in oprD were identified in all isolates tested, regardless of the presence of MBL genes. Hyperproduction of AmpC was detected in MBL gene-negative isolates. Conclusions: Frameshift mutations in oprD combined with MBL production or hyperproduction of AmpC are responsible for carbapenem resistance in P. aeruginosa. Further attention is required to curb the emergence and spread of new carbapenem-resistant P. aeruginosa clones. [ABSTRACT FROM AUTHOR]

Efflux-mediated β-lactam resistance is a major public health concern, reducing the effectiveness of β-lactam antibiotics against many bacteria. Structural analyses show the efflux protein TolC in Gram-negative bacteria acts as a channel for antibiotics, impacting bacterial susceptibility and virulence. This study examines β-lactam drug efflux mediated by TolC using experimental and computational methods. Molecular dynamics simulations of drug-free TolC reveal essential movements and key residues involved in TolC opening. A whole-gene-saturation mutagenesis assay, mutating each TolC residue and measuring fitness effects under β-lactam selection, is performed. Here we show the TolC-mediated efflux of three antibiotics: oxacillin, piperacillin, and carbenicillin. Steered molecular dynamics simulations identify general and drug-specific efflux mechanisms, revealing key positions at TolC's periplasmic entry affecting efflux motions. Our findings provide insights into TolC's structural dynamics, aiding the design of new antibiotics to overcome bacterial efflux mechanisms. Modelling and deep mutational scanning of TolC provide insights for designing β-lactams to evade resistance, by outlining how efflux is fine-tuned for efficiency via transient hydrogen bonds with antibiotics and how allostery impacts exit site motions. [ABSTRACT FROM AUTHOR]

Organosulfur compounds derived from plants of the Allium genus, such as propyl‐propane‐thiosulfinate (PTS) and propyl‐propane‐thiosulfonate (PTSO), have been proposed as an alternative in antibiotic resistance. The aim of this study was to compare the activity of these substances with other antibiotics against clinical isolates of carbapenem‐resistant (CAR‐R) and carbapenem‐susceptible (CAR‐S) Gram‐negative bacteria. A total of 126 clinical isolates of CAR‐R and 155 CAR‐S bacteria were selected, including Enterobacterales, A. baumannii and P. aeruginosa. The antibiotic susceptibility of all isolates was assessed using the microdilution and Kirby–Bauer methods for PTS, PTSO, amoxicillin/clavulanate, piperacillin/tazobactam, cefotaxime, ceftazidime, cefepime, imipenem, ciprofloxacin, and amikacin. Both PTS and PTSO demonstrated in vitro bactericidal activity against CAR‐R Enterobacteriaceae and A. baumannii, with no significant difference in activity compared to their response against CAR‐S isolates. However, both compounds were less active against P. aeruginosa than against any of the other bacteria, regardless of their resistance to carbapenems. In all cases, the minimum inhibitory concentration values of PTSO were significantly lower than those of PTS. These findings offer valuable information about the potential antibacterial use of these substances, particularly against infections that currently have limited therapeutic options. [ABSTRACT FROM AUTHOR]

Objectives To investigate clinical outcomes of patients with Pseudomonas endocarditis and identify factors associated with treatment failure. Methods Adult patients meeting definitive Duke's criteria for Pseudomonas endocarditis at 11 hospitals were identified between May 2000 and February 2024. Failure was defined as death or microbiological failure by day 42. First-line therapy consisted of cefepime, piperacillin/tazobactam, ceftazidime or ceftolozane/tazobactam alone or in combination. Results Forty-eight patients met inclusion criteria; 29% were persons who inject drugs and 13% were organ transplant recipients. Pseudomonas aeruginosa was the causative species in 98% of cases. Patients who experienced 42 day cure were more likely to be initially managed with first-line β-lactam agents compared with those who experienced clinical failure (97% versus 62%, P  = 0.004). Treatment with first-line β-lactams was associated with shorter time to treatment initiation and a lower likelihood of infection due to MDR Pseudomonas spp. In the univariate model, patients who experienced 90 day mortality were more likely to have prosthetic valve endocarditis (57% versus 24%, P  = 0.02), an intracardiac complication (36% versus 9%, P  = 0.04) and a higher median (IQR) Pitt bacteraemia score [2.5 (2–3.8) versus 1 (0–2), P  = 0.048]. Combination therapy did not improve clinical outcomes but did increase the rate of adverse effects resulting in drug discontinuation compared with monotherapy, (21% versus 0%, P  = 0.08). Conclusions This is the largest study of Pseudomona s endocarditis to date. We identified improved clinical outcomes when cefepime, piperacillin/tazobactam, ceftazidime or ceftolozane/tazobactam were used for initial treatment. We did not identify a clinical benefit for combination treatment. [ABSTRACT FROM AUTHOR]

Background: Surgical site infection (SSI) after liver transplant (LT) is common, but no studies have been conducted in Australia. The purpose of this study was to determine the proportion of patients who developed an SSI post‐LT in Australia's largest LT unit. Methods: This was a single‐center retrospective cohort study. We included all LT recipients who were aged 18 years or more and received their transplant between March 1, 2018 and April 1, 2023. The primary outcome was to determine the proportion of LT recipients who developed an SSI within 30 days of transplantation. Results: There were 404 LTs performed during the study period, and 375 met inclusion criteria. Of these, 8% (n = 31/375) developed an SSI and were classified as superficial (3%, n = 12/375) or deep/organ space (5%, n = 19/375). The most common antibiotics used for prophylaxis were amoxicillin/clavulanate (75%, n = 281/375), followed by piperacillin/tazobactam (17%, n = 62/375). Independent risk factors associated with the development of SSI were Roux‐en‐Y hepaticojejunostomy (aOR 3.16, 95% CI 1.17–8.28, p =.02), operative time (per 60‐min increment) (aOR 1.23, 95% CI 1.02–1.48), and re‐operation (aOR 4.16, 95% CI 1.81–9.58, p <.01). Type of antibiotic received perioperatively was not significantly associated with SSI. Conclusion: SSI occurred in 8% of LT recipients and was predominantly related to operation‐related factors rather than patient‐ or antibiotic‐related factors. [ABSTRACT FROM AUTHOR]

Background and Objective: Renal replacement therapy (RRT) plays a critical role in antimicrobial removal, particularly for low-molecular-weight drugs with low plasma protein binding, low distribution volume and hydrophilicity. Medium cut-off (MCO) membranes represent a new generation in dialysis technology, enhancing diffusive modality efficacy and increasing the cut-off from 30 to 45 kDa, crucial for middle molecule removal. This monocentric randomized crossover pilot study aimed to evaluate the impact of continuous haemodialysis with MCO membrane (MCO-CVVHD) on the removal of piperacillin, tazobactam and meropenem compared with continuous veno-venous hemodiafiltration with standard high-flux membrane (HFM-CVVHDF). Methods: Twenty patients were randomized to undergo MCO-CVVHD followed by HFM-CVVHDF or vice versa. Extraction ratio (ER), effluent clearance (Cleff) and treatment efficiency were assessed at various intervals. Antibiotic nadir plasma levels were measured for both treatment days. Results: HFM-CVVHDF showed greater ER compared with MCO-CVVHD for meropenem (β = − 8.90 (95% CI − 12.9 to − 4.87), p < 0.001) and tazobactam (β = − 8.29 (95% CI − 13.5 to − 3.08), p = 0.002) and Cleff for each antibiotic (meropenem β = − 10,206 (95% CI − 14,787 to − 5787), p = 0.001); tazobactam (β = − 4551 (95% CI − 7781 to − 1322), p = 0.012); piperacillin (β = − 3913 (95% CI − 6388 to − 1437), p = 0.002), even if the carryover effect influenced the Cleff for meropenem and tazobactam. No difference was observed in nadir plasma concentrations or efficiency for any antibiotic. Piperacillin (β = − 38.1 (95% CI − 47.9 to − 28.3), p < 0.001) and tazobactam (β = − 4.45 (95% CI − 6.17 to − 2.72), p < 0.001) showed lower nadir plasma concentrations the second day compared with the first day, regardless the filter type. Conclusion: MCO demonstrated comparable in vivo removal of piperacillin, tazobactam and meropenem to HFM. [ABSTRACT FROM AUTHOR]

This is the first case report of decubitus infection and bacteremia due to Veillonella parvula (V. parvula). A patient in his 70s with pre-existing diabetes mellitus was admitted with decubitus infection, and tazobactam/piperacillin treatment was initiated. Tazobactam/piperacillin-resistant V. parvula was detected in the blood and decubitus site cultures. The antimicrobial treatment was changed to clindamycin and cefmetazole. Antimicrobial therapy was administered for 28 days. The patient was transferred to a convalescent hospital. V. parvula occasionally causes infection in immunocompromised patients with underlying diseases, such as diabetes. An appropriate evaluation by culture test is important for diagnosis, treatment, and recurrence prevention. Tazobactam/piperacillin is often used in the treatment of multi-bacterial infections such as decubitus infections. V. parvula may be resistant to tazobactam/piperacillin, and this possibility should be taken into account when administering treatment. [ABSTRACT FROM AUTHOR]

Pulmonary infections complicate chronic lung diseases requiring attention to both the pathophysiology and complexity associated with infection management. Patients with cystic fibrosis (CF) struggle with continuous bouts of pulmonary infections, contributing to lung destruction and eventual mortality. Additionally, CF patients struggle with airways that are highly viscous, with accumulated mucus creating optimal environments for bacteria colonization. The unique physiology and altered airway environment provide an ideal niche for bacteria to change their phenotype often becoming resistant to current treatments. Colonization with multiple pathogens at the same time further complicate treatment algorithms, requiring drug combinations that can challenge CF patient tolerance to treatment. The goal of this research initiative was to explore the utilization of a microparticle antibiotic delivery system, which could provide localized and sustained antibiotic dosing. The outcome of this work demonstrates the feasibility of providing efficient localized delivery of antibiotics to manage infection using both preclinical in vitro and in vivo CF infection models. The studies outlined in this manuscript demonstrate the proof-of-concept and unique capacity of polymerized cyclodextrin microparticles to provide site-directed management of pulmonary infections. [ABSTRACT FROM AUTHOR]

Objective: Piperacillin/tazobactam (PIP/TAZ) is used for the treatment of lower respiratory tract bacterial infections in children. This study was performed to evaluate if the current dosing regimen results in therapeutic drug concentrations. Patients and methods: Patients suspected or proven to have lower respiratory tract bacterial infection and administrated PIP/TAZ intravenously for a duration of no less than 0.5 h, q6h-q12h daily, were enrolled. Blood samples were collected, and PIP concentrations were determined by high-performance liquid chromatography. The individual predicted concentration of PIP was evaluated using the individual empirical Bayesian estimate method. The evaluated PK/PD targets included (1) 70% time when the predicted free drug concentration exceeds the minimum inhibitory concentration (fT > MIC) and (2) 50% fT > 4× MIC. Probability of target attainment (PTA) was assessed by the proportion of patients who reached the PK/PD targets. The PIP concentrations between different groups of patients were compared. Results: A total of 57 samples were collected from 57 patients with a median age of 2.26 years (0.17-12.58). For the PK/PD targets of 70% fT > MIC and 50% fT > 4× MIC for Pseudomonas aeruginosa and Klebsiella pneumoniae, the PTA was all 0. The median Cmin of PIP was significantly higher in infants than in children, and the median Cmin after administration in q8h was significantly higher than that after administration in q12h. Conclusion: The current dose regimen of PIP/TAZ leads to extremely low plasma concentrations in most children with lower respiratory tract bacterial infections. More optimized dosing regimens or better alternative therapies need to be further explored. [ABSTRACT FROM AUTHOR]

Introduction: Acinetobacter baumannii is a multidrug-resistant bacterium commonly associated with hospital-acquired infections. The rapid spread of A. baumannii has raised concerns, as it has been linked to the emergence of clones in healthcare facilities worldwide. The challenges of treating and controlling infections caused by this bacterium in hospital settings are exacerbated by its resistance profile. The proliferation of clones worldwide highlights the need for careful infection control procedures and new tactics to fight illnesses caused by drug-resistant A. baumannii strains. Materials and Methods: Between January 2019 and December 2020, a total of 26,250 specimens were collected by personnel from the Department of Microbiology at King Fahad Specialist Hospital. Results: Our study highlights a significant surge in antimicrobial resistance, indicating a relative increase in multidrug-resistant A. baumannii isolates. Despite extensive resistance, azithromycin, cefoxitin, norfloxacin, penicillin, piperacillin, tetracycline, ceftriaxone, nitrofurantoin and aztreonam showed 91.2%-100% efficacy against these strains. Conclusions: This study emphasises the critical need for stringent infection control measures and judicious antibiotic strategies to curb multidrug-resistant A. baumannii outbreaks in healthcare settings. The identification of alternative therapies is imperative for improved management of infections caused by multidrug-resistant A. baumannii. [ABSTRACT FROM AUTHOR]

Background The bla B, bla GOB and bla CME genes are thought to confer β-lactam resistance to Elizabethkingia anophelis , based on experiments conducted primarily on Escherichia coli. Objectives To determine the individual contributions of β-lactamase genes to increased MICs in E. anophelis and to assess their impact on the in vivo efficacy of carbapenem therapy. Methods Scarless gene deletion of one or more β-lactamase gene(s) was performed in three clinical E. anophelis isolates. MICs were determined by broth microdilution. Hydrolytic activity and expressions of β-lactamase genes were measured by an enzymatic assay and quantitative RT–PCR, respectively. In vivo efficacy was determined using Galleria mellonella and murine thigh infection models. Results The presence of bla B resulted in >16-fold increases, while bla GOB caused 4–16-fold increases of carbapenem MICs. Hydrolysis of carbapenems was highest in lysates of bla B-positive strains, possibly due to the constitutionally higher expression of bla B. Imipenem was ineffective against bla B-positive isolates in vivo in terms of improvement of the survival of wax moth larvae and reduction of murine bacterial load. The deletion of bla B restored the efficacy of imipenem. The bla B gene was also responsible for a >4-fold increase of ampicillin/sulbactam and piperacillin/tazobactam MICs. The presence of bla CME, but not bla B or bla GOB, increased the MICs of ceftazidime and cefepime by 8–16- and 4–8-fold, respectively. Conclusions The constitutionally and highly expressed bla B gene in E. anophelis was responsible for increased MICs of carbapenems and led to their poor in vivo efficacy. bla CME increased the MICs of ceftazidime and cefepime. [ABSTRACT FROM AUTHOR]

Background: Critically ill patients in intensive care units (ICU) are frequently administered broad‐spectrum antibiotics (e.g., carbapenems or piperacillin/tazobactam) for suspected or confirmed infections. This retrospective cohort study aimed to describe the use of carbapenems and piperacillin/tazobactam in two international, prospectively collected datasets. Methods: We conducted a post hoc analysis of data from the "Adjunctive Glucocorticoid Therapy in Patients with Septic Shock" (ADRENAL) trial (n = 3713) and the "Antimicrobial de‐escalation in the critically ill patient and assessment of clinical cure" (DIANA) study (n = 1488). The primary outcome was the proportion of patients receiving initial antibiotic treatment with carbapenems and piperacillin/tazobactam. Secondary outcomes included mortality, days alive and out of ICU and ICU length of stay at 28 days. Results: In the ADRENAL trial, carbapenems were used in 648 out of 3713 (17%), whereas piperacillin/tazobactam was used in 1804 out of 3713 (49%) participants. In the DIANA study, carbapenems were used in 380 out of 1480 (26%), while piperacillin/tazobactam was used in 433 out of 1488 (29%) participants. Mortality at 28 days was 23% for patients receiving carbapenems and 24% for those receiving piperacillin/tazobactam in ADRENAL and 23% and 19%, respectively, in DIANA. We noted variations in secondary outcomes; in DIANA, patients receiving carbapenems had a median of 13 days alive and out of ICU compared with 18 days among those receiving piperacillin/tazobactam. In ADRENAL, the median hospital length of stay was 27 days for patients receiving carbapenems and 21 days for those receiving piperacillin/tazobactam. Conclusions: In this post hoc analysis of ICU patients with infections, we found widespread initial use of carbapenems and piperacillin/tazobactam in international ICUs, with the latter being more frequently used. Randomized clinical trials are needed to assess if the observed variations in outcomes may be drug‐related effects or due to confounders. [ABSTRACT FROM AUTHOR]

Background/Aim: We evaluated the usefulness of prophylactic mini-tracheostomy (PMT) and perioperative administration of tazobactam/piperacillin (TAZ/PIPC) in high-risk patients after esophagectomy. Patients and Methods: We retrospectively studied 89 consecutive high-risk patients who underwent esophagectomy for esophageal cancer between January 2013 and December 2021. We defined patients with two or more of the following factors as high risk: age ≥70 years, performance status ≥1, respiratory dysfunction, liver dysfunction, cardiac dysfunction, renal dysfunction, diabetes mellitus, albumin <3.5 g/dl, and Brinkman index >600. Standard management was administered to the first 50 patients (standard group). PMT and TAZ/PIPC were administered to the next 39 patients (combination group). Patient characteristics and short-term outcomes were compared before and after propensity-score matching. Results: Before propensity-score matching, 24-hour urine creatinine clearance, retrosternal route, 3-field lymph node dissection, and open abdominal approach were more common, postoperative pneumonia (13% vs. 36%, p=0.045) and complications of grade ≥3b (2.6% vs. 22%, p=0.01) were less frequent, and the postoperative hospital stay was shorter (median: 23 vs. 28 days, p=0.022) in the combination group than in the standard group. In propensity-score matching, patient characteristics, except for 24-h creatinine clearance and reconstructive route, were matched for 23 paired patients. Postoperative pneumonia (8.7% vs. 39%, p=0.035) and complications of grade ≥3b (0% vs. 26%, p=0.022) were less frequent and postoperative hospital stay was shorter (median: 22 vs. 25 days, p=0.021) in the combination group than in the standard group. Conclusion: PMT with TAZ/PIPC can potentially prevent postoperative pneumonia in high-risk patients after esophagectomy. [ABSTRACT FROM AUTHOR]

The stability of antibiotic preanalytical samples is a critical factor in therapeutic drug monitoring (TDM), a practice of undoubted importance for the proper therapeutic use of antibiotics, especially in complex management patients, such as pediatrics. This review aims to analyze the data in the literature regarding the preanalytical stability of some of the antibiotics for which TDM is most frequently requested. The literature regarding the preanalytical stability of amikacin, ampicillin, cefepime, ceftazidime, ciprofloxacin, daptomycin, gentamicin, levofloxacin, linezolid, meropenem, piperacillin, teicoplanin, and vancomycin in plasma, serum, whole blood, and dried blood/plasma spot samples was analyzed. Various storage temperatures (room temperature, 4 °C, −20 °C, and −80 °C) and various storage times (from 1 h up to 12 months) as well as subjecting to multiple freeze–thaw cycles were considered. The collected data showed that the non-beta-lactam antibiotics analyzed were generally stable under the normal storage conditions used in analytical laboratories. Beta-lactam antibiotics have more pronounced instability, particularly meropenem, piperacillin, cefepime, and ceftazidime. For this class of antibiotics, we suggest that storage at room temperature should be limited to a maximum of 4 h, storage at 2–8 °C should be limited to a maximum of 24 h, and storage at −20 °C should be limited to a maximum of 7 days; while, for longer storage, freezing at −80 °C is suggested. [ABSTRACT FROM AUTHOR]

Background: The COVID-19 pandemic posed numerous challenges to public health systems, particularly in antimicrobial stewardship. This study aimed to assess antibiotic consumption before and during the COVID-19 pandemic to evaluate the effectiveness of the implemented antimicrobial stewardship program. Methods: This retrospective study was carried out at the University Hospital in Krakow, Poland, between 1 January 2019 and 31 December 2020. A total of 80,639 patients were enrolled. Antibiotic usage was measured as the percentage of patients receiving antibiotics and the number of days of therapy (DOTs). The World Health Organization (WHO) methodology and Anatomical Therapeutic Chemical (ATC) codes and AWaRe classification were utilized. The analyzed ATC antibiotic groups included penicillins (J01CA, J01CE, J01CF, J01CR, excluding piperacillin/tazobactam), piperacillin with tazobactam-beta-lactamase inhibitor (J01CR05), third- and fourth-generation cephalosporins (J01DD, J01DE), carbapenems (J01DH), macrolides (J01FA), fluoroquinolones (J01M), colistin (J01XB01), metronidazole (J01XD01) and others (J01DF, J01DI, J01E, J01G, J01XA, J01A). In the AWaRe classification, Access, Watch and Reserve groups of antibiotics were included. Results: In 2020, 79.2% of COVID-19 patients and 40.1% of non-COVID-19 patients were treated with antibiotics, compared to 28.8% in 2019. Also, in 2020, the antibiotic consumption in non-ICU COVID-19 patients was twice as high as in non-COVID-19 patients: 50.9 vs. 38.5 DOTs/100 patient days (pds). Conversely, in the ICU, antibiotic consumption in COVID-19 patients was 112.1 DOTs/100 pds compared to 248.9 DOTs/100 pds in non-COVID-19 patients. Significant increases were observed in the usage of third- and fourth-generation cephalosporins in 2020. The analysis according to the AWaRe system revealed the highest usage of the Watch group—ranging from 61.9% to 78.7%—and very high usage of the Reserve group—from 5.8% to 11.1%—in non COVID-19 and COVID-19 patients, respectively. Conclusions: Our findings highlight substantial issues with antibiotic use both before and during the COVID-19 pandemic. The results underscore the urgent need for improved antimicrobial stewardship policy implementation. [ABSTRACT FROM AUTHOR]

Cefepime and piperacillin/tazobactam are antimicrobials recommended by IDSA/ATS guidelines for the empirical management of patients admitted to the intensive care unit (ICU) with community-acquired pneumonia (CAP). Concerns have been raised about which should be used in clinical practice. This study aims to compare the effect of cefepime and piperacillin/tazobactam in critically ill CAP patients through a targeted maximum likelihood estimation (TMLE). A total of 2026 ICU-admitted patients with CAP were included. Among them, (47%) presented respiratory failure, and (27%) developed septic shock. A total of (68%) received cefepime and (32%) piperacillin/tazobactam-based treatment. After running the TMLE, we found that cefepime and piperacillin/tazobactam-based treatments have comparable 28-day, hospital, and ICU mortality. Additionally, age, PTT, serum potassium and temperature were associated with preferring cefepime over piperacillin/tazobactam (OR 1.14 95% CI [1.01–1.27], p = 0.03), (OR 1.14 95% CI [1.03–1.26], p = 0.009), (OR 1.1 95% CI [1.01–1.22], p = 0.039) and (OR 1.13 95% CI [1.03–1.24], p = 0.014)]. Our study found a similar mortality rate among ICU-admitted CAP patients treated with cefepime and piperacillin/tazobactam. Clinicians may consider factors such as availability and safety profiles when making treatment decisions. [ABSTRACT FROM AUTHOR]

Amikacin and piperacillin/tazobactam are frequent antibiotic choices to treat bloodstream infection, which is commonly fatal and most often caused by bacteria from the family Enterobacterales. Here we show that two gene cassettes located side-by-side in and ancestral integron similar to In37 have been "harvested" by insertion sequence IS26 as a transposon that is widely disseminated among the Enterobacterales. This transposon encodes the enzymes AAC(6')-Ib-cr and OXA-1, reported, respectively, as amikacin and piperacillin/tazobactam resistance mechanisms. However, by studying bloodstream infection isolates from 769 patients from three hospitals serving a population of 1.2 million people in South West England, we show that increased enzyme production due to mutation in an IS26/In37-derived hybrid promoter or, more commonly, increased transposon copy number is required to simultaneously remove these two key therapeutic options; in many cases leaving only the last-resort antibiotic, meropenem. These findings may help improve the accuracy of predicting piperacillin/tazobactam treatment failure, allowing stratification of patients to receive meropenem or piperacillin/tazobactam, which may improve outcome and slow the emergence of meropenem resistance. Author summary: Piperacillin/tazobactam and amikacin are common antibiotic choices for treating bloodstream infections, which are potentially lethal and predominantly caused by the bacterium Escherichia coli. By studying a large collection of bloodstream E. coli we show that dual resistance to piperacillin/tazobactam and amikacin is unexpectedly common. We explain this by showing that two resistance genes are circulating widely as part of a transposon. We show that genetic changes in the transposon, most commonly an increase in the number of copies of the transposon in the genome, are required to confer co-resistance to both antibiotics. Hence we have identified an important, emerging, mobile genetic element with the potential to compromise therapy by two commonly used antibiotics for bloodstream infection. We also show how this knowledge might be used to improve the sensitivity of tests for piperacillin/tazobactam resistance by integrating the results of amikacin resistance testing, reducing treatment failure and sparing last resort antibiotics. [ABSTRACT FROM AUTHOR]