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Background: Staphylococcus aureus has a great ability to form biofilms on implant-related biomaterials. This study aimed to investigate the resistance, biofilm and molecular characteristics of S. aureus strains isolated from patients with postoperative infections after arthroplasty in two Chinese tertiary care hospitals during 2017 to 2018., Methods: Antimicrobial susceptibility was determined by the agar dilution method. Bacterial biofilm formation was determined by crystal violet staining. The genes related to biofilm formation and molecular typing were analyzed by PCR amplification., Results: A total of 33 isolates were collected, 21 of which were from Henan. The strains were completely sensitive to vancomycin, linezolid, and nitrofurantoin. All the isolates had adhesion ability and could produce biofilms. Of the isolates, 75.0% from Chongqing and 85.7% from Henan had stronger biofilm formation abilities. The strains from Henan had slightly higher resistance, adhesion and biofilm-forming abilities than those from Chongqing. The strains in both hospitals carried at least two genes related to biofilm formation, and the ica and fnb genes were the most frequently detected genes. Three SCC mec types and seven sequence types (STs) were found in Henan, and two SCC mec types and six STs were found in Chongqing. ST239-SCC mec III was the main epidemic clone in the two hospitals., Conclusion: The resistance phenotype and molecular characteristics of S. aureus strains varied in different hospitals. The results reflect the potential risks of S. aureus infection in postoperative arthroplasty patients. Our study provides a powerful basis for the clinical treatment, infection control and monitoring of outbreaks of epidemic strains.

Purpose: Pseudomonas aeruginosa is commonly found in suppurative perichondritis, but the significant pathogens in non-abscess perichondritis are unclarified. We aimed to explore the bacterial findings and evaluate the effectiveness of different antibiotic regimes in the treatment of patients with perichondritis., Methods: All patients treated for perichondritis at the two Ear-Nose-Throat Departments in Central Denmark Region (covering 20% of the Danish population) from January 1990 to October 2018 were included., Results: In total, 112 patients with (n = 12) or without (n = 100) abscess were included in the study. Potential pathogens were found in 40 of 55 cultures. P. aeruginosa was recovered in 58% of abscess cases, while Staphylococcus aureus was predominant in non-abscess infections (49%). Eighty-two percent of S. aureus recovered were isolated as heavy or moderate growth. In non-abscess cases, no significant differences in clinical progress (p = 0.65), alteration in antibiotic therapy (p = 0.31), duration of hospitalization (p = 0.65), or frequency of relapse of infection (p = 1.00) or sequelae (p = 0.38) were found between patients treated with antibiotics covering S. aureus vs. P. aeruginosa., Conclusions: Our findings suggest that intravenous antibiotic therapy covering S. aureus is sufficient and appropriate empirical treatment in the majority of patients with non-abscess perichondritis. Antibiotic coverage should be expanded to include P. aeruginosa if the clinical response is disappointing or cultures grow P. aeruginosa. The risks and downsides to this approach seems limited as only a minority of patients suffered (minor) cosmetic sequelae and relapse of infection in our cohort of non-abscess perichondritis patients initially treated with antibiotics not covering P. aeruginosa.

Central nervous system (CNS) infections are associated with high mortality rates. The clinical presentation of many CNS infections by different pathogens is difficult to distinguish, but the definite diagnosis of the etiology is critical for effective therapy and prognosis. The aim of this study was to explore the etiology of CNS infections with definite diagnoses based on data from a clinical microbiology laboratory in Tongji Hospital, a teaching hospital in China, obtained over a six-year period. We conducted a retrospective study on all cerebrospinal fluid (CSF) specimens submitted to our clinical microbiology laboratory from September, 2012 to December, 2018. The etiology of CNS infections caused by Cryptococcus neoformans, Mycobacterium tuberculosis and common bacteria was analyzed. Antimicrobial susceptibility testing was conducted on all isolates. The results showed that 1972 cases of CNS infections were identified from 18 300 CSF specimens. Common bacterial meningitis (BM), cryptococcal meningitis (CM) and tuberculous meningitis (TM) accounted for 86.3% (677/785), 9.4% (74/785) and 4.3% (34/785) respectively of cases over the six-year period. BM was the most common among the different age groups, followed by CM. Of the TM cases, 44.1% (15/34) were distributed within the age group of 15-34 years, whereas for CM cases, 52.7% (39/74) occurred within the 35-54-year age group, and the age distribution of BM cases was fairly even. Among the bacterial pathogens isolated, Staphylococcus epidermidis was the most common, accounting for 12.5% (98/785), followed by Acinetobacter baumannii (ABA) and Staphylococcus aureus (SAU), accounting for 11.8% (93/785) and 7.6% (60/785) respectively. The resistance rates to antibiotics were >75%, with the exception of the resistance rate of ABA to tegafycline, which was <3%. More than 60% of SAU strains displayed resistance to penicillin, oxacillin, ampicillin/sulbactam, cefazolin, cefuroxime, gentamycin, tobramycin, erythromycin and levofloxacin, whereas more than 90% of SAU strains showed susceptibility to trimethoprim/sulfamethoxazole, tegafycline, vancomycin, teicoplanin and linezolid. For C. neoformans, the susceptibility rates to amphotericin B, 5-fluorocytosine, fluconazol and voriconazole were >95%. Analysis of samples from patients with CNS infection in a clinical microbiology laboratory at a teaching hospital in China over a six-year period indicated that the most common etiological agents were the bacteria ABA and SAU. The antibiotic resistance levels of ABA were found to be high and of concern, whereas isolates of C. neoformans were found to be sensitive to antifungal antibiotics.

One manner in which plant-derived compounds exert their antibiotic potential is the synergism, a positive interaction between two compounds. Studies indicate that the use of plant extracts combined with antimicrobials may promote a significant reduction of the minimum inhibitory concentrations of antibiotics for bacterial strains. This study aimed to evaluate the activity of plant extracts and antibiotics as well as their combination on Staphylococcus aureus. The activity of 15 plant extracts was evaluated using diffusion assay. The minimum inhibitory concentrations (MICs) and the interactions between the extracts and antibiotics as well as compound emodin were evaluated with the checkerboard method. The active extracts were a hexane extract of the leaves of Baccharis dracunculifolia and the ethanol extracts of the leaves of Plectranthus ornatus, Inga edulis, Salvia officinalis and Senna macranthera. The Plectranthus ornatus extract displayed synergism with ampicillin (a β-lactam), kanamycin and gentamicin (aminoglycosides), with 8-fold reductions in the MIC. The same reduction was observed for the extracts of Salvia officinalis and Senna macranthera, which displayed the lowest MIC. Using these combinations resulted in a reduction in the minimum dose required for effective antimicrobial effects, which is interesting because it may decrease both the risk of side effects and the costs of treatment.

Background: Peritoneal dialysis (PD) related infections are associated with technique failure and mortality. The aim of this multicentre study was to examine epidemiology, treatment and outcomes of PD-related infections in Poland as well as practice patterns for prevention of these complications in the context of current ISPD recommendations., Methods: A survey on PD practices in relation to infectious complications was conducted in 11 large Polish PD centres. Epidemiology of peritonitis and exit-site infections (ESI) was examined in all patients treated in these units over a 2 year period., Results: The study included data on 559 PD patients with 62.4% on CAPD. Practice patterns for prevention of infectious complications are presented. The rate of peritonitis was 0.29 episodes per year at risk, with Gram positive microorganisms responsible for more than 50% of infections and 85.8% effectively treated. Diagnosis and treatment followed ISPD guidelines however most units did not provide an anti-fungal prophylaxis. Although neither of the centres reported routine topical mupirocin on catheter exit-site, the rate of ESI was low (0.1 episodes per year at risk), with Staphylococcus aureus as most common pathogen and full recovery in 78.3% of cases., Conclusion: The study shows rewarding outcomes in prevention and treatment of PD-associated infections, mainly due to a thorough compliance with the current ISPD guidelines, although some deviations from the recommendations in terms of practice patterns have been observed. More studies are needed in large numbers of patients to differentiate the importance of specific recommendations and further support the guidelines.

The Staphylococcus aureus biofilm-associated burden is challenging to the field of medicine to eradicate or avoid it. Even though a number of S. aureus biofilm mechanisms understood and established the possible ways of biofilm formation but, still need to know more and require a development of new therapeutic strategies. In this viewpoint, we discuss the underlining biofilm mechanism, its existing systems as active therapeutic agents and as vehicles to transport drugs to the site of infection. The step-back in drug development is due to the emergence of antibiotic-resistant S. aureus. The understanding of bacteria/biofilms is an aspect that we likewise summarize for possible drug development for future as medicine against resistant S. aureus was viewed., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Objective: To examine the timing and microbiology of neonatal sepsis in a population-based surveillance in the Indian community setting., Study Design: All live born infants in 223 villages of Odisha state were followed at home for 60 days. Suspect sepsis cases were referred to study hospitals for further evaluation including blood culture., Results: Of 12 622 births, 842 were admitted with suspected sepsis of whom 95% were 4 to 60 days old. Culture-confirmed incidence of sepsis was 6.7/1000 births with 51% Gram negatives (Klebsiella predominating) and 26% Gram positives (mostly Staphylococcus aureus). A very high level of resistance to penicillin and ampicillin, moderate resistance to cephalosporins and extremely low resistance to Gentamicin and Amikacin was observed., Conclusion: The bacterial burden of sepsis in the Indian community is not high. Judicious choice of empiric antibiotics, antibiotic stewardship and alternate modalities should be considered for the management or prevention of neonatal sepsis in India.

The objective of the present study was to determine the antimicrobial resistance profile of planktonic and biofilm cells of Staphylococcus aureus and coagulase-negative staphylococci (CoNS). Two hundred Staphylococcus spp. strains were studied, including 50 S. aureus and 150 CoNS strains (50 S. epidermidis, 20 S. haemolyticus, 20 S. warneri, 20 S. hominis, 20 S. lugdunensis, and 20 S. saprophyticus). Biofilm formation was investigated by adherence to polystyrene plates. Positive strains were submitted to the broth microdilution method to determine the minimum inhibitory concentration (MIC) for planktonic and biofilm cells and the minimal bactericidal concentration for biofilm cells (MBCB). Forty-nine Staphylococcus spp. strains (14 S. aureus, 13 S. epidermidis, 13 S. saprophyticus, 3 S. haemolyticus, 1 S. hominis, 3 S. warneri, and 2 S. lugdunensis) were biofilm producers. These isolates were evaluated regarding their resistance profile. Determination of planktonic cell MIC identified three (21.4%) S. aureus strains that were resistant to oxacillin and six (42.8%) that were resistant to erythromycin. Among the CoNS, 31 (88.6%) strains were resistant to oxacillin, 14 (40%) to erythromycin, 18 (51.4%) to gentamicin, and 8 (22.8%) to sulfamethoxazole/trimethoprim. None of the planktonic isolates were resistant to vancomycin or linezolid. MICs were 2-, 4-, 8-, and up to 16-fold higher for biofilm cells than for planktonic cells. This observation was more common for vancomycin and erythromycin. The MBCB ranged from 8 to >256 µg/mL for oxacillin, 128 to >128 µg/mL for vancomycin, 256 to >256 µg/mL for erythromycin and gentamicin, >64 µg/mL for linezolid, and 32/608 to >32/608 µg/mL for sulfamethoxazole/trimethoprim. The results showed considerably higher MICs for S. aureus and CoNS biofilm cells compared to planktonic cells. Analysis of MBCM confirmed that even high concentrations of vancomycin were unable to eliminate the biofilms of S. aureus and CoNS species. Linezolid was the most effective drug in inhibiting staphylococci in the biofilm, without an increase in the MIC, when compared to planktonic cells. None of the isolates were resistant to this drug., Competing Interests: The authors declare no conflict of interest.

Aim: Study the spectrum of resistance to antibiotics and its variability of Staphylococcus aureus, Pseudomonas aeruginosa and Burkholderia cepacia complex (BCC), persisting in lungs of MV patients., Materials and Methods: 312 strains of S. aureus, 213 strains of P. aeruginosa, 186 strains of BCC were studied. Monitoring of antibiotics sensitivity was carried out in strains, isolated from 30 patients with chronic S. aureus infection, from 22 patients with chronic BCC infection and from 21 patients with chronic pseudomonas infection. Interval of monitoring was from 14 days to 5 years 7 months., Results: Study of S. aureus, P. aeruginosa and BCC strains has shown, that 35 and 33.3% of cases of staphylococcus infection, 37 and 46% of pseudomonas infection in children and adults, respectively, 100% of BCC infections were determined by multi-resistant clones. Study of genotypically identical strains, isolated from a single patient at different stages, has shown a change in antibiotics sensitivity as a result of persistence., Conclusion: Persisent infection of lungs in patients with MV is determined: by exchanging clones with varying antibiotics sensitivity or prolonged circulation of a single clone with a high degree of phenotypical and genotypical variability, that determine alteration of seeding of sensitive and resistant strains from the same patient during monitoring. This confirms the necessity of study of antibiotics sensitivity of strains for prescription of antibacterial therapy.

Introduction: Patients undergoing chronic hemodialysis using tunneled cuffed catheters (TCCs) are at increased risk of metastatic infections, namely endocarditis and spondydodiscitis, and mortality is high in this group. The aim of this study was to determine the clinical features, causative organisms, its susceptibility and outcomes in patients hospitalized with these infections from a single center., Methods: All consecutive patients with TCC and endocarditis and/or spondylodiscitis treated at the authors' institution between 2005 and 2011 were selected retrospectively., Results: A total of 7 cases of endocarditis and 7 cases of spondylodiscitis were diagnosed. Concurrent infection was present in 1 patient. The mean age was 63.4 years, 53.8% were male, 23% had diabetes and 31% had previous immunosuppression. The average time on hemodialysis was 24 months. Those patients with endocarditis presented with fever, and 43% had previous valvular disease; mitral valve involvement was the most common. Early surgery was performed in 2 patients.Concerning spondylodiscitis, the median time from first symptom to diagnosis was 48 days. The first manifestation was back pain in 86% percent of patients, and 71% had an epidural or paraspinous abscess demonstrated by neuroimaging. One patient underwent surgical drainage of the abscess. Regarding both infections, staphylococcus aureus was the most common causative agent with a lower rate of negative blood cultures. All patients received intravenous antibiotics for a mean duration of six weeks. The mortality rate was 46%., Conclusions: A high index of suspicion is critical in the early recognition and management of both of these infections.

Objective: The purpose of this study was to estimate the incidence of deep periprosthetic joint infections (PJIs) after primary total hip replacement (THR) in Sweden prior to the introduction of a national initiative to reduce these infections., Design: Prospective open cohort study with 2 years follow-up of each subject., Setting: All THR-performing clinics in Sweden., Methods: All patients registered for a primary THR in the Swedish Hip Arthroplasty Register between July 1, 2005, and December 31, 2008, were selected for the study (45,531 patients with 49,219 THRs) and were matched with the Swedish Prescribed Drug Register. All patients with a minimum of 4 weeks of continuous outpatient antibiotic treatment within 2 years after their primary THR (1,989 patients with 2,219 THRs) were selected for a medical records review, and the number of cases with PJI was determined., Results: The cumulative incidence of PJI within 2 years after primary THR was 0.9% (95% confidence interval, 0.85-1.02; n = 443), and 405 of these had been reoperated. The incidence rate of PJI for the first 3 months was 5 per 10,000 THR-weeks and, thereafter, 0.3 per 10,000 THR-weeks. Staphylococcus aureus and coagulase-negative staphylococci were the most common bacteria isolated., Conclusions: This study describes a new method of national postoperative infection surveillance. The incidence is similar to previous smaller reports and is useful for monitoring changes over time to evaluate the national initiative to reduce infections.

Background: Ventilator-associated pneumonia (VAP) is classified as early-onset or late-onset, in part, to identify subjects at risk for infection with resistant pathogens. We assessed differences in the bacterial etiology of early-onset versus late-onset VAP., Methods: Subjects enrolled in 2004-2006 in 2 clinical studies of doripenem versus imipenem or piperacillin/tazobactam, with a diagnosis of VAP (n = 500) were included in the analysis. Subjects were classified by ventilator status: early-onset VAP (< 5 d of ventilation) or late-onset VAP (≥ 5 d of ventilation). Baseline demographics and bacterial etiology were analyzed by VAP status., Results: Late-onset VAP subjects had higher Acute Physiology and Chronic Health Evaluation (APACHE II) scores (mean 16.6 versus 15.5, P = .008). There were no significant differences in Clinical Pulmonary Infection Score, sex, age, or presence of bacteremia between the groups. A total of 496 subjects had a baseline pathogen, and 50% of subjects in each group had ≥ 2 pathogens. With the exception of Staphylococcus aureus, which was common in early-onset VAP, the pathogens (including potentially multidrug-resistant (MDR) pathogens) isolated from early-onset versus late-onset VAP were not significantly different between groups. Acinetobacter baumannii or Pseudomonas aeruginosa with decreased susceptibility to any study drug was observed in early-onset and late-onset VAP subjects., Conclusions: There were no significant differences in the prevalence of potential MDR pathogens associated with early-onset or late-onset VAP, even in subjects with prior antibiotics. Empiric therapy for early-onset VAP should also include agents likely to be effective for potential MDR pathogens. Further prospective studies should evaluate microbiology trends in subjects with VAP.

Rhinoscleroma is a chronic indolent granulomatous infection of the nose and the upper respiratory tract caused by Klebsiella rhinoscleromatis; this condition is endemic to many regions of the world including North Africa. We present a case of rhinoscleroma in a 51-year-old Egyptian immigrant with 1-month history of epistaxis. We would postulate that with increased travel from areas where rhinoscleroma is endemic to other non-endemic areas, diagnosis of this condition will become more common., (© 2012 International Society of Travel Medicine.)

Community-acquired strains of methicillin-resistant Staphylococcus aureus (MRSA) have become a common cause of skin and soft tissue infections in the United States. These infections sometimes require treatment with antibiotics, and with the increasing resistance of pathogens to these agents, choosing the appropriate drug can be difficult. In lactating women who develop these infections, selecting an antibiotic is even more challenging, as clinicians need to be aware of risks to the infant from the drug excreted during lactation. To our knowledge, no review has addressed the safety of antibiotics in breastfeeding infants when the drugs are used to treat maternal skin and soft tissue infections from MRSA. Thus, we performed a literature search of the PubMed-MEDLINE and EMBASE databases (1974-March 2009), reviewed reference citations from identified publications, researched antibiotic prescribing information, and corresponded with drug manufacturers. Case reports, case series, and both in vivo and in vitro clinical trials were evaluated for the following antibiotics: clindamycin, daptomycin, linezolid, quinupristin-dalfopristin, rifampin, tetracycline, doxycycline, minocycline, tigecycline, trimethoprim-sulfamethoxazole, and vancomycin. Information for the newer antibiotics (linezolid, quinupristin-dalfopristin, tigecycline, and daptomycin) was limited. Despite heterogeneity in the data for the older antibiotics (clindamycin, rifampin, tetracyclines, trimethoprim-sulfamethoxazole, and vancomycin), all appear to be relatively safe in the minimal quantities nursing infants ingest through breast milk. Although the risk to infants seems to be relatively low for most of the agents we explored, the paucity of data indicates a need for close monitoring of breastfed infants whose mothers are receiving an antibiotic for an MRSA skin and soft tissue infection.

How do antibiotics actually work? Although the primary cellular targets of many antimicrobial agents have been identified, the downstream events leading to bacterial cell death remain unclear. In this issue, Kohanski et al. (2007) provide evidence that the production of reactive oxygen species is a shared mechanism of cell death initiated by bactericidal antibiotics.

Antibiotic mode-of-action classification is based upon drug-target interaction and whether the resultant inhibition of cellular function is lethal to bacteria. Here we show that the three major classes of bactericidal antibiotics, regardless of drug-target interaction, stimulate the production of highly deleterious hydroxyl radicals in Gram-negative and Gram-positive bacteria, which ultimately contribute to cell death. We also show, in contrast, that bacteriostatic drugs do not produce hydroxyl radicals. We demonstrate that the mechanism of hydroxyl radical formation induced by bactericidal antibiotics is the end product of an oxidative damage cellular death pathway involving the tricarboxylic acid cycle, a transient depletion of NADH, destabilization of iron-sulfur clusters, and stimulation of the Fenton reaction. Our results suggest that all three major classes of bactericidal drugs can be potentiated by targeting bacterial systems that remediate hydroxyl radical damage, including proteins involved in triggering the DNA damage response, e.g., RecA.

S. pneumoniae and methicillin-resistant S. aureus are the main Gram-positive pathogens responsible for severe infections. In the context of community infections S. pneumoniae is the leading Gram-positive pathogen causing severe infections such as purulent meningitis and pneumonia. The typical pattern of antibiotic sensitivity of this bacterium, frequently resistant to macrolides and with significantly reduced sensitivity to penicillin, is only a relative therapeutic problem in that the preserved sensitivity to third-generation cephalosporins and respiratory fluoroquinolones is sufficient to make these antibiotics valid therapeutic solutions without having to use the latest generation of drugs. On the other hand, methicillin-resistant S. aureus, one of the main bacteria responsible for nosocomial infections such as bacteraemia and respiratory tract infections in severely ill patients, is a more challenging therapeutic problem since, historically, the therapeutic options available in clinical practice have been fewer and essentially limited to glycopeptides. The recent availability of oxazolidinones and the pharmacologically more rational and appropriate use of the glycopeptides have undoubtedly brought substantial benefits; the imminent introduction of new molecules active against Gram-positive pathogens will certainly make an important contribution, although their use in clinical practice will need to be monitored.

In this investigation, metabolic profiles of Staphylococcus aureus treated by berberine and nine antibacterial substances with known modes of action were acquired by HPLC/ESI-MS. After data pretreatment, those profiles acquired were reduced into several MS vectors. Then, principal component analysis was carried out upon those vectors to classify those drugs according to their mechanisms. From the result obtained by principal component analysis, the possible antibacterial mode of berberine was evaluated.

This article compares vancomycin, teicoplanin, quinupristin-dalfopristin, linezolid, daptomycin, tigecyline, dalbavancin, telavancin, ceftobiprole, oritavancin, and ramoplanin for the treatment of complicated skin and skin structure infections (cSSSI), methicillin-resistant Staphylococcus aureus (MRSA), enterococcus, and vancomycin-resistant enterococcus. Vancomycin, a glycopeptide antibiotic, is administered intravenously, and is the mainstay of treatment for MRSA and cSSSI. While not available in the U.S., teicoplanin, another glycopeptide antibiotic, can be administered intramuscularly and has simpler dosing and monitoring requirements than vancomycin. Quinupristin/dalfopristin treats vancomycin-resistant Enterococcus faecium (VREF) infections but inhibits cytochrome P450 A3P4, and has only modest activity against MRSA pneumonia. Daptomycin effectively treats cSSSI but not pneumonia caused by MRSA, and is effective against all strains of Staphylococcus. Linezolid, available orally and intravenously, is approved to treat community-acquired and nosocomial pneumonia, cSSSI, and infections caused by MRSA and vancomycin-resistant enterococci including infections with concurrent bacteraemia and VREE Tigecycline, a glycylcycline derived from minocycline, has been approved by the FDA to treat cSSSI and complicated intraabdominal infections, and might be effective against Acinetobacter baumannii; its primary side effect is digestive upset. Dalbavancin, effective against MRSA and administered intravenously once weekly, possesses coverage similar to vancomycin. Telavancin deploys multiple mechanisms of action and is effective against MRSA and Gram-positive bacteria resistant to vancomycin. Ceftobiprole, a cephalosporin effective against MRSA, has few side effects. Oritavancin demonstrates similar activity to vancomycin but possesses extended activity against vancomycin-resistant Staphylococcus and enterococci. Ramoplanin, a macrocyclic depsipeptide, is unstable in the bloodstream but can be taken orally to treat Clostridium difficile colitis.

The RNA polymerase holoenzyme is a proven target for antibacterial agents. A high-throughput screening program based on this enzyme from Staphylococcus aureus had previously identified a 2-ureidothiophene-3-carboxylate as a low micromolar inhibitor. An investigation of the relationships between the structures of this class of compounds and their inhibitory- and antibacterial activities is described here, leading to a set of potent RNA polymerase inhibitors with antibacterial activity. Characterization of this bioactivity, including studies of the mechanism of action, is provided, highlighting the power of the reverse chemical genetics approach in providing tools to inhibit the bacterial RNA polymerase.

A novel multidrug resistance phenotype mediated by the Cfr rRNA methyltransferase is observed in Staphylococcus aureus and Escherichia coli. The cfr gene has previously been identified as a phenicol and lincosamide resistance gene on plasmids isolated from Staphylococcus spp. of animal origin and recently shown to encode a methyltransferase that modifies 23S rRNA at A2503. Antimicrobial susceptibility testing shows that S. aureus and E. coli strains expressing the cfr gene exhibit elevated MICs to a number of chemically unrelated drugs. The phenotype is named PhLOPSA for resistance to the following drug classes: Phenicols, Lincosamides, Oxazolidinones, Pleuromutilins, and Streptogramin A antibiotics. Each of these five drug classes contains important antimicrobial agents that are currently used in human and/or veterinary medicine. We find that binding of the PhLOPSA drugs, which bind to overlapping sites at the peptidyl transferase center that abut nucleotide A2503, is perturbed upon Cfr-mediated methylation. Decreased drug binding to Cfr-methylated ribosomes has been confirmed by footprinting analysis. No other rRNA methyltransferase is known to confer resistance to five chemically distinct classes of antimicrobials. In addition, the findings described in this study represent the first report of a gene conferring transferable resistance to pleuromutilins and oxazolidinones.

The pharmacodynamic properties governing the activities of antibiotics against intracellular Staphylococcus aureus are still largely undetermined. Sixteen antibiotics of seven different pharmacological classes (azithromycin and telithromycin [macrolides]; gentamicin [an aminoglycoside]; linezolid [an oxazolidinone]; penicillin V, nafcillin, ampicillin, and oxacillin [beta-lactams]; teicoplanin, vancomycin, and oritavancin [glycopeptides]; rifampin [an ansamycin]; and ciprofloxacin, levofloxacin, garenoxacin, and moxifloxacin [quinolones]) have been examined for their activities against S. aureus (ATCC 25923) in human THP-1 macrophages (intracellular) versus that in culture medium (extracellular) by using a 0- to 24-h exposure time and a wide range of extracellular concentrations (including the range of the MIC to the maximum concentration in serum [C(max); total drug] of humans). All molecules except the macrolides caused a net reduction in bacterial counts that was time and concentration/MIC ratio dependent (four molecules tested in detail [gentamicin, oxacillin, moxifloxacin, and oritavancin] showed typical sigmoidal dose-response curves at 24 h). Maximal intracellular activities remained consistently lower than extracellular activities, irrespective of the level of drug accumulation and of the pharmacological class. Relative potencies (50% effective concentration or at a fixed extracellular concentration/MIC ratio) were also decreased, but to different extents. At an extracellular concentration corresponding to their C(max)s (total drug) in humans, only oxacillin, levofloxacin, garenoxacin, moxifloxacin, and oritavancin had truly intracellular bactericidal effects (2-log decrease or more, as defined by the Clinical and Laboratory Standards Institute guidelines). The intracellular activities of antibiotics against S. aureus (i) are critically dependent upon their extracellular concentrations and the duration of cell exposure (within the 0- to 24-h time frame) to antibiotics and (ii) are always lower than those that can be observed extracellularly. This model may help in rationalizing the choice of antibiotic for the treatment of S. aureus intracellular infections.

Culture-based values for antimicrobial susceptibility of 28 antimicrobials against different bacteria isolated from clinical material in a tertiary care hospital were used to pick the most promising antimicrobials. Isolates originating from urinary tract, blood and pyogenic foci, enteric fever and enteritis were grouped. Antimicrobials, systemic or oral, exhibiting a 75% or more susceptibility were compartmentalized in relation to divergent clinical disorders. Retrospective categorized culture-based susceptibility values should help a rational prospective chemotherapeutic intervention against infectious syndromes encountered in hospital practice.

The objective of our study was to investigate the relationship between molecular epidemiology and antibiotic susceptibility of MRSA during a four-year period. In this aim, we determined the antibiotype of all MRSA identified during a yearly period of 3 months and typed 50 consecutive non-replicate MRSA isolates of each year. We also recorded antibiotic use. Susceptibility rates to gentamicin, tobramycin and ofloxacin remained stable, respectively, 95, 16 and 4%. In contrast, the proportion of MRSA susceptible to erythromycin progressively increased from 7.0% to 32.5% (P < 0.001). PFGE analysis of genomic DNA from the 200 isolates revealed 15 different clones. We identified two epidemic clones, which contained 150 (clone A) and 28 isolates (clone C), respectively. The proportion of isolates belonging to clone A decreased during the study from 86% to 66%. Conversely, clone C increased from 4% to 22%. The increase of erythromycin-susceptibility within MRSA was caused by the emergence of clone C. Non-epidemic strains were more frequently susceptible to ofloxacin (31.8% vs. 1.1%) and tobramycin (45.4% vs. 16.8%) than epidemic strains. Antimicrobial use had not significantly varied during the study. The proportion of beta-lactams, fluoroquinolones, macrolides and aminosides was 71.8, 13.9, 5.0 and 3.8% of the total antibiotic use, respectively. In our hospital, MRSA isolates became more susceptible to antimicrobial of minor use. The selection pressure exerted by beta-lactams and fluoroquinolones was in favor of the spread of strains resistant to these both major antibiotic classes.

Histidine-free variants of salivary histatin 5 have a broad antimicrobial activity against various bacteria. In relation to a possible therapeutic application, we were interested in the susceptibility of these small peptides (14 amino acids long) to microbial proteinases and whether this affects their antimicrobial activity. Analyses by SDS-PAGE of supernatants of peptide-bacteria incubation showed a reduction in protein bands within 15 minutes' incubation, as a result of cellular internalization. Degradation products of dhvar1 and dhvar2 appeared within one hour in the supernatants of Streptococcus mutans and Staphylococcus aureus. In contrast, the variants dhvar3 and dhvar4 were more resistant to degradation under the same conditions. MALDI-TOF analyses identified cleavage of dhvar1 and dhvar2 at Glu(6). The N-terminal peptide part (1-6) of dhvar1 and 2 showed no bactericidal activity, while peptide fragment (7-14) showed a highly reduced bactericidal activity.

Purpose of Review: The concept of methicillin-resistant Staphylococcus aureus (MRSA) associated with broad resistance, nosocomial acquisition, and known risk factors has recently been expanded. A new type of MRSA that is resistant to fewer antibiotics has emerged in pediatric practice since the mid-1990s. These isolates are community acquired and have been reported from diverse geographic regions. Awareness of these organisms is important for appropriate treatment of S. aureus infections in children., Recent Findings: Community-acquired MRSA (CA-MRSA) isolates are similar in many respects to community-acquired methicillin-susceptible S. aureus (CA-MSSA). There are usually no differences in risk factors between children with CA-MRSA infections and those with CA-MSSA infections or their household contacts. In one study, however, multivariate analysis showed that age greater than 1 year and health care contact in the preceding month were significant risk factors for CA-MRSA. Skin and soft tissue infections are the most common manifestations, although serious invasive infections and death may occur. Pneumonia has been reported more often in children with CA-MRSA than in those with CA-MSSA. Clindamycin is an effective therapy for CA-MRSA, but there is a risk for development of clindamycin resistance during treatment of a CA-MRSA that is clindamycin susceptible and inducibly erythromycin resistant. Trimethoprim-sulfamethoxazole is likely to be effective, and linezolid is a new option for treatment., Summary: The appearance of CA-MRSA has important implications for therapy of infections caused by S. aureus in children. Three specific issues are the development of resistance during clindamycin therapy, insufficient data on the use of trimethoprim-sulfamethoxazole in serious CA-MRSA infections, and the appropriate role for newer antibiotics such as linezolid.

We have reported that the gene mph(C) (formally referred to as 'mphBM') is located on plasmid pMS97 342 bp downstream of the msr(A) gene. msr(A) specifies resistance to macrolides by ABC-transporter-mediated efflux, and mph(C) has 49% identity to the amino acid sequence of MPH(2')II, which encodes a phosphotransferase that inactivates some macrolide antibiotics. A strain of Staphylococcus aureus NCTC8325 containing plasmid pMS97 inactivated unlabeled and (14)C-labeled erythromycin when tested by bioautographic and radioautographic techniques. In addition to erythromycin, other 14-membered ring macrolides (except for ketolides), 15-membered ring macrolides and 16-membered ring macrolides, mycinamicin, rosamicin and YM133, were inactivated by the strain. Erythromycin inactivation products produced by the strain carrying pMS97 were completely different from those produced by Escherichia coli BM694 bearing plasmid pAT63, which contains the ereA gene encoding an esterase that hydrolyzes macrolide lactones. Constructs formed with the msr(A) and mph(C) genes, and with the msr(A), mph(C) and erm(Y) genes, showed erythromycin-inactivating activity, but another construct built with the mph(C) gene alone failed to show such activity. This result suggests that any region of the msr(A) gene is needed for the expression of mph(C).

The activity of linezolid, a new oxazolidinone, was tested against 862 Gram-positive cocci isolated in Italy and compared with the activities of 12 antibiotics. Overall, MIC90s for linezolid (2-4 mg/L) indicated an in vitro activity comparable to that of vancomycin in methicillin-resistant Staphylococcus aureus (4 mg/L), S. epidermidis (2 mg/L) and methicillin-susceptible strains. Enterococcus faecalis strains were susceptible to linezolid (MIC90 2-4 mg/L), glycopeptides and beta-lactams. In E. faecium, only glycopeptides (MIC90 2 mg/L) and linezolid (MIC90 2 mg/L) were active. Linezolid was the only drug active against two strains of Enterococcus showing a VanA phenotype. Owing to its antibacterial profile, linezolid represents a promising drug for the treatment of Gram-positive infections.

We examined drug-resistance patterns, coagulase types, and MRSA-phage types of 125 MRSA strains isolated from clinical specimens during the period of January 1990 and December 1994. No vancomycin-resistant strain was isolated. Twenty one antibiotics were divided into three classes, low-intermediate- and high-isolation-frequency class, based on isolation frequencies of resistant strains. Minocycline, chloramphenicol, streptomycin, and imipenem were found to be included in low-isolation-frequency class (16.8-40%). In intermediate-isolation-frequency class (45.6-62.9%), cefmetazole, amikacin, gentamicin, and tetracycline were included. Oxacillin, ampicillin, piperacillin, ceftizoxime, cefoperazone, cefazolin, erythromycin, oleandomycin, kitasamycin, clindamycin, kanamycin, tobramycin, and ofloxacin belonged to high-isolation-frequency class (97.6-100%). MIC90s of vancomycin and minocycline (1.56 and 25 micrograms/ml) were lower than that of other 13 drugs. Comparing medical ward with dental ward, imipenem-, gentamicin-, and minocycline-resistant strains at medical ward, chloramphenicol- and streptomycin-resistant strains at dental ward were isolated dominantly on each ward, MRSA isolates were classified to 39 types by drug-resistance patterns. The isolation frequencies of coagulase type II and type IV strains were 65.6% and 29.6%, respectively. At dental ward, the isolation frequency of coagulase type IV strains was higher than that of coagulase type II strains during 1990-1992. However, coagulase type II strains were isolated considerably more than type IV strains during 1993-1994. By MRSA-phage typing, MRSA isolates were grouped into 18 MRSA-phage types. One hundred and twenty five MRSA isolates were divided into 56 types by using drug-resistance patterns, coagulase typing, and MRSA-phage typing. It was considered that such classification in combination of three methods is useful to make decision of epidemic by the same MRSA strain.

The cross-resistance between the aminoglycoside antibiotics, gentamycin, tobramycin, kanamycin and streptomycin was tested using clinical isolates of Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus obtained from Ahmadu Bello University Teaching Hospital Zaria, Nigeria (ABUTH). The antibiotics can be classified into two groups: the kanamycin and streptomycin group on one hand to which isolates easily acquired resistance, and the amikacin, gentamycin and tobramycin group on the other to which the isolates did not easily develop resistance. There seems not to be any hard and fast rule that can be applied to the cross-resistance between these aminoglycoside antibiotics. The isolates varied markedly in their pattern of cross-resistance towards the different antibiotics.

Five types of ear drops were each assessed for effectiveness on the basis of the in vitro antibacterial activity. Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), and Pseudomonas aeruginosa isolated from purulent otitis media were evaluated by comparative analysis. Otic drops containing new fluorinated quinolones, Ofloxacin and NY-198, showed high in vitro activity against all the bacteria. Cortisporin expressed moderate activity against P. aeruginosa and relatively weak activity against S. aureus and MRSA. Bestron and Fosmicin possessed low activity against three clinical isolates. Otic drops containing the new quinolones may be effective for treating purulent otitis media infected by MRSA and P. aeruginosa.

Over a 14 year period, there were 20 patients who presented with staphylococcal empyema from whom methicillin-resistant Staphylococcus aureus (MRSA) was isolated. Twelve cases were community-acquired and 8 were hospital-acquired infections. Patients were treated with penicillinase-resistant penicillin, cephalosporin or carbapenem in combination with or without aminoglycoside. They were also treated with drainage or thoracentesis. However, they were refractory to treatment and 7 patients, 6 of whom were suffering from bacteremia, died. One bacteremic patient was treated with vancomycin and was cured. In an area of endemic MRSA, vancomycin may be the first choice in the initial treatment of staphylococcal empyema until antimicrobial susceptibility can be determined.