Background:Retrospective studies have reported good clinical success rates using colistin as monotherapy to treat Acinetobacter baumannii ventilator-associated pneumonia (VAP), comparable to that obtained with colistin combined with other antibiotics. However, inadequate penetration into the pulmonary parenchyma for colistin has been shown in animal models.Aim:The aim of the study was to study prospectively the outcome, measured as clinical response and survival, of intravenously administered colistin versus colistin combined with high-dose ampicillin-sulbactam in Intensive Care Unit (ICU) patients with multiresistant A. baumannii VAP.Methods and Subjects:This prospective, open-label, randomized study included consecutive patients who developed microbiologically documented VAP due to A. baumannii with carbapenem-resistant strains but susceptible to colistin and ampicillin-sulbactam. Seventy-four patients were screened, but finally, 39 participants were enrolled and finished the study Patients received colistin (Group A – 19 patients) or colistin and ampicillin/sulbactam (Group B – 20 patients). The clinical response of VAP was assessed on day 4th to 5th of treatment (early response). If therapy was considered unsuccessful after this period, ampicillin/sulbactam was added in Group A or changed therapy in B.Results:Early cure rates in Group A and B were 15.8% and 70%, respectively (P = 0.001). Multiple regression analysis revealed that combination treatment (odds ratio [OR]: 43.6, 95% confidence interval [CI]: 3.594–530.9) and Sequential Organ Failure Assessment score <8 (OR: 0.022, 95% CI: 0.001–0.43) were independently associated with favorable clinical response. APACHE II score ≤15 (OR: 0.049, 95% CI: 0.003–0.0942) and an early favorable response to treatment (OR: 244.4, 95% CI: 2.151–27850.9) were associated with survival and discharge from ICU.Conclusion:Combination therapy with colistin and a high dose of ampicillin/sulbactam was associated with a more favorable clinical response to VAP due to carbapenem-resistant A. baumannii than colistin monotherapy.

erm(C) is the predominant genetic determinant for the expression of MLS(B) resistance among S. aureus isolates, especially MRSA, in Greece. This is due to the spread of two major clones in the country.

The distribution of the mec genes mecA, mecR1 and mecI that regulate the expression of methicillin resistance was investigated by PCR in 145 staphylococci of hospital origin. Determination of alterations and deletions in parts of the genes was achieved using 11 sets of primers in combined reactions. Methicillin-resistant Staphylococcus epidermidis strains appeared relatively stable, with 57.9% of isolates containing the whole regulatory region. Alterations within the mecA gene were detected more often in other coagulase-negative staphylococci, which also had a higher percentage with deletions of regulatory genes. Among methicillin-resistant S. aureus, a genetically heterogeneous population was identified, with several alterations and deletions of mec genes.

IntroductionIn Greece, fusidic acid and clindamycin are commonly used for the empiric therapy of suspected staphylococcal infections.MethodsThe medical records of children examined at the outpatient clinics or admitted to the pediatric wards of the University General Hospital of Larissa, Central Greece, with community-associated staphylococcal infections from January 2003 to December 2009 were reviewed.ResultsOf 309 children (0-14 years old), 21 (6.8%) had invasive infections and 288 (93.2%) skin and soft tissue infections (SSTIs). Thirty-five patients were ≤30 days of age. The proportion of staphylococcal infections caused by a community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) isolate increased from 51.5% (69 of 134) in 2003-2006 to 63.4% (111 of 175) in 2007-2009 (P = 0.037). Among the CA-MRSA isolates, 88.9% were resistant to fusidic acid, 77.6% to tetracycline, and 21.1% to clindamycin. Clindamycin resistance increased from 0% (2003) to 31.2% (2009) among the CA-MRSA isolates (P = 0.011). Over the 7-year period, an increase in multidrug-resistant CA-MRSA isolates was observed (P = 0.004). One hundred and thirty-one (93.6%) of the 140 tested MRSA isolates were Panton-Valentine leukocidin-positive. Multilocus sequence typing of 72 CA-MRSA isolates revealed that they belonged to ST80 (n = 61), ST30 (n = 6), ST377 (n = 3), ST22 (n = 1), and ST152 (n = 1). Resistance to fusidic acid was observed in ST80 (58/61), ST30 (1/6), and ST22 (1/1) isolates.ConclusionIn areas with high rate of infections caused by multidrug-resistant CA-MRSA isolates, predominantly belonging to the European ST80 clone, fusidic acid and clindamycin should be used cautiously as empiric therapy in patients with suspected severe staphylococcal infections.

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