Differences in MRSA prevalence and resistance patterns in a tertiary center before and after joining an international program for surveillance of antimicrobial resistance.

Methicillin-resistant Staphylococcus aureus (MRSA) emerged as one of the most important causes of hospital-acquired bloodstream infections (BSIs), especially the multidrug resistant clones. The aim of the present study was to compare prevalence and resistance patterns of MRSA bacteremia in the major tertiary-care academic and referral center in Serbia before and after implementing an active antimicrobial resistance (AMR) surveillance. Laboratory-based before-after study was conducted during a two-year period (January 2012 to December 2013) in Clinical Centre of Serbia. Isolation and identification of bacterial strains were done following standard microbiological procedures. During the AMR surveillance, nearly twice more bloodstream samples were collected compared to the year without surveillance (1,528 vs. 855). In total, 43 isolates of MRSA were identified. MRSA was significantly more prevalent during the AMR surveillance compared to the previous year [14 (66.7%) to 29 (76.3%); P = 0.046]. During the AMR surveillance, MRSA more frequently originated from medical departments compared to intensive care unit, surgical department, and internal medicine (P = 0.027) indicating increasing MRSA infections in patients with less severe clinical condition and no apparent risk factors. Higher prevalence of MRSA and its lower susceptibility to erythromycin were revealed by implementation of active AMR surveillance, which may reflect more thoughtful collection of bloodstream samples from patients with suspected BSI.

Antimicrobial resistance of selected invasive bacteria in a tertiary care center: results of a prospective surveillance study.

INTRODUCTION: We aimed to report the distribution and resistance patterns of eight invasive clinically relevant bacteria surveyed in the Clinical Center of Serbia (CCS) in Belgrade. METHODOLOGY: A total of 477 clinical blood stream isolates of Staphylococcus aureus, Streptococcus pneumoniae, Enterococcus faecium, Enterococcus faecalis, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter spp. were collected in the period from January to December 2013. Antimicrobial susceptibility testing was performed using standard methods and interpreted using the Clinical and Laboratory Standards Institute (CLSI) breakpoint criteria. RESULTS: Acinetobacter spp. was the most prevalent bacteria encountered (37%), followed by K. pneumoniae (25.7%). Multidrug resistance was observed in 92.5% of all isolates. Out of 177 strains of Acinetobacter spp., 97.7% were resistant to fluoroquinolones and carbapenems. Resistance to aminoglycosides, fluoroquinolones, and third-generation cephalosporins was 97.1%, 95.4%, and 95.8% among K. pneumoniae and 21.4%, 21.7%, and 31% among E. coli isolates, respectively. In total, 65.1% of K. pneumoniae and 12.1% of E. coli isolates were determined to be extended-spectrum beta-lactamase (ESBL) positive. High-level aminoglycoside resistance of E. faecalis was 71.4%, and glycopeptide resistance of E. faecium was 95%. Out of 66 strains of S. aureus, 63.4% were methicillin resistant. CONCLUSIONS: The majority of bloodstream isolates of clinically relevant bacteria in CCS were multidrug resistant. The biggest concerns are carbapenem-resistant Acinetobacter spp., K. pneumoniae, and P. aeruginosa; third-generation cephalosporin-resistant E. coli; vancomycin-resistant E. faecium; and methicillin-resistant S. aureus. Stricter measures of infection control and antibiotic use are needed.

Molecular characterization of vancomycin-resistant enterococci in Serbia: intensive care unit as the source.

The purpose of this study was to evaluate the molecular relatedness of clinical isolates of vancomycin-resistant enterococci (VRE) collected from patients of the Clinic for Infectious and Tropical Diseases in Belgrade. Among 40 isolates available for the investigation, 36 were identified as Enterococcus faecium, whereas 2 were Enterococcus faecalis and Enterococcus raffinosus, respectively. Pulsed-field gel electrophoresis (PFGE) typing revealed 21 strain types, comprising 7 clusters which contained at least two isolates and 14 unique PFGE patterns. Although we searched for pathogenicity factor genes (gelE, cylB, asa1, efaAfs, esp, cpd, cob) in representatives of all macro-restriction patterns, they have been confirmed in only one clone of E. faecalis. Genes esp and hyl, commonly found in E. faecium, were yilded in 10 macro-restriction patterns of this species, and their presence could not be ascribed to clonally related strains (p = 0.05). All VRE isolates were multiresistant and positive for vanA gene. Twenty strains of VRE and 6 clusters obtained from Intensive care unit (ICU) are proof of intensive transmission of these microorganisms at this department. The results of this study suggest wide genotypic variability among the clinical VRE isolates, but also intrahospital dissemination of some of them.