EPIDEMIOLOGY Characteristics of Vancomycin-Resistant Enterococcus Strains in the West Balkans: A First Report Sanja Jakovac, 1 Elma Feric ´ Bojic ´, 2 Monia Avdic ´ Ibris ˇimovic ´, 2 Borka Tutis ˇ, 1 Maja Ostojic ´, 1 and Mirsada Hukic ´ 2–4 Vancomycin-resistant enterococci are among the major causes of nosocomial infections and represent a growing problem in many European countries. Among the most common enterococcal isolates, Enterococcus faecium is considered to be the reservoir of VanA and VanB-mediated resistance to glycopeptides. Enterococci with VanA-mediated resistance can transfer resistance genes to other enterococci and gram-positive bacteria. Hence, monitoring and surveillance of vancomycin-resistant enterococci (VREs) are crucial for the prevention of the spread of glycopeptide resistance. No reports have yet been published that document the resistance rates and typization of VREs in the region of Bosnia and Herzegovina as well as Croatia. In this study, 64 clinical enterococcal strains that were isolated in clinical centers, Mostar, Sarajevo, and Zagreb, were studied and findings regarding characteristics of vancomycin-resistant strains found in the West Balkan region are reported for the first time. All of the strains were identified using conventional phenotypic methods, and the resistance to glycopeptides was determined using the disk diffusion method, Vitek 2, and genotypic Enterococcus assay. The results of genotyping showed that 40 strains were identified as VREs (30% Enterococcus faecalis and 70% E. faecium), while the sensitivity of the phenotypic methods was 87.5%. Furthermore, VanA and VanB resistance types were found in Bosnia and Herzegovina and Croatia, with slightly higher prevalence of the latter (72.5%) over the former (27.5%). Introduction V ancomycin resistance in enterococci was first re- ported in France and England, but in the 1980s, it showed the most dramatic increase in the United States, where it was attributed to the widespread use of vancomycin in hospitals. Many reports confirmed the appearance of these vancomycin-resistant enterococcus (VRE) strains in European countries as well, and according to publications by the Eu- ropean Centre for Disease Prevention and Control (ECDC), this is a growing problem. 1–3 A total of 8142 isolates with antibiotic sensitivity testing (AST) information for vancomy- cin were reported in 29 countries for 2014. 3 National resistant isolate percentages ranged from zero in countries such as Estonia, Finland, Iceland, and Malta to 45.1% in Ireland in 2014. 3 During the period from 2011 to 2014, trends were calculated for 24 countries reporting at least 20 isolates per year during all 4 years. In eight countries, namely Bulgaria, Croatia, Denmark, Hungary, Ireland, Italy, Slovakia, and United Kingdom, significantly increasing trends were ob- served. 3 While the ECDC developed a monitoring system for surveillance of various aspects of antimicrobial resistance in the countries of the European Union (EU), 4 it’s shortcoming is the fact that it does not include analyses of countries that are not part of the EU. Bosnia and Herzegovina is not included in any of the European networks responsible for antimicrobial resistance analysis and therefore the extent of antimicrobial resistance in Bosnia and Herzegovina remains entirely un- known. Infections most commonly caused by enterococci include complicated urinary tract infections, bacteremias, endocarditis, intra-abdominal and pelvic infections, wound and soft tissue infections, neonatal sepsis, and rarely meningitis. 5 The deter- mination of vancomycin resistance in enterococci conducted by genotypic and phenotypic methods to date has shown that their acquired resistance to glycopeptides corresponds to six different phenotypes, namely VanA, VanB, VanD, VanE, VanG, and VanL. Furthermore, VanC1 and VanC2/3 are responsible for the intrinsic resistance in Enterococcus gallinarum and En- terococcus casseliflavus. 6–11 The VanA phenotype was more 1 Institute for Microbiology and Molecular Diagnostics, University Clinical Hospital, Mostar, Bosnia and Herzegovina. 2 Department of Genetics and Bioengineering, International Burch University, Sarajevo, Bosnia and Herzegovina. 3 Institute for Biomedical Research and Diagnostics NALAZ, Sarajevo, Bosnia and Herzegovina. 4 Academy of Sciences and Arts of Bosnia and Herzegovina, Sarajevo, Bosnia and Herzegovina. MICROBIAL DRUG RESISTANCE Volume 00, Number 00, 2016 ª Mary Ann Liebert, Inc. DOI: 10.1089/mdr.2015.0355 1