title: Molecular characterization of macrolide resistant Streptococcus pyogenes isolates from pharyngitis patients in Serbia.
abstract: A steady increase in macrolide resistance in Streptococcus pyogenes, group A streptococci (GAS) was reported in Serbia during 2004-2009 (9.9%). However, there are no data on the molecular epidemiology of pharyngeal macrolide resistance GAS (MRGAS) isolates. Therefore, the aims of this first nationwide study were to examine the prevalence of macrolide resistance in Serbian GAS and to determine their resistance phenotypes, genotypes and clonal relationships. Overall 3893 non-duplicate pharyngeal S. pyogenes isolates from outpatients with GAS infection were collected throughout country during 2008 and 2009. Among 486 macrolide resistant pharyngeal isolates collected, 103 were further characterized. Macrolide resistance phenotypes and genotypes were determined by double-disk diffusion test and PCR, respectively. Strain relatedness was determined by emm typing, multilocus sequence typing (MLST), multilocus variable tandem repeat analysis (MLVA), phage profiling (PP) and virulence factor profiling (VFP). Overall, macrolide resistance among GAS isolates in Serbia was 12.5%. M phenotype was the most common (71.8%), followed by iMLS (18.4%) and cMLS (9.7%). Three clonal complexes--emm75/mefA/ST49, emm12/mefA/ST36 and emm77/ermA/tetO/ST63 comprised over 90% of the tested strains. Although MLVA, PP and VFP distinguished 10, 20 and 12 different patterns, respectively, cluster analysis disclosed only small differences between strains which belonged to the same emm/ST type. Our data indicate dominance of three major internationally widely disseminated macrolide resistant clones and a high genetic homogeneity among the Serbian MRGAS population. Continued surveillance of macrolide resistance and clonal composition in MRGAS in Serbia in future is necessary to determine stability of MRGAS clones and to guide therapy strategies.
authors.affiliation: National Reference Laboratory for Streptococci, Medical Faculty, University of Belgrade, Dr Subotica starijeg 1, 11000 Belgrade, Serbia; Institute of Microbiology and Immunology, Medical Faculty, University of Belgrade, Dr Subotica starijeg 1, 11000 Belgrade, Serbia. Electronic address: natasaopavski@gmail.com.
authors.forename: Natasa
authors.initials: N
authors.lastname: Opavski
authors.affiliation: National Reference Laboratory for Streptococci, Medical Faculty, University of Belgrade, Dr Subotica starijeg 1, 11000 Belgrade, Serbia; Institute of Microbiology and Immunology, Medical Faculty, University of Belgrade, Dr Subotica starijeg 1, 11000 Belgrade, Serbia. Electronic address: ina.gajic@med.bg.ac.rs.
authors.forename: Ina
authors.initials: I
authors.lastname: Gajic
authors.affiliation: Department of Epidemiology and Clinical Microbiology, National Medicines Institute, Chełmska 30/34, 00-750 Warszawa, Poland. Electronic address: aborek@cls.edu.pl.
authors.forename: Anna L
authors.initials: AL
authors.lastname: Borek
authors.affiliation: Department of Epidemiology and Clinical Microbiology, National Medicines Institute, Chełmska 30/34, 00-750 Warszawa, Poland. Electronic address: kobszanska@cls.edu.pl.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Obszańska
authors.affiliation: Institute of Microbiology and Immunology, Medical Faculty, University of Belgrade, Dr Subotica starijeg 1, 11000 Belgrade, Serbia. Electronic address: mstanojevic@med.bg.ac.rs.
authors.forename: Maja
authors.initials: M
authors.lastname: Stanojevic
authors.affiliation: Institute of Microbiology and Immunology, Medical Faculty, University of Belgrade, Dr Subotica starijeg 1, 11000 Belgrade, Serbia. Electronic address: ilazarevic@med.bg.ac.rs.
authors.forename: Ivana
authors.initials: I
authors.lastname: Lazarevic
authors.affiliation: National Reference Laboratory for Streptococci, Medical Faculty, University of Belgrade, Dr Subotica starijeg 1, 11000 Belgrade, Serbia; Institute of Microbiology and Immunology, Medical Faculty, University of Belgrade, Dr Subotica starijeg 1, 11000 Belgrade, Serbia. Electronic address: lazarr@verat.net.
authors.forename: Lazar
authors.initials: L
authors.lastname: Ranin
authors.affiliation: Department of Epidemiology and Clinical Microbiology, National Medicines Institute, Chełmska 30/34, 00-750 Warszawa, Poland. Electronic address: iza.sitkiewicz@gmail.com.
authors.forename: Izabela
authors.initials: I
authors.lastname: Sitkiewicz
authors.affiliation: National Reference Laboratory for Streptococci, Medical Faculty, University of Belgrade, Dr Subotica starijeg 1, 11000 Belgrade, Serbia; Institute of Microbiology and Immunology, Medical Faculty, University of Belgrade, Dr Subotica starijeg 1, 11000 Belgrade, Serbia. Electronic address: veramijac@med.bg.ac.rs.
authors.forename: Vera
authors.initials: V
authors.lastname: Mijac
mesh_terms: D016000:Cluster Analysis; D024881:Drug Resistance, Bacterial; D005798:Genes, Bacterial; D005838:Genotype; D006801:Humans; D018942:Macrolides / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D058885:Multilocus Sequence Typing; D010612:Pharyngitis / Q000382:microbiology*; D010641:Phenotype; D055771:Serbia; D013290:Streptococcal Infections / Q000382:microbiology*; D013297:Streptococcus pyogenes / Q000145:classification / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D014774:Virulence / Q000235:genetics; D037521:Virulence Factors / Q000235:genetics
chemical_list: D018942:Macrolides; D037521:Virulence Factors
keywords: MLST; MLVA; Macrolide resistance; Streptococcus pyogenes; emm