Antimicrobial susceptibility and genetic relationships among Streptococcus dysgalactiae subsp. equisimilis isolates in Rio de Janeiro.
BACKGROUND
Streptococcus dysgalactiae subsp. equisimilis (SDSE) has been increasingly associated with several infectious diseases, ranging from pharyngitis to life-threatening conditions, such as necrotizing fasciitis and streptococcal toxic shock syndrome. However, its molecular epidemiology in some geographical areas remains unclear.


METHODS
In this study, 44 isolates of SDSE, recovered from noninvasive infections (37) and from carriage (7), during 2008-2013, were submitted to antimicrobial susceptibility testing, emm typing and pulsed-field gel electrophoresis (PFGE) analysis.


RESULTS
All isolates were susceptible to ceftriaxone, levofloxacin, penicillin G and vancomycin. Resistance rates to erythromycin was 18.2% and to clindamycin was 6.8%, while 38.7% of the isolates were tetracycline non-susceptible. Macrolide resistance phenotypes were M (5 isolates), iMLSB (2) and cMLSB (1), associated with mefA/E, ermA and ermB genotypes, respectively. Seventeen emm types with 21 subtypes were found, but 6 types (stG653.0, stC1400.0 with three subtypes, stC839.0, stC36.0 with two subtypes, stG480.0 and stG840.0) were detected in 70.4% of the isolates. Six new emm subtypes were identified (stC1400.12, stC1400.13, emm152.1, emm152.2, stG652.6 and stG6792.5). Twenty-five PFGE profiles were obtained from 39 isolates.


CONCLUSIONS
Congruence between both typing systems was observed, since the majority of isolates belonging to a given emm type clustered together by PFGE. Clones (at least 80% similarity) were also observed among isolates with different emm types, probably due to horizontal recombination of the emm gene. Erythromycin-resistant isolates harbored diverse emm genes and generated different PFGE profiles, showing a polyclonal dissemination of such characteristic among SDSE isolates.
a Departmento de Microbiologia e Parasitologia , Instituto Biomédico, Universidade Federal Fluminense , Niterói , Brazil ;
José Paulo
JP
de Souza
a Departmento de Microbiologia e Parasitologia , Instituto Biomédico, Universidade Federal Fluminense , Niterói , Brazil ;
Amanda Ribeiro
AR
Santos
b Faculdade de Farmácia , Universidade Federal Fluminense , Niterói , Brazil.
Geraldo Renato
GR
de Paula
a Departmento de Microbiologia e Parasitologia , Instituto Biomédico, Universidade Federal Fluminense , Niterói , Brazil ;
Rosana Rocha
RR
Barros
D000293:Adolescent; D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001938:Brazil; D002648:Child; D002675:Child, Preschool; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D006801:Humans; D007223:Infant; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D009960:Oropharynx / Q000382:microbiology; D013290:Streptococcal Infections / Q000382:microbiology*; D013291:Streptococcus / Q000187:drug effects* / Q000235:genetics*; D055815:Young Adult
D000900:Anti-Bacterial Agents
Antimicrobial resistance; PFGE analysis; Streptococcus dysgalactiae subsp. equisimilis; emm typing