RESUMO
Streptococcus agalactiae (GBS) is a colonizing agent in pregnant women, the main cause of invasive neonatal infections, and the reason of serious diseases in non-pregnant adults. Several virulence determinants are involved in the pathogenesis. These include capsular polysaccharide, surface-localized proteins, and toxins. Penicillin is considered the first choice antibiotic for the treatment and prophylaxis; erythromycin, clindamycin and fluoroquinolones are recommended alternatives for penicillin-allergic GBS carriers or patients. Our objective was to investigate the virulence genetic characteristics and the antimicrobial susceptibility of 162 GBS colonizing and infective isolates recovered in Argentina. Serotypes Ia and III were the most prevalent ones, followed by Ib, II, V, IV and non-typeable. In relation to the 13 virulence genes screened, cpsA, cylE, hylB, lmb, and scpB were the most prevalent and could be postulated as vaccine epitopes; bca, rib, bac, hvgA, spb1, PI, PI-2a, and PI-2b were detected in lesser frequencies. No significant association was found between serotypes or virulence genes and colonizing or infective isolates but, on the contrary, significant association was observed between some genes and the most prevalent serotypes, la and III. The cluster analysis showed 52 virulence profiles and, antimicrobial resistance tests, 16 profiles, some with up to 4 resistances. Tetracycline resistance was significantly associated with colonizing isolates. Genes tetM and ermB conferring resistance to tetracyclines and macrolides, respectively, were the most commonly identified. Our findings show that GBS colonizing and infective isolates circulating in Argentina share similar features in terms of serotype and virulence genes and show a high level of antimicrobial resistance.
Assuntos
Infecções Estreptocócicas , Streptococcus agalactiae , Adulto , Recém-Nascido , Humanos , Feminino , Gravidez , Streptococcus agalactiae/genética , Virulência/genética , Antibacterianos/farmacologia , Argentina , Farmacorresistência Bacteriana/genética , Genótipo , Penicilinas , Testes de Sensibilidade MicrobianaRESUMO
Streptococcus dysgalactiae subsp. equisimilis (SDSE) has virulence factors similar to those of Streptococcus pyogenes. Therefore, it causes pharyngitis and severe infections indistinguishable from those caused by the classic pathogen. The objectives of this study were: to know the prevalence of SDSE invasive infections in Argentina, to study the genetic diversity, to determine the presence of virulence genes, to study antibiotic susceptibility and to detect antibiotic resistance genes. Conventional methods of identification were used. Antibiotic susceptibility was determined by the disk diffusion and the agar dilution methods and the E-test. Twenty eight centers from 16 Argentinean cities participated in the study. Twenty three isolates (16 group G and 7 group C) were obtained between July 1 2011 and June 30 2012. Two adult patients died (8.7%). Most of the isolates were recovered from blood (60.9%). All isolates carried speJ and ssa genes. stG62647, stG653 and stG840 were the most frequent emm types. Nineteen different PFGE patterns were detected. All isolates were susceptible to penicillin and levofloxacin, 6 (26.1%) showed resistance or reduced susceptibility to erythromycin --#91;1 mef(A), 3 erm(TR), 1 mef(A) + erm(TR) and 1 erm(TR) + erm(B)--#93; and 7 (30.4%) were resistant or exhibited reduced susceptibility to tetracycline --#91;2 tet(M), 5 tet(M) + tet(O)--#93;. The prevalence in Argentina was of at least 23 invasive infections by SDSE. A wide genetic diversity was observed. All isolates carried speJ and ssa genes. Similarly to other studies, macrolide resistance (26.1%) was mainly associated to the MLS B phenotype.
Streptococcus dysgalactiae subsp. equisimilis (SDSE) posee factores de virulencia similares a Streptococcus pyogenes y, en consecuencia, produce faringitis e infecciones graves indistinguibles de las generadas por este patógeno clásico. Los objetivos del estudio fueron conocer la prevalencia de SDSE en infecciones invasivas en Argentina, estudiar su diversidad genética, determinar la presencia de genes de virulencia, ensayar su sensibilidad a los antibióticos y conocer los genes de resistencia. Se emplearon métodos convencionales de identificación. La sensibilidad se determinó por difusión, Etest y dilución en agar. Participaron 28 centros de 16 ciudades argentinas. Se obtuvieron 23 aislamientos (16 del grupo G y 7 del grupo C) desde el 1-7-2011 hasta el 30-6-2012. Se registraron 2 muertes en adultos (8,7%). La mayoría de los aislamientos fueron obtenidos de sangre (60,9%). Todos eran portadores de los genes speJ y ssa. Los genotipos más frecuentes fueron stG62647, stG653 y stG840. Se detectaron 19 pulsotipos distintos. Todos los aislamientos fueron sensibles a penicilina y levofloxacina, 6 (26,1%) presentaron resistencia o sensibilidad disminuida a eritromicina (1 mef--#91;A--#93;, 3 erm--#91;TR--#93;, 1 mef--#91;A--#93; + erm--#91;TR--#93; y 1 erm--#91;TR--#93; + erm--#91;B--#93;) y 7 (30,4%) fueron resistentes o tuvieron sensibilidad disminuida a tetraciclina (2 tet--#91;M--#93;, 5 tet--#91;M--#93; + tet--#91;O--#93;). La prevalencia anual en la Argentina fue de al menos 23 infecciones invasivas por SDSE y se observó una amplia diversidad genética. Todos los aislamientos presentaron los genes ssa y speJ. Como en otros estudios, la resistencia a macrólidos (26,1%) estuvo asociada, principalmente, al fenotipo MLS B.
Assuntos
Humanos , Masculino , Feminino , Infecções Estreptocócicas/classificação , Streptococcus/isolamento & purificação , Streptococcus/patogenicidade , Argentina , Streptococcus/genética , Resistência Microbiana a Medicamentos , Estudos Transversais/métodosRESUMO
Streptococcus dysgalactiae subsp. equisimilis (SDSE) has virulence factors similar to those of Streptococcus pyogenes. Therefore, it causes pharyngitis and severe infections indistinguishable from those caused by the classic pathogen. The objectives of this study were: to know the prevalence of SDSE invasive infections in Argentina, to study the genetic diversity, to determine the presence of virulence genes, to study antibiotic susceptibility and to detect antibiotic resistance genes. Conventional methods of identification were used. Antibiotic susceptibility was determined by the disk diffusion and the agar dilution methods and the E-test. Twenty eight centers from 16 Argentinean cities participated in the study. Twenty three isolates (16 group G and 7 group C) were obtained between July 1 2011 and June 30 2012. Two adult patients died (8.7%). Most of the isolates were recovered from blood (60.9%). All isolates carried speJ and ssa genes. stG62647, stG653 and stG840 were the most frequent emm types. Nineteen different PFGE patterns were detected. All isolates were susceptible to penicillin and levofloxacin, 6 (26.1%) showed resistance or reduced susceptibility to erythromycin [1 mef(A), 3 erm(TR), 1 mef(A)+erm(TR) and 1 erm(TR)+erm(B)] and 7 (30.4%) were resistant or exhibited reduced susceptibility to tetracycline [2 tet(M), 5 tet(M)+tet(O)]. The prevalence in Argentina was of at least 23 invasive infections by SDSE. A wide genetic diversity was observed. All isolates carried speJ and ssa genes. Similarly to other studies, macrolide resistance (26.1%) was mainly associated to the MLSB phenotype.
