Phenotypic and Genotypic Characterization of Group B Streptococcal Isolates in Southern Brazil

Abstract

One-hundred sixty-eight group B streptococcal (GBS) isolates from a Brazilian hospital were phenotypically and genotypically characterized. Isolates were recovered from human sources from April 2006 to May 2008 and classified as either invasive, noninvasive, or colonizing isolates. Classical methods for serotyping and antibiotic resistance profiling were employed. Clonal groups were also defined by pulsed-field gel electrophoresis (PFGE). Results showed that susceptibility to beta-lactam antimicrobials was predominant among the isolates. Only 4.7% were resistant to erythromycin and clindamycin. The erm(B) gene was widely detected in our GBS isolates, according to our phenotypic results (constitutive macrolide-lincosamide-streptogramin B [cMLS B ] resistance phenotype), and the erm(A) gene was also detected in some isolates. MLS B resistance was restricted to strains isolated from patients with noninvasive infections and carriers. Serotype Ia was predominant (38.1%), serotype IV isolates were found at a high frequency (13.1%), and few isolates of serotype III were identified (3%). Pulsed-field gel electrophoresis results revealed a variety of types, reflecting the substantial genetic diversity among GBS strains, although a great number of isolates could be clustered into two major groups with a high degree of genetic relatedness. Three main PFGE clonal groups were found, and isolates sharing the same PFGE type were grouped into different serotypes. Furthermore, in a few cases, isolates from the same patients and possessing the same PFGE type were of different serotypes. These findings could be related to the occurrence of capsular switching by horizontal transfer of capsular genes.In the last 40 years, Streptococcus agalactiae (group B streptococcus [GBS]) has been described as an important pathogen in neonates and pregnant women. Vaginal colonization with GBS during pregnancy is significantly associated with infections in newborns and requires investigation (40,46,48). Despite the reduction in the incidence of early-onset neonatal disease by using antimicrobial intrapartum prophylaxis, mortality and permanent disability rates caused by GBS continue to be significant. However, GBS has also emerged as an important pathogen in other patient groups, such as children, young adults with underlying medical conditions, and elderly individuals (40). Penicillin is the drug of choice for prevention and treatment of GBS infections, which remain universally susceptible. Erythromycin and clindamycin are recommended when risks of anaphylaxis or therapeutic failure are present. However, resistance to erythromycin and clindamycin has increased in many countries in North America (2,6,16,40), Europe (21,22,42,45), and Asia (24) but not in Brazil (18,50) and other Latin American countries (23,35,36). Such a resistance profile is mainly due to two mechanisms: a methylasemediated target site modification and an active efflux pump (53). In GBS, coresistance to macrolide, lincosamide, and streptogramin B (MLS B ) is due to methylases e...

Epidemiological surveillance of colonising group B Streptococcus epidemiology in the Lisbon and Tagus Valley regions, Portugal (2005 to 2012): emergence of a new epidemic type IV/clonal complex 17 clone

“…The same scenario was observed among neonatal (2/64 cases; 3%) for the years 2000 to 2004 [12] and non-pregnant adult infections (2/225 cases; 1%) from 2001 to 2008 [14]. After 2010, reports from Brazil Ireland and the US [15][16][17][18] revealed an increased prevalence of serotype IV in colonisation and infection, suggesting the possibility that this serotype could be emerging as an important pathogen, as happened with serotype V during the 1990s [19].…”

“…The sudden increase of GBS serotype IV detection in different countries does not rely on the emergence of type IV/CC17 only, as other genetic lineages (such as CC1 and CC23) or different types of pulsed-field gel electrophoresis have been identified, constituting the majority of the serotype IV isolates [15][16][17][18]20]. A careful surveillance of GBS type IV/ST291 emergence is recommended, in order to define its host specificity, tropism, virulence potential and antibiotic resistance phenotype.…”

Taxa de infecção e sorotipos de Streptococcus agalactiae em amostras de recém-nascidos infectados na cidade de Campinas (SP), Brasil

“…40,41 . Mais recentemente, em 2010, um estudo de Curitiba (PR) revelou os tipos Ia e Ib como os mais frequentes em doença de início precoce, e o IV na infecção tardia, com apenas sete casos descritos 42 . O que chama a atenção é que os sorotipos Ib e II, que predominaram na maioria dos estudos brasileiros, não são considerados de maior virulência.…”

Emergence of Serotype IV Group B Streptococcus Adult Invasive Disease in Manitoba and Saskatchewan, Canada, Is Driven by Clonal Sequence Type 459 Strains

“…To our knowledge, this proportion is the highest ever reported for serotype IV GBS adult invasive disease. While we did not characterize the GBS serotype distribution among colonized pregnant women (these studies are under way in our laboratories), others have observed increasing numbers of serotype IV strains among colonizing isolates (17,18,(38)(39)(40). Studies aimed at developing a capsular polysaccharide antigen-based GBS vaccine are ongoing worldwide, with several formulations that do not include serotype IV already under clinical trials (41).…”