Streptococcus agalactiae is a common agent of clinical and subclinical bovine mastitis and an important cause of human infections, mainly among pregnant women, neonates and nonpregnant adults with underlying diseases. The present study describes the genetic and phenotypic diversity among 392 S. agalactiae human and bovine strains isolated between 1980 and 2006 in Brazil. The most prevalent serotypes were Ia, II, III and V and all the strains were susceptible to penicillin, vancomycin and levofloxacin. Resistance to clindamycin, chloramphenicol, erythromycin, rifampicin and tetracycline was observed. Among the erythromycin resistant strains, mefA/E, ermA and, mainly, ermB gene were detected, and a shift of prevalence from the macrolide resistance phenotype to the macrolide-lincosamide-streptogramin B resistance phenotype over the years was observed. The 23 macrolide-resistant strains showed 19 different pulsed-field gel electrophoresis profiles. Regarding macrolide resistance, a major concern in S. agalactiae epidemiology, the present study describes an increase in erythromycin resistance from the 80s to the 90s followed by a decrease in the 2000-2006 period. Also, the genetic heterogeneity described points out that erythromycin resistance in Brazil is rather due to horizontal gene transmission than to spreading of specific macrolide-resistant clones.

Streptococcus agalactiae isolates are more common among pregnant women, neonates and nonpregnant adults with underlying diseases compared to other demographic groups. In this study, we evaluate the genetic and phenotypic diversity in S. agalactiae strains from Rio de Janeiro (RJ) that were isolated from asymptomatic carriers. We analysed these S. agalactiae strains using pulsed-field gel electrophoresis (PFGE), serotyping and antimicrobial susceptibility testing, as well as by determining the macrolide resistance phenotype, and detecting the presence of the ermA/B, mefA/E and lnuB genes. The serotypes Ia, II, III and V were the most prevalent serotypes observed. The 60 strains analysed were susceptible to penicillin, vancomycin and levofloxacin. Resistance to clindamycin, chloramphenicol, erythromycin, rifampin and tetracycline was observed. Among the erythromycin and/or clindamycin resistant strains, the ermA, ermB and mefA/E genes were detected and the constitutive macrolides, lincosamides and streptogramin B-type resistance was the most prevalent phenotype observed. The lnuB gene was not detected in any of the strains studied. We found 56 PFGE electrophoretic profiles and only 22 of them were allocated in polymorphism patterns. This work presents data on the genetic diversity and prevalent capsular serotypes among RJ isolates. Approximately 85% of these strains came from pregnant women; therefore, these data may be helpful in developing future prophylaxis and treatment strategies for neonatal syndromes in RJ.

Streptococcus agalactiae (GBS) is a major source of human perinatal diseases and bovine mastitis. Erythromycin (Ery) and tetracycline (Tet) are usually employed for preventing human and bovine infections although resistance to such agents has become common among GBS strains. Ery and Tet resistance genes are usually carried by conjugative transposons (CTns) belonging to the Tn916 family, but their presence and transferability among GBS strains have not been totally explored. Here we evaluated the presence of Tet resistance genes (tetM and tetO) and CTns among Ery-resistant (Ery-R) and Ery-susceptible (Ery-S) GBS strains isolated from human and bovine sources; and analyzed the ability for transferring resistance determinants between strains from both origins. Tet resistance and int-Tn genes were more common among Ery-R when compared to Ery-S isolates. Conjugative transfer of all resistance genes detected among the GBS strains included in this study (ermA, ermB, mef, tetM and tetO), in frequencies between 1.10−7 and 9.10−7, was possible from bovine donor strains to human recipient strain, but not the other way around. This is, to our knowledge, the first report of in vitro conjugation of Ery and Tet resistance genes among GBS strains recovered from different hosts.

Staphylococcus aureus ica-independent biofilms are multifactorial in nature, and various bacterial proteins have been associated with biofilm development, including fibronectin-binding proteins A and B, protein A, surface protein SasG, proteases, and some autolysins. The role of extracellular DNA (eDNA) has also been demonstrated in some S. aureus biofilms. Here, we constructed a Tn551 library, and the screening identified two genes that affected biofilm formation, lrgB and yycI. The repressive effect of both genes on the development of biofilm was also confirmed in knockout strains constructed by allelic recombination. In contrast, the superexpression of either lrgB or yycI by a cadmium-inducible promoter led to a decrease in biofilm accumulation. Indeed, a significant increase in the cell-lysis dependent eDNA release was detected when lrgB or yycI were inactivated, explaining the enhanced biofilm formed by these mutants. In fact, lrgB and yycI genes belong to distinct operons that repress bacterial autolysis through very different mechanisms. LrgB is associated with the synthesis of phage holin/anti-holin analogues, while YycI participates in the activation/repression of the two-component system YycGF (WalKR). Our in vivo data suggest that autolysins activation lead to increased bacterial virulence in the foreign body animal model since a higher number of attached cells was recovered from the implanted catheters inoculated with lrgB or yycI knockout mutants.

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Group B streptococci (GBS) infections occur worldwide. Although serotyping has been used for epidemiologic purposes, this does not accurately characterize enough members of a genetically heterogeneous bacterial population. The aims of this work were to evaluate the genetic diversity of 45 type Ia GBS strains isolated in Brazil byGroup B streptococci (GBS) are responsible for a large variety of human infections and have been recognized over the last few decades as a leading cause of perinatal disease worldwide (Farley 2001, Weisner et al. 2004. GBS are classified in serotypes (Ia, Ib and II-VIII) that occur in combination with different protein antigens (alpha, beta and rib) (Dmitriev et al. 2001). Currently, serotypes Ia, III and V are the most common in many countries (Duarte et al. 2005, Fluegge et al. 2005, Bergseng et al. 2008, Poyart et al. 2008, von Both et al. 2008.Pulsed-field gel electrophoresis (PFGE), used to examine GBS strains, is a powerful technique employed for the classification of microorganisms after digestion of the genomic DNA by restriction enzymes (Benson & Ferrieri 2001, Oliveira et al. 2005, von Both et al. 2008. Using polymerase chain reaction (PCR), Franken et al. (2001) suggested that the scpB and lmb genes (encoding c5a peptidase and laminin binding protein) must exist in GBS strains that infect humans. The hylB gene is frequently detected in these strains (Dore et al. 2003). The bac and bca genes are present in 23% and 100% of type Ia strains, respectively (Maeland et al. 1997(Maeland et al. , 2000.The lack of information on Ia Brazilian strains and the availability of DNA techniques led us to investigate the genetic make-up of type Ia GBS strains isolated in distinct regions of Brazil. Additionally, antimicrobial susceptibility was examined to better characterize these isolates. MATERIALS AND METHODSBacterial strains -Forty-five human type Ia GBS strains derived from clinical specimens were obtained in Florianopolis, Santa Catarina (n = 3), a city located in the Southern Region of Brazil, in São Paulo, São Paulo (SP) (n = 1), and in Rio de Janeiro, Rio de Janeiro (n = 40), in the Southeast Region of the country. The source of one strain was unknown.Isolates were obtained from 1981-2002 from public health laboratories, gynaecological clinics, hospitalsand universities. The clinical sources included urine (n = 16), oropharynx (n = 9), vagina (n = 5), anus (n = 2), lung (n = 2), placenta (n = 1), external ear canal (n = 1) and perineum (n = 1). The sources of eight specimens were unknown. A confirmatory identification of serotypes was carried out again by immunoprecipitation in agarose using sera produced in the research facilities of the authors and HCl antigenic extracts from the streptococci (Benchetrit et al. 1982).PFGE -PFGE was performed as previously described (Oliveira et al. 2005). DNA was digested with the SmaI restriction enzyme (Amersham) and submitted to electrophoresis with a program as follows: switch time of 1-30 sec during 23 h, with a 120º angle, at a temperature of ...

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