Conjugative transfer of resistance determinants among human and bovine Streptococcus agalactiae

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.

Distribution of serotypes and evaluation of antimicrobial susceptibility among human and bovine Streptococcus agalactiae strains isolated in Brazil between 1980 and 2006

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 macrolidelincosamide- 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.

Microbiological, technological and therapeutic properties of kefir: a natural probiotic beverage

Kefir is a fermented milk beverage produced by the action of bacteria and yeasts that exist in symbiotic association in kefir grains. The artisanal production of the kefir is based on the tradition of the peoples of Caucasus, which has spread to other parts of the world, from the late 19th century, and nowadays integrates its nutritional and therapeutic indications to the everyday food choices of several populations. The large number of microorganisms present in kefir and their microbial interactions, the possible bioactive compounds resulting of microbial metabolism, and the benefits associated with the use this beverage confers kefir the status of a natural probiotic, designated as the 21th century yoghurt. Several studies have shown that kefir and its constituents have antimicrobial, antitumor, anticarcinogenic and immunomodulatory activity and also improve lactose digestion, among others. This review includes data on the technological aspects, the main beneficial effects on human health of kefir and its microbiological composition. Generally, kefir grains contain a relatively stable and specific microbiota enclosed in a matrix of polysaccharides and proteins. Microbial interactions in kefir are complex due to the composition of kefir grains, which seems to differ among different studies, although some predominant Lactobacillus species are always present. Besides, the specific populations of individual grains seem to contribute to the particular sensory characteristics present in fermented beverages. This review also includes new electron microscopy data on the distribution of microorganisms within different Brazilian kefir grains, which showed a relative change in its distribution according to grain origin.

Bioemulsifier production by Microbacterium sp. strains isolated from mangrove and their application to remove cadmiun and zinc from hazardous industrial residue

The contamination of ecosystems with heavy metals is an important issue in current world and remediation technologies should be in according to environmental sustainability concept. Bioemulsifier are promising agents to be used in metal removal and could be effective to many applications in environmental industries. The aims of this work was screening the potential production of bioemulsifier by microorganisms isolated from an oil contaminated mangrove, and evaluate cadmium and zinc removal potential of those strains from a hazardous industrial residue. From that, bioemulsifier-producing bacteria were isolated from urban mangrove sediments. Four isolates were identified as Microbacterium sp by 16S rRNA analysis and were able to reduce up to 53.3 percent of culture medium surface tension (TS) when using glucose as carbon and energy source and 20.2 percent when sucrose was used. Suspensions containing bioemulsifier produced by Microbacterium sp. strains show to be able to remove cadmium and zinc from contaminated industrial residue, and its ability varied according carbon source. Significant differences in metal removal were observed by all strains depending on the carbon source. When glucose was used, Cd and Zn removal varied from 17 to 41 percent, and 14 to 68 percent, respectively. However, when sucrose was used it was observed only 4 to a maximum of 15 percent of Cd removal, and 4 to 17 percent of Zn removal. When the same tests were performed after ethanol precipitation, the results were different: the percentages of removal of Zn (7-27 percent) and Cd (14-32 percent) were higher from sucrose cultures. This is the first report of heavy metals removal by bioemulsifier from Microbacterium sp.

Use of molecular approach to verify the influence of a eutrophic lagoon in the nearby ocean's bacterioplankton communities

A lagoa Rodrigo de Freitas é um ambiente aquático eutrofizado, cujas águas são lançadas ao mar nas praias de Ipanema e Leblon através do canal do Jardim de Alah. Nesse trabalho, foi estudada a influência desse aporte na comunidade bacteriana dessas praias. Para isso coletou-se água de onze estações distribuídas entre a lagoa e as praias. Essas amostras foram analisadas quanto a parâmetros moleculares e microbiológicos. Foi realizado também PCR-DGGE utilizando-se iniciadores para o gene rpoB, a partir de DNA extraído das amostras de água coletadas. Resultados preliminares mostram que a influência da lagoa na comunidade bacteriana das praias pode ser verificada por todas as abordagens.

Use of molecular approach to verify the influence of a eutrophic lagoon in the nearby ocean's bacterioplankton communities

Rodrigo de Freitas lagoon is an eutrophic aquatic environment. The waters from the lagoon are released to the sea at Ipanema and Leblon beaches, through Jardim de Alah channel. In this work, the influence of these waters on the bacterial communities of these beaches was investigated. Eleven sampling stations were set between the lagoon and the beaches, and the samples were analyzed by molecular and microbiological parameters. PCR-DGGE of the DNA extracted from the samples was performed using rpoB primers. Preliminary results indicate that all used approaches could reveal the influence of the lagoon on the beaches bacterial communities.

A lagoa Rodrigo de Freitas é um ambiente aquático eutrofizado, cujas águas são lançadas ao mar nas praias de Ipanema e Leblon através do canal do Jardim de Alah. Nesse trabalho, foi estudada a influência desse aporte na comunidade bacteriana dessas praias. Para isso coletou-se água de onze estações distribuídas entre a lagoa e as praias. Essas amostras foram analisadas quanto a parâmetros moleculares e microbiológicos. Foi realizado também PCR-DGGE utilizando-se iniciadores para o gene rpoB, a partir de DNA extraído das amostras de água coletadas. Resultados preliminares mostram que a influência da lagoa na comunidade bacteriana das praias pode ser verificada por todas as abordagens.

Molecular microbial ecology: a minireview

Nossos conhecimentos sobre ecologia de microorganismos em ambientes naturais têm sido limitados por se basearem em técnicas clássicas de Microbiologia. Entretanto, os recentes avanços em técnicas de biologia molecular, juntamente com os constantes desenvolvimentos em tecnologias de informaçäo e computadores, têm transformado os estudos de Ecologia Microbiana e abriram uma nova área da Microbiologia denominada Ecologia Molecular Microbiana. Atualmente, estudos sobre comunidades microbianas naturais säo possíveis mesmo sem a necessidade de técnicas baseadas em cultivo, e novas estratégias moleculares têm sido desenvolvidas permitindo a realizaçäo de estudos sobre expressäo gênica, assim como um melhor entendimento sobre as interaçöes entre comunidades microbianas no ecossistema. Algumas das principais e/ou mais recentes técnicas foram revisadas.

Intoxicaçäo por Staphylococcus aureus provocada por carne de peru defumada / Staphylococcus aureus infections caused by smoked meat of turkey

Carne de peru defumada preparada numa confeitaria do bairro de Laranjeiras, RJ, apresentado 4,0 x 10**7 Staphylococcus aureus enterotoxigênico/g, provocou intoxicaçäo em 4 pessoas de mesma família