Comparative analysis of agr groups and virulence genes among subclinical and clinical mastitis Staphylococcus aureus isolates from sheep flocks of the Northeast of Brazil

Staphylococcus aureus is one of the most frequent mastitis causative agents in small ruminants. The expression of most virulence genes of S. aureus is controlled by an accessory gene regulator (agr)locus. This study aimed to ascertain the prevalence of the different agr groups and to evaluate the occurrence of encoding genes for cytotoxin, adhesins and toxins with superantigen activity in S. aureus isolates from milk of ewes with clinical and subclinical mastitis in sheep flocks raised for meat production The agr groups I and II were identified in both cases of clinical and subclinical mastitis. Neither the arg groups III and IV nor negative agr were found. The presence of cflA gene was identified in 100% of the isolates. The frequency of hla and lukE-D genes was high -77.3 and 82.8%, respectively and all isolates from clinical mastitis presented these genes. The sec gene, either associated to tst gene or not, was identified only in isolates from subclinical mastitis. None of the following genes were identified: bbp, ebpS, cna, fnbB, icaA, icaD, bap, hlg, lukM-lukF-PV and se-a-b-d-e.

Pseudomonas aeruginosa multirresistente: um problema endêmico no Brasil / Multidrug-resistant Pseudomonas aeruginosa: an endemic problem in Brazil

Relatos mundiais têm documentado a problemática da endemicidade de isolados clínicos de Pseudomonas aeruginosa multirresistente (MDR) aliada a elevados índices de morbidade/mortalidade. No Brasil, surtos de infecção ocasionados por P. aeruginosa têm sido relacionados com uma disseminação clonal da espécie. Atualmente, as opções terapêuticas para o tratamento das infecções causadas por esse microrganismo são limitadas, muitas vezes restringindo-se ao uso de carbapenêmicos (p. ex., imipenem [IPM]). Assim, a resistência ao IPM é uma questão de saúde pública, uma vez que esse antibiótico é empregado como último recurso no tratamento de infecções de origem hospitalar, causadas por bactérias Gram-negativas multirresistentes. No Brasil, os principais mecanismos relacionados com fenótipos multirresistentes de P. aeruginosa são produção de metalobetalactamase (MBL) do tipo SPM-1, presença de metilase 16S rRNA RmtD, perda de porina OprD e superexpressão de bombas de efluxo, o que pode explicar os altos índices de resistência a carbapenêmicos e aminoglicosídeos. A emergência de cepas com essas características é preocupante, tendo em vista a escassez de terapias efetivas no tratamento de infecções por esse patógeno. Finalmente, com base em relatos nacionais, publicados por diferentes grupos de pesquisa, podemos deduzir que a convergência de múltiplos mecanismos de resistência em P. aeruginosa tem sido um evento favorável para a seleção de diferentes clones endêmicos multirresistentes disseminados no Brasil.

Global reports have documented the endemicity of multidrug-resistant (MDR) Pseudomonas aeruginosa associated with high levels of morbidity/mortality. In Brazil, outbreaks of MDR P. aeruginosa have been related to clonal dissemination. Currently, therapeutic options for the treatment of these infections are restricted to carbapenemic antibiotics (i.e., imipenem [IPM]). Thus, carbapenem resistance is a public health issue, since carbapenems are considered the last resort to nosocomial infections caused by MDR Gram-negative bacteria. In Brazil, the main mechanisms associated with MDR P. aeruginosa phenotypes are metallo-betalactamase (MBL) production (SPM-1 enzyme), presence of 16S rRNA methylase RmtD, loss of OprD porin, and overexpression of efflux pumps, which may explain the high level of carbapenem and aminoglycoside resistance. Accordingly, the emergence and dissemination of MDR strains is worrisome. Finally, based on national reports published by different groups of investigators, it is deduced that the convergence of multiple mechanisms of P. aeruginosa resistance has played a major role in the selection of endemic MDR clones widespread in Brazil.

Methicillin-resistant Staphylococcus aureus (MRSA) carriage in a dermatology unit

OBJECTIVE: The aim of this study was to characterize Staphylococcus aureus (MRSA) carriage in a dermatology unit. METHODS: This was a prospective and descriptive study. Over the course of 26 weeks, surveillance cultures were collected weekly from the anterior nares and skin of all patients hospitalized in a 20-bed dermatology unit of a tertiary-care hospital. Samples from healthcare workers (HCWS) were cultured at the beginning and end of the study. Colonized patients were put under contact precautions, and basic infection control measures were enforced. Staphylococcus aureus colonization pressure was determined monthly. Colonized and non-colonized patients were compared, and isolates were evaluated for antimicrobial susceptibility, SCCmec type, virulence factors, and type. RESULTS: Of the 142 patients evaluated, 64 (45 percent) were colonized by MRSA (39 percent hospital acquired; 25 percent community acquired; 36 percent indeterminate). Despite isolation precautions, hospital-acquired Staphylococcus aureus occurred in addition to the continuous entry of Staphylococcus aureus from the community. Colonization pressure increased from 13 percent to 59 percent, and pemphigus and other bullous diseases were associated with MRSA colonization. Eleven out of 71 HCWs (15 percent) were Staphylococcus aureus carriers, although only one worker carried a persistent clone. Of the hospital-acquired MRSA cases, 14/28 (50 percent) were SCCmec type IV (3 PFGE types), 13 were SCCmec type III (46 percent), and one had an indeterminate type. These types were also present among the community-acquired Staphylococcus aureus isolates. SSCmec type IV isolates were shown to be more susceptible than type III isolates. There were two cases of bloodstream infection, and the pvl and tst virulence genes were absent from all isolates. CONCLUSIONS: Dermatology patients were colonized by community- and hospital-acquired Staphylococcus aureus. Half of the nosocomial Staphylococcus aureus isolates were SCCmec type IV. Despite the identification of colonized patients and the subsequent contact precautions and room placement, Staphylococcus aureus colonization continued to occur, and colonization pressure increased. Pemphigus and other bullous diseases were associated with Staphylococcus aureus.

Extended-spectrum beta-lactamases among Enterobacteriaceae isolated in a public hospital in Brazil / Beta-lactamases de espectro estendido em Enterobacteriaceae isoladas de Hospital Público no Brasil

Extended-spectrum β-lactamases (ESBL) in enterobacteria are recognized worldwide as a great hospital problem. In this study, 127 ESBL-producing Enterobacteriaceae isolated in one year from inpatients and outpatients at a public teaching hospital at São Paulo, Brazil, were submitted to analysis by PCR with specific primers for blaSHV, blaTEM and blaCTX-M genes. From the 127 isolates, 96 (75.6 percent) Klebsiella pneumoniae, 12 (9.3 percent) Escherichia coli, 8 (6.2 percent) Morganella morganii, 3 (2.3 percent) Proteus mirabilis, 2 (1.6 percent) Klebsiella oxytoca, 2 (1.6 percent) Providencia rettgeri, 2 (1.6 percent) Providencia stuartti, 1 (0.8 percent) Enterobacter aerogenes and 1 (0.8 percent) Enterobacter cloacae were identified as ESBL producers. BlaSHV, blaTEM and blaCTX-M were detected in 63 percent, 17.3 percent and 33.9 percent strains, respectively. Pulsed field gel eletrophoresis genotyping of K. pneumoniae revealed four main molecular patterns and 29 unrelated profiles. PCR results showed a high variety of ESBL groups among strains, in nine different species. The results suggest the spread of resistance genes among genetically different strains of ESBL-producing K. pneumoniae in some hospital wards, and also that some strongly related strains were identified in different hospital wards, suggesting clonal spread in the institutional environment.

Beta-lactamases de espectro estendido (ESBL) em enterobactérias são reconhecidas mundialmente como um grande problema hospitalar. Neste estudo, 127 Enterobacteriaceae produtoras de ESBL isoladas por um ano, de pacientes internados e ambulatoriais de um hospital público de ensino em São Paulo, Brasil, foram submetidas à análise pela PCR com iniciadores específicos para os genes blaSHV, blaTEM e blaCTX-M. Dos 127 isolados, 96 (75,6 por cento) K. pneumoniae, 12 (9,3 por cento) E. coli, 8 (6,2 por cento) M. morganii, 3 (2,3 por cento) Proteus mirabilis, 2 (1,6 por cento) Klebsiella oxytoca, 2 (1,6 por cento) Providencia rettgeri, 2 (1,6 por cento) Providencia stuartti, 1 (0,8 por cento) Enterobacter aerogenes e 1 (0,8 por cento) Enterobacter cloacae foram identificados como produtores de ESBL. BlaSHV, blaTEM e blaCTX-M foram detectados em 63 por cento, 17,3 por cento e 33,9 por cento das cepas, respectivamente. A genotipagem de K. pneumoniae por eletroforese em campo pulsado revelou quatro padrões moleculares principais e 29 perfis não relacionados. Os resultados da PCR demonstraram alta variedade de grupos de ESBL entre as cepas, em nove espécies diferentes. Os resultados sugerem a disseminação de genes de resistência entre cepas geneticamente diferentes de K. pneumoniae produtoras de ESBL em algumas unidades do hospital, e também que algumas cepas fortemente relacionadas foram identificadas em unidades hospitalares diferentes, sugerindo disseminação clonal no ambiente da instituição.

Avaliação da tolerância à vancomicina em 395 cepas hospitalares de Staphylococcus aureus resistentes à oxacilina / Evaluation of the tolerance to vancomycin in 395 oxacillin-resistant Staphylococcus aureus strains isolated from Brazilian hospitals

O objetivo deste estudo foi avaliar a presença de tolerância à vancomicina em cepas de Staphylococus aureus resistentes à oxacilina (ORSA) isoladas de quatro hospitais da cidade de São Paulo. Foram estudadas 395 cepas ORSA isoladas de pacientes hospitalizados entre outubro de 1998 e maio de 2000. A determinação da concentração inibitória mínima (CIM) e da concentração bactericida mínima (CBM) para vancomicina foi realizada conforme padronizado pelo National Committee for Clinical Laboratory Standards (NCCLS). A tolerância à vancomicina foi definida como a razão CBM/CIM maior ou igual 32. Do total de cepas estudadas, 10,4 por cento apresentaram CIM de 0,5µg/ml para vancomicina; 41,3 por cento, CIM de 1µg/ml; 42,2 por cento, CIM de 2µg/ml; e 6,1 por cento, CIM de 4µg/ml. Em média, 49,1 por cento dos Orsa apresentaram tolerância à vancomicina entre as cepas Orsa foi considerada elevada. Conseqüentemente, aumentam as chances de falhas no tratamento com vancomicina, além de aumentar o risco da emergência de Staphylococcus aureus vancomicina-intermediário

Characterization of the Brazilian endemic clone of methicillin-resistant staphylococcus aureus (MRSA) from hospitals throughout Brazil

The objective of this study was to characterize patterns of the Brazilian endemic clone of methicillin-resistant staphylococcus aureus (MRSA) from hospitals throughout Brazil. We studied 83 MRSA strains isolated from patients hospitalized in 27 public and private hospitals in 19 cities located in 14 brazilian states from september, 1995, to june, 1997. The MRSA strains were typed using antibiograms, bacteriophage typing and pulsed field gel electrophoresis (PFGE). The analysis of genomic DNA by PFGE showed that 65 isolates presented the same SFGE pattern. This pattern was presente in all of the hospitals studied indicating the presence of an endemic MRSA clone widely disseminated throughout brazilian hospitals (BEC). All isolates belonging to the BEC proved to be resistant to ciprofloxacin, erythromycin, lincomycin, trimethoprim-sulphamethoxazole, and tetracycline. Variable susceptibility to these drugs was found only in isolates belonging to clones other than the BEC. The results show that, among MRSA, the BEC is common in Brazil. The best method for mapping changes in the frequency of this clone among MRSA is pulsed field gel electrophoresis. Use of molecular mapping is an important tool for monitoring the spread of potentially dangerous microbes.

Estudo do perfil de resistência de 626 cepas de Staphylococcus aureus isolados de 25 hospitais brasileiros entre setembro de 1995 e junho de 1997 / Study of the resistance profile of 626 strains of staphylococcus aureus isolated in 25 Brazilian Hospitals from September/95 do June/97

O objetivo deste estudo foi avaliar o perfil de resistência de cepas de Staphylococcus aureus isoladas de várias regiöes do Brasil. Foram estudadas 626 cepas provenientes de 25 hospitais, como mais de 250 leitos, localizados em 14 estados. O antibiograma foi realizado do método de difusäo de discos (kirby-Bauer), utilizando 12 antibióticos. As cepas oxacilino-resistentes (Orsa) foram também testadas empregando a técnica de microdiluiçäo em caldo por meio do Sistema MicroScan-Baxter Inc. Das 626 cepas enviadas, 388 foram oxacilino-sensíveis (Ossa) e 238 Orsa. Dentre as cepas Ossa, os percentuais de resistência encontrados foram: penicilina (87,1 por cento), eritromicina (16,2), tetraciclina (15,7), lincomicina (7,5), cloranfenicol (3,1), rifampicina (1,6), sulfametoxazol (SUT) (0,8 por cento), netilmicina (0,5) e ciprofloxacina (0,03). Dentre as cepas Orsa, 99,6 foram resistentes à eritromicina, lincomicina e tetraciclina, 96,2 ao SUT, 2 por cento à ciprofloxacina, 73,1 ao cloranfenicol, 71 à netilmicina e 22,7 à rifampicina. Todas as amostras foram sensíveis à vancomicina. As cepas de S. aureus isoladas no Brasil apresentam níveis mais elevados de resistência que os relatos em outros países. Ciprofloxacina, eritromicina, tetraciclina, lincomicina e SUT foram os antibióticos que apresentaram os mais elevados níveis de resistência. As elevadas taxas de resistência poderiam ser conseqüencia do uso em larga escala de antibióticos, que teria contribuído para a seleçäo de clones mutirresistentes