Bacterial biofilms with emphasis on coagulase-negative staphylococci

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Identification and antimicrobial susceptibility of Staphylococcus from home-treated peritoneal dialysis patients

Staphylococcus aureus is the main agent of infections during peritoneal dialysis (PD). The presence of S. aureus in the nasal cavity has been extensively studied and suggested as a risk factor of dialysis-related infections, whereas coagulase-negative Staphylococcus (CNS) species are frequently considered part of the normal human microbiota. The aim of this study was to identify Staphylococcus in the nasal cavity, pericatheter skin and peritoneal effluent from PD patients, as well as to evaluate the antimicrobial activity evolution in vitro. Thirty-two chronic PD patients were observed during 12 months and had nasal and pericatheter skin samples collected for culture. When peritonitis was detected, samples were also collected from the peritoneal effluent for culture. The activity of several antimicrobial drugs (penicillin G, oxacillin, cephalothin, ofloxacin, netilmicin and vancomycin) against different Staphylococcus species was measured by using the agar drug diffusion assay (Kirby-Bauer method). Staphylococcus was separated into S. aureus, S. epidermidis and other CNS species in order to determine the in vitro resistance level. S. epidermidis resistance to oxacillin progressively increased during the study period (p < 0.05). Resistance to ofloxacin was inexpressive, whereas resistance to netilmicin and vancomycin was not detected. of the oxacillin-resistant species (n = 74), 83% were S. epidermidis, 13% other CNS and 4% S. aureus (p < 0.05). Regarding multidrug resistant strains (n = 45), 82% were S. epidermidis, 13% other CNS, and 5% S. aureus (p < 0.05). This study shows the relevance of resistance to oxacillin and CNS multi-drug resistance, particularly concerning S. epidermidis, in PD patients.

Phenotype characterization of Staphylococcus species strains isolated from buffalo (Bubalus bubalis) milk

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Antimicrobial susceptibility of coagulase-negative Staphylococci isolated from mastitic cattle in Brazil

Um total de 109 cepas de Staphylococci coagulase-negativa foi isolado de leite de vacas com mastite clínica e subclínica, em 35 fazendas, situadas em nove estados brasileiros, no período de fevereiro a maio de 2005. Os isolados foram investigados em relação a susceptibilidade in vitro a diversos agentes antimicrobianos. A resistência à penicilina foi a observação mais freqüente (93,5%), seguida por sulfonamida (88,9%), novobiocina (88,6%) e ampicilina (85,3%). Todas as cepas examinadas mostraram resistência a pelo menos uma das drogas antimicrobianas testadas. Cepas apresentando resistência múltipla foram extremamente comuns, com 10,0% dos microrganismos isolados apresentando resistência a todas as drogas antimicrobianas. Os resultados obtidos indicaram que as cepas de Staphylococci coagulase-negativas, isoladas no Brasil, apresentaram um alto grau de resistência a antimicrobianos. Estes resultados são, provavelmente, uma conseqüência da pressão devida ao uso intensivo de drogas antimicrobianas.

Ocorrência de mastite bovina causada por Staphylococcus sp., Streptococcus sp. E Candida sp. em uma propriedade rural no município de Indianópolis – Minas Gerais

The objective of this study was to evaluate the occurrence of bovine mastitis by Staphylococcus sp., Streptococcus sp. and Candida sp. in a rural area of Indianopolis, Minas Gerais. It was realized the California Mastitis Test (CMT) in six collect, a total 671 of milk sample positive. Then the microbiological examination was performed, where the results revealed the presence of 137 milk samples with microbial multiplication. These, showed the presence of Staphylococcus aureus (45.2% of strains), other coagulase negative Staphylococcus (10.2%), Staphylococcus epidermidis (9.4%), Staphylococcus simulans (5.8%), other coagulase negative (15.3%), Streptococcus agalactiae (7.2%), other Streptococcus sp. (5.1%) and yeasts (1.4%). It was found that 100% of Staphylococcus were susceptible to rifampicin, gentamicin and ciprofloxacin; but, resistant to penicillin, tetracycline, and oxacillin. Regarding antimicrobial susceptibility Streptococcus, were employed, except to clindamycin, erythromycin and tetracycline. We conclude that there is a great necessity of proper hygiene practices and taking prophylactic measures taken in order to reduce the infection of animals caused by infectious microorganisms and resistance.

Detecção da produção de slime por estafilococos coagulase-negativa isolados de cateter venoso central

Slime production is an important virulence factor of coagulase-negative Staphylococcus spp., allowing them to attach to smooth surfaces of biomaterials, and it has been associated with infections of implanted medical devices. In the present study the production of slime capsules in 27 strains of coagulase-negative Staphylococcus was investigated by culture in Congo Red agar (77.7% positivity), spectrophotometric or microplate method (81.4% positivity) and scanning electron microscopy (88.9% positivity). The resistance of coagulase-negative strains of Staphylococcus to various antimicrobial agents was also determined by agar disk diffusion. The proportion of strains resistant to penicillin G, oxacillin, erythromycin, clindamycin and gentamicin among the slime-producing staphylococci was 88.9%, 70.4%, 81.5%, 66.7% and 59.2%, respectively; all of the coagulase-negative staphylococci were susceptible to vancomycin. The strains isolated from central venous catheters were identified by a conventional method and the API Staph system. The 27 coagulase-negative Staphylococcus strains were identified as: S. saprophyticus (3.7%), S. xylosus (7.4%), S. haemolyticus (14.8%), S. epidermidis (37.0%), S. warneri (14.8%), S. lugdunensis (7.4%), S. hominis (7.4%), S. schleiferi (3.7%) and S. chromogenes (3.7%). It can be concluded that in the most of the coagulase-negative Staphylococcus species there was an association between slime production, the nosocomial origin of the strains and reduced sensitivity to the antibiotics, suggesting a pathogenic potential in the hospital environment.

Comparison of methods for the detection of biofilm production in coagulase-negative staphylococci

Background: The ability of biofilm formation seems to play an essential role in the virulence of coagulase-negative staphylococci (CNS). The most clearly characterized component of staphylococcal biofilms is the polysaccharide intercellular adhesin (PIA) encoded by the icaADBC operon. Biofilm production was studied in 80 coagulase-negative staphylococci (CNS) strains isolated from clinical specimens of newborns with infection hospitalized at the Neonatal Unit of the University Hospital, Faculty of Medicine of Botucatu, and in 20 isolates obtained from the nares of healthy individuals without signs of infection. The objective was to compare three phenotypic methods with the detection of the icaA, icaD and icaC genes by PCR. Findings: Among the 100 CNS isolates studied, 82% tested positive by PCR, 82% by the tube test, 81% by the TCP assay, and 73% by the CRA method. Using PCR as a reference, the tube test showed the best correlation with detection of the ica genes, presenting high sensitivity and specificity. Conclusions: The tube adherence test can be indicated for the routine detection of biofilm production in CNS because of its easy application and low cost and because it guarantees reliable results with excellent sensitivity and specificity. © 2010 Cunha et al; licensee BioMed Central Ltd.

Caracterização da resistência à oxacilina em Staphylococcus aureus isolados de feridas de pacientes atendidos em Unidades Básicas de Saúde da cidade de Botucatu

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Determinação da virulência e da resistência antimicrobiana em Staphylococcus spp. isolados de pacientes do Serviço de Dermatologia do Hospital das Clínicas da Faculdade de Medicina de Botucatu, SP

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Epidemiologia molecular aplicada ao estudo da mastite caprina causada por Staphylococcus spp

Pós-graduação em Medicina Veterinária - FCAV

Similaridade genética pelo RAPD-PCR de cepas de Staphylococcus sp isolados de portadores humanos e de camas de uma unidade hospitalar

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Staphylococcus rostri sp. nov., a haemolytic bacterium isolated from the noses of healthy pigs

Twenty coagulase-negative Staphylococcus strains displaying alpha-haemolysis (delta-haemolysin) on sheep-blood agar were isolated from the noses of different pigs in Switzerland. The strains were Gram-stain-positive, non-motile cocci, catalase-positive and coagulase-negative. Sequence analysis of the 16S rRNA gene, sodA, rpoB, dnaJ and hsp60 and phylogenetic characteristics revealed that the strains showed the closest relatedness to Staphylococcus microti CCM 4903(T) and Staphylococcus muscae DSM 7068(T). The strains can be differentiated from S. microti by the absence of mannose fermentation and arginine arylamidase and from S. muscae by the absence of beta-glucuronidase activity and production of alkaline phosphatase. The chosen type strain ARI 262(T) shared 20.1 and 31.9 % DNA relatedness with S. microti DSM 22147(T) and S. muscae CCM 4903(T), respectively, by DNA-DNA hybridization. iso-C(15 : 0), anteiso-C(15 : 0) and iso-C(17 : 0) were the most common fatty acids. Cell-wall structure analysis revealed the peptidoglycan type A3alpha l-Lys-Gly(2)-l-Ser-Gly (type A11.3). The presence of teichoic acid was determined by sequencing the N-acetyl-beta-d-mannosaminyltransferase gene tarA, which is involved in biosynthesis of ribitol teichoic acid. Menaquinone 7 (MK-7) was the predominant respiratory quinone. The G+C content of ARI 262(T) was 38.8 mol%. The isolated strains represent a novel species of the genus Staphylococcus, for which we propose the name Staphylococcus rostri sp. nov. The type strain is ARI 262(T) (=DSM 21968(T) =CCUG 57266(T)) and strain ARI 602 (=DSM 21969 =CCUG 57267) is a reference strain.

Antibiotic resistance profile of Staphylococcus rostri, a new species isolated from healthy pigs

Staphylococcus rostri is a newly described Staphylococcus species that is present in the nasal cavity of healthy pigs. Out of the 225 pigs tested at slaughterhouse, 46.7% carried the new species alone and 22% in combination with Staphylococcus aureus. An antibiotic resistance profile was determined for S. rostri and compared to that of S. aureus isolated from the same pig. Resistance to tetracycline specified by tet(M), tet(K) and tet(L), streptomycin (str(pS194)), penicillin (blaZ), trimethoprim (dfr(G)), and erythromycin and clindamycin (erm genes), were found in both species; however, with the exception of streptomycin and trimethoprim, resistance was higher in S. aureus. S. rostri isolates display very low genetic diversity as demonstrated by pulsed-field gel electrophoresis, which generated two major clusters. Several clonal complexes (CC1, CC5, CC9, CC30 and CC398) were identified in S. aureus with CC 9 and CC 398 being the most frequent. Our study gives the first overview of the distribution, genetic relatedness, and resistance profile of one coagulase-negative Staphylococcus species that is commonly present in the nares of healthy pigs in Switzerland, and shows that S. rostri may harbor resistance genes associated with transferable elements like Tn916.

BIOCHEMICAL CHARACTERIZATION AND CLINICAL SIGNIFICANCE OF COAGULASE-NEGATIVE STAPHYLOCOCCI

Although coagulase-negative staphylococci (C-NS) have been implicated in certain human infections, they are generally regarded as contaminants and their clinical significance is questioned. To assess their role as pathogens, 205 isolates of C-NS from wounds, and body fluids (blood, urine, pleural and peritoneal fluids, etc.) were studied. Patient's charts were reviewed and using strict criteria a determination was made regarding the clinical significance of these isolates. The organisms were then identified using the scheme of Kloos and Schleifer to determine if certain species of C-NS were associated with specific infections. S. epidermidis sensu stricto accounted for 81% of the C-NS isolated; the frequency of other species was S. haemolyticus (6%), S. hominis (5%), S. capitis (4%), S. warneri (3%), and others (1%). Only two isolates were novobiocin resistant; neither was identified as S. saprophyticus. Using these criteria, 22% of C-NS were considered to be clinically significant and the majority of these (93%) were due to S. epidermidis. The most common source of the clinically relevant C-NS isolates was from wounds. These data suggest that identifying C-NS species other than S. epidermidis may be of limited value in predicting clinical significance.^ In addition, selected pathogenic and non-pathogenic strains of C-NS were compared for their ability to adhere to human cells in vitro. Although the results were not conclusive, it appeared that pathogenic C-NS adhered more avidly than non-pathogenic C-NS to buccal cells. Experiments with HeLa cells showed no difference between pathogenic and non-pathogenic C-NS in adherence abilities. ^

Evaluation of routine microbiological techniques for establishing the diagnosis of catheter-related bloodstream infection caused by coagulase-negative staphylococci

Microbiological diagnosis of catheter-related bloodstream infection (CR-BSI) is often based on isolation of indistinguishable micro-organisms from an explanted catheter tip and blood culture, confirmed by antibiograms. Whether phenotypic identification of coagulase-negative staphylococci (CoNS) allows an accurate diagnosis of CR-BSI to be established was evaluated. Eight patients with a diagnosis of CR-BSI had CoNS isolated from pure blood cultures and explanted catheter tips which were considered as indistinguishable strains by routine microbiological methods. For each patient, an additional three colonies of CoNS isolated from the blood and five from the catheter tip were subcultured and further characterized by antibiogram profiles, analytical profile index (API) biotyping and PFGE. PFGE distinguished more strains of CoNS compared to API biotyping or antibiograms (17, 10 and 11, respectively). By PFGE, indistinguishable micro-organisms were only isolated from pure blood and catheter tip cultures in four out of eight (50%) patients thus supporting the diagnosis of CR-BSI. In another patient, indistinguishable micro-organisms were identified in both cultures; however, other strains of CoNS were also present. The remaining three patients had multiple strains of CoNS, none of which were indistinguishable in the tip and blood cultures, thus questioning the diagnosis of CR-BSI. Phenotypic characterization of CoNS lacked discriminatory power. Current routine methods of characterizing a limited number of pooled colonies may generate misleading results as multiple strains may be present in the cultures. Multiple colonies should be studied using a rapid genotypic characterization method to confirm or refute the diagnosis of CR-BSI. © 2007 SGM.