Identification of Staphylococcus epidermidis with transferrable mupirocin resistance from canine skin.

Resistance to mupirocin was analysed in Staphylococcus spp. isolated from healthy dogs (n=21) and dogs with pyoderma (n=47) or otitis externa (n=52). Isolates were identified to species level by MALDI-TOF and PCR-RFLP of the groEL gene. One isolate of Staphylococcus epidermidis from the skin of a healthy dog, which harboured a plasmid carrying the mupA gene, was resistant to mupirocin.

Characterization of Staphylococcus spp. strains in milk from buffaloes with mastitis in Brazil: the need to identify to species level to avoid misidentification / Caracterização de cepas de Staphylococcus spp. isoladas de leite de búfalas com mastites em Brasil: a necessidade de se identificar até nível de espécie para evitar erros de identificação

Mastitis is an inflammation of the mammary gland that affects dairy cattle worldwide causing economic losses. Coagulase-negative staphylococci (CNS) are the predominant cause of this type of infection. We have recently showed that coagulase-positive staphylococci could be misidentified. So, the aim of this study was to characterize the Staphylococcus spp. strains initially classified as coagulase-negative Staphylococci, isolated from buffalo with subclinical mastitis. Milk of buffaloes with mastitis in herds was collected and 9 strains were identified as CNS by phenotypic tests. Molecular methodologies latter identified the strains as coagulase-negative Staphylococcus chromogenes (5), coagulase-positive Staphylococcus hyicus (2) and coagulase-positive Staphylococcus aureus (2). Our results strongly support the need to identify the isolates to a species level in order to avoid misidentification and to be aware of the classification using the coagulase test alone.(AU)

A mastite é uma inflamação da glândula mamária que afeta o gado leiteiro em todo o mundo, causando perdas econômicas. Staphylococcus coagulase-negativa (SCN) são a causa predominante desse tipo de infecção. Mostrou-se recentemente que Staphylococcus coagulase-positiva podem ser identificados erroneamente. Assim, o objetivo deste estudo foi caracterizar cepas de Staphylococcus spp. inicialmente classificados como Staphylococcus coagulase-negativa, isolados de búfalas com mastite subclínica. O leite de búfalas com mastite foi coletado, e nove cepas foram identificadas como SCN por testes fenotípicos. Metodologias moleculares identificaram as cepas como Staphylococcus chromogenes coagulase-negativa (5) Staphylococcus hyicus coagulase-positiva (2) e Staphylococcus aureus coagulase-positiva (2). Os resultados reforçam a necessidade de identificar as cepas em termos de espécie, a fim de se evitarem erros de identificação e estar atento à classificação utilizando o teste de coagulase sozinho.(AU)

Staphylococcus haemolyticus as a potential producer of biosurfactants with antimicrobial, anti-adhesive and synergistic properties.

UNLABELLED: Staphylococcus haemolyticus is an opportunistic human pathogen that usually gains entry into the host tissue in association with medical device contamination. Biofilm formation is a key factor for the establishment of this bacterium and its arrangement and dynamics can be influenced by the synthesis of biosurfactants. Biosurfactants are structurally diverse amphiphilic molecules with versatile biotechnological applications, but information on their production by staphylococci is still scarce. In this work, two Staph. haemolyticus strains, showing high potential for biosurfactant production - as observed by four complementary methods - were investigated. Biosurfactant extracts were produced and studied for their capacity to inhibit the growth and biofilm formation by other bacterial human pathogens. The biosurfactant produced by the one of the strains inhibited the growth of most bacteria tested and subinhibitory concentrations of the biosurfactant were able to decrease biofilm formation and showed synergistic effects with tetracycline. Because these results were also positive when the biosurfactants were tested against the producing strains, it is likely that biosurfactant production by Staph. haemolyticus may be an unexplored virulence factor, important for competition and biofilm formation by the bacterium, in addition to the biotechnological potential. SIGNIFICANCE AND IMPACT OF THE STUDY: This work is the first to show the production of biosurfactants by Staphylococcus haemolyticus strains. Extracts showed antimicrobial, anti-adhesive and synergistic properties against a variety of relevant human pathogens, including the producing strains. In addition to the biotechnological potential, biosurfactants produced by Staph. haemolyticus are potentially undescribed virulence determinants in their producing strains.

Investigation of biotechnological potential of sponge-associated bacteria collected in Brazilian coast.

Marine bacteria are a rich source of structurally unique natural compounds, several of which have shown a wide variety of biological activities. In this study, the metabolites present in the culture supernatants of the eight sponge-associated bacteria were extracted using ethyl acetate, and all extracts showed activity against Staphylococcus aureus. Subsequently, the extracts of the Pseudomonas fluorescens H40 and H41, and Pseudomonas aeruginosa H51 were subjected to solvent partitioning, and the active fractions were submitted to chromatographic separation. Three different active fractions were obtained, one of which was identified as diketopiperazine cyclo-(L-Leu-L-Pro). This substance was bactericidal for Staph. aureus and Ps. aeruginosa and showed cytotoxic activity against HEp-2 tumour cells. Putative gene fragments coding for the type I polyketide synthase (PKS-I) and nonribosomal peptide synthetase (NRPS) domains were PCR-amplified from five and three strains, respectively. The results suggest that sponge-associated bacteria analysed in this study may represent a potential source for production of antimicrobial substances against bacterial pathogens of medical importance.

Reliability of the MicroScan WalkAway PC21 panel in identifying and detecting oxacillin resistance in clinical coagulase-negative staphylococci strains.

The purpose of this study was to determine the reliability of the MicroScan WalkAway PosCombo21 (PC21) system for the identification of coagulase-negative staphylococci (CNS) strains and the detection of oxacillin resistance. Using molecular and phenotypic methods, 196 clinical strains were evaluated. The automated system demonstrated 100 % reliability for the identification of the clinical strains Staphylococcus haemolyticus, Staphylococcus hominis and Staphylococcus cohnii; 98.03 % reliability for the identification of Staphylococcus epidermidis; 70 % reliability for the identification of Staphylococcus lugdunensis; 40 % reliability for the identification of Staphylococcus warneri; and 28.57 % reliability for the identification of Staphylococcus capitis, but no reliability for the identification of Staphylococcus auricularis, Staphylococcus simulans and Staphylococcus xylosus. We concluded that the automated system provides accurate results for the more common CNS species but often fails to accurately identify less prevalent species. For the detection of oxacillin resistance, the automated system showed 100 % specificity and 90.22 % sensitivity. Thus, the PC21 panel detects oxacillin-resistant strains, but is limited by the heteroresistance that is observed when using most phenotypic methods.

Aureocin A70 production is disseminated amongst genetically unrelated Staphylococcus aureus involved in bovine mastitis.

AIMS: The main aim of this study was to analyse the genetic relationship amongst 46 Staphylococcus aureus Bac(+) strains isolated in Brazil from 12 geographically distant dairy herds, including 34 isolates that produce the antimicrobial peptide aureocin A70. METHODS AND RESULTS: The comparison of 46 Staph. aureus Bac(+) strains was performed by pulsed-field gel electrophoresis (PFGE). Thirteen different pulsotypes were identified, and the subtype A(1) was the most prevalent one. Nine strains belong to pulsotype F, the second most prevalent and mostly confined to a single herd. The PFGE patterns of the 34 Staph. aureus aureocin A70-producers, isolated in Brazil, were also compared with those of strains isolated from bovine mastitis cases in Argentina and revealed that these strains are not genetically related. CONCLUSIONS: Although a previous study has suggested that a prevalent pulsotype of aureocin A70-producer Staph. aureus involved in bovine mastitis is disseminated in Argentina, this does not occur in Brazil. Additionally, it was possible to demonstrate that closely related staphylococcal strains can produce distinct staphylococcins. SIGNIFICANCE AND IMPACT OF THE STUDY: This study corroborates the hypothesis of horizontal gene transfer of aureocin A70 genes amongst distinct staphylococcal strains involved in bovine mastitis, giving them a selective advantage when colonizing the mammary glands.

Staphylococcus haemolyticus as an important hospital pathogen and carrier of methicillin resistance genes.

Phenotypic and molecular methods were used to characterize the antibiotic resistance of 64 clinical isolates of Staphylococcus haemolyticus. By PCR of the mecA gene, 87% were found to be methicillin resistant. Approximately 55% harbored staphylococcal cassette chromosome mec element (SCCmec) type V, and only one SCCmec type IV. Many isolates (75%) displayed multiresistance, and pulsotype analysis showed a high diversity.

Bacteriocins as alternative agents for control of multiresistant staphylococcal strains.

AIMS: To investigate the activity of seven staphylococcins, bacteriocins produced by staphylococci, against multiresistant Staphylococcus aureus and coagulase-negative staphylococci (CNS) involved in human infections. METHODS AND RESULTS: Four bacteriocins produced by Staph. epidermidis (Pep5, epidermin, epilancin K7 and epicidin 280) and three produced by Staph. aureus (aureocins A70, A53 and 215FN) were tested. Sixteen Staph. aureus strains, including a representative strain of the endemic Brazilian methicillin-resistant clone (MRSA), and 57 CNS strains were used as indicators. Among the staphylococcins used, Pep5 was able to inhibit 77.2% of the CNS strains and 87.5% of the Staph. aureus strains tested, including the Brazilian MRSA endemic clone, responsible for a large number of hospital-acquired infections in Brazil. On the other hand, aureocin A53 and epidermin presented a high antagonistic activity only against the Staph. aureus strains, being able to inhibit, respectively, 87.5% and 81.3% of them, including also the Brazilian MRSA endemic clone. The remaining bacteriocins inhibited only a low percentage of the nosocomial staphylococcal strains tested. CONCLUSIONS: Aureocin A53 and epidermin have potential applications against MRSA, whereas Pep5 seems to be an attractive agent against both MRSA and CNS, including mupirocin-resistant strains and the Brazilian endemic clone of MRSA, which is also found disseminated in other countries. SIGNIFICANCE AND IMPACT OF THE STUDY: Bacteriocins may represent alternative agents to control important nosocomial pathogens.

Protein synthesis inhibitory activity in culture filtrates from new strains of Streptomyces isolated from Brazilian tropical soils.

AIMS: To investigate the effect of the culture supernatants from three newly isolated Streptomyces strains, 221, 235 and 606 on eukaryotic cells. METHODS AND RESULTS: Cell lines were treated with the culture filtrates and assayed for protein synthesis by metabolic labelling, followed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis. RNA synthesis was investigated by [5-3H]uridine incorporation. The three culture filtrates presented a strong inhibitory activity, reducing total protein synthesis of different eukaryotic cell lines by more than 85%. No effect on cellular RNA synthesis was detected. The culture filtrates did not affect the growth of the prokaryotic cells tested. CONCLUSIONS: These new Streptomyces strains, recently isolated from Brazilian tropical soils, produce molecule(s) with inhibitory activity specific to eukaryote protein synthesis. SIGNIFICANCE AND IMPACT OF THE STUDY: Streptomyces strains 221, 235 and 606, probably representing new species, might produce new bioactive compound(s), and can be used as valuable tools to study the protein synthesis pathway in eukaryotes.

Expression of the major heat shock proteins DnaK and GroEL in Streptococcus pyogenes: a comparison to Enterococcus faecalis and Staphylococcus aureus.

One of the outstanding problems in the field of heat shock response has been to elucidate the mechanism underlying the induction of heat shock proteins (HSPs). In this work, we initiate an analysis of the expression of heat shock groEL and dnaK genes and their promoters in S. pyogenes. The synthesis of total cellular proteins was studied upon transfer of a log-phase culture from 37 degrees C to 42 degrees C by performing 5-min pulse-labeling experiments with (35)S-Met. The heat shock responses in the pathogenic Gram-positive cocci, Enterococcus faecalis and Staphylococcus aureus, were also analyzed.

Molecular characterization and transfer among Staphylococcus strains of a plasmid conferring high-level resistance to mupirocin.

In this work, mupirocin resistance was correlated with the presence of plasmids in methicillin-resistant Staphylococcus aureus (MRSA) strains isolated in the Rio de Janeiro Federal University Hospital in Brazil, where topical mupirocin has been used extensively since 1990. Of 19 strains studied, those exhibiting high-level resistance carried a large and relaxable plasmid of about 35 kb. Mupirocin-sensitive derivatives, obtained by growth at 42 C of a strain exhibiting high-level resistance, were devoid of the large plasmid, which was designated pMG1. Mupirocin resistance was transferred to strain RN8411 during overnight filter-matings at low frequencies (7.0 x 10(-9)/donor). The pMG1 plasmid was shown to be responsible for high-level mupirocin resistance in our isolates and to be incompatible with pGO1. Hybridization experiments suggested that mupirocin resistance in pMG1 is due to the presence of the ileS-2 gene. The pMG1 plasmid was successfully and bidirectionally transferred from Staphylococcus aureus to Staphylococcus epidermidis, suggesting that the latter may be a reservoir of this resistance plasmid. No transfer was detected to Staphylococcus haemolyticus. The development of self-transferable high-level mupirocin resistance should be considered when using mupirocin to control the spread of MRSA in hospitals.

Detection of ileS-2 gene encoding mupirocin resistance in methicillin-resistant Staphylococcus aureus by multiplex PCR.

The presence of the ileS-2 gene, responsible for mupirocin resistance, in clinical isolates of methicillin-resistant Staphylococcus aureus was determined by multiplex polymerase chain reaction. Three pairs of primers were used, which yielded specific fragments of femA (encoding a unique feature of S. aureus), mecA (encoding resistance to methicillin) and ileS-2 genes. The multiplex polymerase chain reaction system is an easy and time-saving technique that, together with a rapid method for DNA extraction by boiling, may be incorporated as a routine analysis in clinical diagnostic laboratories.

Expression of heat-shock proteins in Streptococcus pyogenes and their immunoreactivity with sera from patients with streptococcal diseases.

The heat-shock response of Streptococcus pyogenes following exposure to elevated growth temperatures, and the immunological reactivity of heat-shock proteins (HSPs) in streptococcal infections were studied. Two major proteins of 65 and 75 kDa were expressed when a S. pyogenes strain was shifted from 37 degrees C to heat-shock temperatures of 40, 42 and 45 degrees C. Such proteins are members of the GroEL and DnaK families recognised in a Western blot assay with polyclonal antibodies against Escherichia coli GroEL and E. coli DnaK, respectively. Two-dimensional autoradiograms of polypeptides labelled at 37 or 42 degrees C showed an increased intensity of three spots at 42 degrees C. A monoclonal antibody (MAb) against HSP 63 of Bordetella pertussis also recognised the 65-kDa inducible protein, although MAbs against Mycobacterium tuberculosis HSP 65 failed to recognise this protein. Immunoblot analysis of sera from individuals with rheumatic fever or uncomplicated streptococcal diseases revealed seven major immunogenic protein bands, two of which also reacted with anti-E. coli GroEL and DnaK polyclonal antibodies. Furthermore, antibodies to the GroEL and DnaK proteins were also detected in sera from patients with either rheumatoid arthritis or systemic lupus erythematosus. These results demonstrated a heat-shock response of S. pyogenes, and indicated the presence of an immune response against HSPs in streptococcal diseases.

Characterization and cellular distribution of heat-shock proteins HSP70 and HSP60 in Trypanosoma cruzi.

At least eight protein members of HSP70 and three of the HSP60 families have been identified in Trypanosoma cruzi; of these, five HSP70 isoforms and one HSP60 isoform were respectively induced by a 2-hr heat-shock treatment at 37 degrees C. Immunoelectronmicroscopy of epimastigote, spheromastigote, and metacyclic cells obtained in vitro showed anti-HSP60 reactive proteins in the mitochondria and near the kinetoplast. Anti-HSP70 reactive proteins presented a more complex pattern. They were observed in different cellular compartments, and after heat shock all the three cell forms analyzed presented gold particles associated with the cellular membrane.