Evaluation of survival of Staphylococcus aureus and Clostridium botulinum in charqui meats

Charqui meats were prepared in laboratory conditions in order to carry out experiments to observe the possibility of development of enterotoxigenic Staphylococcus aureus and Clostridium bottilinum proteolytic type B spores and their toxins. Results demonstrated that the harsh processing conditions, high salt concentration, relative high temperature, a, values, inhibited the growth of both bacteria. Under our experimental conditions, S. aureus would survive throughout the sequence of salting steps i.e. brine followed by rock salting and the sunshine drying step. However, at final a(w) value of 0.70-0.75 would create conditions to inhibit its development. The other experiment revealed that C. botulinum spores germination also was impaired because of these low a(w) values. Under these conditions, charqui meats revealed to be safe products in relation to toxins from both enterotoxigenic S. aureus and C. botulinum. (C) 2003 Elsevier B.V. Ltd. All rights reserved.

Charqui meats as fermented meat products: role of bacteria for some sensorial properties development

Jerked beef, a derivative of charqui meat, is a cured, salted and dried meat product. The presence of halotolerant bacteria, where Staphylococcus spp. (84.2%) were the predominant species, would act eventually as starter cultures and was followed throughout processing. Jerked beef prepared separately with exogenous S. carnosus and S. xylosus as starter cultures resulted in high proteolysis. Samples prepared with S. xylosus had the highest proteolysis and were preferred by the sensory panel. This research has suggested that jerked beef (and thus charqui meat) prepared under these conditions is a fermented meat product. (C) 2002 Elsevier B.V. Ltd. All rights reserved.

Staphylococcus aureus: Resistance patterns to antimicrobials and Penicillinase among strains isolated from apparently healthy lactating cows

Ninety-two strains of Staphylococcus aureus isolated from the nasal fossa and udder skin of apparently healthy lactating cows were analyzed for resistance to antibiotics and production of penicillinase.The results showed a greater frequency of resistance patterns to penicillin and ampicillin.All strains were sensitive to oxacyllin and gentamicin.The most frequent Barber and Burston model was SSSS (60.90%), followed by RSSS (18.50%).With respect to the production of penicillinase although the Lucas method indicated a larger number of positive samples, we suggest the use of the Haight and Finland method due to a greater consistency of data obtained with it.

COMPARATIVE INVITRO ACTIVITY OF 3 CEPHALOSPORINS AGAINST STAPHYLOCOCCUS-AUREUS ISOLATED FROM BOVINE MASTITIS

This report compares the in vitro activity of three cephalosporins (cephalothin, cefoxitin and ceftriaxone) against 57 Staphylococcus aureus strains isolated from cows with clinical mastitis on the basis of the minimal inhibitory (MIC) and minimal bactericidal concentrations (MBC). The majority of the S aureus strains showed resistance to cefoxitin and ceftriaxone and sensitivity to cephalothin. The highest MICs and MBCs were found for cefoxitin and ceftriaxone. Antimicrobial tolerance (MBC/MIC greater-than-or-equal-to 32:1) was observed in relation to cephalothin and ceftriaxone. The data suggest that these cephalosporins may not be effective for the treatment of staphylococcal bovine mastitis. The precise definition of their antimicrobial efficacies requires more detailed in vitro and in vivo studies.

IDENTIFICATION OF A PUTATIVE MEMBRANE-INSERTED SEGMENT IN THE ALPHA-TOXIN OF STAPHYLOCOCCUS-AUREUS

To gain a fuller understanding of the regions of the Staphylococcus aureus alpha-toxin important in pore formation, we have used Forster dipole-dipole energy transfer to demonstrate that a central glycine-rich region of alpha-toxin (the so-called ''hinge'' region) inserts deeply into the bilayer on association of toxin with liposomes. Mutant alpha-toxins with unique cysteine (C) residues at positions 69 and 130 [Palmer, M., et al. (1993) J. Biol. Chem. 268, 11959) were reacted with the C-specific fluorophore acrylodan, which acted as an energy donor. The chosen acceptor was N-(7-nitrobenz-2-oxa-13-diazol-4-yl)-1,2-bis(hexadecanoyl) -sn-glycero-3-phosphoethanolamine (NBD-PE). Measurement of the degree of donor quenching with increasing NBD-PE in the inner bilayer leaflet enables the distance of closest approach between donor and acceptor to be estimated. For toxin labeled with acrylodan at position 130 (in the hinge region), this distance is approximately 5 +/- 2 Angstrom, showing that the probe is close to the inner surface of the liposomes. A second probe labeled at position 69 (in the N-terminal domain) shows negligible energy transfer, indicating a distance of closest approach >40 Angstrom. This implies that this N-terminal region remains ''outside'' the liposome. We propose a model in which the central region of the alpha-toxin inserts into the membrane and possibly participates in forming the wall of the pore.

Análise fenotípica e molecular da produção de biofilmes por estirpes de staphylococcus aureus isoladas de casos de mastite subclínica bovina

Biofilm formation is considered an advantage for Staphylococcus aureus mastitis isolates, facilitating bacterial persistence in the udder. It requires attachment to mammary epithelium, proliferation and accumulation of cells in multilayers and enclosing in a polymeric matrix known as exopolysaccharide. The objective of this study was to evaluate the ability of Staphylococcus aureus isolated from bovine subclinical mastitis for formation of biofilms. A total of 94 Staphylococcus aureus strains obtained from milk samples of cows suffering from subclinical mastitis in dairy herds on two properties in the state of São Paulo were evaluated. These strains were characterized by in vitro biofilm formation, and by the presence of icaA and icaD genes which are responsible for intercellular adhesion. The results revealed that 98.9% of the isolates produced biofilm in vitro by adherence in sterile 96-well "U" bottom polystyrene tissue culture plates; 95.7% of the isolates possessed the icaA and icaD genes. These bacterial isolates biofilm producers may impair eradication of chronic mastitis, rendering antibiotherapy less effective. The detection of biofilm forming ability in mastitis isolates may provide useful information for more adequate therapeutic regimen and for preventive actions in the control of those bacterial isolates in bovine herds.

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.

Characterization of Staphylococcus aureus isolates in milk and the milking environment from small-scale dairy farms of São Paulo, Brazil, using pulsed-field gel electrophoresis

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

Minimum inhibitory concentrations of Staphylococcus aureus recovered from clinical and subclinical cases of bovine mastitis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Population analysis of susceptibility to propolis in reference strains of Staphylococcus aureus and Escherichia coli

Susceptibility to several ethanolic extracts of propolis (EEP) concentrations was tested with the population analysis technique in reference strains of Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 35218). The results of these tests showed that all bacteria were killed by EEP concentrations approximately equal or higher (2.0% v/v - S. aureus; 10.0% v/v - E. coli) than the respective minimal inhibitory concentrations (MIC). Regarding the susceptibility to propolis, there was a homogeneity of data with the respective time kill curves showing a clear bactericidal effect during 6 to 9 h of exposition.

Laminin-binding epitope on gp43 from Paracoccidioides brasiliensis is recognized by a monoclonal antibody raised against Staphylococcus aureus laminin receptor

Adhesion is regarded as an important step in the pathogenesis of several microorganisms. Thus, the ability to recognize extracellular matrix proteins, such as laminin or fibronectin, has been correlated with invasiveness. Studying the already characterized laminin-binding protein of Paracoccidioides brasiliensis, the 43 kDa glycoprotein (gp43), we evaluated whether MAb 1.H12, raised against the laminin-binding protein from Staphylococcus aureus, cross-reacts with that fungal protein. By immunoblot analysis we show that MAb 1.H12 recognizes gp43. This interaction is able to inhibit the laminin-mediated adhesion to epithelial cells as well as the P. brasiliensis infection in vivo. Moreover, through immunoenzymatic assays, we show that MAb 1.H12 recognizes gp43 in solid phase and that this interaction is partially inhibited by the addition of anti-gp43 MAbs. These results show that MAb 1.H12 recognizes the gp43, suggesting the presence of an epitope similar to those found in the other laminin-binding proteins from phylogenetically very distant cells. These findings reinforce the possibility of evolutionary conservation of such epitopes.

Ocorrência e determinação do perfil de sensibilidade às drogas das cepas de Staphylococcus aureus isoladas de fossas nasais e orofaringe dos servidores hospitalares

Staphylococcus aureus is a very important hospital and community pathogen. This species is related to supurative disease, systemic and widespread metastatic lesions. The ability of S. aureus to develop resistance to antibiotics, more recently to methicillin, associates this bacteria with epidemic outbreaks of severe nosocomial infection. The source of staphylococcal infection is a patient with a staphylococcal lesion or a career member of the hospital staff. We aimed to detect the frequency of S. aureus isolated from anterior nares and oral cavities among the hospital staff in Bauru - SP, and to determine the antibiotic susceptibility of the isolates. Within 213 of the staff members analyzed. S. aureus was found in 94 (44.13%) of careers, with 47 (50%) of nasal carriers, 23 (24.4%) of oral carriers and 24 (25.5%) of both carriers. The biochemical characteristics analyzed for the species identification were similar to S. aureus ATCC 29213. All strains identified as S. aureus showed varied sensibility to the antimicrobial agents tested. No vancomicin resistant strains and only 8 (8.5%) strains with oxacilin resistance were found.