Inhibitory effect of bacterial attachment on candidal growth due to adherence with mannose-sensitive pili

Antibiotic resistance and pathogenicity factors in Staphylococcus aureus isolated from mastitic Sahiwal cattle

Methicillin-resistant Staphylococcus aureus (MRSA) poses a serious problem in dairy animals suffering from mastitis. In the present study, the distribution of mastitic MRSA and antibiotic resistance was studied in 107 strains of S. aureus isolated from milk samples from 195 infected udders. The characterizations pathogenic factors (adhesin and toxin genes) and antibiotic susceptibility of isolates were carried out using gene amplification and disc diffusion assays, respectively. A high prevalence of MRSA was observed in the tested isolates (13.1%). The isolates were also highly resistant to antibiotics, i.e. 36.4% were resistant to streptomycin, 33.6% to oxytetracycline, 29.9% to gentamicin and 26.2% each to chloramphenicol, pristinomycin and ciprofloxacin. A significant variation in the expression of pathogenic factors (Ig, coa and clf) was observed in these isolates. The overall distribution of adhesin genes ebp, fib, bbp, fnbB, cap5, cap8, map and cna in the isolates was found to be 69.1, 67.2, 6.5, 20.5, 60.7, 26.1, 81.3 and 8.4%, respectively. The presence of fib, fnbB, bbp and map genes was considerably greater in MRSA than in methicillin-susceptible S. aureus (MSSA) isolates. The proportions of toxin genes, namely, hlb, seb, sec, sed, seg and sei, in the isolates were found to be 94.3, 0.9, 8.4, 0.9, 10.2 and 49.5%, respectively. The proportions of agr genes I, II, III and IV were found to be 39.2, 27.1, 21.5 and 12.1%, respectively. A few isolates showed similar antibiotic-resistance patterns, which could be due to identical strains or the dissemination of the same strains among animals. These findings can be utilized in mastitis treatment programmes and antimicrobials strategies in organized herd.

Pheno and genotyping ofStaphylococcus aureus, isolated from bovine milk samples from São Paulo State, Brazil

In the present study, 87 Staphylococcus aureus isolates obtained from milk samples of 87 cows with mastitis in 6 different municipal districts of 2 regions of São Paulo State, Brazil, were compared pheno and genotypically. Pulsed-field gel electrophoresis (PFGE) analysis of the strains was performed, and PCR was carried out to detect genes for a number of staphylococcal cell surface proteins, exoproteins, and 3 classes of agr genes. Nine distinct S. aureus lineages (LA–LI) were identified by PFGE. The lineages LA and LE, which accounted together for 63 strains (72.2%), were prevalent and had been collected from all of the 6 municipal districts, indicating a broad geographic distribution of these lineages; LB, LC, LD, LF, LG, LH, and LI, however, were isolated sporadically and accounted for 24 strains (27.8%). Some characteristics, like penicillin resistance and the presence of cap8 and agr class II genes, were associated with the prevalent lineages (LA and LE), and penicillin susceptibility and the presence of cna and cap5 genes were associated with sporadic lineages. According to the present results, some S. aureus lineages possess a combination of genes that confer the propensity to cause and disseminate infection, and only a limited number of clones are responsible for the cases of bovine mastitis on the various farms.Key words: S. aureus, mastitis, phenotyping, genotyping.

Bacterial flora accompanying Candida yeasts in clinical specimens

From 1986 to 1988, in the prefluconazole era, 67,765 clinical specimens from the Göttingen University Hospital were investigated for bacteria and fungi in our institution. Oral and throat swabs, respiratory secretions, gastric juices, faeces, urine, genital swabs, blood, wound secretions and skin swabs were analysed for yeast-like fungi, and opportunistic or pathogenic bacteria. A total of 5195 specimens (7.7%) yielded Candida spp. alone or in combination with bacteria (fungal (F-) group) and 62,570 specimens yielded bacteria only or remained sterile (non-fungal group, N-group). Elevated rates of accompanying bacteria were detected with Candida spp. colonizing blood, urine, and skin. Among the dominant bacterial isolates, the distribution of staphylococci and enterococci did not reflect a distinct association pattern. Among the enterobacterial isolates from patients in intensive care, colonization patterns of the throat, gastric juices, and faeces reflected the use of a selective decontamination of the digestive tract (SDD). A statistically significant association between Candida and enterobacteria of the genus Enterobacter which was unaffected by SDD, was observed throughout this study. Such an association pattern was also observed, to a lesser extent, with the related genera Klebsiella and Serratia, but not with Escherichia coli.