Occurrence of Staphylococcus aureus enterotoxigenic strains isolated from pregnant women with pathology

137 S. aureus strains, isolated from the larynx of pregnant women in cases of pathology, were studied for the formation of staphylococcal enterotoxins of types A and B (SEA and SEB) by the indirect hemagglutination test. The study revealed that SEA was produced by 35.0% and SEB, by 56.6% of the strains under study. The proportion of SEA and SEB producers among staphylococci isolated from mothers and children was, respectively, 18.4% and 20.0%, 89.41% and 67.5%. The number of enterotoxigenic staphylococci in the upper respiratory tract of newborn infants and mothers practically coincided with that in mothers. The occurrence of SEA- and SEB-producing enterotoxigenic strains in the medical personnel was 25.5% and 62.7% respectively.     

Drug resistance of Staphylococcus aureus strains, isolated from children with intestinal dysbacteriosis

The level of antibiotic-sensitivity of 73 S. aureus strains isolated from children with dysbacteriosis of the large intestine in an outpatient clinic was determined. The isolation rate of polyresistant strains was 44%. Methicillin-resistant S. aureus (MRSA) were isolated from 25 children (34.2%). 60% of MRSA strains could not be typed with the international set of phages. Among the strains capable of being lyzed by the phages the representatives of phage groups 3 and 4 prevailed. All MRSA strains were sensitive to vancomycin, 84-88% of the strains were sensitive to chloroamphenicol, rifampicin, spiramycin and neomycin, 80% of the strains were sensitive to fusidin and phosphomycin. The level of sensitivity of methicillin-sensitive S. aureus strains (MSSA) to different groups of antistaphylococcal antibiotics was higher. 36-64% of MRSA strains and 21-27% of MSSA strains were resistant to the action of curative bacteriophages. The suppression of obligate microflora was the risk factor in the development of staphylococcal infection of the gastrointestinal tract in children.     

Detection and recovery of sublethally-injured enterotoxigenic Staphylococcus aureus

AIMS: To determine whether sublethally-injured (acid- or heat-shocked) Staphylococcus aureus cells are recoverable using selective agar overlays. METHODS AND RESULTS: Brain Heart Infusion (BHI) Agar overlaid with either Baird-Parker Agar (BPA) or Gram-Positive Agar (GPA) was compared in the ability to resuscitate heat- and acid-shocked enterotoxigenic Staph. aureus. BHI/BPA overlays allowed for greater recovery of both heat- and acid-shocked cells than BHI/GPA, although the former was not selective and allowed growth of bacteria other than Staph. aureus. No significant difference existed in percent recovery of heat- and acid-shocked cells between the two overlay approaches. Significant differences were noted in counts on BHI/GPA plates and straight selective GPA/GPA plates, however. Viability of heat- and acid-shocked Staph. aureus was also examined using fluorescence microscopy, the relative counts of which correlated well to the calculated percent recovery on selective agar overlays. CONCLUSIONS: This work has shown that an improved agar overlay technique increases the sensitivity of the standard plate count while enumerating sublethally-injured enterotoxigenic Staph. aureus compared with direct plating onto selective media. SIGNIFICANCE AND IMPACT OF THE STUDY: These data emphasize the need to develop practical and cost-effective methods that reliably detect and enumerate sublethally-injured pathogens such as Staph. aureus.     

Detection of enterotoxigenic Staphylococcus aureus isolates in raw milk cheese

AIM: To develop an easy, rapid and efficient DNA extraction procedure for Staphylococcus aureus detection with a low number of steps and removing completely the PCR inhibitors, applicable to raw milk cheese samples, and to compare phenotypical and genotypical method to detect Staph. aureus isolates and staphylococcal enterotoxins (SEs) production. METHODS AND RESULTS: A total of 33 bovine and caprine raw milk cheese samples were analysed by means of both classic microbiological and molecular techniques. All samples were positive for Staph. aureus contamination. The DNA extraction protocol optimized was found to achieve a detection limit of 100 CFU g(-1) for Staph. aureus. None of the samples tested with immunological assays contained SEs but in 14 of 33 samples a mixture of se positive (sea, sec, sed, seg, sel, sej) isolates were identified. CONCLUSIONS: Staphylococcus aureus is a food-borne pathogen mainly detected in finished dairy products. The rapid and efficient detection of Staph. aureus isolates from dairy products is essential for consumer safety. The direct detection of pathogens from food is possible with careful attention to sample preparation and nucleic acid amplification optimization. SIGNIFICANCE AND IMPACT OF THE STUDY: This study shows that raw milk cheese samples can be tested for Staph. aureus contamination with a rapid, simple and reproducible procedure.     

Antibiotic resistance and putative origin of Staphylococcus aureus and Klebsiella strains isolated from the children with intestinal dysbacteriosis

The results of the statistical treatment of data on the analyses of 766 children, the residents of Moscow, for dysbacteriosis are presented; of these children, 34 were aged up to 1 month and 732, from 1 month to 1 year. This study revealed that in the fist year of life in children with dysbacteriosis the dominating bacterial species were S. aureus, bacteria of the genus Klebsiella and fungi of the genus Candida. From the intestine of children aged up to 1 month S. aureus and Klebsiella were isolated more often than from children aged up to 1 year. The results of the study of antibioticograms demonstrated that 21.6% of S. aureus strains and 74.4% of Klebsiella strains were multiresistant to antibiotics. Taking into account the fact that multiresistance to antibiotics was characteristic of hospital strains, the suggestion was made that the isolated strains were of hospital origin and such strains could colonize the intestine of children in maternity hospitals.     

金黄色葡萄球菌儿童临床分离株携带PVL基因状况的分析

目的了解金黄色葡萄球菌儿童分离株携带Panton-Valentine杀白细胞素（PVL）基因的状况及感染类型。方法采用多重PCR同时检测金黄色葡萄球菌16SrRNA基因、PVL基因和mecA基因;多重PCR检测MR—SA的SCCmec基因型及亚型。结果66株金黄色葡萄球菌JL童临床分离株经多重PCR检测,其中MRSA有7株（10．6％）,MSSA有59株（89．4％）;携带PVL基因金黄色葡萄球菌有31株,总阳性率为47．O％（31／66）,其中2株为MRSA,29株为MSSA,阳性率分别为28．6％（2／7）和49。2％（29／59）。2株MRSA都属于SCCmecIV型;31株PVL基因阳性分离株有21株分离自脓液,7株分离自血液,仅1株分离自痰液。结论儿童MSSA是携带PVL基因的主要菌株,携带PVL基因的金黄色葡萄球菌主要引起化脓性感染和血流感染。     

Comparison of type A enterotoxigenic Staphylococcus aureus strains isolated from geographically far distant locations by pulsed field gel electrophoresis

Staphylococcal enterotoxin A (SEA) is one of the major staphylococcal enterotoxins which may cause food-borne outbreaks. In order to investigate the difference in genomic types and to elucidate the most disseminated strains for enterotoxin A-producing strains of Staphylococcus aureus , a total of 60 SEA Staph. aureus strains isolated from food and clinical samples in Taiwan and 30 strains of the same enterotoxigenic type of strains obtained from geographically far distant locations were compared for their pulsed field gel electrophoresis (PFGE) patterns. The rare cutting endonuclease Sma I generated 10 distinct genome patterns for the 60 local SEA isolates and 15 and eight genome patterns, respectively, for the 20 and 10 SEA strains originally isolated from the USA and other countries. The local isolates are less diverse in genome patterns as compared to the US isolates. Of all these PFGE patterns, a certain pattern, such as pattern 3, is shared by the food and clinical isolates and the local and foreign isolates. Thus, although SEA Staph. aureus strains from geographically far distant locations showed considerable genetic diversity, PFGE pattern 3 strain might be one of the most disseminated strains.     

Comparison of selective media for coagulase-positive enterotoxigenic Staphylococcus aureus.

Different culture media were used to detect enterotoxigenic Staphylococcus aureus strains from peptone salt solution and inoculated minced meat. When recovery, reactions, and counting mistakes were considered, it was concluded that Baird-Parker agar was the best medium.     

Proteomic analysis of exoproteins expressed by enterotoxigenic Staphylococcus aureus strains

Pathogenic bacteria excrete a variety of virulence factors into extracellular medium and to the cell surface which have essential roles in the colonization and insurrection of the host cells, and thus reflect the degree of bacterial pathogenicity. For the exploration of virulence factors expressed in the secreted proteome fraction, different Staphylococcus aureus strains were analyzed using gel-based bottom-up proteomic approach. A total of 119 distinct proteins were identified for the enterotoxin gene cluster (egc) negative and seb gene positive S. aureus American Type Culture Collection (ATCC) 14458 strain by the use of one- and 2-DE based proteomics. Detailed analysis of enterotoxin region of the 2-D map confirmed, beside the highly expressed staphylococcal enterotoxin B (SEB), the presence of enterotoxin-like proteins SElK and SElQ previously predicted by genotyping (Sergeev et al.., J. Clin. Microbiol. 2004, 42, 2134-2143). Exoprotein patterns at the late-exponential (7 h) and stationary (24 h) phases of cellular growth show a high-level similarity in this region. Comparative analysis of enterotoxin region of five S. aureus strains including two clinical isolates (RIMD 31092 and A900322), a food derived strain (AB-8802) with highly prevalent egc positive operon and a nonenterotoxigenic reference strain (ROS) revealed the presence of different known enterotoxins and other virulence factors along with a number of core exoproteins. In addition, production of SElL (RIMD 31092) and SElP (A900322) was demonstrated for the first time at the protein level. Under the experimental conditions applied none of the enterotoxins encoded by the genes of egc operon was identified.     

Biological characteristics of Staphylococcus aureus isolated from nude mice

The characteristics of 50 strains of Staphylococcus aureus isolated from BALB/c nude mice (nu/nu, nu/+) with or without subcutaneous abscesses [13] were examined. All the 50 strains belonged to biotype B according to the classification by Hájek and Marsálek. All of them were phage typable, showing a single phage pattern of 52A/79/47/53/77/83A/85. The coagulase type was classified as VII. All of the 50 strains were highly sensitive to penicillin, methylphenylisoxazolyl penicillin, erythromycin, spiramycin, lincomycin, chloramphenicol, tetracycline, kanamycin, gentamicin and cephaloridine, but were resistant to sulfisoxazole. Two S. aureus strains isolated from the nostril and finger of one person working in the mouse colony were identified as the same biotype as the murine strains but different in phage type, coagulase type and drug resistance pattern.     

A small cadmium resistance plasmid isolated from Staphylococcus aureus

We have isolated from Staphylococcus aureus a plasmid named pIP983, which measures 3.2 kb and specifies resistance to cadmium. The cad gene it carries is of the B type, as indicated by the level of resistance it confers on S. aureus and the sequence homology with the known cadB gene. Sequences homologous to pIP983 were found on several large S. aureus plasmids. They were localized close to the mcr region of pI/258 and pII147, and, at least in the case of the latter plasmid, were not contiguous, but interrupted by nonhomologous DNA.     

Biological properties of enterotoxigenic Escherichia isolated from patients with acute intestinal diseases of unknown etiology

As the result of the comparative examination of adult patients with acute enteric diseases and normal adults, 173 E. coli enterotoxigenic strains were isolated (161 strains from the patients and 12 strains from normal persons). 83% of the isolated enterotoxigenic E. coli (ETEC) produced two enterotoxins: thermolabile (LT) and thermostable (ST). Enterotoxigenicity was most pronounced in the strains of ETEC belonging to the prevaling variant ST + LT +. The enterotoxigenic properties of ETEC were highly stable: the production of ST and LT in the strains remained unchanged after their storage for up to 4 years. The isolated ETEC comprised 48 serogroups and 61 strains. The strains belonging to the same seroval had a similar degree of toxigenicity. The strains belonging to different serovars considerably differed in the activity of their enterotoxins. The production of two kinds of enterotoxins in the isolated E. coli strains was inter-related: the strains with a high activity of ST were, as a rule, good producers of LT.     

Clone of Staphylococcus aureus phage type 187 isolated from people

The aim of this study was to examine whether Staphylococcus aureus of phage type 187 are genetically homogenous with the use of digestion of chromosomal DNA with SmaI and separation of the DNA by pulsed-field gel electrophoresis (PFGE). Sixteen S. aureus phage type 187 were isolated from the hospital patients (12) and the healthy carriers (4) in twelve medical centres in Poland during 1991 and 2005. The PFGE typing proved that the phage type 187 isolates have the same PFGE type (except for one) and constitute one clone.     

Survey and properties of Staphylococcus aureus isolated from Japanese-style desserts

We surveyed the contamination of 315 Japanese- and western-style desserts and 247 human hands by Staphylococcus aureus and other staphylococcal bacteria. The most frequently isolated staphylococcal bacterium was S. warneri, followed by S. aureus. Only 1.9% of western-style desserts were contaminated by S. aureus strains, while 19.4% and 13.0% of Japanese-style desserts and human hands respectively were contaminated. Ninety-four isolates of S. aureus were characterized as to their biological properties and enterotoxigenicity. Although staphylococcal enterotoxins (SEs) were detected by enzyme-linked immunosorbent assay in the cultured broth of all S. aureus isolates, the reversed passive latex agglutination method and the polymerase chain reaction showed only 39 (41.5%) and 40 (42.6%) samples respectively as SE-positive. The predominant type of SE was SEB (67.5%), and eight strains produced SEA. None of the S. aureus strains had penicillin-binding protein 2', showing that methicillin-resistant S. aureus was not present in the samples.     

Adhesive proteins of haemagglutinating Staphylococcus aureus isolated from bovine mastitis

Two proteins derived from the cell wall of Staphylococcus aureus, exhibiting apparent molecular masses of 116 kDa and 145 kDa, were found to bind to human buccal and bovine lactiferous sinus epithelial cells. By using antibodies specific for fibronectin-binding protein of S. aureus of human origin, the 116 kDa protein, but not the 145 kDa protein, was identified as a fibronectin-binding protein. The 145 kDa protein bound to bovine fat globule membranes, human buccal epithelial cells, bovine lactiferous sinus epithelial cells and sheep erythrocytes. The properties of the 145 kDa protein suggest that it is an adhesin with a possible role in the early stages of the development of bovine mastitis.     

Genotyping of Staphylococcus aureus strains isolated from healthy persistent carriers

The paper presents results on the relatedness of Staphylococcus aureus strains colonizing the upper respiratory tract isolated from healthy persistent carriers. Genotyping was carried out using two methods—multiple-locus variable-number tandem-repeat fingerprinting (MLVF) and pulsed-field gel electrophoresis (PFGE). By comparison of the results obtained by both methods, good correlations between MLVF and PFGE genotyping of strains isolated from the asymptomatic carriers were observed. Further studies are needed to evaluate methods useful for genotyping of S. aureus strains circulating in the community.