Toxic Shock Syndrome Toxin-1 Gene Research Articles

MRSA clones identified in outpatient dermatology clinics

To know the characteristics of methicillin-resistant Staphylococcus aureus (MRSA) strains disseminating through the Japanese community, we have determined types of Staphylococcal cassette chromosome mec (SCCmec) elements, Multi-Locus Sequence Typing (MLST), and carriages of four exotoxin genes (toxic-shock syndrome toxin, Panton-Valentine Leukocidine, and exfoliative toxins a and b) using 54 MRSA strains isolated from outpatients attending dermatology clinics at the four university hospitals of Juntendo University. Ten clonal complexes and 12 SCCmec types have been identified. As a result, more than 15 MRSA clones that were defined by the combination of genotype and SCCmec type, were identified. Among them, Clonal Complex (CC) 5-type IIa SCCmec strains were the most major (16 strains). In contrast to the fact that CC5- type IIa SCCmec strains known as a hospital-associated MRSA clone in Japan carried toxic-shock syndrome toxin gene (tst), only 2 of 16 strains have been shown to carry tst. Thirty-eight (70.4%) of isolates belonged to the clones distinct from the CC5-type IIa SCCmec strains. Among them, CC8 strains were major (12 strains), which contained 9 tst-positive CC8-type IVl SCCmec clones and a CC8-type IVa SCCmec strain carrying the Panton Valentine Leukocidin gene (lukS, F-PV). Clones related to impetigo were also identified: 7 exfoliative toxin b (etb) -positive clones, CC89-type IIa SCCmec and CC89-type V SCCmec strains; and 2 exfoliative toxin a (eta) -positive CC121-type V SCCmec strains. Other clones were as follows: CC1-type IVa SCCmec, CC8-type I SCCmec, CC81-type IVg SCCmec, CC97-type IVc SCCmec, CC91-type IVa SCCmec, CC59-type IVg SCCmec, CC45-type IIn SCCmec, CC89-SCCmec nontypeable, and CC8-type IVm, novel subtype of type IV SCCmec were identified in this study. Our data showed that many novel MRSA clones have emerged in the community.

Characterization of SCCmectypes, antibiotic resistance, and toxin gene profiles ofStaphylococcus aureusstrains

Methicillin-resistant Staphylococcus aureus (MRSA) causes serious nosocomial and community acquired infections. Resistance to methicillin is mediated by the mecA gene, which is inserted in a mobile genetic element called staphylococcal cassette chromosome mec (SCCmec). We determined the SCCmec types, the occurrence of genes encoding toxic shock syndrome toxin (tst), exfoliative toxin (eta, etb), Panton-Valentine leukocidin (pvl) as well as antibiotic susceptibility of these isolates. Among 65 hospital-acquired methicillin-resistant S. aureus (HA-MRSA) strains, SCCmec types II, III and IV were identified. Type III SCCmec was the most prevalent (62%), followed by mec types II (24%) and IV (14%). Four community acquired methicillin-resistant S. aureus (CA-MRSA) strains carried SCCmec type IV and were pvl-positive. The most prevalent gene among HA-MRSA was pvl. The toxic shock syndrome toxin and exfoliative toxin genes were found only in hospital-acquired methicillin-resistant S. aureus. The results of this study demonstrate that the SCCmec type III is predominant among strains recovered from hospitalized patients with infections and that these strains were resistant to many antibiotics used in the treatment of staphylococcal infections.

Identification of Toxic Shock Syndrome Toxin-1 (TSST-1) gene in Staphylococcus aureus isolated from bovine mastitis milk

Staphylococcus aureus is a major causative pathogen of clinical and subclinical mastitis of dairy domestic ruminants. This agent produces a variety of extracellular toxins and virulence factors including Toxic Shock Syndrome Toxin-1 (TSST-1) which is the major cause of Toxic Shock Syndrome (TSS). In this study 58 S. aureus isolates obtained from 9 dairy herds in East and West Azerbaijan provinces of Iran. The tested isolates were identified on the basis of the cultural and biochemical properties as well as by amplification of the aroA gene, specific to S. aureus. Isolates were also analyzed for the presence of the TSST-1 encoding gene (tst) using Polymerase Chain Reaction (PCR). tst gene 350 bp was detected in 9 (15.5%) of the total number of 58 isolates. The present study revealed that the PCR amplification of the aroA gene could be used as a powerful tool for identification of S. aureus from the cases of bovine mastitis. Results also showed that the strain of S. aureus which caused mastitis can potentially produce staphylococcal toxic shock syndrome toxin-1. Overall, our results suggest that it is of special importance to follow the presence of TSST-1 producing S. aureus in foodstuffs, especially for protecting the consumers from toxic shock syndrome.

Leukocidin genes lukF-P83 and lukM are associated with taphylococcus aureus clonal complexes 151, 479 and 133 isolated from bovine udder infections in Thuringia, Germany

Staphylococcus aureus is one of the most important causal agents of bovine mastitis. Population studies on bovine Staphylococcus aureus isolates have identified considerable genetic heterogeneity among strains causing mastitis. The aim of this study was to investigate the contribution of different clonal complexes and the occurrence of virulence factors and resistance determinants within bovine Staphylococcus aureus isolates.A total of 189 Staphylococcus aureus isolates obtained from milk samples of 34 dairy herds in the German Federal State of Thuringia were characterised by microarray technology.The isolates were assigned to eleven different clonal complexes with CC151, CC479 and CC133 being dominant (together 80.5%). The methicillin resistance gene mecA was found in four isolates (2.1%), which belonged to CC398. Enterotoxin genes could be detected in 79.3% of analysed Staphylococcus aureus and 19 isolates (10.1%) harboured a distinct allele of the toxic shock syndrome toxin gene, tst-RF122. The most striking finding of the present study was that almost all except one isolate (151/152) belonging to CC151, CC479 and CC133 harboured the leukocidin genes lukF-P83 and lukM, whereas no further isolates from other lineages possessed these genes.The consistent occurrence of lukF-P83/lukM in the dominating clonal complexes suggests an essential role of this leukocidin in the etiology of bovine mastitis.

The emerging ST8 methicillin-resistant Staphylococcus aureus clone in the community in Japan: associated infections, genetic diversity, and comparative genomics

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) has become a major concern worldwide. In the United States, ST8 CA-MRSA with SCCmecIVa (USA300) has been predominant, affecting the entire United States. In this study, we investigated Japanese ST8 CA-MRSA with new SCCmecIVl (designated ST8 CA-MRSA/J), which has emerged in Japan since 2003. Regarding community spread and infections, ST8 CA-MRSA/J spread in 16.2-34.4% as a major genotype in the community in Japan, and was associated with skin and soft tissue infections (SSTIs), colitis, and invasive infections (sepsis, epidural abscesses, and necrotizing pneumonia), including influenza prodrome cases and athlete infections, similar to USA300. It spread to even public transport and Hong Kong through a Japanese family. Regarding genetic diversity, ST8 CA-MRSA/J included ST and spa variants and was classified into at least three pulsed-field gel electrophoresis types, ST8 Jα to γ. Of those, ST8 Jβ was associated with severe invasive infections. As for genomics, ST8 CA-MRSA/J showed high similarities to USA300, but with marked diversity in accessory genes; e.g., ST8 CA-MRSA/J possessed enhanced cytolytic peptide genes of CA-MRSA, but lacked the Panton-Valentine leukocidin phage and arginine catabolic mobile element, unlike USA300. The unique features of ST8 CA-MRSA/J included a novel mosaic SaPI (designated SaPIj50) carrying the toxic shock syndrome toxin-1 gene with high expression; the evolution included salvage (through recombination) of hospital-acquired MRSA virulence. The data suggest that ST8 CA-MRSA/J has become a successful native clone in Japan, in association with not only SSTIs but also severe invasive infections (posing a threat), requiring attention.

Analysis of Virulence Potentials of Community Acquired Staphylococcus aureus, Isolated from a Slam Population of West Bengal, India

–The worldwide spread of community acquired Staphylococcus aureus (CASA) skin infection is becoming an emerging problem. This study was conducted to delineate the virulence properties and characteristics of Staphylococcus aureus isolated from children belonging to low socio-economic classes in Midnapore town, West Bengal, India. Samples were collected from affected children by aseptic means from areas of infection with proper medical intervention. These samples were confirmed first as Staphylococcus aureus by PCR amplification of 16S rRNA. Further morphology, antibiotic susceptibility, capability of secreting several enzymes, biofilm forming abilities was studied. PCR was carried out for detection of the presence of enterotoxins (seA and seB), exfoliatin toxins (etA and etB) and toxic shock syndrome toxin (tssT) genes. Results reveal that 33% community acqured Staphylococcus aureus strains were methicillin resistant and 22% were vancomycin resistant and those strains were capable of biofilm formation. Besides, all of the pathogenic and non-pathogenic strains were harboring exfoliatin toxin gene (etA). So it can be concluded that inducible multidrug resistant community acquired Staphylococcus aureus with their diverse pathogenic toxic potentials giving emerging alarm in that geographical location in India. Keywords––Staphylococcus aureus, Staphylococcal Scalded Skin Syndrome, Staphylococcal toxins, vancomycin, biofilm.

Genotypes and Toxin Gene Profiles of Staphylococcus aureus Clinical Isolates from China

A total of 108 S. aureus isolates from 16 major hospitals located in 14 different provinces in China were characterized for the profiles of 18 staphylococcal enterotoxin (SE) genes, 3 exfoliatin genes (eta, etb and etd), and the toxic shock syndrome toxin gene (tsst) by PCR. The genomic diversity of each isolate was also evaluated by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and accessory gene regulator (agr) typing. Of these strains, 90.7% (98/108) harbored toxin genes, in which tsst was the most prevalent toxin gene (48.1%), followed by sea (44.4%), sek (42.6%) and seq (40.7%). The see and etb genes were not found in any of the isolates tested. Because of high-frequency transfer of toxin gene-containing mobile genetic elements between S. aureus strains, a total of 47 different toxin gene combinations were detected, including a complete egc cluster in 19 isolates, co-occurrence of sea, sek and seq in 38 strains, and sec and sel together in 11 strains. Genetic typing by PFGE grouped all the strains into 25 clusters based on 80% similarity. MLST revealed 25 sequence types (ST) which were assigned into 16 clonal complexes (CCs) including 2 new singletons. Among these, 11 new and 6 known STs were first reported in the S. aureus strains from China. Overall, the genotyping results showed high genetic diversity of the strains regardless of their geographical distributions, and no strong correlation between genetic background and toxin genotypes of the strains. For genotyping S. aureus, PFGE appears to be more discriminatory than MLST. However, toxin gene typing combined with PFGE or MLST could increase the discriminatory power of genotyping S. aureus strains.

Detection of stapylococcal enterotoxin, methicillin-resistant and Panton–Valentine leukocidin genes in coagulase-negative staphylococci isolated from cows and ewes with subclinical mastitis

Coagulase-negative staphylococci (CNS) are the most prevalent mastitis pathogens. However, virulence characteristics of CNS have not been well determined. The presence of genes for enterotoxins (sea-sej), toxic shock syndrome toxin-1 (tst), the exfoliative toxins (eta, etb), Panton-Valentine leukocidin (pvl) and mecA of CNS species isolated from cows and ewes with subclinical mastitis was investigated in this study. A total of 121 CNS (81 cows, 40 ewes) representing 18 different Staphylococci species were examined by PCR, and 38.1% (33 cows and 13 ewes) of CNS isolates had one or more se genes. The difference between percentages for SE toxin genes of CNS strains isolated from cows (40.7%) and ewes (32.5%) was not statistically significant (P > 0.05; χ(2) = 0.380). It was found that S. simulans isolates had the highest prevalent se genes. Furthermore, the most common SE gene types was seh-sej. In this study, none of the isolates harbored the toxic shock syndrome toxin gene (tsst) and the exfoliative toxin genes (eta, etb). Five cow (6.17%) and three ewe CNS (7.5%) isolates had mecA gene. Three cow (3.7%) and two ewe CNS (5.0%) isolates had pvl gene. In conclusion, the present study showed that CNS species isolated from cows and ewes could serve as potential reservoir of se, mecA, and pvl genes.

Fatal S. aureus hemorrhagic pneumonia: genetic analysis of a unique clinical isolate producing both PVL and TSST-1.

In 2008, an unusual strain of methicillin-sensitive Staphylococcus aureus (MSSA68111), producing both Panton-Valentine leukocidin (PVL) and toxic shock syndrome toxin-1 (TSST-1), was isolated from a fatal case of necrotizing pneumonia. Because PVL/TSST-1 co-production in S. aureus is rare, we characterized the molecular organization of these toxin genes in strain 68111. MSSA68111 carries the PVL genes within a novel temperate prophage we call ФPVLv68111 that is most similar, though not identical, to phage ФPVL – a phage type that is relatively rare worldwide. The TSST-1 gene (tst) in MSSA68111 is carried on a unique staphylococcal pathogenicity island (SaPI) we call SaPI68111. Features of SaPI68111 suggest it likely arose through multiple major recombination events with other known SaPIs. Both ФPVLv68111 and SaPI68111 are fully mobilizable and therefore transmissible to other strains. Taken together, these findings suggest that hypervirulent S. aureus have the potential to emerge worldwide.

Skin colonization by superantigen-producing Staphylococcus aureus in Egyptian patients with atopic dermatitis and its relation to disease severity and serum interleukin-4 level

The objective of the current study was to detect Staphylococcus aureus colonization and the presence of superantigen in atopic dermatitis (AD) in Egyptian patients, and to determine its effect on disease severity and serum interleukin (IL)-4 levels. Swabs were taken from the skin of 30 patients with AD. S. aureus isolates were screened for the presence of genes of exotoxins with superantigen properties by multiplex PCR. Serum IL-4 was determined by ELISA. The rate of S. aureus colonization and the presence of superantigen were correlated with disease severity and IL-4 level. Twenty-six of 30 patients (87%) were colonized by S. aureus, and 14 of the 26 (54%) patients were colonized with toxigenic strains. The most frequent superantigen gene present in S. aureus isolates was that coding for staphylococcal enterotoxin B (SEB), followed by both staphylococcal enterotoxin C (SEC) and toxic shock syndrome toxin-1 (TSST-1) genes. The mean 'severity scoring in AD' (SCORAD) score of AD patients colonized with S. aureus harboring superantigen genes (74 ± 8) was significantly higher than that in those colonized with S. aureus isolates without superantigen genes (56 ± 6) (p<0.001). Serum IL-4 levels followed the same pattern. S. aureus may play an important role as an aggravating factor in AD patients. Reducing the colonization of atopic skin by S. aureus is therefore the best way to reduce superantigen-induced allergic skin inflammation.

Distribution of newly described enterotoxin-like genes in Staphylococcus aureus isolated from ready-to-eat foods in Korea

To investigate the distribution of staphylococcal enterotoxin-like (SEl) genes in Staphylococcus aureus from food, a total of 154 S. aureus isolates from ready-to-eat (RTE) foods in Korea were analyzed by mutiplex PCR for the detection of the following 9 staphylococcal enterotoxin-like genes; sek, sel, sem, sen, seo, sep, seq, ser, and seu. Seventy-nine isolates (51.3%) were found to have at least one of SEl genes. The major SEl genes were sek, sem, sen, and seq. Other SEl genes found in the isolates were seo (21 isolates, 13.6%), seu (12 isolates, 7.8%), sep (8 isolates, 5.2%), sel (7 isolates, 4.5%), and ser (2 isolates, 1.3%). Most (95%) of the isolates with staphylococcal enterotoxin (SE) genes were also carried SEl genes. The genes seg, sei, sem, and sen were all detected in the same isolates. Ninety-seven % of isolates with seg+sei+sem+sen also contained seo or seu. Ninety-four % of isolates with sea+seh were found to coexist with sek+seq. The toxic shock syndrome toxin gene, tst-1, was found in all isolates with egc-2, including seg, sei, sem, sen, and seu. The coexistence of SE and SEl genes in S. aureus isolates from RTE foods can be explained by the mobile genetic elements. Because of the mobile genetic element, SE and SEl genes of S. aureus in foods may be transferable to nontoxigenic S. aureus and other food pathogens. Additional studies must be conducted to prevent spread of pathogenic genes such as enterotoxin gene.

Prevalence and Distribution of Superantigen Toxin Genes in Clinical Community Isolates of Staphylococcus Aureus

To investigate the distribution of twelve staphylococcal enterotoxin genes (se) and the toxic shock syndrome toxin-1 gene (tst) in Staphylococcus aureus, 140 community isolates from various origins were investigated. Isolates were collected, from 15 clinical laboratories located at Casablanca, between 2007 and 2008, they were identified by conventional methods, and methicillin resistance was confirmed by amplification of mecA gene by PCR. All isolates were searched using a multiplex PCR for the accessory gene regulator (agr) group, and for thirteen superantigen (SAg) toxin genes: sea, seb, sec, sed, seh, selk, sell, selm, selo, selp, selq, ser and tst. Among all isolates, only two were methicillin-resistant and one hundred seven were shown to be positive for at least one of the tested SAg toxin genes. They were grouped in 43 genotypes. Our work showed that agr group III and agr group I S. aureus isolates, were highly prevalent for the presence of seh, selq, selk and/or tst genes, on one hand, and sec and/or sell genes, on the other hand (P<0.05), respectively. In addition, we found a relationship between pus/ wound S. aureus isolates and the presence of selk + selq genes (P<0.05). Our results suggest that agr group III isolates carried more of SAg toxin genes than agr groups I and II S. aureus strains.

Superantigenic Toxin Genes Coexist with Specific Staphylococcal Cassette Chromosome mec Genes in Methicillin-Resistant Staphylococcus aureus

Staphylococcus aureus is a leading cause of human disease in the hospital setting and the community. Superantigenic toxin-producing methicillin-resistant Staphylococcus aureus (MRSA) is currently important for nosocomial infections and food-borne diseases worldwide because of its global spreading and difficulty in therapy. Superantigenic toxins can bypass normal antigen presentation and have strong T cell mitogenic activity, leading to massive release of proinflammatory cytokines and contributing to the severity of S. aureus sepsis. In this study, a total of 131 MRSA isolates from patients in the University Hospital were searched for staphylococcal cassette chromosome mec (SCCmec) genes and the staphylococcal superantigenic toxin genes by multiplex polymerase chain reactions. The MRSA isolates were classified into SCCmec type II (74.8%), type I (13.0%), type IV (3.8%), type V (2.3%), and type I and type II (3.8%). MRSA isolates (102/131) also carried a number of superantigenic toxin genes including staphylococcal enterotoxin (se) and toxic shock syndrome toxin-1 (tst-1) genes. The most frequent superantigen gene profile (55/131, 42.0%) of the MRSA isolates includes staphylococcal enterotoxin C (sec), seg, sei, staphylococcal enterotoxin-like L (sell), selm, seln, selo, and tst-1. Furthermore, SCCmec type I or type II MRSA isolates more frequently harbor sec, seg, sei, sell, selm, seln, selo, and tst-1 genes, compared to other types of MRSA. These results indicate that the selected superantigenic toxin genes are linked to SCCmec type I and type II. The coexistence of these toxins and the SCCmec genes in S. aureus may contribute to the biological fitness and pathogenicity of MRSA.

Detection of some virulence factors in Staphylococcus aureus isolated from clinical and subclinical bovine mastitis in Iran

Mastitis is one of the common diseases of dairy cattle and an inflammatory response of the mammary glands tissue. Mastitis causes considerable loss to the dairy industry. Among several bacterial pathogens that can cause mastitis, Staphylococcus aureus is probably the most lethal agent because it causes chronic and deep infection in the mammary glands that is extremely difficult to be cured. The present study was to detect some of the virulence factors in the S. aureus isolated from 360 mastitis milk samples in Chaharmahel va Bakhtiari and Isfahan provinces of Iran via PCR by using specific primers. Among a 360 raw milk samples, 86 samples contained 1250 bp fragment of the 23srRNA gene, 42 samples contained coa gene, 63 samples contained clfA gene, 69 samples contained IgG binding region gene, 22 samples contained X region coding gene protein A, 3 sample contained Toxic shock syndrome toxin gene (tst), 16 samples contained the exfoliative toxin A and B genes, 10 samples contained agrI gene, 42 samples contained agrII gene, 19 samples contained agrIII gene and 15 samples contained agrIV gene.

Investigation of Toxin Genes by Polymerase Chain Reaction inStaphylococcus aureusStrains Isolated from Bovine Mastitis in Turkey

Staphylococcus aureus causes a number of diseases in humans and animals, and it is the most common etiological agent of contagious bovine mastitis. The agent produces several virulence factors such as coagulase (coa), clumping factor, protein A, exfoliative toxins, staphylococcal enterotoxins (SEs), and toxic shock syndrome toxin-1. The aim of the present study was to characterize coa-positive S. aureus strains (n = 92) isolated from bovine subclinical mastitis in Turkey by polymerase chain reaction (PCR) amplification of exfoliative toxin (eta and etb) and toxic shock syndrome toxin-1 (tsst) genes. In addition, a multiplex PCR was employed to investigate the presence of SE genes sea, seb, sec, sed, see, seg, seh, sej, and sei. By PCR amplification, while eta and etb were not detected, only three isolates (3.3%) were positive for tsst. Twenty-seven (29.3%) isolates harbored one or more SE genes, and sei was the most common pattern by multiplex PCR. None of the isolates harbored the genes encoding sea, see, and seh. The application of this multiplex PCR assay could enable more samples to be rapidly characterized for enterotoxin production of S. aureus isolates from milk for epidemiological studies.

Molecular epidemiology of Staphylococcus aureus in asymptomatic carriers

Microarrays were used to extensively characterise 155 Staphylococcus aureus isolates obtained from asymptomatic carriers from Saxony, Germany, in order to determine clonal complex affiliation, as well as the carriage of clinically relevant genes. Isolates belonged to 20 different clonal complexes (CCs). The most common CC was CC8 (18.71%), followed by CCs 15, 30 and 45. Three isolates (1.94%) were methicillin-resistant S. aureus (MRSA). Beta-lactamase was common (70.97%), but other resistance genes were found only sporadically. Genes encoding superantigens were abundant. The enterotoxin cluster egc was found in 45.81% of isolates. The toxic shock syndrome toxin gene tst was detected in 14.84% of isolates and 17.42% harboured enterotoxin A alleles (sea, sea-N315). Contrarily, Panton-Valentine leukocidin (lukS/F-PV) was rare, being found in only one methicillin-susceptible CC30 isolate. Its low prevalence in asymptomatic carriers might emphasise a pathogenetic significance in patients with skin and soft tissue infections. Most microbial surface components recognising adhesive matrix molecules of the host (MSCRAMMs) genes were nearly ubiquitously present. However, two MSCRAMM genes, cna (collagen adhesion) and sasG (surface protein G), were detected in only some CCs. These data provide an insight into its pathogenesis, especially when compared to isolates from patients with defined clinical conditions. They might also be helpful for the design of a future vaccine.

MALDI-TOF-MS for rapid detection of staphylococcal Panton–Valentine leukocidin

Toxin-producing Gram-positive bacteria are responsible for emerging and life-threatening infections in humans worldwide. Both rapid toxin detection and adapted therapy are essential to limit the morbidity due to such toxins, especially staphylococcal Panton–Valentine leukocidin (PVL). Here we describe the use of a mass spectrometry profile generated by matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) followed by ClinProTools™ 2.0 software analysis to find a reproducible model able to identify PVL in Staphylococcus aureus strains. Eighty-one S. aureus strains were used and tested for the presence of PVL, toxic shock syndrome toxin (TSST-1) and mecA genes. The peak at 4448 mass-to-charge ratio ( m/ z) was the most relevant peak to differentiate between PVL-producing and non-PVL-producing S. aureus. A model using only this peak had an overall recognition capability of 100% and an overall cross-validation of 77.07%. Prospective evaluation of the model allowed two cases of PVL-producing strains to be detected within a few minutes during the time of care and before polymerase chain reaction (PCR) results. Our study represents a proof of concept for the use of such rapid technology as a point-of-care method to identify potential lethal toxin quickly. We believe that such a rapid method will be timely to help change the therapeutic strategy and could be used in the future for other pathogens and infectious diseases.

Staphylococcus aureus of phage type 187 isolated from people occurred to be a genes carrier of eneterotoxin C and toxic shock syndrome toxin-1 (TSST-1)

The aim of this study was to examine the genotype properties of Staphylococcus aureus of phage type 187 strains that constitute a separate group among the strains of S. aureus. Sixteen strains were collected from the hospital patients (n=12) and the healthy carriers (n=4) in 13 medical centres in Poland during 1991 and 2005. Biotyping, antibiotic susceptibility, phage typing, detection the genes of enterotoxins and toxic shock syndrome toxin, genotyping of chromosomal DNA by pulsed-field gel electrophoresis (PFGE), also amplification and restriction analysis of the coagulase (coa) and the protein A genes (spa) (PCR/restriction fragment length polymorphism (RFLP)) was tested. The results of this study showed that all staphylococcus of phage type 187 belonged to the human biotype (A) and appeared to be sensitive to all of the tested antibiotics, including methicillin (MSSA). Finding out the toxin genes showed that almost all of them (93.8%) had the enterotoxin C gene (sec) and TSST-1 gene (tst). The PFGE typing proved that the phage type 187 strains (except for one) constitute one PFGE type. These results and the identical restriction patterns in the PCR/RFLP method, also the same biotype, sensitivity to antibiotics and the presence genes of the same type of toxins confirmed that the phage type 187 strains constitute one clone within our country. Additionally, the fact that almost all of them have the enterotoxin genes and tst gene allows to consider them the strains of potentially high virulence.

Molecular Epidemiology of Methicillin-Resistant Staphylococcus aureus Isolates with Toxic Shock Syndrome Toxin and Staphylococcal Enterotoxin C genes

Many methicillin-resistant Staphylococcus aureus (MRSA) isolates in Korea possess a specific profile of staphylococcal enterotoxins in that the toxic shock syndrome toxin gene (tst) coexists with the staphylococcal enterotoxin C gene (sec). Because the analysis of staphylococcal cassette chromosome mec (SCCmec), a mobile genetic element mecA gene encoding methicillin resistance, showed that majority of these are SCCmec type II, these MRSA isolates with tst and sec may be genetically related with each other. This study was performed to investigate the genetic relatedness of tstand sec-harboring MRSA strains isolated in Korea by using pulsed-field gel electrophoresis (PFGE). A total of 59 strains of MRSA isolates of SCCmec type II possessing tst and sec were selected for PFGE and phylogenetic analyses. These isolates were collected from 13 health care facilities during nationwide surveillance of antimicrobial resistance in 2002. The 59 MRSA isolates were clustered into 11 PFGE types, including one major group of 26 strains (44.1%) isolated from 7 healthcare facilities. Seven PFGE types contained 2 or more isolates each, comprising 55 isolates in total. Most of SCCmec type II MRSA isolates containing tst and sec showed closely related PFGE patterns. Moreover, MRSA isolates collected from different healthcare facilities showed identical PFGE patterns. These findings suggested a clonal spread of MRSA strains possessing tst and sec in Korean hospitals.

Prevalence of Enterotoxin and Toxic Shock Syndrome Toxin Genes inStaphylococcus aureusIsolated from Milk of Cows with Mastitis

Staphylococcus aureus isolated from milk of cows with mastitis were evaluated for the prevalence of 16 enterotoxin genes (sea-see and seg-seq) and toxic shock syndrome toxin gene (tsst-1). Of 78 S. aureus examined, 73 (93.6%) were positive for one or more enterotoxin genes and these were divided into 36 groups by the presence of different enterotoxin genes. Enterotoxin genes including sen (84.6%), sem (71.8%), sei (60.3%) and sed (52.6%) were found frequently, while seg (24.4%), seq (16.7%), seo (12.8%), and seb (1.3%) were found at lower frequencies. Toxic shock syndrome toxin (tsst-1) gene was detected in 20 (25.6%) isolates and was always found in combination with other enterotoxin genes. The majority (88.5%) harbored more than one enterotoxin gene in different combinations. Eight S. aureus isolates (10.3%) were positive for sed, sei, sem, and sen; six (7.7%) possessed sed, seg, sei, sem, sen, and tsst-1; five (6.4%) had sei, sem, and sen; and four (5.1%) had sei, and sen. One isolate was positive for seb along with other SE genes including sed, seh, sem, sen, seq, and tsst-1. None of the isolates carried other enterotoxin genes (sea, sec, see, sej, sek, sel, and sep). PFGE profiles revealed 15 distinct pulsotypes among the 78 S. aureus isolates evaluated. PFGE and enterotoxin gene profiles did not match with each other because a single pulsotype carried different combinations of enterotoxin genes. The majority of S. aureus isolated from milk of mastitic cows carried newly described SE genes sem, sen and sei along with classical SE genes, sed and tsst-1. This is the first report describing the high prevalence of newly described enterotoxin genes, sem and sen in S. aureus from bovine mastitis. The high prevalence of enterotoxin genes and tsst-1 in S. aureus may be important as it is relevant to udder pathogenicity and food hygiene.