Prevalence of Exfoliative and Toxic Shock Syndrome Toxin Genes in Methicillin-resistant Staphylococcus aureus Strains Isolated from Clinical Specimens in Makkah, Saudi Arabia.

The emergence of methicillin-resistant Staphylococcus aureus (MRSA) strains possessing virulence genes encoding such toxins as exfoliative toxins (ETs), toxic shock syndrome toxin-1 (TSST-1), is worrying, especially in relation to the increasing frequency of nosocomial infections. The present study aimed to determine the prevalence of genes encoding ETs and TSST-1 in MRSA isolates by polymerase chain reaction (PCR). The results showed that out of 88 investigated MRSA isolates, tst and etb toxin gene were found in 3 (3.4%) and 2 (2.3%) respectively, while none eta toxin genes were detected. It was concluded that the incidence of ET and TSST-1encoding genes among MRSA isolates in Makkah is lower or near to the global prevalence.

Prevalence of Antibody to Toxic Shock Syndrome Toxin-1 in Burn Patients

BACKGROUND: Burn wounds lack normal barriers that protect against pathogenic bacteria, and burn patients are easily colonized and infected by Staphylococcus aureus. Toxic shock syndrome (TSS) is a rare but fatal disease caused by S. aureus. A lack of detectable antibodies to TSS toxin-1 (TSST-1) in serum indicates susceptibility to TSS. METHODS: A total of 207 patients (169 men and 38 women; median age, 42.5 yr) admitted to a burn center in Korea were enrolled in this study. The serum antibody titer to TSST-1 was measured by sandwich ELISA. S. aureus isolates from the patients' nasal swab culture were tested for TSST-1 toxin production by PCR-based detection of the TSST-1 toxin gene. RESULTS: One hundred seventy-four (84.1%) patients showed positive results for antibody against TSST-1. All patients aged > or =61 yr (n=28) and <26 months (n=7) were positive for the anti-TSST-1 antibody. S. aureus was isolated from 70 patients (33.8%), and 58.6% of the isolates were methicillin resistant. Seventeen patients were colonized with TSST-1-producing S. aureus. The antibody positivity in these 17 carriers was 88.2%, and the positivity in the non-carriers was 83.7%. CONCLUSIONS: Most burn patients had antibody to TSST-1, and nasal colonization with TSST-1-producing S. aureus was associated with positive titers of anti-TSST-1 antibody. Additionally, patients with negative titers of anti-TSST-1 antibody might be susceptible to TSS.

Ampicillin alone and in combination with riboflavin modulates Staphylococcus aureus infection induced septic arthritis in mice.

Effects of ampicillin (Amp) in combination with riboflavin on septic arthritis in mice infected with Staphylococcus aureus have been reported. Ampicillin was given at 100 mg/kg after 24 h of infection, followed by riboflavin (Ribo) at 20 mg/kg body wt, after 2 h of Amp treatment. Mice were sacrificed at 3, 9, 15 days post infection (dpi). Combined treatment of infected mice with ampicillin and riboflavin eradicated the bacteria from blood, spleen and synovial tissue and showed a significant gross reduction in arthritis, reduced serum levels of TNF- and IFN-. S. aureus infected mice exhibited higher synovial TNF- and IL-6, which was also reduced by ampicillin and riboflavin treatment. S. aureus infected mice showed a disturbed antioxidant status measured in terms of cellular anti-oxidants like reduced glutathione and anti-oxidant enzymes such as superoxide dismutase and catalase and were ameliorated when the animals were co-treated with ampicillin along with riboflavin. Results of the study showed that combined treatment with anti-oxidant and antibiotic may protect from staphylococcal arthritis and may ameliorate oxidative stress caused by S. aureus infection.

Correlation Between the Prevalence of Superantigenic Toxin Genes and Coagulase Serotypes of Staphylococcus aureus Isolates

A heterogenic group of staphylococcal exotoxins, including staphylococcal superantigenic toxins, enterotoxin (SE), toxic shock syndrome toxin-1 (TSST-1), and coagulase are the most important virulence factors of Staphylococcus aureus. We analyzed the prevalence of genes encoding five enterotoxins and TSST-1 in S. aureus isolated from clinical ear discharges. The genes were identified by multiplex PCR and we compared the results to references of coagulase serotypes. In 102 isolates of S. aureus, 44 of them were methicillin-resistant S. aureus (MRSA) and the others were methicillin-susceptible S. aureus (MSSA). Among both types of S. aureus, 33 strains were positive for sea, 2 for seb, 23 for sec, 26 for see, and 26 for tst. Overall, 59 (57.8%) isolates were positive for one or more superantigenic toxin genes. From these, 71.2% (42/59) strains harbored more than one toxin gene in different combinations. The major combinations of genes were sea and see, and sec and tst. The degree of possession of superantigenic toxic genes was similar in both MRSA and MSSA isolates (56.8% vs 58.6%, respectively), yet significant differences in toxin gene profiles and coagulase serotypes between two isolates were detected. All of 13 positive strains for sec and tst were MRSA and belonged to coagulase serotype II. On the other hand, 80.0% of 20 positive strains for sea and see were MSSA with coagulase serotype IV and VII, whereas 20.0% of them were MRSA with coagulase serotype IV. This data indicates that the profile of superantigenic toxin genes correlates to coagulase serotype and methicillin resistance in S. aureus isolates.

Analysis of antibiotic-resistant gene mecA and pathogenic genes in Staphylococcus aureus / 中国感染与化疗杂志

Objective To investigate the antibiotic-resistant gene mecA and the prevalence of Panton-Valentine leukocidin (PVL) gene, toxic shock syndrome toxin (TSST-Ⅰ) gene in S. aureus. Methods A total of 74 S. aureus were collected from clinical specimens. The mecA, PVL and TSST-Ⅰ genes were detected by PCR.Results PVL gene was identified in 22 S. aureus isolates. The prevalence of PVL was 29.7% in S. aureus, 36.6% in MRSA and 21.2% in MSSA. The difference was not statistically significant (P>0.05). The prevalence of MRSA was 55.4% in 74 S. aureus. The prevalence of TSST-Ⅰ gene was 6.8%. TSST-Ⅰ gene was not detected in MSSA.Conclusions MRSA strains show highly resistant to antibiotics. PVL- and TSST-Ⅰ-positive S. aureus are more pathogenic.

Investigation on toxic shock syndrome toxin 1 from Staphylococcus aureus / 中华微生物学和免疫学杂志

Objective To detect the mecA gene and tst gene of toxic shock syndrome toxin 1 (TSST-1)of Staphylococcus aureus by using PCR and to learn the carrier condition of tst gene.Methods The mecA gene and tst gene of Staphylococcus aureus strains that isolated from clinical sources in our hospital during August 2006 to May 2007 were amplified in vitro using PCR,and to establish the rapid,specific,and sensitive method of detecting tst gene of methicillin resistant Staphylococcus aureus(MRSA).Results The mecA gene and tst gene were detected,and were made the gene sequencing successfully.Forty-one of 84 strains had mecA gene(48.81%),16 of 84 strains had tst gene(19.05%),10 of 84 strains had both of them,and the positive rate was 24.39%(10/41).Conclusion The proportion of tst gene positive strains of MRSA iS high in clinic,and it must be paid more attention.

Production and Characterization of Anti-Staphylococcal Toxic Shock Syndrome Toxin-1 Monoclonal Antibody / 대한진단검사의학회지

BACKGROUND: Recently the association between the virulence factors of Staphylococcus aureus and the outcome of the patients infected with the organism appears to be the subject of active investigation. Toxic shock syndrome toxin-1 (TSST-1) is thought to be a clinically more significant virulence factor than other staphylococcal toxins. We attempted to produce and characterize monoclonal antibodies to staphylococcal TSST-1. METHODS: An important epitope of TSST-1, amino acids 1-15 region, was synthesized into a peptide antigen, and Balb/c mice were immunized by intraperitoneal injection of the synthetic antigen. Hybridomas were produced by fusing immunized murine splenocytes with immortal myeloma cells. Hybridomas were cloned through a limiting dilution method. Stable cultured hybridoma was injected into the peritoneal cavity of Balb/c mice, and peritoneal fluid containing the monoclonal antibody was produced. RESULTS: One IgG2b type monoclonal antibody and two IgM type monoclonal antibodies were obtained. The IgG2b type monoclonal antibody was able to detect 5 microgram of TSST-1 with Western blot analysis and showed a strong reactivity to TSST-1 with ELISA. CONCLUSIONS: Highly immunoreactive anti-TSST-1 monoclonal antibody was produced by the use of synthesized peptide antigen. Diagnostic and protective capacity of this monoclonal antibody should be evaluated in the future.

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

BACKGROUND: 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). METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Single Clone of Toxic Shock Syndrome Toxin 1-Producing Methicillin-Resistant Staphylococcus Aureus Isolated from a Neonatal Intensive Care Unit Patients / 대한임상미생물학회지

BACKGROUND: Six babies infected with Staphylococcus aureus occurred in a neonatal intensive care unit (NICU) over a period of 2 months, which was successfully controlled with the aid of moleculartyping of the isolates. METHODS: We examined the staphylococcal toxins, mecA and tst gene PCR, and repetitive-element PCR (rep-PCR) typing in S. aureus isolated from the clinical specimens of infected babies, nasal swabs of the patients and medical personnels in a NICU, and environmental equipments. RESULTS: Among all S. aureus isolates tested, they were toxic shock syndrome toxin 1 (TSST-1)- producing methicillin-resistant S. aureus (MRSA) who have mecA and tst gene, and one identical rep- PCR pattern all, except 3 MRSA isolated from the nasal swabs of 2 non-infected patients and 1 medical personnel. CONCLUSIONS: It was demonstrated that TSST-1 producing MRSA became epidemic in the NICU as a result of the spread of a single clone.

Molecular Epidemiologic Surveillance of TSST-1 Strains Among Pathogenic Staphylococcus aureus / 감염

BACKGROUND: Toxic shock syndrome toxin 1 (TSST-1) is an important pathogenic factor in toxic shock syndrome, and its structural gene, tst has been cloned and sequenced, many of its biological and physicochemical properties have been determined, and immunostimulatory properties such as TNF production have been assigned to it. We investigated to know the proportion of strains possessing tst gene among pathogenic Strains of Staphylococcus aureus isolated from hospitalized patients and to elucidate the coexistence of mecA gene and tst gene. METHODS: S. aureus strains isolated in Asan Medical Center from December 1996 to June 1997 were incubated in brain-heart infusion media and harvested. Chromosomal DNA was prepared and polymerase chain reaction (PCR) was performed to detect mecA gene and tst gene in pathogenic S. aureus. RESULTS: A total of 126 strains were included. Among these, 11 strains (8.7%) were positive in PCR for tst gene. Ten out of these were mecA-positive strains and only one was mecA-negative. That is to say, among 60 strains of mecA-positive MRSA, 10 (16.7%) were tst-positive, and among 66 strains of mecA-negative MSSA, only one (1.5%) was tst-positive. CONCLUSION: Among S. aureus isolated from hospitalized patients, tst- possessing strains were 8.7%. TSST-1 gene was more prevalent in mecA-positive S. aureus than in mecA-negative S. aureus.