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.

Correlation between Sau1 Restriction and Modification Complex Type and Coagulase Serotype or SCCmec Type of Staphylococcus aureus

Staphylococcus aureus coagulase serotype I to VIII isolated from clinical samples could be classified into two groups, methicillin-sensitive S. aurues (MSSA) and methicilln-resistant S. aurues (MRSA), by antibiotics susceptibility and existence of mecA which is a gene related with methicillin resistance. Coagulase serotype I, VI, and VIII were MSSA which showed different antimicrobial susceptibility. Coagluase serotype II-V and VII were MRSA in which mecA and SCCmec were detected. To analyze Sau1 restriction and modification (R-M) complex types by coagulase type and SCCmec type, sau1hsdR, sau1hsdM and sau1hsdS genes involved in Sau1 R-M complex were detected by PCR, we found five complex types such as M1, R2M2, R2M2, R2M2S1, and R2M2S2. Coagulase serotype I, VI, and VIII of MSSA were M1, R2M2 and R2M2, respectively. SCCmec type II and coagulase serotype II, SCCmec type III and coagulase serotype III, SCCmec type IV and coagulase serotype V, and SCCmec type IV and coagulase serotype IV, VII of MRSA were Sau1 R-M complex type R2M2S1, R2M2, R2M2, and R2M2S2, respectively. Taken together, correlation between Sau1 R-M complex types and coagulase or SCCmec types of S. aureus was found.

Correlation Between Staphylococcal Cassette Chromosome mec Type and Coagulase Serotype of Methicillin-Resistant Staphylococcus aureus

Staphylococcal cassette chromosome mec (SCCmec) type and coagulase serotype are important epidemiologic factors in methicillin-resistant Staphylococcus aureus (MRSA). To investigate correlation between SCCmec type and coagulase serotype of MRSA, we analyzed SCCmec types of MRSA strains isolated from clinical sources and compared the results to coagulase serotypes and antimicrobial susceptibility patterns. A total of 108 MRSA isolates were classified into four SCCmec types: II (55.6%), IV (21.3%) III (13.0%) and IIIA (8.3%), and five coagulase serotypes: II (54.6%), IV (21.3%), V (18.5%) and VII (2.8%). All of coagulase type II, IV and V strains belonged to SCCmec type II, III/IIIA and IV, respectively. SCCmec types II, III and IIIA were multidrug resistant, whereas SCCmec type IV strains were non-multidrug resistant except beta-lactams and erythromycin. The data provide that there is a significant correlation between SCCmec types and phenotypic characteristic of coagulase serotypes.