A study on postoperative enteritis caused by methicillin-resistant Staphylococcus aureus

We investigated the production of staphylococcal enterotoxin (SE) with respect to coagulase types by methicillin-resistant Staphylococcus aureus (MRSA). A total of 138 strains of MRSA, which were isolated from clinical materials in the surgical ward between 1983 and 1990, were studied. Coagulase type IV strains produced SE A only, whereas coagulase type II strains were classified into four groups by SE production: SE B producing strains (32.7%), SE C producing strains (29.8%), SE B and C coproducing strains (12.5%), and SE A and C coproducing strains (25.0%). Almost all of the organisms (nine of ten) which were isolated from the feces of patients with MRSA enteritis were SE A and C coproducing strains. The coincidence in time of the prevalence of MRSA enteritis and the isolation SE A and C coproducing strains also demonstrated that these strains caused MRSA enteritis. Although SE C producing strains and SE A and C coproducing strains were simultaneously prevalent in 1990, the former tended to be sensitive while the latter tended to be resistant to minocycline. Considering the variety of antibiotic sensitivity in coagulase type II strains, it is thus considered to be of critical importance for epidemiologic purposes to further characterize isolates by SE typing.

Susceptibility of methicillin-resistant Staphylococcus aureus clinical isolates to various antimicrobial agents. II. Isolation of arbekacin-resistant strain

Resistance patterns against 24 antimicrobial agents were examined for 50 strains of methicillin-resistant Staphylococcus aureus (MRSA) isolated at Hiroshima University Hospital during the period October 1990 and July 1991. Overall resistance (the percentage of highly and moderately resistant strains) to the antimicrobial agents is summarized as follows: methicillin 100%, flomoxef 100% (beta-lactams); kanamycin 94%, tobramycin 94%, amikacin 100%, isepamicin 94%, gentamicin 80%, dibekacin 94%, arbekacin 2% (basic oligosaccharide group/aminocyclitols); ofloxacin 96%, temafloxacin 96%, levofloxacin 96% (fluoroquinolones); erythromycin 98%, clarithromycin 98%, josamycin 30% (macrolides); vancomycin 0% (glycopeptide); tetracycline 94%, minocycline 94% (tetracyclines); fosfomycin 100%; mikamycin B 30%, nosiheptide 0% (peptide); rifampicin 2% (ansamycin); streptomycin 2% (basic oligosaccharide group); chloramphenicol 2%. Arbekacin resistance was observed in one case: the cross resistance was complete among the aminocyclitol antibiotics tested in this study and streptomycin, probably due to the ribosomal alteration.

Toxin involvement in methicillin-resistant Staphylococcus aureus enteritis in gastroenterological surgery

The authors investigated the production of toxic shock syndrome toxin-1 (TSST-1) and staphylococcal enterotoxins (SE) by Methicillin-resistant Staphylococcus aureus (MRSA) isolates to clarify the pathogenesis of postoperative MRSA enteritis in patients undergoing gastroenterological surgery. Regarding the percentage of TSST-1 producing strains, there was a significant difference between type II MRSA strains (68.8%) and type IV MRSA strains (4.2%). Among type II strains, all those producing staphylococcal entorotoxin (SE) type C (SEC) also produced TSST-1, although other strains that produced SEB without TSST-1 were commonly isolated. Strains producing SEA were potent producers of SE which was considered to be responsible for enteritis. Therefore, we hypothesized that the strains which produced both SEA and SEC tended to cause enteritis associated with TSS-like symptoms owing to the high titer of these toxins.