An improved method for the serotyping of free coagulase from Staphylococcus aureus

Development of rapid coagulase serotyping method by PCR and microplate hybridization

We developed a novel PCR-based method for coagulase serotyping. Coagulase gene amplicons biotinylated by PCR were identified by microplate hybridization (MPH) using serotype-specific probes. The conventional serotyping method, which is strongly dependent on coagulase activity, may sometimes give a mistaken determination of the serotype, especially in cases where there is high coagulase activity. In contrast, the results of PCR-MPH are not affected by coagulase activity. Furthermore, once the isolated colonies are obtained, it only takes 3 h to perform PCR-MPH, and the interpretation of the results is entirely objective. We compared PCR-MPH with the conventional method for 90 strains of coagulase-producing Staphylococcus aureus. The same results were found for both the PCR-MPH and conventional methods, and thus, our results indicate that PCR-MPH is a rapid, objective, and reliable method for coagulase serotyping.

Initial stage of hospital contamination with methicillin-resistant Staphylococcus aureus in Lao People's Democratic Republic

Monitoring drug-resistant Staphylococcus aureus has been carried out in Lao People's Democratic Republic (Lao PDR) since 1993. No methicillin-resistant S. aureus (MRSA) strains were detected until 2001 when two isolates were found: 01LP40, which was coagulase type IV, enterotoxin non-productive, and SCCmec (staphylococcal chromosome cassette mec) type III; and 01LP63 from a different hospital, which was coagulase type II, enterotoxin productive, and the SCCmec belonged to a new type. In 2002 four MRSA isolates similar to the latter were detected, 02LP211, 02LP214, 02LP217 from the same hospital as 01LP63, and 02LP100 from a third hospital. This appears to be the initial stage of a MRSA epidemic in Lao PDR. Careful monitoring and intensive monitoring and precautions are recommended.

Staphylococcus aureus isolated from hospital staff: a comparative study of Laos and Japan

Staphylococcus aureus isolated from hospital staff (nurses and doctors) in Laos were characterized for future reference and for comparison with organisms found in Okinawa, Japan. No methicillin-resistant S. aureus (MRSA), among 38 isolates examined, was found in Laos, but 16 of 36 Japanese isolates (44%) were identified as MRSA. The minimum inhibitory concentrations (MICs) of ampicillin and tetracycline against Lao isolates were definitely higher than those against Japanese isolates. The MIC(80) of tetracycline was 50 microg/ml and 0.4 microg/ml in Lao and Japanese isolates, respectively. There was no marked difference in the production of enterotoxin by S. aureus strains in the two countries. Toxic shock syndrome toxin-1 was produced by only 1 of 38 Lao isolates but by 5 of 36 Japanese isolates. Coagulase types varied greatly, but about 50% of the isolates in both countries produced untypable coagulase. Since the interaction of Laotians with foreigners has increased rapidly in recent years, the careful monitoring of drug-resistant pathogens is required.

A long-term survey of methicillin-resistant Staphylococcus aureus in the oral cavity of children

Methicillin-resistant Staphylococcus aureus (MRSA), an indigenous bacteria in healthy people, often causes nosocomial infections. If the host human becomes compromised, MRSA can cause a serious infection. The long-term colonization of MRSA increases this risk. The purpose of this study was to demonstrate the incidence of S. aureus and MRSA colonization in the oral cavities of healthy children, and to examine the stability of identical strains of MRSA over a long-term period. Fourteen children were examined in two stages (first stage: 1987-88, second stage: 1992-93). Five of the 14 children were negative for S. aureus in both stages, seven children were positive in both stages and two children were positive in only the second stage. The children who were colonized with S. aureus in the first stage always harbored the bacteria in the second stage. Of the seven children that were positive for S. aureus in both stages, three persisted in carrying MRSA. We compared two MRSA strains isolated from the same children in both stages by coagulase typing, antibiogram typing and DNA fingerprinting. In two children, the strains showed the same coagulase types, similar antibiograms and similar DNA fragment profiles. These data strongly suggest that identical strains of MRSA persisted in the oral cavities for more than five years, and that the oral cavity can serve as a reservoir for MRSA with the potential to cause nosocomial infections.