Methicillin-resistant Staphylococcus aureus typing methods: which should be the international standard?

Molecular epidemiology and antimicrobial susceptibility of methicillin-resistant Staphylococcus aureus in Taiwan

Methicillin-resistant Staphylococcus aureus (MRSA) has become an important nosocomial pathogen and has increased frequency in the past 20 years. It is highly transmissible between wards, hospitals, and cities. In most major hospitals in Taiwan, MRSA accounts for more than 60% of the S. aureus isolates. Whether there is a predominant strain, which is spread over the whole of Taiwan has not yet been studied. We collected 208 sequential clinical isolates of MRSA from 22 hospitals: seven in northern Taiwan, seven in western Taiwan, five in southern Taiwan, and three in eastern Taiwan during a three-month period in 1998. Using pulsed-field gel electrophoresis, 112 MRSA isolates were shown to belong to one major type,--type C, and this type was shown to have spread widely across all of Taiwan. Ninety-six isolates belonged to 20 other minor types. Most MRSA isolates of this major type were multi-drug resistant and only susceptible to vancomycin and rifampin. We concluded that the high prevalence of MRSA in Taiwan was partly due to the spreading of a predominant strain and most of them were multi-drug resistant. This might imply that more effort should be made to control the spread of MRSA in Taiwan.

Molecular typing of strains of staphylococcus aureus isolated from bone and joint lesions in lame broilers by random amplification of polymorphic DNA

A study was conducted to investigate the relationship between the presence of localized bacterial infection and lameness in broiler fowl (Gallus gallus domesticus). Isolation of bacteria from the proximal femur, proximal tibia, and tibiotarsus from broilers with lameness revealed a probable association between lameness and the presence of Staphlylococcus aureus. Other potential pathogens, including Escherichia coli and DNase-negative staphylococci, were also isolated from sound and lame birds, and their association with pathologies causing lameness was less well defined. After trials with a set of twenty 10-base oligonucleotide primers, a pair of primers giving optimal performance was selected. The S. aureus isolates were typed by random amplification of polymorphic DNA (RAPD) by using the pair of 10-mer primers, and groupings were defined by banding patterns after agarose gel electrophoresis. The putative RAPD groupings may provide a basis for epidemiological studies of S. aureus in broiler production systems.