臺灣methicillin抗藥性金黃色葡萄球菌抗藥性基因之分型研究(1/2)
Date Issued
2004
Date
2004
Author(s)
張上淳
DOI
922314B002160
Abstract
The first clinical isolate of methicillin-resistant Staphylococcus aureus (MRSA) in
Taiwan was found in 1981. During the past decades, the nosocomial MRSA infection rate
increased rapidly and MRSA became one of the most important nosocomial pathogens in
Taiwan. Given the fact that only few antibiotics can be used to treat MRSA infections, MRSA
had become a major problem for current medicine. Thus the mechanism of methicillin
resistance carried by MRSA is also an important clinical issue.
In the previous studies on methicillin resistance of MRSA, it has been found that the
methicillin resistance of MRSA is carried by a chromosome gene, mecA gene. The mecA gene
and its regulator genes, mecI and mecR1, consists of the mecA gene complex. The mecA gene
complex is widely distributed among S. aureus species as well as among other staphylococcal
species collectively called coagulase-negative staphylococci. Therefore, it has been
speculated that mec may be freely transmissible among staphylococcal species. In the 1980s,
direct chromosome analysis of MRSA strains revealed that a substantial length of the
chromosomal DNA segment (greater than 30 kb) carrying mec has no allelic equivalence in
methicillin-susceptible S. aureus (MSSA) strains. According to the studies of Hiramatsu et al,
the “mec DNA” is now formally renamed as “SCCmec (Staphylococcal cassette chromosome
mec) element” and the SCCmec element is almost universally found in all MRSA isolates.
The most important components in SCCmec element are the ccr (cassette chromosome
recombinase) genes, ccrA and ccrB, and mecA gene complex. The mecA gene complex can be
classified into four types, type A, B, C, D. The ccr genes can be classified into to three types.
The function of ccr genes is to precisely excise and insert the SCCmec element in way of both
site and orientation specifically. Based on the structures and combinations of ccr genes and
mecA gene complex, the SCCmec gene element in MRSA can be classified into four types
In Taiwan, previous studies rarely deal with the genetics of methicillin resistance of
MRSA. Our study will focus on the genetic classification of mecA gene complex and ccr
complex of MRSA isolated in Taiwan. Despite further determining the types of SCCmec
element of MRSA in Taiwan to compare with those in other country and then clarify the its
phylogenic source, the mechanism of methicillin resistance of MRSA in Taiwan will be also
more illuminated at the same time.
Subjects
methicillin-resistant Staphylococcus aureus
MRSA
SCCmec element
Publisher
臺北市：國立臺灣大學醫學院內科
Type
report
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