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Investigation of nosocomial infection caused by arbekacin-resistant, methicillin-resistant Staphylococcus aureus
Y Obayashi1, J Fujita, S Ichiyama
1First Department of Internal Medicine, Kagawa Medical University, Japan.
Abstract:
An outbreak of coagulase VII-producing, arbekacin (ABK)-resistant, methicillin-resistant Staphylococcus aureus (MRSA) occurred between September 1994 and December 1995, involving five different wards. Twenty-one patients developed skin, wound, drainage, or respiratory tract colonization with coagulase VII-producing, (ABK)-resistant MRSA. Phenotypic characteristics (production of enterotoxin and TSST-1, antimicrobial susceptibility) and molecular-typing procedure (plasmid DNA profile, pulsed-field gel electrophoresis [PFGE] and arbitrarily primed polymerase chain reaction [AP-PCR] of chromosomal DNA) in isolated strains were compared. Plasmid analysis identified four different profiles and 19 of 22 strains recovered had identical patterns. PFGE of chromosomal DNA identified three different subtypes and 18 (81.8%) isolates shared the same subtype. AP-PCR also demonstrated that most strains had the same phenotypic characteristics. Although traditional epidemiological methods; for example, coagulase typing, plays a central role in hospital infection control, combination of plasmid DNA profile, AP-PCR, and PFGE may prove to be a particularly informative means of tracking the nosocomial spread of MRSA.
Insights
An outbreak of arbekacin-resistant, methicillin-resistant Staphylococcus aureus (MRSA) was tracked using molecular typing. Combining plasmid DNA profiling, AP-PCR, and PFGE effectively monitored the hospital-acquired MRSA spread.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Epidemiology
Background:
- An outbreak of coagulase VII-producing, arbekacin (ABK)-resistant, methicillin-resistant Staphylococcus aureus (MRSA) occurred between September 1994 and December 1995.
- Twenty-one patients across five wards were colonized with this resistant MRSA strain.
Purpose of the Study:
- To compare phenotypic characteristics and molecular typing methods for tracking MRSA.
- To evaluate the effectiveness of different molecular techniques in identifying MRSA strains during an outbreak.
Main Methods:
- Phenotypic characterization including enterotoxin production, TSST-1 production, and antimicrobial susceptibility testing.
- Molecular typing using plasmid DNA profiling, pulsed-field gel electrophoresis (PFGE) of chromosomal DNA, and arbitrarily primed polymerase chain reaction (AP-PCR) of chromosomal DNA.
- Comparison of results from traditional epidemiological methods (coagulase typing) with molecular methods.
Main Results:
- Plasmid analysis revealed four distinct profiles, with 19 of 22 strains showing identical patterns.
- PFGE identified three subtypes, and 18 (81.8%) isolates shared the same subtype.
- AP-PCR confirmed that most strains possessed similar phenotypic characteristics.
Conclusions:
- While coagulase typing is important for infection control, molecular methods offer enhanced discriminatory power.
- The combination of plasmid DNA profiling, AP-PCR, and PFGE is highly informative for tracking the nosocomial spread of MRSA.
- These advanced techniques aid in understanding and controlling outbreaks of antibiotic-resistant bacteria in healthcare settings.