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Phage typing of methicillin-resistant Staphylococcus aureus
1Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Kuala Lumpur.
Abstract:
448 isolates of methicillin-resistant Staphylococcus aureus (MRSA) from clinical specimens of patients from the University Hospital, Kuala Lumpur, were phage-typed. These included 35 strains causing two separate outbreaks of infection, one in surgical Ward 6B and another in the Special Care Nursery (SCN). Antibiograms of these outbreak strains in Ward 6B and SCN were entirely different. Phage-typing revealed that 72% of the MRSA isolates were typable. They were typed entirely by Group III phages, the majority (76%) of which were phage type 85. There was only one isolate in SCN which was typed by Group I (phage 80) and Group III phages. None were typed by phages 94, 95, 96 and Group II phages. 14.6% of the typable isolates gave the long pattern reaction of the phage 6/47/54/75/77/83A/84/85 complex. The majority of the outbreak strains in Ward 6B were of phage type 85, whereas those in the SCN were all of the 6/47/54/75/77/83A/84 phage pattern with the exception of one isolate which was also typed by phage 80, a Group I phage.
Insights
Methicillin-resistant Staphylococcus aureus (MRSA) outbreaks in a hospital were analyzed using phage typing. Most MRSA strains belonged to Group III phages, with distinct patterns observed between different hospital wards.
Area of Science:
- Microbiology
- Infectious Diseases
- Epidemiology
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) is a significant cause of hospital-acquired infections.
- Understanding MRSA epidemiology through methods like phage typing is crucial for infection control.
Purpose of the Study:
- To characterize MRSA isolates from clinical specimens at University Hospital, Kuala Lumpur.
- To investigate MRSA strains involved in outbreaks in surgical Ward 6B and the Special Care Nursery (SCN).
- To differentiate outbreak strains using phage typing and antibiograms.
Main Methods:
- Phage typing was performed on 448 MRSA isolates from clinical specimens.
- Specific attention was given to 35 strains from two distinct outbreaks in Ward 6B and SCN.
- Antibiograms were compared between outbreak strains.
Main Results:
- 72% of MRSA isolates were typable, predominantly by Group III phages (76% being phage type 85).
- Outbreak strains in Ward 6B were mainly phage type 85.
- SCN outbreak strains exhibited a different pattern (6/47/54/75/77/83A/84), with one isolate also typed by Group I phage 80.
Conclusions:
- Phage typing effectively differentiated MRSA strains involved in distinct hospital outbreaks.
- The study highlights the etiological diversity of MRSA in different clinical settings within a single hospital.
- Group III phages, particularly type 85, were predominant among the studied MRSA isolates.