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Analysis of methicillin-resistant Staphylococcus aureus by IS1181 profiling
C Symms1, B Cookson, J Stanley
1Molecular Biology Unit, Virus Reference Division, Central Public Health Laboratory, London.
Abstract:
Variation in the genomic location and copy number of the insertion element IS1181 in methicillin-resistant Staphylococcus aureus (MRSA) was investigated. Sixty-three isolates representing the Jevons type strain (NCTC 10442), phage-propagating strains, and epidemic strains were examined. A PCR amplicon of the insertion element was used to probe genomic restriction endonuclease digests. HindIII genomic digests gave 25 distinct IS1181 patterns, while EcoRI digests gave 20 patterns. EMRSA-01, -02, -04, -06, -07, -09, -10, -11, -13 and -14 contained the element but could not be subtyped by profiling it. EMRSA-16 did not contain IS1181, consistent with a unique evolutionary origin for this major UK epidemic strain. Marked heterogeneity was observed among isolates of EMRSA-03. Each EMRSA-03 strain examined gave a unique pattern, thereby allowing subtyping of an important epidemic phage type for the purposes of hospital cross-infection control.
Insights
Genomic analysis of methicillin-resistant Staphylococcus aureus (MRSA) revealed significant variation in the IS1181 insertion element
Area of Science:
- Microbiology
- Genomics
- Molecular Biology
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) is a significant public health concern.
- The insertion element IS1181 is found in some MRSA strains, but its genomic distribution and copy number are not well understood.
- Understanding IS1181 variation can provide insights into MRSA evolution and epidemiology.
Purpose of the Study:
- To investigate the genomic location and copy number of the IS1181 insertion element in various MRSA isolates.
- To determine if IS1181 profiling can be used for subtyping and epidemiological tracking of MRSA strains.
Main Methods:
- Sixty-three MRSA isolates were analyzed, including type strains, phage-propagating strains, and epidemic strains.
- Polymerase chain reaction (PCR) was used to amplify the IS1181 element.
- Genomic restriction endonuclease digests (HindIII and EcoRI) were probed with the IS1181 amplicon to analyze patterns.
Main Results:
- Significant variation in IS1181 genomic location and copy number was observed among MRSA isolates.
- HindIII digests yielded 25 distinct IS1181 patterns, and EcoRI digests yielded 20 patterns.
- EMRSA-16 lacked IS1181, suggesting a distinct evolutionary path. EMRSA-03 isolates showed marked heterogeneity, with each strain exhibiting a unique IS1181 pattern.
Conclusions:
- IS1181 profiling demonstrates considerable genomic heterogeneity within MRSA.
- The absence of IS1181 in EMRSA-16 supports its unique evolutionary origin.
- IS1181 subtyping of EMRSA-03 is a valuable tool for hospital cross-infection control and epidemiological surveillance.