Analysis of methicillin-resistant Staphylococcus aureus by IS1181 profiling

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.