Restriction fragment length polymorphism (RFLP) patterns and sequence analysis of high-level mupirocin-resistant...

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• High-level mupirocin resistance (MuH) in staphylococci is primarily mediated by the acquisition of the mupA gene, often located on plasmids.
• Understanding the genetic basis and location of the mupA gene is crucial for tracking and managing antibiotic resistance.

Purpose of the Study:

• To investigate the heterogeneous location and sequence variations of the mupA gene in high-level mupirocin-resistant staphylococci.
• To analyze the genetic structure of the mupA-carrying cassette, including the transfer gene complex (trs) and insertion sequence (IS257-like).

Main Methods:

• Restriction fragment length polymorphism (RFLP) analysis of the mupA gene in 14 MuH staphylococci isolates.
• DNA sequencing of the trsLM-IS257-like-mupA cassette to identify variations.

Main Results:

• Four distinct RFLP patterns were observed, attributed to sequence deletions between the mupA gene and the trsLM region.
• Four different sequence types of the trsLM-IS257-like-mupA cassette were identified.
• The IS257-like sequence showed variations (two base substitutions, one deletion) compared to the reference IS257 sequence.

Conclusions:

• Sequence deletions adjacent to the IS257-like sequence within the cassette are responsible for the heterogeneous location of the mupA gene.
• The IS257-like sequence is consistently present in all studied MuH staphylococci, suggesting its role in the cassette structure and gene location.