Survey of methicillin-resistant Staphylococcus aureus strains from two hospitals in El Paso, Texas

Area of Science:

• Microbiology
• Epidemiology
• Infectious Diseases

Background:

• Methicillin-resistant Staphylococcus aureus (MRSA) is a significant cause of healthcare-associated infections.
• Understanding the genetic diversity and clonal spread of MRSA is crucial for infection control.
• Previous data on MRSA epidemiology in El Paso, Texas, was limited.

Purpose of the Study:

• To characterize the molecular epidemiology of MRSA isolates from two medical centers in El Paso, Texas.
• To identify the prevalent MRSA pulsed-field gel electrophoresis (PFGE) types and their associated sequence types (STs) and staphylococcal chromosomal cassette mec (SCCmec) types.
• To assess the presence of epidemic MRSA clones in the El Paso region.

Main Methods:

• MRSA isolates were collected from two medical centers in El Paso, Texas.
• Pulsed-field gel electrophoresis (PFGE) was performed to determine genetic relatedness.
• Multilocus sequence typing (MLST) and SCCmec typing were conducted to characterize the isolates.
• Data analysis was performed to identify clonal types and their prevalence.

Main Results:

• A total of 76 MRSA strains were analyzed.
• Seventy-one percent of the isolates belonged to three similar PFGE types.
• Six distinct PFGE types were identified, corresponding to ST5-MRSA-II, ST36-MRSA-II, ST8 (untypeable SCCmec), and a novel clonal cluster 8 strain, ST507-MRSA-IV.
• The findings indicate the presence of multiple antibiotic-resistant epidemic MRSA clones in El Paso.

Conclusions:

• This study highlights the genetic diversity and clonal nature of MRSA in El Paso, Texas.
• The predominance of specific MRSA clones suggests potential for widespread transmission.
• Effective infection control strategies are necessary to manage the spread of these epidemic MRSA strains.