Virulence and antimicrobial resistance genes in human MRSA ST398 isolates in Austria

Area of Science:

• Microbiology
• Genetics
• Epidemiology

Background:

• Methicillin-resistant Staphylococcus aureus (MRSA) ST398 is a significant pathogen.
• Understanding its genetic makeup is crucial for public health.
• Austrian MRSA ST398 isolates were previously uncharacterized genetically.

Purpose of the Study:

• To determine the genetic basis of virulence and resistance in Austrian MRSA ST398 isolates.
• To analyze gene profiles over a defined period (2004-2008).
• To assess the relatedness of these isolates.

Main Methods:

• DNA microarray chip analysis was used to screen for virulence and resistance genes.
• SplitsTree analysis was employed to evaluate isolate relatedness.
• 41 human MRSA ST398 isolates collected between 2004 and 2008 were analyzed.

Main Results:

• A high degree of similarity in virulence gene profiles was observed in 70.7% of isolates.
• Genes for tetracycline resistance (tetM, tetK) were highly prevalent (all but one isolate).
• Resistance to erythromycin-lincosamide (ermC) was found in 29.9% of isolates.
• Panton-Valentine leukocidin and enterotoxin genes were notably absent.
• SplitsTree analysis indicated close genetic relatedness among 40 isolates.
• Minimal changes in gene patterns were detected over the study period.

Conclusions:

• Austrian MRSA ST398 isolates exhibit a conserved genetic background regarding virulence and resistance.
• Tetracycline and erythromycin-lincosamide resistance genes are common features.
• The genetic profile remained stable between 2004 and 2008, suggesting limited evolution within this timeframe.