Characteristics of the community-genotype sequence type 72 methicillin-resistant Staphylococcus aureus isolates that...

Area of Science:

• Microbiology
• Infectious Diseases
• Bacterial Pathogenesis

Background:

• Panton-Valentine leukocidin-negative methicillin-resistant Staphylococcus aureus (MRSA) clone ST72 is a significant community-associated pathogen in Korea.
• ST72 MRSA has increasingly been identified as a nosocomial pathogen in hospital settings.
• Understanding the factors contributing to ST72's transition from community to hospital environments is crucial.

Purpose of the Study:

• To investigate the bacterial properties of ST72 MRSA that facilitate its emergence as a nosocomial pathogen.
• To compare the characteristics of ST72 MRSA with predominant nosocomial MRSA clones ST5 and ST239 in Korea.

Main Methods:

• Comparative analysis of virulence and adhesion genes in ST72, ST5, and ST239 MRSA isolates.
• Assessment of agr group distribution and functionality (delta-hemolysin production) in the isolates.
• Evaluation of biofilm formation capacity.
• Determination of ST72 MRSA survival rates under hypotonic and desiccating conditions.

Main Results:

• ST72 isolates lacked several adhesion and virulence genes found in ST5 and ST239.
• A high percentage of ST72 isolates (70.1%) belonged to agr group I, with functional agr systems, unlike the agr-dysfunctional ST5 and ST239 isolates.
• ST72 MRSA showed no enhanced biofilm formation but demonstrated significant persistence under hypotonic (72.3% survival) and desiccating (33.9% survival) conditions.
• ST72 MRSA exhibited low overall virulence.

Conclusions:

• The functional agr system in ST72 MRSA may promote its dissemination within hospital environments.
• Tolerance to environmental stressors like hypotonicity and desiccation likely contributes to the survival and spread of community-associated MRSA clones in healthcare facilities.
• These findings highlight the adaptability of ST72 MRSA as a nosocomial threat.