Methicillin-resistant Staphylococcus aureus sequence type 239-III, Ohio, USA, 2007-2009

Area of Science:

• Infectious Diseases
• Microbiology
• Epidemiology

Background:

• Methicillin-resistant Staphylococcus aureus (MRSA) exhibits significant molecular diversity.
• Common US MRSA strains include USA100 (ST5) and USA300 (ST8).
• MRSA ST239-III is frequently implicated in healthcare-associated outbreaks globally but rarely reported in the US.

Purpose of the Study:

• To investigate the prevalence and characteristics of MRSA ST239-III infections in US hospitals.
• To assess the clinical outcomes and risk factors associated with MRSA ST239-III infections.

Main Methods:

• Molecular typing was employed to identify MRSA strains among 1,286 patients.
• Data on infection source, patient history, and outcomes were collected and analyzed.

Main Results:

• MRSA ST239-III was identified in 78 (6%) of the patients studied.
• The majority of these infections (95%) were healthcare-associated.
• Invasive device use was reported in 65% of patients with MRSA ST239-III.
• The crude case-fatality rate was 22%.

Conclusions:

• The presence of MRSA ST239-III in US hospitals, even at a low prevalence, is significant due to its virulent nature.
• Healthcare-associated infections and invasive device use are key risk factors.
• Enhanced molecular surveillance is crucial for tracking and controlling this potentially dangerous MRSA strain.