Phage-typing of Staphylococcus aureus from cases of bacteraemia

Area of Science:

• Medical Microbiology
• Infectious Diseases
• Epidemiology

Background:

• Staphylococcus aureus is a significant cause of bacteremia.
• Understanding the phage types of S. aureus is crucial for tracking infection sources and spread.
• Differentiating between sporadic and outbreak-associated strains aids in infection control.

Purpose of the Study:

• To characterize the phage types of Staphylococcus aureus isolates from bacteremia cases.
• To determine if specific phage types are associated with sporadic infections versus hospital outbreaks.

Main Methods:

• Phage typing was performed on 98 Staphylococcus aureus isolates from 16 hospitals.
• Isolates were categorized based on their association with sporadic infections or hospital outbreaks.
• Prevalence of different phage types within each category was analyzed.

Main Results:

• Group I strains, including types 29, 52, or 29/52, were frequent (39.2%) in sporadic bacteremia cases.
• Type 94/96 strains were also common (14.2%) in sporadic infections.
• Hospital outbreaks were predominantly associated with mixed Group I and III strains (73.6%), often multiply-resistant, and non-typable strains (21.4%).

Conclusions:

• Phage typing effectively distinguishes Staphylococcus aureus strains involved in sporadic bacteremia from those causing hospital outbreaks.
• Specific phage types, like Group I, are more common in sporadic infections, whereas multiply-resistant strains are key in outbreaks.
• These findings support the use of phage typing for epidemiological surveillance and infection control of S. aureus bacteremia.