Distribution of capsular and surface polysaccharide serotypes of Staphylococcus aureus

Area of Science:

• Microbiology
• Vaccinology
• Epidemiology

Background:

• Staphylococcus aureus, including methicillin-resistant strains (MRSA), causes severe infections, necessitating effective prevention strategies.
• The emergence of MRSA in community settings highlights the need for broader vaccine coverage.
• Understanding circulating serotypes is crucial for developing effective S. aureus vaccines.

Purpose of the Study:

• To determine the serotype distribution of German Staphylococcus aureus isolates, including MRSA and methicillin-susceptible S. aureus (MSSA).
• To evaluate the potential of a polysaccharide conjugate vaccine by assessing serotype coverage.
• To identify key serotypes for inclusion in a next-generation S. aureus vaccine.

Main Methods:

• Serotyping of 714 German MSSA and MRSA strains using slide agglutination with specific antibodies (anti-T5-DT, anti-T8-DT, anti-336-rEPA).
• Confirmation of serotypes via immunodiffusion using lysostaphin-digested cell lysates.
• Analysis of serotype prevalence across different healthcare settings and patient outcomes.

Main Results:

• Among MRSA strains (representing >90% of spa types), serotype 5 was most common (45.3%), followed by type 8 (41.9%) and type 336 (12.8%).
• Serotype 336 was the second most prevalent MRSA serotype across diverse German laboratories.
• Type 8 strains were more common in nasal isolates from patients who did not develop S. aureus bacteremia.

Conclusions:

• The addition of serotype 336 to a polysaccharide conjugate vaccine could substantially increase coverage against circulating S. aureus strains in Germany.
• A vaccine incorporating types 5, 8, and 336 would likely cover the vast majority of MSSA and MRSA isolates.
• This research provides critical data for the development of a broadly protective S. aureus vaccine.