MRSA colonization and the nasal microbiome in adults at high risk of colonization and infection

Area of Science:

• Microbiology
• Medical Science
• Infectious Diseases

Background:

• Hospital inpatients are at risk for persistent colonization with methicillin-resistant Staphylococcus aureus (MRSA).
• The nasal microbiome plays a role in susceptibility to MRSA colonization.
• Understanding the nasal microbial communities associated with MRSA colonization is crucial for infection control.

Purpose of the Study:

• To define the nasal microbiome of hospital inpatients persistently colonized with MRSA.
• To compare the nasal microbiotas of MRSA-colonized individuals with matched non-colonized controls.

Main Methods:

• Analysis of nasal microbiotas from 26 persistently MRSA-colonized subjects and 26 matched controls using 16S rRNA gene sequencing.
• Statistical analysis including stratified logistic regression and canonical discriminant analysis.
• In vitro coculture experiments to assess bacterial competition between MRSA and other nasal organisms.

Main Results:

• A negative association was observed between MRSA colonization and colonization with Streptococcus spp., specifically Streptococcus mitis and Lactobacillus gasseri.
• In vitro experiments demonstrated direct competition between S. mitis and MRSA, which was mediated by catalase.
• Persistently MRSA-colonized subjects exhibited lower nasal microbial diversity compared to non-colonized controls.

Conclusions:

• Bacterial competition within the nasal niche is a protective factor against MRSA colonization in high-risk inpatient settings.
• Specific bacterial species like S. mitis may play a significant role in preventing MRSA colonization through competitive interactions.