Differences between the virulence of community-acquired and hospital drug-resistant bacterial strains

Is the virulence of community-acquired and hospital drug-resistant bacterial strains (eg, methicillin-resistant Staphylococcus aureus [MRSA]) the same? Are drug-resistant strain infections limited to patients with risk factors (eg, immunosuppression) or can they also affect healthy persons with no risk factors?

Mark Loeb: In terms of strains, if we take MRSA, for example, there is a community MRSA strain and there is a hospital strain. Certainly, there are different pathogenic features of that and clinically it manifests itself quite differently. For example, a community MRSA strain will cause boils and skin lesions and it can be severe, but it tends to be a little more susceptible to antibiotics like trimethoprim-sulfamethoxazole or clindamycin, whereas the hospital strains tend to be a little bit more resistant. It really depends on what kind of strains you are talking about.

In terms of populations, it also depends. Healthy people can easily acquire community MRSA, whereas often the hospital-acquired strain spreads in a hospital, and those people tend to be more debilitated and have comorbidities.