Staphylococcus aureus remains an important human pathogen, causing both benign as well as invasive infections. Colonization of mucosal sites, particularly the anterior nares, is associated with subsequent infection, and persistently colonized individuals, individuals from whom S. aureus in consistently isolated, are at elevated risk of infection and transmission. Obese individuals have been shown to be at elevated risk of colonization with S. aureus, however, the influence of obesity on persistent colonization has yet to be established.
A series of cross-sectional data from two New York State prisons collected at inmate entry, during their sentence and prior to release into the community were used. Structured interviews and medical charts were used to collect demographic, behavioral and medical data. Self-reported height and weight were used to calculate BMI categories. Anterior nares and oropharyngeal cultures were collected from each participant at the time of each interview to determine colonization status. Confirmed isolates were characterized by spa typing and compared using Ridom Staph Type software. Log-binomial regression was then used to assess the influence of obesity on persistent S. aureus colonization and Simpson’s Index of Diversity (SID) and correspondence analysis (CA) were used to determine differences in strain diversity in persistent carriers as compared to intermittent.
Approximately 27% of the 274 individuals included in the analysis were persistent carriers at the species level and 17% were persistent carriers at the strain level. Obesity was independently associated with species persistence (Prevalence Ratio (PR)=1.54 95%CI 1.01, 2.38) but not strain persistence (PR=1.15 95%CI 0.60, 2.05). Diversity of S. aureus strains as assessed by SID did not differ among persistent (SID=95.3, 95%CI 93.5, 97.0) as compared to intermittent carriers (SID= 95.6%, 95%CI 93.3, 97.8), however, CA demonstrated differences in strain composition among persistent exclusive nasal carriers as compared to exclusive oropharyngeal and intermittent carriers.
Obese inmates were at elevated risk of species level persistent S. aureus carriage, and compositional differences were observed between persistent carriers as compared to intermittent carriers when CA was implemented.
E. Larson, None