286. Associations between Length of Incarceration in Maximum-Security Prisons and Staphylococcus aureus Isolate Distribution
Session: Poster Abstract Session: HAI: MSSA, MRSA, and other Gram-Positives
Thursday, October 27, 2016
Room: Poster Hall

Background: Staphylococcus aureus (SA) colonization prevalence in prisons exceeds that in the general population; however, little is known about SA transmission during non-outbreak periods. High prevalence may be due to facility-level factors that promote the amplification and spread of SA. To address this, we assessed associations between inmate length of stay (LOS) and the distribution of SA carriage isolates in prisons.

Methods: Between 2009 and 2013, nares and oropharyngeal samples were collected from men and women at two prisons in New York State upon entry, release, and/or while incarcerated. LOS was based on transfer date into the facility. SA isolates were characterized by spa typing and Based Upon Repeat Pattern analysis for clonal relatedness. Associations between increasing LOS and colonizing spa clonal complexes (spa-CC) were explored using multivariable logistic regression to account for methicillin susceptibility and facility and comparing CC008 (USA300/USA300-related strains) with all other spa-CCs. For participants who were interviewed twice, McNemar’s test was used to identify differences in the proportions of predominant clones.

Results: The final sample size was 2,769; 60% and 49% of male inmates and 51% and 41% of female inmates were SA colonized at entry and release, respectively. The median LOS was 3 and 5 months for men and women, respectively. In all, 1,720 isolates were evaluated; the most common spa-CC was CC008 (24%). Increased LOS was associated with greater representation by CC008 (odds ratio=1.95; p=0.04) for nasal, methicillin-susceptible isolates. For the 212 inmates who were interviewed twice, a median of 7 months elapsed between interviews. Overall, 50% and 46% were colonized at the first and second interviews, respectively. For participants with nasal colonization at both interviews (n=71) the relative frequency of CC008 increased at the second interview (Figure 1; p=0.03).

Conclusion: Although the prevalence of SA colonization was lower among released inmates, increased LOS was associated with a greater relative abundance of CC008. While this suggests that SA transmission occurred the high prevalence of SA in prisons is likely maintained by the constant introduction of isolates due to recidivism and transfers.




Carolyn Herzig, PhD, MS, Department of Epidemiology, Columbia University Mailman School of Public Health, New York, NY, Elaine Larson, RN, PhD, School of Nursing, Columbia University Medical Center, New York, NY and Franklin Lowy, MD, FIDSA, College of Physicians and Surgeons, Division of Infectiou Diseases, Columbia University, New York, NY


C. Herzig, None

E. Larson, None

F. Lowy, None

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