568. Health outcomes of nursing home residents colonized by antibiotic-resistant bacteria
Session: Poster Session: Hospital-acquired and Transplant Infections
Friday, October 30, 2009: 12:00 AM
Room: Poster Hall A
Background: Nursing home (NH) residents are commonly colonized with antibiotic-resistant bacteria (ARB) such as methicillin-resistant Staphylococcus aureus (MRSA) and fluoroquinolone-resistant gram-negative bacilli (FQRGNB). Studies have shown that infections caused by these bacteria are associated with excess morbidity and mortality, however, the health consequences of isolated colonization by these pathogens remains poorly understood.
Methods: Longitudinal data from NH residents participating in an ongoing study of antibiotic resistance in Wisconsin NHs were examined. All subjects had surveillance cultures of multiple anatomic sites each quarter to detect colonization by MRSA and FQRGNB. Information on hospitalizations and mortality were collected prospectively. The proportion of colonized and non-colonized subjects who were hospitalized during follow-up was compared using Poisson regression. Kaplan-Meier survival estimates of colonized and non-colonized subjects were compared using the log-rank test.
Results: Analysis of the data from 223 subjects residing in 4 NHs who had a baseline and at least one set of follow-up surveillance cultures showed that 71 subjects (32 %) were colonized at least once by MRSA and 101 (45%) by FQRGNB. To date, 14% of MRSA(+) subjects have been hospitalized at least once compared to 19% of MRSA(-) subjects (IRR = 1.01, P = 0.97) and 10% of MRSA(+) subjects and have died during follow-up compared to 9% of MRSA(-) subjects (IRR = 1.21, P = 0.70). 22% of FQRGNB(+) subjects have been hospitalized at least once compared to 14% of FQRGNB(-) subjects (IRR = 1.46, P = 0.15) while 13% of FQRGNB(+) subjects died during follow-up compared to 7% of FQRGNB(-) subjects (IRR = 2.1, P = 0.23).
Conclusion: A surprisingly high proportion of the NH residents participating in this study were colonized with ARB. While our preliminary analyses do not show statistically significant differences in health outcomes between ARB-colonized and non-colonized subjects, most of the subjects have been followed for a short period of time (~3 months).
Christopher Crnich, MD, MS, Section of Infectious Diseases, University of Wisconsin School of Medicine and Public Health, Madison, WI, Paul Drinka, MD, University of Wisconsin, Waupaca, WI, Dennis Maki, MD, FIDSA, University of Wisconsin Medical School, Madison, WI, David Zmmerman, PhD, University of Wisconsin, Madision, WI and  C. J. Crnich, None..
P. Drinka, None..
D. G. Maki, None..
D. R. Zmmerman, None.


C. Crnich, None

P. Drinka, None

D. Maki, None

D. Zmmerman, None