225520 Correlation of antibiotic exposure with development of extreme drug resistant Acinetobacter baumannii

Monday, November 8, 2010 : 1:05 PM - 1:20 PM

Haritha Pallam, Master of Public Health , Division of Infectious Diseases, University Of Louisville, Louisville, KY
Karen McCurley, Infection Preventionist , Infection control, Kindred Hospital Louisville, Louisville, KY
Julie Harting, PGY2 Infectious Disease Resident , Dept. of Clinical and Administrative Sciences, Sullivan University College of Pharmacy, Louisville, KY
Juanita Clay, Director of Quality Management , Kindred Health Care, Kindred Hospital Louisville, Louisville, KY
Michelle Hall, MIcrobiologist , Microbiology, Kindred Hospital Louisville, Louisville, KY
Susan B. Muldoon, PhD , Department of Epidemiology and Population Health, University of Louisville School of Public Health and Information Sciences, Louisville, KY
Timothy Weimken, MPH CIC , Division of Infectious Diseases, University Of Louisville, Louisville, KY
Paula Peyrani, House staff , Division of Infectious Diseases, University Of Louisville, Louisville, KY
Julio Ramirez, Professor of Medicine and Chief of the Division of Infectious Diseases , Division of Infectious Diseases, University Of Louisville, Louisville, KY
Introduction: Prior exposure to antibiotic therapy is a well-defined risk factor for development of multidrug resistant (MDR) and extreme drug resistant (XDR) organisms. This association is primarily due to the disruption of the normal flora by antibiotics (collateral damage). We recently developed an antibiotic exposure score, ranging from 1-5, to estimate the level of collateral damage. The objective of this study was to define if an association exists between increasing Antibiotic Exposure score and development of XDR-Acinetobacter baumannii.

Materials and Methods: We reviewed medical records of patients infected with MDR- and XDR-Acinetobacter to define antibiotics used during the prior 30 days. The population exposure (PE) score was calculated by adding all antibiotic exposure scores for all patients. Median PE scores were also calculated for MDR and XDR-Acinetobacter separately. The Mann-Whitney U test was used to compare the PE scores for MDR and XDR-Acinetobacter populations. Differences with P-values of ≤0.05 were considered statistically significant.

Results: A total of 46 patients were reviewed. The PE score for the full population was 410. The median PE score for those with MDR-Acinetobacter was 9.0 (Inter quartile Range: 6.0 to 14). The median PE score for those with XDR-Acinetobacter was 9.1 (Inter quartile Range: 4 to 13.5). There was not a significant difference between PE scores (p=0.96).

Conclusions: Antibiotic collateral damage, as measured by PE score, was not able to predict the presence of MDR/XDR-Acinetobacter. This data suggests that factors beyond antibiotic exposure are important in the evolution of Acinetobacter from MDR to XDR.

Learning Areas:
Public health biology

Learning Objectives:
Explain the importance of studying collateral damage of host normal flora (caused by prolonged antibiotic exposure) leading to increased susceptibility towards drug resistant pathogens. Discuss quantitative methods to identify the relationship between increasing antibiotic exposure and development of Multi or Extreme drug resistant infections.

Presenting author's disclosure statement:

Qualified on the content I am responsible for because: I directed the data collection and analysis
Any relevant financial relationships? No

I agree to comply with the American Public Health Association Conflict of Interest and Commercial Support Guidelines, and to disclose to the participants any off-label or experimental uses of a commercial product or service discussed in my presentation.