518. Changing Incidence of Multidrug-Resistant Organisms Isolated in a Military Medical Center
Session: Poster Session: Hospital-acquired and Transplant Infections
Friday, October 30, 2009: 12:00 AM
Room: Poster Hall A
Background: Operation Iraqi and Enduring Freedom (OIF/OEF) combat casualties are at substantial risk to develop infections with multidrug-resistant (MDR) A. baumannii (AB) and P. aeruginosa (PA); increasingly the source of nosocomial infections in the military healthcare system. Characterization of changing incidence of PA and AB since the beginning of OIF/OEF is limited.
Methods: This is a retrospective electronic records review of culture/susceptibility testing results (Vitek I/II - Biomérieux, Durham, NC) of patients admitted to a 121 bed tertiary care level I trauma center in San Antonio, TX from 1/2001 - 12/2008. MDR defined as first isolate resistance to ≥ 3 classes of antimicrobial agents (β-lactams, carbapenems, aminoglycosides and quinolones).
Results: During the 7 year study period there were 1,605 (73%) AB and 842 (21%) PA isolates recovered from 3,333 OIF/OEF patients and 605 (23%) AB and 3,251 (79%) PA isolated from 124,205 local civilian admissions. Compared to local patients for the 2 most active antibiotics, OIF/OEF first isolate AB was less susceptible to imipenem (58% vs. 80%) and ampicillin/sulbactam (30% vs. 64%) and accounted for more MDR isolates (52% vs. 20%); PA first isolates were less susceptible to piperacillin/tazobactam (66% vs. 82%) and imipenem (32% vs. 72%) with 15 (8%) MDR isolates vs. 42 (3%). The AB culture rate for OIF/OEF patients decreased each year (2004 to 2008) from 19% to 5% and 10% to 2% for PA with a concomitant increase in MDR AB from 4% to 55% and MDR PA increased from 2% to 11%. From 2001 to 2008 the local civilian AB culture rate remained stable at 0.3% while PA decreased from 2.5% to 1.0%. A concomitant increase in MDR AB (4% to 39%) and MDR PA (3% to 8%) was also noted.
Conclusion: Treatment of OIF/OEF combat casualties led to an increase of MDR AB and MDR PA in the facility and presents a formidable challenge to the management of critically ill patients. Continued aggressive infection control practices and active culture surveillance are needed to limit the spread of these organisms within military medical centers.
Wade Aldous, PhD1, Edward Keen, PhD2, Clinton K. Murray, MD3, Brian Robinson, MS1 and  E. F. Keen, None..
B. J. Robinson, None..
C. K. Murray, None..
W. K. Aldous, None., (1)Brooke Army Medical Center, Ft Sam Houston, TX, (2)Brooke Army Medical Center, Fort Sam Houston, TX, (3)Brooke Army Medical Center, Ft. Sam Houston, TX