Objective: To assess factors associated with multi-drug resistant Acinetobacter baumannii (MDR-AB) nosocomial infection.
Material and Method: This hospital-based case control study was conducted in patients admitted to Siriraj Hospital, Bangkok, Thailand between January 1, 2005 and December 31, 2005. The study population consisted of 155 cases with MDR-AB nosocomial infection and 310 controls without nosocomial infection. The cases were matched with controls by age and ward of admission with a ratio of 1:2.
Results: The average age of the present study population was 63.5 + 18.7 years among cases and 62.9 + 18.2 years among controls. The mean of length of stay in hospital among cases was 4.9 + 1.4 weeks and controls 1.8 + 1.0 weeks. The most common site of MDR-AB nosocomial infection was lower respiratory tract (74.8%). The antimicrobial susceptibility of MDR-AB was 3.9% to cetriaxone and 42.1% to cefoperazone/sulbactam. Multiple logistic regression analysis showed the following associated factors with MDR-AB nosocomial infection: duration of admission prior to MDR-AB nosocomial infection > 1 week (OR = 2.06; 95%CI 1.09-3.89), indwelling urinary catheter > 1 week (OR = 8.24; 95%CI 3.81-17.82), mechanical ventilation >1 week (OR = 5.73; 95%CI 2.96-11.10), central venous line > 1 week (OR = 3.29; 95%CI 1.48-7.31), nasogastric intubation > 1 week (OR = 6.22; 95%CI 3.24-11.93), prior administration of 3rd-4th generation cephalosporins (OR = 1.80; 95%CI 1.04-3.13), metrodazole (OR = 2.59; 95%CI 1.21-5.56), and piperacillin-tazobactam (OR = 4.68; 95%CI 1.93-11.32).
Conclusion: A case-control study in medical and surgical patients in Siriraj Hospital in 2005 revealed risk factors for AB nosocomial infection. Prolonged admission of more than 2 weeks, use of devices, and prior treatment with certain antimicrobials were found to be significant risk factors for the infection. To reduce the infection, strict infection control measures must be applied to the patients with these risk factors. Education to medical personnel and enforcement of infection control practices are all needed to reduce antimicrobial resistant bacterial nosocomial infection.

Keywords: Risk factors, Multidrug-resistant, Acinetobacter baumannii, Nosocomial Infection