Objective: To study the prevalence of nosocomial infection (NI).
Material and Method: A point prevalence study was done in 20 hospitals across the country in August 2006.
Results: The present study was done in 20 hospitals: three university, five regional, five provincial, and seven other hospitals. 9,865 patients were included. Male and female patients were almost equal in number with an average age of 42.7 years. The NI proportion was 6.5%, 7.0% in male and 5.9% in female patients. The prevalence rate of NI was highest in university and other hospitals (7.6%), followed by provincial (6.0%), and regional hospital (4.9%). There were two hospitals, one regional and one other hospital with NI prevalence rates over 10%. All three university hospitals had NI exceeding 7%. The infection rate was highest in ICU (22.6%), followed by surgical (6.8%), medical and orthopedic (6.7% each) departments. The commonest site of NI was lower respiratory tract (36.1%) followed by urinary tract (25.5%). Causative organisms were identified in 70.8% of all sites of infection and over 63% were by bacteria. Gram-negative bacteria were responsible for 70.2% and gram-positive bacteria for 19.9% of all pathogens. Pseudomonas aeruginosa, Klebsiella spp., Acinetobacter baumannii, MRSA, and enterococci were the leading bacterial isolates. At the time of the present study, 47.0% of patients were receiving antimicrobials. Cephalosporins, penicillins, and aminoglycosides were most commonly used.
Conclusion: The prevalence rate of NI in Thailand in 2006 was 6.5%, similar to previous studies. Changes in NI rates in certain hospitals, even though subtle, need additional studies to improve the efficacy of NI control.

Keywords: Nosocomial infection, Prevalence, Thailand