Hospital-acquired infections mainly are caused by bacteria and have increased globally. The causative agents include Klebsiella pneumonia, Escherichia coli, Pseudomonas aeroginosa, Acinetobacter baumannii, Staphylococcus aureus, methicillinresistant S. aureus (MRSA), and Enterococci spp. Treatment has become more complicated; therefore, effective surveillance is essential in preventing spread. The authors investigated the epidemiology of strains isolated from Thammasat University Hospital, Thailand. Our results indicated a gradual increase in infected patients with hospital-acquired bacteria at Thammasat University Hospital. The highest number of infections was found in the neonatal intensive care unit (NICU) in 2013 (14.73%). Infections of less than 10% were also found in other units: Neonatal Intensive Care, General Male Internal Medicine, General Male Surgery, General Female Surgery, and Surgical Intensive Care. A. baumannii (MDR), P. aeruginosa, K. pneumoniae (ESBL), E. coli (ESBL), Candida
albicans, and MRSA were frequently detected. Urinary tract infections were the most common, from E. coli (ESBL), E. coli, C. albicans, P. aeruginosa and K. pneumoniae. Even if strains are not yet resistant, medical personnel should be vigilant and prevent patient-topatient infection.

Keywords: Hospital-acquired infections, Bacterial infections, Antibiotic resistance