Risk Factors for Gastrointestinal Colonization and Acquisition of Carbapenem-Resistant Gram-Negative Bacteria among Patients in Intensive Care Units in Thailand

This study was conducted to investigate the prevalence of and risk factors for colonization and acquisition of carbapenem-resistant (CR) Gram-negative bacteria (GNB) among patients admitted to intensive care units (ICUs) in two tertiary care hospitals in northern Thailand. Screening of rectal swab specimens for CR-GNB was performed on patients at ICU admission and discharge. The phenotypes and genotypes of all isolates were determined. Risk factors were analyzed by logistic regression analysis. The overall carriage rate of CR-GNB at admission was 11.6% (32/275), with the most predominant species carried being Acinetobacter baumannii ( n = 15), followed by Klebsiella pneumoniae ( n = 9). The risk factor for CR-GNB colonization was hospitalization within the previous 6 months ( P = 0.002). During the ICU stay, the rate of CR-GNB acquisition was 25.2% (52/206), with the most predominant species carried being A. baumannii ( n = 28) and K. pneumoniae ( n = 13). Risk factors associated with CR-GNB acquisition were the use of an enteral feeding tube ( P = 0.008) and administration of third-generation cephalosporins ( P = 0.032) and carbapenems ( P = 0.045). The most common carbapenemase genes in A. baumannii and K. pneumoniae were bla OXA-23/51 and bla NDM , respectively. Patient-to-patient transmission was demonstrated in three cases, resulting in the acquisition of CR A. baumannii (2 cases) and K. pneumoniae (1 case) isolates from other patients who were admitted during the same period of time. This is the first Indochinese study screening patients, examining patients for the carriage of CR-GNB, and further demonstrating the transfer of CR-GNB isolates in ICUs. Our study suggests that effective infection control measures are required to limit the spread of CR-GNB within hospitals.