MOLECULAR EPIDEMIOLOGY OF PSEUDOMONAS AERUGINOSA AT A TERTIARY CARE HOSPITAL, SOUTHERN THAILAND

Phanvasri Saengsuwan1, Narongdet Kositpantawong2, Natnicha Ingviya3 and Kamonnut Singkhamanan 1

Abstract

Pseudomonas aeruginosa (n = 112) isolates from various clinical specimens of hospitalized patients in Songklanagarind Hospital, southern Thailand from February 2012 to January 2013 were analyzed for susceptibility to 10 different antibiotics using a disk diffusion method and genetic relatedness by a pulsed-field gel electrophoretic (PFGE). Half of the strains were from sputum samples mainly of infected patients with cardiovascular disease. P. aeruginosa infection is significantly associated with age and length of hospital stay (p-value <0.029). P. aeruginosa strains were equally sensitive (75-95%) to the four classes of antibiotics commonly used in Songklanagarind Hospital. Highest rate of resistance was to norfloxacin (43%) and no resistance to colistin was detected. Multidrug- and extensively drug-resistant P. aeruginosa (MDR-PA and XDR-PA) constituted 18% and 6%, respectively of the strains. PFGE DNA profiling revealed ?70 relatedness among the strains, clustering into seven groups (A-G). The predominant group A and E (38 and 32% of typeable strains respectively) contained 21% of MDR-PA and 11% of XDR-PA strains. It was noticeable 40% of MDR and XDR-PA strains were from patients in intensive care unit and medical ward. In conclusion, the study shows the usefulness of PFGE DNA profiling in molecular epidemiological investigation of nosocomial P. aeruginosa infection allowing implementation of appropriate transmission control and prevention strategies.