title: Nosocomial spread of class 1 integron-carrying extensively drug-resistant Pseudomonas aeruginosa isolates in a Thai hospital.
abstract: Fifty non-duplicate multiresistant isolates of Pseudomonas aeruginosa from a regional hospital in Northern Thailand were investigated for their antimicrobial susceptibility, presence of class 1 integrons and arrangement of gene cassettes as well as their genetic relationships. All but one isolate were classified as extensively drug-resistant P. aeruginosa (XDR-PA). Forty-one isolates (82%) were found to carry class 1 integrons. Amplification of the variable regions of class 1 integrons revealed seven diverse bands ranging in size from 0.7 kb to 7.0 kb. Sequence analysis of class 1 integron variable regions revealed the presence of several gene cassettes associated with resistance to aminoglycosides (aac, aad and aph), including the aac(3)-Ic cassette reported for the first time in Thailand. Gene cassettes encoding resistance to chloramphenicol (cmlA), β-lactams (bla(PSE), bla(OXA) and bla(VEB)) and rifampicin (arr) were found. The putative small multidrug resistance protein (smr) and an open-reading frame with unknown function (orfD) were also detected. The aadA6-orfD cassette array was the most common integron found in this study. Integron-positive isolates had higher frequencies of antimicrobial resistance than isolates lacking integrons. Pulsed-field gel electrophoresis (PFGE) demonstrated the occurrence of horizontal gene transfer. Interestingly, a large number of XDR-PA isolates carrying identical integrons clearly exhibited the same PFGE pattern, indicating nosocomial spread of these isolates. The presence of XDR-PA carrying class 1 integrons is implicated in the possible spread of drug-resistant organisms, therefore screening for integron-positive P. aeruginosa might be necessary for protection against nosocomial infection.
authors.affiliation: Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University, Phitsanulok 65000, Thailand.
authors.forename: Anong
authors.initials: A
authors.lastname: Kiddee
authors.forename: Kritsada
authors.initials: K
authors.lastname: Henghiranyawong
authors.forename: Jutharak
authors.initials: J
authors.lastname: Yimsabai
authors.forename: Mujarin
authors.initials: M
authors.lastname: Tiloklurs
authors.forename: Pannika R
authors.initials: PR
authors.lastname: Niumsup
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D022761:Gene Transfer, Horizontal; D005798:Genes, Bacterial; D006761:Hospitals; D006801:Humans; D032023:Integrons; D008826:Microbial Sensitivity Tests; D017720:Molecular Epidemiology; D011552:Pseudomonas Infections / Q000453:epidemiology* / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D017422:Sequence Analysis, DNA; D013785:Thailand / Q000453:epidemiology
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial
keywords: Extensively drug-resistant; Integron; Nosocomial spread; Pseudomonas aeruginosa