Carbapenem resistance mechanism and risk factors of Pseudomonas aeruginosa clinical isolates from a University Hospital in Xi'an, China.
OBJECTIVE
Carbapenems are important agents for the therapy of Gram-negative bacillus infections, and the development of their resistance hampers effective therapeutic options. The purpose of this study was to assess the major mechanisms and risk factors leading to carbapenem resistance in clinical Pseudomonas aeruginosa isolates.


METHODS
Thirty-four clinical isolates with differing degrees of carbapenem susceptibility were analyzed for carbapenemase, porin, and efflux systems. Risk factor analysis was performed using a case-control study.


RESULTS
Eighteen of 24 carbapenem-resistant isolates were producers of carbapenemase. Diminished expression of oprD and overexpression of effluxes were present in five and seven carbapenem-resistant isolates, respectively. The number of days from admission to the day of positive culture and days of antibiotic apply were identified as the independent predictors of infection with carbapenem-resistant P. aeruginosa.


CONCLUSIONS
Carbapenemase production is a major mechanism of P. aeruginosa isolates involved in this study. Increased length of hospital stay and days of antibiotic application were the most important risk factors identified for carbapenem resistance.
Zhang
Jian-Fang
JF
Department of Microbiology, Fourth Military Medical University, Xi'an, P.R. China. fengql@fmmu.edu.cn
Chen
Bi-Liang
BL
Xin
Xiao-Yan
XY
Zhao
Hai-Bo
HB
Wang
Hong-Ying
HY
Song
Hui
H
Xu
Zhi-Kai
ZK
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D015780:Carbapenems / Q000494:pharmacology*; D016022:Case-Control Studies; D002681:China; D003428:Cross Infection / Q000382:microbiology; D017931:DNA Primers; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D005798:Genes, Bacterial; D006785:Hospitals, University; D006801:Humans; D018272:Porins / Q000235:genetics; D011552:Pseudomonas Infections / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012307:Risk Factors; D001618:beta-Lactamases / Q000032:analysis / Q000235:genetics / Q000378:metabolism
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D015780:Carbapenems; D017931:DNA Primers; D018272:Porins; C077157:OprD protein, Pseudomonas aeruginosa; D001618:beta-Lactamases; C063912:carbapenemase