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Volume 39, Number 2, April 2006

OXA-type beta-lactamases among extended-spectrum cephalosporin-resistant Pseudomonas aeruginosa isolates in a university hospital in southern Taiwan

Jing-Jou Yan, Shu-Huei Tsai, Chin-Luan Chuang, Jiunn-Jong Wu
Department of Pathology, National Cheng Kung University Hospital, Tainan; and Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan, Taiwan

Received: March 17, 2005    Revised: May 21, 2005    Accepted: June 15, 2005   


Corresponding author:

February 20, 2005 Revised: March 11, 2005 Accepted: March 17, 2005


Background and purpose: 

Data on the epidemiology of OXA-type extended-spectrum beta (β)-lactamases (ESBLs) are limited due to difficulty of identification by routine microbiology laboratories. We determined the prevalence rate of OXA-type β-lactamases among extended-spectrum cephalosporin (ESC)-non-susceptible Pseudomonas aeruginosa isolates at a university hospital in southern Taiwan.




A total of 1294 ESC-non-susceptible P. aeruginosa isolates collected between 1989 and 1996 (n = 42) and between December 1999 and December 2002 (n = 1252) were analyzed by polymerase chain reaction assays with primers specific for blaOXA genes and isoelectric focusing.




Forty five isolates (3.5%) were found to produce an OXA-type β-lactamase. Overall, 2 OXA-type ESBLs, OXA-14 (n = 2) and OXA-17 (n = 35), were detected in 37 (2.9%) isolates, and the OXA-10-type narrow-spectrum β-lactamase was found in 8 (0.6%) isolates. OXA-10 and the 2 OXA-type ESBLs were detected in 6 (14.3%) and 4 (9.5%) of 42 ESC-non-susceptible isolates collected between 1989 and 1996. OXA-10 and OXA-17 were detected in 2 (0.2%) and 33 (2.6%) of 1252 ESC-non-susceptible isolates collected between December 1999 and December 2002.




These data indicate that OXA-17 was the most common OXA-type ESBL and that OXA-type β-lactamases have decreased in ESC-non-susceptible P. aeruginosa at this hospital in recent years. Pulsed-field gel electrophoresis revealed clonal diversity among the OXA-producing isolates.



Key words:

beta-Lactamases, cephalosporin resistance, microbial sensitivity tests, polymerase chain reaction, Pseudomonas aeruginosa



J Microbiol Immunol Infect 2006;39:130-134.