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Volume 39, Number 4, August 2006

Extended-spectrum beta-lactamases in Taiwan: epidemiology, detection, treatment and infection control


Wen-Liang Yu, Yin-Ching Chuang, Jan Walther-Rasmussen
Department of Intensive Care Medicine, Chi-Mei Medical Center, Tainan County; Department of Medicine, Taipei Medical University, Taipei; Department of Internal Medicine, Chi-Mei Medical Center, Tainan County, Taiwan; and Department of Clinical Microbiology, The National University Hospital, Copenhagen, Denmark

Received: March 22, 2006       Accepted: March 29, 2006   

 

Corresponding author:

Dr. Jan Walther-Rasmussen, Department of Clinical Microbiology, 9301, Juliane Mariesvej 22, The National University Hospital, DK-2100, Copenhagen O, Denmark. E-mail: jawalras@mail.tele.dk This e-mail address is being protected from spam bots, you need JavaScript enabled to view it

 



 

Methods:

Extended-spectrum beta-lactamases (ESBLs) efficiently hydrolyze extended-spectrum beta-lactams such as cefotaxime, ceftriaxone, ceftazidime, and aztreonam. ESBLs are most often plasmid-mediated. In Taiwan , the prevalence of ESBLs in bacteria has risen, ranging from 8.5 to 29.8% in Klebsiella pneumoniae and 1.5 to 16.7% in Escherichia coli isolates. The most prevalent types of ESBLs are SHV-5, SHV-12, CTX-M-3, and CTX-M-14 in isolates of K. pneumoniae and E. coli , with differences between institutions. SHV-12 and CTX-M-3 have been reported as the most common ESBLs in isolates of Enterobacter cloacae and Serratia marcescens , respectively. Molecular epidemiology studies suggest that the ESBL-encoding genes have been disseminated either by proliferation of epidemic strains or by transfer of plasmids carrying the resistance traits. The current ESBL screen guidelines of the Clinical and Laboratory Standards Institute (formerly National Committee for Clinical Laboratory Standards) are issued for E. coli , Klebsiella spp., and Proteus mirabilis . Owing to the lack of standard methods, it remains difficult to assure the presence of ESBL in an isolate co-harboring an AmpC beta-lactamase, particularly in cases where the latter is produced in larger amounts than the former. Empirical therapy with piperacillin-tazobactam to replace third-generation cephalosporins may help to reduce the occurrence of ESBLs in an institution with a high prevalence of ESBL producers. Carbapenems remain the drugs of choice for serious infections caused by ESBL-producing organisms. To retard the selection for carbapenem-resistant bacteria, 7-alpha-methoxy beta-lactams or fourth-generation cephalosporins can be therapeutic alternatives for mild-to-moderate infections provided that the pharmacokinetic and pharmacodynamic target can be easily achieved.

 



 

Key words:

AmpC beta-lactamase, beta-lactam resistance, beta-lactamases, Enterobacteriaceae infections, prevalence, review

 



 

J Microbiol Immunol Infect 2006;39:264-277.