Isolation of Klebsiella Oxytoca Clinical Isolate Producing AmpC beta-lactamase, DHA-1.
- Author:
Wonkeun SONG
1
;
Jae Seok KIM
;
Han Sung KIM
;
Tae Jae LEE
;
Min Jeong PARK
;
In Heon PARK
;
Kyu Man LEE
Author Information
1. Department of Laboratory Medicine, Hallym University College of Medicine, Seoul, Korea. swonkeun@hallym.or.kr
- Publication Type:Original Article
- Keywords:
Klebsiella oxytoca;
inducible;
AmpC beta-lactamase;
DHA-1
- MeSH:
Amino Acid Sequence;
Ampicillin;
beta-Lactam Resistance;
beta-Lactamases*;
Cefoxitin;
Ceftazidime;
Cephalothin;
Clavulanic Acid;
Diffusion;
Escherichia coli;
Humans;
Klebsiella oxytoca*;
Klebsiella*;
Korea;
Phenotype;
Plasmids;
Polymerase Chain Reaction;
Sequence Analysis;
Sequence Analysis, DNA;
Wounds and Injuries
- From:Korean Journal of Clinical Microbiology
2004;7(2):124-129
- CountryRepublic of Korea
- Language:Korean
-
Abstract:
BACKGROUND: Klebsiella oxytoca strain exhibiting an unusual inducible beta-lactam resistance phenotype was isolated from a wound specimen of a patient at a university hospital in August 2002. The isolate was resistant to ampicillin, ampicillin-sulbactam, cephalothin, cefoxitin, and demonstrated reduced inhibition zone diameters for ceftazidime in combination with clavulanate versus those for ceftazidime when tested alone. METHODS: Antimicrobial susceptibilities were tested using the Etest and disk diffusion method. AmpC beta-lactamase production was determined by modified Hodge test. The disk antagonism method was used to detect inducibility of beta-lactamase. Conjugation experiments were performed by the filter mating method using the recipient Escherichia coli J53 Azir strain. PCR and DNA sequencing of DHA-specific PCR products were tested. RESULTS: The double disk synergy test was negative and the modified Hodge test was positive for the K. oxytoca isolate. Antagonism was observed between cefoxitin and oxyimino-cephalosporins. Sequence analysis of the DHA-specific PCR products revealed that they were identical to the amino acid sequence of the DHA-1 beta-lactamase. Transfer of the resistance by conjugation experiments was successful. CONCLUSIONS: We found a plasmid-mediated DHA-1 beta-lactamase-producing K. oxytoca possessing an unusual inducible beta-lactam resistance phenotype was found in a university hospital in Korea. The resistance phenotype was conferred by DHA-1 encoded by a self-transferable plasmid.
