Detection of Extended-spectrum beta-lactamase in Klebsiella pneumoniae.
- Author:
Soo Youn LEE
;
Sun Hwa LEE
;
Chik Hyun PAI
- Publication Type:Original Article
- MeSH:
Agar;
Anti-Bacterial Agents;
Aztreonam;
Bacteremia;
beta-Lactam Resistance;
beta-Lactamases*;
Cefotaxime;
Ceftazidime;
Ceftriaxone;
Cephalosporins;
Clavulanic Acid;
Disease Outbreaks;
Drug Resistance, Microbial;
Hospitalization;
Humans;
Incidence;
Intensive Care Units;
Klebsiella pneumoniae*;
Klebsiella*;
Mass Screening;
Medical Records;
Penicillins;
Pneumonia;
Risk Factors
- From:Korean Journal of Clinical Pathology
1997;17(6):1076-1088
- CountryRepublic of Korea
- Language:Korean
-
Abstract:
BACKGROUNDS : Extended spectrum beta-lactamases (ESBL) are plasmid-mediated enzymes that confer broad-spectrum resistance to aztreonam, most penicillins, and cephalosporins including ceftazidime, cefotaxime and ceftriaxone. But with most routine susceptibility tests, ESBL-producing strains may not appear to be resistant, which makes it difficult to predict the effectiveness of the beta-lactam agents. In this study, we performed several test procedures to detect ESBL in blood isolates of Klebsiella pneumoniae and examined the risk factors for bacteremia due to ESBL-producing K. pneumoniae. MATERIALS AND METHODS: Of 87 blood culture Isolates of K. pneumoniae during the first 7 month of 1996, 39 showed reduced susceptibilities to at least one of the 4 antibiotics, aztreonam, cefotaxime, ceftazidime and ceftriaxone. Twenty-three of the 39 isolates were assailable for screening for ESBL. Antibiotic resistance was tested by the agar dilution method and beta-lactamase assay using nitrocefin disks. Effect of beta-lactamase inhibition was examined by the doubledisk synergy test using aztreonam, cefotakime, ceftazldime, and ticarc illin/clavulanate disks and by ESBL Etest involving ceftazidime and cert tazidime/clavulanate. Ability to transfer the beta-lactam resistance was tested by conjugation. We also reviewed the medical records of the patients with K. pneumoniae. (21 with and 41 without ESBL) bacteremia to ananlyze their clinical characteristics. RESULTS: Of 23 strains tested, reduced susceptibilities to cefotaxime, aztreon am and ceftazidime were shown in 23, 18, and 18 strains, respectively. All strains were positive for beta-lactamase and its activity was trasfered to E. coli in all strains. Activities of beta-lactamases were shown to be inhibited by clavulanate in 21 strains by the double-disk method, but in only 15 strains by the ESBL Etest. Nineteen of 21 bacteremia were nosocomially acquired. ESBL-producing strains were associated with length of hospitalization, stay in intensive care unit, use of invasive procedures and administration of antibiotics Including penicillins and third-generation cephalosporins. CONCLUSIONS: Although an increasing incidence of and outbreaks by ESBL-producing strains are reported, detection of ESBLs has proved to be difficult. Using several testing methods such as double-disk synergy test, ESBL Etest and conjugation, we estimated that 40.9% of blood isolates of K. pneumoniae produce ESBL. We should pursue for more sensitive and reliable screening methods for the detection of ESBL.
