[Antibacterial activity of beta-lactam antibiotics against extended-spectrum beta-lactamase producing bacteria].
MICs of various beta-lactam antibiotics by themselves and in combination with beta-lactamase inhibitor (clavulanic acid) against extended spectrum beta-lactamase (ESBL) producing strains of Escherichia coli and Klebsiella pneumoniae which were isolated from clinical materials were investigated. Furthermore, based on the results obtained, a procedure to detect ESBL producing strains was proposed. The MICs of beta-lactam antibiotics against beta-lactamase producing strains were investigated. At first, beta-lactamase was investigated by the drug sensitivity pattern (MIC) to beta-lactam antibiotics and by the substrate profiles of beta-lactamase extracted from the transconjugant of E. coli K-12 strains. After that, we classified the beta-lactamase producing gene by PCR method. Furthermore, a proposal was made for an antibiotic to be used in the confirmation of mixed type beta-lactamase. The data obtained by the above investigations were compiled and used to determine the limit concentration of each beta-lactam against beta-lactamase producing strains including ESBL. By using beta-lactam antibiotics at the following concentrations, it is considered possible to classify beta-lactamase; ampicillin (64 micrograms/ml), ampicillin/clavulanic acid (32/5 micrograms/ml), piperacillin (64 micrograms/ml), cefotaxime (1 microgram/ml), cefpodoxime (2 micrograms/ml), ceftazidime (1 microgram/ml), cefmetazole (4 micrograms/ml), cefminox (2 micrograms/ml), cefepime (0.5 microgram/ml), aztreonam (1 microgram/ml) and imipeneme (1 microgram/ml). This method may be used as a reference in investigating the prevalence of beta-lactam resistant isolates by ESBL producing E. coli and K. pneumoniae.
Kuga
A
A
Department of Microbiology, Kitasato University School of Medicine.
Yano
H
H
Okamoto
R
R
Sato
Y
Y
Miyata
A
A
Inoue
M
M
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D019818:Clavulanic Acid / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004352:Drug Resistance, Microbial; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects* / Q000201:enzymology / Q000302:isolation & purification; D006801:Humans; D007711:Klebsiella pneumoniae / Q000187:drug effects* / Q000201:enzymology / Q000302:isolation & purification; D013379:Substrate Specificity; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000235:genetics
D000900:Anti-Bacterial Agents; D004791:Enzyme Inhibitors; D065093:beta-Lactamase Inhibitors; D019818:Clavulanic Acid; D001618:beta-Lactamases