In vitro activity of beta-lactams and quinolones against AmpC beta-lactamase-producing Escherichia coli.
We studied the antimicrobial susceptibility of AmpC beta-lactamase-producing Escherichia coli isolates collected at ten medical institutions in the Kinki area of Japan during a 6-month period (November 2002 through April 2003). Of 2845 E. coli isolates tested, 29 (1.0%) showed a minimum inhibitory concentration (MIC) for cefazolin of more than 8 microg/ml and were three-dimensional extract test positive. In standard inoculum susceptibility tests against these 29 strains, the MIC90s for the four carbapenems tested ranged from 0.06 microg/ml to 0.5 microg/ml, and these compounds were more active than the other beta-lactams, with meropenem being the most active. The MIC90s for beta-lactams, except carbapenems, ranged from 4 microg/ml to 32 microg/ml, with cefepime being the most active. In high inoculum susceptibility tests against these strains, the MIC90s for the four carbapenems and cefepime were 8 microg/ml or less, and these compounds were more active than other beta-lactams. The MIC90s for beta-lactams, except carbapenems and cefepime, were 32 microg/ml or more. The MIC90s for the five quinolones tested ranged from 4 microg/ml to 16 microg/ml, and the order of increasing susceptibility was ciprofloxacin > levofloxacin, gatifloxacin and pazufloxacin > prulifloxacin.
Yamasaki
Katsutoshi
K
Clinical Laboratory, Wakayama Rosai Hospital, 435 Koya, Wakayama, 640-8345, Japan. kyamasaki@gaia.eonet.ne.jp
Komatsu
Masaru
M
Shimakawa
Koichi
K
Satoh
Kaori
K
Nishio
Hisaaki
H
Sueyoshi
Noriyuki
N
Toyokawa
Masahiro
M
Sakamoto
Masako
M
Higuchi
Takeshi
T
Wada
Yasunao
Y
Kofuku
Tomomi
T
Orita
Tamaki
T
Yamashita
Tomonari
T
Kinoshita
Shohiro
S
Aihara
Masanori
M
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000378:metabolism; D002437:Cefazolin / Q000494:pharmacology*; D003428:Cross Infection; D004926:Escherichia coli / Q000187:drug effects* / Q000378:metabolism; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000382:microbiology; D006761:Hospitals; D006801:Humans; D007564:Japan; D008826:Microbial Sensitivity Tests; D015363:Quinolones / Q000494:pharmacology; D001618:beta-Lactamases / Q000378:metabolism
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D015363:Quinolones; C048795:AmpC beta-lactamases; D001618:beta-Lactamases; D002437:Cefazolin