In vitro bactericidal activity of antimicrobial agents against enterohaemorrhagic Escherichia coli.
OBJECTIVE
In vitro bactericidal activity of four antimicrobial agents was determined against nine strains of enterohaemorrhagic Escherichia coli.


METHODS
Pulsed-field gel electrophoresis was carried out with the Bio-Rad Gene Path system. Each antimicrobial agent was added to logarithmic phase of enterohaemorrhagic E. coli (four strains of E. coli O157:H7, two of E. coli O26, two of E. coli O111, and one of E. coli O165) in broth to obtain a concentration of 10 or 50 mg/L, and viable cells were counted after 1, 2, 6 and 24 h.


RESULTS
All nine strains were confirmed to differ in their DNA pattern by pulsed-field gel electrophoresis. Norfloxacin at concentrations of 10 and 50 mg/L had bactericidal effects on all nine strains of enterohaemorrhagic E. coli. However, cefoperazone, kanamycin and fosfomycin had no bactericidal effects on some strains. In particular, after addition of 10 mg/L fosfomycin or kanamycin, four of the nine strains showed proliferation.


CONCLUSIONS
Norfloxacin had marked bactericidal effects on enterohaemorrhagic E. coli. This information could be of value in planning randomized clinical trials of antimicrobial agents as treatment for enterohaemorrhagic E. coli infection.
Department of Pharmacy, Yamaguchi University Hospital, 1-1-1 Minamikogushi, Ube 755-8505, Japan.
Shigeharu
S
Oie
Junko
J
Ishitobi
Akihiro
A
Sawa
Masaaki
M
Tomita
Akira
A
Kamiya
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002438:Cefoperazone / Q000494:pharmacology; D016521:Electrophoresis, Gel, Pulsed-Field; D019453:Escherichia coli O157 / Q000187:drug effects* / Q000235:genetics; D005578:Fosfomycin / Q000494:pharmacology; D007612:Kanamycin / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D009643:Norfloxacin / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D005578:Fosfomycin; D007612:Kanamycin; D002438:Cefoperazone; D009643:Norfloxacin