Norfloxacin decreases bacterial adherence of quinolone-resistant strains of Escherichia coli isolated from patients with cirrhosis.
BACKGROUND
Long-term administration of norfloxacin is recommended for secondary prophylaxis of spontaneous bacterial peritonitis in cirrhosis, but it may be associated with the development of quinolone-resistant bacteria in stools. However, these bacteria rarely cause infections.


OBJECTIVE
To assess bacterial adherence of either quinolone-sensitive or -resistant Escherichia coli obtained from stools of cirrhotic patients, as one of the main virulence factors, and its variations when sub-minimum inhibitory concentration of norfloxacin were added to the medium.


METHODS
E. coli strains were co-cultured with oral epithelial cells obtained from patients in presence/absence of norfloxacin. Bacterial adherence was measured as percentage of cells exhibiting positive adherence and the number of bacteria attached to epithelial cells.


RESULTS
37 sensitive and 22 resistant E. coli strains were studied. Bacterial adherence was similar in both series (78% vs. 81%, P = N.S.), and these percentages were similarly and significantly reduced when subminimum inhibitory concentration of norfloxacin was added to the culture medium (P < 0.001).


CONCLUSIONS
Bacterial adherence of E. coli obtained from patients with cirrhosis is unrelated to the sensitivity/resistance to quinolones, and is similarly reduced in both cases when subminimum inhibitory concentration of norfloxacin is added to the medium.
Gascón
I
I
Microbiology Department, Hospital General Universitario, 03010 Alicante, Spain.
Pascual
S
S
Plazas
J
J
Sánchez
J
J
Francés
R
R
Más
P
P
Zapater
P
P
Pérez-Mateo
M
M
Such
J
J
D000890:Anti-Infective Agents / Q000494:pharmacology*; D001422:Bacterial Adhesion / Q000187:drug effects*; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects*; D006801:Humans; D020128:Inhibitory Concentration 50; D008103:Liver Cirrhosis / Q000382:microbiology*; D009061:Mouth Mucosa / Q000382:microbiology; D009643:Norfloxacin / Q000494:pharmacology*; D015363:Quinolones / Q000627:therapeutic use*
D000890:Anti-Infective Agents; D015363:Quinolones; D009643:Norfloxacin