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.
Aim: 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.