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.

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.

Usefulness of pp65 antigenemia for the early diagnosis of cytomegalovirus disease in patients with AIDS

An observational cohort study was performed to assess the effectiveness of a cytomegalovirus antigenemia (CMV-Ag) assay designed to predict clinical CMV disease in patients with AIDS. Eighty-six HIV-infected patients with CD4+ cell counts of < 100/mm3, positive CMV IgG, and no previous CMV disease were enrolled. Thirty-eight (44%) patients had at least one positive CMV antigenemia test, ten of whom eventually developed CMV focal disease. CMV disease was diagnosed in 13 (15%) patients. The CMV antigenemia assay was positive in ten of these 13 patients. Using a cut-off value of five positive cells in every 150,000 leukocytes sampled, the CMV antigenemia assay had a positive predictive value of 89% and a negative predictive value of 94%. The median time from the first positive CMV antigenemia test to the onset of CMV disease was 102 days. CMV disease probability at 6 months in patients with a CMV antigenemia value > or = 5 was 77.8% versus 6% in patients with CMV antigenemia value < 5 (log-rank test = 48.345; P < 0.001). Several independent factors were associated with the development of CMV disease: CMV antigenemia > or = 5 cells (hazard ratio: 20.44), CD4+ count < or = 25/mm3 (HR: 3.12), and sexual transmission of HIV infection (hazard ratio, 3.15). CMV antigenemia seems to be a good predictor of CMV disease in patients with AIDS.

Development of quinolone-resistant strains of Escherichia coli in stools of patients with cirrhosis undergoing norfloxacin prophylaxis: clinical consequences

BACKGROUND/AIM

Norfloxacin prophylaxis decreases the incidence of bacterial infections in high-risk cirrhotic patients, but may promote the development of quinolone-resistant gram-negative bacteria in stools, and eventually lead to infections due to these bacteria. The aim of the study was to evaluate the prevalence of quinolone-resistant strains of E. coli in stools on admission, and the characteristics of any nosocomial infections.

METHODS

Eighty-three consecutively hospitalized cirrhotic patients were included in this prospective study. The presence of quinolone-resistant strains of E. coli in stools on admission, and the characteristics of any nosocomial infections were recorded.

RESULTS

Fourteen out of 83 patients (16.8%) showed quinolone-resistant E. coli in stools (Group I), and 69 did not (Group II). Thirteen out of 14 from Group I (92.8%) and 17/69 (24.6) from Group II had received primary or secondary prophylaxis with norfloxacin (p<0.001). During hospitalization, 12/12 (100%) of patients from Group I and 25/66 (37.8%) of patients from Group II underwent norfloxacin prophylaxis. Three bacterial infections in patients from Group I, 3 from Group II patients receiving norfloxacin and 16 from Group II patients not receiving norfloxacin were recorded (p<0.05). No infections due to quinolone-resistant E. coli were observed in patients colonized with these bacteria. Treatment with norfloxacin induced the development of quinolone-resistant E. coli in 6/14 (42.8%) patients in a mean time of 18.5+/-9.8 days.

CONCLUSIONS

The development of quinolone-resistant strains of E. coli is significantly associated with previous administration of norfloxacin prophylaxis. However, in our series this fact is not associated with an increased incidence of quinolone-resistant E. coli or other gram-negative infections.