RAPID EMERGENCE OF QUINOLONE RESISTANCE IN CIRRHOTIC-PATIENTS TREATEDWITH NORFLOXACIN TO PREVENT SPONTANEOUS BACTERIAL PERITONITIS

We carried out quantitative culturing of stools from 31 hospitalized a lcoholic patients with cirrhosis and ascites, before treatment with 40 0 mg of norfloxacin per day, weekly for the first month, and then ever y 2 weeks thereafter for 15 to 229 days (median, 54 days). Members of the family Enterobacteriaceae virtually disappeared from the stools (< 10(2)/g), but treatment had little effect on enterococci. No selection of resistant organisms occurred in 15 patients, but the remaining 16 patients developed fecal organisms resistant to fluoroquinolones betwe en days 14 and 43 of treatment (median, 25 days). Staphylococcus aureu s was isolated four times, coagulase-negative Staphylococcus spp. were isolated six times, Citrobacter freundii was isolated four times, Ent erobacter cloacae was isolated three times, Klebsiella oxytoca was iso lated twice, Proteus rettgeri was isolated once, and untypeable strept ococci were isolated six times. Some isolates persisted, while others were transient (one to seven consecutively positive cultures). The MIC s of four quinolones (nalidixic acid, norfloxacin, ofloxacin, and cipr ofloxacin) were determined by use of experimental microwell strips (AT B CMI; Biomerieux S.A.). All the strains isolated before treatment wer e susceptible to the four quinolones, with low MICs, whereas those iso lated during norfloxacin treatment were highly resistant. Long-term no rfloxacin administration thus carries a risk of disturbing the bacteri al ecology in these patients, suggesting that digestive decontaminatio n should no longer be prescribed routinely to cirrhotic patients with ascites.