Prevention of bacteraemia by systemic ciprofloxacin treatment in rat cytomegalovirus-infected immunocompromised rats.

After total body irradiation (TBI) and subsequent rat cytomegalovirus (RCMV) infection rats developed severe neutropenia and in 90% of these animals Gram-negative bacteraemia was observed. Neutropenia was less severe (P < 0.01) and bacteraemia was not recorded (P < 0.01) in uninfected irradiated control groups. The effect of selective bowel decontamination (SBD) on the bowel flora and the incidence of bacteraemia in RCMV-infected irradiated rats was studied. Animals received ciprofloxacin 2 mg/kg/day, administered by either the oral or the subcutaneous route. After either treatment regimens the numbers of Enterobacteriaceae in the caecum and colon were reduced significantly (from 10(7) to < 10(2) g of faeces), while the total numbers of facultatively aerobic and obligatory anaerobic bacteria and the number of enterococci in the faeces was unaffected when measured 1, 3 and 7 days after the onset of treatment. The effect of ciprofloxacin treatment on the incidence of bacteraemia was recorded in RCMV-infected irradiated groups. Blood and organ cultures were taken 10 days after virus inoculation. The rate of bacteraemia decreased from 80% in untreated RCMV-infected irradiated rats affected by severe RCMV disease to < 10% in the ciprofloxacin treated groups (P < 0.01). The route of treatment did not influence these results. The uninfected irradiated and infected non-irradiated control groups showed no bacteraemia. It is concluded that symptomatic RCMV infection induces severe neutropenia, which predisposes to a high rate of Gram-negative bacteraemia, which can be prevented by eradication of the Gram-negative aerobic bacteria by means of SBD with ciprofloxacin. Systemic treatment seems to be superior for the control of Enterobacteriaceae. This may be especially useful for patients, who cannot be treated effectively by the oral route because of intestinal stasis.