Fungal colonization and invasive fungal infections following allogeneic BMT using metronidazole, ciprofloxacin and fluconazole or ciprofloxacin and fluconazole as intestinal decontamination

Invasive fungal infections (IFI) are increasingly diagnosed in patients undergoing allogeneic BMT. We have previously shown that the addition of metronidazole to ciprofloxacin for gastrointestinal bacterial decontamination significantly reduces the incidence of grades II-IV aGVHD by reduction of the anaerobic intestinal bacterial flora. Here, we found that the combined use of ciprofloxacin, metronidazole and fluconazole as antifungal prophylaxis increased intestinal yeast colonization when compared to ciprofloxacin and fluconazole alone (P < 0.01). Based on the EORTC criteria, a total of 18 out of 134 study patients developed IFI: seven of 68 (10%) patients who received metronidazole compared to 11 of the 66 (17%) patients decontaminated without metronidazole developed IFI (log-rank P = 0.36). Lethal IFI occurred in two of seven patients receiving metronidazole and in four of 11 patients without anaerobic decontamination. In conclusion, bacterial intestinal decontamination using metronidazole as an antibiotic with activity against most anaerobic intestinal bacteria significantly increases the intestinal yeast burden without influencing the incidence of IFI in patients undergoing allogeneic BMT.