Two patients with malignant lymphoma underwent autologous bone marl ow transplantation on the protected environment-prophylactic antibiotic program. Antibiotic prophylaxis consisted of the oral administration of dibekacin (DKB) in a dosage of 250 mg every 6 hours, vancomycin (VCM) in a dosage of 500 mg every 6 hours, and nystatin in a dosage of 3 million units every 6 hours ( “DVN”). The effect of “DVN” on suppression of intestinal flora, hence on infection prevention was investigated.
Fecal flora was almost completely suppressed after one week of “DVN” intake, although organisms such as Lactobacillus or Candida, which were partially suppressed, remained as mono- or diflora during treatment with the antibiotics. Both patients were repopulated with a variety of organisms in similar concentrations in the pretreatment stools one week after cessation of “DVN” intakewhen they still stayed in the bioclean room, receiving sterile food. Rapid regrowth of enterobacteria was observed in one patient when he had transient difficulty in swallowing “DVN” because of nausea and vomiting due to the conditioning for transplantation.
On the other hand, oro-pharyngeal decontamination was more difficult to achieve than intestinal one.
Lactobacillus isolates from throat and stool, which originally had large MICs of DKB and VCM, became more resistant to DKB and lincomycin, which was inhalated in addition to “DVN” intake. The percent of administered dose of DKB recoverable in 24-hour urine specimens ranged from 0.7 to 2.7%, while urinary excretion of VCM was not seen.
Both patients developed mild nausea and excreted soft stools two to three times a day during “DVN” intake. These symptoms were aggravated by the conditioning for transplantion, but without any evidence of malabsorption. Both patients showed no evidence of bacterial or fungal infections, but they suffered from severe stomatitis due to Herpes simplex virus soon after transplantation. In one patient, the oral herpetic lesion having occurred despite interferon prophylaxis was remarkably relieved by the addition of nebulized interferon. The serum cholesterol concentrations of both patients were markedly reduced during treatment with oral antibiotics, of which DKB was inferred to be an etiologic agent.
In conclusion, “DVN” was thought to be one of the most excellent antibiotic regimens for intestinal decontamination.