RESUMEN
The purpose of this investigation was to assess the effects of preoperative administration of parenteral antibiotics with or without concomitant preoperative administration of oral antibiotics on the colonic mucosal-related microflora. Thirty-one patients were studied in a prospective fashion. Group A patients (n = 8) had colonoscopic mucosal biopsies performed after mechanical bowel preparation. Group B patients (n = 5) received neomycin and erythromycin (NE), 1 g each following mechanical bowel preparation, at 1, 2, and 11 p.m. the evening prior to either elective colon resection (n = 2) or prior to colonoscopic biopsy (n = 3). Emergent trauma patients who had left colon or sigmoid perforations due to gunshot wounds requiring segmental resection comprised group C (n = 7). These patients received cefoxitin or cefotetan 2 g intravenously preoperatively. Individuals in group D (n = 11) all had elective left hemicolectomies or sigmoid resections due to nonobstructing malignancies. These patients underwent the same regimen as group B patients in addition to receiving intravenous cefoxitin perioperatively. Quantitative and qualitative bacterial cultures as well as scanning electron microscopy (SEM) were used to study the mucosa-associated flora. Tissue for culture and SEM were obtained from the pathologic specimen immediately after removal. The interval between the dosage of parenteral antibiotics to tissue removal was 3 hours in both groups. Anaerobic and aerobic counts were suppressed the greatest in patients receiving both oral and parenteral antibiotics (p = 0.0001). Mean anaerobic counts decreased from 3.4 X 10(7) in group A to 1.8 X 10(2) (mean cfu/g) in group D patients. Mean aerobic counts in group A decreased from 3.7 X 10(6) to 64 (mean cfu/g) in group D.(ABSTRACT TRUNCATED AT 250 WORDS)