Human studies to measure the effect of antibiotic residues.

This epidemiological study compares the frequency of resistant bacteria in stool microflora among vegetarians and nonvegetarians over a 12 month period. Two well characterized vegetarian populations (one in Boston, MA and the other in Loma Linda, CA) as well as appropriate controls were studied. No apparent differences in the prevalence of antibiotic resistance in the microflora were noted; however, vegetarians had a significantly greater incidence of multi-antibiotic resistance. E. coli of the same API biotype had the same frequency of antibiotic resistance in both vegetarians and nonvegetarians. Quantitative studies showed similar percents of tetracycline resistant facultative isolates and of "bacteroides." Klebsiella were more common in the stool of the nonvegetarians. As shown in previous studies, exposure to animal products either as meat eaters or production workers in a poultry abattoir was not associated with an increased incidence of resistant bacterial flora or infections caused by resistant strains.