Aim: To determine the effect of trimethoprim/sulphamethoxazole treatment on the natural population of lactic acid bacteria in the intestinal tract and to determine if any of the strains developed resistance to antibiotics.
Methods: Lactic acid bacteria were isolated from stool samples of 100 children. The isolates were identified based on biochemical characteristics and DNA profiles obtained from polymerase chain reaction with genus- and species-specific primers. Resistance to sulphamethoxazole, streptomycin, compound sulphonamides, chloramphenicol and vancomycin was tested using the paper-disk method.
Results: The lactic acid bacteria were identified as Lactobacillus acidophilus, Lactobacillus brevis, Lactobacillus paracasei, Lactobacillus pentosus, Lactobacillus rhamnosus, Leuconostoc mesenteroides subsp. mesenteroides, Enterococcus spp. and Weissella spp. Lactobacillus plantarum and Bifidobacterium spp. were not isolated. All strains, except two, were sensitive to chloramphenicol and streptomycin. Thirty-five percent of the isolates were resistant to vancomycin, 50% to compound sulphonamides and 66% to sulphamethoxazole.
Conclusion: Treatment with trimethoprim/sulphamethoxazole repressed a large number of lactic acid bacteria normally present in the intestinal tract of children. A number of strains were resistant to sulphamethoxazole and may be used as probiotics to correct the imbalance in lactic acid bacteria.