In vitro susceptibility of diarrhoea producing gram negative enteric bacteria to sulfasalazine, 5-aminosalicylic acid, sulfapyridine and four quinolones. Brief report.

The in vitro susceptibility of diarrhoea producing Gram negative enteric bacteria to sulfasalazine, 5-aminosalicylic acid, sulfapyridine and four quinolones was investigated using an agar dilution method. All strains were resistant to 1600 micrograms/ml of sulfasalazine and 5-aminosalicylic acid. MIC range of sulfapyridine for Y. enterocolitica was 3.1-25 micrograms/ml (median:6.2) and for Salmonella 25-100 micrograms/ml (median: 100) Campylobacter jejuni/coli were less susceptible to sulfapyridine with MIC values ranging from 200 to 800 micrograms/ml. Shigella and three of five E. coli strains were resistant to 1600 micrograms/ml of sulfapyridine. Two strains of E. coli were inhibited by 25 micrograms/ml. All strains were fairly susceptible to enoxacin, ciprofloxacin, pefloxacin and ofloxacin. Cirpofloxacin was the most active drug on weight basis.