Studies on Enteric Pathogens Associated With Adult Diarrhoeal Out-Patients in Some Hospitals and Clinics of Addis Ababa: Antibiotic Resistance and Plasmid Profile Analysis

No Thumbnail Available



Journal Title

Journal ISSN

Volume Title


Addis Ababa University


700 diarrhoeal samples from adult out-patients, 335 from males and 365 from females, were collected from 4 hospitals (Tikur Anbesa, Zeuditu, Yekatit 12 and Menelik II) and Arada Clinic in Addia Abapa. Of the total samples, 394 (56.3%) yielded one or more etiologic agents. Of the positive samples, 191 (57%) were from males and 203 (55.6%) from females. Among 304 single infections, Salmonella was encountered in 13.2%, Shigella in 13.5%, Entamoeba histolytica in 33.5%, Giardia Lamblia in 28%, strongyloides stercoralis in 7.6% and Trichuris trichiura in 4.3%. In addition 75 double and 15 triple infections were found. No Cryptosporidium were identified in any of the samples. Differences in infection status among age groups and between sex were insignificant (p>O.Ol). Among 45 Salmonella isolates, serogroup C comprised 31.1%, B 24.4%, D 13.3%, S.typhi 15.6%, A 8.9% and E 6.7%. Susceptibility of Salmonella28.9%, to ampicillin 31.1%, isolates to tetracyclineto cephalothin 33.3%,wasto trimethoprim-sulfamethoxazole 42.2%, to chloramphnicol 53.3%, to kanamycin 46.1%, to carbenicillin 62.2%, to gentamicin 91.1% and to polymyxin B was 100%. Susceptibility of individual serogroups ranged from 0% to ampicillin and tetracycline up to 100% susceptibility to polymyxin B in serogroup A. Of the Salmonella isolates, 93% were resistant to one or more drugs with a total of 31 distinct resistance patterns (antibiograms). Frequently encountered antibiograms were those combinations 11hich contained ampicillin, tetracycline, cephalothin, kanamycin and trimethoprim-sulfamethoxazole. From 2 to 4 drug resistant strains from each serogroups of Salmonella were selected for plasmid profile analysis. All strains contained multiple plasmids which were larger than 21.2 kilobases (Kb) and several others ranging in sizes from 21.2 Kb to 1.8 Kb. Among 50 Shigella isolates, serogroup A comprised 28%, B 44%, C 18% and 0 10%. Susceptibility of Shigella isolates to tetracycline was 26%, to ampicillin 30%, to cephalothin 36%, to trimethprim-sulfamethoxazole 48%, to chloramphenicol 50%, carbencillin 72%, to kanamycin 80%, to nalidixic acid 86%, polymyxin B 90% and to gentamicin '-las 100%. Among all Shigella serogroups, least susceptibility was encountered to tetracycline and ampicillin while greatest susceptibility was observed to gentamicin, pOlymyxin B and nalidixic acid. Of all Shigella isolates, 98% were resistant to one or more drugs with a total of 32 distinct antibiograms. Frequently encountered antibiograms were those combinations which contained tetracycline, ampicillin, cephalothin and trimethoprimsulfamethoxazole. From 2 to 6 drug resistant isolates from each serogroups of Shigella, '-Iere selected for plasmid profile analysis. As in Salmonella, these also contained multiple plasmids which were larger than 21.2 Kb and others ranging in sizes from 21 Kb to 1.4 Kb. The importance of environmental sanitation, upgrading the knowledge of personal hygiene among the public and the use of prescribed antibiotics from proper pharmacies during necessities is recommended. The need for further research especially on plasmid profile analysis is stressed.