The present study was carried to reveal the role of plasmid encoding multiple drug resistance on the sensitivity of salmonella causing enteric fever through the following studies (1) Antibiogram (2) plasmid profile (3) transfer of resistance determinant by conjugation with E.coli kl2 and transformation with Ecoli C600. One hundred salmonella strains were isolated from typhoid patients attending the Out Patient Clinic of Benha Fever Hospital during April 1993 to March 1995. The isolated salmonella strains were 48 S.typhi, 24 S.paralyphi A and 28 S.paratyphi B. The antibiogram of the isolated strains revealed that, 75/100 strains were completely sensitive to ampicillin (Pn), kanamycin (K), gentamycin (Gm), oxytetracyclin (00 sulphamethiazol (Th), co-trimoxazol (Sxt), norfloxacin (Nor), cephalaxin (Cl), naldexic acid (Na), chloramphenicol (C), cephradin (Ce), streptomycin (S), amikacin (An), neomycin (N), cephalothin ((f), piperacillin (Pr!), cefotaxim (Ctx) & ofloxacin (0fic). All the sensitive strains were plasmidless. All the resistance strains were resistant to C & Th and sensitive to Gm, Pn, Prl, K, N, Ofic & Nor. Plasmid analysis of 25 resistance strains produced 21 plasmids profiles. S.Ophi strains harboured from 1-8 plasmids with Mw. ranging from 1.2 to 7.1 megadalton (Mda); S paratyphi A strains harboured 1-4 plasmids with Mw. ranging from 1.2 to 5.4 Mda, S. paratyph B strains harboured from 1-7 plasmids with Mw. ranging from 1.2 to 5.4 Mda Genetic transfer process of sulphamethiazol resistance markers revealed that the means conjugation frequencies were 7 x 10-8, 6.9< 104 & 6.3 x 104 for S.typhi, S. paratyphi A & S. paratyphi B respectively. The means transformation frequencies were 3.6 x 10-6cells, 4.9 x 10-6 cells & 4.2 x le cells for S.typhi, S. paratyphi A & S. paraophi B respectively. Endonuclease digestion of plasmid and transconjugant produced the same digestion pattern. Conclusion, multidrug resistance strains of S.typhi, S.paratyphi A and S.paraophi B have been established and have persisted in the bacterial population. Furthermore, through the acquistion of a plasmid confering multidrug resistance, this strain has been able to adapt to and survive the challenge of antibiotics. Also, the organism acts as a pool for resistance plasmids which may be transferred to other pathogenic organisms. |
