RESUMO
Several hundred strains of S. typhi isolates from typhoid patients admitted to different fever hospitals in Cairo, Kaluobiya and Sharkiya governorates during the period from June, 1991 to May, 1992 were studied. The strains were tested for susceptibility to the 3 antimicrobials of choice for typhoid treatment namely chloramphenicol [CM], ampicillin [AP] and trimethoprim - sulphamethoxazole [SXT]. 28 strains were found resistant to one or more of these drugs. Seven were resistant to CM, 22 to AP and 27 to SXT. Out of the 7 strains resistant to CM, 4 were resistant to the 3 drugs, one resistant to CM and AP, 2 resistant to CM and SXT. Plasmid profile analysis of resistant and sensitive strains showed that a specific band at 3. 8 Kbp is characterized in strains resistant to the 3 antimicrobials. Other strains had no such a plasmid band. Another plasmid with a molecular size over 9 kbp was present in both phenotypes. Additional studies are ongoing in our institute for further identification and characterization of resistant strains. In addition, plasmid profile analysis of resistant S. typhi strains are undertaken aiming at using this analysis as a routine test for antimicrobial resistance identification