Isolation and Antimicrobial Resistance in Salmonella paratyphi B

Abstract

This study was carried out in Khartoum state during the period from November 2008 to March 2009, to isolate Salmonella paratyphi B from different clinical specimens and to determine antimicrobial resistance of the isolates. Three hundred and eight stool specimens were collected from patients suspected to have typhoid fever. The specimens were cultured on salnite F, then sub cultured on selective culture medium XLD for primary isolation of pathogen. Identification of the isolates was done by colonal morphology, Gram stain, biochemical tests using ABI 20 E, oxidase test and further the isolates were serotyped with specific antisera. The modified Kirby-Bauer disc diffusion method was adopted to evaluate the resistance rate of S.paratyphi B to antimicrobial agents. Minimum Inhibitory Concentrations of Ciprofloxacine, Cholormphinicol, Gentamicine, Ceftazidime and Tetracycline were determined by E.test. Out of three hundred and eight stool specimens investigated, only 8 (2.6%) S.paratyphi B isolates were isolated. Five of them were isolated from males and three were isolated from females. The results revealed that the antimicrobial resistance profile of S.paratyphi B was as follows: Tetracycline (12.5 %), Ciprofloxacin (12.5%), Ceftazidime (100%), Cholormphinicol (0 %), and Gentamicine (0 %). The results indicated that the MIC, MIC50 and MIC90 of Tetracycline were (0.25 to 5 μg/ml, 1 μg/ml and 1 μg/ml), Chloramphenicol (1.00 to 5 μg/ml, 1 μg/ml and 1 μg/ml( , Ciprofloxacin (0.004 to 0.01 μg/ml, 0.004 μg/ml and 0.004 μg/ml) and Gentamicine (1.00 to 5 μg/ml, 1 μg/ml and 1 μg/ml). The study concluded that the paratyphoid fever caused by S. paratyphi B is a common disease and slightly increased in the community, also the resistance to traditionally used antibiotics was partially increased. Continued surveillance for paratyphoid fever will help guide, future prevention and treatment recommendations.