Biochemical Characterization and Antimicrobial Susceptibility Test of the Bacterial Strain Isolated from Sandwich in Rajshahi University, Bangladesh

Abstract

This study was conducted to isolate and observe the morphological and biochemical characteristics of bacterial strains present in the sandwich. A single bacterial colony was isolated from a sandwich collected from different restaurants located in the area of the University of Rajshahi by plating from the diluted primary bacterial suspension of the liquid medium onto an agar solidified mineral salt medium after purifying through filter paper. The isolated bacterium was found to be Gram-positive, coccus, motile, lactose-non-fermenting, and could utilize different carbohydrates. Bacterial strain A showed a positive result for the Methyl Red test, the Catalase test, the Indole test, and the Simmons citrate agar test. The optimum culture condition of the isolate was pH 8 and the salt concentration was 0.1 gm/100 ml. The Minimum Inhibitory Concentration (MIC) value against Vancomycin was 50mg/ml and the viable cell count indicated 459×107 CFU/ml. The result showed that the isolated bacterial strain A was resistant to Vancomycin and amoxicillin, whereas it was susceptible to gentamycin, ciprofloxacin, and chloramphenicol. This bacterial strain A can grow to a harmful extent after a certain time of incubation, which may cause a health hazard.