Abstract
The genus Salmonella consists of more than 2570 antigenic types. Salmonella Paratyphi A, B, C and Salmonella typhi are known to be non-lactose fermenters and the cause of typhoid fever.
The present study aimed to implement molecular (polymerase chain reaction PCR) and routine bacteriological methods to identify 5 Salmonella isolates; 3 clinical and 2 foodborne isolates (obtained from poultry) in Mosul city. Primary biochemical reactions indicated a tentative identification of the bacteria as Salmonella spp. All isolates were identified using selective media (MacConkey, Salmonella-Shigella and XLD agar) in addition to gram stain, and the biochemical tests (Oxidase, Indole, Urease, Citrate utilization, and Triple Sugar Iron agar reaction).
Identification was confirmed using molecular genome with PCR. DNA was extracted directly from each sample and amplified using Salmonella- specific primers.
We hereby report an unusual case of two unusual lactose fermenting strains of Salmonella, one clinical and the others from a poultry sampling. Lactose fermenting Salmonellae cultured on MacConkey agar appeared as pink colonies following a 24 hrs. incubation period at 37 ° C. Prolonged incubation (i.e. 48 hrs.) resulted in the appearance of transparent colonies. There were no former reports, as far as we know on such lac+ Salmonella strains in Mosul city.
Isolation of lactose fermenting Salmonellae is critically vital because it could be overlooked or misdiagnosed. Therefore, there is a need of awareness of such unusual Salmonellae that may be misidentified as other members of Enterobacteriaceae (Escherichia coli).
Identification of Salmonellae by Molecular PCR has proved to be a more convenient method that could be completed within 24-36 hrs. as compared to 3-8 days by routine bacteriologic methods.
