Detection of Multi-drug Resistant Non-typhoid Salmonella Isolates in Cases of Gastroenteritis in Egypt

Aims: The current study aimed to determine the prevalence and multidrug resistance of non-typhoid Salmonella in patients with gastroenteritis at Minia, Egypt. The presence of tetB gene and cat gene was determined by PCR to have a clue of the resistance mechanisms to tetracycline and chloramphenicol as available and cheap drugs in treatment of non-typhoid Salmonella infections in developing countries.
Methodology: Five hundred stool samples were collected from patients with gastroenteritis, attending Minia Fever Hospital, Egypt, in the period from August 2011 to January 2014, all the participants showed negative- Widal test that was necessary to be included in the study. The stool samples were examined by standard microbiological, biochemical, invA gene amplification by PCR and serological tests to isolate non-typhoid Salmonella. The antimicrobial susceptibility was tested by the disc diffusion method using a panel of 11 discs of different antimicrobial groups, the Production of extended-spectrum β-lactamase was detected using the double disk synergy test. The presence of tetB gene and cat gene was determined by PCR in tetracycline and chloramphenicol resistant isolates respectively.
Results: Of 500 samples, 4.4% (22/500) were non-typhoid Salmonella. Most of isolates were resistant to; ampicillin 86.4% (19/22) then tetracycline and trimethoprim-sulphamethoxazole 77.3% each (17/22), 27.3% of isolates (6/22) were resistance to chloramphenicol. However low percentage of isolates were resistant to quinolones and most of isolates (95.5%) were sensitive to amikacin and ciprofloxacin. 18% (4/22) of isolates were ESBL producers and 81.8% (18/22) were multiple drug resistant (MDR). tetB and cat genes were detected in 64.7% (11/17) and 50% (3/6) of isolates resistant to tetracycline and chloramphenicol respectively.
Conclusion: This study revealed high prevalence of MDR non-typhoid Salmonella isolates that represents a serious health problem in the region under study. Quinolones remain the treatment of choice, while amikacin can be used in children. Continuous search for the mechanisms of resistance by molecular studies is important for effective management of NTS infections in Egypt.