[Detection of Salmonella, Listeria and resistant bacteria to third generation cephalosporins in the Akkawi cheese in Northern Lebanon]

ABSTRACT

The detection and limitation of microorganisms that cause disease are important parts of food microbiology. Cheese and dairy products can serve as vehicles for transmission of infectious diseases. This study aims firstly to examine the presence of two important bacteria in food microbiology, Salmonella spp and Listeria monocytogenes by the immunological technique mini-VIDAS and secondly to isolate the multi drug-resistant bacteria using a medium supplemented by a third-generation cephalosporin. Fifty samples of Akkawi cheese randomly selected from the region of north Lebanon were tested. The screening for Listeria monocytogenes and Salmonella spp by the mini-VIDAS technique gave five positive results for Listeria monocytogenes and two positive results for Salmonella spp. The confirmation by biochemical identification showed that among the 5 mini-VIDAS positive results for Listeria monocytogenes, one isolate was identified as Listeria grayi, one as Aerococcus viridans, one as Streptococcus uberis, one as Brevibacterium spp and one as CDC group 1. The two positive mini-VIDAS Salmonella spp were identified as Salmonella group 1 and Enterobacter cloacae. The search for bacteria resistant to antibiotics has shown that out of the 50 samples analyzed, 21 samples contained Gram negative bacilli resistant to beta-lactam antibiotics [42%]. Results showed the presence of 11 isolates belonging to the family of Enterobacteriaceae and 15 non-enteric bacteria isolates. The antibiotic susceptibility profiles have demonstrated that in the group of Enterobacteriaceae, six isolates were ESBL [extended spectrum beta-lactamase] producers [3 E. coli, 2 Klebsiella pneumoniae and 1 Rhanella aquatilis] and 3 were cephalosporinase hyper-producing isolates [Enterobacter cloacae, Serratia odorifera and Hafnia alvei]. Regarding the non-enteric bacteria, one notes the presence of 8 strains of Acinetobacter calcoaticus, 3 Burkholderia cepacia, 2 Pseudomonas aeruginosa, 1 Sphingomonas paucimobilis and 1 Stenotrophomonas maltophiliae. Results on the presence of bacteria resistant to antibiotics in the analyzed cheese samples indicate a real problem for public health and should draw attention to the need to implement adequate control systems in this country.