Tarek El-Said El-Banna, Fatma Ibrahim Sonbol, Maysaa El-Sayed Zaki and Heba Hassan Ibrahim El-Sayyad
Listeria monocytogenes (L monocytogenes) is a gram-positive bacterium with public health problem. A total of 870 samples were collected. These include of 470 clinical samples from ascites of end stage liver disease and gastric lavages of diseased infants (0.8-2 month old) as well as of 400 environmental samples taken from the market such as lettuce, carrot, ice cream, soft cheese, frozen meat, liver and hamburgers. They are collected during March 2010 and December 2014, from Dakahlea Governorate, Egypt. Listeria cultures were carried out, isolated, and investigated. Listeria colonies were recovered only in 50 (26 from patients and 24 from environmental) out of 870 samples and assessed by biochemical tests. Antibiotic susceptibility of L. monocytogenes to different 17 antibiotics was carried out. The Listeria isolates were appeared susceptible to amoxicillin/ clavulanate and cotrimoxazole and showed different resistance levels of chloramphenicol, ampicillin, streptomycin and tetracycline and were completely resistant to cefipime and ceftazidime. Using the iodometric overlay method of 50 Listeria isolates, 32 (64%) were blactamase( s) producers. Following PCR assessment of antimicrobial resistance genes, 28/50 L. monocytogenes isolates contained more one antimicrobial resistance gene sequence. A high frequency of penA (46%) was detected compared to strA (38%), tetM (20%), and ampC (18%). The authors finally concluded that although L. monocytogenes was detected in environmental and clinical samples at low rates, it exerted pathological symptoms and are susceptible to amoxicillin/ clavulanate and cotrimoxazole with a high frequency of antimicrobial resistant penA gene.