Gram positive rod shaped, non-spore former Listeria monocytogenes is the major food-borne pathogens for humans and animals. It can cause serious foodborne infection. The bacterium is saprophyte and can grow on wide range of temperature (0-45°C). Due to this it contaminates different food products. Consumption of this contaminated food products can cause serious problems in neonates, pregnant women and immunocompromised peoples. Its signs may develop between day one to three months after ingestion of the organism. The neonates can develop septicemia, respiratory diseases and meningitis. The pregnant woman may develop influenza like symptoms, or keep an asymptomatic infection that ends in abortion, premature birth or sepsis in the newborn. Healthy people hardly develop clinical signs but a febrile gastroenteritis syndrome has been reported. No doubt this disease is associated with unhygienic food consumption and is characterized by fever, nausea, diarrhea, headache, abdominal pain and sometime myalgia. These symptoms may be resolved in one to three days Listeria monocytogenes was isolated by conventional methods and suspected colonies were identified by Gram staining and biochemical tests catalase and oxidase test. The DNA was extracted from isolated colonies by 10% chelex method. The isolated strains were confirmed through PCR by targeting prfA gene of 479bp. Antibiotic resistance were also checked for confirmed isolates. A total of 160 (Fish meat n=80, Broiler meat n=80) samples were taken for the present study for screening Listeria monocytogenes. The bacterium was found in 19/80 (23.75%) samples of Fish and 5/80 (6.25%) of broiler meat samples through PCR detection.
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Later the confirmed isolates were tested to check the resistance profile of the bacterium to different commonly available antibiotics. For this 24hrs old culture were used. Three to five colonies were picked by sterile loop and transfer to test tube containing 10ml normal saline. To check the turbidity the tube was compared with 0.5 Macfarland standard. Then by sterile cotton swab the bacterium was spread on Mueller Hinton agar. Antibiotics were placed by sterile forceps on agar. The plates were incubated at 37°C for 24hrs. Zones of inhibition were measured in mm by the help of ruler and then compared with staphlycoccus aureus break points in CLSI. The susceptibility result shows that the bacterium was resistant to gentamicin. Mostly L. monocytogenes isolates were susceptible to antibiotics used in this study. This study suggested ampicillin as drug of choice for treatment of listeriosis. Preventive measures should be adopted to avoid the risk of the disease.