31. Prevalence, molecular characterization and antibiogram study of Listeria monocytogenes isolated from raw milk and milk products

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Nishat Zafar Zeeshan Nawaz, Sidra Anam, Rabia Kanwar Ashiq Ali Muhammad Mudassar Muhammad Tariq Javid, Abdullah Zafar , Asima Tariq


Foodborne diseases are the primary cause of infections and mortality, especially in developing countries like Pakistan. Listeria monocytogenes is an emerging foodborne infection and a public health threat globally. The present study was designed to detect the prevalence and antimicrobial susceptibility pattern of Listeria monocytogenes in raw milk and milk products. A total of (n= 90) samples were collected from different dairy shops of Faisalabad comprising of 40 raw milk, 25 cheese, and 25 yoghurt samples. The samples were collected in sterile plastic bags and shifted to the laboratory in an icebox. The isolation and identification of Listeria monocytogenes was made by standard microbiological and biochemical procedures, while confirmation was done by polymerase chain reaction (PCR) by amplifying the hlyA gene. Antibiotic susceptibility profiling was performed by Kirby Bauer disk diffusion method. The results of the present study showed that among the total 90 samples, 24 (26.66%) were detected positive for L. monocytogenes with the highest prevalence in raw milk (16) followed by cheese (05) and yoghurt (03).  The highest resistance was observed for Penicillin (63.15%) among the isolates followed by Clindamycin (57.89%), Ciprofloxacin (26.31%) and Rifampicin (26.31%) while 100% isolates were found susceptible to Ampicillin, Cephalothin, Chloramphenicol, and Vancomycin. It is concluded that the frequency of Listeria monocytogenes is at an increasing trend in our dairy products, and stringent screening in transportation, processing and storage of dairy products should be needed to reduce the burden of L. monocytogenes infections.

Keywords: Antibiogram; Listeria monocytogenes; Prevalence; Raw milk



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