Prevalence, Antimicrobial Resistance and Serotype Distribution of Listeria monocytogenes Isolated from Raw Milk and Dairy Products

Kevenk T. O., Terzi Gülel G.

JOURNAL OF FOOD SAFETY, vol.36, no.1, pp.11-18, 2016 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 36 Issue: 1
  • Publication Date: 2016
  • Doi Number: 10.1111/jfs.12208
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.11-18
  • Ondokuz Mayıs University Affiliated: Yes


The objectives of study were to assess presence of Listeria monocytogenes, perform serotyping and investigate antibiotic resistance in raw milk and dairy products. A total of 210 milk and dairy products including white (n=20) and kashar cheese (n=20), ice cream (n=20), butter (n=20), cokelek (n=10), kuymak (n=10) and farm cheese (n=10) were obtained from Samsun, Turkey. All samples were analyzed using an immunomagnetic separation-based culture technique and strains of L.monocytogenes were confirmed by presence of hlyA and iap genes by polymerase chain reaction (PCR). L.monocytogenes was identified in 5 of 100 (5%) milk samples, serotyped as 4b and 1/2b, and in 9 of 110 (8.2%) dairy products, serotyped as 1/2a, 1/2b and 1/2c. However, L.monocytogenes was not identified from butter, kashar and ice cream samples. The antibiotic susceptibility against ampicillin, amoxicillin/clavulanic acid, erythromycin, chloramphenicol, penicillin G, oxytetracycline, tetracycline and vancomycin was assessed by disc diffusion method. It was found that 15.3% of isolates were resistant to at least one drug and 36.5% were multidrug resistant. Among isolates, resistance to tetracycline was most commonly encountered (34.6%), followed by resistance to chloramphenicol (25%) and penicillin G (23%). In conclusion, our data also indicate that consuming raw and unpasteurised milk and dairy products could pose a risk of listeriosis in humans.