Bacteriological and Molecular studies of Listeria species in milk and milk products at El-Kaliobia Governorate

Abstract

A total of 200 random samples of raw milk, Fita cheese, Kariesh cheese and ice cream (50 samples each) were collected from small retails and different supermarkets in El-Kaliobia Governorate to estimate the prevalence of Listeria species in such products with special interest to L. monocytogenes. The bacteriological examination of the samples resulted; 13(6.5%) isolates of Listeria species were recovered from 200 samples, includes 10 L. monocytogenes (5.0%) and 3 L. grayi (1.5%). Moreover, the other 4 species (L. ivanovii; L. innocua; L. seeligeri and L. welshimeri) were not isolated from all samples (Listeria strains). The in-vitro antimicrobial sensitivity test showed that the isolated L. monocytogenes were sensitive to amoxicillin; gentamycin; enrofloxacin; kanamycin and ampicillin. While they were resistant to Nalidixic acid, streptomycin and tetracycline. The results of virulence tests for isolated Listeria strains appeared that all of L. monocytogenes strains were virulent strains as all of them were positive to CAMP test; showed narrow zone of β-hemolysis on sheep blood agar and were positive for Anton's test. Meanwhile, L. grayi strains were non-virulent, as none of them could produce hemolysin (CAMP test negative) and negative for Anton's test. The PCR results for L. monocytogenes showed that all genes (16S rRNA; inlA; inlB; hlyA and prfA) were detected in five studied strains (100.0%) i.e., all studied strains were L. monocytogenes and all of them were virulent strains.

Prevalence of Listeria Species in Dairy Cows and Pregnant Women with Reference to Virulotyping of Listeria monocytogenes in Egypt

“…On the contrary, lower prevalence of L. monocytogenes was detected in cow milk samples (2%) by Khedr et al [39] in Egypt, and (1.1%) by Almeida et al [40] in Portugal. However, higher prevalence of L. monocytogenes (8.3%) from cow milk samples was cited by El-Marnissi et al [41] in Morocco, and (6%) by Abd El-Tawab et al [42] in Egypt.…”

Incidence of Listeria Species in Some Dairy Products in Beni-Suef Governorate

“…Nearly similar results (19.04%) was reported by Shamloo et al (2015), while prevalence of Listeria spp. was much higher as compared to those observed by Wahba (2002); Rahimi et al (2012); Akya et al (2013); Muhammed et al (2013) andAbd El Tawab et al (2015). High incidence of Listeria spp.…”

“…The results of Talaga cheese in the present study are in agreement with the results of Atil et al (2011); Akya et al (2013) and Ahmed (2013). In the studies conducted by Kevenk and Gulel (2016);Abd El Tawab et al (2015); Wijendra et al (2014), L.monocytogenes was isolated with very low incidence of 1(5%), 1(2%) and 4(5%) in the examined white cheese samples.…”

“…Abd El Tawab et al (2015) detected that the (hlyA) gene was amplified in 5(100%) L.monocytogenes strains. Also Nayak et al (2015) detected virulence listeriolysin O(hlyA) gene in the all three L.monocytogenes which isolated from raw milk samples.…”

“…Milk and dairy products, because of their nutritional value, are suitable for development of microorganisms including pathogenic bacteria as Listeria species (Kasalica et al, 2011;El Marnissi et al, 2013 andAbd El Tawab et al, 2015).…”