Prevalence of Pseudomonas aeruginosa in Milk and Some Dairy Products with Reduction Trials by Some Natural Preservatives

Abstract

Contamination of milk and dairy products with spoilage and pathogenic microorganisms is a common problem worldwide. Therefore, this study was conducted on 200 samples (milk, Kareish cheese, Damietta cheese, and plain yoghurt, 50 of each) collected from Zagazig City, Sharkia, Egypt to be examined bacteriologically to isolate and identify the multi-drug resistant Pseudomonas aeruginosa as well as some reduction trials on cold stored soft cheese using some natural compounds including the essential oil (EO) of Clove (0.01%, 0.1%) and Nigella Sativa (NS 0.5%, 1%), in addition to Nisin (10 ppm 12.5 ppm). The obtained results revealed the pseudomonas aeruginosa prevalence in the examined milk and dairy product samples was 45(22.5%); 24(48%) from raw milk samples, 8(16%) from yoghurt, 9(18%) from soft cheese and 4(8%) from kareish cheese. The isolated Pseudomonas aeruginosa harbored some antibiotic-resistant genes including blaTEM, blaSHV, ermB, and Mcr1 genes, while blaOXA-1 failed to be detected, so it was resistant to different types of antimicrobial agents. The multiple antibiotic resistance index (MAR) of the isolated strains was 0.500. Clove (0.01%, 0.1%) and Nigella Sativa (NS 0.5%, 1%), in addition to Nisin (10 ppm, 12.5 ppm) had an antibacterial effect against Pseudomonas aeruginosa compared with control samples and acted as good preservatives that extended the storage period and shelf life of soft cheese up to thirty days.