Detection of Staphylococcus aureus enterotoxigenic strains in bovine raw milk by reversed passive latex agglutination and multiplex polymerase chain reaction

Abstract

Aim:This review gives an outline of the assessment of enterotoxigenic Staphylococcus aureus tainting levels in raw milk from different sources in Egypt and characterization of enterotoxigenic strains utilizing a technique in light of PCR to identify genes coding for the production of staphylococcal enterotoxin (SE). The obtained data were compared with results from the application of the reversed passive latex.Materials and Methods:Multiplex PCR and reversed passive latex agglutination (RPLA) were used. A total of 141 samples of raw milk (cow’s milk=33, buffalo’s milk=58, and bulk tank milk=50) were investigated for S. aureus contamination and tested for enterotoxin genes presence and toxin production.Results:S. aureus was detected in 23 (16.3%) samples phenotypically and genotypically by amplification of nuc gene. The S. aureus isolates were investigated for SEs genes (sea to see) by multiplex PCR and the toxin production by these isolates was screened by RPLA. SEs genes were detected in six isolates (26.1%) molecularly; see was the most observed gene where detected in all isolates, two isolates harbored seb, and two isolates harbored sec. According to RPLA, three isolates produced SEB and SEC.Conclusion:The study revealed the widespread of S. aureus strains caring genes coding for toxins. The real significance of the presence of these strains or its toxins in raw milk and their possible impact a potential hazard for staphylococcal food poisoning by raw milk consumption. Therefore, detection of enterotoxigenic S. aureus strains in raw milk is necessary for consumer safety.

Detection of Enterotoxigenic Staphylococcus aureus Strains in Raw Milk of Cows Reared in Erbil Province/Iraq

“…In the present study, the overall presence of the pathogen was 30.6% among samples screened by PCR and microbiological methods,with the higher proportion of S. aureus (42.6%) in BTM than in DM (18.6%). Our results are matched with other researchers who found a S. aureus prevalence of 24% to 44% in cow's milk (Mansour et al, 2017, Khudor, 2012, Ronco et al, 2018, Peles et al, 2007, Akindolire et al, 2015.Ben Said et al…”

Staphylococcus aureus Exotoxins and Their Detection in the Dairy Industry and Mastitis

“…S. aureus strains associated with bovine mastitis harbor a variety of staphylococcal SAg toxin genes; these are normally acquired by horizontal gene transfer via genetic mobile elements or bacteriophages, and even by bacterial mating. Some studies have determined the relationship between SAg toxin genes, genotypes, and pathogenic properties of S. aureus isolates, by methods such as randomly amplified polymorphic DNA (RAPD) [ 2 ], pulsed-field gel electrophoresis (PFGE), reversed passive latex agglutination (RPLA), and PCR [ 25 , 26 , 27 , 28 , 29 ]. Staphylococcal enterotoxins G to Q (SEG–SeEQ) are the most frequently found in S. aureus strains isolated from bovine mastitis; these enterotoxins are involved in the mammary inflammatory present in the animals.…”

Prevalence and distribution of resistance and enterotoxins/enterotoxin-like genes in different clinical isolates of coagulase-negative Staphylococcus

“…In addition to classical SEs, 16 new types of SEs (SEG, SEH, SEI, SER, SES, SET) and SEls (SElJ, SElK, SElL, SElM, SElN, SElO, SElP, SElQ, SElU and SElV) have been reported [6]. SEs are extracellular protein toxins with low molecular weight (26.900 -29.600 KD) [8,9]. They are heat resistant and retain their biological activity after treatment with majority of proteolytic enzymes [10].…”