Enterotoxigenicity of Staphylococcus aureus isolated from traditional and commercial dairy products marketed in Iran

Abstract

This study was conducted to determine the prevalence rate, enterotoxigenecity, and antimicrobial resistance of S. aureus isolated from dairy products in Iran. From September 2010 to July 2011, a total of 347 samples from various dairy products, traditional and commercial, were collected from randomly selected retail stores. Overall, 20 samples (5.8%) were found to be contaminated with S. aureus. The highest prevalence of S. aureus was found in traditional cheese (11.1%), followed by traditional ice-cream (5.9%), cream (5.6%), and butter (5.3%). The ability to synthesize classical staphylococcal enterotoxins (SEA-E) was determined in 7 of 20 (35%) isolates by using ELISA. SE type C was the most common enterotoxin found in the isolated S. aureus (42.9%), followed by SE type A (28.6%), SEA+SEC and SE type D (14.3%). Of the 20 isolates, 16 (80.0%) were positive for one or more entrotoxin genes and 8 different genotypes were observed. Susceptibilities of the isolates were determined for 14 antimicrobial drugs using the disk diffusion assay. Most of the isolates (95.0%) were resistant to one or more two antimicrobial agent and 45.0% of the isolates were resistant to three or more of drugs. Resistance to ampicillin was the most common finding (55.0%), followed by tetracycline (40.0%) and penicillin G (30.0%). The results of this study showed the wide spread of enterotoxigenic and multidrug-resistant S. aureus strains in traditional dairy products in Iran and highlighted their public health hazards.

Effect of microbial sanitizers for reducing biofilm formation of Staphylococcus aureus and Pseudomonas aeruginosa on stainless steel by cultivation with UHT milk

“…Planktonic bacterial could attach new area on stainless steel surface returning to first step of cycles to proliferate the cell monomer before development to mature stage again. Biofilms of P. aeruginosa and S. aureus were formed from individual planktonic cells in a complex and presumably highly regulated developmental process with various signals, including the nutritional status of the environment (O’Toole and Kolter, 1998; Pratt and Kolter, 1998; Rahimi, 2013). S. aureus strains were known to be frequently resistant to antibiotic treatment due to their capacity to produce an EPS barrier and because of their location within microabscesses, which limit the action of drugs and sanitizing reagents (Lund and Ormerod, 1995).…”

Prevalence, characterization, and control of S. aureus isolated from raw milk and Egyptian soft cheese

“…In previous studies, it was mentioned that there is a possibility of toxin secretion from S. aureus if the bacterial count exceeds 10 3 CFU/ml or g (Zeinhom et al, 2015). The high incidence in raw milk could be attributed to environmental pollution, cross-contamination between the milk and each other and poor handling during transportation or in milk collection centers, besides, shedding of S. aureus from infected animals is another cause of contamination of milk and dairy food (Addis et al, 2011;Rahimi, 2013). Talaga cheese was prepared from pasteurized milk;…”

Análise microbiológica e teor de Nitrito e Nitrato em queijos

“…Rahimi [25], estudando a enterotoxicidade de Staphylococcus aureus em produtos lácteos comerciais, encontrou 11,1% das amostras de queijos positivas para esse patógeno, possivelmente pelo uso de leite não pasteurizado, além da produção de alimentos em locais insalubres sem cuidados de manipulação e armazenamento [26]. Em relação ao Staphylococcus coagulase positiva, encontrou-se 25% dos queijos analisados em desacordo com a legislação, corroborando com o estudo de Pinto et al [27], no município de Santa Helena (PR), com amostras de queijos tipo minas frescal inspecionadas pelo serviço Estadual e Federal.…”