Presence and antimicrobial susceptibility of methicillin-resistant Staphylococcus aureus in raw and pasteurized milk and ice cream in Tabriz by culture and PCR techniques

Abstract

Reports of methicillin-resistant Staphylococcus aureus (MRSA) in food have become more frequent in recent years. The aim of this study was to estimate the presence of MRSA in raw milk, pasteurized milk and ice cream in Tabriz by culture and polymerase chain reaction (PCR) techniques, as well as the determination of their antimicrobial susceptibility. For this purpose, 300 samples of raw milk, pasteurized milk and ice cream were collected from different sellers in Tabriz. They were first evaluated for contamination by coagulase positive S. aureus through culturing method, and then the isolates were subjected to PCR method according to nuc gene in order to confirm S. aureus and methicillin resistance gene (mecA). Finally the antimicrobial resistance trend of the isolates was investigated by disc diffusion agar method. The cultured samples indicated that 50 (50%) of raw milk samples, 2 (2%) of pasteurized milk samples and 26 (26%) of ice cream samples were contaminated by S.aureus. Forty five, 1 and 23 of these isolates, respectively were confirmed to be S.aureus based on PCR using nuc gene primer. From the total of 69 isolates containing nuc gene, 20 isolates had the resistant mecA gene. Of the 69 isolates, 17 isolates showed simultaneous resistance against 4 antibiotics, 18 against 5 antibiotics, 8 against 6 antibiotics, 8 against 7 antibiotics, 7 against 8 antibiotics, 6 against 9 antibiotics, 2 against 10 antibiotics and 3 isolates against 11 antibiotics. In other words 100% of the isolates showed simultaneous resistance to more than 3 antibiotics. The results provide evidence that the presence of antimicrobial resistant strains of S. aureus has become remarkably widespread in food samples. This calls for better control of the sources of food contamination and as well as the spread of antimicrobial-resistance organisms.

The Prevalence and Antibiotic Resistance of Methicillin-Resistant Staphylococcus aureus (MRSA) in Milk and Dairy Products in Balikesir, Turkey

“…In accordance with our findings, Mirzaei et al (2011) did not detect the mecA gene in staphylocci isolated from 50 butter samples.…”

“…Kanaan and Al-Shammary (2013) found MRSA phenotypically in 6 (40%) of the 15 soft white raw cheese with whey samples. This study's results are similar to those of Arefi et al (2014) and higher than other researchers' results (Huber et al, 2010;Yücel and Anıl, 2011;Özpınar, 2011;Mirzaei et al, 2011;Can and Çelik, 2012;Kanaan and Al-Shammary, 2013). These differences may be due to variations in cheese-production technology, the number of samples, and the fact that the milk used in production was not pasteurized.…”

Prevalence of Methicillin-Resistant Staphylococcus aureus and Other Staphylococcus Species in Raw Meat Samples Intended for Human Consumption in Benin City, Nigeria: Implications for Public Health

“…The thermostable endonuclease gene ( nuc gene) encodes the expression of the thermostable endonuclease enzyme, known to be an important pathogenic factor for S. aureus. The presence of such a gene in the genome of the staphylococcal cell increases the organism’s inherent capacity to initiate infection [1,6]. …”

“…The penicillin binding protein 2a (PBP2a) has a reduced affinity for beta-lactam antibiotics, resulting in resistance to most beta-lactam antimicrobial agents. Therefore, mec A or PBP2a are indispensable targets for methicillin-resistant staphylococci detection [6,13]. …”

Παρουσία ανθεκτικών στη μεθικιλίνη Staphylococcus aureus σε γάλα και γαλακτοκομικά προϊόντα

“…In Iran, Mirzaei et al (2012) examined 300 samples (100 raw milk, 100 pasteurized milk and 100 ice cream) in 2010 and reported that 20 isolates (14 from raw milk, 6 from ice cream) carried the mecA gene, whereas Alian et al (2012) examined 348 raw milk samples from randomly selected herds between 2010 and 2011 and found a MRSA prevalence of 28%.…”