Analysis of the results of the study on the presence of methicillin-resistant Staphylococcus (MRSA) in food products of animal origin

Abstract

The frequency of Staphylococcus aureus resistance to antibiotics (AB) has significant differences in different countries and geographical regions. The main problem is represented by strains of methicillin-resistant staphylococcus (MRSA), resistant to many ABs. Often, MRSA is transmitted to humans through animal food products. Purpose: investigate animal foods for S. aureus and detect methicillin-resistant strains. Food research was carried out according to ISO 6888-1, ISO 6888-2, MW 15.2-5.3-004:2007, State standard 10444.2. The material for further research was the isolates of S. aureus isolated from different groups of food products of animal origin. Disks containing methicillin (30 mg) and oxacillin (5 mg) and Müller-Hinton nutrient medium were used to determine the sensitivity to AB. The research was conducted by disc diffusion method in accordance with the Methodological Guidelines «Determination of microorganism sensitivity to antibacterial preparations» dated 12/25/2014. In addition, the data of the state veterinary report on the study of milk of cows and determination of antibiotic resistance of cultures isolated from it in 2017 were analyzed. A study on the presence of coagulase-positive Staphylococcus was carried out in food products of animal origin during 2016–2017. During this period, 58 isolates of S. aureus were identified, of which 7 were classified as MRSA, which was an average of 12.1 % of all isolated cultures. The highest amount of MRSA is isolated from chicken meat – 29.0% and meat products – 20.0%, ready-to-eat fish – 16.7% and meat mincer – 6.1%. The 2017 report on antibiotic resistance from all regions of Ukraine was also analyzed for the detection of S. aureus strains resistant to oxacillin. These data were available only for S. aureus isolated from milk from cows suffering from subclinical mastitis. Of the 47 strains of S. aureus, 22 (46.8%) were methicillin-resistant. MRSA poses a serious threat to the health of humans and animals and may be transmitted through food. There is no monitoring system in Ukraine on the detection of resistant strains in food products. A single list of ABs according to which laboratories conducted sensitivity tests was not approved. Therefore, in most cases, the sensitivity of Staphylococcus to oxacillin/methicillin is not determined. We found that, on average, MRSA from animal foods of animal origin in Ukraine is found in 12.1% of cases. Milk of animals, that suffer from subclinical forms of mastitis, can serve as a source of MRSA for humans, because it was detected in 46.8% of cases.