Marija Ratkova

Sensitivity of 26 Listeria monocytogenes isolates toward 18 antimicrobial substances used in veterinary and human medicine was examined using the automated VITEK 2 Compact system bioMerieux. The obtained results indicate that L. monocytogenes strains isolated from food and food processing environment had resistance to several or more antimicrobial substances that are commonly used in the treatment in animals and humans. Results showed resistance of all 26 (100%) isolates toward Benzylpenicilin, Ampicilin/Sublactam, Oxacillin, Imipenem and Fosfomycine. Also 7 of the isolates (26.9%) were resistant to Clindamiycin, 3 (11.5%) to Quinupristion/ Dalfopristin and 1 strain to Teicoplanin, Vancomycin, Tetracycline and Fusic acid, respectively.

This study investigated the microbiological quality of cakes and pastries sold directly to the consumers in Skopje, Macedonia. Sampling took place in 16 sampling points (bakeries, confectioneries) with total number of 70 samples being investigated. All the samples were tested for S. aureus, Enterobacteriaceae, aerobic colony count, E.coli, Salmonella spp. and Listeria monocytogenes. The samples were tested in the Food microbiology laboratory at the Faculty of veterinary medicine in Skopje using standard methods accredited by the Macedonian Institute for Accreditation. Results were interpreted according to the Guidelines for the Interpretation of Results of Microbiological Analysis of Some Ready-To-Eat Foods Placed on the Market (HPA, UK). After the analysis of the results the following data was obtained: S.aureus: 68.57% (n= 48) of the samples were satisfactory, 31.42% (n=22) were acceptable and 0.0% (n=0) were unsatisfactory; Enterobacteriaceae: 60.0% (n= 42) of the samples were sa...

The infl uence of three organic acid, (acetic, lactic and citric acid in diff erent concentrations) were evaluated over two major foodborne pathogens, Listeria monocytogenes and Salmonella enteritidis. For evaluation we used two diff erent laboratory designed models such as, agar gel diff usion test and broth reduction test. The results from agar gel diff usion tests revealed variation of the inhibition zone of Listeria monocytogenes and Salmonella enteritidis to three engaged organic acids in concentration 10%, 8%, 6%, 4%, 2%. The two tested organisms were most sensitive to lactic acid and slightly less sensitive to citric and acetic acid respectively. Listeria monocytogenes was more sensitive to all three tested organic acids compare to Salmonella enteritidis. Infl uence of above mentioned organic acids in buff ered peptone water broths revealed Listeria monocytogenes reduction in cell number by 4,6 log cfu/mL for 0.04% acetic acid and 3,1 and 2.8 log cfu/mL for lactic acid and ac...

The primary objective of our study was to detect the occurrence of enterotoxigenic Staphylococcus aureus in diverse types of cheese (cow's milk cheese and mixed milk cheese) samples from R.N. Macedonia. Cheese samples were analyzed for enumeration and isolation of the S. aureus strains according to ISO 6888-1. We detected the toxigenic potential of the strains by the use of the Enzyme Link Fluorescent Assay VIDAS system, and we confirmed the presence of the SEs (sea, seb, sec, sed, see) genes by multiplex PCR. The results showed that out of 270 samples of cheese, coagulase-positive staphylococci (CPS) were detected in 27 (10%), and coagulase-negative staphylococci in five samples (1.8%). Biochemically, all 27 CPS samples were confirmed to be Staphylococcus aureus. With VIDAS SET2 test we confirmed that 11 isolates are producers of one of the toxins limited by the test. With the conventional PCR we confirmed genes in only 7 isolates. Most common detected gene was seb n=3 (42.8%),...

Staphylococcus aureus is an important foodborne pathogen due to toxin-related virulence, invasiveness and antibiotic resistance. The ability of S. aureus strains to produce one or more staphylococcal enterotoxins (SEs) in food has been associated with the occurrence of staphylococcal food poisoning (SFP), which is the most common foodborne intoxication worldwide. The study aimed to determine the count of S. aureus strains in samples of raw cow’s milk and various cheeses produced in R. North Macedonia and to detect their ability to produce enterotoxins by passive agglutination SET RPLA (OXOID, UK) and by enzyme-linked fluorescence assay (ELFA) VIDAS SET 2 (Biomerieux, France). A total of 130 S. aureus strains were analyzed. The ability to produce SEs was determined in 17 (13.1%) strains using the SET RPLA detection kit and in 20 (15.4%) strains using the VIDAS SET 2. The study detected enterotoxigenic strains in cheese samples, despite the low count of S. aureus which was below the d...