Microbial Quality of Regularly Consumed Imported and Local Bulgarian Cheeses of Upper Price Segment

The rich nutritional content of cheese favors the development both of beneficial and food-borne pathogenic microorganisms. The study aimed to evaluate the microbial quality of seven cheeses, imported and Bulgarian, and to screen for antimicrobial resistance of isolated pathogenic microorganisms. The total number of bacteria, fecal enterococci, staphylococci, Clostridium perfringens, E. coli, yeasts, and molds were assessed according to ISO standards and EC № 1441 using selective and differential chromogenic media. Randomly picked isolates were sub-cultured on corresponding media. Identification of isolates was carried out using the Crystal Gram-positives system, catalase, PYR-test, and API 20 C AUX Candida. Antimicrobial resistance screening was carried out according to EUCAST-2023, The European Committee on Antimicrobial Susceptibility Testing. All cheese samples except one contain bacteria, yeast, and molds under the permissible standard limits. Isolated bacteria were identified as pathogenic Enterococcus durans, two strains of Enterococcus faecalis, Staphylococcus simulans. Isolated yeasts belong also to pathogenic Candida krusei – four strains, and Candida glabrata. Only one strain – E. faecalis-2 showed resistance to three antibiotics while E. faecalis-1, E. durans, S. simulans, C. krusei, and C. glabrata were susceptible to all tested antimicrobials. The studied cheeses are safe for consumption except one.