Occurrence and antibiogram of multidrug-resistant isolated from dairy products in Libya.

BACKGROUND AND AIM

Foodborne illnesses are a serious challenge to human health and the economic sector. For example, salmonellosis remains a burden in developed and developing nations. Rapid and reliable molecular methods to identify strains are essential for minimizing human infection. This study aimed to identify spp. in raw milk and dairy products using conventional and molecular techniques and to test the antibiotic susceptibility of the isolated strains.

MATERIALS AND METHODS

One hundred and thirty-one milk and dairy product samples were randomly collected from different localities in Libya. Samples were examined for the presence of by conventional culture techniques, including cultivation in Rappaport-Vassiliadis broth and streaking on xylose lysine deoxycholate agar. Identification also used polymerase chain reaction and partial sequencing of 16S rDNA. Twenty-four antibiotics were used for the examination of antimicrobial resistance of spp. isolates with the agar disk diffusion method (Kirby-Bauer technique). Multi-antibiotic resistance index and antibiotic resistance index (ARI)for isolates were calculated.

RESULTS

Twenty-one of 131 samples (16%) were positive for spp. recovered from 9 (16%), 2 (11%), 4 (22.2%), and 6 (46%) samples of raw cow milk, fermented raw milk, and fresh locally made soft cheeses, Maasora and Ricotta), respectively. Samples of ice cream, milk powder, and infant formula showed no spp. contamination. Only 9 of 21 (42.8%) isolates were confirmed as . by partial sequence 16S rDNA analysis. All isolates were resistant to amoxycillin, bacitracin, penicillin G, lincomycin, vancomycin, clindamycin, and cloxacillin with an ARI of 0.042. In contrast, all tested strains were sensitive to levofloxacin, doxycycline, and ciprofloxacin. In addition, all of the tested isolates (100%) were resistant to more than one antibiotic.

CONCLUSION

This study demonstrated the applicability of molecular techniques, compared with conventional methods, as preferable for the identification of in milk and dairy products and thus reduction of milk-borne transmission to the consumers. From the view of public health, isolation and identification of multidrug-resistant strains from raw cow`s milk and locally prepared dairy products sold in the Libyan markets indicate the need to improve the handling and processing of milk and dairy products to minimize the prevalence of , one of the most important foodborne microorganisms that cause food poisoning.