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

Abstract

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 Salmonella strains are essential for minimizing human infection. This study aimed to identify Salmonella 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 Salmonella 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 Salmonella spp. isolates with the agar disk diffusion method (Kirby–Bauer technique). Multi-antibiotic resistance index and antibiotic resistance index (ARI)for Salmonella enterica isolates were calculated. Results: Twenty-one of 131 samples (16%) were positive for Salmonella 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 Salmonella spp. contamination. Only 9 of 21 (42.8%) isolates were confirmed as S. enterica 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 Salmonella 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 Salmonella 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 Salmonella, one of the most important foodborne microorganisms that cause food poisoning.

Pathogenic Bacteria and Their Antibiotic Resistance Patterns in Milk, Yoghurt and Milk Contact Surfaces in Debre Berhan Town, Ethiopia

“…Of the 80 bacteria isolated, 52/80 (65.0%) were MDRs and 20/49 (40.8%) isolates were confirmed as ESBL producers. Previous studies conducted in different parts of the world reported increased levels of MDR 5,[55][56][57][58][59][60][61][62][63][64] and ESBL-producing bacteria. [65][66][67][68][69] The higher levels of resistance observed in this study may be due to inappropriate antibiotic use on dairy farms.…”

Antimicrobial susceptibility profile of Klebsiella pneumoniae isolated from some dairy products in Libya as a foodborne pathogen

“…E. coli, Cronobacter spp., and Salmonella enterica have previously been reported by Garbaj et al [15], Garbaj et al [16] and Garbaj et al [17] as foodborne pathogens associated with dairy products in Libya. Data on the microbiological quality of Libyan dairy products related to K. pneumoniae are lacking.…”

“…[ 15 ], Garbaj et al . [ 16 ] and Garbaj et al . [ 17 ] as foodborne pathogens associated with dairy products in Libya.…”

Review on Antimicrobial Resistance Pattern of Similar Antibiotics Used for Escherichia coli and Salmonella spp. in Bangladesh with Public Health Significance

“…Abbassi et al [76] showed 57% amoxicillin resistance to E. coli in livestock in Tunisia, whereas 95% was found in diarrheal calves in Chile [77]. On the other hand, Garbaj et al [78] found 100% Salmonella-resistant amoxicillin in dairy products in Libya. Fig.…”