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Antibiotic-free pig production does not guarantee higher levels of consumer protection

Raleigh (aho/lme) – In the lay press, an association is commonly made between the use of antibiotics in pigs and the occurrence of antibiotic-resistant Salmonella in both live animals and pigmeat.  But according to sci­entists at North Carolina State University, this view may not be entirely correct.  In a study recently published in the Journal of Food Protection, they compared the prevalence and antibiotic resistance of Salmonella from conventional and “antibiotic-free” production systems.  A total of 889 pigs and 743 carcasses were sampled in the study.
Salmonella prevalence was found to be significantly higher in pigs and carcasses from antibiotic-free syst-ems (15.2%) than from conventional systems (4.2%).
Antibiotic resistance was detected against 10 of the 12 antibiotics tested.  Resistance was most commonly found against tetracycline (80%), streptomycin (43.4%) and sulfamethoxazole (36%).  Frequency of resist­ance to all these antibiotics (except tetracycline) was higher among conventional farms.
A total of 28 resistance patterns were detected.  A resistance pattern with streptomycin, sulfamethoxazole and tetracycline was the most common; the proportion of isolates with this pattern was virtually identical in the two types of production system (19.5%).
A pentaresistance pattern with ampicillin, chloramphenicol, streptomycin, sulfamethoxazole and tetracycline was strongly associated with antibiotic-free systems.  Multidrug resistances of this type can make it more di­fficult to treat Salmonella infections in humans.
The study shows there is no justification for the commonly-held view that antibiotic-free production is asso­ciated with a lower prevalence of Salmonella and less antibiotic resistance.  Multidrug-resistant Salmonella can occur in antibiotic-free production systems as well, sometimes more often than in conventional systems.

Gebreyes WA, Thakur S, Morrow WEM. Comparison of prevalence, antimicrobial resistance, and occurrence of multidrug-resistant Salmonella in antimicrobial-free and conventional pig production. J Food Prot 2006; 69 (4): 743-8

MET: 2018-07-17 07:11:48