Multidrug-resistant Salmonella isolates from swine in the Eastern Cape Province, South Africa

Chinwe Juliana Iwu*, Benson Chucks Iweriebor, Larry Chikwelu Obi, Albertus Kotze Basson, Anthony Ifeanyi Okoh

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)


Copyright ©, International Association for Food Protection. The exposure of farm animals to antimicrobials for treatment, prophylaxis, or growth promotion can select for resistant bacteria that can be transmitted to humans, and Salmonella as an important zoonotic pathogen can act as a potential reservoir of antimicrobial resistance determinants. We assessed the antibiogram profiles of Salmonella species isolated from pig herds in two commercial farms in South Africa. Two hundred fifty-eight presumptive Salmonella isolates were recovered from the fecal samples of 500 adult pigs. Specific primers targeting Salmonella serogroups A, B, C1, C2, and D were used to determine the prevalence of different serogroups. Only serogroup A (n = 48) was detected, while others were not. Antimicrobial susceptibility of the confirmed Salmonella serogroup A isolates was performed by using the disk diffusion method against a panel of 18 antibiotics. All the 48 isolates were resistant to tetracycline and oxytetracycline, while 75% were resistant to ampicillin, sulphamethoxazole-trimethoprim, nalidixic acid, and streptomycin. All the isolates exhibited multidrug resistance, with the predominant phenotype being against 11 antibiotics, and multiple antibiotic resistance index ranged between 0.3 and 0.6. The incidence of genes encoding resistance against ampicillin (ampC), tetracycline (tetA), and streptomycin (strA) were 54, 61, and 44%, respectively. We conclude that healthy pigs are potential reservoirs of multidrug-resistant Salmonella that could be transmitted to humans through the food chain and, hence, a significant public health threat.
Original languageEnglish
Pages (from-to)1234-1239
Number of pages6
JournalJournal of Food Protection
Issue number7
Publication statusPublished - 1 Jul 2016
Externally publishedYes


  • Antimicrobial resistance
  • Salmonella
  • Serogroup
  • South Africa
  • Swine


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