Antimicrobial Drug Resistance and Plasmid Profiles of <i>Salmonella</i> Isolates from Humans and Foods of Animal Origin in Uganda

Abstract

Salmonella organisms are among the most common causes of human bacterial gastroenteritis worldwide, and food animals are important reservoirs of these bacteria. A further danger lies in the development of drug resistance in these organisms, primarily driven by non-prudent overuse of antiinfectives. The current study compared the plasmid profiles and drug susceptibility patterns of Salmonella isolates from man and foods of animal origin in Uganda. A total of 92 Salmonella isolates (58 from man and 34 from foods of animal origin) were analyzed. Identification was done by using biochemical tests; plasmid profiling by agarose gel electrophoresis while susceptibility testing to tetracycline, ampicillin, chloramphenicol, nalidixic acid, trimethoprim-sulphamethoxazole, ciprofloxacin, ceftriaxone and tetracycline were done by the Kirby Bauer Disc Diffusion method. Among the human isolates, 57/58 (98.3%, 95% CI, 91.8% -99.9%) were susceptible to Ciprofloxacin compared to 32/34 (94.1%, 95% CI, 81.9% -91%) of animal-derived isolates. On the other hand, 48/58 (82.7%, 95% CI, 71.4% -91%) human-derived isolates were resistant to Trimethoprim sulfamethoxazole compared to 29/34(85.3%) of the animal-derived isolates. Fifty four percent (n = 50) of the all the isolates were resistant to at least three antibiotics whereas only 2.2% (n = 2) were susceptible to all the seven drugs tested. Most worrying, however, was the fact that only 45% percent of the isolates were sensitive to all the three drugs (chloramphenicol, nalidixic acid and ciprofloxacin) commonly used in the treatment of salmonellosis in this setting. The risk of ampicillin resistance was three times more likely to occur in animal-derived as compared to human-derived isolates (Odds Ratio = 2.705, 95% CI, 1.3 -5.8) as was that to nalidixic acid (Odds Ratio = 2.895, 95% CI, 1.17 -7.2). Plasmid profile analysis showed eight clusters comprising of 68.7% (46/67) of the isolates. In five of the eight clusters, there were both animal and human-derived isolates. Resistant strains of Salmonella are common in this setting and meat/meat products are the commonest source of infection. A majority of the isolates are multi-drug resistant, and there is evidence of cross-species transmission of plasmids, and possibly drug resistance, between animals and humans.

Serotypes and antimicrobial resistance patterns of <em>Salmonella enterica</em> subsp. <em>enterica</em> in pork and related fresh-vegetable servings among pork outlets in Kampala, Uganda

“…Multidrug resistance was found in 98% of our isolates; this was much higher than those of 57% and 54% reported by Ikwap et al (2014), and Kalule et al (2012), respectively. However, these differences may be due to the different methodologies used.…”

“…have been reported in a number of countries in East Africa (Kariuki et al, 2006;Kikuvi et al, 2010;Omulo et al, 2015) and are likely to increase (Byarugaba, 2004;Sirinavin et al, 2004). Previous studies in Uganda show a high prevalence of multiresistant strains, evidence of cross-species transmission of plasmids, and drug resistance in animals and humans (Kalule et al, 2012;Tinega et al, 2016). Typing methods such as plasmid profiling, ribotyping, and pulsed-field gel electrophoresis have been used to aid diagnosis and outbreak investigation (Lukinmaa et al, 2004).…”

“…Interestingly, drugs such as ceftazidime, cefuroxime, cefotaxime, meropenem, and amikacin, which are not licensed for veterinary use in Uganda, expressed even This is the first study to use replicon typing in analyzing for presence of replicon groups in Salmonella isolates in Uganda. The study by Kalule et al (2012) used plasmid extraction to characterize plasmids from Salmonella isolates and reported the presence of five plasmids and several strains harboring more than one plasmid. The present study showed similar trends because of the detection of multiple replicon groups.…”

Antibiotic Use in Agriculture and Its Consequential Resistance in Environmental Sources: Potential Public Health Implications

“…Therefore, food or animal-derived products, including meat, milk, and eggs, may represent an active and key medium through which antibiotic resistance determinants are continually being transferred between bacteria, and from animals to humans [ 123 ]. Bosco et al [ 211 ] clearly documented the multidrug resistance of Salmonella isolates recovered from cattle, pigs, chickens, eggs, and animal-derived products, as well as cross-species transmission of plasmids between animal and humans in Uganda.…”

Prevalence and characterization of Salmonella among humans in Ghana

“…In recent years, strains of Salmonella resistant to antimicrobial drugs have spread worldwide with isolates resistant to quinolones being reported with increasing frequency in several African countries [ 26 – 28 ]. In Ghana, earlier reports have indicated the presence of Salmonella strains showing multi-resistance to antimicrobials routinely used as therapeutic agents [ 24 ].…”