Succession and proliferation of opportunistic pathogens on leafy greens at retail markets.

Leafy greens consumed raw are consider potential reservoirs for opportunistic pathogens and are able to cross geographical barriers by attaching to natural apertures and thrive in new niche. This study aimed to enumerate microbiota and identify microbial species isolated from spinach (Spinacia oleracea L.) and cabbage (Brassica oleracea var. capitata L.) at markets that are mainly supplied by small-scale farms in the Free State, South Africa. Small-scale farm pre-harvest and post-harvest practises contribute to succession and proliferation of pathogens at markets. Analytical profile index (API) tests were conducted for final confirmation and identification to a specie level. Among leafy green samples enumerated, 17.4% and 13.9% were contaminated by E. coli which is highly prevalent in cabbage and spinach followed 13.1% and 13% P. mirabilis and 12.65 and 9.6% C. cloacae including 4.4% of L. monocytogenes and 4.9% L. ivanovii in spinach. Listeria species was not detected in any cabbage samples. The highest count of Enterobacteriaceae ranged from 1–4.9 log CFU/g, aerobic mesophilic bacteria ranged from 2–4.9 log CFU/g in spinach followed by aerobic mesophilic with 2–3.9 log CFU/g and Enterobacteriaceae range from 2–4.9 log CFU/g and aerobic mesophilic while the minimum was in spinach samples 1–2.9 log CFU/g for Listeria species. Agronomic parameters in small-scale farms, including the cold chain abruption, contribute to the succession of opportunistic microorganisms as they are not subjected to any lethal process employed to effectively kill pathogenic organisms. The data is crucial for evaluating the pathogenic potential trend and its aetiology regarding cold chain abruption cross-contamination, and proliferation due to opportunistic pathogenic microorganisms at markets.