Enumeration of phyllo-epiphytic and endophytic pathogens on leafy greens from farms and retails as affected by production parameters in the Free State, South Africa.

Abstract

Leafy vegetables are a highly variable group of perishable foods that broadly can be defined as vegetables grown for their edible leaves. This study was conducted to investigate the production parameters at the farms and how they influences the end product. The study characterises opportunistic pathogens from various farms and retails and identify the aetiology and how these organisms affect human health and also emphasise the significance of sources that are regarded as microbial hazards or act as resevoirs for pathogenic organisms. Considering one health perspective it is also imperative to pay more attention to the presence of zoonotic pathogens that are resistance to certain antbiotics as it is a public health threat and a challenge that need to be highlighted due to high level of infectious illness caused by zoonotic and opportunistic pathogens. Since various agronomic activities leads to contamination of leafy greens in various stages of minimal processing including distribution, it is thus crucial to address such concerns at small-scale farms to mitigate cross-contaminate to the retails and provide an insight on hygiene and sanitation in both spheres. Minimal process includes many stages which introduces the disruption of tissue including cell integrity resulting in product harbouring of opportunistic pathogens. Spinach (Spinacia oleracea L.) and cabbage (Brassica oleracea var. capitata L.) are considered staple food in South Africa and are consumed daily, they were chosen due to their minimal processing in production, demand, purchase and their difference compared to intact vegetables regarding their physiology, processing, handling including storage. The study profiles and characterise opportunistic and zoonotic pathogens from both regimens due to processing parameters, hygiene practises and possible succession of pathogens form one niche to the other. The first survey was on the enumeration of microbiota on spinach and cabbage isolates from various farms including their storage crates. Secondly, the objective was to enumerate microbiota from spinach and cabbage from retails and further investigate the extent of these pathogens, the succession at the retail level, observe the proliferation of pathogens introduced along the way due to amplification. Fresh leafy spinach, crates and cabbage samples were analysed for each of the following microorganisms: total aerobic mesophilic bacteria, total coliforms, coagulase-positive Staphylococci, Listeria and Bacillus and further identification of isolates was done by utilisng Analytic Profile Index. Lastly, conduct antimicrobial susceptibility profile of identified opportunistics bacteria from farms and retails, the isolates were evaluated utilising Kirby-Bauer disk diffusion method against nine antibiotics from nine categories: penicillin (P; 10_μg), ampicillin (AMP; 10_μg), gentamicin (CN; 10_μg), ceftazidime (CAZ; 30_μg), chloramphenicol (C; 30_ μg), tetracycline (TE; 30_μg), vancomycin (VA; 30_μg), erythromycin (E; 15_ μg) and ciprofloxacin (CIP; 5_ μg). In this study, three farms had the highest number of opportunistic pathogens identified for cabbage with the least number of pathogens observed in the other two farms. With regards to spinach, two farms had the highest number of identified pathogens including Proteus mirabilis, Escherichia coli, Staphylococcus aureus, Serratia species and Listeria species and the lowest number was observed in the other two farms. Concerning spinach crates, two farms had the highest number of pathogens identified and the least numbers were observed in the other two farms. This indicate contamination mostly from livestock manure utilised on the crops including insufficient hygiene from workplace. Secondly, three retails had the highest number of pathogens identified for cabbage compared to the other two retails. With regard to spinach, three retails had the highest number of identified pathogens including Bacillus spp., Enterobacter cloacae, Listeria ivanovii and Listeria monocytogenes species compared to the other two retails. The study also highlights additional bacterial species enumerated from both commodities in two different environments. The additional species characterized are a result of proliferation introduced due to agronomic parameters, cold chain supply, and retail activities. The combined result of total coliforms and opportunistic pathogens found on the end-products indicates poor minimal processing, poor hygiene and sanitation standards. Lastly, Enterobacter cloacae, Staphylococcus aureus, Micrococcus luteus, Staphylococcus sciuri, Acinetobacter haemolyticus, Burkholderia cepacia, Psuedomona luteola, Escherichia coli, Citrobacter freundii and Serratia marcescens were tested again nine antibiotics. Multidrug resistance was observed with 79% resistance, this is a public health threat that points out challenegs regarding treatment of infections caused by these opportunistic and zoonotic pathogens. Rapid identification of antibiotics is essential and crucial for the development of effective antimicrobial compounds as well as prevention of antibiotic resistance. Necessary measures should be taken to reduce the level of contamination from small-scale farms to reduce antibiotic consumption in humans.