Ready-to-eat vegetable salads served in Nigerian restaurants: a potential source of multidrug-resistant bacteria

A scoping review of the prevalence of antimicrobial-resistant pathogens and signatures in ready-to-eat street foods in Africa: implications for public health

Background and objective

Despite its critical role in individual and societal health, food hygiene remains underexplored. Antibiotic-resistant pathogenic bacteria in ready-to-eat (RTE) food threaten public health. This scoping review collected data on the epidemiological prevalence of RTE food-contaminated pathogens resistant to antimicrobial drugs and resistance genes in Africa.

Method

Using electronic databases, such as PubMed, Scopus, and Web of Science (WoS), handpicked from references, pre-reviewed published articles were retrieved and analyzed according to the PRISMA-ScR guidelines.

Results

The findings indicate 40 previewed published articles qualified for meta-synthesis in the scoping review with a population/case ratio of 11,653/5,338 (45.80%). The most frequently reported RTE foods were meat or beef/beef-soup, chicken or poultry products, salads, vegetable salads, and sandwiches, which harboured pathogens such as E. coli, Salmonella, and Staphylococcus. Antibiotic susceptibility tests revealed the use of 48 antibiotics to manage infections, following CLSI (Clinical and Laboratory Standards Institute) protocols. Moreover, 10 authors reported 54 resistance genes associated with pathogenic resistant bacteria. In addition, only 15 studies received funding or financial support.

Conclusion

These findings from several researchers indicate that RTE street foods in African and resource-limited nations harbour enteric pathogens and are a significant concern to the public health system and reservoir of the spread of antibiotic resistance. This underscores the necessity of implementing effective control strategies to address challenges and limit the spread of resistant bacteria in RTE foods. The antimicrobial resistance surveillance system in the region is a significant concern. Notably, Africa needs to strengthen the national and international regulatory bodies and a health surveillance system on antimicrobial resistance, particularly among developing nations.

Microbial and Parasitic Contamination of Vegetables in Developing Countries and Their Food Safety Guidelines

The safety of humans is of paramount importance in the vegetable production chain. Evidence of microbial and parasitic contamination of these products poses a great threat to consumers. This is an emerging issue the world is battling, and it is still in the process of unravelling. However, one of the contributing factors responsible for the rapid spread of these pathogens to millions of people among other factors is the distribution of food in our food systems. The purpose of this study was to draw the attention of producers, retailers, consumers, and various stakeholders to the occurrence and potential hazard of these organisms, their contamination origin, and food safety protocols. Among the food system, vegetables play a major role, and their consumption has increased as they form a larger portion of daily diets. This urge for healthy diets coupled with changing dietary habits and human population explosion has therefore accelerated their production. This has resulted in parasitic and microbial contamination gaining grounds in salad vegetables, and as such, a wide range of microbes such as Escherichia coli O157: H7, Listeria monocytogenes, Salmonella spp., Shigella, and Staphylococcus, and parasites such as Giardia lamblia, Entamoeba coli, Entamoeba histolytica, Cystoisospora belli, Toxoplasma gondii, Trichuris trichiura, and Ascaris lumbricoides have been isolated from them. Therefore, major routes for salad vegetable contamination and prevention methods have been pointed out in this review article. The topic of protective countermeasures will also be covered here in this review. Notwithstanding, several control measures have been reported to be effective and efficient in removing or eliminating pathogens, including treatment of irrigation water and fertilizers, use of disinfectants like vinegar and saltwater, irradiation, ozone, and bacteriophages. Though consumption of vegetables and salads is encouraged due to their nutritional advantage, appropriate systems should be put in place to ensure their safety.

Assessment of the Microbiological Quality of Ready-to-Eat Salads-Are There Any Reasons for Concern about Public Health?

Ready-to-eat food products can be readily consumed without further preparation and are convenient for busy on-the-go consumers. The objective of the study was to assess the microbiological quality of ready-to-eat salads. Thirty RTE salads were tested for the presence of bacteria, yeasts, and molds using the TEMPO and agar plate method. The study demonstrated that most of the tested products were characterized by varying microbiological quality. The total number of mesophilic microbiotas was about 6 log CFU g^-1. The high number of microorganisms was due to yeast and molds or Enterobacteriaceae. Half of the salads were contaminated with E. coli and three salads were contaminated with S. aureus. LAB were also found, which can be explained mainly by a dairy ingredient. In some salads, Salmonella spp. and L. monocytogenes were detected (26.7% and 33.3% of the samples, respectively). Based on the conducted tests, it was found that the microbiological quality was not satisfactory. The results presented in this study indicate that there is a significant problem of the presence of pathogens. Manufacturers should strive to reduce the possibility of microbial contamination through the use of widely understood hygiene of the production process, using hurdle technology, including the modified atmosphere and refrigerated storage.