As a student of microbiology, I am not oblivious to the concept that most living organisms possess normal flora. Normal flora typically describes the collection of microbes present in any given region of an organism.
These microbes are generally considered non-pathogenic and could only assume a pathogenic (opportunistic) status in an immunocompromised individual. The beneficial role of normal flora includes fighting pathogens either by competing with them for space and nutrients or by producing substances that hinder their growth.
On November 20, I was taken aback when I found that a couple of Agar plates, I had left on the lab bench had significant colonies of microbes on them. The Agar plates included PCA, DRBC, and MYP. Upon close examination, it was discovered that there was at least one dead or trapped ant on the surface of the ‘contaminated Agar plates.’ Per this, I knew the source of the contamination- ANTS!
Despite my disquiet, I was not alarmed by the growth/colonies observed on PCA. This, in part, stems from the fact that PCA is a general-purpose media and will support the growth of non-fastidious microbes. Conversely, the growth on MYP and DRBC agar plates alarmed me. Unlike PCA, MYP and DRBC are selective media for the enumeration of Bacillus cereus and yeast and mold respectively.
I quickly browsed the internet for materials to unfed my ignorance. Surprisingly, a ton of scientific research has been done on ants as vectors of pathogens. Pathogenic microorganisms that have been detected and isolated from ants include Bacillus cereus, Clostridium perfringens, Salmonella spp., Klebsiella pneumoniae, Pseudomonas spp., Escherichia coli, Micrococcus spp., etc. The risks posed by these bacteria are outside the purview of this article. Nonetheless, considering the selected theme, “Tiny Terror: Ants as Food Pathogen Transporters,” a succinct overview of a few of the above-mentioned microorganisms can be found in the glossary of this essay.
Like most scientists, I wanted to be certain of my observations, so I purposefully caught a few ants and put them in the previously described media. The observation was the same as it was before. At this point, I reflected on the various instances I have witnessed people eat ant-infested foods after the ants had been physically removed. As part of my case assessment, I uncovered that these ants originated from used agar plates that had not yet been autoclaved. This can be likened to our domestic homes, where these tiny terrors are drawn in when trash is left out for extended periods. Ants “pick up” these pathogenic microbes while they traverse rubbish areas and other unhygienic areas. So, the next time you encounter an ant on your plate, drink cup, or meal, consider them to be potential agents of FOOD POISONING!
Glossary:
• PCA denotes Plate Count Agar: used for the enumeration of mesophilic aerobic bacteria from samples including food and water.
• DRBC denotes Dichloran-Rose Bengal Chloramphenicol Agar: a selective medium for the enumeration of yeasts and molds associated with food spoilage.
• MYP denotes Mannitol Egg Yolk Polymyxin Agar: selective media for the detection of _Bacillus cereus_ in foods.
• _Bacillus cereus_ and _Clostridium perfringens_ are spore-producing bacteria that can withstand cooking temperatures. Both microbes rank among the leading causes of food poisoning in the world.
• _Salmonella_ spp. is responsible for several foodborne outbreaks and typhoid cases.
Reference:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6604928/
https://www.cdc.gov/foodsafety/diseases/clostridium-perfringens.html
Written by:
Alexandra Daplah Mwinbong (Research and Teaching Assistant, Faculty of Biosciences, UDS)
Joseph Nzeh (Member, Emerging Scholars Hub // +233246903245 // paakwesy@gmail.com )
