You may not have been aware but last year a BBC Watchdog investigation revealed that ice used in coffees served up in major high street coffee chains was found to contain traces of faecal coliform bacteria; with the likes of Costa, Starbucks and Caffe Nero being the main culprits. Experts – including a leading researcher employed in the field of food-borne pathogens – expressed concern over the 2017 discovery, and concluded that the most likely cause of contamination was unclean hands coming into direct contact with the iced water in typical café scenarios. Having said that, they also added that ice machines (and buckets) might have compounded the issue, should they not have been subjected to rigorous and habitual cleaning prior to use. 

So just what are coliform bacteria and what does their presence indicate?

Well, staying with this particular example, it’s generally understood that coliforms are an indicator of faecal contamination; which essentially means that pretty much anything which is in faeces could make its way into iced water if we’re not careful. Let us explain further. Akin to the air that we all breathe and the food we consume, drinking water is not sterile. But rest assured, it doesn’t necessarily need to be. What water should be free from however, is pathogens; which are of course micro-organisms with the potential to spread disease. Now, total coliforms belong to a group of bacteria commonly found in our natural environment, with soil and vegetation chief amongst hosts, if you like. Elsewhere total coliforms can be present in the intestines of mammals, including us humans. E.coli (or to afford it its proper name, Escherichia coli) has been identified as the only member of the total coliform bacterial group to be found in the intestines of mammals (including humans), and when E.coli does manifest in water this tends to be as a direct result of recent faecal compromising a water source. What’s more, it may suggest the possible presence of disease-causing pathogens, such as bacteria, viruses, and parasites. But that’s not to say that all E.coli bacteria poses a health risk, as most remain relatively harmless to humans, with the noted exceptions of strains such as E.coli 0157:H7; which can lead to illness. So, whilst total coliform bacteria per se is not recognized as an illness trigger, its presence historically indicates that a water supply may therefore be more susceptible to the risk of contamination, courtesy of more harmful microorganisms, to clarify. 

Continuing on the subject of sources of pathogens discovered in drinking water, and along with the aforementioned human or animal waste, previous cases have highlighted that improperly-treated septic and sewage discharges and storm water run-off are also contributing factors which can’t be overlooked. To better illustrate this, imagine a heavy downfall of rain, and after said deluge rivers, lakes and even groundwater become vulnerable to bacteria and harmful microorganisms having washed into (and subsequently penetrated) these naturally-occurring water courses. In terms of health risks in a broader sense, it’s virtually impossible for innocent parties to determine from smell, taste or colour alone whether or not coliform bacteria has permeated into a particular water source. Ultimately, detection is only guaranteed via laboratory testing.

Health-wise, What Areas of the Body are Most at Risk from the Presence of Coliform Bacteria?

Physical effects observed and ramifications regarding an individual’s wellbeing of those who have been exposed to disease-causing bacteria, viruses or parasites more commonly associated with coliform bacteria in their drinking water, are varied. Authorities on the subject underline that symptoms most likely to present should someone be affected are nausea, vomiting and diarrhoea; and that infants, elderly people and those with compromised immune systems are more prone to suffering from the more severe symptoms. The lungs, skin, eyes, nervous system, kidneys or liver may also become infected by some pathogens in the more extreme and chronic cases. 

As we’ve already established, coliform bacteria belong to the enterobacteria family; a group of pathogens with a nasty habit of causing gastrointestinal ailments first and foremost, and which traditionally become perceptible after an individual has unwittingly ingested contaminated food or water. Examining the key bacterial threats to the human body and its in-built defences, and shigella, (which causes dysentery), certain strains of E.coli (as mentioned earlier, and which can cause urinary tract infections and diarrhoea, together with typical gastroenteritis symptoms) and salmonella (which causes diarrhoea and vomiting) are the predominant extent of health outcomes.

What Happens Next: In Terms of Microbiological Scrutiny When Coliform Bacteria Presence is Mooted?

Water sampling and industry-proven treatments are critical in instances when coliform bacteria is identified in water sources, and are frequented throughout the UK as a means of monitoring and controlling both the quality and moreover, safety of a specific area of concern. Microbiological examination of water extends to all potable waters (that which is intended for drinking or use in food preparation), treated recreational waters (swimming pools, spa pools and hydrotherapy pools), and untreated waters used for recreational purposes (such as sea, river, and lake water). Such scrutiny determines if the water is found to be safe to either drink or bathe in at a particular time and place.

Approved coliform bacteria testing methodology used can range from membrane filter and multiple tube fermentation to MPN and MMO-MUG practices. The membrane filter method uses a fine porosity filter which can retain bacteria, which is introduced to a petri (culture) dish on a pad with growth enrichment media, and is then incubated for 24 hrs at 35 degrees C.  Alternatively the MPN (most probable number) method uses a test tube full of media with a smaller inverted test tube inside which captures carbon dioxide gas released from the growth of coliform bacteria. A series of dilutions and replicates are set up, and those producing gas in 24 hrs at 35 degrees C are counted. Once this process is completed, a statistical analysis is used to work out the most probable number of bacteria cells present.

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