Analysis Guide

Every analysis answers one question: what happens if this parameter goes unnoticed? We explain why the parameters in our catalogue are tested, which illness they cause and what the regulations require — with the sources cited.

Sample type

Food

Why is Salmonella tested for? A risk you cannot see, starting within 6 hours

Because contaminated food cannot be told apart by taste or smell, and by the time symptoms appear the chance to sample has passed.

Food contaminated with Salmonella looks, smells and tastes normal. The illness shows its first symptom 6–72 hours later — by which time everyone who ate from the same batch is already affected. The analysis exists to close that gap.

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Food

Listeria monocytogenes: refrigeration does not stop it, and 20–30% of invasive cases are fatal

Because it is the one major food pathogen that multiplies in the cold: its numbers can rise in a product assumed safe for its whole shelf life.

In food safety the cold chain is a line of defence. Listeria monocytogenes crosses it: it survives and multiplies at refrigerator temperatures. Invasive listeriosis has a 20–30% fatality rate, and incubation can extend to 90 days.

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Food

E. coli O157: the 10% path from bloody diarrhoea to kidney failure

Because even a very small dose can cause severe kidney damage, and any part of the food that stays below 70 °C leaves the bacterium alive.

Shiga toxin-producing E. coli leads somewhere most food pathogens do not: up to 10% of patients develop haemolytic uraemic syndrome, which is fatal in 3–5% of cases and mainly affects children.

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Water

Legionella: an illness you catch by breathing in the shower, not by drinking

Because a facility’s water can be clear and chlorinated while the bacterium grows in a low-flow branch; the risk only becomes visible by sampling that point.

Legionella is not caught by drinking water; it is caught by inhaling water droplets. The bacterium lives in water systems and grows between 20 and 50 °C — exactly the range of a little-used hotel room shower, a cooling tower or a spa.

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Food

Staphylococcal enterotoxin: you killed the bacterium, the poison stayed

Because once the toxin has formed, cooking does not solve the problem; the only way is to prevent it forming — and to measure whether it did.

One of the most counter-intuitive facts in food safety: Staphylococcus aureus is killed by heat, the enterotoxin it produced is not. Symptoms start within 1–7 hours, and less than 1 microgram of toxin is enough.

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Food

Bacillus cereus: a toxin that survives 121 °C for 30 minutes — and the hot-holding mistake

Because its spores survive cooking; the longer a product stands warm the more it multiplies, and the toxin formed cannot be destroyed by reheating.

Cereulide, the emetic toxin of Bacillus cereus, is stable after heating at 121 °C for 30 minutes, after 60 days at 4 °C, and across pH 2 to 11. The problem is not the cooking, it is the holding temperature afterwards.

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$Close-up of light refracting on a pool water surface$ Pool water

Zero tolerance in pool water: the limit for Pseudomonas, E. coli and coliforms is 0/100 ml

Because a pool that looks clear and chlorinated may still fail the regulation’s zero tolerance — and the result has to be displayed publicly.

Turkish swimming pool regulation defines no tolerance for three organisms in pool water: the limit for total coliforms, E. coli and Pseudomonas aeruginosa is 0/100 ml. If non-conformity persists, the regulation provides for the pool to be shut down.

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Water

Coliforms and E. coli in water: clarity is not evidence

Because these bacteria are the only practical indicator of faecal contamination: if they are present, the water path has been breached somewhere.

Microbiologically contaminated water is estimated to cause approximately 505,000 diarrhoeal deaths each year. Water being clear, odourless and tasteless does not measure that risk; measuring it is exactly what coliform and E. coli testing is for.

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Surface / Environmental

The counter that looks clean: what do swabs and contact plates measure?

Because bacteria left on a surface pass to every new batch: assurance comes from the procedure being measured, not from it being written down.

Surface cleanliness cannot be verified by eye. Swabs and contact plates are the only objective evidence that a cleaning and disinfection procedure actually works — and for some pathogens they sit alongside product testing, not instead of it.

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Food

Moulds and yeasts: counted before visible spoilage, because after the mycotoxin it is too late

Because a mould count warns that drying and storage conditions have slipped, before the product visibly spoils.

By the time mould is visible, the damage is done. And the mould is not the real issue: most of the mycotoxins it produces are chemically stable and survive food processing. Cutting the mould off does not remove the toxin.

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Food

Vibrio: two separate risks in raw seafood, one of which can kill within hours

Because these bacteria are natural inhabitants of seawater; they can be present without the product being spoiled, and chilling does not reliably remove them.

Vibrio cholerae causes watery diarrhoea that can be fatal within hours if untreated. Vibrio parahaemolyticus is usually milder — but when it turns into septicaemia, 20–30% of cases are fatal. Both live in the marine environment.

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Food

Aerobic colony count: it causes no illness, but it is the first to tell you the process has slipped

Because it is the one routine parameter that shows numerically that process hygiene has slipped, before a pathogen shows up.

This count does not look for a pathogen and never says on its own that a food will make someone ill. What it does is more useful: when cleaning, chilling or raw material quality slips, the number rises before any pathogen appears.

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Food

Rope spores: the spore that survives inside the loaf that came out of the oven

Because the spores arrive naturally with the flour and baking does not destroy them; the risk has to be measured at the flour stage.

As bread bakes, the core temperature stabilises slightly below 100 °C — enough to kill vegetative cells, not enough to kill spores. Under the right conditions the surviving Bacillus spores turn the crumb into a sticky, stringy mass.

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Pool water

Adding chlorine is not enough: if the pH is wrong, the disinfectant is not working

Because without measuring pH, alkalinity and temperature you cannot know what a free chlorine reading actually means.

Chlorine added to water splits between hypochlorous acid and hypochlorite ion according to pH. Hypochlorous acid is a far stronger disinfectant. The same free chlorine reading therefore means different killing power at different pH.

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Pool water

Cyanuric acid: it shields chlorine from the sun, then builds up and gets in its way

Because the stabiliser accumulates in the water, does not decline on its own, and can only be seen by measuring it.

In outdoor pools, chlorinated isocyanurates slow the sun from destroying chlorine. But the cyanuric acid left in the water accumulates; WHO recommends it should not exceed 100 mg/l in pool water. It is a helper that has to be measured.

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Water

Nitrate, nitrite and ammonium: why the water for a bottle-fed infant is a separate question

Because these three compounds are the first chemical signs that agricultural fertiliser or wastewater has entered the water source.

WHO’s guideline values for nitrate and nitrite are set not for adults but for bottle-fed infants. The reason is that the enzyme protecting against methaemoglobinaemia is deficient in infants until about six months of age.

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Water

Aluminium, copper and iron: all three usually come from the pipe, not the source

Because when a result rises the problem is usually not in the source but in the treatment or in the building’s own plumbing.

These three metals look like one group, but each answers a different question: one comes from the treatment itself, one from corrosion of the plumbing, one concerns the acceptability of the water. WHO treats all three differently.

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Water

Colour and conductivity: no health limit, yet the first warning comes from them

Because both are cheap and fast; when they change they are the first to reveal a problem that has not yet been named.

WHO proposes no health-based guideline value for colour. It nevertheless asks that a substantial change in colour be investigated — because colour may be the first indication of a hazardous situation.

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