Are you ready to be spooked by ghastly ghouls and grotesque monsters this Halloween? Whilst everyone has fun acting crazy in their costumes and freaking out at films, we thought we would share some real-life horror stories with you. We have compared some classic Halloween monsters and myths with some frighteningly uncanny bacteria. If you are stuck for a costume this year, you may find some ideas below!

Trick or treat

Just like trick or treating, E. coli has both a good and bad side.

When on its best behaviour, E. coli helps our bodies by colonising in our large intestine as gut flora. This helps metabolise the oxygen in the gut to produce anaerobic conditions, where aerobic bacteria find it hard to grow. In addition, the gut flora also competes with pathogens for nutrients. E. coli therefore helps our bodies prevent potential illnesses.

But when it’s bad, E. coli can be very bad. Some strains of E. coli, such as E. coli O145 and E. coli O121:H19, are known as a common source for food poisoning, causing diarrhoea, stomach cramps and vomiting. Lots of food items in your kitchen could be contaminated with E. coli. Reduce your chances of this monster getting the better of you, and make sure you wash items such as spinach and lettuce properly.

Vampires – a lust for blood

If you leave your Halloween costume until the last minute, you may be reaching for the long black cape and fake teeth to create a blood sucking vampire – again! And just like our vampire friends, Streptococcus pyogenes (S. pyogenes) also has a lust for our bodies’ favourite fluid. S. pyogenes is an example of a bacterium that attacks red blood cells and causes disturbing infections such as scarlet fever, cellulitis, and impetigo. S. pyogenes is commonly found in the throat or on skin and can be easily spread through air borne droplets. The infections brought about by it can be prevented by washing hands with disinfectants, covering mouth when coughing or sneezing and, of course, avoiding skin contact with contaminated lesions.

Mummies – lying dormant, ready to strike

No Halloween is complete without a story about a dormant mummy lying in a catatonic state and waiting to strike on its prey. Enter Bacillus and Clostridium – Gram positive anaerobic bacteria that produce endospores. Endospores are a coping mechanism that these bacteria make to be highly resistant against ecological degrading agents, so they can lie dormant and reactivate themselves to a vegetative state – ready to infect. Endospores are indeed a true nightmare to eliminate as they are resistant to heat, disinfectants, radiation, and desiccation. Since Bacillus and Clostridium can be transmitted through ingestion of contaminated food, adequate cooking and proper storage of food, as well as avoidance of contaminated food are all correct ways of prevention.

Zombies – rotting flesh

It is not only zombies that eat flesh! Some bacteria, such as Clostridium, E. coli and Klebsiella cause necrotizing fasciitis, an infection that destroys the tissues in skin and muscle. Whilst the bacteria don’t physically eat flesh, they do damage the tissue by releasing harmful toxins. Klebsiella also spreads through person-to-person contact and can be found in human intestines where it doesn’t cause diseases (like E. coli). Keep up with good hygiene routines and you should be able to steer clear from infections.

Loch Ness Monster

Just like the Loch Ness Monster, V. cholerae hides in water too. This is a bacteria which can cause an infectious disease cholera that causes severe watery diarrhoea. Cholera is caused by consuming food or water that has been contaminated with V. cholerae bacteria – green like the Scottish mythical creature and green just like the colour of the agar that cholera grows on. Stay away from good ol’ Nessie and cholera by keeping out of dirty water.

Unleash the Kraken

The Kraken is a mighty fearsome creature said to be found in the oceans of Greenland and Norway. The many tentacles of this giant octopus are similar to flagella found in some bacteria, such as Salmonella typhi. Flagella are an important feature, as they allow the bacteria to move to areas of higher nutrients or away from toxic substances.


We have all seen the films, where monsters produce a slimy ectoplasm to engulf their prey. Similarly, some bacteria form biofilms, a layer outside the cells of their bodies, allowing them to stick together and stick to inert or living surfaces. For example, bacterial biofilm can form on our teeth as plaque. Bacterial biofilm can also lead to hospital-acquired infections (HAIs), such as Clostridium difficile infection.

With so many ideas for gruesome fancy dress options, the team here at BioLabTests wishes everyone a happy Halloween!!

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