Microbiology Picture Quiz: Number 8: Answers

Have a look at the picture below and answer the questions below.



1) What type of sample is this likely to be and what is the diagnosis?

This is a “sellotape slide” demonstrating eggs of Enterobius vermicularis (pinworm/threadworm). A strip of sellotape is applied to the peri-anal area just after the patient awakes (before washing) and then applied to a microscope slide. Three slides on consecutive mornings are recommended to increase sensitivity.


 2) What are the other ways to diagnose this micro-organism? (What type of sample is not recommended?)

The eggs can also be looked for in a sample from the patient’s fingernails. (itch/pruritis is a cardinal feature of this infection….)

A stool sample is NOT recommended for laboratory diagnosis of Enterobius infections as the eggs are “diluted”, increasing the risk of false negative results.

Sometimes the diagnosis is obvious clinically and the worms can be visualised on the peri-anal skin and bedclothes/pyjamas after the patient wakes in the morning.


3) (for clinicians!) Outline treatment options for this infection?

Mebendazole, albendazole and pyrantel embonate all have activity against Enterobius infections. Usually given as a single dose then repeated after 2 or 3 weeks.

It is usually recommended that all family members are treated. Other preventative measures are listed below.

  • Daily washing of anal region.
  • Daily changing of underwear and nightwear.
  • Hot laundering of clothes.
  • Keeping fingernails short. 
  • Showering as opposed to bathing.


For your information here is the life cycle of Enterobius, and this should explain the preventative measures…





2 thoughts on “Microbiology Picture Quiz: Number 8: Answers

  1. Although rarely it is also possible to find these eggs during a routine examination in a urine sample.
    Let’s all bear in mind that automated instruments can never replace the job of an experienced “eye” with microscope.

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