Microbiology: Sample, Swabs + What They Tell Us ✨

Microbiology can sound intimidating.

There are difference samples, different swabs, different organisms + different lab forms to complete. But, it can become simpler if you break it down into a few questions:

• is there an infection?
• what might be causing it?
• has the right sample been taken?
• what does that sample actually tell us?

For SVNs, understanding the basics of microbiology can make sample collection + handling feel much less overwhelming. 

✨ What is microbiology?

Microbiology is the study of microscopic organisms.

In veterinary practice, this usually includes things like:

• bacteria
• fungi 
• yeasts
• viruses
• parasites

When we talk about microbiology in practice, we are often talking about identifying organisms that may be involved in infection.

This might be from:

• a wound
• an ear
• urine
• skin
• an abscess
• a surgical site
• respiratory samples

The aim is to help the veterinary team understand what is present + whether it may be clinically significant.

✨ Why do we take microbiology samples?

Sample are usually taken when we need more information about what is going on.

For example, if a patient has:

• a wound that is not healing 
• recurrent ear infections
• a suspected urinary tract infection 
• discharge from a surgical site
• an abscess 
• skin disease that keeps coming back
• an infection that is not responding as expected

A sample can help give a clearer picture of what might be going on.

It is about finding the specific bacteria, but it is also about whether the organism fits the patients signs and/or symptoms.

✨ Colonisation vs. infection

This is important to understand - because if an organism is present, it doesn't necessarily mean it is causing disease.

Colonisation

This means microorganisms are present, but they are not necessarily doing any harm.

This can happen on the skin, in the mouth, in the ears + in other areas of the body.

Some bacteria can be part of the normal flora, depending on where it is found.

Infection

Infection means microorganisms are multiplying + causing problems.

This may lead to signs such as:

• redness
• swelling
• heat
• pain
• discharge
• odour
• fever
• delayed healing

So a microbiology result always needs to be interpreted alongside the patient - positive/negative results all depend on the clinical picture.

✨ Why sample collection matters

Microbiology results are only as useful as the sample that was collected.

If the sample is contaminated, taken from the wrong area, stored incorrectly or delayed in being sent to the lab, the result may not be very helpful.

This is why sample collection matters so much.

A good sample can support diagnosis + treatment decisions, where a poor sample can make things harder.

✨ Common microbiology sample in practice

Some common samples you may come across include:

Wound swabs:

• these may be taken from wounds with discharge, delayed healing or suspected infection.
• where possible, the area should be sampled in a way that reduces surface contamination.

Ear swabs:

• ear swabs are commonly used in patients with otitis, especially if infections are recurrent or not responding to treatment.

Urine samples:

• urine may be sent away for culture if a urinary tract infection is suspected.
• how the urine is collected can affect how reliable the result is, so the method of collection matters.

Skin samples:

• skin samples may be used in patients with recurrent skin disease, pyoderma or suspected yeast involvement.

Abscess samples:

• samples from abscesses can be useful, especially if collected from deeper material rather than surface discharge.

Surgical site samples:

• there may be taken if there is discharge, swelling, wound breakdown or concern about infection after surgery.

✨ Swabs: useful, but not perfect

Swabs are used a lot because they are quick, simple + easy to send away.

They can be useful for:

• wound discharge 
• ear infections
• superficial skin lesions
• surgical site discharge 

However, swabs can pick up surface contamination, especially if they touch surrounding skin, fur or old discharge.

This potentially means the result may show organisms that are present on the surface, rather than the ones actually causing the problem.

✨ The nurse's role

Veterinary nurses are involved in taking microbiology samples more than they realise: 

• preparing equipment 
• supporting patients + handling
• assisting with sample collection
• labelling samples correctly
• completing lab forms accurately
• storing samples appropriately
• sending samples to the lab
• following infection control precautions

A missing label, wrong sample pot, poor history or a sample that has been delayed can all affect the overall result.

✨ Common mistakes to avoid

• touching the swap on surrounding skin or fur
• mistakingly swabbing dried discharge, rather than fresh material
• using an incorrect sample container
• not labelling the sample clearly
• not adding enough detail to the clinical history
• leaving samples for too long before sending
• forgetting PPE or infection control protocols

✨ Final thoughts

• microbiology helps identify organisms that may be involved in an infection
• not every organism found is causing a disease
• samples need to be interpreted alongside the patient + their clinical history
• good sample collection makes results more useful
• swabs are helpful, but can be limited by contamination
• nurses play a key role in the handling of samples + infection control

I really hope this helps! Thank you so much for reading, Jade 🤍