Introduction

Male yeast infections, medically known as candidiasis or thrush, are a fungal infection. This infection is caused by certain species of the fungus called Candida. The fungus occurs naturally in warm, moist parts of the human body, such as the mouth and genitals. However, under certain conditions where the fungus becomes overgrown, it can elicit pathogenic effects on its host.¹

Certain tests are carried out on male patients who present with symptoms of yeast infections. These tests usually include: swabs, microscopy, and sample cultures. These tests help the doctor to accurately diagnose these male patients and prevent mismanagement of patients' health.

In this article, we will compare the diagnostic accuracy of the various tests (swabs, culture, and microscopy) for yeast infections in males. This is important as it would enlighten the public on which test is most reliable in diagnosing male yeast infections.

Aetiology and pathophysiology

Most male yeast infections are predominantly caused by the fungus Candida albicans. Candida albicans causes candidiasis and candidal balanitis (inflammation of the tip of the penis).² Studies show that other species of Candida (non-albicans Candida) such as Candida tropicalis and Candida parapsilosis can also be infectious.³

The presence of Candida in one's body isn't a sign of infection. This is because Candida is an opportunistic infection. This simply means that Candida occurs naturally with the body's normal flora (bacteria). However, Candida may become pathogenic to its host when the host becomes immunocompromised due to certain increased risk factors that develop into ailments.¹

For most men, the most common risk factors for yeast infections are tuberculosis, smoking, intravenous (IV) tubes, antibiotic abuse, poor hygiene, unprotected sexual intercourse, catheterisation, and nutritional deficiencies.¹

Clinical presentation

Male patients with a yeast infection typically present with certain symptoms like:^4,5

• Itching red rashes on the genitals
• Burning sensations on the penis tip
• Foreskin inflammation occurs during severe cases
• Painful urination and ejaculation
• Tiny cracks and cuts on the foreskin

Although these symptoms are usually present in most male patients with yeast infections, in certain cases, some patients with yeast infections can be asymptomatic.

It is therefore important that proper diagnoses of yeast infection in male patients should be looked into, as some of the listed symptoms also overlap with those of certain bacterial sexually transmitted infections (STIs).

Diagnostic methods overview

After carefully taking your patient history and examining the affected area, usually the genitals, the doctor may likely recommend three main laboratory diagnostic methods of detecting and identifying a yeast infection in male patients. Here's an overview of these diagnostic tests and the role they play in proper patient diagnosis.

Swab sampling

Technique: penile swabs from glans/prepuce

This test technique simply involves using a sterile swab stick, labelled with the patient's name and other available patient information, to properly collect specimen samples from the affected area. The swab stick is rubbed gently on the glans penis and other parts of the genital that discharge pus. In some cases, urethral swab samples might be taken.²

Advantages

• Swab samples are usually non-invasive and, as such, may cause very little pain, if any
• Swab sample collection is usually quick and requires no special apparatus

Limitations

• It must be collected by a trained medical professional, such as a doctor or laboratory scientist
• There is also a risk of contamination during the sample collection process

Microscopy (KOH wet mount / gram stain)

Principle: The main purpose of microscopy is to identify the microscopic features of the yeast cells, which are their budding forms and pseudohyphae. The sample collected will either undergo a staining process called Gram staining or potassium hydroxide (KOH) mounting. Gram staining helps identify yeast cells as they take up the colour of the primary stain (crystal violet) and appear purple, while the KOH mounting will dissolve the various human surroundings, exposing the yeast cells and their shape, making it easier to spot them.⁶

Advantages

• A major advantage of this method is that it is quick to carry out and reliable in identifying yeast infections
• It is also cost-effective, as it makes use of readily available lab equivalents

Limitations

• Its main limitation is its low sensitivity during mild or early infections, which could result in false-negative test reports

Culture

Principle: Cultures are a very good test standard for diagnosing yeast infections. With fungal cultures, after the sample is taken from the male patient's genital region, it is then inoculated onto Sabouraud agar or chromogenic media. The fungus is then incubated at a specific temperature for a period of time, after which the yeast fungi are identified based on their morphological and biochemical features.

Advantages

• Culturing is widely considered the gold standard of fungi and bacteria identification globally
• It provides easy identification of various species of yeast cells
• Most importantly, the use of culture media helps in antifungal susceptibility testing for the yeast infection, which helps the doctor identify which antibiotics to prescribe to eradicate the infection

Limitations

• A major limitation of culturing is that it is time-consuming, with results taking 48 to 72 hours
• Cultures can also detect colonisation rather than infection. Simply put, they could yield positive results similar to those seen in asymptomatic males

Comparative diagnostic accuracy

Over time, certain studies suggest that culture is the gold standard in testing for various fungal infections, including yeast infections. Culture is considered to have a higher sensitivity and specificity for yeast infections and also provides treatment options with antifungal susceptibility testing, where the fungi are exposed to various antibiotics at certain doses to find the antibiotics that best eradicate it.

Microscopy is a fast approach to testing for yeast infections; it has a lower sensitivity than that of cultures. Recent studies suggest that microscopy using KOH mount can have a sensitivity for Candida species as low as 29%.⁶

With swabs, they are simply a method of sample collection. As such, they provide little to no help in diagnosing yeast infections on their own. Hence, a more effective approach to achieving optimum results in diagnosing yeast infections in male patients would be to pair all three tests together. This would help mitigate each test's limitations while leveraging their strengths to achieve an accurate patient diagnosis.

Challenges and limitations

A major challenge posed by all three test methods mentioned in this article is differentiating pathogenic yeast infections from normal colonisation. As stated earlier, Candida is considered part of the normal flora and, as such, is found in healthy asymptomatic males.

Other factors, such as poor or inadequate sample collection, early infections, and abuse of antifungal medication, further increase the chance of false-negative reports.⁷

So far, there are no joint, universally accepted diagnostic criteria for diagnosing male yeast infections, unlike for women with vulvovaginal candidiasis. This causes slight variability in clinical diagnosis and practice.

Recommendations for clinical practice

A suggested diagnostic strategy for clinical practice in diagnosing yeast infections in male patients is as follows:

First consultation

It is important to discuss the symptoms you may be experiencing with your doctor. Do not hold anything back. If the symptoms are suggestive of a yeast infection, a penile swab will be collected.

Investigation

This phase will involve a microscopy test using a KOH mount or Gram staining to help identify whether any yeast cells are present.

Confirmatory/follow-up tests

If false-negative results are suspected, due to recurring symptoms or clinical suspicion, a culture will be carried out to confirm the presence and extent of the fungal infection.

Direct culture

This approach mostly applies to immunocompromised patients, as they are most likely to be at risk of these infections.

This strategy covers all the key aspects of detecting yeast infections in male patients and could help reduce the risk of false-negative reports.

Summary

No diagnostic test for male yeast infections is foolproof. Culture is considered the gold standard in some studies, as it is sensitive, reliable, and helps in identifying Candida and other species. However, its long duration can pose an issue, especially for patients who require immediate treatment. Microscopy, being the second alternative, is both cost-effective and fast, but its low sensitivity poses a significant challenge for diagnosis.

Hence, a combined reliance on both tests should be opted for. This will help ensure proper diagnosis and better treatment outcomes.