Infectious Disease

Candidiasis

Candidiasis is infection by Candida yeasts, usually a superficial mucocutaneous infection but occasionally invasive candidaemia; the key clinical task is to distinguish symptomatic disease from colonisation and match treatment to site, host, species, susceptibility and pregnancy status.

In a nutshell

Candida is normally a commensal. Diagnose symptomatic site-specific disease, distinguish colonisation from invasive infection, and match treatment to severity, host, species, pregnancy and interactions. Mild oral or vaginal disease is usually treated locally or with a suitable short course; oesophageal disease needs systemic therapy; candidaemia needs urgent specialist antifungal treatment, cultures, susceptibility testing and source control.

Classic presentation

A patient after antibiotics has sore white oral patches or vulval itch with a thick non-offensive discharge. Invasive disease is persistent sepsis or fever in a critically ill or immunocompromised patient, especially with a central venous catheter or recent abdominal surgery.

Key points

Candida from a non-sterile site may be colonisation; interpret it with symptoms, examination and host risk.
Vulvovaginal candidiasis usually has vaginal pH below 4.5; recurrent or treatment-resistant disease needs sampling and review for diabetes or immunodeficiency.
Avoid oral anti-thrush tablets in pregnancy without clinician advice; use an appropriate topical vaginal antifungal.
Miconazole oral gel can markedly increase warfarin anticoagulation and is contraindicated with warfarin.
Oesophageal candidiasis requires systemic treatment; candidaemia requires urgent specialist therapy, susceptibility testing, repeat cultures and source control.
A Candidozyma auris isolate follows the UKHSA healthcare pathway because resistance and transmission risks differ from routine thrush.

First-line investigation

Clinical examination for typical superficial disease; sample recurrent, severe, uncertain or treatment-resistant mucocutaneous disease; obtain blood cultures and urgent microbiology input for suspected invasive candidiasis.

Management

Recognise emergencies and red flags

Escalate shock, organ dysfunction, neutropenia, severe immunosuppression, painful swallowing with dehydration, or Candida from blood or another normally sterile site.^9,4,3
In suspected invasive candidiasis, obtain cultures promptly, start sepsis care and contact microbiology or infectious diseases without delaying urgent treatment.^9,4

Confirm the syndrome and risk

Typical oral, vulvovaginal or flexural disease is usually clinical; sample disease that is severe, recurrent, atypical, persistent or treatment-resistant.^2,7,10,3
Review antibiotics, diabetes, HIV risk, immunosuppression, neutropenia, central lines, abdominal surgery, parenteral nutrition and other barrier breaches.^1,2,4

Treat superficial disease safely

Use a topical oral antifungal for localised oral thrush, check the miconazole-warfarin interaction, and clean dentures or rinse after inhaled corticosteroids.^2,11,8
Use an intravaginal azole or suitable oral fluconazole for uncomplicated vulvovaginal disease only when appropriate; use topical treatment with clinician advice in pregnancy and do not routinely treat asymptomatic partners.^1,6,7,10,8

Manage systemic and recurrent disease

Treat oesophageal candidiasis systemically and involve specialists for inability to take oral treatment, recurrence, resistance or significant immunosuppression.^4,8,2
For candidaemia, use an echinocandin as the usual initial specialist-directed option, obtain species and susceptibility results, and remove or replace an infected central line when safe and appropriate.^4,3,8

Document clearance and prevent recurrence

Repeat blood cultures until clearance, assess for deep or metastatic infection when indicated, and continue specialist-directed treatment for the required duration after clearance and symptom resolution.^4,3
Reassess recurrent or treatment-resistant disease rather than repeating empiric treatment; address diabetes, unnecessary antibiotics, inhaler or denture factors and immune dysfunction.^1,2,7,10

Exam traps

A positive vaginal or other non-sterile-site Candida result without symptoms does not automatically mean treatment is needed.
Normal vaginal pH supports candidiasis; a raised pH should prompt consideration of bacterial vaginosis or trichomoniasis.
Do not use oral anti-thrush tablets in pregnancy without clinician advice.
Miconazole oral gel is not a harmless topical preparation: it is systemically absorbed and interacts dangerously with warfarin.
Candida in sputum or urine may be colonisation; invasive disease needs clinical correlation and specialist assessment.
Candidaemia is not managed like uncomplicated thrush: obtain cultures, start appropriate systemic therapy, investigate the source and document clearance.

Illustrations

Oral candidiasis (thrush)A clinical photograph of the tongue and buccal mucosa showing white pseudomembranous plaques that can be wiped away to reveal an erythematous base.Photo Credit: Content Providers(s): CDC, Wikimedia Commons · Public domain

Candida pseudohyphae on wet-mount microscopyVaginal wet mount showing branching Candida pseudohyphae and yeast forms, with arrows marking representative filaments.Mikael Häggström, Wikimedia Commons · CC0

Key sources

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.