Invasive candidiasis (IC)

What is Invasive candidiasis (IC)?

IC refers to bloodstream or deep-seated infections caused by Candida spp.¹ Candidemia specifically refers to bloodstream infections.^1,2

Disease manifestation can vary depending on the species, due to different virulence factors, invasive potential and susceptibility to antifungal medication.¹ In a hospital setting, Candida spp. colonisation has been observed on surfaces and medical devices.³ Nosocomial infections are an increasingly common route of infection and a concern for patients in high-risk groups.⁴

Pathogenesis

Pathogenesis occurs through colonisation of mucosal surfaces in the body, such as the intestines, or through the formation of biofilms on medical devices, such as catheters.¹ Deficiencies in the host immune system can allow Candida spp. to breach the intestinal barrier through hyphal penetration and dissemination into the bloodstream.¹ From here, the pathogen can move to different internal organs and establish disseminated infection, or can be localised to the bloodstream (candidemia).¹

Epidemiology

The global incidence of IC is estimated at ~750,000 cases per year.⁴ In the USA, approximately 55% of all IFDs are caused by Candida spp.⁵

It is estimated that half of all candidemia infections occur in the intensive care unit (ICU), largely because patients in the ICU have one or several risk factors for disease.¹ The cumulative incidence of IC in European ICUs is estimated to be 7.07 episodes per 1000 ICU admissions.⁶

The mortality rate for candidemia is estimated to be over 40%.⁴

Risk factors

Patients who are critically ill and immunocompromised, such as those with cancer or those undergoing bone marrow or solid organ transplant, are at increased risk of IC.⁷

Other factors associated with IC include:^2,7,8

• Renal impairment
• Use of mechanical ventilation
• Hospital stays longer than 10–15 days
• Central venous catheterisation
• Sepsis
• Total parenteral nutrition
• Use of broad-spectrum antibiotics
• Increased age
• Rare Candida spp. as causative pathogens
• Abdominal surgery

Pathogenic species

• C. albicans is the most common species that causes IC, accounting for nearly half of all Candida infections^4,9
• C. albicans, C. glabrata, C. tropicalis, C. parapsilosis and C. krusei together represent over 90% of all IC cases¹⁰
• C. auris is an emerging pathogen that has been associated with outbreaks of IC in several countries, including Japan, India, the UK, Spain, the USA, Colombia and South Africa^1,11 
• This species is of particular concern as multi-drug resistance has been observed, alongside its ability to spread between individuals and rapidly colonise the skin¹²