Systemic candidiasis

Candida species are present as normal flora in humans. Therefore, systemic candidiasis often has an endogenous source of infection, primarily the gastrointestinal (GI) tract. Although mucocutaneous disease is common, invasive disease is not, and the primary reason is that Candida species in general are unable to traverse intact epithelium. C glabrata and C tropicalis are known to colonise the GI tract, whereas C parapsilosis tends to colonise skin and intravascular catheters. C parapsilosis can also be found on the hands of healthcare workers.

Common Candida species associated with candidaemia and systemic candidiasis include:

• C albicans

• C glabrata

• C tropicalis

• C parapsilosis

• C dubliniensis

• C krusei

• C kefyr

• C lusitaniae

• C auris.

Candida species have specific receptors that assist in binding to mucosal surfaces.[2]Pappas PG. Invasive candidiasis. Infect Dis Clin North Am. 2006 Sep;20(3):485-506. http://www.ncbi.nlm.nih.gov/pubmed/16984866?tool=bestpractice.com The primary event in the transition from superficial infection to systemic, invasive infection or colonisation is a disruption of the epithelial barrier, usually through insertion of an intravascular catheter. Other routes of infection include disruption of the gut mucosa, for instance through ulceration due to chemotherapy in patients with neutropenia, and rarely from focal infections such as pyelonephritis secondary to an ascending urinary tract infection. The alteration of normal flora by giving broad-spectrum antibiotics allows the yeast to proliferate in high numbers during invasion.