Disseminated Invasive Candidiasis in an Immunocompetent Host
As previously discussed, blood cultures are often negative with invasive candidiasis, as the window of opportunity is short and may be missed. As shown in murine models, it is easy to miss a narrow window of candidemia, leading to false-negative blood cultures in clinical practice.14,15 Mouse model studies also have found that the window of candidemia is very short in disseminated candidiasis as a lethal IV dose of C albicans disappeared from blood within 48 hours of postinoculation.15 The biomarker of serum procalcitonin is a great diagnostic resource for the elimination of a likely bacterial sepsis, and conversely, the early suspicion of a fungemia, as serum procalcitonin would typically be elevated in a bacterial but not a fungal septicemia.16 The average cost per test is only about $30, and we recommend testing for serum procalcitonin as well as monitoring of serum lactate levels in cases of nonresponding septicemia.
The C albicans in this case may have been introduced hematogenously from the amputation site or through an ascending cystitis, or possibly have been derived from commensal flora in the GI tract. The iron supplementation provided to the patient may have promoted the growth and virulence of the candida; studies have shown that the kidneys assimilate increased levels of iron during disseminated candidiasis thus providing a more favorable site for colonization.17The presence of C albicans in a single collection of sputum or urine does not ordinarily indicate infection in an immunocompetent individual. Estimation of serum procalcitonin, a biomarker for bacterial infection and sepsis, might be useful if negative, for turning attention to a nonbacterial (such as, candida) source as the causative agent.18
Conclusion
C albicans can rarely cause disseminated disease in nonimmunocompromised critically ill patients. Low serum procalcitonin levels in a septic patient might indicate nonbacterial cause such as candidiasis. Even with disseminated candidiasis, blood cultures may remain negative.
