Cryptococcosis in kidney transplant recipients: Current understanding and practices

Table 1 Modalities for the diagnosis of post-transplant cryptococcosis

Method	Advantages	Disadvantages
Direct microscopic examination	Cryptococcus is identified as narrow budding encapsulated yeasts after mixing sample with India ink.	Direct microscopic examination
Culture	Identify the species and susceptibility patterns	Time consuming. More than 1 wk must elapse for fungal growth to occur
Histopathology	Gomori methenamine silver, and periodic acid-Schiff are used to detect Cryptococcus that appears as narrow-based budding yeasts (4-10 μm), usually surrounded by thick capsules in the lung tissue	Histopathology
Antigen detection	Inexpensive point-of-care testing, simple, cheap and rapid diagnosis in developing country, high sensitivity and specificity	Isolated pulmonary cryptococcal infection is usually associated with false negative serum CrAg, probably because of the low fungal burden outside the lung or the capsule-deficient strain of Cryptococcus. One must be aware of the prozone effectwhile interpreting these tests
Molecular detection	Required in specific situations where other diagnostic tools have failed to confirm a diagnosis of cryptococcosis, highly specific (almost 100%)	Expensive and not routinely available

CrAg: Cryptococcal antigen.