Galactomannan and mannan antigens and anti-mannan antibodies detection for the diagnosis of invasive aspergillosis and candidiasis in liver transplant recipients

Abstract number: r2076

Machetti  M., Di Domenico  S., Pellizzari  A., Furfaro  E., Valente  U., Viscoli  C.

Objectives: 

Fungal infections in liver transplanted patients may decrease the survival rate at 120 days after transplant from 90% to 65%. Hence it is important a rapid diagnosis to allow an early antifungal therapy. We studied the utility of galactomannan (GM), mannan (MAN) and antiMAN antibodies detection for the rapid diagnosis of invasive aspergillosis (IA) and candidiasis in liver transplant recipients.

Methods: 

Four hundred and sixty-five serum samples were collected from 46 liver transplanted patients, during the post-transplant hospitalization in the intensive and sub-intensive care unit. After a collection period of 13 months, samples were analysed with the Platelia Aspergillus, Platelia Candida Ag and Platelia Candida AB tests (BIO-RAD). Positivity cut-off for GM detection was a GM index (sample OD/control cut-off OD) >=0.7. For MAN detection the test was positive if MAN concentration was >=0.5 ng/ml, while for antiMAN assay the test was positive if antibodies content was >=10 arbitrary units (as defined by the manufacturer).

Aspergillus results: 

No cases of IA or Aspergillus colonization were found in the 46 pts. However 3 of them tested positive for GM and they were considered as false positive cases.

Candida results: 

MAN and/or antiMAN test were positive in 20 of 46 pts. Within the first 100 days post transplant 98.5% of MAN and 100% of antiMAN test were positives, vs. 93% of MAN and 84% of antiMAN negative results.

Candida infections: Five pts. had probable candidiasis (2 with positive cultures from SwanGanz catheter and 3 with Candida colonisation index >=0.5). Three of 5 infected patients tested positive for MAN and/or antiMAN, while 17 of 41 non-infected pts. were positives for antigens and/or antibodies assays. Cumulative sensitivity and specificity of the 2 Candida tests were 60% and 58.5%.

Candida colonisation: 

Twenty-six of 46 patients (56.5%) had Candida colonization (included the 5 pts. with probable candidiasis) and 14 of 26 colonized patients (53.8%) were positive for MAN and/or antiMAN test, vs. 6 of 20 between the non-colonized patients (30%). Moreover the time of first colonization and first positivity of the two Candida tests were almost all within 20 days after transplantation.

Conclusions: 

Due to the absence of IA, only the specificity (93%) was valuable for the GM detection. As for Candida assays, MAN and antiMAN tests performed poorly and Candida colonization also seems actively influence the detection of Candida antigens and antibodies.