Comporison of the culture and non-culture methods and development of an ELISA technique for the determination of chitin antigen in the diagnosis of systemic mycoses

The diagnosis of systemic fungal infection is still be difficult andproblematic. Although the culture is the gold standard among the conventionaldiagnostic methods, it can be sometimes difficult and time-consuming.In this study, we aimed to compare the use of conventional culture with thenon culture methdos such as galactamannan assay, ß-glucan assay, andpolymerase chain reaction in the diagnosis of systemic fungal infections. On theother hand, we aimed to investigate and develop the possible usage of the chitinmeasurement by ELISA in the sera of the patients with suspected mycosis for theearly diagnosis of fungal infections.Fourty six patients with suspected fungal infections and 46 volunteerswere included in this study.Blood cultures were found positive in the seven (15.2%) of the 46 patientswith systemic fungal infections. Galactomannan antigen was found positive in 8(17.4%) samples by the Platelia Aspergillus test. ß-glucan activity wasmeasured by the FungitellTM kit and five (10.9%) samples yielded positive results.Candida DNA was found positive in six (13%) samples by real-time PCR, andAspergillus DNA in one (2.2%) sample. Chitin antigen was measured in 46 serumsamples in 1/1, 1/5, and 1/10 dilutions and was found positive in all of them.No growth was observed in the cultures of the blood samples of the controlgroup. Aspergillus and Candida DNA were also not detected, and galactomannan112and ß-glucan levels were found negative in the control group. A slight activity,however, was detected in the chitin ELISA.A statistically important correlation was found between the culture andCandida PCR results (p=0.01). We found also an important correlation betweenthe Aspergillus PCR and galactomannan ELISA results (p=0.028). A correlationwas not found between ß-glucan and Candida PCR results (p=0.060).In conclusion, we think that the use of these test in combination would beuseful in order to improve the performance of the non culture tests. Investigationof the presence the chitin antigen by ELISA would be useful for the earlydiagnosis of the funfal infections and therefore we tested the chitin level in theserum samples. However, we did not found any correlation when compared withother diagnostic methods. We think that, although the chitin assay has not beenroutinely used now, measurement of the chitin level may be useful in the futureafter appropriate optimization.Key words: PCR, Galactomannan, ß-glukan, chitin ELISA