Using a Madurella mycetomatis‐specific PCR on grains obtained via non‐invasive fine‐needle aspirated material is more accurate than cytology

Abstract

AbstractBackgroundEumycetoma is a chronic subcutaneous inflammatory fungal infection most often caused by the fungus Madurella mycetomatis. Using a species‐specific PCR on DNA directly isolated from grains is currently the most reliable method for species identification. However, so far, PCR has been performed on grains obtained through deep‐seated surgical biopsies, which are invasive procedures. Grains can also be obtained via ultrasound‐guided fine‐needle aspiration (US‐FNA). Here we determined the diagnostic performance of species‐specific PCRs performed on samples obtained through US‐FNA.MethodsFrom 63 patients, US‐FNA was performed to obtain eumycetoma grains; 34 patients also underwent a deep‐seated biopsy. From the grains, DNA was isolated, and one pan‐fungal and two M. mycetomatis‐specific PCRs were performed. The sensitivity and specificity were determined.ResultsOf the 63 patients who underwent US‐FNA, 78% (49/63) had evidence of eumycetoma based on cytology and 93.7% (59/63) based on species‐specific PCRs. In the 34 patients for whom surgical biopsies were performed as well, 31 patients had a positive PCR for M. mycetomatis when DNA was isolated from the deep‐seated biopsy, and 30 had a positive PCR when DNA was obtained from the US‐FNA material. This resulted in a 96.8% sensitivity, and 100% specificity with 97.1% diagnostic accuracy for PCR performed on US‐FNA.ConclusionPCR performed on the US‐FNA material has a similar sensitivity and specificity as PCR performed on deep‐seated biopsies. Therefore, when using PCR, a deep‐seated biopsy may not be necessary to obtain grains.