Evaluation of a commercial PCR test for the diagnosis of dermatophyte nail infections. Issue 1 (January 2015)

• Record Type: Journal Article
• Authors: Spiliopoulou, Anastasia; Bartzavali, Christina; Jelastopulu, Eleni; Anastassiou, Evangelos D.; Christofidou, Myrto
• Is Part Of: Journal of medical microbiology. Volume 64:Issue 1(2015)
• Publication Date: 2015-01
• Subjects: Medical microbiology -- Periodicals; 616.9041
• DOI: 10.1099/jmm.0.079962-0
• Languages: English
• ISSNs: 0022-2615

Abstract

Abstract : Tinea unguium, known as onychomycosis, is a dermatophyte infection of nails with worldwide distribution. Conventional methods for detecting fungi in nail specimens are either non-specific (microscopy) or insensitive (culture). PCR has been used to improve sensitivity in detecting the causative fungi in nail specimens from patients with suspected onychomycosis. Results of a commercial multiplex PCR for the detection of dermatophytes, especially Trichophyton rubrum (the main dermatophyte implicated), as compared to conventional methods are presented. A total of 418 nail scrapings obtained from dermatological outpatients were handled in the Laboratory of Microbiology between May 2010 and May 2013. Among them, multiplex PCR detected 126 (30.1 %) dermatophyte-positive samples, whereas culture revealed 44 (10.5 %). Direct microscopy revealed 63 (15.1 %) positive specimens. T. rubrum was identified in 116 out of 126 (92 %) positive PCR samples and 40 out of 44 (91 %) dermatophyte-positive cultures. Implementation of PCR increased species-specific detection of dermatophytes by 21.1 %, leading to a threefold increase as compared to culture alone. Multiplex PCR offers a time-saving diagnostic tool for tinea unguium and augments laboratory assistance to clinical evaluation for proper treatment. Abbreviations: 95 % CI, 95 % confidence interval; DOR, diagnostic odds ratio; LR−, negative likelihood ratio; LR+, positive likelihood ratio; NND, number needed to diagnose; NPV, negative predictive value; PPV, positive predictive value.