Sensitivity of Fite-Faraco versus auramine-rhodamine in mycobacterial infection

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“…Previous literature describing the use and effectiveness of FF in NTM diagnosis is largely lacking, a gap which is partially filled by Snyder et al in the article being commented upon. 8 Its use has been documented to visualize M. ulcerans in skin samples. 21 One study that evaluated FF, ZN and PCR for skin punch biopsies of M. leprae concluded that FF had a greater sensitivity than ZN, and had the best sensitivity when combined with PCR.…”

“…However, culture can require weeks to allow for colony growth, and in Snyder et al, culture was found to be positive only 75% of the time in cases of NTM infection proven via other methods. 8 Therefore, various reflexive molecular techniques may be used in conjunction with culture for rapid species detection and subsequent identification, 38 with methods including PCR, gene probe, DNA sequencing, high-performance liquid chromatography (HPLC), and MALDI-TOF mass spectrometry. PCR uses a short, single-stranded DNA primer that allows for amplification of a specific DNA sequence, through the process of denaturing, annealing and extending.…”

“…FF also demonstrated moderate sensitivity in gastrointestinal and lymph node tissues with values of less than 50 percent. 8 Other notable findings included that, of 17 AR+ samples for which polymerase chain reaction (PCR) was also performed, only seven (41.2%) were positive by this method. In contrast, of 19 AR+ samples for which gene probe was performed, 18 (94.7%) were positive.…”

“…Of the 53 total AR+ samples included in the study, 8 (42.1%) were never identified by species, and 17% of diagnoses relied on histology alone. 8 Therefore, there is clearly a need to develop diagnostic algorithms for NTM histopathology stains to aid in accuracy and efficiency of diagnosis.…”

Remember the Fite: A Case of Cutaneous Mycobacterium fortuitum Infection

“…6 Fite staining has demonstrated slightly superior sensitivity (74.6%–43.2%) compared with ZN staining (72.7%–21%) in the detection of mycobacteria, including NTM species. 4,6–10 Although numbers in the literature are small, the sensitivity of Fite (50%; 1 of 2 cases) has been found to be superior to ZN (33%; 2 of 6 cases) for identification of M. fortuitum specifically. 4,7 Of note, Crothers et al 10 reported that ZN staining had a sensitivity of 0% for detecting fast-growing mycobacteria versus 31% for slow-growing mycobacteria ( P = 0.04).…”