LED fluorescence microscopy in the diagnosis of tuberculosis: Fading and restaining of smears for external quality assessment.
Blinded rechecking is a method proposed for external quality assurance (EQA) of auramine-stained acid-fast bacilli (AFB) smears using fluorescence microscopy (FM), however, this procedure is not well developed and slides fading over time could compromise its implementation. Since bleaching of fluorescent molecules involves temperature-dependent chemical reactions, it is likely that low temperatures could slow down this process. We stored auramine-stained slides under different environmental conditions, including -20°C, and examined them over time. The slides stored in all the environments faded. At -20°C, fading was not reduced in relation to room temperature. Restaining and re-examining smears after five months showed that the slides containing saliva and storage at -20°C were associated with failure in AFB reappearance. In conclusion, the practice of freezing slides until they are viewed should be discouraged as it has a negative effect on blinded rechecking by reducing reading concordance after restaining. Specimen quality should be considered when interpreting FM-EQA results.
Dirección de Bioquímica de la Municipalidad de Rosario, Rosario, Santa Fe, Argentina.
Sonia
S
Allassia
Laboratorio de Tuberculosis, Hospital San Roque, San Salvador de Jujuy, Jujuy, Argentina.
Mónica
M
Aranibar
Dirección de Bioquímica de la Municipalidad de Rosario, Rosario, Santa Fe, Argentina.
Mónica
M
Boutonnet
Dirección de Bioquímica de la Municipalidad de Rosario, Rosario, Santa Fe, Argentina.
Viviana
V
Caserío
Laboratorio de Tuberculosis, Hospital San Roque, San Salvador de Jujuy, Jujuy, Argentina.
Ana Alicia
AA
Etchart
Dirección de Bioquímica de la Municipalidad de Rosario, Rosario, Santa Fe, Argentina.
Sandra
S
Fajardo
Laboratorio de Tuberculosis, Hospital F.J. Muñiz, CABA, Argentina.
Mónica
M
García
Laboratorio de Tuberculosis, Laboratorio Central de Salud Pública, Resistencia, Chaco, Argentina.
Noemí
N
Gomez
Laboratorio de Tuberculosis, Laboratorio Central de Salud Pública, Resistencia, Chaco, Argentina.
Alba Marisa
AM
Gunia
Laboratorio de Bacteriología, Hospital Interzonal General de Agudos «Evita», Lanús, Buenos Aires, Argentina.
María Virginia
MV
Gustincic
Laboratorio de Tuberculosis, Hospital San Roque, San Salvador de Jujuy, Jujuy, Argentina.
Viviana
V
Izquierdo
Laboratorio de Tuberculosis, Laboratorio Central de Salud Pública, Resistencia, Chaco, Argentina.
Arnaldo Andrés
AA
Jara
Dirección de Bioquímica de la Municipalidad de Rosario, Rosario, Santa Fe, Argentina.
Graciela
G
Kozicky
Laboratorio de Tuberculosis, Hospital F.J. Muñiz, CABA, Argentina.
Mario
M
Matteo
Dirección de Bioquímica de la Municipalidad de Rosario, Rosario, Santa Fe, Argentina.
Carlos
C
Pellegrini
Laboratorio de Tuberculosis, Laboratorio Central de Salud Pública, Resistencia, Chaco, Argentina.
Silvia
S
Pellegrino
Laboratorio de Bacteriología, Hospital Interzonal General de Agudos «Evita», Lanús, Buenos Aires, Argentina.
Sebastián
S
Pérez Catalán
Laboratorio de Tuberculosis, Hospital F.J. Muñiz, CABA, Argentina.
Susana
S
Poggi
Laboratorio de Tuberculosis, Laboratorio Central de Salud Pública, Resistencia, Chaco, Argentina.
Carina
C
Sacramone
Laboratorio de Bacteriología, Hospital Interzonal General de Agudos «Evita», Lanús, Buenos Aires, Argentina.
Gabriela María
GM
Santiso
Laboratorio de Tuberculosis, Hospital F.J. Muñiz, CABA, Argentina.
Alejandro
A
Souto
Laboratorio de Bacteriología, Hospital Interzonal General de Agudos «Evita», Lanús, Buenos Aires, Argentina.
Ana María
AM
Togneri
Laboratorio de Bacteriología, Hospital Rawson, Córdoba, Argentina.
Lidia
L
Wolff
Departamento Diagnóstico y Referencia, Instituto Nacional de Enfermedades Respiratorias «Emilio Coni», ANLIS «C.G. Malbrán», Santa Fe, Argentina.
Sandra
S
Vilche
Departamento Diagnóstico y Referencia, Instituto Nacional de Enfermedades Respiratorias «Emilio Coni», ANLIS «C.G. Malbrán», Santa Fe, Argentina.
Daniel
D
Eletti
Departamento Diagnóstico y Referencia, Instituto Nacional de Enfermedades Respiratorias «Emilio Coni», ANLIS «C.G. Malbrán», Santa Fe, Argentina. Electronic address: suimaz@yahoo.com.
María Susana
MS
Imaz
D001118:Argentina; D001576:Benzophenoneidum / Q000032:analysis / Q000528:radiation effects*; D015925:Cryopreservation; D005240:Feasibility Studies; D005456:Fluorescent Dyes / Q000032:analysis / Q000528:radiation effects*; D006801:Humans; D008029:Lighting; D008856:Microscopy, Fluorescence / Q000295:instrumentation / Q000379:methods*; D015588:Observer Variation; D038761:Photobleaching; D011237:Predictive Value of Tests; D011309:Preservation, Biological / Q000379:methods; D011785:Quality Assurance, Health Care / Q000379:methods*; D015203:Reproducibility of Results; D016037:Single-Blind Method; D013183:Sputum / Q000382:microbiology*; D013194:Staining and Labeling / Q000379:methods*; D013696:Temperature; D014376:Tuberculosis / Q000175:diagnosis*
D005456:Fluorescent Dyes; D001576:Benzophenoneidum
Evaluación externa de calidad; External quality assessment; LED fluorescence microscopy; Microscopía de fluorescencia LED; Tuberculosis