Comparison of the sodium hydroxide specimen processing method with the C18-carboxypropylbetaine specimen processing method using independent specimens with auramine smear, the MB/BacT liquid culture system, and the COBAS AMPLICOR MTB test.
A study was performed to diagnose tuberculosis by smear, culture, and nucleic acid amplification. The study was comprised of two independent arms. Each arm used a different specimen processing method; in one arm, all specimens were processed with N-acetyl-l-cysteine-sodium hydroxide, and in the other arm, all specimens were processed with C(18)-carboxypropylbetaine and lytic enzymes. In each arm, all processed sediments were split for analysis by auramine smear, by culture using the MB/BacT liquid culture system and solid media, and by nucleic acid amplification using the COBAS AMPLICOR MTB test. In the N-acetyl-l-cysteine-sodium hydroxide arm, 1,468 specimens were analyzed: 65 were smear positive; 88 and 42 were culture positive for Mycobacterium tuberculosis and nontuberculous mycobacteria, respectively; and 103 were PCR positive. Relative to cultures positive for M. tuberculosis, the sensitivity and specificity of the smear were 68.2% and 99.6%, respectively, and those of PCR were 75.0% and 97.3%, respectively. In the C(18)-carboxypropylbetaine study arm, 1,423 specimens were analyzed: 44 were smear positive; 82 and 31 were culture positive for M. tuberculosis and nontuberculous mycobacteria, respectively; and 91 were PCR positive. The sensitivity and specificity of the smear were 48.8% and 99.7%, respectively, and those of PCR were 78.0% and 98.0%, respectively. When the two arms were compared, C(18)-carboxypropylbetaine specimen processing significantly increased the number of smear-negative and culture-positive specimens and significantly increased the PCR sensitivity among this same group of specimens while at the same time significantly reducing the inhibition rate.
Padilla
Eduardo
E
Servei de Microbiología, Hospital Universitari Germans Trias i Pujol, Carretera de Canyet s/n, 08916 Barcelona, Spain. epadilla@ns.hugtip.scs.es
Manterola
José M
JM
González
Victoria
V
Thornton
Charles G
CG
Quesada
M Dolores
MD
Sánchez
M Dolores
MD
Pérez
Miguel
M
Ausina
Vicente
V
D000890:Anti-Infective Agents; D001431:Bacteriological Techniques; D001576:Benzophenoneidum; D001622:Betaine / Q000031:analogs & derivatives* / Q000494:pharmacology; D003470:Culture Media; D006801:Humans; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification*; D021141:Nucleic Acid Amplification Techniques / Q000379:methods; D016133:Polymerase Chain Reaction / Q000379:methods; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D012972:Sodium Hydroxide / Q000494:pharmacology*; D013048:Specimen Handling / Q000379:methods*; D013183:Sputum / Q000382:microbiology; D014376:Tuberculosis / Q000175:diagnosis* / Q000382:microbiology
D000890:Anti-Infective Agents; C114390:C(18)-carboxypropylbetaine; D003470:Culture Media; D011933:Reagent Kits, Diagnostic; D001576:Benzophenoneidum; D001622:Betaine; D012972:Sodium Hydroxide