Reliability of cord formation in BACTEC 12B/13A media for presumptive identification of Mycobacterium tuberculosis complex in laboratories with a high prevalence of Mycobacterium tuberculosis.
A total of 1208 positive BACTEC vials were examined for the presence or absence of serpentine cording. A very high (92.9%) rate of laboratory prevalence was obtained for Mycobacterium tuberculosis complex. The sensitivity, specificity, positive and negative predictive values of this test were 92.7%, 95.3%, 99.6% and 50.0%, respectively. It was concluded that testing cord formation in laboratories that have a high prevalence of Mycobacterium tuberculosis complex is an exceptionally reliable method for preliminary reporting of cording-positive cases; however, for cording-negative cases, preliminary reports based solely on cord formation are not reliable. It was also observed that the length of the incubation period has a significant effect on cord formation. Incubation periods of 4 days or less are not sufficient to determine noncording in smears prepared from positive BACTEC vials.
Köksalan
O K
OK
Department of Genetics, Institute for Medical Experimental Research (DETAE), Istanbul University, Istanbul, Turkey. okkoksalan@hotmail.com
Aydin
M D
MD
Eraslan
S
S
Bekiroglu
N
N
D001431:Bacteriological Techniques / Q000379:methods*; D003311:Cord Factors / Q000096:biosynthesis*; D003470:Culture Media / Q000378:metabolism*; D006801:Humans; D007753:Laboratories; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification* / Q000378:metabolism*; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D014376:Tuberculosis / Q000175:diagnosis
D003311:Cord Factors; D003470:Culture Media