USE OF MICROSCOPIC MORPHOLOGY IN SMEARS PREPARED FROM RADIOMETRIC CULTURES FOR PRESUMPTIVE IDENTIFICATION OF MYCOBACTERIUM-TUBERCULOSIS COMPLEX, MYCOBACTERIUM-AVIUM COMPLEX, MYCOBACTERIUM-KANSASII, AND MYCOBACTERIUM-XENOPI
J. Gonzalez et al., USE OF MICROSCOPIC MORPHOLOGY IN SMEARS PREPARED FROM RADIOMETRIC CULTURES FOR PRESUMPTIVE IDENTIFICATION OF MYCOBACTERIUM-TUBERCULOSIS COMPLEX, MYCOBACTERIUM-AVIUM COMPLEX, MYCOBACTERIUM-KANSASII, AND MYCOBACTERIUM-XENOPI, European journal of clinical microbiology & infectious diseases, 17(7), 1998, pp. 493-500
The aim of this study was to assess the feasibility of a method for pr
esumptive identification of mycobacteria? based on the morphology in s
mears prepared from radiometric Bactec-positive cultures (Becton Dicki
nson, USA) and to select the appropriate DNA probe (AccuProbe; Gen Pro
be, USA). The smear morphology of acid-fast bacilli was evaluated in 4
68 positive cultures from clinical samples: 313 Mycobacterium tubercul
osis complex, 67 Mycobacterium avium complex, 32 Mycobacterium kansasi
i, 49 Mycobacterium xenopi, and seven Mycobacterium gordonae. The sens
itivity and specificity for various morphological patterns were as fol
lows: cord formation for Mycobacterium tuberculosis complex 90% and 10
0%, respectively; striped bacilli for Mycobacterium kansasii, 66% and
99%; sea urchin for Mycobacterium xenopi, 96% and 99%; short bacilli f
or Mycobacterium avium complex, 61% and 99%; fine-striped bacilli asso
ciated with Mycobacterium avium complex from blood samples, 33% and 98
%. This criterion was applied in the selection of a suitable DNA probe
for the identification of 178 cultures. The correct probe was selecte
d in 98%, 97%, and 72% of cultures, respectively, for Mycobacterium tu
berculosis complex, Mycobacterium avium complex, and Mycobacterium kan
sasii. The observation of acid-fast bacilli morphology in radiometric
cultures is a rapid and cost-efficient method for presumptive identifi
cation of common clinical isolates of mycobacteria.