Abstract:
This study aimed to determine the frequency of Nocardia species among
tuberculous patients.
It is a cross-sectional laboratory-based study in which sputum samples
were collected from patients attending Abu-Anga Teaching Hospital, El
Shaab Teaching Hospital and the Tuberculosis Reference Laboratory at
the national Health Laboratory in Khartoum, Sudan, during the period
from January to March 2010. Patients were consented and informed. All
sputum samples that showed AFB-positive results were included.
Two tubes of the Lowenstein-Jensen medium were inoculated with 20μl
of the neutralized sputum sample that was obtained from the digestion
and decontamination. One of the tube contained pyruvic acid to isolate
Mycobacterium bovis if encountered. All the cultures were incubated at
37 ̊C.
158 samples showed the growth of Mycobacterium tuberculosis and
showed the appearance of AFB when stained again (indirect smear) with
Ziehl-Neelsen for confirmation.
Seven (4.2%) of the LJ slopes revealed the growth of small orange
filamentous colonies, which were tentatively considered to be Nocardia.
biochemical tests showed that all the strains were catalase positive. Five
isolates (71%) grow at 45 ̊C and were positive for rhaminose. four
isolates (57%) showed the stander patterns of mycolic acid components
when using thin layer chromatographic technique, and also were positive
for urea. Three isolates (42%) were positive for tyrosine, starch and
citrate. Two isolates (28%) were positive for xanthine. One isolate (14%)
was positive for casein and sorbitol, whilst all the isolates were negative
for manitol and salicin.
These results showed significant numbers of isolates (4.2%) were found
to having phenotypic properties typical of members of the genus
Nocardia, and revealed clearly the importance of conventional methods
in the diagnosis of pulmonary patients especially if there is other invader
like Nocardia species.
