Prevalence of Nocardia Species among Patients with Chronic Pulmonary Infection in Khartoum State

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.