Pulmonary Nocardiosis; Similarity to Tuberculosis (A Bacteriological and Proteomics Study)

Objective: The aims of the present study were to decide the occurrence of nocardia spp. among Sudanese patients suspected with tuberculosis and to investigate all proteins expressed by the genome of Nocardia africana (formerly isolated from patients with pulmonary infection misdiagnosed as MDR and their structures and functions compared to Mycobacterium tuberculosis.
Materials and Methods: Three hundred and twenty-nine patients, presented with pulmonary infection were included in this study. Those patients were examined for the presence of acid- fast bacilli. Two tubes of Lownstein- Jensen (L.J) medium were inoculated with 20 ml of the neutralized sputum sample. All cultures were incubated at 37°C for 8 weeks before being discarded. Phenotypic characterizations were performed. For nocardia proteom poly acrylamide gele lectrophoresis (PAGE)-based analyses of the four nocardia strains N. farcinica SD1828, N. africana SD 925, and N. asteroides N317 are discussed. In-gel tryptic digestion of these isolates was also performed, then the resulting peptides were introduced to MALDI-TOF peptide mass fingerprints were searched using MASCOT software.
Results: Ten isolates showed rapid growth pattern within 2-3 days after inoculation, further conventional methods suggested that all these isolates were belonging to the family nocardiacea. Two Dimentional Poly Acrylamide Gel Electrophoresis (2D-PAGE) using pH strips 3-10 revealed that the soluble proteins were visible in a much smaller pI range. All strains exhibited similar protein distributions. A similarity analysis revealed that mycobacterium sequences are of high relevance for the investigated strains.
Conclusions: Nocardia revealed considerable occurrence among patients with pulmonary infections (3.3%) giving clinical symptoms similar to those occur by M. tuberculosis infection, this may be due to similarities in functional proteins expressed by their genomes. This finding suggested that pulmonary nocardiosis might occur in patients who suffer from chronic lung disease in Sudan. It is important, therefore, that clinicians in Chest Units should consider this condition, especially when patients with respiratory infections fail to respond to antitubercular therapy.