Presumptive diagnosis of pulmonary nocardiosis: value of sputum microscopy

Abstract

Three hundred samples of sputum from patients suffering from various forms of pulmonary disorders were homogenized by pancreatic digestion, examined microscopically and cultured on brain heart infusion agar, trypticase soy agar, in brain heart infusion broth, trypticase soy broth and McClung's carbon-free broth. Several elements of varying morphological forms, believed to be from aerobic actinomycetes or nocardias, were observed in 16 cases. Six strains of Nocardia asteroides, one N. brasiliensis, eight of Rhodococcus species and one Micromonospora were isolated and studied at various stages of growth. Several nocardial and rhodococcal elements closely resembling those observed in the Gram-stained sputa were found. It is suggested that some of those in the sputum were from nocardias and that their appearance in sputum, as seen from the Gram-stained slide, when combined with clinical symptoms can serve for a presumptive diagnosis of pulmonary nocardiosis pending a more definitive identification by a specialized laboratory.

Evidence for the pathogenic role of Rhodococcus species in pulmonary diseases

“…There was no true branching. The cell wall sugars were galactose and arabinose and physiochemical reactions conformed to those already reported (Osoagbaka & Njoku-Obi 1987). Eight strains of Rhodococcus species were isolated.…”

“…Some of the peculiar elements seen in stained direct sputum smears of the patients involved were as reviously reported by Osoagbaka & Njoku-Obi (1987). In some of the smears several rod-like, sometimes curved or twisted Grampositive elements, some showing weak acidfastness by the Kinyoun's cold method but negative by the normal ZN staining method, were present among other micro-organisms (Figs 1 and 2).…”

“…Organisms isolated were identified to generic level with conventional and special tests used for nocardias and related taxa. These included: the ability to grow at 450°C; degradation of casein, xanthine, hypoxanthine, adenine or tyrosine and urea; growth in the presence of lysozyme and in 0.4% gelatin; utilization of adonitol, cellobiose, erythritol, mellibiose, adonitol and fructose as carbon sources for energy and growth; formation of acid from fructose, glucose, glycerol, sorbitol, xylose, maltose, mannose, dulcitol, lactose and raffinose; arylsulphatase activity; ability to develop true branching, aerial mycelium and spores; and other tests as previously published (Berd 1973;Osoagbaka & Njoku-Obi 1987). Identification to species level was done by J.M.…”

Current Status of Nocardia Taxonomy and Recommended Identification Methods

“…The modified acid-fast smear used on direct specimens may more accurately reflect the true partially acid-fast nature of Nocardia species than do modified acid-fast stains prepared from colonial growth. From direct specimens, Nocardia may appear as beaded cells with strongly acid-fast granules within non-acid-fast or weakly acid-fast rods (18).…”

Experimental infection of chickens withNocardia asteroidesandNocardia transvalensis

“…Nocardiosis, an infection caused by aerobic actinomycetes of the genus Nocardia, has been described in humans (Conant er al., 1971;Gugnani et al, 1981;Osoagbaka & Njoku-Obi, 1987) and in other mammals (Emmons et al, 1977;Mohan, 1983;Love, 1988). Information on avian nocardiosis is limited, however, to a few reports on domestic fowl (Ainsworth & Austwick, 1973), a red-legged honeycreeper (Bergman et al, 1973), blue-winged king parrots (Ehrsham & Häuser, 1979) and a purple-throated sunbird (Parnell et al, 1982).…”