is a gram-positive organism that grows

slowly with branching filaments. It is a commensal

but becomes invasive. Macroscopically it appears as

yellow (sulfur) granules less than 1 mm in diameter.

Microscopically, they are gram-positive mycelial filaments

surrounded by a sheath of eosinophilic matter, which

imparts a club-shaped appearance to the ends of these

filaments.

Nocardia asteroides

These are like A. israelii but lack the clubbed ends. The

filaments are gram-positive, bacilliform in shape and in

some stains are partially acid fast. It may, however, be a

saprophyte in the upper respiratory tract. Its repeated

presence is diagnostic of pulmonary nocardiosis.

Cryptococcus neoformans

Direct examination with India ink is advocated. The

organism appears as a single budding blastospore, 2 to 20 µ

in diameter and is surrounded by a capsule from 3 to 5 µ in

diameter.

Histoplasma capsulatum

Sputum staining with Wright’s/Giemsa’s stain reveals

macrophages with characteristic intracellular small yeast

cells in the cytoplasm.

Coccidioides immitis

Examine sputum by wet direct mounts. The organism

appears as a spherule, 5–200 µ in diameter and is filled

with endospores. In the chronic cavity, hyphae may be

seen.

Blastomyces dermatidis

Infection beginning from lungs may spread hematogenously. In direct wet mounts, the organisms appear

as 8–15 µ diameter spherules without a capsule. Budding

may be seen with a characteristic sputum. No mycelium

occurs in sputum.

Candida albicans

It is a throat commensal but overgrows with excessive use

of antibiotics and immunosuppressants and becomes

pathogenic (keep in mind that they can grow very well

on sputum in vitro also). The report should indicate the

number of organisms seen per field. On direct mount,

they appear as 4µ diameter, thin-walled organisms

singly, in pairs, or in small clusters. Budding forms and

pseudomycelia may be seen. The organisms stain intensely

positive with Gram’s stain.

Aspergillus fumigatus

These are like C. albicans, the organism appears often as a

sputum contaminant.

Phycomycetes

Mucormycosis rarely causes pulmonory lesions and occur

more commonly in diabetics. Direct wet mount may show

huge (15 µ diameter) aseptate hyphae. Isolation on culture

is a must.

Bronchial Asthma

The sputum is usually white and mucoid and contains no

blood or pus unless an underlying infection is present.

Various findings seen are:

1. Eosinophilia: Sputum has eosinophilic staining

properties (attributed to increased accumulation of

serum proteins), not seen in chronic bronchitis.

2. Bronchial epithelial cells: These often occur singly and

show hydropic change with poorly defined original

morphology. During acute phases, these cells gather

in larger clusters, display a vacuolated cytoplasm with

ciliated border—known as Creola bodies. In addition,

one may see hypersecretory goblet cells singly/

clustered.

Sputum Examination 409

3. Charcot-Leyden crystals: Seen almost only in the

sputum of bronchial asthma cases. The crystals are

colorless, pointed hexagons and variable in size

(may look needle shaped). These are derived from

disintegration of eosinophils, hence they stain strongly

with eosin.

4. Blood cells: Mostly eosinophils are seen, infection

brings with it a neutrophilic response. Monocytes and

histiocytes appear in significant numbers during the

recovery phase.

5. Creola bodies: Almost exclusively seen in sputum of

bronchial asthma cases. Their appearance is a poor

prognostic sign.

6. Curschmann’s spirals: These are characteristic of

bronchial asthma sputum but may be seen in other

respiratory disorders. Macroscopically, they can

sometimes be recognized by the naked eye and appear

as yellow-white, mucoid, wavy threads frequently

coiled into little balls. Their length may exceed

1.5 cm. Microscopically, they show a central thread

around which mucus is wrapped, supported by a fibril

network.

Bronchiectasis

The production of mucopurulent sputum is one of

the cardinal signs of bronchiectasis and the amount

expectorated varies with the posture. Morning cough is

typical. Characteristically, the sputum is putrid, gray green

in color (50–250 mL/day), at times blood tinged. On sitting,

the sputum separates into three layers: (i) upper frothy

layer, which later subsides, (ii) a middle turbid mucous

layer and (iii) a bottom layer of pus cells and various

organisms. The microscopic examination of bottom layer

discloses bronchial epithelial cells, fatty crystals, bacteria

and occasionally Dittrich’s plugs. When crushed, they emit

a foul odor.