Chronic Bronchitis

This may be catarrhal or cellular. Macroscopically the

sputum is tenacious, white and mucoid in appearance.

Intercurrent infections make it purulent yellow-green in

color. The average volume expectorated is about 60 mL/

day. A decreasing volume implies improvement. In early

chronic bronchitis, large numbers of histiocytes and

monocytes indicate a stable phase, during exacerbation

these cells disappear. When entering remission, these cells

reappear. Leukocytes and epithelial cells are increased

during active disease and diminished in number with

recovery. Presence of necrotic tissue/elastic fibers

indicates abscess formation or bronchiectasis. Examination of the Gram’s stain usually reveals the presence

of mixed organisms. Active phase is accompanied by

raised sputum LDH levels. When bacterial resistance to

antibiotic therapy is developing, increased LDH activity

may be observed before clinical deterioration. Therefore,

appropriate changes in antibiotics may be made sooner

rather than waiting for culture or clinical signs. In

addition, DNA levels also rise during infections. Levels fall

as improvement is noted.

Lung Abscess

Only when it ruptures into a bronchus—it leads to

sputum production. The etiologic agent usually isolated

are Klebsiella, Haemophilus, Staphylococcus aureus,

Streptococcus hemolyticus. Following rupture, a large

amount of bloody, creamy, foul smelling pus is suddenly

and violently expectorated. More often than not, mixed

organisms are present. A search for tubercle bacilli or

malignant cells must also be made.

Pneumonia

Early diagnosis can be established by a Gram’s stain of the

sputum. Sputum should be homogenized for a more even

distribution of pathogenic organisms on Gram’s stain.

Of the gram-positive pneumonias, the main pathogen is

Diplococcus pneumoniae, rarely are staphylococci and

streptococci involved.

In pneumococcal pneumonia, the sputum characteristics change with the stage of the disease. Early

lobar pneumonia sputum is scanty and transparent

with occasional blood flecks. In red hepatization stage

the sputum becomes rusty red in color, tenacious

and mucopurulent. Microscopically, many intra- and

extracellular organisms, epithelial cells, leukocytes and

red cells are seen. During resolution stage, the sputum

becomes more abundant, less tenacious and assumes the

appearance as seen in chronic bronchitis. Reappearance

of rusty character should indicate further progression or

involvement of the opposite lung. Daily sputum Gram’s

stains should be performed on these patients for two

reasons: (i) to follow the effect of treatment, and (ii) to rule

out secondary infection.

In staphylococcal pneumonia, a yellow purulent,

voluminous sputum is present. On Gram’s stain, large

numbers of staphylococci and neutrophils are seen.

Gram-negative pneumonias are often caused by

Klebsiella, Haemophilus, Pseudomonas and Escherichia

coli. With the exception of foul green sputum seen in

410 Concise Book of Medical Laboratory Technology: Methods and Interpretations Pseudomonas infections, no classic macroscopic findings

are present in these sputums. As a group, sputums in the

various gram-negative pneumonias are purulent and

foul smelling. Putrid sputums may be associated with

anaerobic organisms and should be cultured accordingly.

In Gram’s stain, Haemophilus is often missed as safranin

does not stain it well but methylene blue stain permits

easier recognition of H. influenzae.

Pneumoconiosis

1. In anthrasilicosis angular black granules will be both

intra- and extracellular but are not pathognomonic as

they can be seen in urban dwellers and smokers.

2. In asbestosis, dumbbell-shaped asbestos needles in

clusters are diagnostic. Numerous multinucleated

giant cells and histiocytes may also be seen.

3. In silicosis the particles are detected by polarization

microscopy. The crystals appear sharp, elongated, and

fragmented. Numerous neutrophils, macrophages,

and multinucleated giant cells may be observed.

4. In byssinosis also, polarized light can be used to

demonstrate the crystals. They appear as rectangular,

prism-shaped crystals that shine brightly with

polarized light.

Pulmonary Embolism

Pulmonary embolism causing infarction reveals bright

red blood in a very tenacious, mucoid background. As the

infarction resolves, the sputum becomes progressively

darker in color. Microscopic examination shows

erythrocytes, macrophages with denatured hemoglobin

in the cytoplasm.