Slide 1. Haemophilus influenzae
These small, pleomorphic gram-negative bacteria range in shape from round (cocci) to short, thin rods (bacilli); hence the bacteria are called “coccobacilli.” In specimens from patients with pneumonia caused by Haemophilus influenzae, both neutrophils and bacteria are usually plentiful. However, if examination of the slide is not thorough, the coccobacilli may be inconspicuous in the background of pink-staining mucus. Other organisms, such as Eikenella corrodans or Bacteroides species, are also pleomorphic gram-negative coccobacilli; but they rarely cause pneumonia.
These small, pleomorphic gram-negative bacteria range in shape from round (cocci) to short, thin rods (bacilli); hence the bacteria are called “coccobacilli.” In specimens from patients with pneumonia caused by Haemophilus influenzae, both neutrophils and bacteria are usually plentiful. However, if examination of the slide is not thorough, the coccobacilli may be inconspicuous in the background of pink-staining mucus. Other organisms, such as Eikenella corrodans or Bacteroides species, are also pleomorphic gram-negative coccobacilli; but they rarely cause pneumonia.