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Sputum–Gram-Positive Bacterial Infections Send Print

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Created: Tuesday, 06 February 2007
Last update: Tuesday, 27 September 2011
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Streptococcus pneumoniae (Enlarged view)
Slide 1. Streptococcus pneumoniae (“pneumococcus”)
This is a good, adequately decolorized, sputum specimen with several neutrophils but no epithelial cells. The predominant organisms are paired, slightly elongated (“lancet-shaped”) gram-positive cocci. In sputum specimens, pneumococci are usually paired but can be found as single cocci or short chains of three or four organisms. The halos visible around many of the cocci may be the polysaccharide capsules of Streptococcus pneumoniae.
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Streptococcus agalactiae (Enlarged view)

Slide 2. Streptococcus agalactiae (group B streptococcus)
Large, round, gram-positive cocci are found singly and in pairs, chains, and clumps. The cocci are larger and rounder than pneumococci, which rarely, if ever form chains of more than four cocci in sputum. Various nonpneumococcal streptococci cannot be differentiated by their appearance on a Gram stain. When chains of streptococci overlap, they can resemble clusters of staphylococci, making differentiation of these two kinds of bacteria difficult.

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Staphylococcus aureus (Enlarged view)

Slide 3. Staphylococcus aureus
Numerous gram-positive cocci, round and large, are visible as single organisms, pairs, and grape-like clusters. The clusters strongly suggest that the organisms are staphylococci. The red strands of mucus in the background are common in good sputum specimens.

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Nocardia asteroides (Enlarged view)

Slide 4. Nocardia asteroides
Nocardia asteroides are branching, beaded, gram-positive bacilli. Actinomyces look the same, and Streptomyces species are also long, branching gram-positive rods, but usually are not beaded.

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Nocardia asteroides (Enlarged view)

Slide 5. Nocardia asteroides
When stained with a modified acid-fast technique, as this specimen is, most Nocardia are acid fast, but Actinomyces and Streptomyces species are not. The presence of branching, red rods on the blue background confirms that the organism is acid fast and thus most likely Nocardia.

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Nocardia asteroides (Labeled view)

(Labeled view)

These images are from the original published atlas: Tenover, F. C., and J. V. Hirschmann. 1990. Interpretation of Gram stains and other common microbiologic slide preparations. The UpJohn Company, Kalamazoo, Mich. Permission granted to the ASM MicrobeLibrary by Pfizer Inc.
This atlas was written to help clinicians, microbiologists, and laboratory personnel identify organisms in infected materials stained by techniques commonly used in most clinical laboratories. Please refer to the atlas' main page for more information and a guide to all of the images.
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Tags: Cell biology (255) , Microbes in humans (382)