Diplococcus means
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Diplococcus - Definition and Meaning
Diplococcus (plural: diplococci) is a term used in microbiology to describe cocci (spherical bacteria) that characteristically appear in pairs after cell division. The name comes from Greek:
- "diplo" = double/twofold
- "coccus" = berry/grain (referring to the spherical shape)
Key Points
Morphology: After a coccus divides, instead of separating completely, the two daughter cells remain attached to each other, forming a pair. This paired arrangement is called a diplococcus.
Classic examples from medical microbiology:
| Organism | Description |
|---|---|
| Neisseria gonorrhoeae | Gram-negative intracellular diplococcus; causes gonorrhea |
| Neisseria meningitidis | Aerobic gram-negative diplococcus; causes meningococcemia |
| Streptococcus pneumoniae | Gram-positive diplococcus (lancet/flame shaped); causes pneumonia |
| Moraxella catarrhalis | Gram-negative aerobic diplococcus; causes respiratory infections |
Characteristic shape: The individual cocci in Neisseria species are kidney bean-shaped (reniform), and when they occur in pairs, the flat or concave sides face each other - giving the classic "coffee bean" appearance.
Clinical Significance
Identifying diplococcal morphology on Gram stain is an important rapid diagnostic clue:
- Gram-negative intracellular diplococci in a urethral or cervical smear = N. gonorrhoeae until proven otherwise
- Gram-positive lancet-shaped diplococci in sputum = S. pneumoniae (pneumococcus)
Sources: Jawetz Melnick & Adelberg's Medical Microbiology 28e; Harrison's Principles of Internal Medicine 22e
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