How are culture specimens collected for diagnosis of disseminated gonococcal infection (DGI)?

Updated: Sep 07, 2018
  • Author: Brian Wong, MD; Chief Editor: Pranatharthi Haran Chandrasekar, MBBS, MD  more...
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Answer

In patients who may have DGI, all possible mucosal sites should be cultured (eg, pharynx, cervix, urethra, rectum), as should blood and synovial fluid (in cases of septic arthritis). Three sets of blood cultures should also be obtained. Specimens from any mucosal site should be inoculated immediately in selective media for gonorrheal organisms, such as modified Thayer-Martin, or on chocolate agar at room temperature, which should be incubated in an enriched carbon dioxide environment. The growth of typical oxidase-positive colonies that consist of gram-negative diplococci strongly suggests gonorrhea.

Samples from normally sterile sites (eg, blood, cerebrospinal fluid [CSF], synovial fluid) should be plated on nonselective and broth mediums. On the other hand, rectal and pharyngeal specimens, locations where commensal Neisseria may be present, should be inoculated onto selective medium only.

Synovial fluid aspirations in patients with septic arthritis usually yield greater than 50,000 leukocytes/µL, while synovial fluid culture is variably positive. Blood cultures, at this point, are often negative.

Gram stain and culture of vesicular or pustular skin lesions were found to have a diagnostic yield of less than 5%. Immunofluorescent techniques may be used to achieve better results.


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