Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1442 page)

   Use

   This culture is used to detect enteric infection caused by
Vibrio cholerae
or related
Vibrio
species. Specimens are inoculated on the thiosulfate citrate bile sucrose (TCBS) medium, a differential and selective medium for
Vibrio
isolation. Broth enrichment using alkaline peptone water may be used to improve isolation. Colonies from routine stool culture may be screened for cytochrome oxidase–positive isolates, which should be further tested to rule out
Vibrio
species.

   
Turnaround time:
Cultures are incubated for 48 hours. Additional time is required for isolation and identification.

   Interpretation

   
Expected results:
No growth.

   Limitations

   
Vibrio
enteric infection may be missed if specific cultures are not requested.

WEST NILE VIRUS (WNV) SEROLOGY

   Definition

   WNV is a mosquito-transmitted Flavivirus of the family Flaviviridae. It is maintained in a cycle between birds and mosquitoes mostly belonging to the
Culex
genus. Besides horses and humans, several other mammals are deadend hosts of WNV. About 80% of humans infected with WNV develop no or only very mild symptoms. In about 20% of the cases, patients develop more severe symptoms such as fever, myalgia, and lymphadenopathy. Furthermore, in a small proportion of cases, the infection progresses to life-threatening neuroinvasive forms characterized by meningitis, encephalitis, and/or flaccid paralysis. The risk of developing lethal forms is increased in the elderly or in immunocompromised patients. WNV is most widely spread in temperate areas: isolated in parts of Europe, Middle East, Africa, Asia, America, and Australia. The IgM enzyme immunoassay (EIA) on CSF and/or serum is currently the most sensitive screening test for West Nile virus in humans.

   Use

   As an aid to the diagnosis of West Nile virus encephalitis.

   Interpretation