Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1334 page)

   CSF should be transported at room temperature; do not refrigerate or freeze for transport.

   Specimens submitted for bacterial culture are also acceptable for fungal or mycobacterial stains and culture, antigen testing, and VDRL, if sufficient volume of fluid is submitted.

   Interpretation

   
Expected results:
No growth. False-negative cultures may be caused by low pathogen concentration in CSF, especially when low-volume samples are submitted, or prior antibiotic therapy.

   
Positive results:
Positive CSF culture supports a specific diagnosis of meningitis. False-positive cultures may be caused by contamination with endogenous skin flora. For most bacterial pathogens, CSF samples in patients with acute bacterial meningitis usually show increased WBCs (PMNs predominate), increased protein, and decreased glucose.

   Limitations

   A broad etiology, which may require a number of different tests for diagnosis, may be considered for patients presenting with signs and symptoms of meningitis. The volume of CSF submitted is often insufficient for optimal sensitivity for the range of tests requested.

CHLAMYDIA TRACHOMATIS
, AMPLIFIED NUCLEIC ACID DETECTION

See: Sexually Transmitted Infections, Molecular Diagnosis (
Chlamydia trachomatis
,
Neisseria gonorrhoeae
,
Trichomonas vaginalis
)

CHLAMYDIA TRACHOMATIS
CULTURE

   Use

   
C
.
trachomatis
is an obligate intracellular pathogen, and this culture may be used to diagnose
C
.
trachomatis
infections. Although tests based on nucleic acid amplification have emerged as the most sensitive methods for diagnosis of
Chlamydia
genital infections,
Chlamydia
culture is still required for specimen types for which molecular diagnostic tests have not been validated.
Chlamydia
cultures should also be performed in cases that may have legal implications, such as rape and child abuse.

   Method:

   Infected cells from patient specimens are inoculated onto cultured eukaryotic cells, most commonly McCoy cells.

   Cultures are incubated for 48–72 hours.