TABLE 6.

Comparison of assays available for diagnosis of ocular C. trachomatis infection

Test	Detection target	Specimens	Check for specimen adequacy?	Transport conditions	Technical complexity	Processing time	Performance characteristicsa		Cost
							Sensitivity (%)	Specificity (%)
Microscopy
Giemsa/iodine	Inclusions	Conjunctival scraping	Yes	No refrigeration required	++	30 min	30-60	50-70	+
Fluorescein	Antigen	Conjunctival swab			++	30 min	60-80	80-95	++
Culture	Infectious organisms	Conjunctival swab	No	Cold chain in transport medium	+++	48-72 h	50-70	100	++++
Enzyme immunoassay
Lab based	Antigen	Conjunctival swab	No	No refrigeration required	++	4-6 h	60-80	80-95	+
Rapid					+	30 min	50-70	80-95	++
Nucleic acid hybridization	DNA	Conjunctival swab	No	No refrigeration requiredb	++++	4-6 h	60-80	95-100	+++
Nucleic acid amplification	DNA or RNA	Conjunctival swab	No	No refrigeration requiredb	++++	4-6 h	90-100	95-100	++++
						1-2 h for     real-time     PCR
Serology	Human antichlamydial antibody (IgA, IgG, or IgM)	Serum, tears	Yes	No refrigeration required	+++	4-6 h	?	?	+++

^aPerformance compared against a reference standard of culture and/or nucleic acid amplification test. The ranges given represent best current estimates; the difficulties involved in assigning numerical values to the sensitivity and specificity of diagnostic tests for ocular C. trachomatis are discussed in the text.

^bRequirements for transport medium and transport conditions vary for different assays.