Table 1.

Comparison of laboratory methods for direct detection of infections

Technique	Sensitivity	Turnaround	Availability
Culture	Moderate	> 3 days	-Expensive -Virus culture expertise disappearing, now little use in clinical laboratories for primary diagnosis -Reference activity for antigenic monitoring, e.g. for influenza
Electron microscopy	Low	<1 day	-Expensive -Expertise disappearing, little used clinically -Reference tests for ‘new’ infections
Antigen detection	Moderate	< 1 day	-Laboratory-based tests for HIV, rotavirus available -Wider use of point-of-care tests within clinics likely -Use in clinical setting requires quality control
Direct immunofluorescence	Moderate	<1 day	-Moderate cost -Still in use for respiratory infections
Polymerase chain reaction	High	<1 day	-Highly sensitive and specific, moderate cost -Most widely used approach in clinical setting -Used for quantification to guide treatment and to monitor progress -Combined with sequencing to define antiviral sensitivity and for genotyping