Commonly Performed Serologic Tests for Diagnosis of Recent Bacterial Infections
| Organism | Test | Clinically Significant Result* |
|---|---|---|
| Staphylococcus aureus | Immunodiffusion for teichoic acid antibodies |  1:4 |
| Streptococcus pyogenes | Antistreptolysin O (ASO) | 1:240 |
| Anti-DNAase B | 1:240 | |
| Antihyaluronidase | 4× titer rise | |
| Salmonella typhi (typhoid fever) | Widal test | 4× titer rise |
| Legionella pneumophila (Legionnaires' disease) | Indirect immunofluorescence | 1:256 |
| Treponema pallidum | Rapid plasma reagin (RPR) | 1:8 |
| Venereal Disease Research Laboratory (VDRL) | 1:8 | |
| Fluorescent treponemal antibody-absorption (FTA-ABS) (IgM) | Positive | |
| Borrelia burgdorferi (Lyme disease) | Indirect immunofluorescence | 1:128 |
| Mycoplasma pneumoniae (atypical pneumonia) | Cold agglutinins | 1:128 |
| Mycoplasma pneumoniae (atypical pneumonia) | Complement fixation | 1:32 |
| Rickettsia rickettsii (spotted and typhus fevers) | Weil-Felix (OX-19) | 1:320 |
* Titers greater than or equal to those displayed in the table or fourfold or greater rises in titer between acute and convalescent sera are only suggestive of recent infection by all of the agents listed. Titers less than those displayed in the table do not rule out infection.
Adapted from Sacher, RA, and McPherson, RA: Widmann's Clinical Interpretation of Laboratory Tests, ed 11. FA Davis, Philadelphia 2000, p 709.