Table III-1.
Laboratory Diagnosis of Periocular Structure Infections/Conjunctivitis, Orbital and Periorbital Cellulitis, Lacrimal and Eyelid Infections
| Etiologic Agents | Diagnostic Procedures | Optimum Specimens | Transport Issues; Optimal Transport Time |
|---|---|---|---|
| Bacteria | |||
| Haemophilus influenzae | Gram stain | Conjunctival swab | Swab transport device, RT, 2 h |
| Streptococcus pneumoniae | Aerobic bacterial culture | ||
| Staphylococcus aureus | |||
| Moraxella catarrhalis and other species | |||
| Streptococcus pyogenes | |||
| Escherichia coli | |||
| Other Enterobacteriaceae | |||
| Neisseria gonorrhoeae | |||
| Actinomyces spp | Anaerobic bacterial culture | Conjunctival scraping or biopsy | Sterile anaerobic container, RT, immediately |
| Other anaerobic bacteria (rare cause of canaliculitis) | |||
| Chlamydia trachomatis | Direct fluorescent antibody stain | Conjunctival swab | Virus swab transport device, RT, 2 h |
| Chlamydia cell culture | |||
| NAATa,b | |||
| Viruses | |||
| Herpes simplex virus (HSV) | HSV NAAT | Conjunctival swab | Virus swab transport device, RT, 2 h |
| HSV culture | |||
| Varicella zoster virus (VZV) | VZV NAAT | Conjunctival swab | Virus swab transport device, RT, 2 h |
| VZV culture | |||
| Adenovirus | Adenovirus NAAT | Conjunctival swab | Virus swab transport device, RT, 2 h |
| Adenovirus culture | |||
| Herpes B virus | c | ||
Abbreviations: NAAT, nucleic acid amplification test; RT, room temperature
a NAATs for detection of C. trachomatis have not yet been approved in the United States for use with conjunctival swab specimens. Individual laboratories, however, may have validated NAATs for examination of specimens obtained from patients with conjunctivitis and studies suggest that NAATs are more sensitive than cultures.
b Use of NAAT for detection of C. trachomatisis is considered an “off label” use of this test. Laboratories that offer such testing must conduct in house validation of these assays before offering NAAT as a diagnostic test.
c Culturing of specimens thought to harbor Herpes B virus (primate origin) requires use of biosafety level 4 precautions in the laboratory and testing is almost always referred to a specialized reference laboratory. Consult the laboratory when Herpes B virus is suspected.