Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1387 page)

   HPV molecular testing is performed as a reflex test for women older than 21 with atypical cells of undetermined significance (ASC-US) Pap test result,

   HPV molecular testing is performed concurrently with a Pap test for women 30 years and older.

   Limitations

   Test results may be affected by improper specimen collection, storage, or specimen processing.

   Cervista
^™
HPV HR HPV tests, Cobas HPV Test, and TIGRIS DTS detect high-risk HPV types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66 (with exception of Hybrid Capture 2 HR HPV), and 68 but not HPV low-risk types.

   Testing of alternate specimen types (rectal and oropharyngeal) is not currently FDA approved; however, some laboratories have conducted validation studies to offer testing.

LEGIONELLA ANTIGEN SCREEN

   Definition

   Legionellosis refers to two clinical syndromes caused by bacteria of the genus
Legionella
—Legionnaires disease and Pontiac fever. Legionnaires disease is considered an atypical pneumonia.
Legionella pneumophila
is responsible for approximately 90% of infections. Most cases are caused by
L
.
pneumophila
, serogroup 1. Although a number of prominent clinical manifestations are distinctive for
Legionella
infection, none of them are pathognomonic or highly specific. Therefore, laboratory testing using specialized tests for
Legionella
should be considered for all patients hospitalized with community-acquired pneumonia.

   Culturing for
Legionella
species is the single most important laboratory test. Urinary antigen testing is rapid, sensitive, and specific, but it is only useful for the diagnosis of
L
.
pneumophila
type 1 infection. The combination of culture of an appropriate respiratory specimen and urinary antigen testing is optimal as a diagnostic approach. Serologic tests are generally far less useful for the diagnosis of an individual patient. Although PCR-based tests exist, to date they do not exceed the sensitivity of culturing the organism.

   
Normal range:
Negative.

   Use

   In conjunction to culture for the presumptive diagnosis of past or current Legionnaire disease (
L
.
pneumophila
serogroup 1), patients suspected of health care–associated pneumonia, patients who have failed outpatient antibiotic therapy, and patients with a travel history within 2 weeks before the onset of illness.