Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1390 page)

   Limitations

   
Legionella
are typically present in low concentrations in patient specimens. Isolation of
Legionella
from infected extrapulmonary specimens is inconsistent.

   Diagnosis of legionellosis may require multiple testing modalities, including culture, serology, PCR, and antigen detection methods, in conjunction with clinical findings.

   
Common pitfalls:

   The rejection criteria applied to sputum specimens for routine bacterial cultures should not be applied to specimens submitted for
Legionella
culture.

   
Legionella
may be present in very low concentrations in respiratory secretions. Therefore, BAL and bronchial brush specimens should be directly inoculated onto BCYE media before dilutions are prepared for quantitative bacterial cultures.

MACROSCOPIC EXAMINATION, ARTHROPOD

   Use

   This test is used to identify arthropods by visual examination. This test is indicated for identification of ticks, mites, fleas, spiders, lice, maggots, and other insects that may be associated with human infection, infestation, disease, or disease transmission.

   
Method

   These agents are submitted in clean containers with tight-fitting lids. Specimens for scabies detection may be collected by skin scraping.

   Plucked hair may be submitted for identification of nits and the eggs of lice. Maggots may be expelled spontaneously, surgically, by vacuum extraction, or by other methods.

   The submitted arthropods and insects are inspected by the naked eye or with low-power microscopy. Identification is based on morphologic features.

   
Turnaround time:
24–48 hours.