Method of Obtaining Specimen
The options are as follows:
- Sputum Gram Stain:
May occasionally be helpful if there is a large number of white blood cells and bacteria
consistent with oropharyngeal flora.
- Bronchoscopy:
- Triple lumen catheter: Routine aspirates during bronchoscopy is useless for
anaerobic cultures. The bronchoscope passes through oropharynx and will be contaminated by
the oropharyngeal flora. You need to use triple lumen catheter to avoid contamination and
obtain material selectively from the involved segment.
- Bronchial lavage: The second option is to obtain a bronchial lavage from the
involved segment and perform quantitative bacterial cultures.
- Fine Needle Aspiration:
In the pre-antibiotic era needle aspirations of lung abscess were fraught with fear of
development of bronchopleural fistula and empyema. With the current option of FNAB under
CT guidance, it is being done with increasing frequency and safety. Uncontaminated
aspirate can be obtained by this method for cultures. This procedure is often the method
of choice for obtaining the specimen in children as other options are not easily feasible
in this population.
- No Need for Cultures:
When the patient has foul smelling sputum the anaerobic infection is obvious and there may
not be a need for confirmation, as many of these procedures are expensive and attendant
with some risks. Most of the lung abscess respond to empiric therapy. The primary purpose
for culture is to obtain antibiotic sensitivity and can be reserved to cases not
responding to empiric therapy.