Bronchoalveolar Lavage (BAL), Bronchoscopy Aspirates / Washings

Bronchoalveolar lavage (BAL) specimens, including aspirates and washings are collected when sputum specimens fail to identify an etiologic agent of pneumonia or the patient is unable to produce sputum. Lavages are especially suitable for detecting Pneumocystis carinii (jiroveci) and fungi.



Centrifuge the specimen (3000 rpm x 10 minutes). Transfer the supernatant into a sterile container and refrigerate until the final report is issued. Label the container as supernatant. Use the sediment to prepare the smears and inoculate the culture media.

Direct Examination

Prepare 3 smears for:

  • Gram stain
  • KOH Calcofluor stain – to be read only if specifically requested.
  • Auramine stain – to be read only if specifically requested.


Blood Agar (BA) CO2 35°C x 48 hours
MacConkey Agar (MAC) O2 35°C x 48 hours
Chocolate Agar (CHOC) CO2 35°C x 48 hours
Sabouraud Brain Heart Infusion Agar (SABHI) O2 30°C x 4 weeks
SABHI with Chloramphenicol (SABHI-C) O2 30°C x 4 weeks

If B. cepacia is requested or specimen is from a patient with Cystic Fibrosis, add:

*Burkholderia cepacia* Agar (BC) O2 35°C x 3 days

Keep the BA, CHOC and MAC plates CO2 35°C x 3 days

If Nocardia is requested, add:

Vancomycin Colistin Nalidixic acid (VCN) CO2 35°C x 5 days

Interpretation Examine the plates after 24 and 48 hours incubation.

Identify any growth of Probable respiratory pathogens.

Identify any growth of Possible respiratory pathogens if predominant (i.e. amount of pathogen growth greater than that of normal oral flora).

If there is a question regarding the significance of an isolate, consult the lead technologist or microbiologist.

Probable respiratory pathogens (to be worked up in any amount)

  • Streptococcus pneumoniae
  • Moraxella catarrhalis
  • Hemophilus influenzae
  • Group A streptococcus
  • Pseudomonas spp.
  • Non-fermenting Gram negative bacilli
  • Burkholderia cepacia
  • Nocardia spp.
  • Filamentous fungus
  • Cryptococcus neoformans

Possible respiratory pathogens (to be worked up when predominant)

  • Staphylococcus aureus
  • Enterobacteriaciae

These organisms are commonly found in lower respiratory specimens in small amounts in association with normal oral flora. Report only normal oral flora in this circumstance.

  • Yeast not Cryptococcus neoformans
  • Group B, C and G streptococcus
  • Other gram negative bacilli (not listed above) of single morphological type


Direct Examination

Gram Stain

  • WBCs
  • epithelial cells
  • predominant respiratory pathogens
  • “Normal oral flora”
  • “No bacteria seen” if no organism is seen.

If yeast is predominant organism seen report with quantitation. If yeast is not the predominant organism, report the Gram stain as usual and do not identify the presence of yeast.

KOH Calcofluor Stain
Report fungal elements seen or not seen.

Acid-fast stain (if STAT request)
Report AFB seen or not seen.


“Normal oral flora” (DO NOT quantitate) or “No growth”
“No B. cepacia isolated” if B. cepacia culture is requested.
“No Nocardia isolated” if Nocardia culture is requested.

Report all significant isolates with appropriate susceptibilities.
Report “Normal oral flora” if also present.
Report “Filamentous fungus isolated identification to follow” if present (Do not quantitate).

References P.R. Murray, E.J. Baron, M.A. Pfaller, R.H. Yolken. 2003. Manual of Clinical Microbiology, 8th ed. ASM Press, Washington, D.C.

H.D. Izenberg. 2003. Respiratory Tract Cultures, – in Clinical Microbiology Procedures Handbook, 2nd ed. Vol.1 ASM Press, Washington, D.C