Bone marrow

Infection of bone marrow is uncommon. However, it may be a site of infection with bacteria or fungi or tuberculosis in patients with disseminated disease.

Setup If <1 ml is received, sterile saline may be added to a final volume of 1 ml so that the media listed below can be inoculated.

If a clotted specimen is received, emulsify the coagulated material using a sterile swab or loop.

A portion of ALL specimens should be forwarded for Mycobacteria (TB) culture.

Direct Examination

Gram stain KOH Calcofluor white stain


Media Incubation
Blood Agar (BA) CO2, 35°C x 48 hours
Chocolate Agar (CHOC) CO2, 35°C x 48 hours
Wilkins Chalgren Agar (WC) AnO2, 35°C x 48 hours
Sabouraud’s Heart Infusion Agar (SABHI) O2, 30°C x 4 weeks
SABHI with Chloramphenicol (SABHI-C) O2, 30°C x 4 weeks
Thioglycolate broth (THIO) O2, 35°C x 48 hours

Interpretation Examine the BA, CHOC plates and THIO at 24 and 48 hours and the WC plate after 48 hours incubation. If no growth on the culture plates but evidence of growth in THIO, perform Gram stain and sub-culture the THIO onto BA, CHOC and other media as appropriate.

If bone marrow received in blood culture bottle(s), process as a routine blood culture. Do NOT inoculate blood culture bottle(s) in the lab.

All isolates are to be identified.


Gram stain

Report the presence or absence of organisms.


Negative Report “No growth”

Positive Report Report all isolates with appropriate susceptibilities. Do not quantitate except if it is from the fluid medium only – add comment “From broth culture only, indicative of small numbers and/or contamination.”

Call all positive Gram stains and cultures to ward/ordering physician.

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. Blood Cultures-General Detection and Interpretation, p. In Clinical Microbiology Procedures Handbook, 2nd ed. Vol.1 ASM Press, Washington, D.C.