Autopsy

Specimens collected at autopsy are often contaminated with faecal or skin flora making the interpretation of cultures very difficult. The finding of a specific organism may be very noteworthy, however.

Setup

Direct Examination

Prepare 2 touch preparations using a freshly cut surface of representative material. Gram stain one and retain the other for potential future stains.

Culture

Macerate the tissue using a grinder. Bone should be inoculated into Thioglycolate broth and not macerated.

Media Incubation
Blood Agar (BA) CO2, 35°C x 48 hours
Chocolate Agar (CHOC) CO2, 35°C x 48 hours
MacConkey Agar (MAC) O2, 35°C x 48 hours
Phenyl Ethyl Alcohol Agar (PEA) O2, 35°C x 48 hours

For all lung specimens or if fungal culture specifically requested:

Sabouraud’s Heart Infusion Agar (SABHI) O2, 30°C x 4 weeks
SABHI with Chloramphenicol (SABHI-C) O2, 30°C x 4 weeks

Followup Examine plates after 24 and 48 hours incubation and identify any pure growth of any potential pathogen. Mixed cultures should not be worked up. Consult with charge technologist or microbiologist if in doubt.

Reporting

Gram stain

Report with quantitation the presence of pus cells and organisms.

Culture

Negative Report “No growth” or “Mixed flora suggesting contamination”

Positive Report Report all significant isolates WITHOUT susceptibilities.

References H.D. Isenberg. 2004. Specimen Collection, Transport and Acceptability p. 2.1.1 – 2.1.28. In Clinical Microbiology Procedures handbook, 2nd Edition, Vol 1 ASM Press, Washington, D.C

H.D. Isenberg, 2004. Wound Cultures – Wound and Soft Tissue Cultures, p. 3.13.1.1 – 3.13.1.16. In Clinical Microbiology Procedures Handbook, 2nd Edition, Vol 1 ASM Press, Washington, D.C.