Wounds (Deep) – Intraoperative / Interventional Abscess

by Jim Hutchinson

All intra-operative and interventional (usually collected in radiology) abscess cultures may yield bacteria or fungi. Both aerobic and anaerobic bacteria may be present. Samples may be from any body cavity or organ space. If the source is not clear consult with the charge technologist or microbiologist.

These samples are considered “precious” (can’t be recollected) and should be handled with priority.

Setup If thin fluid is received, centrifuge specimen at 3000 rpm for 10 minutes. If purulent or thick specimens are received, centrifugation is not required.

If parasitology is requested, separate a portion of the fresh specimen in one sterile container AND in a separate sterile container mix an equal volume of specimen with SAF. Label the specimen containers as “fresh specimen” and “specimen mixed with SAF” respectively.

Direct Examination

Gram stain

If fungus is requested, add:
Calcofluor stain

Culture

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
Wilkins Chalgren Agar (WC) AnO2, 35°C x 48 hours
WC Nalidixic acid – Tween 80 (NAT) AnO2, 35°C x 48 hours
WC Nalidixic acid – Vancomycin (NAV) AnO2, 35°C x 48 hours
Thioglycolate broth (THIO) O2, 35°C x 48 hours

If fungus is requested, add:

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

Interpretation If organisms were seen in direct Gram stain and cultures yield no corresponding growth after 48 hours of incubation, check direct Gram stain (if discrepant compared to original report, check with the Charge technologist), and re-incubate all plates an additional 48 hours and THIO a total of 7 days. If there is no evidence of corresponding growth after 7 days, subculture the THIO to CHOC and WC.

Examine the aerobic culture plates after 24 and 48 hours incubation and the anaerobic plates after 48 hours incubation. Examine the THIO daily for evidence of growth. If no growth on culture plates but evidence of growth in THIO, then perform Gram stain and subculture THIO onto BA, MAC, CHOC and WC (plus additional media as appropriate) and incubate and process as above.

All isolates should be identified.

Reporting

Gram stain

Report with quantitation the presence of pus cells and organisms.

Culture

Negative Report
“No growth”
Positive Report
Report all isolates with appropriate sensitivities.

Telephone results of positive Gram stain and isolates to the ward / ordering physician.

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.

H.D. Isenberg. 2004. Microbiological Assessment of Orthopedic Surgery Sites p. 13.14.1 – 13.14.6 In Clinical Microbiology Procedures Handbook, 2nd Edition, Vol 1 ASM Press, Washington, D.C

Cumitech 23 Infections of the Skin and Subcutaneous Tissues June 1988

H.D. Isenberg. 2004. Culture for anaerobes p. 4.3.1 – 4.3.9 In Clinical Microbiology Procedures Handbook, 2nd Edition, Vol 1 ASM Press, Washington, D.C.

H.D. Isenberg. 2004. Examination of Primary Culture plates for anaerobic bacteria. p. 4.4.1 – 4.4.6 In Clinical Microbiology Procedures Handbook, 2nd Edition, Vol 1 ASM Press, Washington, D.C.

H.D. Isenberg. 2004. Incubation techniques for anaerobic bacteriology specimens. p. 4.5.1 – 4.5.4 In Clinical Microbiology Procedures Handbook, 2nd Edition, Vol 1 ASM Press, Washington, D.C.

Cumitech 5A Practical anaerobic bacteriology December 1991.