Standardization of Repeat Swab Cultures for Mycobacteria and Fungal Organisms

Beginning Thursday, September 19, 2013, the University of Iowa Hospitals and Clinics Microbiology laboratory will match the policy of the neighboring Iowa City Veteran’s Administration Hospital regarding repeat swab cultures for mycobacteria and fungi from a single site.  The following policy is the result of a joint effort between the Departments of Orthopedics, Infectious Disease and Pathology.

Because most repeat swab cultures are ordered on paper requisitions, rather than in Epic, providers may have to change how they typically obtain intraoperative cultures (e.g. by filling out multiple requisitions beforehand).  If multiple swabs are received from a single site, several considerations will apply:

  1. The laboratory will continue to accept any number of tissue or fluid samples from any number of sites for any type of culture. As a matter of laboratory utilization, please also do not add on mycobacterial and fungal cultures unless these pathogens are in the differential diagnosis for the patient.
  2. Swabs (ESwabs, PS #74541) are suboptimal for aerobic and anaerobic culture but will be accepted in multiple sets for these cultures if no other samples are available.
  3. If multiple swabs are sent to the laboratory from the same site, the preferred method of ordering will be to label one swab or order as having sampled the deepest and/or most involved site of potential infection. Only this swab will be used for mycobacterial and fungal culture.
  4. If no swab in a set is marked, the Microbiology laboratory will choose one for mycobacterial and fungal culture and cancel the remaining orders for these cultures. Aerobic and anaerobic cultures will be performed on the rest if also ordered. Review of ~1,400 swab cultures obtained in multiple sets revealed no positive cultures for any mycobacteria, yeast, or filamentous fungi, suggesting that this is a failsafe alternative. Overall, the hospital-wide yield of non-swab cultures for fungi is ~10%, illustrating the unsuitability of swabs for this purpose.

Questions concerning this broadcast can be directed to Bradley Ford, MD, PhD, Associate Medical Director of Microbiology, (ext. 6-2990,