Changes to Bacterial Identification in the Clinical Microbiology Laboratory

As of yesterday, January 6, 2014, the University of Iowa Hospitals and Clinics Microbiology laboratory began identifying most types of routinely-encountered bacteria by matrix assisted laser desorption time of flight mass spectrometry (MALDI-TOF MS).

While this is primarily an internal laboratory conversion, it has several significant benefits to clinical care:

  1. Most identifications will be made more quickly.  However, susceptibility testing will not be done more rapidly and an increased time gap between identification and receipt of susceptibility testing may be perceived in some cases.  Please call the Microbiology resident on call at pager 5582 or the Associate Medical Director at the number below with questions, or consult the antibiogram for guidance:
  2. Some species formerly reported as groups will be split into individual species in some but not all cases. This will occur most commonly with Enterococcus spp., species of coagulase-negative Staphylococci, and Corynebacterium spp. (formerly and usually reported as “diptheroids” but extremely variable in their species-to-species antimicrobial susceptibility profiles).
  3. A comment will be appended to bacterial identifications regarding the FDA status of the method of identification.  This is a regulatory requirement.  This method was extensively validated by our in-house study.

Please contact the Microbiology resident on call at pager 5582 or the number below with consultative and interpretive questions arising as a consequence of this change.

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