The Resistant Pathogen Discussion Continues
Tuesday morning at ASM started with a symposium titled “Update on Gram-negative Pathogen Resistance and Lab Methods of Detection." To recap, David Landman from the State University of New York Downstate Medical Center in Brooklyn discussed resistance challenges with acinetobacter. Many strains have an outer cell membrane that is relatively impermeable to antibiotics, making it a highly resistant pathogen. Because of this, patients with acinetobacter infections face a high mortality rate. For more on acinetobacter, check out the current feature on the ADVANCE for Administrators of the Laboratory Web site.
Kenneth S. Thomson from Creighton University in Omaha discussed KPCs and carbapenemases and their association with false susceptibility. Thomson made an interesting note on reporting in vitro susceptibility for carbapenemase producers. Because of uncertainty in carbapenemase screens, laboratorians can report that a pathogen is resistant to carbapenemases, recommend an infectious disease consult, or call up a physician and comment on unproven clinical efficacy and explain that the results can't be fully interpreted. This, of course, requires an established relationship with the physician, a need that grows increasingly apparent as lab test results grow increasingly less cut-and-dry.
Nancy Hanson, PhD, also from Creighton University, discussed the need for molecular detection of hidden beta-lactamases. Assessing these beta-lactamases is essential for resistance detection, and Dr. Hanson notes that vigilant surveillance for infection control is more important now than ever before. Commercially available phenotypic tests for ESBLs, AmpCs and carbapenemases are imperfect due to variable susceptibility patterns. Thus, she states, microbiologists should demand commercially-available molecular tests for CTX-Ms, AmpCs and carbapenemases.