The Infectious Diseases Society of America (IDSA) and the American Society for Microbiology (ASM) released a new guide created to help infectious disease (ID) physicians decide what tests to request to diagnose infectious disease. The guide was published in the journal Clinical Infectious Diseases in July and relies heavily on a table format to aid ID physicians in picking the correct test for their patients.
The guide is divided into two sections. One covers anatomic systems, including infections of the bloodstream, cardiovascular system, central nervous system, eyes, soft tissue of the head and neck, upper and lower respiratory system, gastrointestinal tract, abdomen, bone and joints, urinary tract, genitals and skin and skin and soft tissues. The other section covers etiologic agent groups, like tickborne infections, viral syndromes, blood and tissue and parasite infections.
"It was created based on the need for it," said Ellen Jo Baron, PhD, who was a member of the author panel that completed the guide. Baron is also professor of pathology at Stanford University and Director of Medical Affairs, Cepheid, Sunnyvale, Calif. "Physicians don't really understand how to use the lab to help them with their patient information, and the microbiology field is changing really quickly. Plus, microbiology testing includes just about every kind of sample there is from the human body. There are different kinds of tests with different collection methods -- all kinds of factors that physicians may or may not know about."
"Medical knowledge and diagnostic capabilities are becoming ever more complex," added Peter H. Gilligan, PhD, another member of the guide's 18-member author panel. "This is an attempt to translate this complexity into a guide which is easy to understand and use."
The Tenets of Specimen Collection
Besides advising physicians on what test to request when they suspect a specific agent is causing the disease, the guide also provides details on the importance of proper specimen selection and collection for various cultures and tests.
The guide highlights 10 tenets of specimen management for all parties (physicians, nurses and laboratory technologists). They include:
- Specimens of poor quality must be rejected or results could be compromised.
- Physicians should not demand a report of "everything that grows" as this could result in an inaccurate diagnosis.
- Avoiding contamination of specimens is key, and careful collection is crucial.
- The laboratory requires a specimen, not a swab of a specimen, which may not hold enough infected material to ensure an accurate diagnosis and may be easily contaminated.
- The laboratory must follow its procedure manual or face legal challenges.
- A specimen should be collected prior to administration of antibiotics, presence of which could lead to misleading results.
- Susceptibility testing should be performed on clinically significant isolates, not all microorganisms in the culture.
- Lab results should be accurate, significant and clinically relevant.
- The laboratory -- not the medical staff -- should be allowed to set technical policy. Good communication and mutual respect will lead to collaborative policies.
- Specimens must be labeled accurately and completely (for example: dog bite wound, right forefinger).
An Important Document
This guide was created in hopes to be a useful tool for ID physicians to better understand what goes on with diagnosing a patient for an infectious disease.
"Every day, we meet with our ID colleagues to discuss how to make a lab diagnosis of an infectious disease. The initial stage of the process, selecting the specimen type to be analyzed, collecting it and getting it to the lab is essential to the success of this diagnostic endeavor," said Gilligan, who is also professor of pathology and laboratory medicine at the University of North Carolina Chapel Hill School of Medicine. "If selection, collection, and transport are not done properly, then diagnostic testing will not be optimal and has the potential to be misleading, resulting in either false positives or negatives. This document is the outgrowth of these types of discussions that occur daily in healthcare settings globally."
ASM has signed a memorandum of understanding with IDSA to make sure this guide will be a living document that is frequently updated, Dr. Gilligan added. "This is an exciting development, which hopefully will lead to many additional joint projects. This is an important strategic alliance for practicing clinical microbiologists with their key professional colleagues, ID physicians."
Amanda Koehler is a freelance writer.