Department of Pediatrics
Division of Gastroenterology, Hepatology, Nutrition
We have read the exceptionally comprehensive IDSA/ASM Guidelines on laboratory diagnosis (Clin
Infect Dis. 2013 Aug;57(4):485-8). The microbiology laboratory-provider interface is an area of effort
that is under-appreciated in patient care systems, and your outstanding work will help bridge that gap.
However, as individuals who care for many children with bacterial enteric infections, and as
investigators in the field of gastrointestinal illnesses, we are very concerned about the recommendation
for stool specimen submission. Briefly, we strongly believe that the acutely ill patient with diarrhea who
warrants testing for a bacterial enteric infection should undergo such evaluation as a matter of priority.
We also believe that a policy that encourages specimens submitted in cups hinders that process.
Here are our thoughts:
1. Cup specimens are notoriously difficult to obtain, even among the presumably motivated group of
patients who visit emergency facilities. Figure 1 in
http://cid.oxfordjournals.org/content/43/7/807.long demonstrates just how difficult it is to obtain
stool specimens in cups, if left to patient/parent preference.
2. There are important specimen custody issues: If a patient can’t produce specimen on site, it is very
cumbersome to return it to a facility for culture. Questions that arise include: where in the institution
should it go? Is the doctor’s office open? Are there drop off issues? Did it really come from the patient?
Will the right paperwork accompany the specimen?
Also, if a patient is admitted from an emergency facility, there are frequent hand-off glitches, and it is
often unclear if a test is truly pending, or has merely been ordered. There is no value in delaying taking
possession of a specimen that could contain a bacterial pathogen, and considerable value in accelerating
the time to result (even if negative).
3. It is difficult to state with certainty, but biohazard control might be easier to implement using a
contained swab culture system than a patient – managed cup specimen. Specifically, the sheathed swab
system seems more hygienic.
4. The “rectum to plate” interval is shorter using a swab-based protocol than a cup from home to an
institution or office to a laboratory pathway. A few hours gained by sending a swab on presentation
could result in a day earlier time to result.
5. If a patient with diarrhea presents to an ER, the organisms that are traditionally the most important
to find (i.e., bacterial enteric pathogens) are not those best diagnosed in cup specimens (though we do
acknowledge access issues play a role in choice of place of presentation of less than acute illnesses to
acute care facilities).
6. The references cited in the Guidelines as supporting the superiority of cup stool specimens do not
demonstrate the inferiority of swab cultures. Reference 106 (Diagn Microbiol Infect Dis 2006;56:123-6)
pertains only to Salmonella, and, in fact, finds merit in testing both cups and swabs. Reference 107 (J Clin
Microbiol 2007;45:1278-83) reports that bulk stool and swabs have equivalent yields for bacterial enteric
pathogens.
Phillip I. Tarr, M.D.
Melvin E. Carnahan Professor of Pediatrics
Professor of Molecular Microbiology
Director, Division of Pediatric Gastroenterology, Hepatology and Nutrition
Co-Leader, Pathobiology Research Unit, Washington University School of Medicine
Lori Holtz, M.D.
Assistant Professor of Pediatrics, Division of Gastroenterology, Hepatology & Nutrition
Washington University School of Medicine
Ryan McKee, M.D.
Clinical Fellow, Division of Pediatrics Emergency Medicine
Washington University School of Medicine
David Schnadower, M.D., M.P.H.
Fellowship Director, Division of Pediatric Emergency Medicine
Washington University School of Medicine
Rebecca Stolle, R.N.
St. Louis Children’s Hospital
Donna M. Denno, M.D., M.P.H.
Associate Professor of Pediatrics
Adjunct Associate Professor, Health Services Departments of Pediatrics and Global Health
University of Washington
Eileen J. Klein, MD, MPH
Professor, Pediatrics
Fellowship Director, Pediatric Emergency Medicine
Co-Director, Emergency Department Research
University of Washington and Seattle Children's Hospital
Stephen B. Freedman, .M.D.C.M., M.S.c.
Associate Professor of Pediatrics
Sections of Pediatric Emergency Medicine and Gastroenterology
Alberta Children's Hospital and University of Calgary