REPORTING

Organism identification

Should common or scientific names be used when reporting the presence of parasites?

The scientific name (genus, species) names should be used on the final report that goes to the physician and to the patient’s chart.  It is also recommended that the stage of the organism be included (trophozoite, cyst, oocyst, spore, egg, larvae, adult worm - various stages of the malaria parasites/will impact therapy).

What happens if there are several different names used in the literature (Giardia lamblia, G. intestinalis, G. duodenalis)?

It is appropriate to use the most commonly accepted name (Giardia lamblia); you can also let the proficiency testing organism lists be your guide.  When a replacement name begins to appear on the proficiency test list, then it’s appropriate to notify your clients and institute the name change.  Remember, it is very important to notify all clients prior to making any name changes.

How has the reporting of Cryptosporidium parvum changed and why?

It is now known that more than one species of Cryptosporidium can cause disease in humans (C. parvum: humans and other mammals; C. hominis: humans).  However, the different species cannot be differentiated on the basis of morphology.  It is now recommended that the more correct reporting format would be:  Cryptosporidium spp. (rather than Cryptosporidium parvum).

Should WBCs and/or other cells or yeast be reported and why?

The reporting and quantitation (rare, few, moderate, many) of WBCs (PMNs, macrophages, eosinophils) provides some additional information for the physician.  If the patient continues to have diarrhea, it may give the physician something more to consider, particularly if stool culture has not been ordered.  Also, conditions related to non-infectious diarrheas may also result in WBCs and macrophages in the stool.  We always include this type of information/explanation in our educational process regarding reporting formats.  Physicians can then decide on the relevance of the information.  Remember, that when reporting WBCs, we can also identify eosinophils (may or may not be related to parasitic infection and may or may not correlate with peripheral eosinophilia – this information may also be helpful.

Yeast is a bit different.  In order to report anything about yeast, you must know the stool was fresh or immediately put in preservative.  If there are lots of yeast, budding yeast and/or pseudophyphae, then this provides some additional information for the physician, often depending on the patient's general condition and whether or not they are immunosuppressed.  However, if you don't know whether the collection criteria were met, then reporting anything about yeast is NOT recommended.

How should Blastocystis hominis be reported?

In the past there was some agreement that the number of organisms present (mod, many, packed) were more likely to be associated with symptoms.  However, in the past few years, there have been anecdotal reports of patients being symptomatic with rare or few organisms, as well.  The current recommendation is to report the organism and quantitate per rare, few, mod, many, packed (using your proficiency testing quantitation scheme).  It is important to confirm the physicians know what the report means and understand the controversial issues surrounding this organism - they can then correlate the numbers with symptoms.  If rare or few, there is no solid data per numbers relevance other than the anecdotal case reports (many of which are word of mouth).  Per the pathogenicity issue, there's still a lot of controversy.  However, many physicians are treating if the patient is symptomatic and no other organisms are found (including coccidia and/or microsporidia).

Blastocystis hominis may actually be a mix of several strains, some of which are pathogenic and some nonpathogenic.  Based on continuing molecular studies, changes in the classification of this group could change soon.  If both types of strains currently make up what is called “Blastocystis hominis” – this could explain the controversy regarding pathogenicity and the fact that some patients are symptomatic, while some are asymptomatic.

How should intestinal protozoa be reported?

Reporting trophs/cysts:  This has been the accepted way of reporting intestinal protozoa for a couple of reasons:  Different drugs are used to treat Entamoeba histolytica cysts vs. trophs.  Also, since the cyst form is the infective stage for the protozoa (exception:  D. fragilis and the
trichomonads), the report does convey some epidemiologic information.  For these reasons, the current recommendation is to continue to report all protozoa (genus, species, stage).

What additional reporting comments should be added to the reporting of the O&P examination and the fecal immunoassays?

It is important to add the following comment to the O&P examination:
“The O&P examination is not designed to detect the intestinal coccidia (Cryptosporidium spp., Cyclospora cayetanensis) or the microsporidia.  Isospora belli oocysts (coccidia) can be detected from the concentration sediment examination.”

Report the results of the fecal immunoassays based on the specific organism(s) relevant to the kit:
“No Giardia lamblia antigen detected.”  OR “Giardia lamblia antigen present.”
“No Giardia lamblia or Cryptosporidium spp. antigen detected.”
OR
“Negative for Giardia lambli.”
“Negative for Giardia lamblia and Cryptosporidium spp.”

Quantitation

What organisms should be quantitated in the final report to the physician and patient’s chart?

Organisms and non-organism cells/structures (stool blood cells, Charcot-Leyden crystals) that are recommended for quantitation include the following:
A. Intestinal protozoa:  Blastocystis hominis
B. Helminths:  Trichuris trichiura eggs, Clonorchis sinensis eggs, schistosome eggs (also report viability).
C. Blood parasites:  all malaria organisms
D. Blood cells (PMNs, macrophages, RBCs)
E. Charcot-Leyden (CL) crystals

Why are all proficiency testing specimen answers reported and quantitated, while clinical specimen reports are rarely quantitated in terms of organism numbers?

There are two issues to consider.
(1) When reporting proficiency testing (PT) specimen results, you are asked to quantitate organisms in both the formalin wet mounts and permanent stained smears.  This information serves as a quality control check for the proficiency testing agency to ensure that organism numbers are consistent throughout the challenge vials/slides.

(2) Most laboratories (with few organism exceptions) do not quantitate organisms on the concentration or permanent stained smear reports.  Some exceptions might be:  Trichuris trichiura eggs in a concentration wet mount (light infections might not be treated).  Since many organisms are shed on a random basis, quantitation may change dramatically from day to day and generally has little clinical relevance.