Screening of auramine-stained smears of all fecal samples is a rapid and inexpensive way to increase the detection of coccidial infections.
BACKGROUND
Coccidia are important causes of diarrhea that is often indistinguishable from other forms of community-acquired diarrhea. However, the detection of oocysts is often only performed when explicitly requested, as part of the ova and parasite (O&P) examination. Reappraisal and understanding of the accurate staining characteristics of auramine O (AuO), which stains nucleic acids, may permit the inexpensive and reliable identification of coccidian oocysts at routine workup of all fecal samples.


METHODS
AuO-stained smears were prepared from all stool samples received for stool culture in transport medium (SC) and from concentrated stools received for the ova and parasite (O&P) examination.


RESULTS
A total of 3732 samples for stool cultures and 3132 samples for O&P examinations were included. Ninety-one samples (1.3%) from 52 patients yielded Coccidia (45 Cryptosporidium spp and 7 Isospora belli). In seven cases oocysts were only detected in samples sent for stool culture in transport medium. The oocysts showed a typical staining pattern and were easy to recognize. The observation of one smear took only around 30seconds, and the reagents and glass slide for one smear did not exceed US$ 0.03.


CONCLUSIONS
The screening of all fecal samples with AuO-stained smears is a rapid and inexpensive way to increase the detection of coccidial infections, which in most laboratories can be incorporated into the microscopic workup for mycobacteria.
Hanscheid
T
T
Unidade de Microbiologia Molecular e Infecção, Instituto de Medicina Molecular, Faculdade de Medicina, Hospital Universitário de Santa Maria, Av. Prof. Egas Moniz, P-1649-028 Lisbon, Portugal. t.hanscheid@fm.ul.pt
Cristino
J Melo
JM
Salgado
M J
MJ
D000328:Adult; D000818:Animals; D001576:Benzophenoneidum; D002648:Child; D003048:Coccidiosis / Q000175:diagnosis*; D005243:Feces / Q000469:parasitology*; D006801:Humans; D008828:Microbiological Techniques / Q000191:economics / Q000379:methods*; D033661:Oocysts / Q000469:parasitology; D012680:Sensitivity and Specificity
D001576:Benzophenoneidum