Chilomastix mesnili
المؤلف:
Patricia M. Tille, PhD, MLS(ASCP)
المصدر:
Bailey & Scotts Diagnostic Microbiology
الجزء والصفحة:
13th Edition , p608
2025-09-30
243
General Characteristics
C. mesnili has both trophozoite and cyst stages and is somewhat more easily identified than are some of the smaller flagellates, such as E. hominis and R. intestinalis (see Tables 1 and 2; see Figure 1). The C. mesnili trophozoite is pear shaped, measuring 6 to 24 µm long and 4 to 8 µm wide. It has a single nucleus and a distinct oral groove, or cytostome (mouth), close to the nucleus. Flagella are difficult to see without obvious motility in a wet preparation. The morphology can be seen on the permanent stained smear; the cytostome may be visible in some trophozoites. The cysts are pear or lemon shaped and range from 6 to 10 µm long and 4 to 6 µm wide (see Figure 2). They have a single nucleus and a typical curved cytostomal fibril, called the shepherd’s crook. The cyst’s definitive morphology can be seen on a permanent stain.
Table1. Intestinal Protozoa—Trophozoites of Flagellates.
Table2. Intestinal Protozoa—Cysts of Flagellates
Fig1. A to C, Trophozoites of Chilomastix mesnili (A, silver stain). D and E, Cysts of C. mesnili.
Fig1. A, Chilomastix mesnili trophozoite. B, Chilomastix mesnili cyst (both top figures are iodine stain). C, Chilomastix mesnili trophozoite (silver stain). D, C. mesnili cyst. (A and B courtesy Dr. Henry Travers, Sioux Falls, S.D.)
Epidemiology
C. mesnili tends to have a cosmopolitan distribution, although it is found more frequently in warm climates. Transmission occurs through ingestion of infective cysts.
Pathogeneis and Spectrum of Disease
C. mesnili is considered nonpathogenic and does not cause disease.
Laboratory Diagnosis
Although cysts sometimes can be seen in a wet preparation, definitive identification of C. mesnili relies on examination of permanent stained smears.
Therapy
Specific treatment is not recommended for C. mesnili. Because these nonpathogenic organisms are acquired through fecal-oral contamination, both pathogens and nonpathogens can be found in the same patient. If few organisms are present, extended microscopic examination and multiple organism measurements are required for definitive identification. It is always important to report pathogens and nonpathogens, because they are acquired the same way.
Prevention
Prevention depends on adequate disposal of human excreta and improved personal hygiene, preventive measures that apply to most of the intestinal protozoa.
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