[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

162
CHAPTER 7 Miscellaneous Protozoa
Order
Blastocystida
Class
Blastocystea
Intestinal Species
Blastocystis hominis
FIGURE 7-3 Parasite Classification: Blastocystis hominis.
Now classified as a fungus
Pneumocystis jiroveci
FIGURE 7-4 Parasite Classification: Pneumocystis jirvoeci.
Cytostome
Vacuole
Ingested
microbes
(bacteria)
Micronucleus
Cilia
Macronucleus
A
Size range: 28-152 m by 22-123 m
B
Average size: 35-50 m by 40 m
FIGURE 7-5 A, Balantidium coli trophozoite. B, Balantidium coli trophozoite. (B, from Mahon CR, Lehmann DC,
Manuselis G: Textbook of diagnostic microbiology, ed 4, St Louis, 2011, Saunders.)
Pneumocystis jiroveci (formerly known as Pneumocystis
carinii) is the only member of the fourth
group (Fig. 7-4). This organism was traditionally
included with the Protozoa, even though it has
been recently reclassified as a fungus.
Balantidium coli
(bal’an-tid’ee-um/ko’ly)
Common associated disease and condition
names: Balantidiasis.
Morphology
Quick Quiz! 7-1
What makes each member of the the parasites discussed
in this chapter similar? (Objective 7-11)
A. Presence of cilia
B. They are all unicellular.
C. All are intestinal protozoa.
D. Presence of tachyzoites
Trophozoites. Considered as the largest protozoan
known to humans, the typical Balantidium
coli trophozoite may measure from 28 to
152 µm in length, with an average length of 35
to 50 µm (Fig. 7-5; Table 7-1). The average trophozoite
width is approximately 40 µm but may
range from 22 to 123 µm. The ovoid to sacshaped
B. coli trophozoite tapers at the anterior
end. The organism typically exhibits rotary,