[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

CHAPTER 3 The Amebas
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an accurate diagnosis may be made, but also
before experimental treatments can be administered
and studied. There is some evidence to
suggest that sulfamethazine might be a suitable
treatment. Cases of Acanthamoeba keratitis have
successfully been treated with several medications
that include itraconazole, ketoconazole,
miconazole, propamidine isethianate, and
rifampin. Of all these agents, propamidine
appears to have the best documented success
record. The key to successful treatment to eye
infections is to begin treatment immediately once
the infection has been diagnosed.
graft procedure. In this case, the patient subsequently
developed osteomyelitis.
Several newer testing methods (see Chapter 2)
aimed at differentiating the strains of Acanthamoeba
have been studied, including monoclonal
antibodies and flow cytometry. In addition, DNA
RFLP tests have been performed to aid in taxonomic
classification of Acanthamoeba spp.
Although additional testing with all these techniques
has been suggested, available tests have
shown promising results.
Prevention and Control
Strategies designed to keep individuals from contracting
Acanthamoeba CNS infections are difficult
to determine because the life cycle of this
ameba is poorly understood. However, eye infections
with Acanthamoeba may be prevented primarily
by following all manufacturer-established
protocols associated with the use of contact
lenses. One of the most important protocols for
contact lens wearers is to avoid using homemade
nonsterile saline solutions.
Notes of Interest and New Trends
Acanthamoeba shares many characteristics with
the gram-negative bacteria Pseudomonas aeruginosa,
which frequently occurs in standing water
as an eye pathogen, but they are usually not
recovered simultaneously from the same patient.
It is believed that P. aeruginosa inhibits the activity
of Acantha moeba spp.
Acanthamoeba has been rarely known to
infect areas of the body other than those typically
reported. An interesting case involved cutaneous
lesions filled with Acanthamoeba trophozoites
and cysts on the trunk, legs, and arm of a patient
suffering from AIDS. The patient also presented
with brain lesions that did not show the Acanthamoeba
organisms. Another case involved
Acanthamoeba invasion of bone following a
Quick Quiz! 3-26
The term acanthopodia refers to: (Objective 1)
A. Spinelike pseudopods
B. Hairy projections
C. Double-layer cell wall
D. Large karyosome and no obvious peripheral
chromatin
Quick Quiz! 3-27
The specimen of choice for diagnosing Acanthamoeba
species trophozoites and cysts is which of the
following? (Objective 3-8)
A. Urine
B. Sputum
C. Cerebrospinal fluid
D. Stool
Quick Quiz! 3-28
Humans may acquire Acanthamoeba species by
which of the following? (Objective 3-5B)
A. Aspiration or nasal inhalation of the organisms
B. Direct invasion of the parasites in the eye
C. Swimming or bathing in contaminated water
D. A or B