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MANAGEMENT
OF OPPORTUNISTIC INFECTIONS
IN
HIV-POSITIV PATIENTS
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FACT
SHEETS
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AIDS-associated
Diarrhoea
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Multiple
Etiologies
Causative Agents
1. Bacteria : Salmonella, Shigella, Campylobacter
2. Parasitic infections: Cryptosporidium, Isospora, Giardia,
Microsporidia, Entamoeba histolytica
3. Mycobacterial infections: Mycobacterium avium complex
(MAC), Mycobacterium tuberculosis
4. Viral infections: Cytomegalovirus
5. Drug-associated diarrhoea: Certain antiretrovirals
such as protease inhibitors (e.g. nelfinavir)commonly
cause diarrhoea
6. Idiopathic diarrhoea, often labelled 'HIV enteropathy'
Symptoms of active infection
Diarrhoea results from either small intestinal or colonic
pathologic conditions. A careful history and physical
examination will direct the evaluation and treatment strategy
of AIDS-associated diarrhoea. Small-intestinal disease
produces a large volume diarrhoea that is frequently associated
with dehydration and serum electrolyte abnormalities.
Abdominal pain, gaseous distension, nausea and vomiting
also may be present. Tenesmus and fecal leukocytes are
absent.
Colonic diarrhoea is less voluminous, and dehydration
is uncommon. Tenesmus and left lower quadrant pain are
common.
Differential diagnosis
The medical history must elicit the frequency, volume,
colour and consistency of bowel movements.
Bacterial infections
Salmonella, Shigella and Campylobacter cause more severe
diarrhoea with longer duration of illness in the immunocompromised
host.
Parasitic infections
Cryptosporidium, Isospora, Giardia and Microsporidia all
infect the small intestine. Entamoeba histolytica is uncommon
but when present involves the caecum, ascending colon
and terminal ileum. Strongyloides stercoralis may also
be encountered.
Viral infections
Cytomegalovirus (CMV) is the most important viral cause
of AIDS-associated diarrhoea. CMV may affect any part
of the GI tract; colitis and oesophagitis are quite common.
HIV has been cultured from intestinal mucosa when no other
cause of diarrhoea is found, but a causative role in diarrhoea
has not been documented.
Mycobacterial infections
Mycobacterium avium complex (MAC) is found in macrophages
in the lamina propria of the small intestine or colon.
Mycobacterium tuberculosis is most commonly found in the
caecum and terminal ileum.
Treatment |
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Cryptosporidiosis
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No available antibiotic has been
shown to be effective against
cryptosporidium. Paromomycin has been tried with
some success.
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Microsporidia
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Albendazole, 400
mg orally b.i.d, is effective against Enc. intestinalis.
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Isospora
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Trimethoprim-sulfamethoxazole
is effective against Isospora belli.
Recommended dose is 160 mg trimethoprim and 800
mg
sulfamethoxazole orally b.i.d. for 10 days.
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Giardiasis
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Giardia is treated
with metronidazole 500 mg orally b.i.d. for
5-7 days
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Entamoeba histolytica
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Metronidazole, 750
mg t.i.d. for 14 days, is highly effective for
invasive E. histolytica. Use of a luminally acting
agent to eradicate
intestinal colonization is recommended for patients
with invasive
amoebiasis or the asymptomatic "cyst excretor."
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| Mycobacterium avium complex |
Disseminated MAC is treated with clarithromycin
500 mg orally
b.i.d or azithromycin 500-600 mg orally daily, and
ethambutol,
15 mg/kg orally daily. A third or fourth drug selected
from among
rifabutin, ciprofloxacin or parenteral amikacin
may be added for
patients with more severe or extensive symptoms
or disease. |
| Mycobacterium tuberculosis |
Treatment for GI tuberculosis is the
same as that for pulmonary
disease. |
| Cytomegalovirus |
The usual induction dose of intravenous
ganciclovir is
10-15 mg/kg b.i.d. for 3-4 weeks. For those patients
with
frequent relapses of GI disease, long-term once-daily
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| Prophylaxis |
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Cryptosporidium
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In the absence of any drug for
either prophylaxis or treatment of
cryptosporidiosis, prevention of exposure is extremely
crucial. HIV- infected persons should be advised
to avoid ingestion of
contaminated food and wash hands after handling
soil or pets.
Boiling water for one minute or use of sub-micron
water filters
eliminates the risk of cryptosporidiosis.
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Isospora belli
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Recommendations for
prevention of exposure to Isospora are
similar to those of Cryptosporidium as described
above. Treatment
with trimethoprim-sulfamethoxazole is highly effective.
However,
relapses occur in 50% of patients. Hence maintenance
therapy
with trimethoprim-sulfamethoxazole one double
strength tablet
once daily or three times weekly for continued
suppression is
recommended. In patients who are intolerant to
sulphonamides,
weekly sulfadoxine-pyrimethamine or pyrimethamine
alone may
be used.
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