Diarrhea and HIV

Today we discussed diarrhea in the setting of HIV.

As a general rule, whenever faced with a new (or worsened) problem in the setting of a pre-existing disease, a useful dichotomy is whether this new problem is related or unrelated to the underlying disease. Pts with underlying HIV are still "entitled" to have the more common causes of diarrhea (or any other presentation)

Diarrhea, weight loss, malnutrition, and wasting was interestingly one of the first described syndromes of what came to be known as AIDS in 1985; it was initially called "slim disease" by African populations, as this Lancet article describes

Clinically significant diarrhea occurs in about 50% of HIV-infected patients in North America. The majority of these patients have an identifyable enteric pathogen if extensive enough workup is done. There is a small subset of HIV patients with "HIV enteropathy", in whom there is no identifyable pathogen. This is likely due to the effect of HIV itself and inflammation involving the GI lymphatic tissue.

Diarrhea may be more characteristic of small bowel pathology (post-prandial, voluminous, associated with weight loss and malnutrition) or large bowel pathology (frequent, small volume, with possible blood and mucous, tenesmus).

One way to approach the MANY opportunistic and other causes of diarrhea is by CD4 count:

Any CD4 count:
Bacterial: C. Diff, salmonella, shigella, campylobacter
Mycobacterial: M. TB
Parasitic: strongyloides, cyclospora, isospora, entamoeba histolytica, giardia lamblia

CD4 below 200: all of above and
Histoplasma capsulatum
Coccidioides

CD4 below 100: all of above and
Cryptosporidium (shown above)
Microsporum
Leishmaniasis

CD4 below 50: all of above and
MAI
Cryptococcus
CMV

Treatment is generally targeted at the identified pathogen. See Table 3 in below paper for details on specific agents for each of above.
Non-specific treatments include anti-diarrheals, low fat diet, nutritional support, and avoidance of lactose

Link:
Click here for a 2009 review from Gastroenterology on HIV and diarrhea (need journal access)

HIV+ with Shortness of Breath

(a complex parapneumonic effusion pictured left)

Today we discussed the diagnosis and management of Parapneumonic Effusions. Check out some details here.

We also discussed an approach to patients with HIV who present with shortness of breath.

A few things to consider...

• Is this an HIV or non-HIV related condition?
• What is this patient's immune status (last CD4+ count and Viral Load)
• Is this patient on Antiretroviral therapy?
• Is this patient taking the appropriate prophylactic therapy (eg. Septra for PJP)
  
• Are there other Tuberculosis risk factors?
• Can the past medical history help me here?

HIV-related causes of shortness of breath:

1. Infectious

• Community acquired pneumonia: >10x more likely in HIV + patients with CD4+ counts less than 200. Watch out for parapneumonic effusions and empyema. S. pneumoniae is common.
  
• Pneumocystis Carinii Pneumonia or Pneumocystis Jirovecii Pneumonia or PCP or PJP... whatever you want to call it, this is still the most common AIDS-defining opportunistic infection. You can read more on this here.
• Viral: Influenza, CMV
• Tuberculosis must be considered, but also think about non-tuberculous mycobacteria as well, like MAC (usually disseminated rather than pulmonary)
  
• Fungal: Cryptococcus, Histoplasma, Coccidioides. Also think about Aspergillus - though more common in neutropenia.

2. Malignant:

• Lymphoma: non-Hodgkins > Hodgkins
  
• Kaposi's sarcoma and associated Castleman's Disease
• Metastatic disease
  

3. Other:

• Cardiovascular: think about cardiomyopathy or other cardiac risk factors associated with HIV as a cause for shortness of breath
• Pulmonary Hypertension
• Drug toxicity
  
• Inflammatory conditions

A Good Link:

• Here is a great case and approach to shortness of breath in HIV+ individuals.
  

There is the artist formerly known as Prince...

....and the pneumonia formerly known as Pneumocystis Carinii Pneumonia. Many people still refer to it as PCP , but you will also hear it called Pneumocystis Jirovecii Pneumonia (PJP). Either is fine. It is a common respiratory opportunistic infection in HIV+ individuals. Those with a CD4 count less than 200 are at the greatest risk. It is a protozoa, and is found ubiquitously in soil - we are all exposed, but this organism poses few problems to healthy immune systems.

The classic clinical presentation is dyspnea with subacute onset, and a dry cough. Patients may have a low-grade fever, tachycardia, and tachypnea. The chest exam is variable - you may hear crackles...you may have a normal exam (in up to 50% of cases). The Chest X-ray often reveals bilateral interstitial infiltrates, but virtually any abnormality may be seen.

Remember, we can make the diagnosis roughly 90% of the time with history and physical exam alone. Still, it is nice to confirm your diagnosis by isolating an organism. Methenamine silver or Immunofluorescent stains on induced sputum (or bronchoalveolar lavage) has a high sensitivity and specificity.

Treatment: TMP-SMX in high doses. This has some interesting complications associated with it (see below). If patients are allergic to sulfa drugs or have complications, other agents can be used, such as TMP-Dapsone, or Atovaquone.

Steroids? Yep. If the PaO2 is less than 70, this is very helpful. Of note, this was a major breakthrough in medicine and was discovered by local talent here in Toronto.

What else? Watch these patients closely. There is often a profound inflammatory reaction to the dying organisms, and patients often get worse on day 2-ish of treatment. That is why the steroids are added in severe disease.

Links:

• Treatment guidelines for HIV can be found here.
• Treatment guidelines for Opportunistic infections are here.
• A great review of PCP from NEJM here.
• Local talent publishing on an interesting complication from high dose trimethoprim-sulfamethoxazole.
  

Below: Methenamine silver (top) and Immunofluorescent (bottom) stains on induced sputum showing PCP.