HIV and Pneumococcal Pneumonia

Today's morning report highlighted the premise that a common presentation of a common problem can still generate a host of learning topics. 

Today’s case was of a 50-year-old man with HIV and AIDS (CD4 count of 8) presenting with fever and dyspnea.  He was adherent to Septra prophylaxis but was not on antiviral therapy.  His chest X-ray was consistent with a consolidative process, and blood cultures were positive for S. pneumoniae.

Learning points from today’s case:

- Pneumonia in an HIV positive patient with a low CD4 count is still more likely to be pneumococcal in etiology than any other

-We discussed the pathophysiology for why infection with encapsulated organisms is still more common in advanced HIV infection.  CD4 cells are helper T-cells which have a role both in cellular immunity (the more commonly implicated deficiency in AIDS) as well as humoral immunity by stimulating B-cells (less commonly mentioned in AIDS).  Encapsulated organisms are eliminated through antibody-mediated opsonization, which also explains why patients with multiple myeloma and functional asplenia are at increased risk.

-We discussed the opportunistic infections that can occur in AIDS.  More specifically, we discussed that Pneumocystis infection is nearly impossible in patients adherent to Septra prophylaxis.  We discussed CNS Toxoplasma infection and how seizures could lead to decreased level of consciousness and aspiration events.  Prophylactic regimens for opportunistic infections based on CD4 count were also discussed.

During your time on our wards (and in medicine as a whole) there are valuable pieces of information regarding any HIV patient that are helpful to collect.  These include mode of infection, duration of infection, current therapy, who follows the patient for his/her HIV, most recent CD4 count/viral load as available, history of opportunistic infections, and prophylaxis.

Further Reading:

Hirschtick, R. E., Glassroth, J., Jordan, M. C., Wilcosky, T. C., Wallace, J. M., Kvale, P. A., ... & Hopewell, P. C. (1995). Bacterial pneumonia in persons infected with the human immunodeficiency virus. New England Journal of Medicine, 333(13), 845-851.