Infection and Lupus
As is often the case when I write a blog, this one was spurred by a post I read on another lupus site. The issue was infection in patients with SLE. I found an excellent article which addresses this subject. The article, written for physicians who need to accrue credits in continuing medical training, appeared on the Medscape website (http://www.medscape.org/viewarticle/767113)
Some important highlights of this article are:
1) So-called opportunistic infections occur at a higher rate in lupus patients than in the general population. This is mostly due to the fact that people with lupus are on immunosuppressive therapy. The severity of infection and immunosuppressive therapy are strongly correlated.
2) Increase in opportunistic infection is not only due to immunosuppressive therapy; it also seems to arise from the fact that there is something inherently amiss with an SLE patient’s immune system. The immune aberrations, which are hallmarks of SLE, heighten susceptibility to infection.
3) As result of the two risk factors for infection listed above, the European League Against Rheumatism has recommended that all people with SLE be screened for several infectious agents before immunosuppressive therapy is begun. These agents are: hepatitis C virus, hepatitis B virus, cytomegalovirus and HIV. Additionally, if there is a high incidence of M tuberculosis in the patient’s community, then a screen for that agent should also be run.
4) The most common infectious agents (that cause illness) in SLE patients are: E coli, S aureus, M tuberculosis and S pneumoniae.
5) The Medscape article states that fungal infections are rare in SLE patients
6) One of the tests (serum procalcitonin levels) usually run by a doctor to detect the presence of infection is not useful in SLE patients. According to the Medscape article, both infected and non-infected SLE patients will likely show normal procalcitonin levels.
7) Another test, C reactive protein, which is ordinarily run to detect inflammation or infection, also is not a good tool in lupus patients. Patients with SLE will likely get an elevated C reactive protein result whether or not they are ill.
One thing the Medscape article emphasizes is that a physician cannot rely on the usual diagnostic tests to detect infection in SLE patients. The article suggests that a distinct set of tests must be developed for patients who have SLE. With this subset of patients, in which an infection can have especially devastating effects, more accurate and timely detection of infection should become a clinical priority.