Case # 1. A 19 year old African American man who presents with a recent history of proven HSV encephalitis treated with 21 days of intravenous acyclovir presented with recurrent neurological symptoms and worsening brain MRI findings secondary to recurrent versus refractory HSV.
From: http://posterng.netkey.at/esr/viewing/index.php?module=viewimage&task=&mediafile_id=508165&201302022314.gif
1. In most HSV encephalitis cases, 21 days of acyclovir may be enough. However, in cases where the initial infection is severe, like in this patient with extensive edema of the temporal lobe and serious neurological manifestations, treating for more than 21 days may be beneficial. We can learn from how our Pediatric Infectious Disease group here treat neonatal HSV encephalitis. On the 19th day of acyclovir treatment, a repeat lumbar puncture is performed and HSV PCR is rechecked from the CSF. If this comes back positive for HSV, treatment is extended for another 1-2 weeks.
2. Relapses of HSV encephalitis are usually seen in the pediatric age group, especially in those patients treated with only 10 days of acyclovir.
3. Interestingly, another differential diagnosis for a patient with relapsing symptoms after treatment of HSV encephalitis is anti-NMDA receptor encephalitis! Infection with HSV in the brain triggers the production of NMDA receptor antibodies that are responsible for this syndrome. Read more here. This is not the case here as our patient has a positive CSF HSV PCR on readmission.
4. Anti-NMDA receptor encephalitis is an autoimmune disorder usually seen among young women with an ovarian teratoma that is characterized by prominent psychiatric manifestations, autonomic instability, mutism, memory deficits, and dyskinesias (read here for a good review). Every infectious disease physician should know this diagnosis as its prevalence now surpasses that of viral encephalitis in the California Encephalitis Project cohort (read here). Anti-NMDA encephalitis is treated with steroids.
4. Recurrent HSV encephalitis merits a work-up for immunodeficiency. Toll-like receptor 3 (TLR3) deficiency and NK cell deficiency predispose patients to developing recurrent HSV encephalitis.
Case # 2. A 20 month old child presented with a 3-day history of an ulcerating lesion in the nose secondary to ecthyma gangrenosum as a result of Pseudomonas aeruginosa infection.
From: http://www.langetextbooks.com/0071774343/gallery/035_ch18.jpg
1. Ecthyma gangrenosum is not exclusive to Pseudomonas. Staphylococcus aureus, other gram negative bacteria, and fungi are also known to cause it.
2. Ecthyma gangrenosusm starts out as a painless macule. It then rapidly develops induration and becomes pustular (sometimes bullous). Later on, it ulcerates and becomes gangrenous (with a central black eschar). The final appearance (as shown in the picture) is a lesion with a necrotic center surrounded by a usually raised red or violaceous border. The evolution from a macule to a necrotic ulcer typically takes 12-18 hours!
Case # 3. A 68 year old man with pure red cell aplasia of undetermined cause, history of recent alemtuzumab treatment, who presented with fever, chest pain, and pulmonary infiltrates associated with a pleural effusion secondary to Actinomyces naeslundii.
1. Alemtuzumab is an anti-CD52 monoclonal antibody used in many refractory lymphoproliferative diseases and autoimmune conditions. It causes a profound depletion of T cells that lasts for many months. Its use has been associated with development of a variety of opportunistic (especially CMV, PML, adenovirus, toxoplasmosis) and non-opportunistic infections (e.g. bloodstream infections). Read more here.
2. We often think of actinomycosis when the infection is said to spread beyond tissue planes. Well, if caught early, like in this case, we can just sometimes appreciate localized disease (in this case, empyema without chest wall extension).
3. Remember that even if Actinomyces is an anaerobic bacteria, it is resistant to metronidazole.
No comments:
Post a Comment