This installment of the "Puscast" provides a concise, opinionated review of infectious disease literature published during the last two weeks of August 2010. The host, Mark Chryslup, leverages the CME-accredited format to discuss several disparate topics, including the correlation between increased rainfall and bubonic plague outbreaks, the widespread latency of JC virus in non-PML patients, and the detrimental long-term immunological consequences of failed initial HIV therapy.
Significant clinical points covered include the observation that low CD4 counts are an independent risk factor for atherogenesis and thrombosis in HIV patients, and a critique of the medical "dogma" surrounding catheter colonization versus infection. The podcast also dismisses the reliability of smear negativity as a proxy for non-infectiousness in tuberculosis and highlights the increased risk of complicated community-acquired pneumonia in patients using NSAIDs. The delivery is frankly self-promotional and demanding, as is typical for the series.
Review of Infectious Disease Literature (Late August 2010)
0:13 Introduction & Accreditation: The podcast marks the beginning of September 2010 and is CME accredited. The host explicitly demands high iTunes ratings for his "fragile ego" and promotes his "Uber hyperlink electronic guide to infectious diseases."
2:25 Climate Change and Plague: Discusses how environmental shifts influence disease incidence. Wet seasons correlate with increased gerbil (rodent) populations carrying Yersinia pestis, leading to subsequent bubonic plague outbreaks. This is supported by historical data utilizing tree rings to track past climates.
4:42 Viral Persistence - Human DNA: Notes that approximately 8% of human DNA consists of ancient Borna virus sequences that have been permanently incorporated.
5:06 JC Virus Latency: Examines the latency of JC virus (cause of PML). DNA evidence was found in 26% of HIV-negative individuals in brain, kidney, and bone marrow samples, indicating the infection is widespread and latent outside the nervous system, ready for immune reactivation.
6:38 HIV Treatment Failure Impact: Failure of initial Highly Active Antiretroviral Therapy (HAART) significantly delays subsequent immune recovery (CD4 > 300 cells). One failure requires 34 months for recovery; three failures require 51 months. Key Takeaway: Success with initial therapy is paramount for immune reconstitution.
8:09 Low CD4 Counts and Atherogenesis: CD4 counts under 500 are identified as an independent risk factor for cerebrovascular accidents (CVA/TIA) and cardiovascular events, separate from antiretroviral toxicity. This is attributed to the chronic pro-inflammatory state induced by persistent HIV infection.
10:09 Dengue Fever Spread: An outbreak among US travelers returning from the Dominican Republic to Minnesota/Iowa demonstrates the risk of local introduction. Dengue is already found in Florida and the Texas border, and global warming may enable its endemic spread as far north as Manitoba, Canada.
11:24 NSAIDs and Pneumonia: Early NSAID use in Community-Acquired Pneumonia (CAP) is associated with a more complicated course (e.g., higher rates of empyema and lung cavitation: 37.5% in NSAID users vs 7% in controls). The host suggests reducing inflammation may inhibit the host’s ability to wall off the infection.
13:54 Catheter Colonization Dogma Rejected: Critiques the term "colonization" for bacteria (e.g., coagulase-negative staphylococci) found in the sterile lumen of dialysis catheters. The study found a 100% progression rate to bloodstream infection within approximately 30 days, especially if the culture time-to-positivity was rapid (<14 hours). Key Takeaway: If a sterile site has bacteria, it is infected.
16:03 Resistant Pneumocystis: High rates of DHPS mutations (conferring sulfa resistance) in Pneumocystis jirovecii (PCP) were found in Lyon, France (33%) compared to Switzerland (7.5%). The epidemiology suggests the resistant strains are primarily spread person-to-person, necessitating improved infection control, especially in waiting areas.
18:36 TB Isolation Duration Challenged: Questions the established dogma that two weeks of therapy renders a TB patient non-infectious. Data showed pan-susceptible TB patients remained culture positive for a mean of 39 days, with 10% remaining positive for 60 days. Smear status alone is not sufficient to determine non-infectiousness.
Rocky Mountain Spotted Fever (RMSF) incidence is increasing, though fatality rates are decreasing.
Ocular syphilis presentation is important to consider, especially in HIV-positive patients and MSM.
Intragastric TMP-SMX prophylaxis for PEG tube infections is as effective as IV Cefuroxime.
Infectious Disease consultation for S. aureus bacteremia decreases mortality and improves resource utilization.
PVL-positive MRSA increases the likelihood of progression to bacteremia.
Prompt and adequate Vancomycin dosing (at least 1g Q12h or 2g/day within 48 hours) improves survival in MRSA infections.
A genetic component may exist for E. coli UTIs, as these infections tend to run in families.
Positive blood cultures are strongly associated with increased crude (20%) and attributable (12%) case fatality ratios.
The use of beta-lactams alone versus in combination with an aminoglycoside for septic bacteremia remains unresolved by current meta-analysis, with conflicting data.