This Infectious Disease podcast, covering literature from early August 2015, addresses diverse topics ranging from microbial ecology in space to clinical ID management. Key findings include the concerning increase in antibiotic resistance observed in bacteria exposed to microgravity on the ISS, and the identification of two specific spike protein mutations enabling MERS-CoV to infect human cells—a clear case of rapid evolution. Clinically, the podcast highlights that high Ebola mortality rates in Sierra Leone correlate directly with delayed care (4.5 vs. 6.3 days presentation), and reiterates the critical need for smoking cessation in HIV patients due to severe cardiovascular risk. The speaker notes evidence supporting the safety of VZV vaccine in low-dose steroid users. Further topics cover the transient acquisition of multi-drug resistant Enterobacteriaceae following tropical travel and data supporting long-term suppressive antibiotics for certain prosthetic joint infections. The speaker is highly critical of the $2,900 cost for a 5-day course of the antibiotic Arida Vansen, deeming it an egregious overcharge for a mediocre drug.
Summary of Infectious Disease Podcast (August 2015)
0:55 Bacteria in Space: The International Space Station (ISS) is contaminated (Staff, Legionella, Pseudomonas). Microgravity exposure appears to reduce bacterial virulence but paradoxically increases antibiotic resistance (e.g., Vancomycin MIC for Staph) due to cell wall thickening, posing a risk for deep space missions.
2:41 Isolation Protocols: Universal use of gowns and gloves in the ICU did not lead to increased adverse patient complications, contrasting with prior ward studies. This success is likely due to better nurse-to-patient ratios in the ICU.
4:01 Ebola Clinical Factors: In Sierra Leone, survivors sought care significantly faster (mean 4.5 days) than non-survivors (6.3 days), suggesting mortality is heavily influenced by infrastructure and late presentation. Crucially, 18% of patients presented without fever.
5:53 Climate Change and Dengue: Satellite data from Peru links maximal Dengue transmission to hot, humid weather. Based on global warming projections, Dengue could spread significantly further north (e.g., Montreal).
7:04 MERS Evolution: The ability of MERS-CoV to infect human cells (rather than just bats) is attributed to two specific mutations in the spike protein, allowing activation by human proteases. This is presented as "evolution in action," not luck.
8:17 HIV and Smoking: Due to significantly increased life expectancy for HIV patients, smoking cessation is now critical. Having HIV independently increases the risk of progressive atherosclerosis, but smoking remains the dominant cardiovascular risk factor.
9:49 VZV Vaccine Safety: Data now supports the safety of administering the VZV (shingles) vaccine to patients on low-dose steroid therapy (≤ 20 mg/day Prednisone), confirming previous expert opinion.
10:49 Leptospirosis Risk: An outbreak in Swiss river surfers serves as a reminder that leptospirosis should be considered in the differential diagnosis for patients reporting exposure to any fresh water source.
14:49 Mitral Valve Prolapse (MVP): MVP is identified as a risk factor for streptococcal endocarditis, while hereditary thrombophilias (Factor 5 Leiden, Prothrombin mutation) were not found to increase endocarditis risk.
15:31 Travel-Acquired MDR Organisms: Travel to tropical areas, particularly Asia (72%), is associated with the transient acquisition of multi-drug resistant Enterobacteriaceae (MRE). However, carriage rates drop sharply, with persistence down to 4.7% after three months.
17:41 Orthopedic Infections: Bacteriuria prior to elective hip replacement is merely a marker of debility, not a causative factor for PJI. Prophylactic antibiotics for concurrent GU procedures do not decrease the risk of subsequent PJI.
19:16 Vertebral Osteomyelitis (VOM) Duration: A randomized study suggests no difference between 6 weeks and 12 weeks of treatment for VOM (non-MRSA). I remain highly skeptical of using only 6 weeks for MRSA VOM and reject the use of oral therapy entirely, given that "it's difficult to remove a spine."
21:20 Prosthetic Joint Infection (PJI) Suppression: Long-term suppressive antibiotics (minimum six months) for Staph/MRSA PJI treated with poly exchange demonstrably increase the time the joint remains functional. This validates my existing clinical practice.
22:03 Ebola Screening Criticism: Ongoing follow-up of travelers from West Africa is deemed unproductive "medical theater," intended to satisfy non-clinical organizational demands while generating unnecessary work for clinicians.
23:16 Arida Vansen Cost: The antibiotic Arida Vansen, described as a mediocre drug, carries an absurd acquisition cost of $2,900 for a 5-day course. Such pricing is irrational and will obviously limit its use, as far as I can tell.