The podcast "Infectious Disease Puscast #82," hosted by Drs. Daniel Griffin and Sara Dong, provides a comprehensive review of recent infectious disease literature from May 22 to June 4, 2025. Key discussions span viral, bacterial, fungal, parasitic, and miscellaneous topics. Highlights include the projected averted cases of Congenital Rubella Syndrome due to universal rubella vaccination, the low clinical impact of HIV superinfection in HIV D+/R+ kidney transplants, and the under-recognition of RSV as a healthcare-associated infection. The hosts also delve into the emergence of Francisella tularensis in beluga whales, the concerning long-term persistence of macrolide resistance following azithromycin mass drug administration, and successful antibiotic de-escalation protocols for febrile neutropenia. Fungal discussions cover the high prevalence of Histoplasma antigenuria in advanced HIV patients and new guidance for dimorphic fungal diagnostics. Parasitic topics include a fatal Naegleria fowleri infection from nasal irrigation with RV water and evidence for local transmission of fishborne trematodiases in the US. Finally, novel findings on effective respiratory etiquette (coughing into the shirt) and a new compound for bed nets that targets malaria parasites in mosquitoes (bypassing insecticide resistance) are presented.
Infectious Disease Puscast #82: Highlights from Recent Literature (Weeks of 5/22 - 6/4/25)
2:19 Congenital Rubella Syndrome (CRS) Incidence and Vaccination (MMWR): Rubella infection in early pregnancy can cause miscarriage, fetal death, or birth defects known as CRS. A modeling study estimates that in 19 countries without a Rubella-Containing Vaccine (RCV) program, where 24,000 CRS cases occurred in 2019, universal RCV introduction from 2025-2055 could avert approximately 986,000 CRS cases. The WHO now recommends universal RCV introduction in these countries to accelerate global elimination.
4:06 HIV Superinfection in HIV D+/R+ Kidney Transplants (JID): Transplantation of kidneys from HIV-positive donors to HIV-positive recipients (HIV D+/R+) has been shown to be safe and effective, but carries a unique risk of donor-derived HIV superinfection (acquiring a new genetically distinct strain). A study of 18 kidney transplant recipients identified only one confirmed case of HIV superinfection at 26 weeks, which resulted in no clinically significant changes, suggesting it is rare and has negligible clinical impact in this context.
6:30 Respiratory Syncytial Virus (RSV) as an Under-recognized Healthcare-Associated Infection (Infection Control and Hospital Epidemiology): Traditional definitions of healthcare-associated RSV (positive test after hospital day 3) likely underestimate its true incidence. By including patients who tested positive within the first 3 days of hospitalization and were recently transferred from post-acute care facilities or recently discharged from acute care for a non-RSV illness, an additional 95 cases (10.6% of all RSV-related hospitalizations) were identified, compared to 41 cases (4.6%) by the traditional definition. This highlights the need for broader surveillance to inform infection prevention.
8:54Francisella tularensis in Stranded Beluga Whales, Alaska (CDC: Emerging Infectious Diseases): Fatal tularemia caused by Francisella tularensis subspecies holarctica was identified in stranded beluga whales in Cook Inlet, Alaska. The pathology indicated the pulmonary form of the disease, suggesting inhalation of contaminated water (possibly from brackish Cook Inlet or freshwater runoff) as the likely route of exposure. This finding has implications for biosecurity and marine mammal health in the North Pacific.
12:28 Long-term Effects of Azithromycin Mass Drug Administration (MDA) on Streptococcus pneumoniae Antimicrobial Resistance (AMR) (Lancet Infectious Diseases): A 3.5-year follow-up study after the MORDOR trial (mass azithromycin administration to reduce childhood mortality) in Malawi found that macrolide resistance in S. pneumoniae significantly increased from baseline (~21.7%) to ~32.1% in azithromycin-treated clusters and persisted. Resistance also increased in placebo-treated clusters (~21% to ~30.9%) and was found in children born after the MDA ended, suggesting persistence and potential spread to untreated populations. This contrasts with some prior studies that showed resistance returning to baseline post-MDA and raises public health concerns.
19:25 Reducing Inappropriate Antibiotic Use in Febrile Neutropenia (Infection Control and Hospital Epidemiology): Implementation of a structured antibiotic de-escalation protocol for hematology patients with febrile neutropenia (e.g., stopping antibiotics after 96 hours if afebrile for 48 hours and cultures are negative) effectively reduced inappropriate antibiotic use. Rates decreased from a baseline of 45.5-66.7% per month to a median of 23.35% post-intervention, without increasing adverse outcomes like in-hospital mortality or Clostridioides difficile infection.
22:05 Optimizing Cefazolin Dosing for Central Nervous System (CNS) Infections (Antimicrobial Agents and Chemotherapy): Historically, cefazolin was believed to have poor blood-brain barrier penetration, but recent evidence suggests it can achieve adequate CSF and brain tissue concentrations for MSSA CNS infections. Monte Carlo simulations indicate that the standard 2g IV Q8H dosing may be insufficient, and a continuous infusion (e.g., 12g over 24 hours) might be optimal, especially for isolates with higher MICs. Clinicians should also consider the impact of albumin levels (due to high protein binding) and the potential for a cefazolin inoculum effect.
25:29Histoplasma Antigenuria in Advanced HIV, Côte d’Ivoire (CID): An ancillary study in Côte d’Ivoire (part of the STATIS trial) analyzed urine samples from ambulatory, newly diagnosed advanced HIV patients (CD4 <100) and found a Histoplasma antigenuria prevalence of 24.3%. This prevalence was comparable to that of tuberculosis, and histoplasmosis was identified as a potential cause of preventable deaths in this cohort, highlighting the urgent need for screening strategies in sub-Saharan Africa.
26:54 Interferon-γ Therapy for Refractory Disseminated Coccidioidomycosis (CID): A review of 17 cases reported favorable responses to adjunctive interferon-γ therapy in most patients with refractory disseminated coccidioidomycosis. However, patients with STAT1 gain-of-function mutations ultimately failed treatment, indicating that underlying genetic conditions can significantly impact therapeutic efficacy.
29:59 Practical Guidance for Dimorphic Fungal Infection Diagnostics (Clinical Microbiology Reviews): This comprehensive review provides a centralized document on antibody and antigen detection methods for diagnosing dimorphic fungal pathogens (e.g., Blastomyces, Coccidioides, Histoplasma, Paracoccidioides, Sporothrix, Talaromyces marneffei). It summarizes assay accuracy, discusses nuances and caveats for microbiology teams and clinicians, and offers expert recommendations, including algorithms for test utilization and interpretation (e.g., concurrent serum/CSF antibody and urine antigen testing for Histoplasma).
32:41 Primary Amebic Meningoencephalitis (PAM) and Nasal Irrigation with RV Water (CDC: MMWR): A fatal case of PAM, caused by Naegleria fowleri, occurred in a 71-year-old woman in Texas who used tap water from her recreational vehicle (RV) for nasal irrigation. While N. fowleri was not isolated from the RV or campsite water systems (sampled 23 days later), the water systems showed suboptimal disinfection. The case underscores the severe health risks associated with improper nasal irrigation practices and the importance of maintaining RV water quality.
34:50 Plausible Transmission of Fishborne Trematodiases in the US (JID): The widespread introduction of an intermediate host snail (Melanoides tuberculata) and the fishborne trematodes it transmits (Haplorchis pumilio and Centrocestus formosanus) in the US, combined with findings that commonly caught US game fish carry human-infectious trematode stages (metacercariae), suggests a plausible risk for local transmission. An online social media search revealed that people in the US consume these fish species raw and unfrozen, reinforcing the need for public health awareness, as freezing fish prior to raw consumption is crucial for prevention.
40:53 Pilot Study: Coughing into the Shirt to Disrupt Respiratory Pathogen Transmission (International Journal Of Emergency Medicine): A pilot study involving five healthcare workers found that coughing into one's shirt significantly reduced the maximal respiratory plume area by 95.4% compared to an unobstructed cough. This maneuver was found to be comparable to, or potentially more effective than, coughing into an elbow or a mask in containing respiratory plumes, although significant individual variability in plume generation was observed among participants.
47:05 New Compound for Bed Nets Targets Malaria Parasites, Not Mosquitoes (Nature): Researchers identified chemical compounds (endochin-like quinolones, or ELQs) that, when applied to insecticide-treated bed nets, block malaria parasite transmission. These compounds kill malaria parasites within mosquitoes upon contact, rather than killing the mosquitoes themselves, thereby circumventing the issue of insecticide resistance. The top two compounds retained activity for over a year, offering a novel strategy for malaria control.