In episode #89 of the Infectious Disease Puscast, Dr. Daniel Griffin and Dr. Sara Dong discuss a range of recent studies from the infectious disease literature. Key viral topics include the durability of antibody responses post-Mpox infection versus vaccination, the effectiveness of a novel oral polio vaccine in newborns, the discovery of the Thogotovirus ("Oz virus") as a cause of fulminant myocarditis in Japan, and the efficacy of Baloxavir in reducing influenza transmission within households.
Bacterial discussions focus on risk factors for mortality in Pseudomonas aeruginosa bloodstream infections and the impact of the 2024 blood culture bottle shortage. They also delve into a study suggesting that common non-antibiotic medications like ibuprofen can promote antimicrobial resistance in E. coli, and another on using preoperative gut microbiome "enterosignatures" to predict surgical site infections. For fungal infections, the hosts review a study linking longer durations of candidemia to worse patient outcomes and rising healthcare costs, and another paper updating the changing epidemiology of blastomycosis and histoplasmosis in the United States, noting their expansion beyond traditional endemic regions. The episode concludes with a parasitic disease study demonstrating that reintroducing African catfish into Lake Victoria is an effective biological control method against the snail vectors of Schistosoma mansoni.
Infectious Disease Puscast #89: A Review of Recent Literature
2:18 Mpox Antibody Durability: A study in Open Forum Infectious Diseases found that antibody responses are sustained for up to two years after an Mpox infection. However, antibody levels decline more rapidly after MVA-BN vaccination, with most recipients losing seropositivity by the two-year mark.
4:36 Oral Polio Vaccine in Newborns: Research published in Clinical Infectious Diseases shows that two doses of a novel oral polio vaccine (nOPV2) administered to newborns in Bangladesh induced strong intestinal mucosal antibody responses. By 8 weeks, 90% of vaccinated newborns showed positive poliovirus neutralization in stool samples, suggesting the vaccine can effectively enhance immunity in this vulnerable population.
6:36 A New Tick-Borne Virus: A report in the New England Journal of Medicine details a case of fatal fulminant myocarditis in a woman in her 70s in Japan. The cause was identified as a novel Thogotovirus, named the Oz virus (OZV), which was discovered in Japanese ticks in 2018.
8:58 Preventing Influenza Transmission: A multi-country Phase 3 trial in the New England Journal of Medicine assessed the efficacy of a single dose of Baloxavir. The study found that treating an infected person with Baloxavir significantly reduced the transmission of laboratory-confirmed influenza to household contacts by about 32% compared to a placebo.
12:24Pseudomonas Mortality Risk: A retrospective study in the journal Infection identified key risk factors for 30-day mortality in patients with Pseudomonas aeruginosa bloodstream infections. Significant factors included older age, the presence of sepsis or septic shock, and high-risk infection sources. The only variable associated with improved survival was the use of appropriate combination empiric antibiotic therapy.
14:24 Blood Culture Bottle Shortage: A study in Clinical Infectious Diseases examined the impact of the 2024 nationwide shortage of BD BACTEC™ blood culture bottles. Facilities using these bottles saw a significant decrease in the number of blood cultures performed, which also led to a decrease in the observed rate of bloodstream infections, raising concerns about patient safety and disease surveillance.
16:12 Non-Antibiotics and Resistance: A study in a Nature journal investigated how commonly used non-antibiotic medications affect E. coli. Researchers found that drugs like ibuprofen and acetaminophen can significantly increase the frequency of mutations that lead to high-level resistance to the antibiotic ciprofloxacin.
19:19 Predicting Surgical Infections with Gut Flora: Published in Open Forum Infectious Diseases, this study introduced the concept of "enterosignatures" to characterize a patient's preoperative gut bacteria. The ratio of Firmicutes to Prevotella bacteria in the gut was found to be a strong, independent predictor of surgical site infections after abdominal surgery.
22:56 Candidemia Duration and Outcomes: A retrospective study in Clinical Infectious Diseases revealed that prolonged candidemia (Candida in the bloodstream) is associated with worse outcomes. For each additional day of candidemia, the odds of in-hospital mortality increased by 3%, along with a longer hospital stay and an average cost increase of over $3,000.
24:50 Changing Fungal Epidemiology: A study using national electronic health records shows that the incidence of blastomycosis and histoplasmosis in the U.S. has increased significantly between 2013 and 2023. The geographic range of these fungal diseases is expanding beyond their historically recognized endemic areas, with significant increases seen in regions like the Upper Midwest for blastomycosis.
28:33 Catfish as Schistosomiasis Biocontrol: A study in PLoS Neglected Tropical Diseases demonstrated an effective, natural way to control the snails that transmit Schistosoma mansoni. By reintroducing the native African catfish into parts of Lake Victoria, Tanzania, researchers observed a 57% decline in the snail vector population and a 55% decrease in the intensity of infection in school-aged children.
Glossary of Terms
Antimicrobial Resistance (AMR): The ability of a microorganism (like bacteria or fungi) to resist the effects of a drug that was originally effective for treating the infection it causes.
Biocontrol (Biological Control): A method of controlling pests, such as insects, mites, weeds, and plant diseases, using other organisms.
Blastomycosis: A disease caused by inhaling the fungus Blastomyces, which is found in moist soil and decaying organic matter.
Bloodstream Infection (BSI): The presence of bacteria or other microorganisms in the blood, also known as bacteremia.
Candidemia: A bloodstream infection with a yeast (a type of fungus) from the Candida species.
Echinocandin: A class of antifungal drugs used to treat serious fungal infections.
Empiric Therapy: Medical treatment initiated based on a clinically educated guess in the absence of complete or perfect information, such as before a definitive diagnosis is known.
Enterosignatures: A way to classify the complex community of microorganisms in the gut into simpler, generalizable patterns based on the dominant types of bacteria present.
Histoplasmosis: An infection caused by inhaling spores of the fungus Histoplasma, which is often found in soil containing bird or bat droppings.
IGG (Immunoglobulin G): The most common type of antibody found in blood circulation. It is a key part of the immune system's response to infection.
Microbiota: The community of microorganisms that live in a particular environment, such as the human gut.
Myocarditis: Inflammation of the heart muscle, which can reduce the heart's ability to pump and cause rapid or abnormal heart rhythms.
Pseudomonas aeruginosa: A common type of bacterium that can cause a range of infections, particularly in hospitalized patients or those with weakened immune systems.
Schistosoma mansoni: A parasitic flatworm that causes schistosomiasis, a disease that affects the intestines and other organs.
Titers: A measurement of the amount or concentration of a substance in a solution, often used to measure the level of antibodies in the blood.
Vaccinia Virus: A large, complex virus belonging to the poxvirus family, which is used as the active component of the smallpox vaccine and is related to the virus that causes Mpox.
Summary of References
Antibody Responses are Sustained 2 Years Post-Mpox Infection but not Following Modified Vaccinia Ankara–Barian Nordic Vaccination: This study compared the longevity of immune responses between individuals who recovered from Mpox and those who were vaccinated. It found that natural infection provides a more durable antibody response, lasting at least two years, whereas vaccine-induced antibodies declined more quickly, with most recipients falling below the seropositivity threshold by the two-year mark.
Intestinal mucosal immune responses to novel oral poliovirus vaccine type 2 in healthy newborns: This clinical trial in Bangladesh evaluated the effectiveness of a new oral polio vaccine (nOPV2) in newborns. The results showed that two doses of the vaccine generated strong intestinal immunity, with 90% of infants showing protective antibody activity in stool samples, indicating its potential to enhance population immunity during outbreaks.
Efficacy of Baloxavir Treatment in Preventing Transmission of Influenza: This Phase 3b trial investigated whether treating a person sick with influenza with the antiviral drug Baloxavir could prevent them from spreading it to household members. Treatment with a single dose of Baloxavir resulted in a 29% relative risk reduction in transmitting the virus to household contacts compared to a placebo.
Fulminant Viral Myocarditis Associated with Thogotovirus: This article reports the first known human case of severe, fatal myocarditis caused by the Oz virus, a type of Thogotovirus. The patient, an elderly woman in Japan, developed symptoms after a tick bite and ultimately died from the infection, which was confirmed through advanced genetic sequencing of heart tissue.
Risk factors for 30-Day mortality and the role of empirical therapy in Pseudomonas aeruginosa bloodstream infections: This Italian multi-center study analyzed outcomes of patients with Pseudomonas aeruginosa in their bloodstream. It identified older age, sepsis, and septic shock as major risk factors for death within 30 days. The only intervention found to improve survival was the initial use of an appropriate combination of antibiotics active against the bacteria.
The Impact of a Nationwide Blood Culture Bottle Shortage in 2024 on Healthcare Facilities in the United States: This study assessed the consequences of a 2024 shortage of blood culture bottles from a major manufacturer. Affected hospitals experienced a significant drop (over 27%) in the number of blood cultures performed, which in turn led to a decrease in the detection of bloodstream infections, highlighting potential risks to patient care and disease monitoring.
The effect of commonly used non-antibiotic medications on antimicrobial resistance development in Escherichia coli: This research explored whether common over-the-counter and prescription drugs could contribute to antibiotic resistance. The study found that medications like ibuprofen and acetaminophen significantly increased the rate at which E. coli developed mutations, leading to high-level resistance to the antibiotic ciprofloxacin.
Preoperative Enterosignatures Predict Surgical Site Infections After Abdominal Surgery: This study investigated a link between a patient's gut bacteria before surgery and their risk of developing a surgical site infection. The researchers developed a novel biomarker, the "Firmicutes-to-Prevotella ratio," which proved to be a strong and independent predictor of which patients were at higher risk for infection after abdominal surgery.
Association between Duration of Candidemia and Clinical and Healthcare Resource Utilization Outcomes: This retrospective study examined the impact of how long a patient has a Candida bloodstream infection (candidemia). The findings show that a longer duration is linked to significantly worse outcomes; each additional day of candidemia increased the odds of death by 3% and added to the length of stay and total hospital costs.
Updating the epidemiology of blastomycosis and histoplasmosis in the United States, using national electronic health record data, 2013–2023: This study used a large national database of electronic health records to provide an updated look at two fungal diseases. It found that the incidence of both blastomycosis and histoplasmosis nearly doubled over a decade and that the geographic areas where these diseases are found are expanding beyond their traditionally known regions.
Stocking African catfish in Lake Victoria provides effective biocontrol of snail vectors of Schistosoma mansoni: This study tested an ecological intervention to control schistosomiasis, a parasitic disease transmitted by freshwater snails. By reintroducing a natural predator—the African catfish—into areas of Lake Victoria, researchers successfully reduced the population of host snails by 57% and decreased the infection intensity in local school-aged children by 55%.