A microbiota-based live biotherapeutic for treating recurrent Clostridioides difficile infection (rCDI) remained effective after subsequent antibiotic exposure, researchers reported this week in Open Forum Infectious Diseases.

In a post-hoc analysis of a phase 2 trial evaluating the safety, efficacy, and durability of Rebyota fecal microbiota transplantation for preventing rCDI, the researchers evaluated patients who received non-CDI antibiotics for up to 2 years after Rebyota administration. Although Rebyota has been found to be highly effective in preventing rCDI and was approved by the US Food and Drug Administration in December 2022, the researchers wanted to assess the durability of the treatment response, particularly in patients subsequently exposed to antibiotics, which can disrupt the gut microbiome and increase the risk of rCDI. They looked specifically at non-CDI antibiotics, because any recurrence of CDI would require antibiotic treatment.

Treatment response was defined as the absence of CDI diarrhea needing retreatment as of the last evaluable time point (8 weeks, 6 months, 1 year, or 2 years) after Rebyota administration.

Durable response

Of the 149 participants in the trial, 43 received non-CDI antibiotics after Rebyota administration over a 2-year period. Across all evaluable time points, 37 of 43 (86%) had treatment response regardless of when non-CDI antibiotic exposure occurred, with treatment response rates ranging from 83% to 96% at the various time points. 

Among participants with treatment response, success was sustained for a median of 470 days from the first initial non-CDI antibiotic use. Of the six participants who experienced rCDI, 5 received a high-risk antibiotic. 

Although the study was limited by lack of a control group and other factors, the researchers say the findings provide evidence that Reboyota offers durable protection after antibiotic exposure in a real-world population.

"Irrespective of the inherent limitations of this analysis, these results suggest RBL [Rebyota] may restore the gut microbiota to a sufficient threshold protective against rCDI for many patients despite subsequent non-CDI antibiotic use," they wrote.

For the first half of 2024, dengue cases in the Americas region have already surpassed yearly maximums, and cases have already doubled those of 2023, the Pan American Health Organization (PAHO) said this week in its latest epidemiologic update.

So far more than 9.3 million cases have been reported by 43 countries and territories. About half were lab confirmed. Of the total, 9,592 were severe and 4,529 were fatal. Six countries accounted for nearly all the deaths: mostly Brazil, followed by Argentina, Peru, Paraguay, Colombia, and Ecuador.

Compared to both 2023 and 5-year case averages, cases were up most sharply in the Caribbean region, followed by the Southern Cone, Central America and Mexico, and Andean-region countries. 

All 4 serotypes circulating

All four dengue virus serotypes have been circulating in the Americas, with levels varying by country. All four are circulating simultaneously in Brazil, Costa Rica, Guatemala, Honduras, Mexico, and Panama.

The agency urged countries to continue their surveillance, diagnosis, treatment, and vector control activities. PAHO also said clustering of cases is also common with diseases including dengue, chikungunya, and Zika. "Efforts should be made to analyze the spatial distribution of cases to enable a rapid response at the local level in the most affected areas," it said. "Information from the hotspots of the three diseases should be targeted for intensive vector control."

China has reported another fatal human infection involving H5N6 avian flu, its third of the year, according to an avian influenza update from the World Health Organization (WHO) Western Pacific regional office. 

The patient is a 41-year man from Fujian province in the country's southeast whose symptoms began on May 8. He had severe pneumonia and was hospitalized, where his respiratory samples tested positive on May 14. He died from his infection. The report did not say how the man is thought to have contracted the virus.

China's last H5N6 case, reported in May, was also from Fujian province and likewise fatal. 

H5N6 is known to circulate in poultry in China and a few other Asian countries. Infections in humans are often severe or fatal. So far only China and Laos have reported H5N6 cases in people. The WHO said the man's illness raises the number of H5N6 cases to 92 and the fatality total to 37. 

Today in Morbidity and Mortality Weekly Report, authors describe the distribution of the antiviral drug tecovirimat (Tpoxx) in Los Angeles County during the 2022-23 global mpox outbreak, which was spread largely among men who have sex with men.

Los Angeles was one of the epicenters of the mpox outbreak in the United States, and public health officials quickly developed a hub-and-spoke distribution model to deliver the antivirals to those who had been exposed to the virus, consisting of 44 hub facilities serving 456 satellite sites across the county, with two-thirds being clinics or pharmacies. 

This strategy was built on the COVID-19 vaccine rollout.

"This strategy was built on the COVID-19 vaccine rollout, for which clinics and pharmacies were crucial to vaccine distribution networks," the authors said. 

Median time to treatment was 2 days 

Thirty-nine percent of all California mpox cases occurred in Los Angeles County, the most populous county in the state. By January 31, 2023, 2,281 patients with mpox were reported in the county, and approximately one-third (735; 32%) had been treated with tecovirimat.

"120 (16%) patients who received tecovirimat were treated at pharmacies, 227 (31%) at hospitals, and 388 (53%) at community clinics," the authors wrote. The median interval from specimen collection to treatment was 2 days, and the average patient age was 38.

"Overall, the distribution strategy was effective and sufficient to meet increasing needs. Similar strategies might benefit tecovirimat distribution in different jurisdictions as would other prepositioned therapeutics for mpox or future emerging infections," the authors concluded.