Eravacycline: The Next Frontier in C diff Treatment?

More research into eravacycline as a treatment options for patients with a history of Clostridioides difficile (C diff) is warranted after the agent offered a protective effect, according to a poster presented during IDWeek 2019. It may also be useful for patients who acquire other infections and are at a higher risk for developing C diff infection.

Investigators from the University of Houston College of Pharmacy conducted a prospective study in order to analyze the occurrence of C diff infection in patients with community-acquired pneumonia, if their treatment included doxycycline. The study team wanted to assess the in vitro susceptibility of eravacycline compared to other commonly-used antibiotics against C diff isolates, including those isolates with decreased susceptibility to metronidazole and vancomycin.

In general, tetracycline antibiotics are considered an antibiotic with low risk for causing C diff, the study authors noted. For example, tigecycline is known to decrease toxin production, inhibit spore formation, and have clinical efficacy in patients with severe and severely complicated C diff infection, they continued. However, the use of tigecycline in clinical practice is limited due to its multiple known toxicities. Conversely, eravacycline has a more favorable safety profile.

The investigators collected 234 isolates from their biobank and divided the samples into groups of 37-42 isolates per C diff ribotype. The 6 most common ribotypes were F001, F002, F014-020, F027, F106 and F255, they said. The investigators measured the minimum inhibitory concentration (MIC) for eravacycline, vancomycin, metronidazole and fidaxomicin against all of the ribotypes.

Overall, eravacycline was more efficient against more common isolated ribotypes from the biobank compared to vancomycin and metronidazole, the study authors found. The MICs values of eravacycline were consistent across all of the ribotypes in the investigators tested, they said.

There were low eravacycline MICs seen, even in strains with high MICs to vancomycin and metronidazole, the investigators determined. The study team made sure to highlight that vancomycin MICs have never correlated with C diff infection treatment failure, since vancomycin reaches such high colonic concentrations.

Instead, high vancomycin MICs are correlated with hypervirulent strains, and these results indicate that eravacycline still displays low rates of cross-resistance, Anne Gonzales-Luna, PharmD, research assistant professor at University of Houston College of Pharmacy, explained to Contagion®.

“Tetracyclines have known to have a protective effect against C diff infection development because of their activity against the C diff bacteria, and our results agree with this paradigm,” Gonzales-Luna continued. “We don’t encourage eravacycline use as a treatment for C diff infection at this time but rather as a good option for the treatment of other infections in patients with a history of C diff infection or at a high risk of C diff infection development.

“Further development of eravacycline as a C diff antibiotic may be warranted based on these results,” she concluded.

The poster, titled “In vitro Activity of Eravacycline, a New Tetracycline Analog, and Comparators Against the Six Most Commonly Isolated Ribotypes of Clostridioides difficile,” was presented in a poster session on Thursday, October 3, 2019, at IDWeek 2019 in Washington DC.