Antibiotic Alternative for R. Equi Prophylaxis

Researchers at Texas A&M University and the University sity of antibiotic-resistant genes in the bacteria. Most of Georgia found that gallium maltolate (GaM), a semialarming was the discovery that the bacteria were resismetal compound with antimicrobial and anti-inflammatant to multiple drugs and antibiotics. The GaM-treated tory properties, could be a viable alternative to overpreand control groups showed no change in the number or scribed antibiotics for Rhodococcus equi pneumonia. diversity of resistance genes, a positive finding.

Current methods to screen for R. equi are imprecise The team also experimentally infected soil plots and many foals are given prophylactic antibiotics, such with resistant and nonresistant strains of R. equi to see as the combination of a macrolide with rifampin (MaR), how foals might contaminate their environment with even though they would not have developed pneumonia. their excrement that can contain unabsorbed and me

For the study, the team screened 57 foals from 4 tabolized antibiotics. MaR tended to reduce the numfarms in central Kentucky for subclinical pneumonia, ber of bacteria in a plot's soil but increase the proporthen divided the foals into 3 equal groups. Two groups tion that were resistant. MeV ing ultrasounds found lesions on their lungs but the The research was funded by Morris Animal Foundation. farms with positive cases of R. equi pneumonia that For more information: 2 weeks. The third group served as a control group Alvarex-Narvaez S, Berghause LI, Morris ERA, et al. A common and was made up of similar aged, healthy foals, which practice of widespread antimicrobial use in horse production were monitored and not given any treatment. promotes multi-drug resistance. Scientific Reports. 2020 Jan 22

After 2 weeks, researchers analyzed fecal samples from each foal. DNA tests revealed that the MaR treated group had an increase in both the number and diversity of antibiotic-resistant genes in the bacteria. Most alarming was the discovery that the bacteria were resistant to multiple drugs and antibiotics. The GaM-treated and control groups showed no change in the number or diversity of resistance genes, a positive finding.

The team also experimentally infected soil plots with resistant and nonresistant strains of R. equi to see how foals might contaminate their environment with their excrement that can contain unabsorbed and metabolized antibiotics. MaR tended to reduce the number of bacteria in a plot's soil but increase the proportion that were resistant.

The research was funded by Morris Animal Foundation.

For more information:

Alvarex-Narvaez S, Berghause LI, Morris ERA, et al. A common practice of widespread antimicrobial use in horse production promotes multi-drug resistance. Scientific Reports. 2020 Jan 22 [epublished]. https://www.nature.com/articles/s41598-020-57479-9