GRAM-NEGATIVES PROVE LETHAL IN EQUINE JOINT INFECTIONS B
New research shows that horses infected with sep-
tic joints linked to gram-negative bacteria, such as Enterobacteriaceae, are significantly more likely to die of the infection than are animals with other forms of microbes. The retrospective study found that gram-negative infections are less common—but significantly more deadly—than gram-positive infections, particularly when they exhibit resistance to current antimicrobial agents. 10
Issue 12/2018 | ModernEquineVet.com
But they also appear to be associated with telltale inflammatory indicators in affected joints—markers that could give equine veterinarians clues about refining therapy. Synovial infections are a significant source of morbidity and mortality for horses. An estimated 6–10% of affected animals will require euthanasia even after aggressive treatment. Even those that survive frequently suffer prolonged problems with their joints. “Septic synovial structures are true emergencies and should be referred if the logistics do not allow you to conduct aggressive and sustained therapy,” said Thomas P. Schaer, VMD, the director of the Preclinical Service Core and Orthopedic Surgery, Section of Surgery, at the University of Pennsylvania, School of Veterinary Medicine New Bolton Center, and a co-author of the study. “A favorable outcome is severely impaired if a patient does not get properly treated from the beginning. Appropriate choice and sustained antimicrobial chemotherapy are important components of a multipronged approach to treatment.” For the study, researchers at PennVet’s New Bolton Center in Kennett Square, Pa., looked at the medical records of 206 horses treated at PennVet for septic synovitis between 2010 and 2015. Affected joints by order of frequency included the tarsocrural joint (23.3%),
Photo courtesy of Dr. Thomas Schaer
Three different pathogenic bacteria photographed using different imaging techniques. First column depicts macroscopic images of bacterial aggregates in synovial fluid of horses. The middle column shows the same bacterial cluster using confocal microscopy, which allows the study of various material components making up the cluster. The third column shows scanning electron microscopy of the same bacterial cluster allowing the study of 3 dimensional arrangement of clusters including the bacteria proper (arrows).
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