Molecular characterization of Clostridium difficile isolates from horses in an intensive care unit and association of disease severity with strain type.
OBJECTIVE
To determine molecular characteristics, antimicrobial susceptibility, and toxigenicity of Clostridium difficile isolates from horses in an intensive care unit and evaluate associations among severity of clinical disease with specific strains of C difficile.


METHODS
Prospective study.


METHODS
130 horses.


METHODS
Feces were collected from horses admitted for acute gastrointestinal tract disease with loose feces and submitted for microbial culture and immunoassay for toxin production. Polymerase chain reaction assays were performed on isolates for toxins A and B genes and strain identification.


RESULTS
Isolates were grouped into 3 strains (A, B, and C) on the basis of molecular banding patterns. Toxins A and B gene sequences were detected in 93%, 95%, and 73% of isolates of strains A, B, and C, respectively. Results of fecal immunoassays for toxin A were positive in 40%, 63%, and 16% of horses with strains A, B, and C, respectively. Isolates in strain B were resistant to metronidazole. Horses infected with strain B were 10 times as likely to have been treated with metronidazole prior to the onset of diarrhea as horses infected with other strains. Duration from onset of diarrhea to discharge (among survivors) was longer, systemic inflammatory response syndromes were more pronounced, and mortality rate was higher in horses infected with strain B than those infected with strains A and C combined.


CONCLUSIONS
Horses may be infected with a number of heterogeneous isolates of C difficile. Results indicated that toxigenicity and antimicrobial susceptibility of isolates vary and that metronidazole-resistant strains may be associated with severe disease.
Magdesian
K Gary
KG
Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
Dujowich
Mauricio
M
Madigan
John E
JE
Hansen
Lori M
LM
Hirsh
Dwight C
DC
Jang
Spencer S
SS
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use*; D001427:Bacterial Toxins / Q000032:analysis* / Q000737:chemistry; D001483:Base Sequence; D016360:Clostridioides difficile / Q000145:classification / Q000187:drug effects / Q000302:isolation & purification; D024881:Drug Resistance, Bacterial; D004761:Enterocolitis, Pseudomembranous / Q000188:drug therapy / Q000382:microbiology*; D005243:Feces / Q000382:microbiology; D005260:Female; D006734:Horse Diseases / Q000188:drug therapy / Q000382:microbiology*; D006736:Horses; D006762:Hospitals, Animal; D008297:Male; D008795:Metronidazole / Q000494:pharmacology / Q000627:therapeutic use; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000379:methods / Q000662:veterinary; D011446:Prospective Studies; D012720:Severity of Illness Index
D000900:Anti-Bacterial Agents; D001427:Bacterial Toxins; D008795:Metronidazole