Molecular epidemiology of Salmonella Heidelberg in an equine hospital.
From 1992 to 1997, multi-drug resistant (MDR) Salmonella Heidelberg isolates were cultured from a number of horses hospitalised in a veterinary hospital in Victoria, Australia. To examine the relationships between the cases, 28 isolates from the hospital were compared by pulsed field gel electrophoresis (PFGE), IS200 element profiles, antimicrobial resistance patterns, plasmid profiles and phage typing. The PFGE patterns following digestion with XbaI and BlnI restriction endonucleases showed that the isolates from the veterinary hospital originated from a common source. These isolates also had indistinguishable IS200 profiles. However, PFGE was more discriminatory than IS200 profiles. All the veterinary hospital isolates and one independent isolate had the same antimicrobial resistance pattern and had at least one plasmid in common. Localisation of antimicrobial resistance genes indicated that the veterinary hospital isolates had more than one plasmid carrying resistance genes and that the genes encoding sulphathiazole and trimethoprim resistance were not on these plasmids. Phage typing was ineffective as 22 of the 28 isolates were untypeable. In conclusion, the combination of different methods used for epidemiological studies suggested that a single strain of MDR S. Heidelberg was isolated from horses admitted to the hospital for 6 years and caused salmonellosis in susceptible horses within that period with no apparent correlation between the antimicrobials used and retention of its MDR phenotype.
School of Veterinary Science, The University of Melbourne, Vic. 3010, Parkville, Australia.
P
P
Amavisit
P F
PF
Markham
D
D
Lightfoot
K G
KG
Whithear
G F
GF
Browning
D000818:Animals; D001315:Australia / Q000453:epidemiology; D015252:Deoxyribonucleases, Type II Site-Specific / Q000378:metabolism; D004352:Drug Resistance, Microbial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field / Q000662:veterinary; D005838:Genotype; D006734:Horse Diseases / Q000453:epidemiology / Q000382:microbiology*; D006736:Horses; D006762:Hospitals, Animal; D017720:Molecular Epidemiology; D010641:Phenotype; D012475:Salmonella / Q000145:classification* / Q000235:genetics; D012481:Salmonella Infections, Animal / Q000453:epidemiology* / Q000382:microbiology
C025580:endodeoxyribonuclease XBAI; C064053:CCTAGG-specific type II deoxyribonucleases; D015252:Deoxyribonucleases, Type II Site-Specific