title: Susceptibility of Mycobacterium avium sbsp paratuberculosis to monensin sodium or tilmicosin phosphate in vitro and resulting infectivity in a murine model.
abstract: This study was designed to determine the susceptibility in vitro and infectivity of 1 field isolate of Mycobacterium avium sbsp paratuberculosis after exposure to monensin sodium and tilmicosin phosphate. Minimum inhibitory concentrations (0.39 microg monensin sodium/mL; 1.60 microg tilmicosin phosphate/mL) were determined in quintuplicate. Organisms were then incubated with 3 different concentrations of each medication for 3 different lengths of time, then washed and resuspended in sterile physiologic saline and injected intraperitoneally into mice that were genetically susceptible to infection. Mice were euthanatized 50 d later and the number of hepatic granulomas was used as the indicator of infectivity. Neither time of incubation nor concentration of medication had any effect on the infectivity of the organisms. Monensin sodium significantly reduced the number of hepatic granulomas in genetically susceptible mice while tilmicosin phosphate did not. Antimycobacterial activity of monensin sodium suggests that the role of monensin in the control of bovine paratuberculosis should be evaluated further.
authors.affiliation: Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine, Texas A&M University, College Station, Texas, USA. gbrumbaugh@cvm.tamu.edu
authors.forename: Gordon W
authors.initials: GW
authors.lastname: Brumbaugh
authors.forename: R Bruce
authors.initials: RB
authors.lastname: Simpson
authors.forename: John F
authors.initials: JF
authors.lastname: Edwards
authors.forename: Dwayne R
authors.initials: DR
authors.lastname: Anders
authors.forename: T D
authors.initials: TD
authors.lastname: Thomson
mesh_terms: D000818:Animals; D000995:Antitubercular Agents / Q000494:pharmacology* / Q000627:therapeutic use; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy / Q000382:microbiology; D004195:Disease Models, Animal; D024881:Drug Resistance, Bacterial; D005260:Female; D018942:Macrolides / Q000494:pharmacology* / Q000627:therapeutic use; D051379:Mice; D008810:Mice, Inbred C57BL; D008826:Microbial Sensitivity Tests; D008985:Monensin / Q000494:pharmacology* / Q000627:therapeutic use; D016927:Mycobacterium avium subsp. paratuberculosis / Q000187:drug effects* / Q000472:pathogenicity; D010283:Paratuberculosis / Q000188:drug therapy / Q000382:microbiology; D015645:Tylosin / Q000031:analogs & derivatives* / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: D000995:Antitubercular Agents; D018942:Macrolides; D008985:Monensin; C052319:tilmicosin; D015645:Tylosin