title: In vitro activity of tylvalosin against Spanish field strains of Mycoplasma hyopneumoniae.
abstract: Mycoplasma hyopneumoniae is involved in the porcine enzootic pneumonia and respiratory disease complex; therefore, the search for new treatment options that contribute to the control of this organism is relevant. The minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations of tylvalosin and 19 other antimicrobial agents against 20 Spanish field isolates of M. hyopneumoniae were determined using the broth microdilution method, with the type strain (J) as a control strain. Tylvalosin had MIC50 and MIC90 values of 0.016 and 0.06 µg/ml, respectively, and was the second-most effective of the assayed antibiotics, after valnemulin. Tiamulin, tylosin and lincomycin were also among the antibiotics with the lowest MIC50 and MIC90 values against the 20 field isolates (0.06-0.25 µg/ml). However, resistance to tylosin and spiramycin, which like tylvalosin, are 16-membered macrolides, was observed. The MIC50 and MIC90 values for ciprofloxacin and enrofloxacin ranged from 0.125 to 1 µg/ml; the corresponding values ranged from 2 to 4 µg/ml for oxytetracyline, which was the most active tetracycline. Furthermore, tylvalosin and valnemulin exhibited the highest bactericidal activities. In conclusion, the macrolide tylvalosin and the pleuromutilin valnemulin exhibited the highest in vitro antimicrobial activities against M. hyopneumoniae field isolates in comparison with the other tested antibiotics.
authors.affiliation: Unidad de Epidemiología y Medicina Preventiva, Instituto Universitario de Sanidad Animal (IUSA), Universidad de Las Palmas de Gran Canaria, Arucas, Spain Microbiología, Departamento de Ciencias Clínicas, Facultad de Ciencias de la Salud, Universidad de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.
authors.forename: M M
authors.initials: MM
authors.lastname: Tavío
authors.affiliation: Unidad de Epidemiología y Medicina Preventiva, Instituto Universitario de Sanidad Animal (IUSA), Universidad de Las Palmas de Gran Canaria, Arucas, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Poveda
authors.affiliation: Unidad de Epidemiología y Medicina Preventiva, Instituto Universitario de Sanidad Animal (IUSA), Universidad de Las Palmas de Gran Canaria, Arucas, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Assunção
authors.affiliation: Unidad de Epidemiología y Medicina Preventiva, Instituto Universitario de Sanidad Animal (IUSA), Universidad de Las Palmas de Gran Canaria, Arucas, Spain.
authors.forename: A S
authors.initials: AS
authors.lastname: Ramírez
authors.affiliation: Unidad de Epidemiología y Medicina Preventiva, Instituto Universitario de Sanidad Animal (IUSA), Universidad de Las Palmas de Gran Canaria, Arucas, Spain.
authors.forename: J B
authors.initials: JB
authors.lastname: Poveda
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology*; D058491:Bacterial Load / Q000662:veterinary; D066298:In Vitro Techniques / Q000662:veterinary; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D045705:Mycoplasma hyopneumoniae / Q000145:classification* / Q000187:drug effects* / Q000302:isolation & purification; D013030:Spain; D013552:Swine; D013553:Swine Diseases / Q000188:drug therapy / Q000382:microbiology; D015645:Tylosin / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D000890:Anti-Infective Agents; C545430:tylvalosin; D015645:Tylosin
keywords: Antimicrobials; Bacterial diseases; Chemotherapy; Mycoplasmas; Pigs; Pneumonia