title: Evaluation of the efficacy of intramuscular versus intramammary treatment of subclinical Streptococcus agalactiae mastitis in dairy cows in Colombia.
abstract: A randomized controlled trial was performed in 17 Colombian dairy herds to determine the cure risk among cows subclinically infected with Streptococcus agalactiae exposed to 2 antibiotic therapies. Composite milk samples were collected before milking at the onset of the trial (pretreatment) and 2 subsequent times over a period of approximately 63 d. The intramammary application (IMM) of ampicillin-cloxacillin was compared with the intramuscular application (IM) of penethamate hydriodide, and cure risks after an initial and retreatment application were assessed. Cure risk after the initial treatment was higher (82.4%) for the IMM treatment than for IM therapy (65.8%). However, no difference was observed in the cure risk of refractory cases after retreatment (IMM=52.6% vs. IM=51.2%). The cumulative cure risk (both initial and retreatment) was 90.4 and 82.9% for the IMM and IM products, respectively. A 2-level random effects logistic model that controlled for pretreatment cow-level somatic cell count, indicated that IM treatment (odds ratio=0.37) had a lower cure risk than IMM and a tendency for a lower cure risk with increasing baseline somatic cell count. Our findings suggest that both products and administration routes can reduce the prevalence of S. agalactiae in affected herds, but the IMM product had a better efficacy in curing the infection. In addition to the treatment protocol, the cow somatic cell count should be considered when making management decisions for cows infected with S. agalactiae.
authors.affiliation: Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island, C1A 4P3 Canada. Electronic address: jreyes@upei.ca.
authors.forename: J
authors.initials: J
authors.lastname: Reyes
authors.affiliation: Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island, C1A 4P3 Canada.
authors.forename: M
authors.initials: M
authors.lastname: Chaffer
authors.affiliation: Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island, C1A 4P3 Canada.
authors.forename: J
authors.initials: J
authors.lastname: Sanchez
authors.affiliation: Tropical Medicine Colombian Institute, CES University, CRA. 43A No. 52 sur-99 Medellín, Antioquia, Colombia.
authors.forename: G
authors.initials: G
authors.lastname: Torres
authors.affiliation: Cooperativa COLANTA, CRA 64C, 72-160 Medellín, Colombia.
authors.forename: D
authors.initials: D
authors.lastname: Macias
authors.affiliation: Cooperativa COLANTA, CRA 64C, 72-160 Medellín, Colombia.
authors.forename: M
authors.initials: M
authors.lastname: Jaramillo
authors.affiliation: Department of Agricultural and Livestock Sciences, Universidad de Caldas, Calle 65 #26-10, Manizales, Caldas, Colombia.
authors.forename: P C
authors.initials: PC
authors.lastname: Duque
authors.affiliation: Department of Agricultural and Livestock Sciences, Universidad de Caldas, Calle 65 #26-10, Manizales, Caldas, Colombia.
authors.forename: A
authors.initials: A
authors.lastname: Ceballos
authors.affiliation: Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island, C1A 4P3 Canada.
authors.forename: G P
authors.initials: GP
authors.lastname: Keefe
mesh_terms: D000667:Ampicillin / Q000008:administration & dosage; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D002417:Cattle; D002452:Cell Count / Q000662:veterinary; D003023:Cloxacillin / Q000008:administration & dosage; D003105:Colombia; D005260:Female; D007273:Injections, Intramuscular / Q000662:veterinary; D008414:Mastitis, Bovine / Q000188:drug therapy*; D010400:Penicillin G / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000627:therapeutic use; D013290:Streptococcal Infections / Q000188:drug therapy* / Q000662:veterinary; D013292:Streptococcus agalactiae / Q000187:drug effects / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents; C008780:penethamate hydroiodide; D000667:Ampicillin; D003023:Cloxacillin; D010400:Penicillin G
keywords: Streptococcus agalactiae; antibiotic; somatic cell count; subclinical mastitis