Reference | Juntunen2013 (10011)

Aims: To determine whether therapeutic treatment of pigs with chlortetracycline affects the susceptibility of their Campylobacter isolates for tetracycline, ciprofloxacin and erythromycin. We selected two finishing herds in which pigs were therapeutically treated with chlortetracycline, and we determined minimum inhibitory concentrations (MICs) for Camp. Coli isolates before, during and after treatment. Faecal samples were collected from ear-tagged finishing pigs (age 3–5 months) suffering from respiratory tract infections in two Finnish herds (herd 1: 420 finishers; herd 2: 1575 finishers). All pigs from herd 1 were medicated, and 33 pigs were sampled at three time points. All of herd 2, except for the pigs from two pens, received chlortetracycline treatment; 20 treated and 20 untreated pigs were sampled at three time points. Local veterinarians prescribed oral chlortetracycline, which was mixed in feed (35 mg of chlortetracycline per kg of body weight) for a 10-day period. The first samples were collected on the day before the start of the antimicrobial medication. The second set of samples was taken on the 6th or 7th day of chlortetracycline therapy, and the third set was completed 22–24 days after cessation of the medication (33 and 35 days after the first sampling). The antimicrobial susceptibility of Campylobacter isolates to ciprofloxacin, erythromycin and tetracycline was determined by the broth microdilution method (CLSI 2008). Tetracycline MICs for 63 Camp. coli isolates from the samples collected between 2007 and 2009 were determined by broth microdilution method (described above) or by the VetMIC method. Antimicrobial resistance was classified as microbiological resistance according to the epidemiological cut-off values (ECOFFs) published by the European Committee on Antimicrobial Susceptibility Testing.

Individual faecal samples were taken from the rectum with Probact transport swabs ( Juntunen et al., 2010).

AST Method: Broth Microdilution

Reference explicitly reports AST breakpoints: True

Reference reports using a MIC table: True