RESUMO
BACKGROUND: Despite their indispensability in human medicine, fluoroquinolones (FQ) are used for the treatment of bacterial infections in farm animals which increases the risk of transferring FQ-resistant bacteria into the environment and via the food chain to humans. The objectives of this observational study were to follow-up of the presence of quinolone non-susceptible Escherichia coli (QNSE) qualitatively and quantitatively in faecal samples of pigs at four time points (2 weeks old, 4 weeks old, 2 weeks post weaning and during fattening period). Moreover differences between groups of FQ-treated pigs, pigs with contact to treated pigs and control pigs were investigated. Additionally, quinolone and FQ resistance of Escherichia coli isolates of the faecal samples were investigated by determining minimum inhibitory concentrations (MICs). RESULTS: 40.9% of 621 fecal samples contained QNSE. Proportion of samples with detectable QNSE from treated and contact pigs did not differ significantly and were highest in piglets of 2 and 4 weeks of age. However, the proportions of samples with QNSE were significantly lowest in control pigs (7/90; 7.8%; CI = 3.5-14.7%) among all groups. Also, the number of colony-forming units was lowest in both weaners and fattening pigs of the control group compared to treated and contact groups. Following CLSI human breakpoints, in total, 50.4% out of 254 isolates in faecal samples were intermediate or resistant to ciprofloxacin. CONCLUSIONS: QNSE were present in faeces of pigs independent of age or FQ background but significantly less were found in pigs from farms without FQ usage. Due to the long half-life of FQ, it is likely that only a prolonged absence of fluoroquinolone treatments in pig farming will lead to a reduced frequency of QNSE in the farm environment. Solutions need to be found to minimise the emergence and transfer of quinolone and FQ-resistant bacteria from treated pigs to contact pigs and to farms without FQ usage.
RESUMO
OBJECTIVES: The optimal dosage regimen of gentamicin in horses is still under investigation. The objectives of this study were to determine gentamicin plasma concentrations in hospitalized horses treated with 10 mg/kg gentamicin (IV, q 24 h) and to determine whether a plasma concentration to minimum inhibitory concentration (MIC) ratio of 10:1 is reached for equine pathogens using this dose. DESIGN: Prospective clinical observational study; retrospective study on MICs of 131 gram-negative bacteria isolated from horses (2012-2015). SETTING: University teaching hospital. ANIMALS: Ninety-eight horses >6 months old, treated with gentamicin for their primary disease, consecutive samples. MEASUREMENTS AND MAIN RESULTS: Plasma concentrations were measured 1 hour (C1h ) and 20 hours (C20h ) after gentamicin administration using fluorescence polarization. Presence of systemic inflammatory response syndrome (SIRS) and azotemia was recorded, as well as the reason for antimicrobial administration (primary disease) and whether administration was prophylactic or therapeutic. The target C1h of ≥20 µg/mL gentamicin was reached in 90% of horses and was sufficient to reach a plasma concentration:MIC of 10:1 in 32 of 131 (24%) of gram-negative aerobic bacteria. A C20h ≤ 2 µg/mL was reached in 97% horses. Therapeutic versus prophylactic administration, primary disease, azotemia, and systemic inflammatory response syndrome were not associated with a failure to reach a desired peak or trough. CONCLUSIONS: The gentamicin dose of 10 mg/kg every 24 hours should be further investigated and safety assessed because a target gentamicin plasma concentration of ≥20 µg/mL was achieved in the majority of cases. Nephrotoxic side effects were not assessed. Individual drug monitoring should be performed because clinical factors are unreliable predictors of plasma concentrations. A gentamicin target concentration of ≥40 µg/mL does not offer additional benefits compared to ≥20 µg/mL, due to the bimodal distribution of resistance in bacterial isolates.
