Fluoroquinolones (FQs) and ciprofloxacin (Cp) are important antimicrobials that pollute the environment in trace amounts. Although Cp has been recommended as prophylaxis for patients undergoing leech therapy to prevent infections by the leech gut symbiont Aeromonas, a puzzling rise in Cp-resistant (Cpr) Aeromonas infections has been reported. We report on the effects of subtherapeutic FQ concentrations on bacteria in an environmental reservoir, the medicinal leech, and describe the presence of multiple antibiotic resistance mutations and a gain-of-function resistance gene. We link the rise of CprAeromonas isolates to exposure of the leech microbiota to very low levels of Cp (0.01 to 0.04 µg/ml), <1/100 of the clinical resistance breakpoint for aeromonas using competition experiments and comparative genomics 37 strains, we determined mechanisms in leech-derived isolates, traced their origin, that presence merely 0.01 µg/ml cp provides a strong competitive advantage cpr strains. deep-sequencing cpr-conferring region gyra enabled tracing mutation-harboring population archived gut samples, an increase frequency mutation 2011 coincides with initial reports cpraeromonas infections patients receiving leech therapy.importance role subtherapeutic antimicrobial contamination selecting resistant strains has received increasing attention is important matter. this study describes relationship bacteria from medicinal leech, hirudo verbana, patient following therapy. while our results highlight need alternative antibiotic therapies, rise demonstrates importance restricting exposure animals to antibiotics approved veterinary use. shift more community dispersion via mobile elements occurred natural setting due very low levels fluoroquinolones, revealing challenges controlling spread antibiotic-resistant highlighting holistic approach management copyright © 2018 beka et al.
Journal: mBio
DOI: 10.1128/mBio.01328-18
Year: 2018