Tylosin and lincomycin protect honey bee larvae from an oxytetracycline-resistant Melissococcus plutonius strain in vitro

Monday, November 14, 2022

11:54 AM – 12:06 PM PT

Location: Vancouver Convention Centre, Meeting Room 119/120

Presenting Author(s)

FM

Fatima Masood (she/her/hers)

MSc Candidate
University of Saskatchewan
Saskatoon, Saskatchewan, Canada

Co-Author(s)

Jenna thebeau

Graduate Student
University of Saskatchewan
Saskatoon, Saskatchewan, Canada
Ac

Allyssa cloet

University of Saskatchewan
Saskatoon, Saskatchewan, Canada
IK

Ivanna Kozii

University of Saskatchewan
Saskatoon, Saskatchewan, Canada
MZ

Michael Zabrodski

University of Saskatchewan
Saskatoon, Saskatchewan, Canada
Sarah Biganski

Postdoctoral Fellow
University of Saskatchewan
Saskatoon, Saskatchewan, Canada

Co-Author(s)

Marta Guarna

Research Scientist
Agriculture and Agri-Food Canada
Victoria, British Columbia, Canada

Co-Author(s)

ES

Elemir Simko

University of Saskatchewan
Saskatoon, Saskatchewan, Canada
ar

antonio ruzzini

University of Saskatchewan
Saskatoon, Saskatchewan, Canada
Sarah Wood

Research Chair in Pollinator Health and Associate Professor
University of Saskatchewan
Saskatoon, Saskatchewan, Canada

Melissococcus plutonius, a bacterial pathogen of honeybee larvae, is the causative agent of European foulbrood (EFB) disease. Western Canada has seen a recent emergence of EFB disease despite oxytetracycline (OTC) use, resulting in losses for beekeepers. Currently, the only approved treatment for EFB in Canada is OTC, an antibiotic that has been widely used in human/veterinary medicine since the late 1940s. In the context of other health systems, the emergence of antibiotic resistance to OTC and other tetracyclines is well-established. Additionally, OTC-resistance has been demonstrated in other honeybee pathogens, like Paenibacillus larvae, which causes American foulbrood disease. Thus, it is critical to understand the level and identity of resistance determinants associated with M. plutonius and find alternative treatments for EFB disease due to risk of OTC resistance. Indeed, we have discovered and phenotypically characterized the first known OTC-resistant strain: M. plutonius 2019BC1. The utility of OTC, lincomycin, and tylosin were compared through an experimental larval model. At varying concentrations, all three antibiotics prevented clinical signs of EFB disease following infection with M. plutonius 2019BC1 in vitro, though OTC was toxic to larvae at high doses. As we continue to investigate antimicrobial resistance (AMR) profiles of M. plutonius isolates from suspected EFB outbreaks, we expect a range of AMR phenotypes, reiterating the importance of expanding current therapeutic options along with alternative management practices to suppress EFB. Here, we demonstrated that tylosin and lincomycin, in cases of OTC-resistance, may be viable treatment options for M. plutonius infection in honeybee larvae.