Identification of Mammaliicoccus fleurettii as the source of a methicillin-resistance gene in a First Nation reserve lake in Manitoba, Canada

Our study aimed to identify the bacterial source of a previously detected mobile antibiotic-resistance gene, mecA, found in a lake that serves as a source to a water treatment plant operated by a First Nation reserve. Three methicillin-resistant presumptive Staphylococcus spp. isolated from the sample using selective media were verified as mecA positive by PCR (polymerase chain reaction). MALDI-TOF (matrix-assisted laser desorption ionization–time-of-flight mass spectrometry) and whole genome sequencing of each isolate confirmed that all three were Mammaliicoccus fleurettii. Antibiotic-resistance gene analysis of the assembled genomes predicted mecA with 99.7% sequence identity, and phylogenetic analysis grouped our three mecA genes with the mecA allele from a methicillin-resistant strain of Staphylococcus aureus. Identifying microbial species known to harbour mobile antibiotic-resistance elements can provide greater depth of information about drinking water, an especially essential need in First Nation reserves where water quality too frequently is poor.