Comparative Genomics and Antimicrobial Resistance Profiling of Elizabethkingia Isolates Reveal Nosocomial Transmission and In Vitro Susceptibility to Fluoroquinolones, Tetracyclines, and Trimethoprim-Sulfamethoxazole

The Elizabethkingia genus has gained global attention in recent years as a sporadic, worldwide, nosocomial pathogen. Elizabethkingia spp. are intrinsically multidrug resistant, primarily infect immunocompromised individuals, and are associated with high mortality (∼20-40%). Yet, gaps remain in our understanding of transmission, global strain relatedness, antimicrobial resistance and effective therapy. Over a 16-year period 22 clinical and six hospital environmental isolates were collected from Queensland, Australia. Identification using the MALDI-TOF MS (VITEK® MS) and whole-genome sequencing was compared with a global strain dataset. Phylogenomic reconstruction robustly identified 22 E. anophelis, three E. miricola, two E. meningoseptica and one E. bruuniana, most of which branched as unique lineages. Global analysisrevealed some Australian E. anophelis isolates are genetically closely related to strains identified from the USA, England and Asia. Comparative genomics of clinical and environmental strains identified evidence of nosocomial transmission in patients, indicating probable infection from a hospital reservoir. Furthermore, broth microdilution against 39 antimicrobials revealed almost ubiquitous resistance to aminoglycosides, carbapenems, cephalosporins and penicillins. Like other international strains, our isolates expressed susceptibility to minocycline and levofloxacin and the less common trimethoprim/sulfamethoxazole. Our study demonstrates important new insights into the genetic diversity, environmental persistence, transmission of and potential effective therapy for Australian Elizabethkingia species.