Rhizobium Radiobacter Infection in a 27-Year-Old African American Woman With Munchausen Syndrome

Flagellotropic Bacteriophages: Opportunities and Challenges for Antimicrobial Applications

Bacteriophages (phages) are the most abundant biological entities in the biosphere. As viruses that solely infect bacteria, phages have myriad healthcare and agricultural applications including phage therapy and antibacterial treatments in the foodservice industry. Phage therapy has been explored since the turn of the twentieth century but was no longer prioritized following the invention of antibiotics. As we approach a post-antibiotic society, phage therapy research has experienced a significant resurgence for the use of phages against antibiotic-resistant bacteria, a growing concern in modern medicine. Phages are extraordinarily diverse, as are their host receptor targets. Flagellotropic (flagellum-dependent) phages begin their infection cycle by attaching to the flagellum of their motile host, although the later stages of the infection process of most of these phages remain elusive. Flagella are helical appendages required for swimming and swarming motility and are also of great importance for virulence in many pathogenic bacteria of clinical relevance. Not only is bacterial motility itself frequently important for virulence, as it allows pathogenic bacteria to move toward their host and find nutrients more effectively, but flagella can also serve additional functions including mediating bacterial adhesion to surfaces. Flagella are also a potent antigen recognized by the human immune system. Phages utilizing the flagellum for infections are of particular interest due to the unique evolutionary tradeoff they force upon their hosts: by downregulating or abolishing motility to escape infection by a flagellotropic phage, a pathogenic bacterium would also likely attenuate its virulence. This factor may lead to flagellotropic phages becoming especially potent antibacterial agents. This review outlines past, present, and future research of flagellotropic phages, including their molecular mechanisms of infection and potential future applications.

Case of isolated Rhizobium radiobacter contact lens-related infectious keratitis: A plant microbe now emerging as a human pathogen

Purpose

To report a case of contact lens-related infectious keratitis caused by the Gram-negative plant pathogen Rhizobium radiobacter.

Observations

A 26-year old lady with history of contact lens use presented with three weeks history of right eye redness and pain, with the left eye also being involved in the past week. Slit lamp examination of the right eye demonstrated multiple faint subepithelial and stromal infiltrates with no overlying epithelial defect, and no anterior chamber activity. Anterior segment optical coherence tomography demonstrated multiple hyper-reflective foci scattered at various depths of the corneal stroma. Corneal scrapings grew Rhizobium radiobacter, and culture-directed antibiotic therapy with topical gentamicin and levofloxacin resulted in slow clinical improvement of the R. radiobacter keratitis without visual sequelae.

Conclusions and importance

We have described the clinical features, microbial susceptibilities, and response to treatment in a case of R. radiobacter infectious keratitis.

R. radiobacter has recently emerged as a source for several ocular and systemic infections and was identified in a series of polymicrobial keratitis cases. Our case report of monomicrobial R. radiobacter keratitis adds to the sparse literature on this uncommon but potentially sight-threatening infection.