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Infectious Disease | 206 Publications
Ursea R, De Castro D, Bowen T, Chan CC. The role of conjunctival biopsy in the diagnosis of granulomatosis with polyangiitis.. J Ophthalmic Inflamm Infect. 2015;5(1):1.

BACKGROUND: The purpose of this study is to describe a patient who was diagnosed with granulomatosis with polyangiitis based on conjunctival biopsy. This study is a case report and review of the literature. FINDINGS: A 48-year-old Caucasian woman presented with a 2-week history of a left eye peripheral corneal ulcer with adjacent conjunctivitis and a 4-month history of a non-resolving productive cough. Given her elevated serum perinuclear antineutrophil cytoplasmic antibody (P-ANCA) and erythrocyte sedimentation rate (ESR) levels as well as a chest computed topography (CT) that showed bilateral patchy infiltrates, suspicion of limited granulomatosis with polyangiitis with lung and ocular involvement was high. Because bronchoalveolar lavage was nondiagnostic for granulomatous disease, conjunctival biopsy was initially attempted in order to avoid a more invasive lung biopsy. The conjunctival biopsy revealed mixed subacute inflammatory mediators and vasculitis consistent with granulomatosis with polyangiitis. CONCLUSIONS: Conjunctival biopsy may be a valuable, minimally invasive method for diagnosing systemic granulomatosis with polyangiitis.

Mukherjee S, Zhou X, Rajaiya J, Chodosh J. Ultrastructure of adenovirus keratitis.. Invest Ophthalmol Vis Sci. 2015;56(1):472–7.

PURPOSE: We determined the ultrastructure of mouse adenovirus keratitis, a model for human adenovirus keratitis. METHODS: Adenovirus keratitis was induced in C57Bl/6j mice by intrastromal injection of human adenovirus species D type 37 (HAdV-D37) with a heat-pulled, glass, micropipette needle under compressed air. At select time points after infection, mice were euthanized and their corneas removed, fixed, and sectioned at 70-nm thickness for electron microscopy. RESULTS: Injection of HAdV-D37 into the mouse corneal stroma placed virus predominantly in the pericellular corneal stromal matrix. Virus was seen bound to and entering stromal cells at 1 and 2 hours after infection, respectively. Cell membrane transit by virus was seen to involve two distinct structures resembling caveolae and macropinosomes. However, later during infection intracellular virus was not seen within membrane-bound organelles. By 8 hours after infection, intracellular virus had accumulated into densely packed, perinuclear arrays. Virus disassembly was not obvious at any time point after infection. Infiltrating neutrophils seen by one day after infection had engulfed degraded stromal cells by 4 days after infection. CONCLUSIONS: By transmission electron microscopy, injected HAdV-D37 readily enters stromal cells in the C57Bl/6j mouse cornea and induces stromal inflammation, as was shown previously by light microscopy. However, electron microscopy also revealed dense, static arrays of intracytoplasmic virus, suggesting a block in viral capsid disassembly and viral DNA nuclear entry. These findings may explain why human adenoviruses do not replicate in the mouse corneal stroma.

Santa Maria J, Sadaka A, Moussa S, Brown S, Zhang Y, Rubin E, Gilmore M, Walker S. Compound-gene interaction mapping reveals distinct roles for Staphylococcus aureus teichoic acids. Proc Natl Acad Sci U S A. 2014;111(34):12510–5.
Staphylococcus aureus contains two distinct teichoic acid (TA) polymers, lipoteichoic acid (LTA) and wall teichoic acid (WTA), which are proposed to play redundant roles in regulating cell division. To gain insight into the underlying biology of S. aureus TAs, we used a small molecule inhibitor to screen a highly saturated transposon library for cellular factors that become essential when WTA is depleted. We constructed an interaction network connecting WTAs with genes involved in LTA synthesis, peptidoglycan synthesis, surface protein display, and D-alanine cell envelope modifications. Although LTAs and WTAs are synthetically lethal, we report that they do not have the same synthetic interactions with other cell envelope genes. For example, D-alanylation, a tailoring modification of both WTAs and LTAs, becomes essential when the former, but not the latter, are removed. Therefore, D-alanine-tailored LTAs are required for survival when WTAs are absent. Examination of terminal phenotoypes led to the unexpected discovery that cells lacking both LTAs and WTAs lose their ability to form Z rings and can no longer divide. We have concluded that the presence of either LTAs or WTAs on the cell surface is required for initiation of S. aureus cell division, but these polymers act as part of distinct cellular networks.
Sadaka A, Palmer K, Suzuki T, Gilmore M. In vitro and in vivo models of Staphylococcus aureus endophthalmitis implicate specific nutrients in ocular infection. PLoS One. 2014;9(10):e110872.
PURPOSE: To define global transcriptional responses of Staphylococcus aureus and its codY mutant (CodY is a transcription regulator of virulence and metabolic genes in response to branched-chain amino acids) when growing in bovine aqueous (AH) and vitreous humor (VH) in vitro, and to investigate the impact of codY deletion on S. aureus virulence in a novel murine anterior chamber (AC) infection model. METHODS: For the in vitro model, differential transcriptomic gene expression of S. aureus and its codY mutant grown in chemically defined medium (CDM), AH, and VH was analyzed. Furthermore, the strains were inoculated into the AC of mice. Changes in bacterial growth, electroretinography and inflammation scores were monitored. RESULTS: Bovine AH and VH provide sufficient nutrition for S. aureus growth in vitro. Transcriptome analysis identified 72 unique open reading frames differentially regulated ≥10-fold between CDM, AH, and VH. In the AC model, we found comparable growth of the codY mutant and wild type strains in vivo. Average inflammation scores and retinal function were significantly worse for codY mutant-infected eyes at 24 h post-infection. CONCLUSION: Our in vitro bovine AH and VH models identified likely nutrient sources for S. aureus in the ocular milieu. The in vivo model suggests that control of branched-chain amino acid availability has therapeutic potential in limiting S. aureus endophthalmitis severity.
Van Tyne D, Gilmore M. A delicate balance: maintaining mutualism to prevent disease.. Cell Host Microbe. 2014;16(4):425–7.

The intestinal microbial ecosystem is complex, and few of the principles that contribute to homeostasis in health are well understood. Pham et al. (2014) show that a network including the epithelial interleukin-22 receptor protects against infection with the opportunistic pathogen Enterococcus faecalis through promotion of host-microbiota mutualism.

Van Tyne D, Gilmore M. Friend turned foe: evolution of enterococcal virulence and antibiotic resistance. Annu Rev Microbiol. 2014;68:337–56.
The enterococci are an ancient genus that evolved along with the tree of life. These intrinsically rugged bacteria are highly adapted members of the intestinal consortia of a range of hosts that spans the animal kingdom. Enterococci are also leading opportunistic hospital pathogens, causing infections that are often resistant to treatment with most antibiotics. Despite the importance of enterococci as hospital pathogens, the vast majority live outside of humans, and nearly all of their evolutionary history took place before the appearance of modern humans. Because hospital infections represent evolutionary end points, traits that exacerbate human infection are unlikely to have evolved for that purpose. However, clusters of traits have converged in specific lineages that are well adapted to colonize the antibiotic-perturbed gastrointestinal tracts of patients and that thrive in the hospital environment. Here we discuss these traits in an evolutionary context, as well as how comparative genomics is providing new insights into the evolution of the enterococci.