Infectious Disease

Jonas RA, Ung L, Rajaiya J, Chodosh J. Mystery Eye: Human Adenovirus and the Enigma of Epidemic Keratoconjunctivitis. Prog Retin Eye Res 2019;:100826.Abstract
Known to occur in widespread outbreaks, epidemic keratoconjunctivitis (EKC) is a severe ocular surface infection with a strong historical association with human adenovirus (HAdV). While the conjunctival manifestations can vary from mild follicular conjunctivitis to hyper-acute, exudative conjunctivitis with formation of conjunctival membranes, EKC is distinct as the only form of adenovirus conjunctivitis in which the cornea is also involved, likely due to specific corneal epithelial tropism of its causative viral agents. The initial development of a punctate or geographic epithelial keratitis may herald the later formation of stromal keratitis, and manifest as subepithelial infiltrates which often persist or recur for months to years after the acute infection has resolved. The chronic keratitis in EKC is associated with foreign body sensation, photophobia, glare, and reduced vision. However, over a century since the first clinical descriptions of EKC, and over 60 years since the first causative agent, human adenovirus type 8, was identified, our understanding of this disorder remains limited. This is underscored by a current lack of effective diagnostic tools and treatments. In part, stasis in our knowledge base has been encouraged by the continued acceptance, and indeed propagation of, inaccurate paradigms pertaining to disease etiology and pathogenesis, particularly with regard to mechanisms of innate and adaptive immunity within the cornea. Owing to its often persistent and medically refractory visual sequelae, reconsideration of key aspects of EKC disease biology is warranted to identify new treatment targets to curb its worldwide socioeconomic burden.
Ung L, Acharya NR, Agarwal T, Alfonso EC, Bagga B, Bispo PJM, Burton MJ, Dart JK, Doan T, Fleiszig SM, Garg P, Gilmore MS, Gritz DC, Hazlett LD, Iovieno A, Jhanji V, Kempen JH, Lee CS, Lietman TM, Margolis TP, McLeod SD, Mehta JS, Miller D, Pearlman E, Prajna L, Prajna VN, Seitzman GD, Shanbhag SS, Sharma N, Sharma S, Srinivasan M, Stapleton F, Tan DT, Tandon R, Taylor HR, Tu EY, Tuli SS, Vajpayee RB, Van Gelder RN, Watson SL, Zegans ME, Chodosh J. Infectious corneal ulceration: a proposal for neglected tropical disease status. Bull World Health Organ 2019;97(12):854-856.
Ung L, Bispo PJM, Bryan NC, Andre C, Chodosh J, Gilmore MS. The Best of All Worlds: Conjunctivitis through the Lens of Community Ecology and Microbial Biogeography. Microorganisms 2019;8(1)Abstract
The study of the forces which govern the geographical distributions of life is known as biogeography, a subject which has fascinated zoologists, botanists and ecologists for centuries. Advances in our understanding of community ecology and biogeography-supported by rapid improvements in next generation sequencing technology-have now made it possible to identify and explain where and why life exists as it does, including within the microbial world. In this review, we highlight how a unified model of microbial biogeography, one which incorporates the classic ecological principles of selection, diversification, dispersion and ecological drift, can be used to explain community dynamics in the settings of both health and disease. These concepts operate on a multiplicity of temporal and spatial scales, and together form a powerful lens through which to study microbial population structures even at the finest anatomical resolutions. When applied specifically to curious strains of conjunctivitis-causing, nonencapsulated , we show how this conceptual framework can be used to explain the possible evolutionary and disease-causing mechanisms which allowed these lineages to colonize and invade a separate biogeography. An intimate knowledge of this radical bifurcation in phylogeny, still the only known niche subspecialization for to date, is critical to understanding the pathogenesis of ocular surface infections, nature of host-pathogen interactions, and developing strategies to curb disease transmission.
Manson AL, Van Tyne D, Straub TJ, Clock S, Crupain M, Rangan U, Gilmore MS, Earl AM. Chicken Meat-Associated Enterococci: Influence of Agricultural Antibiotic Use and Connection to the Clinic. Appl Environ Microbiol 2019;85(22)Abstract
Industrial farms are unique, human-created ecosystems that provide the perfect setting for the development and dissemination of antibiotic resistance. Agricultural antibiotic use amplifies naturally occurring resistance mechanisms from soil ecologies, promoting their spread and sharing with other bacteria, including those poised to become endemic within hospital environments. To better understand the role of enterococci in the movement of antibiotic resistance from farm to table to clinic, we characterized over 300 isolates of cultured from raw chicken meat purchased at U.S. supermarkets by the Consumers Union in 2013. and were the predominant species found, and antimicrobial susceptibility testing uncovered striking levels of resistance to medically important antibiotic classes, particularly from classes approved by the FDA for use in animal production. While nearly all isolates were resistant to at least one drug, bacteria from meat labeled as raised without antibiotics had fewer resistances, particularly for Whole-genome sequencing of 92 isolates revealed that both commensal- and clinical-isolate-like enterococcal strains were associated with chicken meat, including isolates bearing important resistance-conferring elements and virulence factors. The ability of enterococci to persist in the food system positions them as vehicles to move resistance genes from the industrial farm ecosystem into more human-proximal ecologies. Bacteria that contaminate food can serve as a conduit for moving drug resistance genes from farm to table to clinic. Our results show that chicken meat-associated isolates of are often multidrug resistant, closely related to pathogenic lineages, and harbor worrisome virulence factors. These drug-resistant agricultural isolates could thus represent important stepping stones in the evolution of enterococci into drug-resistant human pathogens. Although significant efforts have been made over the past few years to reduce the agricultural use of antibiotics, continued assessment of agricultural practices, including the roles of processing plants, shared breeding flocks, and probiotics as sources for resistance spread, is needed in order to slow the evolution of antibiotic resistance. Because antibiotic resistance is a global problem, global policies are needed to address this threat. Additional measures must be taken to mitigate the development and spread of antibiotic resistance elements from farms to clinics throughout the world.
Gaca AO, Lemos JA. Adaptation to Adversity: the Intermingling of Stress Tolerance and Pathogenesis in Enterococci. Microbiol Mol Biol Rev 2019;83(3)Abstract
SUMMARY is a diverse and rugged genus colonizing the gastrointestinal tract of humans and numerous hosts across the animal kingdom. Enterococci are also a leading cause of multidrug-resistant hospital-acquired infections. In each of these settings, enterococci must contend with changing biophysical landscapes and innate immune responses in order to successfully colonize and transit between hosts. Therefore, it appears that the intrinsic durability that evolved to make enterococci optimally competitive in the host gastrointestinal tract also ideally positioned them to persist in hospitals, despite disinfection protocols, and acquire new antibiotic resistances from other microbes. Here, we discuss the molecular mechanisms and regulation employed by enterococci to tolerate diverse stressors and highlight the role of stress tolerance in the biology of this medically relevant genus.
Fine RL, Manfredo Vieira S, Gilmore MS, Kriegel MA. Mechanisms and consequences of gut commensal translocation in chronic diseases. Gut Microbes 2019;:1-14.Abstract
Humans and other mammalian hosts have evolved mechanisms to control the bacteria colonizing their mucosal barriers to prevent invasion. While the breach of barriers by bacteria typically leads to overt infection, increasing evidence supports a role for translocation of commensal bacteria across an impaired gut barrier to extraintestinal sites in the pathogenesis of autoimmune and other chronic, non-infectious diseases. Whether gut commensal translocation is a cause or consequence of the disease is incompletely defined. Here we discuss factors that lead to translocation of live bacteria across the gut barrier. We expand upon our recently published demonstration that translocation of the gut pathobiont can induce autoimmunity in susceptible hosts and postulate on the role of species as instigators of chronic, non-infectious diseases.
Fiore E, Van Tyne D, Gilmore MS. Pathogenicity of Enterococci. Microbiol Spectr 2019;7(4)Abstract
Enterococci are unusually well adapted for survival and persistence in a variety of adverse environments, including on inanimate surfaces in the hospital environment and at sites of infection. This intrinsic ruggedness undoubtedly played a role in providing opportunities for enterococci to interact with other overtly drug-resistant microbes and acquire additional resistances on mobile elements. The rapid rise of antimicrobial resistance among hospital-adapted enterococci has rendered hospital-acquired infections a leading therapeutic challenge. With about a quarter of a genome of additional DNA conveyed by mobile elements, there are undoubtedly many more properties that have been acquired that help enterococci persist and spread in the hospital setting and cause diseases that have yet to be defined. Much remains to be learned about these ancient and rugged microbes, particularly in the area of pathogenic mechanisms involved with human diseases.
Dehghan S, Seto J, Liu EB, Ismail AM, Madupu R, Heim A, Jones MS, Dyer DW, Chodosh J, Seto D. A Zoonotic Adenoviral Human Pathogen Emerged through Genomic Recombination among Human and Nonhuman Simian Hosts. J Virol 2019;93(18)Abstract
Genomics analysis of a historically intriguing and predicted emergent human adenovirus (HAdV) pathogen, which caused pneumonia and death, provides insight into a novel molecular evolution pathway involving "ping-pong" zoonosis and anthroponosis. The genome of this promiscuous pathogen is embedded with evidence of unprecedented multiple, multidirectional, stable, and reciprocal cross-species infections of hosts from three species (human, chimpanzee, and bonobo). This recombinant genome, typed as HAdV-B76, is identical to two recently reported simian AdV (SAdV) genomes isolated from chimpanzees and bonobos. Additionally, the presence of a critical adenoviral replication element found in HAdV genomes, in addition to genes that are highly similar to counterparts in other HAdVs, reinforces its potential as a human pathogen. Reservoirs in nonhuman hosts may explain periods of apparent absence and then reemergence of human adenoviral pathogens, as well as present pathways for the genesis of those thought to be newly emergent. The nature of the HAdV-D76 genome has implications for the use of SAdVs as gene delivery vectors in human gene therapy and vaccines, selected to avoid preexisting and potentially fatal host immune responses to HAdV. An emergent adenoviral human pathogen, HAdV-B76, associated with a fatality in 1965, shows a remarkable degree of genome identity with two recently isolated simian adenoviruses that contain cross-species genome recombination events from three hosts: human, chimpanzee, and bonobo. Zoonosis (nonhuman-to-human transmission) and anthroponosis (human to nonhuman transmission) may play significant roles in the emergence of human adenoviral pathogens.
Gaiha GD, Rossin EJ, Urbach J, Landeros C, Collins DR, Nwonu C, Muzhingi I, Anahtar MN, Waring OM, Piechocka-Trocha A, Waring M, Worrall DP, Ghebremichael MS, Newman RM, Power KA, Allen TM, Chodosh J, Walker BD. Structural topology defines protective CD8 T cell epitopes in the HIV proteome. Science 2019;364(6439):480-484.Abstract
Mutationally constrained epitopes of variable pathogens represent promising targets for vaccine design but are not reliably identified by sequence conservation. In this study, we employed structure-based network analysis, which applies network theory to HIV protein structure data to quantitate the topological importance of individual amino acid residues. Mutation of residues at important network positions disproportionately impaired viral replication and occurred with high frequency in epitopes presented by protective human leukocyte antigen () class I alleles. Moreover, CD8 T cell targeting of highly networked epitopes distinguished individuals who naturally control HIV, even in the absence of protective alleles. This approach thereby provides a mechanistic basis for immune control and a means to identify CD8 T cell epitopes of topological importance for rational immunogen design, including a T cell-based HIV vaccine.
Deiner MS, McLeod SD, Wong J, Chodosh J, Lietman TM, Porco TC. Google Searches and Detection of Conjunctivitis Epidemics Worldwide. Ophthalmology 2019;126(9):1219-1229.Abstract
PURPOSE: Epidemic and seasonal infectious conjunctivitis outbreaks can impact education, workforce, and economy adversely. Yet conjunctivitis typically is not a reportable disease, potentially delaying mitigating intervention. Our study objective was to determine if conjunctivitis epidemics could be identified using Google Trends search data. DESIGN: Search data for conjunctivitis-related and control search terms from 5 years and countries worldwide were obtained. Country and term were masked. Temporal scan statistics were applied to identify candidate epidemics. Candidates then were assessed for geotemporal concordance with an a priori defined collection of known reported conjunctivitis outbreaks, as a measure of sensitivity. PARTICIPANTS: Populations by country that searched Google's search engine using our study terms. MAIN OUTCOME MEASURES: Percent of known conjunctivitis outbreaks also found in the same country and period by our candidate epidemics, identified from conjunctivitis-related searches. RESULTS: We identified 135 candidate conjunctivitis epidemic periods from 77 countries. Compared with our a priori defined collection of known reported outbreaks, candidate conjunctivitis epidemics identified 18 of 26 (69% sensitivity) of the reported country-wide or island nationwide outbreaks, or both; 9 of 20 (45% sensitivity) of the reported region or district-wide outbreaks, or both; but far fewer nosocomial and reported smaller outbreaks. Similar overall and individual sensitivity, as well as specificity, were found on a country-level basis. We also found that 83% of our candidate epidemics had start dates before (of those, 20% were more than 12 weeks before) their concurrent reported outbreak's report issuance date. Permutation tests provided evidence that on average, conjunctivitis candidate epidemics occurred geotemporally closer to outbreak reports than chance alone suggests (P < 0.001) unlike control term candidates (P = 0.40). CONCLUSIONS: Conjunctivitis outbreaks can be detected using temporal scan analysis of Google search data alone, with more than 80% detected before an outbreak report's issuance date, some as early as the reported outbreak's start date. Future approaches using data from smaller regions, social media, and more search terms may improve sensitivity further and cross-validate detected candidates, allowing identification of candidate conjunctivitis epidemics from Internet search data potentially to complementarily benefit traditional reporting and detection systems to improve epidemic awareness.
Van Tyne D, Manson AL, Huycke MM, Karanicolas J, Earl AM, Gilmore MS. Impact of antibiotic treatment and host innate immune pressure on enterococcal adaptation in the human bloodstream. Sci Transl Med 2019;11(487)Abstract
Multidrug-resistant enterococcal strains emerged in the early 1980s and are now among the leading causes of drug-resistant bacterial infection worldwide. We used functional genomics to study an early bacterial outbreak in patients in a Wisconsin hospital between 1984 and 1988 that was caused by multidrug-resistant The goal was to determine how a clonal lineage of became adapted to growth and survival in the human bloodstream. Genome sequence analysis revealed a progression of increasingly fixed mutations and repeated independent occurrences of mutations in a relatively small set of genes. Repeated independent mutations suggested selection within the host during the course of infection in response to pressures such as host immunity and antibiotic treatment. We observed repeated independent mutations in a small number of loci, including a little studied polysaccharide utilization pathway and the locus. Functional studies showed that mutating these loci rendered better able to withstand antibiotic pressure and innate immune defenses in the human bloodstream. We also observed a shift in mutation pattern that corresponded to the introduction of carbapenem antibiotics in 1987. This work identifies pathways that allow enterococci to survive the transition from the human gut into the bloodstream, enabling them to cause severe bacteremia associated with high mortality.
Busch C, Iglicki M, Okada M, Gabrielle P-H, Cohen S, Mariussi M, Amphornphruet A, Cebeci Z, Chaikitmongkol V, Couturier A, Fraser-Bell S, Fung AT, Iannetta D, Radecka L, Laíns I, Rodrigues TM, Lupidi M, Ozimek M, Sala-Puigdollers A, Rehak M, Loewenstein A, Zur D, Zur D. Causative Pathogens of Endophthalmitis after Intravitreal Anti-VEGF Injection: An International Multicenter Study. Ophthalmologica 2019;241(4):211-219.Abstract
PURPOSE: The main objective of this study was to investigate the microbiological spectrum of endophthalmitis after anti-VEGF injections and to compare streptococcal with non-streptococcus-associated cases with regard to baseline characteristics and injection procedure. METHODS: Retrospective, international multicenter study of patients with culture-positive endophthalmitis after intravitreal anti-VEGF injection at 17 different retina referral centers. RESULTS: Eighty-three cases with 87 identified pathogens were included. Coagulase-negative staphylococci (59%) and viridans streptococci (15%) were the most frequent pathogens found. The use of postoperative antibiotics and performance of injections in an operating room setting significantly reduced the rate of streptococcus-induced endophthalmitis cases (p = 0.01 for both). CONCLUSION: We found a statistically significant lower rate of postinjectional local antibiotic therapy and operating room-based procedures among the streptococcus-induced cases compared to cases caused by other organisms.
Ramos Y, Rocha J, Hael AL, van Gestel J, Vlamakis H, Cywes-Bentley C, Cubillos-Ruiz JR, Pier GB, Gilmore MS, Kolter R, Morales DK. PolyGlcNAc-containing exopolymers enable surface penetration by non-motile Enterococcus faecalis. PLoS Pathog 2019;15(2):e1007571.Abstract
Bacterial pathogens have evolved strategies that enable them to invade tissues and spread within the host. Enterococcus faecalis is a leading cause of local and disseminated multidrug-resistant hospital infections, but the molecular mechanisms used by this non-motile bacterium to penetrate surfaces and translocate through tissues remain largely unexplored. Here we present experimental evidence indicating that E. faecalis generates exopolysaccharides containing β-1,6-linked poly-N-acetylglucosamine (polyGlcNAc) as a mechanism to successfully penetrate semisolid surfaces and translocate through human epithelial cell monolayers. Genetic screening and molecular analyses of mutant strains identified glnA, rpiA and epaX as genes critically required for optimal E. faecalis penetration and translocation. Mechanistically, GlnA and RpiA cooperated to generate uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) that was utilized by EpaX to synthesize polyGlcNAc-containing polymers. Notably, exogenous supplementation with polymeric N-acetylglucosamine (PNAG) restored surface penetration by E. faecalis mutants devoid of EpaX. Our study uncovers an unexpected mechanism whereby the RpiA-GlnA-EpaX metabolic axis enables production of polyGlcNAc-containing polysaccharides that endow E. faecalis with the ability to penetrate surfaces. Hence, targeting carbohydrate metabolism or inhibiting biosynthesis of polyGlcNAc-containing exopolymers may represent a new strategy to more effectively confront enterococcal infections in the clinic.

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