Infectious Disease

Torkildsen G, Abelson MB, Gomes PJ, McLaurin E, Potts SL, Mah FS. Vehicle-Controlled, Phase 2 Clinical Trial of a Sustained-Release Dexamethasone Intracanalicular Insert in a Chronic Allergen Challenge Model. J Ocul Pharmacol Ther 2017;33(2):79-90.Abstract

PURPOSE: To evaluate the efficacy and safety of a sustained-release dexamethasone intracanalicular insert (Dextenza™) in a model of allergic conjunctivitis. METHODS: This was a randomized, double-masked, vehicle-controlled, Phase 2 study. Subjects had to have a positive conjunctival allergen challenge (CAC) reaction to allergen (bilateral +2 itching and redness on 5-point, 0-4 scales) at Visit 1, and for 2 of 3 time points on subsequent visits. Subjects who met entry criteria were randomized to receive Dextenza or PV (vehicle insert). Challenges occurred over 42 days, with efficacy assessed at 14 (primary endpoint visit), 28, and 40 days postinsertion. Outcome measures included the evaluation of ocular itching, redness, tearing, chemosis, eyelid swelling, rhinorrhea, and congestion. RESULTS: Twenty-eight subjects completed the study in the Dextenza group and 31 in the vehicle group. At 14 days postinsertion, Dextenza was statistically superior to PV, with least square mean differences for ocular itching of -0.76, -0.97, and -0.87 at 3, 5, and 7 min post-CAC, and for conjunctival redness of -0.46, -0.66, and -0.68 at 7, 15, and 20 min post-CAC. Clinical significance, defined as a 1-U decrease from PV, was not met for primary efficacy. Secondary endpoints, including number of subjects reporting itching and conjunctival redness, indicated superior performance of Dextenza compared with vehicle. Eleven Dextenza-treated (35.5%) and 10 vehicle-treated (30.3%) subjects each experienced a single adverse event. CONCLUSION: This Phase 2 study demonstrated preliminary efficacy and safety data of Dextenza for treatment of allergic conjunctivitis.

Drokhlyansky E, Göz Aytürk D, Soh TK, Chrenek R, O'Loughlin E, Madore C, Butovsky O, Cepko CL. The brain parenchyma has a type I interferon response that can limit virus spread. Proc Natl Acad Sci U S A 2017;114(1):E95-E104.Abstract

The brain has a tightly regulated environment that protects neurons and limits inflammation, designated "immune privilege." However, there is not an absolute lack of an immune response. We tested the ability of the brain to initiate an innate immune response to a virus, which was directly injected into the brain parenchyma, and to determine whether this response could limit viral spread. We injected vesicular stomatitis virus (VSV), a transsynaptic tracer, or naturally occurring VSV-derived defective interfering particles (DIPs), into the caudate-putamen (CP) and scored for an innate immune response and inhibition of virus spread. We found that the brain parenchyma has a functional type I interferon (IFN) response that can limit VSV spread at both the inoculation site and among synaptically connected neurons. Furthermore, we characterized the response of microglia to VSV infection and found that infected microglia produced type I IFN and uninfected microglia induced an innate immune response following virus injection.

Zhou X, Ramke M, Chintakuntlawar AV, Lee JY, Rajaiya J, Chodosh J. Role of MyD88 in adenovirus keratitis. Immunol Cell Biol 2017;95(1):108-116.Abstract

Pattern recognition receptors (PRRs) are critical to the early detection and innate immune responses to pathogens. In particular, the toll-like receptor (TLR) system and its associated adaptor proteins have essential roles in early host responses to infection. Epidemic keratoconjunctivitis, caused by the human adenovirus, is a severe ocular surface infection associated with corneal inflammation (stromal keratitis). We previously showed that adenovirus capsid was a key molecular pattern in adenovirus keratitis, with viral DNA having a lesser role. We have now investigated the role of the adaptor molecule MyD88 in a mouse model of adenovirus keratitis in which there is no viral replication. In MyD88(-/-) mice infected with human adenovirus type 37, clinical keratitis was markedly reduced, along with infiltration of CD45(+) cells, and expression of inflammatory cytokines. Reduction of inflammatory cytokines was also observed in infected primary human corneal fibroblasts pretreated with a MyD88 inhibitory peptide. Keratitis similar to wild type mice was observed in TLR2, TLR9 and IL-1R knockout mice, but was reduced in TLR2/9 double knockout mice, consistent with synergy of TLR2 and TLR9 in the response to adenovirus infection. MyD88 co-immunoprecipitated with Src kinase in mice corneas and in human corneal fibroblasts infected with adenovirus, and MyD88 inhibitory peptide reduced Src phosphorylation, linking MyD88 activation to inflammatory gene expression through a signaling cascade previously shown to be directed by Src. Our findings reveal a critical role for the PRRs TLR2 and 9, and their adaptor protein MyD88, in corneal inflammation upon adenovirus infection.

Hodges RR, Li D, Shatos MA, Bair JA, Lippestad M, Serhan CN, Dartt DA. Lipoxin A4 activates ALX/FPR2 receptor to regulate conjunctival goblet cell secretion. Mucosal Immunol 2017;10(1):46-57.Abstract

Conjunctival goblet cells play a major role in maintaining the mucus layer of the tear film under physiological conditions as well as in inflammatory diseases like dry eye and allergic conjunctivitis. Resolution of inflammation is mediated by proresolution agonists such as lipoxin A4 (LXA4) that can also function under physiological conditions. The purpose of this study was to determine the actions of LXA4 on cultured rat conjunctival goblet cell mucin secretion, intracellular [Ca(2+)] ([Ca(2+)]i), and identify signaling pathways activated by LXA4. ALX/FPR2 (formyl peptide receptor2) was localized to goblet cells in rat conjunctiva and in cultured goblet cells. LXA4 significantly increased mucin secretion, [Ca(2+)]i, and extracellular regulated kinase 1/2 (ERK 1/2) activation. These functions were inhibited by ALX/FPR2 inhibitors. Stable analogs of LXA4 increased [Ca(2+)]i to the same extent as LXA4. Sequential addition of either LXA4 or resolvin D1 followed by the second compound decreased [Ca(2+)]i of the second compound compared with its initial response. LXA4 activated phospholipases C, D, and A2 and downstream molecules protein kinase C, ERK 1/2, and Ca(2+)/calmodulin-dependent kinase to increase mucin secretion and [Ca(2+)]i. We conclude that conjunctival goblet cells respond to LXA4 to maintain the homeostasis of the ocular surface and could be a novel treatment for dry eye diseases.

Yu Z, Zeng Z, Zhang J, Pan Y, Chen M, Guo Y, Yu N, Chodosh J, Fu N, Che X, Zhang Q. Fatal Community-acquired Pneumonia in Children Caused by Re-emergent Human Adenovirus 7d Associated with Higher Severity of Illness and Fatality Rate. Sci Rep 2016;6:37216.Abstract

Human adenoviruses (HAdVs) are highly contagious pathogens causing acute respiratory disease (ARD), such as community-acquired pneumonia. HAdV-7d, a re-emergent genomic variant, has been recently reported in Asia and the United States after a several-decade absence. However, whether HAdV-7d is associated with higher severity than other types is currently unclear. In this study, the clinical and epidemiological investigation showed that fever, cough, and sore throat were the three most common respiratory symptoms of HAdV infections. HAdV-7 caused longer duration of fever, higher morbidity of tachypnea/dyspnea, pleural effusion, diarrhea, hepatosplenomegaly, consciousness alteration, as well as higher rates of pneumonia, mechanical ventilation and higher fatality rate (28.6%) than other types, particularly HAdV-3 and HAdV-2. The genomes of seven HAdV-7d isolates from mild, severe, and fatal cases were sequenced and highly similar with each other. Surprisingly, two isolates (2011, 2012) had 100% identical genomes with an earlier strain from a fatal ARD outbreak in China (2009), which elucidates the virus origin and confirms the unexpected HAdV genomic conservation and stability. Phylogenetic analysis indicated that L1 52/55-kDa DNA packaging protein may be associated with the higher severity of illness and fatality rate of HAdV-7. Clinicians need to be aware of HAdVs in children with ARD.

Gupta M, Jardeleza MSR, Kim I, Durand ML, Kim L, Lobo A-M. Varicella Zoster Virus Necrotizing Retinitis in Two Patients with Idiopathic CD4 Lymphocytopenia. Ocul Immunol Inflamm 2016;24(5):544-8.Abstract

PURPOSE: Progressive outer retinal necrosis (PORN) associated with varicella zoster virus (VZV) is usually diagnosed in HIV positive or immunosuppressed patients. We report two cases of immunocompetent patients with necrotizing viral retinitis found to have idiopathic CD4 lymphocytopenia. METHODS: Clinical presentation, examination, imaging, and laboratory testing of two patients with VZV retinitis are presented. RESULTS: An HIV negative patient with history of herpes zoster presented with rapid loss of vision and examination consistent with PORN. PCR testing confirmed VZV. Lymphocytopenia was noted with a CD4 count of 25/mm(3). A second HIV negative patient presented with blurred vision and lid swelling and was found to have peripheral VZV retinitis confirmed by PCR. Laboratory workup revealed lymphocytopenia with a CD4 count of 133/mm(3). CONCLUSIONS: VZV necrotizing retinitis classic for PORN can occur in HIV negative patients. Idiopathic CD4 lymphocytopenia should be considered healthy patients who develop ocular infections seen in the immunocompromised.

de Mello SS, Van Tyne D, Dabul ANG, Gilmore MS, Camargo ILBC. High-Quality Draft Genome Sequence of the Multidrug-Resistant Clinical Isolate Enterococcus faecium VRE16. Genome Announc 2016;4(5)Abstract

Specific lineages of the commensal bacterium Enterococcus faecium belonging to CC17, especially ST412, have been isolated from patients in several hospitals worldwide and harbor antibiotic resistance genes and virulence factors. Here, we report a high-quality draft genome sequence and highlight features of E. faecium VRE16, a representative of this ST.

Van Tyne D, Ciolino JB, Wang J, Durand ML, Gilmore MS. Novel Phagocytosis-Resistant Extended-Spectrum β-Lactamase-Producing Escherichia coli From Keratitis. JAMA Ophthalmol 2016;134(11):1306-1309.Abstract

Importance: Extended-spectrum β-lactamase (ESBL)-producing Escherichia coli are highly antibiotic resistant, and primary ocular infection by ESBL E coli has rarely been reported. A novel mutation conferring phagocytosis resistance would position a strain well to infect the cornea. Observations: A woman with recurrent keratitis presented with a corneal ulcer, which was culture positive for ESBL E coli. Resistant to nearly all other antimicrobials, the infection was treated with amikacin and polymyxin B-trimethoprim, and the ulcer resolved over 3 weeks. Analysis of the E coli genome showed it to belong to multilocus sequence type 131 (ST131). This isolate was found to possess a novel deletion in yrfF, an essential regulator of bacterial capsule synthesis. Disruption of yrfF, which confers mucoidy and increased virulence, has not been previously observed in ESBL E coli from any infection site. This novel variant was experimentally proven to cause the mucoid phenotype, and corresponding resistance to phagocytic killing. Conclusions and Relevance: Increased resistance to immune clearance in an ESBL E coli lineage already known for its virulence is an unsettling development. This phenotype, which likely positioned it as an unusual cause of corneal ulcer, can be easily recognized in the laboratory, which should help limit its spread.

Rajagopal M, Martin MJ, Santiago M, Lee W, Kos VN, Meredith T, Gilmore MS, Walker S. Multidrug Intrinsic Resistance Factors in Staphylococcus aureus Identified by Profiling Fitness within High-Diversity Transposon Libraries. MBio 2016;7(4)Abstract

UNLABELLED: Staphylococcus aureus is a leading cause of life-threatening infections worldwide. The MIC of an antibiotic against S. aureus, as well as other microbes, is determined by the affinity of the antibiotic for its target in addition to a complex interplay of many other cellular factors. Identifying nontarget factors impacting resistance to multiple antibiotics could inform the design of new compounds and lead to more-effective antimicrobial strategies. We examined large collections of transposon insertion mutants in S. aureus using transposon sequencing (Tn-Seq) to detect transposon mutants with reduced fitness in the presence of six clinically important antibiotics-ciprofloxacin, daptomycin, gentamicin, linezolid, oxacillin, and vancomycin. This approach allowed us to assess the relative fitness of many mutants simultaneously within these libraries. We identified pathways/genes previously known to be involved in resistance to individual antibiotics, including graRS and vraFG (graRS/vraFG), mprF, and fmtA, validating the approach, and found several to be important across multiple classes of antibiotics. We also identified two new, previously uncharacterized genes, SAOUHSC_01025 and SAOUHSC_01050, encoding polytopic membrane proteins, as important in limiting the effectiveness of multiple antibiotics. Machine learning identified similarities in the fitness profiles of graXRS/vraFG, SAOUHSC_01025, and SAOUHSC_01050 mutants upon antibiotic treatment, connecting these genes of unknown function to modulation of crucial cell envelope properties. Therapeutic strategies that combine a known antibiotic with a compound that targets these or other intrinsic resistance factors may be of value for enhancing the activity of existing antibiotics for treating otherwise-resistant S. aureus strains. IMPORTANCE: Bacterial resistance to every major class of antibiotics has emerged, and we are entering a "post-antibiotic era" where relatively minor infections can lead to serious complications or even death. The utility of an antibiotic for a specific pathogen is limited by both intrinsic and acquired factors. Identifying the repertoire of intrinsic resistance factors of an antibiotic for Staphylococcus aureus, a leading cause of community- and hospital-acquired infections, would inform the design of new drugs as well as the identification of compounds that enhance the activity of existing drugs. To identify factors that limit the activity of antibiotics against S. aureus, we used Tn-Seq to simultaneously assess fitness of transposon mutants in every nonessential gene in the presence of six clinically important antibiotics. This work provides an efficient approach for identifying promising targets for drugs that can enhance susceptibility or restore sensitivity to existing antibiotics.

Selleck EM, Gilmore MS. Oxygen as a Virulence Determinant in Polymicrobial Infections. MBio 2016;7(4)Abstract

Infections caused by multiple organisms, or polymicrobial infections, are likely more common than is broadly appreciated. Interaction among microbial communities (and with their host) can change the infection landscape by subverting immunity, providing nutrients and inhibiting competing microbes. Stacy et al. (A. Stacy, D. Fleming, R. J. Lamont, K. P. Rumbaugh, and M. Whiteley, mBio 7:e00782-16, 2016, http://dx.doi.org/10.1128/mBio.00782-16) described a novel mechanism that results in synergistic growth of oral microbes Aggregatibacter actinomycetemcomitans and Streptococcus gordonii The authors used whole-genome fitness profiling by transposon sequencing (Tn-seq) to identify genes differentially required for growth in vitro versus in a mono- or coinfection in a thigh abscess model. They found that coinfection with S. gordonii allowed A. actinomycetemcomitans to shift from an anaerobic to an aerobic mode of growth. This shift involved the production of a terminal electron acceptor H2O2 by S. gordonii and increased A. actinomycetemcomitans persistence-an interaction termed "cross-respiration."

Cho H, Shin YU, Siegel NH, Yu HG, Sobrin L, Patel A, Durand ML, Miller JW, Husain D. Endogenous Endophthalmitis in the American and Korean Population: An 8-year Retrospective Study. Ocul Immunol Inflamm 2016;:1-8.Abstract

PURPOSE: To study the clinical features of endogenous endophthalmitis (EE) in sample patient populations from the USA and South Korea over an 8-year period. METHODS: We reviewed data from 128 eyes of 60 American and 48 Korean patients diagnosed with EE and compared their clinical characteristics. RESULTS: Fungemia and liver abscess were the most common extraocular infection sources among American (26.7%) and Korean patients (33.3%), respectively. Klebsiella pneumoniae and Candida species were the most common pathogens of EE in the Korean and the American patients, respectively. Endophthalmitis caused by fungi had a better visual prognosis than that caused by bacteria (p = 0.001). Vitrectomy was beneficial for eyes with EE due to virulent bacteria presenting with worse than counting finger vision. CONCLUSIONS: The predisposing conditions and responsible organisms for EE vary in different regions of the world. The visual prognosis was strongly influenced by the underlying pathogen.

García-Solache M, Lebreton F, McLaughlin RE, Whiteaker JD, Gilmore MS, Rice LB. Homologous Recombination within Large Chromosomal Regions Facilitates Acquisition of β-Lactam and Vancomycin Resistance in Enterococcus faecium. Antimicrob Agents Chemother 2016;60(10):5777-86.Abstract

The transfer of DNA between Enterococcus faecium strains has been characterized both by the movement of well-defined genetic elements and by the large-scale transfer of genomic DNA fragments. In this work, we report on the whole-genome analysis of transconjugants resulting from mating events between the vancomycin-resistant E. faecium C68 strain and the vancomycin-susceptible D344RRF strain to discern the mechanism by which the transferred regions enter the recipient chromosome. Vancomycin-resistant transconjugants from five independent matings were analyzed by whole-genome sequencing. In all cases but one, the penicillin binding protein 5 (pbp5) gene and the Tn5382 vancomycin resistance transposon were transferred together and replaced the corresponding pbp5 region of D344RRF. In one instance, Tn5382 inserted independently downstream of the D344RRF pbp5 gene. Single nucleotide variant (SNV) analysis suggested that entry of donor DNA into the recipient chromosome occurred by recombination across regions of homology between donor and recipient chromosomes, rather than through insertion sequence-mediated transposition. The transfer of genomic DNA was also associated with the transfer of C68 plasmid pLRM23 and another putative plasmid. Our data are consistent with the initiation of transfer by cointegration of a transferable plasmid with the donor chromosome, with subsequent circularization of the plasmid-chromosome cointegrant in the donor prior to transfer. Entry into the recipient chromosome most commonly occurred across regions of homology between donor and recipient chromosomes.

Jain R, Sharma N, Basu S, Iyer G, Ueta M, Sotozono C, Kannabiran C, Rathi VM, Gupta N, Kinoshita S, Gomes JAP, Chodosh J, Sangwan VS. Stevens-Johnson syndrome: The role of an ophthalmologist. Surv Ophthalmol 2016;61(4):369-99.Abstract

Stevens-Johnson syndrome (SJS) is an acute blistering disease of the skin and mucous membranes. Acute SJS leads to the acute inflammation of the ocular surface and chronic conjunctivitis. If not properly treated, it causes chronic cicatricial conjunctivitis and cicatricial lid margin abnormalities. Persistent inflammation and ulceration of the ocular surface with cicatricial complications of the lids leads to chronic ocular sequelae, ocular surface damage, and corneal scarring. The destruction of the glands that secrete the tear film leads to a severe form of dry eye that makes the management of chronic SJS difficult. The option that is routinely used for corneal visual rehabilitation, keratoplasty, is best avoided in such cases. We describe the management strategies that are most effective during the acute and chronic stages of SJS. Although treatments for acute SJS involve immunosuppressive and immunomodulatory therapies, amniotic membrane transplantation is also useful. The options for visual rehabilitation in patients with chronic SJS are undergoing radical change. We describe the existing literature regarding the management of SJS and highlight recent advances in the management of this disorder.

Deiner MS, Lietman TM, McLeod SD, Chodosh J, Porco TC. Surveillance Tools Emerging From Search Engines and Social Media Data for Determining Eye Disease Patterns. JAMA Ophthalmol 2016;134(9):1024-30.Abstract

IMPORTANCE: Internet-based search engine and social media data may provide a novel complementary source for better understanding the epidemiologic factors of infectious eye diseases, which could better inform eye health care and disease prevention. OBJECTIVE: To assess whether data from internet-based social media and search engines are associated with objective clinic-based diagnoses of conjunctivitis. DESIGN, SETTING, AND PARTICIPANTS: Data from encounters of 4143 patients diagnosed with conjunctivitis from June 3, 2012, to April 26, 2014, at the University of California San Francisco (UCSF) Medical Center, were analyzed using Spearman rank correlation of each weekly observation to compare demographics and seasonality of nonallergic conjunctivitis with allergic conjunctivitis. Data for patient encounters with diagnoses for glaucoma and influenza were also obtained for the same period and compared with conjunctivitis. Temporal patterns of Twitter and Google web search data, geolocated to the United States and associated with these clinical diagnoses, were compared with the clinical encounters. The a priori hypothesis was that weekly internet-based searches and social media posts about conjunctivitis may reflect the true weekly clinical occurrence of conjunctivitis. MAIN OUTCOMES AND MEASURES: Weekly total clinical diagnoses at UCSF of nonallergic conjunctivitis, allergic conjunctivitis, glaucoma, and influenza were compared using Spearman rank correlation with equivalent weekly data on Tweets related to disease or disease-related keyword searches obtained from Google Trends. RESULTS: Seasonality of clinical diagnoses of nonallergic conjunctivitis among the 4143 patients (2364 females [57.1%] and 1776 males [42.9%]) with 5816 conjunctivitis encounters at UCSF correlated strongly with results of Google searches in the United States for the term pink eye (ρ, 0.68 [95% CI, 0.52 to 0.78]; P < .001) and correlated moderately with Twitter results about pink eye (ρ, 0.38 [95% CI, 0.16 to 0.56]; P < .001) and with clinical diagnosis of influenza (ρ, 0.33 [95% CI, 0.12 to 0.49]; P < .001), but did not significantly correlate with seasonality of clinical diagnoses of allergic conjunctivitis diagnosis at UCSF (ρ, 0.21 [95% CI, -0.02 to 0.42]; P = .06) or with results of Google searches in the United States for the term eye allergy (ρ, 0.13 [95% CI, -0.06 to 0.32]; P = .19). Seasonality of clinical diagnoses of allergic conjunctivitis at UCSF correlated strongly with results of Google searches in the United States for the term eye allergy (ρ, 0.44 [95% CI, 0.24 to 0.60]; P < .001) and eye drops (ρ, 0.47 [95% CI, 0.27 to 0.62]; P < .001). CONCLUSIONS AND RELEVANCE: Internet-based search engine and social media data may reflect the occurrence of clinically diagnosed conjunctivitis, suggesting that these data sources can be leveraged to better understand the epidemiologic factors of conjunctivitis.

Ismail AM, Lee JS, Dyer DW, Seto D, Rajaiya J, Chodosh J. Selection Pressure in the Human Adenovirus Fiber Knob Drives Cell Specificity in Epidemic Keratoconjunctivitis. J Virol 2016;90(21):9598-9607.Abstract

Human adenoviruses (HAdVs) contain seven species (HAdV-A to -G), each associated with specific disease conditions. Among these, HAdV-D includes those viruses associated with epidemic keratoconjunctivitis (EKC), a severe ocular surface infection. The reasons for corneal tropism for some but not all HAdV-Ds are not known. The fiber protein is a major capsid protein; its C-terminal "knob" mediates binding with host cell receptors to facilitate subsequent viral entry. In a comprehensive phylogenetic analysis of HAdV-D capsid genes, fiber knob gene sequences of HAdV-D types associated with EKC formed a unique clade. By proteotyping analysis, EKC virus-associated fiber knobs were uniquely shared. Comparative structural modeling showed no distinct variations in fiber knobs of EKC types but did show variation among HAdV-Ds in a region overlapping with the known CD46 binding site in HAdV-B. We also found signature amino acid positions that distinguish EKC from non-EKC types, and by in vitro studies we showed that corneal epithelial cell tropism can be predicted by the presence of a lysine or alanine at residue 240. This same amino acid residue in EKC viruses shows evidence for positive selection, suggesting that evolutionary pressure enhances fitness in corneal infection, and may be a molecular determinant in EKC pathogenesis. IMPORTANCE: Viruses adapt various survival strategies to gain entry into target host cells. Human adenovirus (HAdV) types are associated with distinct disease conditions, yet evidence for connections between genotype and cellular tropism is generally lacking. Here, we provide a structural and evolutionary basis for the association between specific genotypes within HAdV species D and epidemic keratoconjunctivitis, a severe ocular surface infection. We find that HAdV-D fiber genes of major EKC pathogens, specifically the fiber knob gene region, share a distinct phylogenetic clade. Deeper analysis of the fiber gene revealed that evolutionary pressure at crucial amino acid sites has a significant impact on its structural conformation, which is likely important in host cell binding and entry. Specific amino acids in hot spot residues provide a link to ocular cell tropism and possibly to corneal pathogenesis.

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