PURPOSE: To evaluate the safety and efficacy of topical tacrolimus 0.05% versus topical methylprednisolone 0.5% in patients with ocular graft-versus-host disease (GVHD). DESIGN: Phase 1/2 prospective, randomized, double-masked clinical trial. PARTICIPANTS: Eighty eyes of 40 patients diagnosed with chronic ocular GVHD were enrolled. METHODS: Forty patients with ocular GVHD were randomized; 24 patients were treated with topical tacrolimus 0.05% and 16 patients were treated with topical methylprednisolone 0.5% twice daily for 10 weeks, in addition to continuing their baseline treatment regimen. MAIN OUTCOME MEASURES: Safety was evaluated based on occurrence of adverse events. Tolerability was assessed based on subject reports of discomfort after drop instillation. Intraocular pressure (IOP) was monitored. The main efficacy end points were corneal fluorescein staining (CFS), tear film break-up time (TBUT), Schirmer test results, and expression of the ocular surface inflammatory markers human leukocyte antigen-DR (HLA-DR) and intercellular adhesion molecule-1 (ICAM-1). Symptoms were evaluated using the Ocular Surface Disease Index (OSDI). RESULTS: After 10 weeks of treatment, no major adverse events occurred in either treatment group, and there was no significant difference in the composite tolerability scores between the 2 groups (P = 0.06). However, burning sensation was more pronounced with tacrolimus (P = 0.002). Topical tacrolimus was more effective than methylprednisolone in reducing the CFS score at week 10 (55% vs. 23% reduction, respectively; P = 0.01) and achieved significant improvement in TBUT when compared with baseline (P < 0.001). Reduction in OSDI score achieved statistical significance with tacrolimus (27% reduction; P = 0.02), but was marginal with methylprednisolone (32% reduction; P = 0.06). Expression of ICAM-1 by ocular surface epithelium decreased significantly in both groups (tacrolimus, P = 0.003; methylprednisolone, P = 0.008), whereas HLA-DR expression decreased significantly only in the tacrolimus group (P = 0.03). Schirmer test scores did not change significantly in either group during the study; IOP increased significantly with methylprednisolone at week 10 (P = 0.04). CONCLUSIONS: Topical tacrolimus 0.05% is safe, generally well tolerated, and effective for the treatment of ocular GVHD without the hypertensive effects of topical corticosteroids.
Uveitis is a common and serious complication of juvenile idiopathic arthritis. Up to 75% of all cases of anterior uveitis in childhood are associated with juvenile idiopathic arthritis. Despite the remarkable progress in early detection and treatment of inflammation, vision-threatening complications of uveitis still occur in almost 60% of patients. Structural complications include band keratopathy, maculopathy (macular edema, macular cysts, and epiretinal membrane), glaucomatous optic neuropathy, and cataracts. The management of complications in juvenile idiopathic arthritis is usually complex and requires early surgical intervention. In this paper, we review the general concepts of common ocular complications seen in patients with JIA-associated uveitis, with special attention to the recent diagnostic and preferred treatment approaches at the Massachusetts Eye Research and Surgery Institution. Received 9 March 2015; revised 30 September 2015; accepted 30 October 2015; published online 14 January 2016.
Recent clinical research has highlighted important links between a number of diseases and the tortuosity of curvilinear anatomical structures like corneal nerve fibres, suggesting that tortuosity changes might detect early stages of specific conditions. Currently, clinical studies are mainly based on subjective, visual assessment, with limited repeatability and inter-observer agreement. To address these problems, we propose a fully automated framework for image-level tortuosity estimation, consisting of a hybrid segmentation method and a highly adaptable, definition-free tortuosity estimation algorithm. The former combines an appearance model, based on a Scale and Curvature-Invariant Ridge Detector (SCIRD), with a context model, including multi-range learned context filters. The latter is based on a novel tortuosity estimation paradigm in which discriminative, multi-scale features can be automatically learned for specific anatomical objects and diseases. Experimental results on 140 in vivo confocal microscopy images of corneal nerve fibres from healthy and unhealthy subjects demonstrate the excellent performance of our method compared to state-of-the-art approaches and ground truth annotations from 3 expert observers.
Driving is an important rehabilitation goal for patients with homonymous field defects (HFDs); however, whether or not people with HFDs should be permitted to drive is not clear. Over the last 15 years, there has been a marked increase in the number of studies evaluating the effects of HFDs on driving performance. This review of the literature provides a much-needed summary for practitioners and researchers, addressing the following topics: regulations pertaining to driving with HFDs, self-reported driving difficulties, pass rates in on-road tests, the effects of HFDs on lane position and steering stability, the effects of HFDs on scanning and detection of potential hazards, screening for potential fitness to drive, evaluating practical fitness to drive and the efficacy of interventions to improve driving of persons with HFDs. Although there is clear evidence from on-road studies that some people with HFDs may be rated as safe to drive, others are reported to have significant deficits in skills important for safe driving, including taking a lane position too close to one side of the travel lane, unstable steering and inadequate viewing (scanning) behaviour. Driving simulator studies have provided strong evidence of a wide range in compensatory scanning abilities and detection performance, despite similar amounts of visual field loss. Conventional measurements of visual field extent (in which eye movements are not permitted) do not measure such compensatory abilities and are not predictive of on-road driving performance. Thus, there is a need to develop better tests to screen people with HFDs for visual fitness to drive. We are not yet at a point where we can predict which HFD patient is likely to be a safe driver. Therefore, it seems only fair to provide an opportunity for individualised assessments of practical fitness to drive either on the road and/or in a driving simulator.
PURPOSE OF REVIEW: Review recent advances in clinical and experimental studies of dominant optic atrophy (DOA) to better understand the complexities of pathophysiology caused by the optic atrophy 1 (OPA1) mutation. RECENT FINDINGS: DOA is the most commonly diagnosed inherited optic atrophy, causing progressive bilateral visual loss that begins early in life. During the past 25 years, there has been substantial progress in the understanding of the clinical, genetic, and pathophysiological basis of this disease. The histopathological hallmark of DOA is the primary degeneration of retinal ganglion cells, preferentially in the papillomacular bundle, which results temporal optic disc pallor and cecocentral scotomata in patients with DOA. Loss of OPA1 protein function by OPA1 gene mutations causes mitochondrial dysfunction because of the loss of mitochondrial fusion, impaired mitochondrial oxidative phosphorylation, increases in reactive oxygen species, and altered calcium homeostasis. These factors lead to apoptosis of retinal ganglion cells by a haploinsufficiency mechanism. SUMMARY: Improved understanding of the pathophysiology of DOA provides insights that can be used to develop therapeutic approaches to the DOA.
AIMS: To describe and compare clinical features, complications and outcomes in patients with granulomatosis with polyangiitis (GPA)-associated scleritis with those seen in idiopathic and other autoimmune-associated scleritis, and to further describe the features that may serve as an indicator of life-threatening systemic disease. METHODS: We retrospectively reviewed electronic health records of all patients with scleritis seen at two tertiary care centres. Of 500 patients, 14 had GPA-associated scleritis and were included in this analysis. Measures included were age, gender, laterality, visual acuity and underlying systemic or ocular diseases. Clinical features (location, pain, inflammation) and ocular complications of these patients (decrease of vision, concomitant anterior uveitis and ocular hypertension) were studied and correlated. RESULTS: Fourteen of 500 patients with scleritis were GPA associated. Most of the patients with GPA-associated scleritis presented with sudden onset, bilateral, diffuse anterior scleral inflammation, with moderate-or-severe pain. Vision loss was not significantly different, and pain was more severe in these patients than in those with idiopathic scleritis. When compared with patients with other underlying autoimmune diseases, there were no significant differences found in epidemiological or clinical signs. Necrotising scleritis and corneal involvement were more commonly observed in GPA than in idiopathic scleritis and other autoimmune diseases and are often the presenting feature of the disease. CONCLUSIONS: The presence of necrotising changes or corneal involvement in the setting of scleral inflammation is highly suggestive of an underlying systemic vasculitis, of which GPA is the most common. These features should alert the doctor/optometrist and prompt a thorough diagnostic approach and an aggressive treatment given that it could reveal a life-threatening disease.
PURPOSE: To develop diagnostic criteria for nonparaneoplastic autoimmune retinopathy (AIR) through expert panel consensus and to examine treatment patterns among clinical experts. DESIGN: Modified Delphi process. METHODS: A survey of uveitis specialists in the American Uveitis Society, a face-to-face meeting (AIR Workshop) held at the National Eye Institute, and 2 iterations of expert panel surveys were used in a modified Delphi process. The expert panel consisted of 17 experts, including uveitis specialists and researchers with expertise in antiretinal antibody detection. Supermajority consensus was used and defined as 75% of experts in agreement. RESULTS: There was unanimous agreement among experts regarding the categorization of autoimmune retinopathies as nonparaneoplastic and paraneoplastic, including cancer-associated retinopathy and melanoma-associated retinopathy. Diagnostic criteria and tests essential to the diagnosis of nonparaneoplastic AIR and multiple supportive criteria reached consensus. For treatment, experts agreed that corticosteroids and conventional immunosuppressives should be used (prescribed) as first- or second-line treatments, though a consensus agreed that biologics and intravenous immunoglobulin were considered appropriate in the treatment of nonparaneoplastic AIR patients regardless of the stage of disease. Experts agreed that more evidence is needed to treat nonparaneoplastic AIR patients with long-term immunomodulatory therapy and that there is enough equipoise to justify randomized, placebo-controlled trials to determine if nonparaneoplastic AIR patients should be treated with long-term immunomodulatory therapy. Regarding antiretinal antibody detection, consensus agreed that a standardized assay system is needed to detect serum antiretinal antibodies. Consensus agreed that an ideal assay should have a 2-tier design and that Western blot and immunohistochemistry should be the methods used to identify antiretinal antibodies. CONCLUSIONS: Consensus was achieved using a modified Delphi process to develop diagnostic criteria for nonparaneoplastic AIR. There is enough equipoise to justify randomized, placebo-controlled trials to determine whether patients with nonparaneoplastic AIR should be treated with long-term immunomodulatory therapy. Efforts to develop a standardized 2-tier assay system for the detection of antiretinal antibodies have been initiated as a result of this study.
Neovascular eye diseases are a major cause of blindness including retinopathy of prematurity, diabetic retinopathy and age-related macular degeneration in which new vessel formation is driven by hypoxia or metabolic abnormalities affecting the fuel supply. White-adipose-tissue derived adipokines such as adiponectin modulate metabolic responses. Increasing evidence shows that lack of adiponectin may result in retinal neovascularization. Activation of the adiponectin pathway may in turn restore energy metabolism, to suppress the drive for compensatory but ultimately pathological neovessels of retinopathy. In this review, we will summarize our current knowledge of the role of adiponectin in eye diseases of premature infants, diabetic patients as well as the elderly. Further investigations in this field are likely to lead to new preventative approaches for these diseases.
PURPOSE OF REVIEW: Nonarteritic anterior ischemic optic neuropathy (NAION) is the most common cause of acute optic nerve injury, and frequently presents to comprehensive ophthalmologists. We review the typical and atypical clinical features and current literature on various treatment modalities for NAION. RECENT FINDINGS: The epidemiology and clinical presentation of this disease can be variable, making a definitive diagnosis difficult in many cases. In addition, the differential diagnoses for this disorder, although comprising much less prevalent entities, are quite broad and can have substantial systemic implications if these alternatives go unrecognized. NAION has many systemic associations and comorbidities that deserve inquiry when the diagnosis is made. There are currently no widely accepted, evidence-based treatments for NAION. All recommendations made to patients to reduce their risk of sequential eye involvement, including avoidance of potential nocturnal hypotension, erectile dysfunction medication, and treatment of obstructive sleep apnea, have theoretical bases. SUMMARY: NAION is a common cause of acute vision loss in adult and older patients, and thus, comprehensive ophthalmologists need to be able to diagnose and appropriately manage this disorder. We anticipate fruitful results from current and future trials aimed at neuroprotection in the affected eye and prevention of sequential eye involvement.
PURPOSE OF REVIEW: Papilledema associated with idiopathic intracranial hypertension (IIH) may result in irreversible, progressive visual loss. The development of tools for the evaluation of pediatric patients with IIH is particularly relevant as many patients may not be able to comply with the detailed clinical evaluation utilized in adults for the treatment and management of this disease. The purpose of this review is to summarize relevant articles on the diagnostic tools used in evaluation and management of pediatric IIH. RECENT FINDINGS: Studies suggest that characteristic pediatric IIH MRI findings include empty sella turcica, decreased pituitary gland size, optic nerve tortuosity, perioptic subarachnoid space enlargement, posterior globe flattering, and intraocular protrusion of the optic nerve head. On optical coherence tomography (OCT), increased retinal nerve fiber layer and macular thickness may be observed in children with IIH compared with controls. The retinal nerve fiber layer thickness seems to coincide with the severity of papilledema and may be more sensitive than funduscopy for detecting optic nerve head elevation. Research on ultrasound of the optic nerve shows increased size of the optic nerve sheath diameter in pediatric IIH patients, and this may correlate with increased opening pressure on lumbar puncture. SUMMARY: There appears to be characteristic findings on MRI, OCT, and ultrasound studies in pediatric IIH patients. Although ultrasound is rarely used for monitoring these patients nowadays, MRI and OCT can be useful in the evaluation and management of these individuals.
: In humans, the lacrimal gland (LG) is the primary contributor to the aqueous layer of the tear film. Production of tears in insufficient quantity or of inadequate quality may lead to aqueous-deficiency dry eye (ADDE). Currently there is no cure for ADDE. The development of strategies to reliably isolate LG stem/progenitor cells from the LG tissue brings great promise for the design of cell replacement therapies for patients with ADDE. We analyzed the therapeutic potential of epithelial progenitor cells (EPCPs) isolated from adult wild-type mouse LGs by transplanting them into the LGs of TSP-1(-/-) mice, which represent a novel mouse model for ADDE. TSP-1(-/-) mice are normal at birth but progressively develop a chronic form of ocular surface disease, characterized by deterioration, inflammation, and secretory dysfunction of the lacrimal gland. Our study shows that, among c-kit-positive epithelial cell adhesion molecule (EpCAM(+)) populations sorted from mouse LGs, the c-kit(+)dim/EpCAM(+)/Sca1(-)/CD34(-)/CD45(-) cells have the hallmarks of an epithelial cell progenitor population. Isolated EPCPs express pluripotency factors and markers of the epithelial cell lineage Runx1 and EpCAM, and they form acini and ducts when grown in reaggregated three-dimensional cultures. Moreover, when transplanted into injured or "diseased" LGs, they engraft into acinar and ductal compartments. EPCP-injected TSP-1(-/-) LGs showed reduction of cell infiltration, differentiation of the donor EPCPs within secretory acini, and substantial improvement in LG structural integrity and function. This study provides the first evidence for the effective use of adult EPCP cell transplantation to rescue LG dysfunction in a model system. SIGNIFICANCE: In humans, the lacrimal gland is the primary contributor to the aqueous layer of the tear film. Damage or inflammation of the lacrimal gland may lead to severe aqueous-deficiency dry eye and corneal disease. Endogenous lacrimal gland epithelial cell progenitors (EPCPs) injected into the gland of mouse model of human Sjögren's syndrome TSP-1(-/-) mice resulted in long-term engraftment and markedly improved structure and function of "diseased" lacrimal gland. This study demonstrates, for the first time, that EPCPs can mediate functional recovery of the lacrimal gland in a Sjögren's syndrome mouse model. These data establish proof of concept that endogenous stem/progenitor cell transplantation may be used to treat human lacrimal gland chronic inflammation.
Importance: Medulloepithelioma is the second most common primary neuroepithelial tumor of the eye. The full range of its morphologic expressions and appearances in metastases have not been fully explored. Observations: A patient in her 50s with glaucoma for decades had undergone multiple filtering surgical procedures, including the placement of a glaucoma drainage device. A paraspinal mass was discovered, and tumor and bone marrow biopsies disclosed rhabdomyosarcoma. This led to the discovery of a multicystic intraocular tumor. A metastatic rhabdomyosarcoma to the eye was considered unlikely because, to our knowledge, this event had never been reported. An enucleation was performed, and an intraocular tumor composed almost entirely of rhabdomyoblasts (desmin- and myogenin-positive) was discovered along with rare clusters of persistent neuroepithelial cells. Conclusions and Relevance: To our knowledge, this is the first case of a medulloepithelioma in which teratoid rhabdomyoblasts effaced all but trace amounts of neuroepithelium and generated a distant metastasis entirely composed of rhabdomyoblasts. The prolonged history and filtering procedures probably led to these 2 phenomena.
Joshi AD, Andersson C, Buch S, Stender S, Noordam R, Weng L-C, Weeke PE, Auer PL, Boehm B, Chen C, Choi H, Curhan G, Denny JC, De Vivo I, Eicher JD, Ellinghaus D, Folsom AR, Fuchs C, Gala M, Haessler J, Hofman A, Hu F, Hunter DJ, Janssen HLA, Kang JH, Kooperberg C, Kraft P, Kratzer W, Lieb W, Lutsey PL, Darwish Murad S, Nordestgaard BG, Pasquale LR, Reiner AP, Ridker PM, Rimm E, Rose LM, Shaffer CM, Schafmayer C, Tamimi RM, Uitterlinden AG, Völker U, Völzke H, Wakabayashi Y, Wiggs JL, Zhu J, Roden DM, Stricker BH, Tang W, Teumer A, Hampe J, Tybjærg-Hansen A, Chasman DI, Chan AT, Johnson AD. Four Susceptibility Loci for Gallstone Disease Identified in a Meta-analysis of Genome-Wide Association Studies. Gastroenterology 2016;151(2):351-363.e28.Abstract
BACKGROUND & AIMS: A genome-wide association study (GWAS) of 280 cases identified the hepatic cholesterol transporter ABCG8 as a locus associated with risk for gallstone disease, but findings have not been reported from any other GWAS of this phenotype. We performed a large-scale, meta-analysis of GWASs of individuals of European ancestry with available prior genotype data, to identify additional genetic risk factors for gallstone disease. METHODS: We obtained per-allele odds ratio (OR) and standard error estimates using age- and sex-adjusted logistic regression models within each of the 10 discovery studies (8720 cases and 55,152 controls). We performed an inverse variance weighted, fixed-effects meta-analysis of study-specific estimates to identify single-nucleotide polymorphisms that were associated independently with gallstone disease. Associations were replicated in 6489 cases and 62,797 controls. RESULTS: We observed independent associations for 2 single-nucleotide polymorphisms at the ABCG8 locus: rs11887534 (OR, 1.69; 95% confidence interval [CI], 1.54-1.86; P = 2.44 × 10(-60)) and rs4245791 (OR, 1.27; P = 1.90 × 10(-34)). We also identified and/or replicated associations for rs9843304 in TM4SF4 (OR, 1.12; 95% CI, 1.08-1.16; P = 6.09 × 10(-11)), rs2547231 in SULT2A1 (encodes a sulfoconjugation enzyme that acts on hydroxysteroids and cholesterol-derived sterol bile acids) (OR, 1.17; 95% CI, 1.12-1.21; P = 2.24 × 10(-10)), rs1260326 in glucokinase regulatory protein (OR, 1.12; 95% CI, 1.07-1.17; P = 2.55 × 10(-10)), and rs6471717 near CYP7A1 (encodes an enzyme that catalyzes conversion of cholesterol to primary bile acids) (OR, 1.11; 95% CI, 1.08-1.15; P = 8.84 × 10(-9)). Among individuals of African American and Hispanic American ancestry, rs11887534 and rs4245791 were associated positively with gallstone disease risk, whereas the association for the rs1260326 variant was inverse. CONCLUSIONS: In this large-scale GWAS of gallstone disease, we identified 4 loci in genes that have putative functions in cholesterol metabolism and transport, and sulfonylation of bile acids or hydroxysteroids.
Abnormal blood vessel growth in the retina is a hallmark of many retinal diseases, such as retinopathy of prematurity (ROP), proliferative diabetic retinopathy, and the wet form of age-related macular degeneration. In particular, ROP has been an important health concern for physicians since the advent of routine supplemental oxygen therapy for premature neonates more than 70 years ago. Since then, researchers have explored several animal models to better understand ROP and retinal vascular development. Of these models, the mouse model of oxygen-induced retinopathy (OIR) has become the most widely used, and has played a pivotal role in our understanding of retinal angiogenesis and ocular immunology, as well as in the development of groundbreaking therapeutics such as anti-vascular endothelial growth factor injections for wet age-related macular degeneration. Numerous refinements to the model have been made since its inception in the 1950s, and technological advancements have expanded the use of the model across multiple scientific fields. In this review, we explore the historical developments that have led to the mouse OIR model utilized today, essential concepts of OIR, limitations of the model, and a representative selection of key findings from OIR, with particular emphasis on current research progress.
The authors report their experience with orbital exenteration surgery at one academic institution over a 10-year period and review the literature. This retrospective cohort study monitored outcomes of all patients who underwent orbital exenteration surgery at Massachusetts Eye and Ear Infirmary between January 2003 and January 2013. Patients with no follow-up data or survival data were excluded from the study. The main outcome measures were surgical complications, disease status of surgical margins, need for adjuvant treatment, local recurrence, metastases and survival. 23 patients with malignancy and 2 with mucormycosis met inclusion criteria for the study. Surgical procedures included non-lid sparing total exenteration (44%), lid-sparing total exenteration (32%), non-lid sparing partial exenteration (8%) and lid-sparing partial exenteration (16%). 44% underwent additional extra-orbital procedures. Survival rates were 72% at 1 year, 48% at 3 years, and 37% at 5 years. Of patients with malignancies, 48% had clear margins after exenteration. There was no statistically significant difference in survival between patients with negative surgical margins compared to positive margins (p = 0.12). Mortality was highest in patients with melanoma (85.7%) and lowest in patients with non-squamous cell lid malignancies (0%). Our study suggests that the type of disease has a much greater impact on the survival of patients undergoing exenteration surgery than the type of exenteration surgery or the disease status of surgical margins. Patients with non-squamous cell lid malignancies and localized orbital disease have the best prognosis for tumor eradication from this radical and highly disfiguring surgery.
Scleritis is an inflammatory process of the sclera and adjacent tissues with a wide spectrum of clinical presentations and co-morbidities. Careful clinical history taking, detailed ocular examination, and appropriate investigation for likelihood of an underlying systemic disease are essential for diagnosis. Treatment can be quite challenging in some cases. Conventional therapy with corticosteroids and immunosuppressive agents may not be sufficient to control ocular inflammation in refractory patients. In such cases new therapeutic agents, which have a more targeted and sustained effect on the immune response, so-called biologic response modifiers, are being used. This review focuses on both diagnosis and therapeutic options including traditional and emerging therapies of non-infectious scleritis.
Mutations in NOTCH 3 are the cause of cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), a neurological disorder characterized by stroke, and vascular cognitive impairment and dementia. Loss of vascular smooth muscle cells (VSMC) and accumulation of granular osmiophilic material (GOM) deposits are hallmarks of CADASIL. There are no therapies for CADASIL and experimental endpoints to examine the preclinical efficacy of potential drugs are lacking. This study aims to use a mouse carrying the C455R mutation in Notch 3 to identify biomarkers associated with CADASIL. Mass spectrometry and antibody arrays were used to explore the aorta and blood proteomes of CADASIL mice, ELISA assays were utilized for biomarker validation, a ligand-dependent assay was applied to examine the relationship between Notch signaling and biomarker expression, and retinal histology was performed for quantification of VSMC loss in arteries. Two-hundred day-old mice with the C455R CADASIL mutation in Notch 3 mice display robust VSMC loss in retinal arteries and had increased plasma levels of collagen18α1/endostatin (col18α1) and high-temperature requirement A serine peptidase 1 (HTRA1) and reduced levels of Notch 3 extracellular domain (N3ECD), compared to control wild type mice. Measurements of plasma endostatin, HTRA1 and N3ECD, along with VSMC quantification in retinal arteries, may serve as surrogate endpoints for assessing efficacy in preclinical therapeutic studies of CADASIL using mice.
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.