Enterococcus faecalis Strains with Compromised CRISPR-Cas Defense Emerge under Antibiotic Selection for a CRISPR-Targeted Plasmid.

Enterococcus faecalis is a Gram-positive bacterium that natively colonizes the human gastrointestinal tract and opportunistically causes life-threatening infections. Multidrug-resistant (MDR) E. faecalis strains have emerged that are replete with mobile genetic elements (MGEs). Non-MDR E. faecalis strains frequently possess CRISPR-Cas systems, which reduce the frequency of MGE acquisition. We demonstrated in previous studies that E. faecalis populations can transiently maintain both a functional CRISPR-Cas system and a CRISPR-Cas target. In this study, we used serial passage and deep sequencing to analyze these populations. In the presence of antibiotic selection for the plasmid, mutants with compromised CRISPR-Cas defense and enhanced ability to acquire a second antibiotic resistance plasmid emerged. Conversely, in the absence of selection, the plasmid was lost from wild-type E. faecalis populations but not E. faecalis populations that lacked the cas9 gene. Our results indicate that E. faecalis CRISPR-Cas can become compromised under antibiotic selection, generating populations with enhanced abilities to undergo horizontal gene transfer. IMPORTANCE Enterococcus faecalis is a leading cause of hospital-acquired infections and disseminator of antibiotic resistance plasmids among Gram-positive bacteria. We have previously shown that E. faecalis strains with an active CRISPR-Cas system can prevent plasmid acquisition and thus limit the transmission of antibiotic resistance determinants. However, CRISPR-Cas is not a perfect barrier. In this study, we observed populations of E. faecalis with transient coexistence of CRISPR-Cas and one of its plasmid targets. Our experimental data demonstrate that antibiotic selection results in compromised E. faecalis CRISPR-Cas function, thereby facilitating the acquisition of additional resistance plasmids by E. faecalis.

Concentration-associated pathology of alkali burn in a mouse model using anterior segment optical coherence tomography with angiography.

Pathological features of alkali concentration-associated burn were studied using non-invasive anterior segment optical coherence tomography (AS-OCT) and OCT angiography (OCTA). Alkali burn was induced in C57BL/6J mice (n = 20) by placing filter paper soaked in 0.1, 0.25, 0.5, and 1 M NaOH for 30s on the right eye (left eye control). Longitudinal imaging was performed with AS-OCT/OCTA and fluorescein angiography over 14 days, after which eyes were enucleated at 7 and 14 days for histology and immunofluorescence. Concentration-associated corneal swelling was maximal at 0.5M, increasing linearly in a concentration-dependent fashion at 0.1, 0.25, and 0.5 M NaOH, to levels of 50%, 100%, and 175% of control, respectively. At 0.1M, corneal swelling and surface erosions were prominent, while at 0.25M, deep tissue damage, limbal neovascularization, and stromal haze were evident at 7 days. At 0.5M and 1M, severe exacerbation of the corneal swelling, angle closure, Descemet's membrane detachment, hyphema, and profuse central neovascularization were noted as early as day 3, which further progressed to inflammation, fibrosis, and opacity by day 7. We conclude that alkali concentration-dependent burn intensity biomarkers can be assessed by non-invasive AS-OCT/OCTA, distinguishing between mild, moderate, and severe ocular injury, with potential relevance toward clinical utilization in human eyes.

Localizing Thalamomesencephalic Afferent and Efferent Pupillary Defects.

ABSTRACT: A 42-year-old Algerian man presented for binocular oblique diplopia, hypersomnolence with drop attacks, bilateral hearing loss, and thoracic pain. He had a right thalamomesencephalic hemorrhage due to an underlying cavernous malformation treated with subtotal surgical resection. On neuro-ophthalmic examination, the patient had a left relative afferent pupillary defect and a right oculosympathetic efferent pupillary defect (i.e., Horner syndrome) in addition to other thalamomesencephalic eye and neurologic signs (right fourth nerve palsy, hearing loss, hemiparesis, and thalamic pain). Clinicians should recognize the localizing value of this unique constellation of mesencephalic afferent and efferent pupillary defects.

Petroclival Meningioma Presenting With an Ipsilateral Sixth Nerve Palsy and a Contralateral Homonymous Quadrantanopia: A Unique and Topographically Localizing Syndrome.

An 84-year-old woman reported onset of headaches, diplopia, and blurred vision. On examination, she was found to have a left sixth nerve palsy and an incongruous right homonymous hemianopia. Brain MRI demonstrated a left petroclival meningioma, causing this unusual combination of clinical findings. The patient was treated with radiation therapy and has remained stable over 4 years of follow-up.

Racial Disparities in Cataract Surgery Timeline and Intraocular Lens Selection: A Retrospective Study.

Purpose: There is a significant amount of literature focusing on racial inequities in utilization rates and intraoperative complications of cataract surgery. Unfortunately, little is known about racial disparities regarding the timeline of cataract surgery and intraocular lens (IOL) selection. This study investigated whether black patients have a different preoperative and postoperative cataract surgery timeline and IOL selection than white patients. Methods: A total of 10,235 patients (83.47% white) were retrospectively identified from a tertiary academic center who underwent cataract surgery between 2015 and 2022. Each patient's best corrected visual acuity (BCVA), slit lamp findings, and surgical timeline were recorded. IOL selection was categorized as standard or premium. Results: Black patients had significantly worse mean ± SD preoperative logMAR BCVA than white patients (0.47 ± 0.55 vs. 0.58 ± 0.70, respectively; P = 0.0117) and were significantly less likely to receive surgery within 120 days of referral (RR, 0.71 [95% confidence interval {CI}, 0.64-0.79]; P < 0.0001). White patients were 25%, 24%, and 29% less likely to follow-up than black patients at postoperative day 1, day 7, and day 30, respectively (P < 0.0001). White patients were 6.09 (95% CI, 3.49, 10.63) times more likely to receive a premium IOL compared to black patients (P < 0.0001). Conclusions: Black patients experienced more delays with receiving cataract surgery but are more adherent with postoperative follow-up. Black patients were far less likely to receive a premium IOL than white patients. Translational Relevance: Increased awareness of racial inequities in cataract surgery may improve the delivery of eye care to minority groups.

Vision Loss as Presenting Symptom in Testicular Cancer: A Morbid Case Report.

Testicular cancer is the most common malignancy in men 20-40 years old and most commonly metastasizes to the lung, liver, and brain. Choroidal metastasis from testicular cancer is exceedingly rare, and only few cases have been described in the literature. We report a patient who presented with painful unilateral vision loss as the initial presenting symptom of metastatic testicular germ cell tumor (GCT). A 22-year-old Latino man presented with a 3-week history of progressive central vision loss and dyschromatopsia, accompanied by intermittent, throbbing ocular, and periocular pain, in the left eye. Associated symptom was remarkable for abdominal pain. Examination of the left eye disclosed light perception vision and a large choroidal mass in the posterior pole involving the optic disk and the macula with associated hemorrhages. Neuroimaging showed a 2.1-cm lesion in the posterior globe of the left eye, and B-scan and A-scan ultrasonography findings were consistent with choroidal metastasis. Systemic workup revealed a mass in the left testicle with metastasis to the retroperitoneum, lungs, and liver. Biopsy of a retroperitoneal lymph node showed a GCT. Visual acuity worsened from light perception to no light perception 5 days following initial presentation. Several cycles of chemotherapy were completed, including salvage therapy; however, these treatments were unsuccessful. While vision loss due to choroidal metastasis as the initial presenting symptom of testicular cancer is rare, clinicians should consider metastatic testicular cancer in the differential diagnoses in patients with choroidal tumors, especially in young men.

CRISPR-Cas and Restriction-Modification Act Additively against Conjugative Antibiotic Resistance Plasmid Transfer in Enterococcus faecalis.

Enterococcus faecalis is an opportunistic pathogen and a leading cause of nosocomial infections. Conjugative pheromone-responsive plasmids are narrow-host-range mobile genetic elements (MGEs) that are rapid disseminators of antibiotic resistance in the faecalis species. Clustered regularly interspaced short palindromic repeat (CRISPR)-Cas and restriction-modification confer acquired and innate immunity, respectively, against MGE acquisition in bacteria. Most multidrug-resistant E. faecalis isolates lack CRISPR-Cas and possess an orphan locus lacking cas genes, CRISPR2, that is of unknown function. Little is known about restriction-modification defense in E. faecalis. Here, we explore the hypothesis that multidrug-resistant E. faecalis strains are immunocompromised. We assessed MGE acquisition by E. faecalis T11, a strain closely related to the multidrug-resistant hospital isolate V583 but which lacks the ~620 kb of horizontally acquired genome content that characterizes V583. T11 possesses the E. faecalis CRISPR3-cas locus and a predicted restriction-modification system, neither of which occurs in V583. We demonstrate that CRISPR-Cas and restriction-modification together confer a 4-log reduction in acquisition of the pheromone-responsive plasmid pAM714 in biofilm matings. Additionally, we show that the orphan CRISPR2 locus is functional for genome defense against another pheromone-responsive plasmid, pCF10, only in the presence of cas9 derived from the E. faecalis CRISPR1-cas locus, which most multidrug-resistant E. faecalis isolates lack. Overall, our work demonstrated that the loss of only two loci led to a dramatic reduction in genome defense against a clinically relevant MGE, highlighting the critical importance of the E. faecalis accessory genome in modulating horizontal gene transfer. Our results rationalize the development of antimicrobial strategies that capitalize upon the immunocompromised status of multidrug-resistant E. faecalis. IMPORTANCE Enterococcus faecalis is a bacterium that normally inhabits the gastrointestinal tracts of humans and other animals. Although these bacteria are members of our native gut flora, they can cause life-threatening infections in hospitalized patients. Antibiotic resistance genes appear to be readily shared among high-risk E. faecalis strains, and multidrug resistance in these bacteria limits treatment options for infections. Here, we find that CRISPR-Cas and restriction-modification systems, which function as adaptive and innate immune systems in bacteria, significantly impact the spread of antibiotic resistance genes in E. faecalis populations. The loss of these systems in high-risk E. faecalis suggests that they are immunocompromised, a tradeoff that allows them to readily acquire new genes and adapt to new antibiotics.