Moraxella keratitis: risk factors, presentation, and management

Moraxella Keratitis: A Case Series

OBJECTIVE

To report the ocular and systemic risk factors, clinical manifestations, and management outcomes of Moraxella keratitis.

METHODS

This retrospective study included patients with culture-proven Moraxella keratitis in South Texas between 2012 and 2018. Clinical data including demographics, ocular and systemic risk factors, clinical presentation, speciation, and treatment course were collected.

RESULTS

Fourteen eyes of 14 patients had culture-proven Moraxella keratitis which made up 8.1% of cases of culture-proven bacterial keratitis in the period studied. These included 10 men and 4 women with a mean age of 52.7±11.3 years. Ten patients (71.4%) had different ocular risk factors such as ocular trauma, corneal foreign body, contact lens use, preceding viral keratitis, neurotrophic cornea, and recent corneal transplant on topical steroids. Systemic risk factors included diabetes mellitus, systemic immunosuppressive therapy, cancer chemotherapy, and AIDS. There was no specific clinical manifestation. The size of stromal infiltration on initial presentation varied among the cases, with 71.4% stromal infiltrations of 4 mm or less. The patients were managed with fortified tobramycin, fortified vancomycin, and moxifloxacin eye drops. No eyes required surgical intervention during treatment for the active infection, except for one eye with pre-existing no light perception that was enucleated because of chronic pain.

CONCLUSIONS

Moraxella keratitis is a less frequent form of bacterial keratitis that appears more prevalent in patients with previous ocular conditions. Early diagnosis of this infection and medical treatment with a conventional corneal ulcer regimen can result in good clinical outcomes without the need for a surgical intervention.

Paradox of complex diversity: Challenges in the diagnosis and management of bacterial keratitis

Bacterial keratitis continues to be one of the leading causes of corneal blindness in the developed as well as the developing world, despite swift progress since the dawn of the "anti-biotic era". Although, we are expeditiously developing our understanding about the different causative organisms and associated pathology leading to keratitis, extensive gaps in knowledge continue to dampen the efforts for early and accurate diagnosis, and management in these patients, resulting in poor clinical outcomes. The ability of the causative bacteria to subdue the therapeutic challenge stems from their large genome encoding complex regulatory networks, variety of unique virulence factors, and rapid secretion of tissue damaging proteases and toxins. In this review article, we have provided an overview of the established classical diagnostic techniques and therapeutics for keratitis caused by various bacteria. We have extensively reported our recent in-roads through novel tools for accurate diagnosis of mono- and poly-bacterial corneal infections. Furthermore, we outlined the recent progress by our group and others in understanding the sub-cellular genomic changes that lead to antibiotic resistance in these organisms. Finally, we discussed in detail, the novel therapies and drug delivery systems in development for the efficacious management of bacterial keratitis.

Comparison of two methods for obtaining and transporting corneal samples in suspected infectious keratitis

BACKGROUND AND PURPOSE

The purpose of this study is to compare two alternative methods of collecting and transporting media for the diagnosis of corneal ulcers, as not all clinical settings have conventional culture materials and transport media available.

METHODS

In this open-label, prospective, comparative, and randomized study, patients with clinical suspicion of infectious keratitis with high risk of loss of vision had corneal specimens collected using two methods and transport media: Eswab scraping with Amies transport medium and 23-gauge needle scraping in BACTEC Peds broth. The order of each collection method was randomized. The samples were processed by standard methods, comparing the positivity frequencies for both by parametric and nonparametric tests, according to normality criteria.

RESULTS

Corneal infiltrates from 40 eyes of 40 patients were analyzed. Culture positivity rate was 50% for Eswab and 35% for 23-gauge needle (P=0.258). The overall growth rate of the two methods combined was not higher than with the swab alone. The results obtained with a swab were not influenced by the collection sequence (P=0.112); however, the positivity rate was significantly higher when the sample taken with the needle was performed first (P=0.046).

CONCLUSIONS

The single sample Eswab method of collection and transportation for the diagnosis of high risk corneal ulcers is a valid alternative and can be used in cases in which, for various reasons, there is no access to the full set of traditional culture materials.

Risk of Corneal Ulcer in Patients with Diabetes Mellitus: A Retrospective Large-Scale Cohort Study

This nationwide, retrospective, matched cohort study was designed to investigate the risk of corneal ulcer in patients with diabetes mellitus (DM). It included 238,701 patients with DM, recruited between 2003 and 2005 from the Longitudinal Cohort of Diabetes Patients database. The control group included the same number of age- and sex-matched non-DM patients selected from the Taiwan Longitudinal Health Insurance Database, 2000. The data of each patient were collected from the index date until December 2013. The incidence of corneal ulcer was compared between the two groups. In total, 2,549 patients with DM and 1,988 controls developed corneal ulcer during the follow-up period, resulting in an incidence rate for corneal ulcers that was 1.27 times (95% confidence interval [CI] = 1.20–1.35; P < 0.001) higher in patients with DM than in controls. After adjustment for potential confounders, including hyperlipidemia, hypertension, congestive heart failure, coronary artery disease, and chronic renal disease, patients with DM were 1.31 times (95% CI, 1.24–1.40; P < 0.05) more likely than the cohort to develop corneal ulcers. In conclusion, this study shows that DM increases the risk of corneal ulcer. Therefore, close collaboration between ophthalmologists and endocrinologists is important to ensure timely ophthalmology visits.

Moraxella species: infectious microbes identified by use of time-of-flight mass spectrometry

PURPOSE

To report the clinical manifestations, identification, antimicrobial susceptibilities, and treatment outcomes of ocular infections caused by Moraxella species.

STUDY DESIGN

Retrospective study.

PATIENTS AND METHODS

The medical records of all patients treated at the Departments of Ophthalmology of the Ogaki Municipal Hospital and the Gifu University Graduate School of Medicine for ocular infections caused by Moraxella species between January 2011 and June 2017 were examined. The stored Moraxella species isolated from ocular samples were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), molecular identification, and the biochemical properties.

RESULTS

Sixteen eyes of 16 patients were treated for Moraxella ocular infections. The patients' median age was 72 years. A predisposing systemic or ocular condition was identified in 15 of the patients. Nine of the patients developed keratitis; four, conjunctivitis; and three, blebitis. M lacunata (6 eyes), M catarrhalis (6), M nonliquefaciens (3), and M osloensis (1) were identified by MALDI-TOF MS. All isolates were sensitive to levofloxacin, tobramycin, ceftazidime, ceftriaxone, and cefazolin. Twelve patients with keratitis or blebitis were treated with various topical antimicrobial combinations, and systemic antibiotics were used in 10 of the 12 patients. The mean time for the complete closure of the epithelial defects with keratitis was 24 days. The visual outcomes after treatment were favorable except in 1 keratitis patient who underwent enucleation.

CONCLUSIONS

The use of duo-therapy with a combination of fluoroquinolone and cefmenoxime should be considered in cases nonresponsive to monotherapy, such as keratitis and bleb-associated infections. MALDI-TOF MS is useful for the identification of Moraxella to the species level.

Moraxella Keratitis: Analysis of Risk Factors, Clinical Characteristics, Management, and Treatment Outcomes

PURPOSE

To analyze the risk factors, clinical characteristics, management, and treatment outcomes of culture-proven cases of Moraxella keratitis at our center.

DESIGN

Retrospective observational case series.

METHODS

Thirty-nine culture-proven cases of Moraxella keratitis (39 eyes) diagnosed and treated between January 2003 and April 2018 at the University of Pittsburgh Medical Center were identified and retrospectively reviewed for ocular and systemic risk factors, treatment modalities, and outcomes, as well as for antimicrobial sensitivity and resistance data.

RESULTS

The mean age of the 39 patients was 63.0 (range 4-95 years) with median follow-up time of 170 days. Thirty-four of 39 patients (87.2%) had an ocular risk factor, the most common of which were blepharitis in 12 (30.8%), dry eyes in 12 (30.8%), and history of ocular surgery in 9 (23.1%). History of diabetes mellitus was found in 8 patients (20.5%). Thirty-six of 39 patients (92.3%) received a fluoroquinolone (92.3%) and 30 of 39 (76.7%) received topical fortified antibiotics. Resistance to fluoroquinolones, gentamicin, and tobramycin was seen in 1 patient each, respectively. Four patients (10.3%) required tarsorrhaphy, 6 patients (15.4%) required penetrating keratoplasty, and 1 patient required enucleation. Of the 35 patients for whom visual acuity information was available, 19 (54.3%) were count fingers or worse at most recent follow-up.

CONCLUSIONS

Ocular risk factors, especially poor ocular surface, were identified in the vast majority of patients with Moraxella keratitis. Moraxella isolates in our study were susceptible to fluoroquinolones and aminoglycosides. Many patients required surgical intervention and the final visual acuity was often poor.

Moraxella atlantae keratitis presenting with an infectious ring ulcer

Purpose

Moraxella atlantae is a rare pathogen. Keratitis from this organism has never been specifically reported or described. In this report we provide the first clinical description and photograph of Moraxella atlantae infectious keratitis.

Observations

A 41 year-old man presented with a three day history of left eye pain. He was found to have a corneal ring ulcer and infiltrate from which Moraxella atlantae was cultured. The patient was successfully treated with intensive topical gatifloxacin (0.5%) and fortified tobramycin (1.5%); oral doxycycline was added to reduce corneal thinning. The patient's infection resolved with a residual scar and final best corrected visual acuity of 20/200 OS.

Conclusions and importance

Moraxella atlantae can present as a ring-shaped infectious corneal infiltrate and ulcer. Ring infiltrates have been observed with other microorganisms, including several other gram negative bacteria and classically, acanthamoeba. Frequently presumed to be purely immunologic, corneal ring infiltrates can have a number of other etiologies, including infectious and toxic. There are different types of immunologic rings as well, making differentiation of corneal rings sometimes difficult for the ophthalmologic generalist and subspecialist alike. In this paper we discuss characteristics of various corneal ring infiltrates, along with their immune pathophysiology. Infectious rings are distinguished from immunologic Wessely rings.

Clinical Characteristics and Bacteriological Profile of Moraxella Keratitis

PURPOSE

Moraxella species are rare causative pathogens of severe sight-threatening keratitis. The aim of this study was to analyze the clinical presentation, predisposing risk factors, in vitro antimicrobial susceptibility, and treatment associated with Moraxella keratitis.

METHODS

We retrospectively reviewed 30 culture-proven cases of Moraxella keratitis from multiple centers in Japan.

RESULTS

The mean age of the patients was 58.4 ± 23.4 years. The most common ocular conditions were contact lens wearing (5 patients, 16.7%) and trauma (3 patients, 10.0%). Seven patients had diabetes mellitus. Sixteen patients exhibited hypopyon in association with the corneal focus. Ring-shaped infiltration was found in 9 patients (30.0%), and irregular or amoebic-shaped infiltration was observed in 13 patients (43.3%). Eight patients (26.7%) showed small round infiltrates. All Moraxella isolates were sensitive to fluoroquinolones and aminoglycosides. All were treated with a combination ophthalmic solution containing a fluoroquinolone, tobramycin, and cefmenoxime. Although no patients developed corneal perforation, the response to treatment was slow in all cases; the mean treatment period was 41.9 days.

CONCLUSIONS

In Japan, Moraxella keratitis occurs in patients with contact lens wear, trauma, and diabetes mellitus. It presents as a small, round, ring-shaped, irregularly shaped, or amoebic-shaped focus. Moraxella species exhibit good susceptibility to fluoroquinolones and aminoglycosides. Because the treatment response may be very slow, these agents should be continued for a long period of time.