Brevundimonas vesicularis keratitis after laser in situ keratomileusis

In the eye of the ophthalmologist: the corneal microbiome in microbial keratitis

PURPOSE

To describe the bacterial findings by a targeted sequencing approach from corneal samples of patients with microbial keratitis and factors influencing culture outcome of indirectly inoculated corneal specimen.

METHODS

Prospective inclusion of patients fulfilling predefined criteria of microbial keratitis. Samples from the corneal lesion were collected and dispensed in liquid transport medium, from which both culture and targeted amplification and sequencing of the V3-V4 region of the 16S rRNA gene were carried out. Additional standard corneal culture from the corneal lesions was also performed. Factors influencing culture outcome of indirectly inoculated corneal samples were identified by a multivariate regression model incorporating quantitative data from sequencing.

RESULTS

Among the 94 included patients with microbial keratitis, contact lens wear (n = 69; 73%) was the most common risk factor. Contact lens wearers displayed significant differences in the bacterial community composition of the corneal lesion compared to no lens wearers, with higher abundance of Staphylococcus spp., Corynebacterium spp., and Stenotrophomonas maltophilia. Targeted sequencing detected a potential corneal pathogen in the highest proportional abundance among 9 of the 24 (38%) culture-negative patients with microbial keratitis. Age, bacterial density in the sample, and prior antibiotic treatment significantly influenced culture outcome of indirectly inoculated corneal samples.

CONCLUSION

Targeted sequencing may provide insights on pathogens in both culture negative episodes of microbial keratitis and among subgroups of patients with microbial keratitis as well as factors influencing culture outcome of indirectly inoculated corneal samples.

Shotgun metagenomic sequencing in culture negative microbial keratitis

PURPOSE

To evaluate the microbiota of culture negative Corneal Impression Membrane (CIM) microbial keratitis samples with the use of shotgun metagenomics analysis.

METHODS

DNA of microbial keratitis samples were collected with CIM and extracted using the MasterPure™ Complete DNA and RNA Purification Kit (Epicentre). DNA was fragmented by sonication into fragments of 300 to 400 base pairs (bp) using Bioruptor® (Diagenode, Belgium) and then used as a template for library preparation. DNA libraries were sequenced on Illumina® HiSeq2500. The resulting reads were quality controlled, trimmed and mapped against the human reference genome. The unmapped reads were taxonomically classified using the Kraken software.

RESULTS

18 microbial keratitis samples were included in the study. Brevundimonas diminuta was found in 5 samples while 6 samples showed the presence of viral infections. Cutibacterium acnes, Staphylococcus aureus, Moraxella lacunata and Pseudomonas alcaligenes were also identified as the presumed putative cause of the infection in 7 samples.

CONCLUSIONS

Shotgun sequencing can be used as a diagnostic tool in microbial keratitis samples. This diagnostic method expands the available tests to diagnose eye infections and could be clinically significant in culture negative samples.

Brevundimonas Species Keratitis in a Patient without Underlying Disease

Purpose: To report a case of keratitis caused by Brevundimonas diminuta/vesicularis.Case summary: A 20-year-old man presented with decreased visual acuity and glare in his right eye from 2 days earlier. At the first visit, slit lamp examination revealed a 1.5 × 1.5 mm2-sized stromal infiltration, an edematous cornea and endothelial deposits in the center of the right eye. Microbiological examinations were performed from corneal scrapings. Treatment was started with topical eye drops (fortified cefazolin, fortified tobramycin) as empirical antibiotics. After several days, the cultures revealed Brevundimonas diminuta/vesicularis. After treatment with empirical antibiotic eye drops, the symptoms and visual acuity improved.Conclusions: We report a case of infectious keratitis caused by Brevundimonas diminuta/vesicularis, which has never previously been reported in the Republic of Korea.

Brevundimonas spp: Emerging global opportunistic pathogens

Non-fermenting Gram-negative bacteria are problematic in clinical locations, being one of the most prevalent causes of nosocomial infections. Many of these non-fermenting Gram-negative bacteria are opportunistic pathogens that affect patients that are suffering with underlying medical conditions and diseases. Brevundimonas spp., in particular Brevundimonas diminuta and Brevundimonas vesicularis, are a genus of non-fermenting Gram-negative bacteria considered of minor clinical importance. Forty-nine separate instances of infection relating to Brevundimonas spp were found in the scientific literature along with two pseudo-infections. The majority of these instances were infection with Brevundimonas vesicularis (thirty-five cases – 71%). The major condition associated with Brevundimonas spp infection was bacteraemia with seventeen individual cases/outbreaks (35%). This review identified forty-nine examples of Brevundimonas spp. infections have been discussed in the literature. These findings indicate that infection review programs should consider investigation of possible Brevundimonas spp outbreaks if these bacteria are clinically isolated in more than one patient.

A premature neonate with early-onset neonatal sepsis owing to Brevundimonas vesicularis complicated by persistent meningitis and lymphadenopathy

Human infection by Brevundimonas vesicularis is very rare, especially in children. A 29-week-old neonate is reported who developed early neonatal sepsis owing to B. vesicularis complicated by persistent meningitis and lymphadenopathy. B. vesicularis may be an emerging pathogen in neonatal infection.

Liver abscess caused by Brevundimonas vesicularis in an immunocompetent patient

Invasive infections caused by Brevundimonas vesicularis are very rare in humans. We experienced an unusual case of liver abscess due to B. vesicularis in an immunocompetent young male. The patient was successfully treated by liver abscess drainage and with antimicrobial therapy of ceftriaxone followed by ampicillin/sulbactam. The organism found in the aspiration culture of the abscess material was initially reported, by using a VITEK 2 system, as Sphingomonas paucimobilis. However, later, B. vesicularis was confirmed as the true pathogen through 16S rRNA gene sequencing. To our knowledge, this is the first case of liver abscess caused by B. vesicularis.

Brevundimonas vesicularis bacteremia resistant to trimethoprim-sulfamethoxazole and ceftazidime in a tertiary hospital in southern Taiwan

BACKGROUND

Over the past 20 years, Brevundimonas vesicularis has rarely been reported as a pathogen causing human infection. The clinical manifestations of B. vesicularis bacteremia and its susceptibility to antibiotics has not been characterized.

METHODS

A retrospective study was conducted between 2006 and 2009 in a tertiary-care hospital in southern Taiwan.

RESULTS

A total of 22 cases of B. vesicularis bacteremia were identified during the study with 86% being community-acquired primary bloodstream infections. Of the 22 patients, 15 (68%) presented with fever, fewer comorbidities, shorter hospital stays, lower mean creatinine levels (1.10 mg/dL vs. 1.74 mg/dL), lower aspartate aminotransferase levels (29.1 IU/L vs. 79.0 IU/L), and lower alanine aminotransferase levels (16.4 IU/L vs. 67.0 IU/L) when compared to afebrile patients. Among the bacterial isolates, 90.9% were susceptible to cefpirome, imipenem and piperacillin/tazobactam while 86.4% were susceptible to gentamicin, amikacin and ciprofloxacin. However, 63.6% of the bacterial isolates were susceptible to ceftazidime, and only 59.1% were susceptible to trimethoprim-sulfamethoxazole (TMP-SMX). The 30-day mortality rate from all causes was 4.5%.

CONCLUSION

B. vesicularis is able to cause community-acquired and low-mortality primary bloodstream infections. The resistance of B. vesicularis to trimethoprim-sulfamethoxazole and ceftazidime limits the choice of available antibiotics for treatment.

Brevundimonas diminuta keratitis

PURPOSE

To report the first documented case of keratitis secondary to the gram-negative bacillus Brevundimonas diminuta.

METHODS

A 66-year-old woman with an ocular history of bilateral soft contact lens wear presented with a large, 6×9-mm, culture-positive Pseudomonas aeruginosa-induced corneal ulcer. After weeks of therapy, she developed secondary keratitis. Repeat cultures grew a rare, gram-negative bacillus, B. diminuta.

RESULTS

Targeted therapy followed by adjustments based on repeat bacterial cultures with sensitivities resulted in slow resolution of the ulcer. After months of therapy, the cornea recovered leaving only a minimal corneal scar. Visual acuity improved from a low of Hand Motions to a final 20/40.

CONCLUSIONS

This is the first reported case of ocular infection with B. diminuta. This case demonstrates the need to be aware of potential rare secondary infections in corneas compromised by an initial infection and to adjust pharmacotherapy based on sensitivities and clinical signs.