Molecular identification of Nocardia species causing endophthalmitis using multilocus sequence analysis (MLSA): a 10-year perspective

Microbiological Profile of Post-cataract Surgery Endophthalmitis with Usage of Prophylactic Intracameral Moxifloxacin

PURPOSE

To study the effect of prophylactic intracameral moxifloxacin (ICM) on microbiological profile and antimicrobial sensitivity of culture-proven postoperative endophthalmitis (POE).

METHODS

This study evaluated culture-proven POE diagnosed within 6 weeks of cataract surgery over two periods, period-1 (January 2010-March 2015) and period-2 (April 2015-December 2019), before and after introduction of prophylactic ICM, respectively.

RESULTS

In period-1, 100 cases of culture-positive POE were reported (1 in 4879, 0.02%), while 20 cases (1 in 24635, 0.004%) were reported in period-2 (5-fold reduction, p < .001). The cumulative culture positivity rate decreased from 27.6% to 17.1% (1.6-fold) . Coagulase-negative Staphylococci (CoNS) were significantly reduced (p = .005).

CONCLUSIONS

ICM reduced the incidence of culture-proven POE, CoNS in particular. In future, POE caused by rarer pathogens may become more prevalent due to reduction in the rate of commoner and more virulent pathogens with use of intracameral antibiotics. The moxifloxacin sensitivity of CONS did not show change with the use of ICM. Studies with larger population of POE will be more helpful to understand the trend better.

Periocular Infection With Nocardia nova Following Dacryocystorhinostomy With Silicone Stent Intubation

Nocardia species are aerobic, rod-shaped, Gram-positive bacteria that are ubiquitous throughout the environment. Nocardia nova has been reported as the second most prevalent Nocardia species. However, reports of ocular and periocular infection caused by this organism are rare. The authors present a case of a 58-year-old woman with a medical history of acquired nasolacrimal duct obstruction of the left eye who underwent a revision dacryocystorhinostomy with silicone stent intubation and developed a surgical site infection that was culture-positive for N. nova . Treatment consisted of removal of the silicone stent and a prolonged course of oral antibiotics, resulting in the patient's full recovery. This is the second reported case of postoperative periocular N. nova infection after dacryocystorhinostomy and silicone stent intubation.

Epidemiology of Nocardia Species at a Tertiary Hospital in Southern Taiwan, 2012 to 2020: MLSA Phylogeny and Antimicrobial Susceptibility

The identification and antimicrobial susceptibility of Nocardia spp. are essential for guiding antibiotic treatment. We investigated the species distribution and evaluated the antimicrobial susceptibility of Nocardia species collected in southern Taiwan from 2012 to 2020. A total of 77 Nocardia isolates were collected and identified to the species level using multi-locus sequence analysis (MLSA). The susceptibilities to 15 antibiotics for Nocardia isolates were determined by the broth microdilution method, and the MIC₅₀ and MIC₉₀ for each antibiotic against different species were analyzed. N. cyriacigeorgica was the leading isolate, accounting for 32.5% of all Nocardia isolates, and the prevalence of Nocardia isolates decreased in summer. All of the isolates were susceptible to trimethoprim/sulfamethoxazole, amikacin, and linezolid, whereas 90.9% were non-susceptible to cefepime and imipenem. The phylogenic tree by MLSA showed that the similarity between N. beijingensis and N. asiatica was as high as 99%, 73% between N. niigatensis and N. crassostreae, and 86% between N. cerradoensis and N. cyriacigeorgica. While trimethoprim/sulfamethoxazole, amikacin, and linezolid remained fully active against all of the Nocardia isolates tested, 90.9% of the isolates were non-susceptible to cefepime and imipenem.

Case Report: First Case of Endophthalmitis Caused by an Emerging Pathogen: Nocardia huaxiensis

Nocardia endophthalmitis is a relatively uncommon form of endophthalmitis seen in clinical patients. In general, Nocardia endophthalmitis tends to carry a poor prognosis. Here, we report a 3-year-old child who was admitted to the hospital due to a rupture of the left eye. The suturing and anterior chamber formation were performed immediately. Approximately, 16 days after the operation, massive whitish plump and tufted exudates gathered in the pupil area and at the bottom of the anterior chamber, and the child was diagnosed with endophthalmitis. The infection was initially considered to be caused by fungal pathogens for that the hyphae and spores were observed in the smear. However, the isolate obtained after 4 days of culturation was identified as actinomycetes using MALDI–TOF. We further classified it as Nocardia huaxiensis by next-generation sequencing (NGS) based on the MinION platform. Amikacin and sulfamethoxazole tablets were used to control the infection and the ocular inflammation subsided gradually. Intraocular lens (IOL) implantation is planned to be performed at an appropriate future time to improve his vision. Nocardia endophthalmitis is rare and usually caused by ocular trauma or surgery. In conclusion, Nocardia huaxiensis should be considered as an emerging pathogen and deserves more attention.

Role of Williamsia and Segniliparus in human infections with the approach taxonomy, cultivation, and identification methods

The genera Williamsia and Segniliparus are of aerobic actinomycetes and at the time of writing, they have 12 and 2 species, respectively. These genera cause various infections in humans. In this review, we surveyed their taxonomy, isolation, identification, as well as their role to cause human infections.

Post phacoemulsification wound infection by Nocardia cyriacigeorgica: a rare acid-fast organism

Tunnel infection is one of the most dreaded infections, post phacoemulsification. Most cases reported till now are caused by Gram-positive and Gram-negative bacteria or fungi and very few cases by the acid-fast organisms. Ocular infections by Nocardia usually have poor prognosis. Here, we report a case of tunnel infection, its management and microbiological identification of cause behind it, that is, Nocardia cyriacigeorgica a rare acid-fast microorganism.

Challenges in Post-cataract Surgery Nocardia Endophthalmitis: Management Strategies and Clinical Outcomes

PURPOSE

To describe the clinical and microbiological features, management strategies, outcomes, and challenges in post-cataract surgery nocardia endophthalmitis.

METHODS

We evaluated 28 eyes with culture-confirmed Nocardia endophthalmitis following cataract surgery. Data were collected regarding age, gender, clinical presentation, management modalities used, and final outcomes.

RESULTS

Mean age of the patients was 66.07 + -8.6 years. Four eyes (14.3%) underwent early pars plana core vitrectomy, while 18 eyes (64.3%) underwent tap/inject regimen followed by observation for 48 h, with or without a delayed vitrectomy. Thirteen eyes (46.4%) received amikacin treatment. Visual acuity (VA) improved from presentation in 9/28 (32.1%) eyes, worsened in 14/28 (50%) eyes, and showed no change in 5/28 eyes (17.9%).

CONCLUSIONS

We did not find any significant association between functional outcome and time of surgery or presenting VA. Additional amikacin may be considered if there is a strong suspicion of nocardia endophthalmitis, as it may help in achieving better anatomical outcomes.