Stenotrophomonas maltophilia: A Rare Cause of Paediatric Endogenous Endophthalmitis

Abstract

Endogenous endophthalmitis, accounting for between 0.1% and 4% of paediatric endophthalmitis cases, is a rare yet highly destructive infection of the eye [1]. Paediatric endogenous endophthalmitis has a higher incidence in developing countries, such as India, likely due to immunocompromised states secondary to nutritional deficiencies [2]. Stenotrophomonas maltophilia (S. maltophilia) is an emerging multi-resistant pathogen that can cause endophthalmitis, generally following trauma, intraocular lens implantation or intravitreal injections [3]. This series describes two paediatric cases of S. maltophilia endogenous endophthalmitis in healthy non-immunocompromised children.

In 2009, Das et al. described a case of S. maltophilia endogenous endophthalmitis in a healthy 30-year-old man with no identified portal of entry, no medical intervention, and no trauma [4]. More recently in 2024, Jain et al. described the first paediatric case of S. maltophilia endogenous endophthalmitis in a 10-year-old boy from India [2]. This patient had longstanding malnutrition and auricular discharge 2 weeks prior to symptoms. This is in contrast to our series, in whom both children were completely healthy and not immunocompromised.

S. maltophilia endogenous endophthalmitis typically presents with severe anterior and posterior segment inflammation [5]. Clinical features include hypopyon and vitreous exudates with significant choroidal thickening on B-scan ultrasonography [5]. In literature, initial presenting VA ranges from 6/95 (logMAR 0.06) to light perception, which is comparable to our case series (Case 1 = VA hand movements; Case 2 = VA 6/95). Case 1 had intermittent symptoms for a month prior to presentation, highlighting the challenge in detecting severe eye disease early in children as they may not articulate their symptoms accurately. In keeping with previous studies, our cases had no other source of infection [6]. This further highlights the diagnostic difficulties of endogenous endophthalmitis.

Empirical treatment for endophthalmitis is with broad-spectrum IVI antibiotics such as ceftazidime and vancomycin [5]. Pars plana vitrectomy may be indicated when there is minimal response on systemic treatment [5]. A key difference in management was steroid treatment, with Case 1 receiving only topical steroids, in contrast to Case 2 who had IV, oral and topical steroids. The use of steroids in endogenous endophthalmitis remains controversial and is highly dependent on host and pathogen factors [7]. Given its paucity, there is no literature analysing treatment options on visual outcomes in S. maltophilia endogenous endophthalmitis.

S. maltophilia is known to be a highly drug-resistant organism with variable antimicrobial sensitivities [6, 8]. Both children had S. maltophilia isolates that were resistant to ceftazidime but sensitive to trimethoprim-sulfamethoxazole. In 2010, Chen et al. described six cases of S. maltophilia endophthalmitis where isolates were susceptible to fluoroquinolones and trimethoprim-sulfamethoxazole, however, were resistant to ceftazidime and aminoglycosides [3]. In contrast, Chang et al. in 2013 published eight cases of S. maltophilia endophthalmitis after cataract surgery, with all isolates susceptible to ceftazidime, but all resistant to gentamicin and imipenem [8]. A 2016 study retrospectively analysing S. maltophilia isolates in a paediatric population reported that 91.3% were susceptible to trimethoprim-sulfamethoxazole [9]. Identifying the susceptibility pattern is therefore crucial for early targeted therapy, as the usual empirical intravitreal treatment (e.g., ceftazidime) may be ineffective against S. maltophilia.

Final visual outcome in S. maltophilia endogenous endophthalmitis is poor, with few patients achieving a final VA better than 6/60 (logMAR 1.0) [10]. Case 1 had a final VA worse than their initial VA, as a result of significant ocular sequelae and retinal detachment that required multiple surgical interventions. A retrospective study by Wang et al. reported a 14.8% incidence of retinal detachment after endophthalmitis with poor anatomical and functional outcomes [11]. Case 2 also had a large fibrin plaque in their vitreous however this resolved faster in comparison. This improvement was first noted after the completion of IV methylprednisolone, and continued to improve with the ongoing use of topical and oral steroids. Case 1 did not receive systemic steroids, but also presented with longer symptom duration and worse initial VA. Case 1 had a greater delay before a vitreous sample was obtained (36-h from presentation) in comparison to Case 2 (15-h from presentation). There is hesitancy amongst paediatric ophthalmologists in obtaining vitreous samples in children due to fear of malignant spread if an intraocular malignancy has not been excluded. Given the rarity of endogenous endophthalmitis, children with panuveitis are often assumed to have a systemic condition causing the inflammation, which may also contribute to intraocular sampling delay. This case series highlights different visual outcomes in two children, with distinctions in the timing of symptoms, timing of vitreous biopsy and use of systemic steroids. Early targeted control of the infection and inflammation associated with S. maltophilia endogenous endophthalmitis can reduce the risk of fibrotic membrane development, and should be reflected in guidelines.

Endorsement by the Children's Health Queensland Hospital and Health Service Human Research Ethics Committee (HREC) has been obtained.

Written informed consent was obtained from the patients for publication of this case series.

The authors declare no conflicts of interest.