Stenotrophomonas maltophilia endophthalmitis caused by surgical equipment contamination: an emerging nosocomial infection

Infection prevention and control factors associated with post-cataract surgery endophthalmitis - a review of the literature from 2010 - 2023

Patients undergoing cataract surgery are at risk of post-cataract surgery endophthalmitis (PCSE), a sight-threatening complication. Cataract surgery is a relatively straightforward and quick procedure often performed under local anaesthetic. It is therefore simple to scale up to reduce the currently long waiting times, but it is important to maintain patient safety when considering high throughput surgery. This literature review aimed to identify appropriate infection prevention and control (IPC) measures to support increased throughput of cataract surgery in Scotland. Database searches were conducted using Medline and Embase from 2010 to 2023. Further hand-searching was also performed. The organisms associated with PCSE and IPC factors relevant to PCSE were analyzed. A range of microorganisms was associated with PCSE, where outbreak reports were most associated with Gram-negative bacteria and fungi, whereas retrospective chart reviews were most associated with Gram-positive bacteria. IPC risk factors identified were related to the built environment and issues with sterilization. Specifically, the sources of outbreaks included failures in the ventilation system, as well as contaminated ophthalmic solutions, surgical instruments, and medications. The factors identified in this review should be considered when implementing high throughput cataract surgery to ensure that patient safety is maintained.

Antimicrobial Susceptibility, Minimum Inhibitory Concentrations, and Clinical Profiles of Stenotrophomonas maltophilia Endophthalmitis

Stenotrophomonas maltophilia has been reported in various ocular infections, including keratitis, conjunctivitis, preseptal cellulitis, and endophthalmitis, all of which may lead to vision loss. However, the S. maltophilia strain is resistant to a wide variety of antibiotics, including penicillins, third-generation cephalosporins, aminoglycosides, and imipenem. In this study, we retrospectively reviewed the clinical characteristics, antibiotic susceptibility, antimicrobial minimum inhibitory concentrations (MICs), and visual outcomes for S. maltophilia endophthalmitis. The data of 9 patients with positive S. maltophilia cultures in a tertiary referral center from 2010 to 2019 were reviewed. Cataract surgery (n  =  8, 89%) was the most common etiology, followed by intravitreal injection (n  =  1, 11%). S. maltophilia’s susceptibility to levofloxacin and moxifloxacin was observed in 6 cases (67%). Seven isolates were resistant to sulfamethoxazole-trimethoprim (78%). The MIC₉₀ for S. maltophilia was 256, 256, 256, 8, 12, 12, 12, and 8 μg/mL for amikacin, cefuroxime, ceftazidime, tigecycline, sulfamethoxazole-trimethoprim, levofloxacin, galtifloxacin, and moxifloxacin, respectively. Final visual acuity was 20/200 or better in 5 patients (56%). Fluoroquinolones and tigecycline exhibited low antibiotic MIC₉₀. Therefore, the results suggest that fluoroquinolones can be used as first-line antibiotics for S. maltophilia endophthalmitis.

Advances in the Microbiology of Stenotrophomonas maltophilia

Stenotrophomonas maltophilia is an opportunistic pathogen of significant concern to susceptible patient populations. This pathogen can cause nosocomial and community-acquired respiratory and bloodstream infections and various other infections in humans. Sources include water, plant rhizospheres, animals, and foods. Studies of the genetic heterogeneity of S. maltophilia strains have identified several new genogroups and suggested adaptation of this pathogen to its habitats. The mechanisms used by S. maltophilia during pathogenesis continue to be uncovered and explored. S. maltophilia virulence factors include use of motility, biofilm formation, iron acquisition mechanisms, outer membrane components, protein secretion systems, extracellular enzymes, and antimicrobial resistance mechanisms. S. maltophilia is intrinsically drug resistant to an array of different antibiotics and uses a broad arsenal to protect itself against antimicrobials. Surveillance studies have recorded increases in drug resistance for S. maltophilia, prompting new strategies to be developed against this opportunist. The interactions of this environmental bacterium with other microorganisms are being elucidated. S. maltophilia and its products have applications in biotechnology, including agriculture, biocontrol, and bioremediation.

Intraocular lipopolysaccharide examination for early diagnosis of Stenotrophomonas maltophilia endophthalmitis: a case report

This report describes the presence of Stenotrophomonas maltophilia endophthalmitis after phacoemulsification in a 66-year-old woman. The patient presented with ocular redness and pain, as well as hypopyon in the anterior chamber and reduction of visual acuity to hand motion. Intraocular fluid examination revealed a lipopolysaccharide level of >2.5, which suggested bacterial endophthalmitis. The patient was promptly treated with intravitreal ceftazidime 2 mg and vancomycin 1 mg, as well as intravenous infusion of cefuroxime 750 mg, all administered simultaneously at 12-hour intervals. She also received topical levofloxacin eyedrops, once per hour. Subsequently, pathology culture confirmed the presence of the Gram-negative bacillus, S. maltophilia. The presence of lipopolysaccharide in intraocular fluid is an important early indicator of bacterial endophthalmitis, which can provide guidance for clinical treatment.

Clinical and Optical Coherence Tomography Angiographic Features in Patients with Postcataract Stenotrophomonas maltophilia Endophthalmitis

Purpose

To report the clinical presentations and optical coherence tomography (OCT) angiographic features of patients with postcataract surgery endophthalmitis due to Stenotrophomonas maltophilia. Methods. A retrospective observational study of 4 patients who developed S. maltophilia endophthalmitis after cataract surgery. Pars plana vitrectomy (PPV) was performed to control the infection. Patients were followed up for six months. Complete ophthalmological examination results were collected before and after PPV.

Results

Patients' response to PPV therapy was excellent and the infection was cured in all cases. OCTA showed that, at the one-month follow-up, the vascular density (VD) and perfusion density (PD) in the superficial capillary plexus (SCP) were significantly lower than those in healthy collateral eyes. As time went on, the SCP-VD and SCP-PD values gradually improved.

Conclusions

With early PPV, the infection caused by S. maltophilia can be cured. OCTA provides a quantitative noninvasive assessment to evaluate the severity and prognosis of patients with S. maltophilia endophthalmitis.

Stenotrophomonas maltophilia: An emerging entity for cluster endophthalmitis

PURPOSE

This was a study of acute cluster endophthalmitis along with clinical features, culture results, and visual outcomes of 10 eyes of 10 patients after intravitreal injection of Avastin (bevacizumab) in one sitting from a single vial.

METHODS

Retrospective review of intravitreal injection of 1.25 mg/0.05 ml bevacizumab that was given to 10 eyes of 10 patients on the same day from a freshly opened vial. All patients manifested with endophthalmitis the next day. Vitreous tap for direct smear and culture was done. Intravitreal antibiotics and steroids were injected and appropriate treatment begun. The injection vial of the same batch was sent for VITEKTM identification and antimicrobial susceptibility of isolates.

RESULTS

Endophthalmitis presented within 24 h of intravitreal injection. There was a remarkable absence of posterior pupillary synechia. Two cases were culture-positive (20%), showing pseudomonoid growth. The vial of the same batch revealed a pseudomonoid bacilli Stenotrophomonas maltophilia using VITEKTM, which was resistant to multiple drugs. Hence, the contaminated vial was identified as the source of infection in our case. Among 10 patients, two underwent pars plana vitrectomy. Visual acuity returned to preendophthalmitis levels in 9/10 eyes after 1 month. One patient was lost to follow-up. Late complications included retinal detachment in one case and neovascular glaucoma in another.

CONCLUSION

Early recognition and treatment are key factors in improving outcomes. Causative etiology could be microbial contamination of the drug vial. S. maltophilia should be considered a pathogenic organism of postintravitreal endophthalmitis.