Outbreak of Multidrug-resistant Pseudomonas Aeruginosa Endophthalmitis Due to Contaminated Trypan Blue Solution

Extensively drug-resistant Pseudomonas aeruginosa panophthalmitis from contaminated artificial tears

Pseudomonas aeruginosa is one of the common gram-negative organisms that cause severe invasive infections in different organ systems. P. aeruginosa has unique intrinsic mechanisms to develop antimicrobial resistance quickly, making it extremely difficult to treat. We report a case of extensively drug-resistant (XDR) P. aeruginosa panophthalmitis due to contaminated artificial tears. This report investigates the role of systemic and intravitreal antimicrobials, summarizes the resistance mechanisms of P. aeruginosa, and provides an overview on cefiderocol, a novel antimicrobial that targets multidrug-resistant (MDR) and XDR Gram-negative pathogens.

Molecular and microbiological evidence of bacterial contamination of intraocular lenses commonly used in canine cataract surgery

Inflammatory outcomes, including toxic anterior segment syndrome (TASS) and infectious endophthalmitis, are potentially painful, blinding complications following cataract surgery. In an in vitro pilot study, commercially available, sterile foldable intraocular lenses (IOLs) used during routine canine cataract surgery, and their packaging fluid were surveyed for the presence of bacterial DNA and/or viable (cultivable) bacteria. Swabs from IOLs and packaging fluid from three different veterinary manufacturers and three different production lots/manufacturer were collected for 16S ribosomal ribonucleic acid (rRNA) sequencing. Packaging fluid samples were collected for aerobic/capnophilic bacterial culture. Culture yielded one isolate, identified as Staphylococcus epidermidis. 16S rRNA sequencing revealed distinct brand-specific bacterial DNA profiles, conserved between IOLs and packaging fluid of all production lots within each manufacturer. The dominant taxonomy differentiating each manufacturer was annotated as Staphylococcus sp, and was a 100% match to S. epidermidis. Distinct mixtures of bacterial DNA are present and consistent in IOLs and packaging fluid depending on the manufacturer, and Staphylococcus is the dominant contributor to the bacterial DNA detected. Caralens products had a significantly lower amount of Staphylococcus spp. compared to Anvision and Dioptrix products.

Temporal Transcriptome Analysis Suggests Modulation of Key Pathways and Hub Genes in a Mice Model of Multi-Drug Resistant (MDR) Pseudomonas aeruginosa Endophthalmitis

PURPOSE

Increasing incidence of multidrug-resistant Pseudomonas aeruginosa (MDR-PA) causing endophthalmitis challenges our ability to manage this vision-threatening condition. In this study, temporal dynamics of immune response in a mouse model of MDR-PA endophthalmitis was investigated by whole transcriptome analysis.

METHODS

C57BL/6 mice were infected with MDR-PA and antibiotic susceptible (S-PA) clinical strains and disease severity were monitored at 6 and 24-h postinfection (p.i), following which eyeballs were enucleated. Microarray analysis was performed using SuperPrint G3 Mouse Gene Expression v2 chip and the differential gene expression analysis was performed with limma package in R (v4.0.0.)/Bioconductor (v3.11).

RESULTS

Histopathological analysis revealed a significant difference in retinal architecture and vitreous infiltrates at 6 and 24 h. In comparison to S-PA, MDR-PA revealed altered expression of 923 genes at 6 h and 2220 genes at 24 h. Further, 23 and 76% of these altered genes and its downstream interacting proteins showed time-specific expression (6 and 24 h respectively), indicating their association with disease progression. At 24 hours, MDR-PA induced endophthalmitis showed aberrant immune response with the enrichment inflammasome signalling, dysregulated ubiquitination, complement cascade, MMPs NF-κβ and IL-1 signalling.

CONCLUSION

The rapid development of transcriptional differences between the two-time points reveals that distinct genes contribute to disease severity. The results from this study highlighted a link between innate and adaptive immune responses and provided novel insights in the pathogenesis of MDR-PA endophthalmitis by extending the number of molecular determinants and functional pathways that underpin host-associated damage.

Prospective evaluation of the prevalence of conjunctival and intraocular bacteria in dogs undergoing phacoemulsification following a standardized aseptic preparation with 0.5% povidone iodine

PURPOSE

To evaluate bacterial contamination of conjunctiva and aqueous humor in dogs undergoing phacoemulsification following asepsis with 0.5% povidone iodine and determine the influence of intravenous antibiotics on outcome of contamination.

METHODS

Client-owned dogs were prospectively enrolled and randomly assigned to a control group, receiving 22 mg/kg intravenous cefazolin at induction prior to sampling, or experimental group receiving no antibiotic prior to sampling, masked to the surgeon. Dogs receiving antimicrobials in the pre-operative period were excluded. Asepsis was performed on all operated eyes using 0.5% iodine with minimum 3 min contact time at induction of anesthesia and repeated before surgery. A conjunctival swab and aqueous humor sample were collected prior to incision and following incision closure, respectively. Samples were submitted for aerobic and anaerobic bacterial culture and susceptibility.

RESULTS

Seventy-one eyes of 42 dogs were included. Median age was 9 years. Thirty-nine and 32/71 eyes received intravenous cefazolin and no antibiotic, respectively. Median procedure time was 40 min per eye. Conjunctival cultures were positive in 6 eyes (8.5%): Serratia marcescens (5 eyes) and Cutibacterium acnes (1 eye). Aqueous humor cultures were positive in 5 eyes (7.0%): S. marcescens (2 eyes), Pseudomonas aeruginosa (2 eyes), Staphylococcus pseudointermedius (1 eye). Prevalence of positive culture did not differ between groups (p = .74), order of eyes for bilateral procedures (p = .74) and diabetic status (p = 1).

CONCLUSIONS

Bacterial contamination of the conjunctiva and aqueous humor was present in 8.5% and 7.0% of dogs undergoing phacoemulsification after asepsis. Lack of IV cefazolin was not significantly associated with positive culture.

Transcriptomic and Histological Analysis of Exacerbated Immune Response in Multidrug-Resistant Pseudomonas aeruginosa in a Murine Model of Endophthalmitis

Multidrug-resistant (MDR) endophthalmitis is a serious threat to the whole spectrum of therapeutic procedures associated with the risk of managing and preventing vision loss. We have earlier shown the interplay of immune mediators in patients with MDR Pseudomonas aeruginosa (PA) endophthalmitis leading to worse outcome. Expanding on these findings, a murine model of endophthalmitis was developed to explore the effects of drug resistance on the pathogenesis by analyzing the temporal changes in retinal morphology along with its transcriptomic signatures. Clinical isolates of susceptible (S-PA) and multidrug-resistant PA (MDR-PA) were injected intravitreally in C57BL/6 mice followed by enucleation at 6 and 24 h time points postinfection. Disease progression and retinal changes were monitored by clinical and histological assessment and transcriptome analysis in a pair-wise manner. Histological assessment of MDR-PA eyeball revealed higher disease severity (p < 0.05), CD45+ cells (p = 0.007), MPO+ cells (p = 0.01), GFAP+ (p = 0.02), along with higher retinal cell death in mice infected with MDR-PA (p = 0.008). Temporal transcriptome analysis revealed differential expression of nearly 923 genes at 6 h p.i. and 2,220 genes at 24 h p.i. (FC ≥2, adjusted p-value <0.05). Pathway enrichment analysis identified differential regulation of chemokine- and cytokine-mediated, MAPK, and NF-кβ signaling pathways. In conclusion, rapid deterioration of retinal architecture and immune exacerbation was significantly associated with the MDR endophthalmitis, suggesting the need for immunomodulatory agents to strengthen host cell functions and support antibiotics to save the retinal structure from inevitable deterioration and restoration of the vision.

Outbreak of postoperative endophthalmitis caused by Pseudomonas aeruginosa: a case report and brief literature review

Endophthalmitis is the most serious complication of cataract surgery. A cluster of endophthalmitis is a devastating event for surgeons. Pseudomonas aeruginosa is the main causative pathogen of Gram-negative endophthalmitis, which can be suggestive of the occurrence of an outbreak.

Ten patients diagnosed with endophthalmitis after cataract surgery performed by one surgeon were analyzed in this study. At presentation, five patients had obvious clinical findings of endophthalmitis with visual acuity of light perception, two patients had poor light perception/no light perception of vision complicated by concomitant keratitis, and three patients had earlier signs of infection (e.g., a lower degree of anterior chamber and vitreous cells, better presenting visual acuity, and greater visibility of the fundus). Investigations revealed that the source of infection was growth of P. aeruginosa on the phaco probe. All of the surgeries had been performed by the same contaminated probe without sterilization between surgeries. This finding emphasizes the importance of strict adherence to sterility protocols during high-risk surgeries such as intraocular surgeries. Additionally, this report aims to emphasize to surgeons that negligence of simple but vital steps of sterility for any reason, such as limitations in time or equipment, can lead to catastrophic events.

Intraocular Povidone Iodine During Pars Plana Vitrectomy for Severe and Atypical Endophthalmitis

BACKGROUND AND OBJECTIVE

To describe the experience and clinical outcomes of povidone iodine (PI) infusion in the setting of pars plana vitrectomy for the treatment of endophthalmitis.

MATERIALS AND METHODS

This was a retrospective case series of 12 patients with clinical and/or culture evidence of endophthalmitis requiring pars plana vitrectomy with 0.025% PI used in vitreous irrigation solution during vitrectomy. The primary endpoint was clinical resolution of the infection. Secondary endpoints included visual recovery, need for repeat surgery, and ocular toxicity RESULTS: There were 11 eyes that showed clinical or culture evidence of resolution of infection postoperatively (91.7%); 10 eyes had improvement in vision postoperatively (83.3%). Overall uncorrected visual acuity improved from 20/5321 (2.43 ± 0.58 logMAR) to 20/375 (1.27 ± 1.05 logMAR) (P = .0003). No clinical evidence of ocular toxicity or unexplained vision loss due to PI was observed.

CONCLUSIONS

PI infusion during pars plana vitrectomy for endophthalmitis appears safe and led to excellent post-surgical results in a traditionally high-risk cohort. [Ophthalmic Surg Lasers Imaging Retina. 2021;52:485-490.].