Antibiotic therapy in post-operative endophthalmitis

ALTERNATIVE INTRAVITREAL ANTIBIOTICS: A Systematic Review for Consideration in Recalcitrant or Resistant Endophthalmitis

PURPOSE

To organize, categorize, and create a quick reference guide for the use of intravitreal antibiotic alternatives to the standard combination of vancomycin and ceftazidime for the treatment of endophthalmitis.

METHODS

A systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines. The authors searched for all available information regarding intravitreal antibiotics in the last 21 years. Manuscripts were selected according to relevance, level of information, and the available data regarding intravitreal dose, potential adverse effects, bacterial coverage, and relevant pharmacokinetic information.

RESULTS

The authors included 164 of 1810 manuscripts. The antibiotics were classified according to their class into fluoroquinolones, cephalosporins, glycopeptide and lipopeptide, penicillins and beta-lactams, tetracyclines, and miscellaneous. The authors also included information regarding intravitreal adjuvants for the treatment of endophthalmitis and one ocular antiseptic.

CONCLUSION

The treatment of infectious endophthalmitis is a therapeutic challenge. The current review summarizes the properties of possible intravitreal antibiotic alternatives that should be considered in cases of suboptimal response to initial treatment.

Bacillus S-Layer-Mediated Innate Interactions During Endophthalmitis

Bacillus endophthalmitis is a severe intraocular infection. Hallmarks of Bacillus endophthalmitis include robust inflammation and rapid loss of vision. We reported that the absence of Bacillus surface layer protein (SLP) significantly blunted endophthalmitis severity. Here, we further investigated SLP in the context of Bacillus-retinal cell interactions and innate immune pathways to explore the mechanisms by which SLP contributes to intraocular inflammation. We compared phenotypes of Wild-type (WT) and SLP deficient (ΔslpA) Bacillus thuringiensis by analyzing bacterial adherence to and phagocytosis by human retinal Muller cells and phagocytosis by mouse neutrophils. Innate immune receptor activation by the Bacillus envelope and purified SLP was analyzed using TLR2/4 reporter cell lines. A synthetic TLR2/4 inhibitor was used as a control for this receptor activation. To induce endophthalmitis, mouse eyes were injected intravitreally with 100 CFU WT or ΔslpA B. thuringiensis. A group of WT infected mice was treated intravitreally with a TLR2/4 inhibitor at 4 h postinfection. At 10 h postinfection, infected eyes were analyzed for viable bacteria, inflammation, and retinal function. We observed that B. thuringiensis SLPs contributed to retinal Muller cell adherence, and protected this pathogen from Muller cell- and neutrophil-mediated phagocytosis. We found that B. thuringiensis envelope activated TLR2 and, surprisingly, TLR4, suggesting the presence of a surface-associated TLR4 agonist in Bacillus. Further investigation showed that purified SLP from B. thuringiensis activated TLR4, as well as TLR2 in vitro. Growth of WT B. thuringiensis was significantly higher and caused greater inflammation in untreated eyes than in eyes treated with the TLR2/4 inhibitor. Retinal function analysis also showed greater retention of A-wave and B-wave function in infected eyes treated with the TLR2/4 inhibitor. The TLR2/4 inhibitor was not antibacterial in vitro, and did not cause inflammation when injected into uninfected eyes. Taken together, these results suggest a potential role for Bacillus SLP in host-bacterial interactions, as well as in endophthalmitis pathogenesis via TLR2- and TLR4-mediated pathways.

Precipitate Formation after Subconjunctival Administration of Ceftazidime and Vancomycin

This is a case report of precipitate formation after the administration of subconjunctival antibiotics after uneventful intravitreal antibiotic administration in a patient with endophthalmitis.