Microbiological Profile and Clinical Characteristics of Bacterial Keratitis with Poor Visual Outcome

Purpose: To compare clinical characteristics between the poor visual outcome (PVO) and good visual outcome (GVO) groups in culture-proven bacterial keratitis.Methods: A total of 230 cases (44 and 186 eyes in the PVO and GVO groups, respectively) of culture-proven bacterial keratitis, treated between January 2007 and December 2020, were reviewed retrospectively. The PVO group included cases with the final best-corrected visual acuity (BCVA) of less than 0.1 and no improvement compared to the initial BCVA. The remaining cases were included in the GVO group. The microbiological profiles, epidemiology, predisposing factors, and clinical characteristics were compared between the PVO and GVO groups, and the risk factors for PVO were analyzed.Results: Staphylococcus spp. and Pseudomonas spp. were common isolates in both the PVO and GVO groups, with no significant differences in the distribution of isolates. There were no significant differences between the groups in terms of sex, seasonal distribution, corneal trauma, and prior topical steroid use, but contact lens wear was significantly less in the PVO group. Significant risk factors for PVO were age ≥60 years (Z = 4.22, two-proportion Z-test), central corneal lesions (Z = 3.80), epithelial defect size ≥5 mm² (Z = 3.74), prior ocular surgery (Z = 3.63), hypopyon (Z = 3.42), previous ocular surface disease (Z = 3.32), and diabetes (Z = 3.12).Conclusions: In patients with bacterial keratitis, PVO was associated with older age, severe initial corneal findings, previous ocular disease history, and diabetes, but not with the causative pathogen itself.

Characterisation of Bacteriophage vB_SmaM_Ps15 Infective to Stenotrophomonas maltophilia Clinical Ocular Isolates

Recent acknowledgment that multidrug resistant Stenotrophomonas maltophilia strains can cause severe infections has led to increasing global interest in addressing its pathogenicity. While being primarily associated with hospital-acquired respiratory tract infections, this bacterial species is also relevant to ophthalmology, particularly to contact lens-related diseases. In the current study, the capacity of Stenotrophomonas phage vB_SmaM_Ps15 to infect ocular S. maltophilia strains was investigated to explore its future potential as a phage therapeutic. The phage proved to be lytic to a range of clinical isolates collected in Australia from eye swabs, contact lenses and contact lens cases that had previously shown to be resistant to several antibiotics and multipurpose contact lenses disinfectant solutions. Morphological analysis by transmission electron microscopy placed the phage into the Myoviridae family. Its genome size was 161,350 bp with a G + C content of 54.2%, containing 276 putative protein-encoding genes and 24 tRNAs. A detailed comparative genomic analysis positioned vB_SmaM_Ps15 as a new species of the Menderavirus genus, which currently contains six very similar globally distributed members. It was confirmed as a virulent phage, free of known lysogenic and pathogenicity determinants, which supports its potential use for the treatment of S. maltophilia eye infections.