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R. M. Stewart, C. Winstanley, T. J. Neal, S. Tuft, S. B. Kaye, Microbiology Ophthalmic Group; Genotypic and Phenotypic Characteristics of Pseudomonas Aeruginosa Keratitis Isolates and Their Relationship to Clinical Outcome and Antimicrobial Sensitivity. Invest. Ophthalmol. Vis. Sci. 2008;49(13):2479.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate in cases of Pseudomonas aeruginosa associated keratitis, pathogenicity-related variable genes and islands, and genetic relationships between isolates in terms of clinical outcome and antimicrobial minimum inhibitory concentrations (MIC).
Ulcer and scar size, antimicrobial used and healing (HT) and treatment (TT) times, were recorded for 183 cases of Pseudomonas aeruginosa associated keratitis. MICs were determined for ciprofloxacin, ofloxacin, ceftazidine, cefuroxime, amikacin, chloramphenicol, gentamicin, penicillin G, vancomycin and teicoplanin. A subset of 63 isolates were characterised using a novel genomotyping and pathotyping system (CLONDIAG): a PCR-based biotin-labelling step was performed on cell suspensions, labelled probes hybridised to a tube array (containing 77 oligonucleotide markers) and a signal profile detected using a specific tube reader. Genetic relationships between strains were analysed by single linkage studies and the presence of pathogenicity-related variable genes and islands compared to ulcer size, HT, TT and MICs.
Mean TT and HT were 26.17 (STDV 28.71) and 17.82 (28.74) days, respectively. Mean ulcer and scar size were 3.04 x 3.38 and 2.21 x 1.90mm, with a scar to ulcer ratio of 0.83 (0.42). Mean HT and TT to ulcer size were 4.11 (4.31) and 8.07 (8.25) days/mm2. Ciprofloxacin had the lowest MIC 0.26 (0.65), followed by ofloxacin 0.95 (1.23) and gentamicin 2.94 (19.11) µg/ml. There was great variability in the pattern of pathogenicity-related variable genes and islands. Single linkage studies showed some genetically similar subsets but no evidence of a common clone. There was no significant correlation between any variable genes or islands and HT or TT/ulcer size, or MICs.
No common clone of Pseudomonas aeruginosa was identified. There was no correlation between the presence of specific pathogenicity-related variable genes or islands and clinical outcome or antimicrobial sensitivity.
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