Abstract
BackgroundGlobal concerns have been raised due to upward trend of Multi-drug Resistant (MDR) Pseudomonas aeruginosa reports in ocular infections. Our aim was to characterize the virulence determinants of MDR P. aeruginosa causing ocular infections.MethodsP. aeruginosa strains were isolated from 46 patients with conjunctivitis (2), endophthalmitis (11) and active keratitis (25) seen at our Institute, between 2016 and 2020. The isolates were identified by Vitek-2 and characterized based on growth kinetics, biofilm formation, motility, pyoverdine and pyocyanin production, phospholipase and catalase activity, urease production along with expression of exotoxins (exo-A, exo-U and exo-S) and correlated to its antibiotic profiles.ResultsOf the 46 P. aeruginosa isolates, 23 were MDR and were significantly (p = 0.03) associated with older (> 65) patients, along with higher production of pyoverdine (58.3%), pyocyanin (30.4%), phospholipase (91.6%) and protease (62.5%) activity, formed strong biofilms and exo-A (30.4%). No significant relation between motility, urease and catalase production with antibiotic susceptibility was observed. Heatmap and PCoA analysis confirmed this unique virulence profile associated with MDR-PA strains.ConclusionPhenotypic characteristics of P.aeruginosa might be responsible for increased colonization and antibiotic resistance observed in vivo and understanding these differences may lead to development of clinical guidelines for the management of MDR infections.
Highlights
Pseudomonas aeruginosa is the most common Gramnegative isolate causing vision-threatening ocular infections including conjunctivitis, keratitis, orbital cellulitis and endophthalmitis [1,2,3,4]
Clinical and microbiology records were retrospectively reviewed for patients who were evaluated at our institute and diagnosed with culture-confirmed infections [keratitis, endophthalmitis, cellulitis, conjunctivitis] due to P. aeruginosa
Out the 23 patients infected with susceptible isolates (S-PA) strains, 2 patients underwent evisceration who were diagnosed with post enucleation socket syndrome and microbial keratitis
Summary
Pseudomonas aeruginosa is the most common Gramnegative isolate causing vision-threatening ocular infections including conjunctivitis, keratitis, orbital cellulitis and endophthalmitis [1,2,3,4]. P. aeruginosa infections are very difficult to eradicate due to their intrinsic resistance to antibiotics [5], in addition, to various virulence factors like flagellin and lipopolysaccharide, as well as secreted products such as cytotoxins [6, 7], elastase [8, 9], alkaline protease [10, 11], protease IV [12], as well as its invasiveness and increased colonization has been reported to contribute to its pathogenicity [13,14,15,16]. Our aim was to characterize the virulence determinants of MDR P. aeruginosa causing ocular infections
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