Effect of Pseudomonas aeruginosa Concentration in Experimental Contact Lens--Related Microbial Keratitis

Lawin-Brüssel, Christiane A.; Refojo, M.F.; Leong, Fee‐Lai; Hanninen, Laila A.; Kenyon, K R

doi:10.1097/00003226-199301000-00003

Cited by 22 publications

(11 citation statements)

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“…A variety of methods have been described in the literature for introducing bacteria or fungi to experimental (in vivo, in vitro or ex vivo) corneas. These include the use of bacterial/fungal-inoculated contact lenses [ 20 , 21 ], blotting paper and ethylene glycol tetraacetic acid (EGTA) [ 7 ], and mechanical removal of the epithelial surface [ 22 , 23 ]. However, the most commonly described methods are corneal scratch [ 24 , 25 ] and intrastromal injection [ 26 , 27 ].…”

Section: Discussionmentioning

confidence: 99%

Ex vivo rabbit and human corneas as models for bacterial and fungal keratitis

Pinnock

Shivshetty

Roy

et al. 2016

Graefes Arch Clin Exp Ophthalmol

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PurposeIn the study of microbial keratitis, in vivo animal models often require a large number of animals, and in vitro monolayer cell culture does not maintain the three-dimensional structure of the tissues or cell-to-cell communication of in vivo models. Here, we propose reproducible ex vivo models of single- and dual-infection keratitis as an alternative to in vivo and in vitro models.MethodsExcised rabbit and human corneoscleral rims maintained in organ culture were infected using 108 cells of Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans or Fusarium solani. The infection was introduced by wounding with a scalpel and exposing corneas to the microbial suspension or by intrastromal injection. Post-inoculation, corneas were maintained for 24 and 48 h at 37 °C. After incubation, corneas were either homogenised to determine colony-forming units (CFU)/cornea or processed for histological examination using routine staining methods. Single- and mixed-species infections were compared.ResultsWe observed a significant increase in CFU after 48 h compared to 24 h with S. aureus and P. aeruginosa. However, no such increase was observed in corneas infected with C. albicans or F. solani. The injection method yielded an approximately two- to 100-fold increase (p < 0.05) in the majority of organisms from infected corneas. Histology of the scalpel-wounded and injection models indicated extensive infiltration of P. aeruginosa throughout the entire cornea, with less infiltration observed for S. aureus, C. albicans and F. solani. The models also supported dual infections.ConclusionsBoth scalpel wounding and injection methods are suitable for inducing infection of ex vivo rabbit and human cornea models. These simple and reproducible models will be useful as an alternative to in vitro and in vivo models for investigating the detection and treatment of microbial keratitis, particularly when this might be due to two infective organisms.

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Section: Discussionmentioning

confidence: 99%

Ex vivo rabbit and human corneas as models for bacterial and fungal keratitis

Pinnock

Shivshetty

Roy

et al. 2016

Graefes Arch Clin Exp Ophthalmol

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“…PMN are responsible for the development of corneal marginal infiltrates and are a well-established feature of the pathologic changes seen in diffuse lamellar keratitis (5, 12; S. P. Holland, R. Mathias, D. W. Morck, and S. Slade, submitted for publication) (Sands of the Sahara keratitis) following laser-assisted in situ keratomileusis. Corneal marginal infiltrates are known to occur as a result of direct bacterial infection or following contact of the ocular surface with contaminated medical devices, including contact lenses (7,16,17), and Sands of the Sahara keratitis (5, 12; S. P. Holland, R. Mathias, D. W. Morck, and S. Slade, submitted for publication) is suspected to be caused by LPS contamination of laser surgery sites. Findings from the present study demonstrate that LPS alone may recruit PMN at sites of epithelial injury and hence may contribute to these syndromes.…”

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confidence: 99%

Lipopolysaccharide Entry in the Damaged Cornea and Specific Uptake by Polymorphonuclear Neutrophils

Schultz

Buret²,

Olson

et al. 2000

Infect Immun

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Bacterial lipopolysaccharide (LPS) is an important agent of induction of ocular pathology following corneal injury or wearing of contaminated contact lenses. The mechanism of LPS uptake through the corneal epithelium is unclear, and the role played by inflammatory cells in this phenomenon has not been previously assessed. Fluorescein isothiocyanate-labeled LPS from Escherichia coli was deposited onto the abraded corneas of New Zealand White rabbits. Epifluorescence microscopy of living excised corneas revealed diffuse LPS staining in the epithelial and stromal layers only in the vicinity of the abrasion. In addition, specific cellular uptake of LPS was suggested by fluorescence staining of cells along the abrasion site. In a second series of experiments, an anti-CD18 polyclonal antibody was used to block infiltration of polymorphonuclear neutrophils (PMN) into the cornea. In these experiments, a diffuse distribution of fluorescent LPS was still observed along the abrasion, but the specific cellular uptake was abolished. The findings indicate that LPS enters the cornea via diffuse penetration at sites of injury and that specific cellular uptake of LPS occurs within the cornea via PMN which have migrated into the damaged tissue.

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“…The beta-Poisson model has been reported as the best fit dose-response model for P. aeruginosa [49] with the end response of corneal ulceration. The optimized model parameters values were used in this study that corresponded to the model parameters values obtained from pooled data from experiments 297 and 298 [50] for P. aeruginosa in white rabbit [49]. The values of the parameters are shown in Table 3.…”

Section: Dose-response Modelingmentioning

confidence: 99%

Reverse QMRA as a Decision Support Tool: Setting Acceptable Concentration Limits for Pseudomonas aeruginosa and Naegleria fowleri

Rasheduzzaman

Singh

Haas

et al. 2019

Water

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Opportunistic premise plumbing pathogens such as Pseudomonas aeruginosa and Naegleria fowleri are a growing concern in building water systems because of their potential risks to human health. The aim of this study was to determine the critical concentrations of P. aeruginosa and N. fowleri in water that are associated with meaningful public health risks. To determine these concentrations, a reverse quantitative microbial risk assessment (QMRA) was conducted. Environmental concentrations of P. aeruginosa and N. fowleri corresponding to the risk target of one micro-disability-adjusted life year (DALY) per person per year and 10−4 annual risks of illness were calculated for several applicable exposure scenarios. To calculate the concentration of P. aeruginosa, cleaning contact lenses with potentially contaminated tap water in the absence of an appropriate cleaning solution was considered. For N. fowleri, two exposure scenarios, recreational exposure (swimming) and nasal cleansing (via the use of a neti pot™ or similar device) were considered. The highest critical concentration for P. aeruginosa was found to be 33 CFU/L with a 95% confidence interval of (2.0, 118) for the drop exposure scenario using the 10−4 annual risk target. For N. fowleri, based on the DALY approach, critical concentrations were 0.000030 N. fowleri/L for swimming and 0.00000060 N. fowleri/L for neti pot™ use scenario. Considering heat inactivation, the critical concentration limits for P. aeruginosa using the DALY approach and the 10−4 annual risk target approach were found to be 0.55 CFU/L and 55 CFU/L, respectively. For N. fowleri, the 10−4 annual risk target approach resulted in 0.022 N. fowleri/L and the DALY approach resulted in 0.00000064 N. fowleri/L for the neti pot™ scenario. For P. aeruginosa, N50 (the median infective dose) and alpha (α) contributed the most and contact rates the least to the variability and uncertainty of the estimates for all the scenarios. For N. fowleri, N50 and contact rates contributed the most and α the least to the variability and uncertainty to calculate the concentrations for all the scenarios. The QMRA framework implemented in this research can be used to incorporate more information regarding opportunistic pathogens to inform management decisions, and to prioritize the best interventions regarding estimated reduction in infections caused by opportunistic pathogens.

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Effect of Pseudomonas aeruginosa Concentration in Experimental Contact Lens--Related Microbial Keratitis

Cited by 22 publications

References 0 publications

Ex vivo rabbit and human corneas as models for bacterial and fungal keratitis

Ex vivo rabbit and human corneas as models for bacterial and fungal keratitis

Lipopolysaccharide Entry in the Damaged Cornea and Specific Uptake by Polymorphonuclear Neutrophils

Reverse QMRA as a Decision Support Tool: Setting Acceptable Concentration Limits for Pseudomonas aeruginosa and Naegleria fowleri

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