Academic literature on the topic 'Microbial keratitis'

Objective: To find out the incidence ofmicrobial keratitis in patients with red eyes. Design: randomized prospective study. Period: 07 months ranging from1st Jun 2001 to 31 Dec 2001. Place of study: Eye Department, Military H st ospital, Rawalpindi. Results: Out of 857patients with red eye 32 cases were found to have Microbial Keratitis (3%). Conclusion: Preventive aspects of ocularinfection should be taught to the people, like, proper washing of eyes, wearing of protective glasses. Patients comingwith ophthalmic problems, i.e., red eye, photophobia, irritation and watering to the general practitioner should bereferred as soon as possible to the ophthalmology department.

Background: In microbial keratitis, infection of the cornea can threaten vision through permanent corneal scarring and even perforation resulting in the loss of the eye. A literature review was conducted by Karsten, Watson and Foster (2012) to determine the spectrum of microbial keratitis. Since this publication, there have been over 2600 articles published investigating the causative pathogens of microbial keratitis. Objective: To determine the current spectrum of possible pathogens implicated in microbial keratitis relative to the 2012 study. Methods: An exhaustive literature review was conducted of all the peer-reviewed articles reporting on microbial pathogens implicated in keratitis. Databases including MEDLINE, EMBASE, Scopus and Web of Science were searched utilising their entire year limits (1950-2019). Results: Six-hundred and eighty-eight species representing 271 genera from 145 families were implicated in microbial keratitis. Fungal pathogens, though less frequent than bacteria, demonstrated the greatest diversity with 393 species from 169 genera that were found to cause microbial keratitis. There were 254 species of bacteria from 82 genera, 27 species of amoeba from 11 genera, and 14 species of virus from 9 genera, which were also identified as pathogens of microbial keratitis. Conclusion: The spectrum of pathogens implicated in microbial keratitis is extremely diverse. Bacteria were most commonly encountered and in comparison, to the review published in 2012, further 456 pathogens have been identified as causative pathogens of microbial keratitis. Therefore, the current review provides an important update on the potential spectrum of microbes, to assist clinicians in the diagnosis and treatment of microbial keratitis.

This thesis describes the impact of contact lens-related microbial keratitis in terms of incidence and severity. Disease outcome is defined by visual outcome, costs to the healthcare system, costs to the individual and duration of disease. A successful 12-month surveillance study was conducted of the populations of Australia and New Zealand to detect all cases of contact lens-related microbial keratitis. A random telephone survey of 32,000 households in Australia and 7,500 in New Zealand accurately determined the level of use of various contact lenses in the community. The impact of new contact lens types: silicone hydrogels and daily disposables were investigated. Increased risk persisted in overnight wear with silicone hydrogel materials. Microbial keratitis associated with silicone hydrogel materials had slightly shorter disease duration however other factors had a stronger influence on severity. Rigid gas permeable and frequent replacement soft lenses when used for daily wear constitute the lowest risk. Cost analysis was developed in a hospital case series of microbial keratitis. This analysis was applied in the surveillance study including cases managed in the private health care sector. Disease duration and associated costs are novel indices of severity for contact lens-related disease. The most dramatic effects on disease severity were seen with the type of organism involved. Keratitis attributed to environmental organisms (Gram-negative bacteria, Acanthamoeba, fungi and Nocardia species) were 10x more likely to cause loss of visual acuity, had longer duration of symptoms and incurred higher costs. Importantly, delays in receiving treatment increased disease duration and associated costs. Greater awareness of the need for specialist healthcare is indicated amongst health care providers and contact lens wearers. The hypothesis that overnight wear in silicone hydrogel lenses would not increase the risk of infection has been disproven. This information is of value to practitioners who are responsible for informing contact lens wearers about the risk of contact lens-related infections and should be weighed against the benefits of continuous wear. The identification of factors which contribute to the outcomes of disease will be used in education campaigns amongst health care providers and contact lens wearers to minimise the impact of disease.

Background: Microbial keratitis (MK) is a major cause of blindness worldwide. Few studies have assessed the HRT3 in vivo confocal microscope (IVCM) in the diagnosis or management of MK. This PhD aimed to investigate these questions and was based in a high incidence setting for MK: Aravind Eye Hospital, Madurai, India. Methods: A prospective observational study of 252 severe MK patients was conducted with follow-up at days 7, 14 and 21 post-enrolment. Quantitative PCR of corneal swabs obtained at presentation validated transcriptome results. IVCM images were evaluated in this cohort for diagnostic accuracy, and ability to monitor outcome. Results: For fungal detection, HRT3 IVCM had a high sensitivity (85.7%; 95% CI: 82.2%– 88.6%) and specificity (81.4%; 95% CI: 76.0%–85.9%). For Acanthamoeba, the sensitivity was 88.2% (95% CI: 76.2%–94.6%) and specificity was 98.2% (95% CI: 94.9%–99.3%). Mean fungal branching angle in IVCM images was not significantly different for Fusarium sp. (59.7°; 95% CI: 57.7°–61.8°) versus Aspergillus sp. (63.3°; 95% CI: 60.8°–65.8°; p=0.07). At presentation, anterior corneal IVCM morphology associated with BK included bullae (OR 9.99, 95% CI: 3.11–32.06, p < 0.001), and in FK a honeycomb distribution of inflammatory cells (OR 2.74, 95%CI: 1.01–7.40, p=0.047). Poor outcomes in FK were associated with stellate interconnected cellular processes with no visible nuclei (OR 2.28, 95% CI: 1.03-5.06, p=0.043) in baseline IVCM images, and fungal filaments (OR 6.48, 95% CI:2.50-16.78, p < 0.001) or inflammatory cells in a honeycomb distribution (OR 5.24, 95% CI: 1.44-19.06, p=0.012) in final visit images. Conclusions: HRT3 IVCM can yield a high diagnostic accuracy. Fungal branching angle in IVCM images does not differentiate between Fusarium and Aspergillus keratitis. IVCM image morphologies may be associated with causative organism or clinical outcome in MK.

Microbial keratitis is the most serious, and only potentially blinding complication of contact lens wear. To further understand and reduce the risk of this disease, incidence rates and risk factors have been estimated in numerous studies. Since these studies were conducted, new lens types have been introduced designed to reduce the risk of infection. It was hypothesised that the issues of contact lens related hypoxia and poor lens hygiene could be addressed by the introduction of silicone hydrogel and daily disposable lenses respectively. This thesis describes the incidence of and risk factors for contact lens related microbial keratitis in Australia and New Zealand. The incidence of infection was determined by capturing all cases of contact lens related presumed microbial keratitis in a 12-month surveillance study, and by estimating the number of lens wearers using a population-based phone survey. Characteristics of the cases and controls were compared to estimate risk factors. In Australia, rates of infection with daily and overnight wear of hydrogel lenses were similar to previously published reports (1.9 [95%CI]:1.8-2.0] and 19.5 [95%CI:14.6-29.5] per 10,000 wearers respectively). Compared to the incidence of infection with hydrogel lenses, silicone hydrogel lenses had a higher rate in daily wear (11.9 [95%CI: 10.0-14.6]), and a similar rate in extended wear (19.5 [95%CI:14.6-29.5]). Daily disposable lenses had a similar rate of infection to daily wear of hydrogel lenses (2.0 [95%CI:1.7-2.4]), but appeared to reduce the incidence of severe or vision loss keratitis (0.5 [95%CI: 0.5-0.6] and 0.0 [95%CI: 0.0-0.0] respectively). Conducting the study in New Zealand confirmed the increase in incidence for overnight use of lenses, irrespective of lens type. Comparison of the incidence rates in New Zealand and Australia show that the rates in the two countries are comparable, bar an unexplained lower rate of infection for extended wear of soft hydrogel lenses in New Zealand. Risk factors for infection were overnight use of lenses, from occasional overnight to extended wear use, poor lens case hygiene, smoking, high socio-economic status and less than 6 months experience in current lens type. Amongst daily wearers, Internet or mail order purchasing of lenses was also associated with a higher risk of infection. This study is unique in terms of the study design and sample size, and the wide scope of risk factors considered. The determination of these incidence rates of infection and identification of risk factors is of extreme value to lens wearers and lens care practitioners around the world, particularly as the strongest and most prevalent risk factors are modifiable.

Microbial keratitis (MK) is a leading cause of blindness in the developing world. Pseudomonas aeruginosa (PA) is the most common pathogen isolated from contact lens related MK, and is usually associated with significant visual complications. The intact corneal epithelium forms a strong barrier to bacterial penetration into deeper tissue, and only when bacteria reach the stroma, through a breach in the epithelium, does a typical ulcer develop, with stromal suppuration and necrosis. Since corneal fibroblasts are one of the most prominent cellular components in the stroma, they probably have an important role in the pathogenesis of corneal ulceration. The aim of this study was to establish an in vitro model of PA microbial keratitis in order to examine the microbiological, biochemical and ultrastructural changes associated with live infection of primary human corneal fibroblasts (hCF) with PA, and to assess the role of these cells in the initiation and progression of the pathogenesis of the disease. Human corneal fibroblast monolayers were infected with bacteria, and bacterial association was assessed at 3, 6 and 9h, bacterial invasion was assessed at 9h and cytokine profiles were assessed at 9 and 24 h post challenge. Host cell death was assessed at 9h using a lactate dehydrogenase assay (LDH). Gentamicin was added at 3h to eliminate all extra cellular bacteria and limit pathogen induced effects, and bacterial replication and survival and its effect on host cell viability were assessed. Induction of cytokine and matrix metalloproteinase (MMP) production by hCF in response to PA infection was assessed by a sandwich immunoassay and a gelatine zymography. To examine the interactions of PA with the cornea as an organ, donor corneal buttons remaining after DSEK were incubated in a medium inoculated with PA for 3-9h, then processed for scanning and transmission electron microscopy. Scanning and Transmission Electron Micrographs (SEM/TEM) of bacterial association and invasion of corneal cells were acquired and showed that bacteria associated to superficial epithelial cells but only invaded and colonized the stroma in the presence of a mechanical breach to the epithelial basement membrane. PAO1 bacteria caused monolayer disruption within 24h with all infective doses (101-108 CFU/mL). PAO1 associated to hCF in a dose- and time-dependant manner utilizing type IV pilus and flagella. Bacterial internalization was detected by the gentamicin assay, which also demonstrated the ability of PAO1 to survive and replicate within the fibroblasts, and was dependant on the SRC tyrosine kinase and the actin microfilament system, where internalisation was diminished when these systems were inhibited. Cytotoxicity was observed by 9h post challenge, and was reliant on bacterial type III secretion system and flagella, where mutant bacterial strains induced less cytotoxicity. The more virulent PA14 bacteria induced more cytotoxicity than PAO1. The presence of intracellular bacteria did not affect cell viability in the presence of gentamicin. In response to PAO1 infection, hCF produced the pro-inflammatory IL-1β and GM-CSF, although GM-CSF seems to be released later than IL-1β as shown by protecting the cells with gentamicin 3h post challenge. Infection with PA14 caused an earlier and more potent cytokine production than PAO1, reflecting the pattern of cytotoxicity. Bacterial components did not have a significant effect on cytokine production by corneal fibroblasts. Cytokine production was partly reliant on bacterial type III secretion system and flagella, and wild type PA14 strains induced an earlier and more potent IL-1β production by infected corneal fibroblasts. Gelatine zymography showed that hCF produce specific MMPs in response to live PA challenge for 24h, and these MMPs were not released in response to treatment with individual bacterial components and virulence factors. Bacteria alone produced alkaline protease, a bacterial MMP. Sandwich immunoassays showed that MMP-1, MMP-2, MMP-3 and MMP-9 were produced by infected fibroblasts to a level similar to uninfected cells. Gentamicin protected cells produced more MMPs than unprotected cells.

[Truncated abstract] The cornea plays a major role in the refraction of light and thus the maintenance of its transparency is critical for optimal vision. Infection or trauma can initiate a host inflammatory response, which can cause edema of the collagenous stroma. This tissue edema compromises vision by disrupting the regular arrangement of the corneal stromal lamellae, whose organization is critical to its refractive properties. Until recently, it was the accepted dogma that the cornea was an immune privileged tissue owing in part to its avascular nature and paucity of resident macrophages and dendritic cells (DCs) in the central region of the cornea. However, recent studies have identified heterogenous populations of macrophages and DCs in both the corneal stroma and epithelium. Despite the recognition of the existence of these cells in the cornea, very little is known about their biological role. The overall purpose of the experiments described in this thesis is to characterise corneal macrophages and DCs in homeostatic conditions and investigate their role in the initiation of inflammatory responses to bacterial ligands that induce corneal inflammation and contribute to the severity and resolution of bacterial keratitis. Experiments described in this thesis utilized a range of transgenic, knock-out and bone marrow (BM) chimeric mice to address the immunological function and characterization of BM-derived cells in the mouse cornea. Of particular importance was the use of Cx3cr1 transgenic mice, which contain an enhanced green fluorescent protein (eGFP) encoding cassette knocked into the Cx3cr1 gene that disrupts its expression but facilitates GFP expression under the control of the Cx3cr1 promoter. ... This highlights a novel functional role for corneal BM-derived cells in the recognition and initiation of inflammatory responses to LPS. Finally, a novel observation of a potential mechanism by which DC in the cornea communicate with neighbouring DCs via fine membrane extensions was identified in both chimeric and wild-type mice. These membrane nanotubes, found exclusively on MHC class II+ cells in the corneal stroma, significantly increased in density in the central cornea under inflammatory conditions, suggesting a role for these cell protrusions in the immune response. These data represent the first ever description of nanotubes in vivo, the only previous evidence of their presence being in vitro studies. In summary, the data presented in this thesis supports a role for Cx3cr1 in the homing of DCs to the normal corneal epithelium and also suggests that Cx3cr1-deficiency may influence the ability of corneal macrophages and DCs to respond to bacteria. In addition, the thesis supports a role for resident corneal macrophages and DCs in the initiation of immune responses following challenge with LPS, which is possibly supported by a newly discovered system of membrane nanotubes. A greater understanding of the biology of the resident corneal immune cells could lead to the development of potential therapies aimed at targeting macrophages and DCs as a means of regulating potentially harmful inflammatory responses in the cornea.

碩士
國立臺灣大學
臨床醫學研究所
93
Background Corneal infection is a leading cause of ocular morbidity and blindness worldwide. Effective topical therapy, using fortified antimicrobials selected based on the results of diagnostic corneal smears and cultures, is essential for management of patients with microbial keratitis. The spectrum of micro-organisms responsible for microbial keratitis varies in different geographical locations. Variations such as these probably occur worldwide, however, relatively little is known about the situation in Taiwan, where the climate is subtropical. Understanding the spectrum of microorganisms and clinical characters of microbial keratitis in our environment is the key for successful treatment. The antibiotic drug susceptibility changes with different locations and different time according to literature reviews. The spectrum of microorganisms and drugs available differ with different countries. There was no such report in Taiwan, and it is necessary for us to establish the work. Some pathogens have special treatment modality. Some pathogens are susceptible to special antibiotics, and the relationship may vary with time. Some pathogens have poor response to medical treatment, and surgery is inevitable. These pathogens reflect the weak side of our modern pharmacology. It is necessary to establish the spectrum of microorganism of microbial keratitis and the drug susceptibility in Taiwan. The work will improve the prognosis of microbial keratitis in this local area and will be helpful in the drug susceptible monitoring in the world. Study aims: 1. To analyze the clinical characters and spectrums of microorganisms of microbial keratitis in national Taiwan university hospital in proceeding 12 years. 2. To analyze the antibiotics susceptibility of bacterial keratitis in national Taiwan university hospital in proceeding 12 years and try to find the best regiment for bacterial keratitis. Materials and Methods: Medical records were reviewed for patients with clinical diagnosis of keratitis who were hospitalized at the National Taiwan University Hospital (NTUH), one of the largest tertiary medical centers in northern Taiwan, from January 1992 to December 2003. These patients were identified through a computerized diagnostic code search for all inpatients that had keratitis as the discharging diagnosis. Medial records were carefully examined and patients with diagnosis of microbial keratitis were included. All data were typed in Microsoft Excel software and were transported to STATA software. P value <0.05 was considered statistically significant. For the purpose of comparison, the patients were divided into two groups stratified according to diagnosis during the six-year periods, January 1992 to December 1997, and, January 1997 to December 2003. Results and Discussions Five hundred seventy-three eyes in 547 patients were included in the final evaluation. Patients included 272 males (49.7%) and 275 females (50.3%), aged from seven months to 96 years (mean age 40.8±22.2). The mean age of microbial keratitis in recent 6 years was younger than in previous 6 years（39.1 vs. 43.8, p=0.013）. The patients in 16-30 years group increased significantly in recent 6 years（30.3% vs. 45.8%, p<0.001）. The most common predisposing factor for microbial keratitis was contact-lens wear (45.4%), followed by ocular trauma (22.6%), chronic ocular and systemic disorders （17.1%） and recent ocular surgery （15%）. Identification of pathogens from the smears of corneal scrapings was achieved for 270 eyes (49.3%), and included Gram-negative (48.9%) and Gram-positive organisms (24.4%), fungi (16.7%), acid-fast bacilli (8.5%), and Acanthamoeba species (1.5%). Cultures of corneal scrapings were available for 550 eyes, with pathogens recovered for 260 (positive culture rate 48.9%). Pseudomonas species were the most commonly isolated organisms (38.17%), followed by fungi (13.4%), staphylococcus species (8.4%), nontuberculous mycobacteria (7.7%), Streptococcus species (7.4%), and Acanthamoeba species (4.3%). The prevalence of atypical mycobacterial keratitis decreased significantly from 12.8% and 5.5% during the second half of this study (1997-2001, p=0.026). Contact lens wear was highly related to Pseudomonas infection （odds ratio=4.26, p=0.007） as compared with referent other predisposing factors . Recent ocular surgery predisposing factor was related to atypical microbacterial infection （odds ratio=5.84, p=0.008）. Contact lens wear was reversely related to Streptococcus infection （odds ratio=0.12, p=0.01） . Ocular trauma was related to fungal infection （odds ratio=5.94, p=0.009） . Medical treatment was successful for 421 eyes (73.5%), while 152 eyes (26.5%) required additional surgical treatment, including lamellar keratectomy (n=35), penetrating keratoplasty (n=93), enucleation (n=11), and evisceration (n=13). The percentage of medical treatment increased significantly in recent 6 years（64.7% vs. 79.6%, p<0.001）. The percentage of patient receiving penetrating keratoplasty decreased significantly in recent 6 years（23.8% vs. 10.9%, p<0.001）. There was no antibiotic susceptibility change in Staphylococcus, Streptococcus, Pseudomonas and atypical mycobacterium in recent 6 years. In Gram-negative organisms the susceptibility of fortified antibiotics, cefazolin and gentamicin combination, was 79.4% during 1994 to 2003. The susceptibility of ciprofloxacin was 98.5%. Ciprofloxacin was better in dealing with Gram-negative organisms（p<0.001）. In all bacterial pathogens the susceptibility of cefazolin and gentamicin combination was 79.7%. The susceptibility of cefazolin and ciprofloxacin combination was 89.3%（p=0.008）. In the relationship between special pathogen and clinical characters, we found that Pseudomonas was related to a large corneal erosion（OR=1.03）, shorter time between symptom onset to definite treatment（OR=0.9）, and medical treatment only（OR=0.31） as compared with referent other pathogens. Atypical mycobacterium was related to longer time between symptom onset to definite treatment（OR=1.04）and surgical treatment indicated（OR=29.61）. Fungal keratitis was related to old age（OR=1.03）and surgical treatment indicated（OR=2.65）. In surgically treated microbial keratitis we found that the patients were older（OR=1.04）, have longer time between symptom onset to definite treatment（OR=1.02）. In predisposing factors contact lens wear was reversely related to surgical treatment（OR=0.25）as compared with other predisposing factors. In spectrum of microorganism atypical mycobacterium was highly related to surgical treatment（OR=16.5） as compared with other micro-organisms. Fungal infection was also related to surgery（OR=3.48）. But pseudomonal infection was reversely related to surgical treatment（OR=0.47）. Conclusions: Pseudomonas（37.9%） was the most common pathogens, followed by fungus（13.4%）, atypical mycobacterium（8.4%）, Staphylococcus（7.7%）, Streptococcus（7.4%）and Acanthamoeba（1.5%）. Atypical mycobacterial infection decreased significantly. Contact lens wear（45.4%） was the most common predisposing factors, followed by ocular trauma（22.6%）, chronic ocular and systemic disorder（17.1%）and ocular surgery（15%）. The contact lens wear increased and ocular trauma decreased significantly. Contact lens wear was highly related to pseudomonal infection. Recent ocular surgery was related to atypical mycobacterium infection. Ocular trauma was related to fungal infection. 73.5% of microbial keratitis was treated medically, and 26.5% needed surgical treatment. Bacterial keratitis was treated medically and surgery was inevitable in atypical mycobacterium and fungal keratitis. Fungal keratitis was the most common in cases treated by enucleation or evisceration. There was no increase in drug resistance in Pseudomonas, atypical mycobacterium, Staphylococcus and Streptococcus. Ciprofloxacin was better than cefazolin and gentamicin combination in drug susceptibility test in Gram-negative bacteria during 1994 to 2003. Cefazolin and ciprofloxacin combination regiment was better than cefazolin and gentamicin combination in drug susceptibility test in all bacteria. Pseudomonal keratitis was related to contact lens wear, short interval between symptom onset to definite treatment, large corneal erosion size, and medical treatment only. Atypical mycobacterial keratitis was related to ocular surgery factor, long interval between symptom onset to definite treatment, and additional surgical treatment. Fungal keratitis was related to old age and ocular trauma factor. Patients who were old and had longer time between symptom onset to definite treatment were prone to receive additional surgical treatment.

Purpose: To describe the microbiology results of corneal scrapings and morphology results of corneal ulcers over a one year period at the St John Eye Hospital with the following objectives: (i) to describe the positive culture results (ii) to describe the commonest causative organisms (iii) to describe resistance patterns to antibiotics (iv) to correlate the positive culture results with the clinical characteristics of the ulcer. Methods: A retrospective cross sectional review of patient medical records and microbiology reports of patients who presented with corneal ulcers at the St John Eye Hospital between October 2007 and October 2008. One hundred and fifty one (151) corneal scrapings submitted to the National Health Laboratory Services (NHLS) for microbiology, culture and sensitivity testing were analyzed. The following information was extracted from the microbiology reports and patient medical records: patient demographics, microbial isolations, antibiotic sensitivity and resistance, and corneal ulcer morphology (central versus peripheral). Results: Of the 151 patients who had corneal scrapings, 63(42%) were female and 88(58%) were male. The median age was 39.6(range 1-95; SD 19.3). An organism was identified in 78(52%) of the samples. Of the 93 pathogens isolated, 78(83.9%) were gram positive, 10(10.8%) were gram negative, and 5(5.4%) were fungi. Mixed isolates were found in 15 of the 151 corneal scrapings. The most common gram positive isolates were Staphylococcus aureus 23(29.5%), coagulase negative Staphylococcus 18(23.1%), and Streptococcus pneumoniae 16(20.5%). The two most commonly isolated gram negative organisms were Pseudomonas aeruginosa 3(30%) and Haemophilus influenza 3(30%). A total of 5 fungi were isolated from the 151 corneal scrapings with Fusarium 3(60%) being the most common fungus isolated. Antibiotic resistance patterns were as follows: Gram positive isolates (73) consistently showed 100% sensitivity to vancomycin. A small number of gram positive organisms showed in vitro resistance to the second generation fluoroquinolone ciprofloxacin. This was, however only a small number of gram positive isolates and therefore the P value (P<0.001) remained significant. Overall the gram positives isolates showed a 95.3% sensitivity to ciprofloxacin. Both second and fourth generation fluoroquinolones, ciprofloxacin and moxifloxacin respectively, showed equivalent (100%) in vitro activity against the gram negative isolates. All gram negative isolates showed 100% laboratory susceptibility to the aminoglycosides, gentamicin and amikacin. Inpatient medical records were available for 56 of the 151 corneal ulcer scrapings. Of the 56 inpatient records reviewed 42(75%) were central ulcers. Streptococcus pneumoniae 10(23.8%) was the most common organism isolated in central corneal ulcers, while staphylococcus aureus 4(28.6%) was the most common organism isolated in peripheral corneal ulcers. Conclusion: Compared with previous reports from the St John Eye Hospital, the spectrum of causative organisms has remained unchanged over the past 25 years. The organisms commonly responsible for microbial keratitis at the hospital are significantly susceptibility to the antibiotics currently being used as therapy.

Yes
Microbial keratitis can arise from penetrating injuries to the cornea. Corneal trauma promotes bacterial attachment and biofilm growth, which decrease the effectiveness of antimicrobials against microbial keratitis. Improved therapeutic efficacy can be achieved by reducing microbial burden prior to antimicrobial therapy. This paper assesses a highly-branched poly(N-isopropyl acrylamide) with vancomycin end groups (HB-PNIPAM-van), for reducing bacterial attachment and biofilm formation. The polymer lacked antimicrobial activity against Staphylococcus aureus, but significantly inhibited biofilm formation (p = 0.0008) on plastic. Furthermore, pre-incubation of S. aureus cells with HB-PNIPAM-van reduced cell attachment by 50% and application of HB-PNIPAM-van to infected ex vivo rabbit corneas caused a 1-log reduction in bacterial recovery, compared to controls (p = 0.002). In conclusion, HB-PNIPAM-van may be a useful adjunct to antimicrobial therapy in the treatment of corneal infections.
Medical Research Council and the Department of Biotechnology, India under grant number, MR/N50188/2.