Contact Lens-associated Microbial Keratitis Research Articles

Etiological and Clinical Features of Contact Lens-Associated Microbial Keratitis.

To determine the demographic, etiological, microbiological, and clinical characteristics and present treatment results of contact lens (CL)-associated microbial keratitis (CLAMK). Medical records of patients who were followed in our clinic for CLAMK between January 2014 and May 2020 were retrospectively analyzed. Demographic characteristics, symptom duration, CL and usage characteristics, risk factors, isolated microorganisms, lesion characteristics, hospital stay, recovery and follow-up times, and best corrected visual acuities (BCVA) at first and last examination were recorded. The 22 patients (16 females, 6 males; 22 eyes) had a mean follow-up time of 13.0±18.3 months and mean age of 26.9±14.3 years. Most of the female patients (13/16) were under 35 years old. At least one risk factor associated with improper CL usage was identified in 21 patients (95.4%). The most common risk factor was sleeping with CL (n=15, 68.1%). Causative microorganisms were detected on microbiological examination in 15 cases (68.1%). The most common microorganism was <i>Pseudomonas aeruginosa</i> (n=8). Causative pathogens were sensitive at rates of 84.2%, 95% and 94.7% to combined vancomycin/amikacin, combined vancomycin/ceftazidime, and moxifloxacin, respectively. Mean BCVA was 0.9±1.1 logMAR in the first examination and increased to 0.59±1.1 at last examination (p=0.006). There was a negative correlation between BCVA at presentation and length of hospital stay (p=0.014). Mistakes in CL use are a frequent predisposing factor in patients with CLAMK. Informing CL users in detail about CL usage and cleaning may reduce the frequency of these mistakes and thus infections. Current antibiotic options that should be preferred in empirical treatment remain largely effective against likely pathogens. Favorable visual outcomes can be obtained in most cases with detailed diagnostic examination and appropriate treatment approaches.

Therapy for contact lens-related ulcers.

The current review covers the current literature and practice patterns of antimicrobial therapy for contact lens-related microbial keratitis (CLMK). Although the majority of corneal ulcers are bacterial, fungus and acanthamoeba are substantial contributors in CLMK and are harder to treat due to the lack of commercially available topical medications and low efficacy of available topical therapy. Topical antimicrobials remain the mainstay of therapy for corneal ulcers. Fluoroquinolones may be used as monotherapy for small, peripheral bacterial ulcers. Antibiotic resistance is a persistent problem. Fungal ulcers are less responsive to topical medications and adjunct oral or intrastromal antifungal medications may be helpful. Acanthamoeba keratitis continues to remain a therapeutic challenge but newer antifungal and antiparasitic agents may be helpful adjuncts. Other novel and innovative therapies are being studied currently and show promise. Contact lens-associated microbial keratitis is a significant health issue that can cause vision loss. Treatment remains a challenge but many promising diagnostics and procedures are in the pipeline and offer hope.

Three Decades of Contact Lens-associated Microbial Keratitis in a Referral Hospital in São Paulo, Brazil.

The aim of this study was to analyze patient data and the laboratory results of corneal samples collected from patients followed at the Ophthalmology Department, Hospital São Paulo, Brazil over a 30-year period, and correlate the analize with contact lens wearing. Corneal samples from patients diagnosed clinically with microbial keratitis between January 1987 and December 2016 were included in this study. Cultures that were positive for bacteria, fungi, and Acanthamoeba spp. were analyzed retrospectively. To ascertain if the number of patients with contact-lens-associated microbial keratitis (as a risk factor for microbial infection) changed over time, the analysis was divided into three decades: 1987-1996, 1997-2006, and 2007-2016. Information pertaining to patient gender and age, as well as type of organism isolated, were compared among these periods. The corneal samples of 10.562 patients with a clinical diagnosis of microbial keratitis were included in the study, among which 1.848 cases were related to the use of contact lenses. The results revealed that the frequency of contact-lens-associated microbial keratitis increased over the last two decades. Overall, females had contact-lens-associated microbial keratitis more frequently (59.5%). Patients aged 19-40 years also had contact-lens-associated microbial keratitis more frequently in all study periods. Staphylococcus spp. and Pseudomonas spp. were the most frequent Gram-positive and Gram-negative bacteria, respectively, in the microbial keratitis groups. Among the fungal cases of microbial keratitis, filamentous fungi were the most frequent fungi over the entire study period, with Fusarium spp. being the most frequent fungi in the group with microbial keratitis not associated with contact lens wearing (p<0.001). Samples positive for Acanthamoeba spp. and Pseudomonas spp. were significantly correlated with contact-lens-associated microbial keratitis (p<0.001). Females and young adults aged 19-40 years exhibited the highest frequency of contact-lens-associated microbial keratitis in our study. Staphylococcus spp. and Fusarium spp. were the predominant bacteria and fungi, respectively, isolated from corneal samples. Pseudomonas spp. and Acanthamoeba spp. were significantly correlated with contact-lens-associated microbial keratitis in this study.

Contact Lens-Associated Microbial Keratitis in a Tertiary Eye Care Center in Turkey.

To evaluate the risk factors, causative microorganisms, and presenting features of infection in patients with contact lens-associated microbial keratitis (CLAMK) admitted to a tertiary referral center in Turkey. A retrospective review of the medical records of 62 patients who were diagnosed as CLAMK in our clinic between 2012 and 2018 was conducted. The mean age of the patients (22 men and 40 women) at the time of diagnosis was 24.5±8.3 years (range, 16-48). The mean best-corrected visual acuity (BCVA) was 0.7±0.9 log of minimal angle of resolution (logMAR) (0-3) before treatment and increased to 0.1±0.1 logMAR (0-0.4) at the end of the follow-up. All patients, except one using rigid gas-permeable CL, were frequent replacement soft CL users. Thirty-one (50%) patients declared overnight wear, and 37 (58.9%) patients declared showering or swimming in CLs regularly. Cultures of either corneal scrapings or CL materials were positive in 40 (64.5%) eyes, 12 (19.4%) of which had mixed infections. Thirteen strains of microorganisms were demonstrated, among which there were seven (53.8%) gram-negative bacteria, one (7.7%) gram-positive bacteria, four (30.7%) fungi, and Acanthamoeba (7.7%). The most common pathogen was Pseudomonas aeruginosa, followed by Serratia marcescens and Stenotrophomonas maltophilia. According to culture results, P. aeruginosa infections were associated with significantly worse BCVA. Keratitis foci were either centrally or paracentrally located in 39 (62.9%) eyes, and 16 eyes (25.8%) presented with hypopyon. Along with growing number of CL users, CLAMK constitutes an important problem with possibly worse visual outcomes. Thus, in addition to meticulous treatment, management of risk factors and behavioral modifications is crucial.

Contact lens-related corneal infection: Intrinsic resistance and its compromise.

Contact lenses represent a widely utilized form of vision correction with more than 140 million wearers worldwide. Although generally well-tolerated, contact lenses can cause corneal infection (microbial keratitis), with an approximate annualized incidence ranging from ~2 to ~20 cases per 10,000 wearers, and sometimes resulting in permanent vision loss. Research suggests that the pathogenesis of contact lens-associated microbial keratitis is complex and multifactorial, likely requiring multiple conspiring factors that compromise the intrinsic resistance of a healthy cornea to infection. Here, we outline our perspective of the mechanisms by which contact lens wear sometimes renders the cornea susceptible to infection, focusing primarily on our own research efforts during the past three decades. This has included studies of host factors underlying the constitutive barrier function of the healthy cornea, its response to bacterial challenge when intrinsic resistance is not compromised, pathogen virulence mechanisms, and the effects of contact lens wear that alter the outcome of host-microbe interactions. For almost all of this work, we have utilized the bacterium Pseudomonas aeruginosa because it is the leading cause of lens-related microbial keratitis. While not yet common among corneal isolates, clinical isolates of P. aeruginosa have emerged that are resistant to virtually all currently available antibiotics, leading the United States CDC (Centers for Disease Control) to add P. aeruginosa to its list of most serious threats. Compounding this concern, the development of advanced contact lenses for biosensing and augmented reality, together with the escalating incidence of myopia, could portent an epidemic of vision-threatening corneal infections in the future. Thankfully, technological advances in genomics, proteomics, metabolomics and imaging combined with emerging models of contact lens-associated P. aeruginosa infection hold promise for solving the problem - and possibly life-threatening infections impacting other tissues.

Study on Prevalence, Antibiotic Susceptibility, and tuf Gene Sequence–Based Genotyping of Species-Level of Coagulase-Negative Staphylococcus Isolated From Keratitis Caused by Using Soft Contact Lenses

To study on antibiotic susceptibility and identify coagulase-negative Staphylococcus (CoNS) species based on tuf gene sequencing from keratitis followed by using soft contact lenses in Isfahan, Iran, 2013. This study examined 77 keratitis cases. The samples were cultured and the isolation of CoNS was done by phenotypic tests, and in vitro sensitivity testing was done by Kirby-Bauer disk diffusion susceptibility method. Thirty-eight of isolates were conveniently identified as CoNS. In this study, 27 (71.1%), 21 (55.3%), and 16 (42.1%) were resistant to penicillin, erythromycin, and tetracycline, respectively. One hundred percent of isolates were sensitive to gentamicin, and 36 (94.7%) and 33 (86.8%) of isolates were sensitive to chloramphenicol and ciprofloxacin, respectively. Also, resistances to cefoxitin were 7 (18.4%). Analysis of tuf gene proved to be discriminative and sensitive in which all the isolates were identified with 99.0% similarity to reference strains, and Staphylococcus epidermidis had the highest prevalence among other species. Results of this study showed that CoNS are the most common agents causing contact lens-associated microbial keratitis, and the tuf gene sequencing analysis is a reliable method for distinguishing CoNS species. Also gentamycin, chloramphenicol, and ciprofloxacin are more effective than the other antibacterial agents against these types of bacteria.

Clinical presentation and morbidity of contact lens–associated microbial keratitis: a retrospective study

To investigate the clinical presentation, isolated organism, treatment, and morbidity of contact lens-associated microbial keratitis needing hospitalization. This retrospective study included all consecutive patients with contact lens-associated microbial keratitis hospitalized in the Rotterdam Eye Hospital from January 1, 2005, to December 31, 2009. All data regarding epidemiological characteristics, clinical presentation, isolated organism, and treatment were collected from medical records. There were 109 cases (108 patients) of contact lens-associated microbial keratitis hospitalized during the study period. Mean age was 33.3 ± 15.4 (SD) years. Pseudomonas aeruginosa was the most frequently isolated microorganism (68.8%), with minor resistance to gentamicin (2.7%) and ofloxacin (1.3%). At time of presentation, best corrected visual acuity (BCVA) was very poor, with the largest proportion of patients (65.1%) seeing worse than 0.05 Snellen. After intensive treatment, the visual outcome improved considerably, with the largest proportion (67.0%) achieving a BCVA ≥ 0.7 Snellen. Low BCVA at admission was significantly associated with a worse final BCVA. A total of 22 patients (20.2%) required corneal transplantation (three emergency cases). Larger size of stromal infiltrate was significantly associated with the need for corneal transplantation. Microbial keratitis is a serious complication of contact lens wear, with approximately one out of five hospitalized cases requiring corneal transplantation. Ofloxacin, or a combination of gentamicin and cephazolin, still appear to be excellent first-choice therapies in the Netherlands, as little resistance has developed to these antibiotics.

Potential Resistant Morphotypes of Acanthamoeba castellanii Expressed in Multipurpose Contact Lens Disinfection Systems

The free-living amoeba Acanthamoeba castellanii is a rare cause of contact lens-associated microbial keratitis. The cyst stage of this amoeba is noted for its resistance to disinfection by multipurpose contact lens solutions (MPS). This report examines and reviews the potential survival modes of A. castellanii in MPS. Trophozoites of A. castellanii (ATCC 30234) at densities from 10 to near 10 were incubated in 3 different MPS in a laminar flow hood for 24 hours at ambient temperatures. The dried films of MPS and phosphate-buffered saline (PBS) controls were examined before and after the addition of a peptone-yeast extract-glucose recovery broth (PYG) for the presence of amoeboid trophozoites and resistance stages over at least 7 days. The parallel exposure of trophozoites to MPS without evaporation or addition of PYG was similarly examined. Amoeboid trophozoites were not recovered in PYG nor were cyst-like structures observed in any MPS with near 10 densities. Progressively with 10 to 10 trophozoites, varied survival modes, particularly aggregates of trophozoites associated with cyst-like structures and occasional amoeboid forms and double-walled cysts with ostioles, became more evident. These morphotypes were most prominent after evaporation and typically first observed in the PYG. Trophozoites of A. castellanii near 10 and progressively to 10 densities are capable of expressing a variety of "short-term" survival modes in MPS, notably with the added stress of evaporation. Expression of these alternate survival modes in MPS may relate, in part, to contamination of contact lens cases and difficulties in developing standardized MPS efficacy tests.

Clinical management of infectious contact lens complications: from antibiotics to quorum-sensing inhibitors

Although effective drugs have become available, improvements in the treatment of contact lens-associated microbial keratitis are required. Over the last decade, the outcome of contact lens-associated bacterial keratitis has improved owing to fluoroquinolones, leading to a better control of infection, earlier institution of anti-inflammatory therapy and surgical intervention. The antimicrobial effectiveness of some antibiotics may be increased by preservatives. Antibiotic resistance according to serum standard limits has not been found to be relevant for the eye, with the exception of methicillin-resistant Staphylococcus aureus. Newer antifungals (voriconazole, itraconazole) are being evaluated, but the mainstay is liposomal amphotericin B and econzole or natamycin. Therapy for acanthamebic (biguanides and combinations) and microsporidial (fluoroquinolones) infections remains unchanged. New hydrophilic contact lens materials may slow down the formation of biofilm. Antibiofilm research has introduced substances that interfere with quorum sensing, and affect enzymatic and peptide-mediated matrix dispersal. Nanotechnology will be used to penetrate the biofilm matrix as well as nanoetching to prevent biofilm development on surfaces. Management of contact lens keratitis comprises of management of the biofilm. Early aggressive antimicrobial treatment, and surgery in certain cases, have resulted in better outcomes. The role of corticosteroids seems beneficial, but has to be further studied. Further improvements rely on biofilm-active agents added to antimicrobials.

Contact lens-associated microbial keratitis

Contact lens-associated microbial keratitis is a severe condition with sight-threatening potential and increasing incidence. Information regarding the etiological agents is essential in guiding management and may vary geographically. The aim of this study was to analyze the microbiological results of corneal scrapings collected from patients presenting with contact lens-associated microbial keratitis. Retrospective analysis of the records of all patients who were clinically diagnosed with contact lens-associated microbial keratitis and had corneal scrapings sent to the Laboratory of Ocular Microbiology, UNIFESP/EPM during a 5-year period from January 2002 to December 2007. The etiological agent was identified in 239 patients. Bacterial isolates accounted for 166 (69.46%) cases, Acanthamoeba for 95 (39.75%) cases and fungi for 4 (1.67%) cases. Among the bacterial infections, coagulase-negative Staphylococcus was demonstrated in 74 cases, while Pseudomonas spp was found in 32 patients. All coagulase negative Staphylococcus and Pseudomonas were susceptible to ciprofloxacin and ofloxacin. Resistance to gentamicin was documented in a single case of Pseudomonas. Fourth-generation flouoroquinolone resistance was not observed among Pseudomonas cases. Coagulase-negative Staphylococcus was the most frequent isolate, and such data must be considered when determining empiric treatment. Second-generation fluoroquinolones ciprofloxacin and ofloxacin and fourth-generation fluoroquinolones moxifloxacin and gatifloxacin showed a good antibacterial profile and therefore could be good options for initial management.

Clinical Features and Outcomes of Fusarium Keratitis Associated With Contact Lens Wear

To describe the clinical features and outcomes among contact lens wearers with Fusarium keratitis. A retrospective observational review of all cases of culture-proven Fusarium keratitis among contact lens wearers from three hospitals in Hong Kong Island were included. The clinical features, hygiene habits, and clinical outcomes were reviewed. Sixteen patients (17 eyes) were diagnosed with Fusarium keratitis associated with contact lens wear. One patient had bilateral involvement. Six patients had a central lesion; four had paraxial lesions; one had paraxial and peripheral lesions; and the rest had peripheral lesions. Ten (62.5%) patients reported using ReNu multipurpose cleaning solution. Most patients had poor contact lens hygiene habits. One patient required systemic antifungal treatment. No surgical intervention was required in any of the patients. The clinical features of Fusarium keratitis in contact lens wearers can be variable. Although fungal infection is reported rarely, clinicians should maintain a high index of suspicion for it when examining patients with contact lens-associated microbial keratitis. Education on proper contact lens care should be reinforced. Early and appropriate treatment may lead to satisfactory visual outcomes.

Recent Pattern of Contact Lens–Related Keratitis in Hong Kong

To describe the changing pattern of clinical features and microbiology of contact lens-associated microbial keratitis in Hong Kong. This is a retrospective observational case series of patients diagnosed with contact lens-associated microbial keratitis between July 2004 and April 2005 and between July 2005 and April 2006. Patients who wore contact lenses solely for the correction of refractive error and who were seen at Queen Mary Hospital were included in the study. The clinical characteristics, microbiology, and visual outcomes were compared. There were 14 cases between July 2004 and April 2005. Most cases had an axial lesion (eight) or paraxial lesions (four). Corneal scrapings were positive in seven (50%) patients, among whom six showed Pseudomonas aeruginosa and one showed Serratia marcescens as the pathogens. Contact lens storage cases yielded polymicrobial growth in two cases. For the more recent cohort, Fusarium species had been identified as the dominant pathogen, and most (60%) contact lens storage cases showed polymicrobial growth. There has been an increased number of cases of contact lens-associated fungal keratitis recently. Fusarium species and polymicrobial growth are becoming more dominant.

Modulation of bacterial adhesion to hydrogel contact lenses by albumin.

The purpose of this investigation was to measure the abilities of Pseudomonas aeruginosa and Staphylococcus epidermidis strains to adhere to two hydrogel lens materials and measure the effect of a protein-coated surface on the number of adhered bacteria. Proteins absorbed to contact lenses during sleep were extracted, subjected to sodium dodecylsulphate polyacrylamide gel electrophoresis (SDS-PAGE), and probed for the presence of albumin. Bacterial adhesion was measured by counting bacteria adherent to contact lenses coated in vitro in increasing concentrations of albumin, examining the ability of albumin in solution to prevent adhesion to albumin-coated lenses, and examining the topography of bacterial adhesion by electron microscopy. Albumin adsorbed to lenses during overnight wear. In vitro studies demonstrated that Polymacon lenses adsorbed more albumin than Etafilcon A lenses. In general, the numbers of adherent bacteria increased with increasing concentration of albumin. Bacteria adhered in higher numbers to Polymacon lenses than Etafilcon A (p < 0.05). P. aeruginosa showed an increased adhesion as the amount of albumin on Etafilcon A lenses increased. There was a decrease in numbers of bacteria adhering per milligram of albumin as the level of albumin increased on Polymacon lenses. Cells tended to adhere to "deposits" on albumin-coated lenses. Albumin adsorbed onto the surface of contact lenses modulated the ability of P. aeruginosa and S. epidermidis to adhere. P. aeruginosa is commonly associated with contact lens-associated microbial keratitis, where bacterial adhesion to contact lenses is believed to be an important first step in the pathogenesis of the disease.