A presentation of culture-positive corneal donors and the effect on clinical outcomes.

PURPOSE: Donor-to-host transmission of infectious agents is a rare but well-recognised complication of corneal transplantation and may carry a grave visual prognosis. In this case series, we describe the clinical features and risk factors of using culture-positive donor corneas for transplantation. METHODS: Retrospective chart review of a series of patients who underwent either penetrating keratoplasty (PK) or Descemet's stripping automated endothelial keratoplasty (DSAEK) with positive microbiology cultivation during routine assessment of donor corneal tissue obtained at the time of surgery. Donor and recipient characteristics, tissue preparation and surgical parameters, clinical signs and outcomes were registered. RESULTS: Eleven patients who received culture-positive corneal grafts were identified: six with Candida, three with Gram-positive bacteria and two with Gram-negative bacteria. Three patients developed clinical keratitis after routine DSAEK using corneas contaminated with Candida species. The median death-to-preservation time (DPT) of these three donor corneas was 18.08 (range 18.08 to 20.90) h, while in the remaining eight donors, it was 12.27 (range 9.32 to 20.47) h. Despite the initiation of antifungal treatment, all three cases required explantation of the graft and a subsequent re-DSAEK. CONCLUSIONS: The use of donor corneas that are culture-positive for Candida carries a risk for developing postoperative keratitis and the risk may be higher in DSAEK. Unlike the cold storage technique employed for donor corneas described in this case series, organ culture technique requires microbiological screening and supplementation of an antifungal agent which may reduce the risk of donor-to-host transmission of fungal infection.

Serologic Evaluation of Cornea Donors and Microbiologic Evaluation of Cornea Storage Media in an Eye Bank from Izmir, Turkey.

OBJECTIVES: Our objective was to evaluate the serologic positivity of cornea donors and microbiologic positivity of cornea storage media at the Ege University Tissue and Cornea Bank, Izmir, Turkey. MATERIALS AND METHODS: We retrospectively investigated the serologic blood sample and microbiological culture media analysis results of all cornea donors at Ege University Tissue and Cornea Bank between 2007 and 2015 with reference to age, sex, and cause of death of each donor. RESULTS: Mean age of the 955 deceased donors was 43.19 ± 15.89 years (range, 2-65 y). The mean postmortem time to blood sample removal and excision of the cornea tissue was 8.4 hours (range, 4-12 h). Serologic analyses showed that 855 donors (89.5%) were seronegative. The remaining donors were seropositive for hepatitis B (54 donors; 5.7%), human immunodeficiency (27 donors; 2.8%), hepatitis C (14 donors; 1.5%), and syphilis (5 donors; 0.5%) virus infections. Microbiologic analyses of the storage media were negative, with no microorganisms shown in 855 samples (89.5%). Candida species (32 donors; 3.4%), Escherichia coli (14 donors; 1.5%), Pseudomonas aeruginosa (11 donors; 1.2%), methicillin-resistant Staphylococcus aureus (11 donors; 1.2%), Enterobacter species (11 donors; 1.2%), Klebsiella pneumoniae (7 donors; 0.7%), Acinetobacter baumannii (6 donors; 0.6%), Proteus species (5 donors; 0.5%), and Corynebacterium species (3 donors; 0.3%) were the detected microorganisms in the infected storage media. CONCLUSIONS: False-positive serologic results among cornea donors were high. The incidence of false-positive results might be decreased by earlier blood removal from deceased donors and testing of all potential donors in intensive care units. Although rare, endophthalmitis after keratoplasty might be a devastating problem. In addition to serologic testing, microbiologic analyses of cornea storage media before transplant may be an effective way to prevent postoperative infectious complications.

Vertical transmission of bacterial eye infections, Angola, 2011-2012.

To determine transmission rates for neonatal conjunctivitis causative microorganisms in Angola, we analyzed 312 endocervical and 255 conjunctival samples from mothers and newborns, respectively, during 2011-2012. Transmission rates were 50% for Chlamydia trachomatis and Neisseria gonorrhoeae and 10.5% for Mycoplasma genitalium. Possible pathogenic effects of M. genitalium in children's eyes are unknown.

Clostridium perfringens endophthalmitis after penetrating keratoplasty with contaminated corneal allografts: a case series.

PURPOSE: To report the postoperative clinical course of 3 patients who underwent corneal transplantation with corneal allografts contaminated with Clostridium perfringens and to evaluate the risk factors for anaerobic contamination in 2 donors. METHODS: Patient records and adverse reaction reports from a single eye bank related to cases of posttransplant C. perfringens endophthalmitis were reviewed. Records regarding the mated corneas, donor autopsy reports, and other pertinent data were also reviewed. RESULTS: Three adverse reactions associated with transplantation of corneal allografts contaminated with C. perfringens were reported. Two cases were from mated corneas. Both patients developed fulminant endophthalmitis after undergoing uncomplicated penetrating keratoplasty and required subsequent enucleation. Another isolated case (with no adverse reaction in the mate cornea) developed hypopyon postoperatively that resolved with intravitreal and topical antibiotics. Possible risk factors for anaerobic tissue contamination in the donors included illicit drug use in the first donor and exposure to sewage at the time of death in the second donor. CONCLUSIONS: Clostridial endophthalmitis is an aggressive rapidly progressive infection with potentially poor visual outcomes that can be transmitted from infected corneal allografts. Further investigation is needed to clarify the role of anaerobic donor rim cultures and the donor risk factors associated with recovering corneal allograft tissue contaminated with C. perfringens.

Hand hygiene prior to contact lens handling is problematical.

PURPOSE: To establish guidelines for contact lens wearers' hand hygiene practices which achieve a balance between minimising risk of infection and reasonable expectations on the ability of patients to follow them. METHODS: Evidence has been obtained from publications via PubMed, Advanced Medline Search, Cochrane Reviews, Google Scholar and using the key words hand hygiene, washing and contact lens. RESULTS: Guidelines for effective hand washing and the bother involved vary according to the level of hygiene required. High levels of non-compliance with hand hygiene practices, even among healthcare workers, gives an indication of how important the level of bother involved when following guidelines can be in contributing to non-compliance. CONCLUSIONS: Better patient education to improve hand washing techniques as well as patient attitudes toward hand hygiene are needed to reduce high non-compliance levels. Better hand hygiene techniques and higher frequency of their application give the prospect of reduced risk of infection and of any discomfort that arises from increased lens and ocular bioburden. In order that adoption rates might be maximised, the guidelines which have been distilled from this review attempt to strike a balance between technique redundancy and the associated higher levels of hygiene achieved and the possibility that the perception of too much bother involved could reduce participation rates. The guidelines have been expanded by the inclusion of suggested explanatory information in the expectation that helping patients to understand why the recommendations are made will have the effect of increasing their adoption.

Force analysis of bacterial transmission from contact lens cases to corneas, with the contact lens as the intermediary.

PURPOSE: To determine the probability of transmission of a Staphylococcus aureus strain from a contact lens case, to the contact lens (CL) surfaces, to the cornea, on the basis of bacterial adhesion forces measured by using atomic force microscopy (AFM). METHODS: Adhesion forces between S. aureus strain 835 probes with rigid and soft CLs, storage cases, and porcine corneas were measured with AFM and used to calculate Weibull distributions, from which the transmission probability from one surface to another was derived. Bacterial transmission probabilities from force analyses were compared with experimentally obtained transmission data. RESULTS: After bond-strengthening, S. aureus adhered to the surface of a lens case with a median force of 10.8 nN. Adhesion forces were different on the soft and rigid CLs (7.7 and 13.6 nN, respectively). Adhesion forces on porcine corneas amounted to 11.8 nN. Data variations were used to calculate the Weibull distribution, from which the probability of transmission from the lens case to a CL and from the CL to the cornea can be directly read. Final transmission probabilities from lens case to the cornea were slightly higher for the rigid (24%) than for the soft (19%) CL. Bacterial transmission determined experimentally increased with increasing contact times, but were within the range of the probabilities derived from Weibull analyses. CONCLUSIONS: Probabilities of bacterial transmission from contaminated lens cases to corneas can be derived from Weibull analyses of measured forces of adhesion to the surfaces involved.

The reuse of opthalmic Minims: an unacceptable cross-infection risk?

AIMS: The instillation of a combined fluorescein-anaesthetic eye drop is common practice in most ophthalmology clinics. Chauvin Pharmaceuticals produce unpreserved proxymethacaine 0.5% and fluorescein 0.25% in a Minims vial (PFM) intended for single application only. Our aim was to determine whether the reuse of these eye drops for multiple applications has the potential for bacterial transmission. METHODS: Samples were collected from doctors in general outpatient clinics. Each sample constituted a blood agar plate inoculated with the initial drop of fluid from a PFM as a control. The vial was then used for multiple applications on consecutive patients. One of the last remaining drops was then inoculated onto an alternate marked site on the same plate to serve as the test sample. The samples were immediately transported to the Microbiology laboratory and incubated at 37 degrees C for 48 h. The results were interpreted thereafter by a Microbiologist. RESULTS: A total of 41 samples were collected by eight Samplers. In all, 7/41(17%) samples showed growth of normal conjunctiva and lid flora on the test area. These were coagulase negative Staphylococci and Corynebacterium spp. CONCLUSIONS: The reuse of single application of PFM should be questioned due to the potential risk of transmitting pathogens. A change to a single use only policy would result in a projected threefold increase in the annual budget for these drops.

Minimizing the risk of disease transmission during corneal tissue processing.

Corneal transplantation is undergoing significant change because the dysfunctional portion of the cornea may now be selectively transplanted. After recovery of corneoscleral tissue, further processing of such tissue as in microkeratome preparation of endothelial keratoplasty lenticules is defined as "open-container processing" by the Eye Bank Association of America. Airborne bacterial contamination during preparation of corneal tissue is a potential source of postoperative infection. This review addresses ways to minimize the risk of disease transmission as corneal tissue is processed for lamellar keratoplasty, endothelial keratoplasty, or femtosecond laser-assisted penetrating keratoplasty and to minimize risk to eye bank personnel or physicians preparing the tissue. Secondly, quality assurance measures are described that qualify the environment in which corneal tissue is being processed. We propose that the environment in which corneal tissue is being processed must be able to demonstrate acceptable levels of airborne microbial contamination annually as measured by settle plates to estimate airborne bacterial sedimentation. It is recommended that any environment where corneal tissue is prepared should meet the minimum standard of a conventional operating room which is <25 colony-forming unit per 90-mm settle plate per 1-hour exposure.

Frequency of positive donor rim cultures after penetrating keratoplasty using hypothermic and organ-cultured donor corneas.

PURPOSE: To compare the frequency of positive rim cultures after penetrating keratoplasty using corneas preserved by hypothermic and organ culture storage. To evaluate the influence of standard procurement techniques on the frequency of microbial donor rim contamination. METHODS: Six hundred four donor corneas stored at 31 degrees C and 214 at 4 degrees C were studied. Microbiology studies were carried out during organ culture storage, and corneas with positive medium cultures were discarded. Frequency of postoperative positive rim cultures was related to the type of corneal storage and procurement technique used. RESULTS: Thirty-nine (6.4%) corneas with positive medium cultures were discarded during organ culture. Microbiology reports of 628 donor rims cultures from 671 (94%) consecutive transplants were reviewed. Positive rim cultures resulted in 24 (3.8%) cases. None of the patients developed endophthalmitis. The frequency of postoperative positive rim cultures was greater after hypothermic than organ culture storage, being 9.8% and 1.3%, respectively (chi(2) = 24.9; P < 0.001). With organ culture storage, the frequency of positive rim cultures was 1.3% and 1.4% after enucleation and in situ corneal excision, respectively (chi(2) = 0.03; P = 0.638). After hypothermic storage, positive rim cultures were found in 8% of the corneas procured using enucleation and 12% of the corneas excised in situ (chi(2) = 0.829; P = 0.254). CONCLUSIONS: Organ culture storage allows one to recognize and discard corneas with microbial contamination during storage. This method significantly reduces the frequency of postoperative positive rim cultures compared with hypothermic storage. Procurement methods do not influence the percentage of positive rim cultures.

Multivariate analysis of childhood microbial keratitis in South India.

INTRODUCTION: Corneal infection is the most common cause of profound ocular morbidity leading to blindness worldwide. Corneal infection in children is difficult to diagnose and treat, as they are unwilling and sometimes unable to cooperate during active management. This study analyses the prevalence, microbiology, demography, therapeutic and visual outcome of infectious microbial keratitis in the paediatric age group seen at a tertiary eye care hospital in south India. MATERIALS AND METHODS: A retrospective review of all cases presenting with keratitis to the ocular microbiology and cornea service at Aravind Eye Hospital, Coimbatore, from February 1997 to January 2004, was done to screen the patients for microbial keratitis. Their records were further analysed for clinical and microbiological details. Cases with culture-proven non-viral keratitis in children

Microbial keratitis in ITU staff: an occupational hazard?

Microbial keratitis is a potentially blinding corneal infection; the infection may progress rapidly if untreated and result in corneal perforation. The breakdown of the innate ocular defences is known to predispose to corneal infection. We present three cases of microbial keratitis in intensive therapy unit (ITU) staff each of whom had compromised corneal immunity. Anaesthetists and nurses regularly perform high-risk procedures, such as tracheal suctioning, which have been known to cause ocular infections by aerosol inoculation. We suggest that although the absolute risk of infection is low, susceptible individuals may be at increased risk of corneal infection from exposure to potentially pathogenic organisms in such environments. We stress the need for ITU staff, particularly those who wear contact lenses, to wear eye protection when performing procedures likely to cause infected aerosols.