Factors influencing the contamination rates of the conjunctival swabs and organ culture media of human donor eyes

Abstract

This study assessed the influence of donor, environmental, and logistical factors on the contamination rates of the conjunctival swabs and organ culture media of human donor eyes.In total, 1008 conjunctival swabs and 418 organ culture media samples from 504 consecutive human donor eyes were analyzed. Cross-tabulation, chi-squared tests, and Fisher's exact tests were used to assess the influence of the different factors on the contamination rates of the conjunctival swabs and organ culture media.The overall contamination rates were 28.4% for the conjunctival swabs and 1.0% for the organ culture media. A prolonged time between death and the conjunctival swab collection was associated with an increased conjunctival swab contamination rate [odds ratio (OR) = 1.9, 95% confidence interval (CI) = 1.2–3.0, P = .007]. The highest conjunctival swab contamination rate was found in the corneas procured in external institutions (outside the university hospital) (44.1%, OR = 3.6, 95%CI = 1.5–8.4, P = .003). Hospitalization times of 2 to 7 days prior to death were associated with an increased conjunctival swab contamination risk (OR = 2.6, 95%CI = 1.1–5.8, P = .021). However, the sex, age, cause of donor death, differentiation between septic and aseptic donors, differentiation between heart-beating brain-dead multiorgan donors and cadaveric donors, a warmer mean monthly temperature, and death to corneoscleral disc excision time did not significantly increase the conjunctival swab contamination risk. In addition, none of these factors affected the organ culture media contamination risk. Moreover, a positive conjunctival swab did not significantly increase the media contamination risk (P = .08). Surprisingly, the microorganisms causing media contamination were present at 50% of the amount detected on the conjunctival surface of the respective donor eye.A prolonged time between death and the conjunctival swab collection, a hospitalization time of 2 to 7 days prior to death, and corneal collection outside the university hospital seemed to be the main factors responsible for an increased conjunctival swab contamination risk. In addition, our investigation illustrated that a positive conjunctival swab is not a strong indicator for organ culture media contamination. Critical discussion is necessary regarding the validity of conjunctival swabs as prognostic parameters for organ culture media contamination.

Donor-Dependent Factors Influencing Contamination Rates of Conjunctival Swabs of Human Donor Eyes

“…The mean time between death and the conjunctival swab collection was 12.4±15.0 h. In 2018, our study group showed that a prolonged time interval between death and the conjunctival swab collection was significantly associated with an increased conjunctival swab contamination risk [17].…”

“…However, in total, we decontaminated the donor eyes for at least 8 min in low concentrations of povidone-iodine and transported the eyes separately in cooled sterile urine cups filled with 5 ml of gentamicin eye drops between the 2 decontaminations. Our extensive decontamination protocol, as described above, could explain why our organ culture media contamination rate of 1.0% was lower than the rates of 4.5% to 10.8% found by Li et al, who cleaned the periocular region with a 7.5% povidone-iodine solution spray and the ocular surface with a 1.25% povidone-iodine solution for 3 and 5 min, respectively [11,17].…”

“…In 2018, our study group showed that a prolonged time interval between death and conjunctival swab collection, a hospitalization time of 2–7 days prior to death, and corneal collection outside the university hospital seemed to be the main factors responsible for an increased conjunctival swab contamination risk [17]. This exciting investigation inspired us to examine the effect of particular donor-dependent factors on the contamination rates of conjunctival swabs of human donor eyes.…”

Comparison of Microbial Sampling Sites and Donor-Related Factors on Corneal Graft Contamination

“…Hermel et al, used an automated test detection system to investigate the optimal time for sterility testing [ 15 ]. Sterile swabs were used to inspect the donor’s upper and lower conjunctiva for microbial detection after povidone-iodine disinfection [ 16 ]. Thus, microbial sampling for corneal grafts is not standardized and remains a controversial issue.…”

Factors influencing the contamination rates of the conjunctival swabs and organ culture media of human donor eyes: Erratum

“…In the article, “Factors influencing the contamination rates of the conjunctival swabs and organ culture media of human donor eyes”, [ 1 ] which appears in Volume 97, Issue 38 of Medicine , the sentence “The different factors evaluated did not have an effect on the 8 organ culture media samples tested, and a positive conjunctival swab did not significantly increase the medium contamination risk” on page 4 should appear as “The different factors evaluated did not have an effect on the organ culture media samples tested, and a positive conjunctival swab did not significantly increase the medium contamination risk.”…”