Aims. To compare HB&L and BACTEC systems for detecting the microorganisms contaminating the corneal storage liquid preserved at 31°C. Methods. Human donor corneas were stored at 4°C followed by preservation at 31°C. Samples of the storage medium were inoculated in BACTEC Peds Plus/F (aerobic microorganisms), BACTEC Plus Anaerobic/F (anaerobic microorganisms), and HB&L bottles. The tests were performed (a) after six days of storage, (b) end of storage, and (c) after 24 hours of preservation in deturgescent liquid sequentially. 10,655 storage and deturgescent media samples were subjected to microbiological control using BACTEC (6-day incubation) and HB&L (24-hour incubation) systems simultaneously. BACTEC positive/negative refers to both/either aerobic and anaerobic positives/negatives, whereas HB&L can only detect the aerobic microbes, and therefore the positives/negatives depend on the presence/absence of aerobic microorganisms. Results. 147 (1.38%) samples were identified positive with at least one of the two methods. 127 samples (134 identified microorganisms) were positive with both HB&L and BACTEC. 14 HB&L+/BACTEC？ and 6 BACTEC+/HB&L？ were identified. Sensitivity (95.5%), specificity (99.8%), and positive (90.1%) and negative predictive values (99.9%) were high with HB&L considering a 3.5% annual contamination rate. Conclusion. HB&L is a rapid system for detecting microorganisms in corneal storage medium in addition to the existing methods. 1. Introduction Endophthalmitis is a microbial infection within the eye that results in severe inflammation. It is a severe complication of intraocular surgeries like penetrating keratoplasty (PK) or cataract surgery where the risk of bacterial or fungal infection increases with transplantation of a contaminated cornea [1, 2]. It has been shown that the microorganisms responsible for the postoperative endophthalmitis are usually derived from the transplanted corneas; however, involvement of other postoperative risk factors for ocular infection has also been determined [3]. The growth of bacterial strains susceptible to the antibiotics (typically penicillin and streptomycin) and antifungal substances (amphotericin B) added to the preservation medium allows to determine the microbial growth and eventually discard the contaminated cornea. The presence of bacteria is not always indicated by the turbidity or the yellowish appearance of the culture medium; therefore, both the efficacy and sensitivity of the detection method of microbial contamination become a critical factor. Moreover, if long-term organ culture is
References
[1]
A. S. Leveille, F. D. McMullan, and H. D. Cavanagh, “Endophthalmitis following penetrating keratoplasty,” Ophthalmology, vol. 90, no. 1, pp. 38–39, 1983.
[2]
S. J. Linke, O. H. Fricke, M. T. Eddy, et al., “Risk factors for donor cornea contamination: retrospective analysis of 4546 procured corneas in a single eye bank,” Cornea, vol. 32, no. 2, pp. 141–148, 2013.
[3]
U. Rehany, G. Balut, E. Lefler, and S. Rumelt, “The prevalence and risk factors for donor corneal button contamination and its association with ocular infection after transplantation,” Cornea, vol. 23, no. 7, pp. 649–654, 2004.
[4]
L. Pels, “Organ culture: the method of choice for preservation of human donor corneas,” British Journal of Ophthalmology, vol. 81, no. 7, pp. 523–525, 1997.
[5]
J. Albon, M. Armstrong, and A. B. Tullo, “Bacterial contamination of human organ-cultured corneas,” Cornea, vol. 20, no. 3, pp. 260–263, 2001.
[6]
European Eye Bank Association, Agreements on minimum standards, 2008.
[7]
P. Gain, G. Thuret, C. Chiquet et al., “Use of a pair of blood culture bottles for sterility testing of corneal organ culture media,” British Journal of Ophthalmology, vol. 85, no. 10, pp. 1158–1162, 2001.
[8]
G. Thuret, P. Gain, A. Carricajo et al., “Sensitivity and rapidity of blood culture bottles in the detection of cornea organ culture media contamination by bacteria and fungi,” British Journal of Ophthalmology, vol. 86, no. 12, pp. 1422–1427, 2002.
[9]
G. Thurel, A. Carricajo, A. C. Vautrin et al., “Efficiency of blood culture bottles for the fungal sterility testing of corneal organ culture media,” British Journal of Ophthalmology, vol. 89, no. 5, pp. 586–590, 2005.
[10]
C. Fontana, M. Favaro, S. Minelli, M. C. Bossa, A. Altieri, and C. Favalli, “A novel culturing system for fluid samples,” Medical Science Monitor, vol. 15, no. 2, pp. BR55–BR60, 2009.
[11]
E. Zanetti, A. Bruni, G. Mucignat, D. Camposampiero, A. C. Frigo, and D. Ponzin, “Bacterial contamination of human organ-cultured corneas,” Cornea, vol. 24, no. 5, pp. 603–607, 2005.
[12]
P. M. Bossuyt, J. B. Reitsma, D. E. Bruns et al., “Towards complete and accurate reporting of studies of diagnostic accuracy: the STARD initiative. Standards for Reporting of Diagnostic Accuracy,” Clinical Chemistry, vol. 49, no. 1, pp. 1–6, 2003.
[13]
C. J. Clopper and E. S. Pearson, “The use of confidence or fiducial limits illustrated in the case of the binomial,” Biometrika, vol. 26, no. 4, pp. 404–413, 1934.
[14]
R. Jaeschke, G. H. Guyatt, and D. L. Sackett, “User's guides to the medical literature: III. How to use an article about a diagnostic test: B. What are the results and will they help me in caring for my patients? The Evidence-Based Medicine Working Group,” Journal of the American Medical Association, vol. 271, no. 9, pp. 703–707, 1994.
[15]
D. L. Simel, G. P. Samsa, and D. B. Matchar, “Likelihood ratios with confidence: sample size estimation for diagnostic test studies,” Journal of Clinical Epidemiology, vol. 44, no. 8, pp. 763–770, 1991.
[16]
T. Andrea, S. Laura, C. Antonietta, P. S. Giuseppe, C. Mario, and P. Giorgio, “Evaluation of the Uro4 HB&L system for the rapid diagnosis of lower respiratory tract infections in intensive care units,” Journal of Microbiological Methods, vol. 81, no. 3, pp. 235–239, 2010.
[17]
B. S. Reisner and G. L. Woods, “Times to detection of bacteria and yeasts in BACTEC 9240 blood culture bottles,” Journal of Clinical Microbiology, vol. 37, no. 6, pp. 2024–2026, 1999.
