Decontamination of human sclera: an in vitro study.
OBJECTIVE
The human sclera is frequently used in ophthalmic surgeries and must be preserved in disinfectants that prevent its contamination. In this study the efficiency of glycerin, absolute alcohol (ethanol), and benzalkonium chloride (1:5,000) as human sclera disinfectants were compared.


METHODS
Fresh human scleras were trephined, the scleral disks divided into three groups and contaminated with Staphylococcus aureus (ATCC 29213), Pseudomonas aeruginosa (ATCC 27853), or Bacillus cereus (ATCC 11778) for 24 h. Thereafter they were transferred to preservation vials each containing glycerin, absolute alcohol, benzalkonium chloride diluted in 70% alcohol (1:5,000) or Trypticase Soy Broth (control), respectively, and stored at room temperature. From each vial, two scleral disks were removed after 1, 2, 3, 4, 7, 10, and 14 days of immersion. Both were plated on blood agar, one being macerated, and both incubated at 37 degrees C for 48 h.


RESULTS
Pseudomonas aeruginosa, S. aureus, and B. cereus were recovered from the glycerin-immersed scleral disks until the second, fourth, and fourteenth days, respectively. Bacillus cereus was recovered from those immersed in absolute alcohol until the fourteenth day, whereas disks infected with the other microorganisms and immersed in absolute alcohol presented no growth since the very first day of immersion. Bacillus cereus was recovered from scleral disks immersed in benzalkonium chloride diluted in 70% alcohol (1:5,000) only on the first day.


CONCLUSIONS
Resistant microorganisms can survive in scleral tissue preserved in glycerin and absolute alcohol. We conclude that benzalkonium chloride diluted in 70% alcohol (1:5,000) in vitro is the best disinfectant for human sclera after 24 h.
Lucci
L M
LM
Department of Ophthalmology, Federal University of São Paulo, Brazil. miriam1@nvc.com.br
Yu
M C
MC
Höfling-Lima
A L
AL
D001409:Bacillus cereus / Q000187:drug effects* / Q000254:growth & development; D001548:Benzalkonium Compounds / Q000494:pharmacology; D015169:Colony Count, Microbial; D003666:Decontamination / Q000379:methods*; D004352:Drug Resistance, Microbial; D000431:Ethanol / Q000494:pharmacology; D005990:Glycerol / Q000494:pharmacology; D006801:Humans; D008826:Microbial Sensitivity Tests; D011310:Preservatives, Pharmaceutical / Q000494:pharmacology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000254:growth & development; D012590:Sclera / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000254:growth & development; D014021:Tissue Preservation
D001548:Benzalkonium Compounds; D011310:Preservatives, Pharmaceutical; D000431:Ethanol; D005990:Glycerol