Purpose:
To evaluate, in vitro, the long-term antimicrobial efficacy of the corneal storage medium (CSM) containing gentamicin and streptomycin (Optisol-GSTM) in strains of Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Streptococcus agalactiae, Streptococcus pyogenes, Pseudomonas aeruginosa, Escherichia coli and Candida albicans using a closed chamber study model.
Methods:
Samples of contamined CSM were analyzed in different moments after contamination with a microbial concentration of 1,5 x 108CFU/ml. Samples were analyzed at 1 hour; 2 hours; 3 hours; 4 hours; 5 hours; 6 hours; 24 hours; 48 hours; 72 hours; 7 days; 10 days; and 14 days after contamination. The samples were analyzed using a study model system that consists of two closed chambers. The upper chamber contains 3 culture media (chocolate agar, MacConkey agar and Sabouraud agar). The inferior chamber contains a supplemented solution. The microbial growth parameters were analyzed by the presence or absence of microorganism in the culture media. First reading was performed after 24 hours and, in the absence of bacterial growth, further readings were carried out after 48 and 72 hours.
Results:
We observed growth of Staphylococcus aureus, Pseudomonas aeruginosa and Streptococcus pneumoniae in the first reading in samples of the moment of contamination until 7 days after contamination, Staphylococcus epidermidis, Streptococcus agalactiae and Candida albicans in samples of the moment of contamination until 14 days after contamination, Streptococcus pyogenes in samples of the moment of contamination until 72 hours after contamination and Escherichia coli in samples of the moment of contamination until 48 hours after contamination. We observed growth of Staphylococcus aureus and Pseudomonas aeruginosa in the third reading in samples of the 14th day after contamination and Escherichia coli in sample of the 72nd hour after contamination.
Conclusions:
There is microbial activity in the CSM until 14 days after its contamination.
Keywords: cornea: storage • antibiotics/antifungals/antiparasitics • cornea: basic science