Título

IN VITRO ANTIMICROBIAL ACTIVITY OF THE AQUEOUS HUMOR AFTER INSTILLATION OF TOBRAMYCIN 0.3% OR CHLORAMPHENICOL 0.4%

Objetivo

To analyze in vitro antimicrobial activity of the aqueous humor after instillation of Tobramycin 0.3% or Chloramphenicol 0.4%

Método

Aqueous humor samples were obtained from 48 eyes of 48 patients submitted to phacoemulsification. Patients were divided into 3 groups. Group 1, called the control group, did not receive instillation of antibiotic eye drops in the preoperative period. Each patient in group 2, received instillation of one drop of Tobramycin 0.3% once 30 to 60 minutes before the surgical procedure. Group 3, received a single drop of 0.4% chloramphenicol, once 30 to 60 minutes before the surgical procedure. Aspiration of aqueous humor samples were collected from the anterior chamber using a 26 gauge needle at the 12 o'clock position. The material was stored at sterile micro tube and then transported to the refrigerator to be maintained at -80 °C. Six American Type Culture Collection bacteria were studied: E. coli (25922), S. aureus (25923), S. epidermidis (12226), K. pneumoniae (13883), S. pneumoniae (49619) and P. aeruginosa (27853). Multi-resistant bacteria obtained from our outpatient clinic were also studied: S. aureus, S. epidermidis, K. pneumoniae, A. lwoffii, S. viridans, Pseudomonas aeruginosa and Serratia sp. The microorganisms were inoculated in Tryptic Soy Broth for turbidity standards corresponding to a concentration of 0.5 of the McFarland scale (1.5 x 108 colony forming units). The microorganisms were then seeded on the respective plaques. Aqueous humor sample from each study group were then pooled and 0.013μl of each sample were placed in a 6mm blank disc previously located in each bacteria plaque. Negative control for the blank disc was also performed. After 24 hours, the inhibition halos were measured with ruler.

Resultado

After 24 hours, no inhibition halos were observed on any of the microorganisms studied or in the control diffusion disc.

Conclusão

Aqueous humor after instillation of tobramycin and chloramphenicol did not show any antimicrobial activity in vitro.