Isolation of conjunctival mucin and differential interaction with Pseudomonas aeruginosa strains of varied pathogenic potential

The purpose of the study was to investigate the adhesion of Pseudomonas aeruginosa strains with varying pathogenic potential to purified ocular mucin. Bovine conjunctival mucin was purified by three sequential density gradient centrifugation steps. Immobilised mucin was probed with biotin-labelled bacteria isolated from different contact lens events and quantified by densitometry. Bacterial pili were identified by electron microscopy. The results indicate that purified ocular mucin consisted of a polydisperse high molecular weight population containing at least one species of goblet cell origin and was associated with a 97 kDa mucin-associated protein. Three pathogenic P. aeruginosa strains, Paer1 (57.5 +/- 10.8x10(6) CFU ml(-1); contact lens induced acute red eye (CLARE)), 6294 (127.0 +/- 4.7x10(6) CFU ml(-1); microbial keratitis) and Paer25 (60.5 +/- 11.3x10(6) CFU ml(-1); CLARE) exhibited a significantly higher level of adhesion to mucin than the negative control, E. coli (14.3 +/- 9.6x10(6) CFU ml(-1)) (p<0.005). The remaining P. aeruginosa isolates, Paer3 (asymptomatic patient), Paer12 (microbial keratitis) and ATCC 15442 (standard environmental strain) did not significantly differ in their mucin adhesion from the negative control. The majority of bacterial strains tested contained pili; thus differences in mucin adhesion observed could not be solely explained by pili status. In conclusion, P. aeruginosa isolates exhibit differential adhesion patterns to purified ocular mucin. It is proposed that more avid mucin-adhering strains are given the opportunity to adhere and subsequently penetrate the mucous layer of the tear film to initiate pathogenesis.     

Comparison of efficiency of intravitreal ceftazidime and intravitreal cefepime in the treatment of experimental Pseudomonas aeruginosa endophthalmitis

In this study, we evaluated the efficiency of cefepime in the treatment of experimental Pseudomonas aeruginosa endophthalmitis. We compared the findings with the standard dose of ceftazidime (1 mg/0.1 ml). Thirty-six New-Zealand White rabbits were divided into 6 equal groups and were treated with different methods (Group 1 = sham, Group 2 = 0.5 mg/0.1 ml cefepime, Group 3 = 1 mg/0.1 ml cefepime, Group 4 = 2 mg/0.1 ml cefepime, Group 5 = 1 mg/0.1 ml ceftazidime, Group 6 = control). The eyes of rabbits in each group were examined clinically on 1^st, 3^rd, and 6^th day of the experiment. At 6^th day, 0.1 ml vitreous humor aspirates were obtained and plated for quantification on the blood agar and the results were expressed as colony-forming unit/ml. Subsequently, the eyeballs were enucleated and the histopathological evaluation was performed. Our findings denoted beneficial effects of cefepime in treatment groups (especially, in Groups 3 and 4). Intravitreal cefepime may be an alternative drug in the treatment of P. aeruginosa endophthalmitis.