[Chronic carriers of pathogen conjunctival bacteria. Possible risks in cataract surgery]

To ascertain the frequency and characteristics of chronic carriers of conjunctival pathogen bacteria among patients undergoing cataract surgery in our hospital, to allow the design of studies of their postsurgical endophthalmitis risk.

Retrospective study of the preoperative conjunctival flora of 784 patients operated on for cataracts in both eyes, in two operations separated by 213 days (SD 170), from November 1993 to December 1997. Results of both cultures for each patient were obtained from the Laboratory cataract preoperative database, by means of an auxiliary utility in dBASE-III-PLUS program. The preoperative bacteria in both surgeries were compared and the patients having the same pathogen bacteria (all except Staphylococcus coagulase negative and Corynebacterium sp.) were identified. The mean values and standard deviations were calculated using Epiinfo 6.04, and the Chi2 test was carried out using Excel 97.

The conjunctival flora stemming from the first preoperative culture of the 784 patients were statistically similar to those of our reference population. The pathogen bacteria decreased in the second preoperative culture; especially the Streptococcus Pneumoniae and Haemophilus sp. frequencies (p<0.05). The same pathogen was isolated in both cultures of 31 patients among the 784 who entered the study, Staphylococcus Aureus and Proteus Mirabilis being the most frequent colonizers. The mean age of those carriers was higher than the mean age of the reference population (p<0.01).

3.95% of our patients awaiting cataract surgery are usual conjunctival carriers of certain pathogen bacteria; this finding is associated with the age of the patients and possibly with some pre-existing diseases.