Prevalence and antibiotic susceptibility of bacteria isolated in patients affected with blepharitis in a tertiary eye centre in Spain.

Purpose: To describe which bacteria can be found on lid margins in patients affected with blepharitis, to show their antibiotic susceptibility pattern, and to evaluate the antibiotic resistance trend of coagulase-negative Staphylococcus through time.

Materials And Methods: Consecutive cases of 198 eyes affected with blepharitis between 2012 and 2018 were reviewed. A sample was collected by rubbing a swab against the base of the eyelashes of both the eyes of all patients. The samples were inoculated in blood agar and chocolate agar. The susceptibility of the identified bacteria to common antibiotics was tested. In addition, the antibiotic susceptibility pattern of coagulase-negative Staphylococcus detected from year 2016 to 2018 was compared with that of 4 years before.

Results: The most common isolated bacterium was coagulase-negative Staphylococcus (89%) and Staphylococcus aureus (28%). Coagulase-negative Staphylococcus showed highest susceptibility to vancomycin (100%), neomycin (94%) and chloramphenicol (91%). Coagulase-negative Staphylococcus and Staphylococcus aureus were the most resistant to penicillin and erythromycin (resistance in 92%, 91% for coagulase-negative Staphylococcus, 86% and 43% of eyes for Staphylococcus aureus). Corynebacterium was resistant to oxacillin and erythromycin. Streptococcus viridans showed resistance to gentamycin and tobramycin. Moraxella was susceptible to most antibiotics. Bacillus was resistant to oxacillin. The antibiotic resistance trend of coagulase-negative Staphylococcus showed that the resistance to rifampicin increased through the years 2012-2018.

Conclusion: Coagulase-negative Staphylococcus and Staphylococcus aureus were the most isolated bacteria in patients affected by blepharitis in our tertiary eye centre. Both bacteria were resistant to erythromycin. Through the years, it seems that coagulase-negative Staphylococcus gained resistance to penicillin, erythromycin, ciprofloxacin and rifampicin.