Bacterial flora in relation to cataract extraction. III. Postoperative flora

Area of Science:

• Ophthalmology
• Microbiology
• Infectious Diseases

Background:

• Cataract surgery involves risks of postoperative ocular infections.
• Understanding the dynamic changes in conjunctival flora post-surgery is crucial for infection prevention.
• Previous studies (Fahmy et al. 1975b, c) established baseline conjunctival flora before and during surgery.

Purpose of the Study:

• To investigate the alterations in conjunctival flora on the 4th and 7th days after cataract surgery.
• To compare postoperative conjunctival flora with pre-operative and intra-operative findings.
• To identify the sources of Staphylococcus aureus isolated postoperatively.

Main Methods:

• Culturing conjunctival flora from 499 cataract surgery patients on postoperative days 4 and 7.
• Comparing results with prior cultures taken on admission and during surgery.
• Analyzing the origin of Staphylococcus aureus strains through strain similarity and patient/staff nasal cultures.

Main Results:

• Following antibiotic administration, Staphylococcus albus incidence increased to pre-admission levels by postoperative day 4.
• Corynebacteria and gram-negative bacilli also showed increased incidence, though not reaching pre-admission levels.
• Staphylococcus aureus strains isolated postoperatively primarily matched pre-operative conjunctival flora, with some traced to patient or nurse nares; ward air, eye drops, and ointments were not significant sources.

Conclusions:

• Postoperative antibiotic regimens can lead to shifts in conjunctival bacterial populations.
• The patient's own flora is the predominant source of Staphylococcus aureus following cataract surgery.
• Environmental factors like ward air and topical medications appear to be minor contributors to S. aureus contamination.