Bacterial flora in relation to cataract extraction. II. Peroperative flora

Area of Science:

• Ophthalmology
• Microbiology
• Surgical Infections

Background:

• Cataract extraction is a common procedure with a risk of surgical site infections.
• Understanding the peroperative microbial flora is crucial for preventing postoperative complications.

Purpose of the Study:

• To investigate the peroperative microbial flora in patients undergoing cataract extraction.
• To assess the efficacy of a single preoperative dose of oxytetracycline-polymyxin B on bacterial reduction.
• To identify the sources of bacterial contamination, particularly Staphylococcus aureus, during surgery.

Main Methods:

• Bacterial cultures were taken from the conjunctiva and wound sites of 499 patients before and after cataract surgery.
• Preoperative flora was compared with intraoperative and postoperative cultures.
• The impact of a single preoperative dose of oxytetracycline-polymyxin B, administered 18 hours prior to surgery, was evaluated.
• The origin of isolated Staphylococcus aureus strains was traced to various patient and environmental sources.

Main Results:

• A single preoperative dose of oxytetracycline-polymyxin B significantly reduced bacterial incidence at the time of surgery.
• Despite antibiotic application, 92% of conjunctivas harbored microorganisms immediately before operation.
• Bacterial contamination was found in 61% of wound sites at the conclusion of surgery.
• The majority of Staphylococcus aureus strains originated from the patient's own preoperative conjunctival flora.

Conclusions:

• While preoperative antibiotics reduce bacterial load, conjunctival contamination remains high before cataract surgery.
• Wound site contamination post-surgery is frequent, primarily due to endogenous microbial sources.
• Targeting the patient's own flora, particularly Staphylococcus aureus from the conjunctiva, is critical for reducing surgical site infections.