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Study: ofloxacin more effective with 3 days of treatment than 1 hour
Researchers also suggest that 3 days of preop topical ofloxacin may be as effective in reducing bacteria as povidone iodine prep immediately before surgery.
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NEW ORLEANS — Applying topical ofloxacin preoperatively for 3 days, as opposed to 1 hour before surgery, was found to be more effective in preventing the growth of bacteria in conjunctival isolates, according to data presented here.
The study also suggested that 3 days of topical ofloxacin was as effective as povidone iodine prep in reducing the bacterial count in the operative field immediately before surgery. This may offer an alternative course for patients allergic to iodine, one of the study authors suggested.
“Previous studies have shown that antibiotics, combined with povidone iodine, are effective in eliminating bacteria from the conjunctiva,” Christopher N. Ta, MD, said here at the American Academy of Ophthalmology meeting. “However, there has been a paucity of data on the optimal dosing regimen of topical antibiotics.”
To gain scientific evidence, Dr. Ta and his colleagues compared the incidence of bacterial flora in the conjunctiva during surgery in patients who were treated with Ocuflox (ofloxacin, Allergan) for 3 days preoperatively and those treated with ofloxacin immediately before surgery.
“We found that the application of ofloxacin 3 days prior to surgery, rather than on the day of, is more effective in reducing the number of positive conjunctival bacteria cultures in the perioperative period,” he said.
Study design
The prospective study included 92 eyes of 89 cataract surgery candidates. Pa tients were randomized into two groups, and cataract surgery was performed.
The control group of 48 eyes received three drops of topical ofloxacin every 5 minutes for 1 hour before cataract surgery. The study group of 44 eyes received topical ofloxacin four times a day for 3 days prior to cataract surgery.
Patients in the study group also received the identical ofloxacin treatment as the control group 1 hour before surgery. All patients were prepped with 5% povidone iodine immediately before surgery.
A series of cultures were obtained before and after surgery from both groups. The first sample (T-0) was taken 5 days before surgery. The second culture (T-1) was taken 1 hour before surgery, before topical ofloxacin application. The third sample (T-2) was obtained after topical ofloxacin was ap plied but before povidone iodine was applied. A fourth sample (T-3) was taken immediately before surgery, after topical ofloxacin and povidone iodine were applied. The final sample (T-4) was taken immediately after surgery was completed. The cultures were then inoculated into blood, chocolate agar and thioglycolate broth, Dr. Ta said.
Results
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Researchers found the amount of bacteria in both groups was reduced with the presence of both topical ofloxacin and povidone iodine. However, the percentage of positive cultures was significantly lower in the group that received 3 days of ofloxacin than in the control group at time points T-2, T-3 and T-4.
“At T-2 there were 50% positive cultures in the control group compared to 25% in the study group. At T-3 it was 42% versus 19%, and at T-4 it was 34% versus 14%,” Dr. Ta said. Using the two-tailed chi-square test, the P value was less than or equal to .05 for all these time points, he said.
According to Dr. Ta, after the initial culture sample was taken at 5 days prior to surgery, both the study group and the control group had more than 100 colony-forming units in each blood agar sample. After 3 days of ofloxacin treatment, the maximum number of colony-forming units dropped to four and one at time points T-1 and T-2 respectively, while the control group still had more than 100 colony-forming units, Dr. Ta said.
After eyes were scrubbed with povidone iodine, both the study and the control samples showed only a few colony-forming units, “due to the overwhelming antiseptic effect of povidone iodine,” Dr. Ta said.
However, there was a notable difference between the groups once surgery was performed. Using the Mann-Whitney U-Test, the researchers found a statistically significant difference in the T-4 samples of the blood agar media. The study group had significantly fewer bacteria.
The results also suggested that topical ofloxacin for 3 days before surgery may be as effective in reducing bacteria count as povidone iodine applied immediately before surgery, Dr. Ta said. He compared time point T-2 in the study group, after 3 days of ofloxacin treatment but before iodine prep, with T-3 in the control group, after iodine prep. At T-2, the study group had a lower percentage of positive cultures, a lower mean and a lower number of colony-forming units than the control group had at T-3, even though the eyes in the control group had received iodine prep.
A symbiotic effect
According to Eric Donnenfeld, MD, results from Dr. Ta’s study provide “new and interesting” information for preventing endophthalmitis. He said that by reducing the maximum inoculation of bacteria, endophthalmitis may be prevented.
Dr. Donnenfeld added, “This experimental data shows a symbiotic effect of combining antibiotic and povidone iodine to achieve better bacterial eradication at several different time intervals during the perioperative period — an element not previously documented.”
For Your Information:
- Christopher N. Ta, MD, can be reached at Stanford University Medical Center, Department of Ophthalmology, 900 Blake Wilson Drive, Palo Alto, CA 94305; (650) 498-4791; fax: (650) 498-4222. Dr. Ta has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
- Eric D. Donnenfeld, MD, can be reached at Ryan Medical Arts Bldg., 2000 North Village Ave., Suite 402, Rockville Centre, NY 11570; (516) 766-2519; fax: (516) 766-3414. Dr. Donnenfeld has no direct financial interest in the products mentioned in this article. He is a paid consultant for Allergan.
- Allergan, manufacturers of Ocuflox, can be reached at 2525 Dupont Drive, Irvine, CA 92612; (800) 433-8871; fax: (714) 246-5913; Web site: www.allergan.com.