Eyeworld

EW RESIDENTS 68 January 2017 Conversely, the number of eyes from which P. acnes was isolated increased after antibiotic administration in both groups. The 1-week group in- creased from 27/53 pre-administra- tion to 38/53 after antibiotics, and the 1-month group increased from 22/50 pre-antibiotics to 36/50 after completion of antibiotics. Similarly to S. epidermis the rates of P. acnes returned to baseline at 3 months post-treatment. The effects of antibiotic therapy on minimum inhibitory concentra- tion (MIC) of levofloxacin against S. epidermis demonstrate that MIC increases with longer duration of antibiotic therapy. In the 1-week study group, the MIC increased from 0.58 μg/mL at pre-administration to 5.62 μg/mL after completion of antibiotic therapy. In the 1-month study group, the MIC increased from 0.93 μg/mL at pre-administration to 13.94 μg/mL after completion of 1 month of antibiotic therapy. MIC declined at 3 and 6 months after completion of antibiotic therapy in both groups, however, at 3 months, the MIC in the 1-month study group was significantly greater than that in the 1-week study group. The study also examined the susceptibility pattern of S. epidermis isolated from the eyes of patients in both groups. In the 1-week group, the percentage of bacteria suscepti- ble to levofloxacin decreased from 73.6% pre-antibiotics to 20.2% at completion of antibiotic therapy and then rose to 38.5% at 3 months post-antibiotics. In the 1-month group, susceptibility decreased from 63% pre-antibiotics to 0% at com- pletion of antibiotic therapy and then rose to 19.3% at 3 months after completion of therapy. These results indicate that susceptibility decreases with longer duration of antibiotic therapy. The authors conclude that dif- ferences in the duration of periop- erative antibiotic therapy results in alterations of both MIC and susceptibility rates of S. epidermis in the conjunctival flora. This effect seems to be more pronounced with increased duration of therapy as greater resistance is evident in the 1-month group at all post-therapy time points. The results of this study suggest that a shorter duration anti- biotic therapy may be considered to reduce the development of antibi- otic resistance. Since the current study demonstrates alterations in bacterial MIC and susceptibility with prolonged use of antibiotics, the and cultured. Enrichment cultures were also performed on conjunctival swabs during which the samples were grown for 2 weeks prior to culturing and antibiotic susceptibil- ity testing. Antibiotic susceptibility testing of the isolated bacteria was performed using specialized oph- thalmic antibacterial susceptibility measurement plates. The first table in the paper de- scribes the bacterial composition of the conjunctival flora and changes associated with antibiotic adminis- tration. A total of 103 patients were included in the study: 53 partici- pants in the 1-week group and 50 in the 1-month group. Prior to levo- floxacin administration, baseline cultures of eyes in the 1-week and 1-month groups produced 92 and 75 strains of bacteria, respectively. After completion of postoperative antibi- otics, there were 53 bacterial strains in the 1-week group and 47 in the 1-month group. At 1 and 3 months after the completion of antibiotics, the eyes in the 1-week group had 81 and 77 strains, respectively, and the 1-month group had 79 and 72 strains, respectively. The number of eyes from which gram-positive cocci were isolated decreased in both groups after antibiotic administra- tion (41/53 eyes down to 12/53 eyes in the 1-week group after a 1-week course of antibiotics and 35/50 down to 9/50 in the 1-month group after a 1-month course of antibiot- ics). At 3 months after administra- tion in both groups, the number of eyes from which gram-positive cocci were isolated was again at pre-antibi- otic administration levels. Focus was placed on S. epidermis because coagulase negative staphylo- cocci are most commonly implicated in postoperative endophthalmitis. At completion of antibiotic therapy in both the 1-week and 1-month study groups, there was a signifi- cant decrease in the presence of S. epidermis. Specifically, in the 1-week study group, S. epidermis isolates decreased from 35/53 eyes prior to drug administration to 9/53 eyes after completion of antibiotics. Sim- ilar results were seen in the 1-month group, with rates dropping from 29/50 eyes to 7/50 eyes. However, within 3 months after completion of antibiotics, the rate of S. epidermis isolation returned to the pre-antibi- otic levels. In the 1-week group at 3 and 6 months, rates were 27/49 and 25/46 eyes, respectively. In the 1-month study group, rates were 28/47 and 14/41 eyes, respectively. question arose whether differences in antibiotic duration affect clinical outcomes. The authors pointed out that the small sample size was insuf- ficient to demonstrate superiority between the two groups. It is inter- esting to note that despite differ- ences in prophylactic antibiotic use between ophthalmologists in Japan and the U.S., literature demonstrates similar rates of endophthalmitis in the two countries. 1, 11 A few questions arose in review- ing the article. First, the information on patient selection and demo- graphics is limited. Second, it would be useful if the authors included more specific information on comor- bidities present in study participants and if patients who had received systemic antibiotics were excluded. Third, the authors mention that patients were eligible for inclusion if their "normal conjunctival bacte- rial flora" had been tested in the 2 months immediately prior to sur- gery without defining "normal" or what exclusion criteria existed if this wasn't the case. Although beyond the authors' control, it is interesting to note that their exclusion criteria included the use of topical ophthal- mic antibiotics within the 3 months preceding the study, however, their results demonstrated that conjunc- tival flora remain altered for at least 6 months after topical antibiotic therapy. A notable strength of the study is the design of the susceptibility testing. The authors thoughtfully used a method of drug susceptibility testing that includes antibiotics and drug concentrations more relevant Review continued from page 66 An investigation of the effect of the administration period with perioperative topical levofloxacin on normal conjunctival bacterial flora Ryohei Nejima, MD, Kimiya Shimizu, MD, PhD, Takashi Ono, MD, Yukari Noguchi, COT, Akiko Yagi, BS, Takuya Iwasaki, MD, PhD, Nobuyuki Shoji, MD, PhD, and Kazunori Miyata, MD, PhD J Cataract Refract Surg. 2017;43(1). Article in press Purpose: We investigated the effect of long- and short-term post- cataract surgery antibiotic therapy on the drug-resistance profile of normal conjunctival bacterial flora. Setting: Miyata Eye Hospital, Miyazaki, Japan. Subjects: Patients, aged ≥20 years, who underwent cataract surgery between January and March 2015 were eligible. Design: A single-center, randomized, parallel controlled non-blinded study. Methods: Levofloxacin (LVFX) ophthalmic solution (1.5%) was administered from 3 days before surgery. The patients (n=104) were randomly assigned to postoperative 1-week and 1-month (Po1W and Po1M, respectively) groups according to postoperative administration duration. Conjunctival sacs were scraped for bacterial culturing before administration (pre), 1 week after surgery (1 W), at the completion of administration (0 D), and 1, 3, and 6 months after administration completion (1 M, 3 M, and 6 M, respectively). We assessed the bacterial culture growth and minimum inhibitory concentrations (MICs) of LVFX against recovered strains of Staphylococcus epidermidis and Propionibacterium acnes. Results: MICs of LVFX against Staphylococcus epidermidis increased during LVFX 1.5% administration compared to pre levels in both groups and then declined after administration completion. However, by 3 months, the MICs of the Po1M group were approximately twice those of the Po1W group. Antibiotic susceptibility at pre, 0 D, and 3 M was 73.6%, 20.2%, and 38.5%, respectively, in the Po1W group compared with 63.0%, 0.0%, and 19.3%, respectively, in the Po1M group. The results indicate that from 0 D to 3 M, the susceptible strains were approximately 20% lower in the Po1M than in the Po1W group. Conclusions: Administration duration of perioperative LVFX 1.5% influenced the MICs and susceptibility of S. epidermidis isolated from the conjunctival sac.

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