Robert Yoshimori

Outpatient Topical Use of Povidone-iodine in Preparing the Eye for Surgery

Povidone-iodine 5% solution placed on the eye immediately before ophthalmic surgery within the preoperative preparation significantly reduces the conjunctival bacterial flora. In 40 patients undergoing ophthalmic surgery, the authors compared the outpatient use of povidone-iodine for 3 days before surgery with a 3-day course of a combination antibiotic ophthalmic solution (Neosporin) placed on the other eye. All patients also received topical povidone-iodine on the operating table directly preceding surgery. Cultures taken just before preparation of the operative field showed a similar reduction of bacteria by each regimen. Cultures taken after preparation but before commencement of surgery showed a further reduction for both regimens, but more for eyes previously treated with the antibiotic (P less than 0.02). To minimize the conjunctival bacterial flora before surgery, the authors continue to recommend instillation of a broad-spectrum antibiotic for 3 days before surgery, followed by application of povidone-iodine solution to the eye immediately before surgery within the preoperative preparation.

Efficacy of topical povidone-iodine during the first week after ophthalmic surgery.

PURPOSE In the first postoperative day, povidone-iodine ophthalmic solution prevents an increase in conjunctival bacterial colony-forming units and decreases the species compared with antibiotic. We sought to determine whether these beneficial effects of povidone-iodine could be sustained during the first postoperative week. METHODS In 42 eyes of 35 consecutive patients, one or two drops of either a broad-spectrum antibiotic (polymyxin B sulfate-neomycin sulfate-gramicidin) or povidone-iodine 1.25% to 2.5% were placed in the treated eye or eyes at the conclusion of surgery and three times daily during the first postoperative week. Bacterial cultures were taken from both eyes at the end of surgery before instillation of either of the eyedrops and again 1 week later. Twenty-eight untreated eyes served as a control group. RESULTS During the first postoperative week, the number of colony-forming units and species increased in both treatment groups. Relative to the control group, both medications effectively reduced the mean number of colony-forming units at 1 week (P < .02), but their effects on colony-forming units did not significantly differ from each other (80 +/- 290 for the povidone-iodine-treated eyes and 75 +/- 90 for the antibiotic-treated eyes). At 1 week, the species count increased 281% in the antibiotic group but only 106% in the povidone-iodine group. Compared to the control group, eyes that received povidone-iodine had a significantly lower species count (P = .0097). CONCLUSION Povidone-iodine ophthalmic solution is an alternative to postoperative topical antibiotics because of its effectiveness in controlling conjunctival bacterial colony-forming units and species, its relatively low cost, and its availability.

Povidone-iodine for Ophthalmia Neonatorum Prophylaxis

PURPOSE The agents currently used to prevent ophthalmia neonatorum are less than optimal, with reports indicating evidence of bacterial resistance, ineffectiveness, and toxicity. Povidone-iodine ophthalmic solution, which has been shown to be effective in the preoperative preparation of the eye, generates no resistance, is an effective antimicrobial agent, and has low toxicity. We evaluated the effectiveness and safety of povidone-iodine for ophthalmia neonatorum prophylaxis. METHODS A bacterial culture was taken from the conjunctiva of each eye of 100 infants within 30 minutes of birth. A drop of 2.5% povidone-iodine solution was then placed on one eye, while the other eye received either one drop of silver nitrate 1% ophthalmic solution or 0.5% erythromycin ointment. Conjunctival bacterial cultures were again taken two to four hours after birth. At each culture and at 24 hours after birth, the eyes were examined for toxic changes. To measure the effectiveness of the medications, the number of bacterial colony-forming units and species from each culture was compared. RESULTS All three agents significantly reduced the number of colony-forming units, but povidone-iodine caused the most significant decrease. The number of species was reduced significantly by povidone-iodine (P = .00051) and silver nitrate (P = .007), with povidone-iodine yielding the most significant decrease. Erythromycin did not significantly reduce the number of species. Silver nitrate demonstrated more ocular toxicity at the 24-hour determination point than did either of the other two medications (P < .001). CONCLUSIONS Povidone-iodine 2.5% ophthalmic solution is an effective antibacterial agent on the conjunctiva of newborns and causes less toxicity than silver nitrate.

Antimicrobial therapy of postpartum endomyometritis: II. Prospective, randomized trial of mezlocillin versus ampicillin

Seventy patients with postpartum endomyometritis were treated with either intravenous mezlocillin (16 gm/day) or ampicillin (8 gm/day) in a prospective, randomized, double-blind comparison. Endocervical dilatation was routinely performed. Clindamycin (2 gm/day) was added if patients failed to improve within 48 hours of beginning therapy. Pretreatment clinical and microbiologic profiles were comparable in the two groups. Bacteremia was documented in 21 patients (30%). Anaerobic cocci and Bacteroides spp. (non-B. fragilis) comprised 19 of 29 (65%) blood isolates. Thirty of 33 mezlocillin-treated patients (91%) and 30 of 37 ampicillin-treated patients (81%) responded to initial therapy (P greater than 0.4). Resolution was noted after the addition of clindamycin in all ten nonresponders; two of these patients also required surgical wound debridement. Objective parameters of clinical response were not significantly different in the two treatment groups. Side effects of mezlocillin therapy were minimal. We conclude that mezlocillin and ampicillin are equally effective and safe for therapy of postpartum endomyometritis. That mezlocillin was not superior to ampicillin, despite expanded activity against B. fragilis and members of Enterobacteriaceae, suggests that these pathogens are less important than was previously considered in postpartum endomyometritis.

Importance of Medium in Demonstrating Penicillin Tolerance by Group B Streptococci

A total of 30 clinical isolates of group B streptococci were studied for penicillin tolerance in vitro. Minimal inhibitory and bactericidal concentrations of penicillin were determined simultaneously in three test media which have been used for group B streptococci, tryptose phosphate, Mueller-Hinton, and Todd-Hewitt broths, using a logarithmic-phase inoculum of 105 colony-forming units per ml. Minimal inhibitory concentrations in the three media did not differ significantly. However, minimal bactericidal concentrations were significantly higher in tryptose phosphate broth (mean, 1.04 μg/ml) than in Mueller-Hinton broth (0.22 μg/ml) or Todd-Hewitt broth (0.15 μg/ml). Similarly, ratios of minimal bactericidal to minimal inhibitory concentrations were significantly greater in tryptose phosphate broth than in Mueller-Hinton or Todd-Hewitt broth. After incubation in tryptose phosphate broth for an additional 24 h, the minimal bactericidal concentration consistently fell to levels which were only twice or equal to the minimal inhibitory concentration. This study illustrates the importance of the medium in the demonstration of penicillin tolerance and of controlling laboratory variables in the susceptibility testing of group B streptococci with penicillin.

Postoperative neurosurgical infections due to bacillus species.

The cases of 2 patients with postoperative ventriculitis due to Bacillus species bacteria are presented. Bacillus licheniformis was isolated from one patient following removal of an intraventricular meningioma, and Bacillus cereus from another patient following placement of a ventriculoperitoneal shunt. Both isolates were resistant to a variety of antibiotics, but both were sensitive to gentamicin and chloramphenicol. These cases emphasize several points; (a) Bacillus species, usually thought to be nonpathogenic, may produce intracranial infections; (2) species identification is important for epidemiological purposes and for the selection of appropriate chemotherapeutic agents; and (3) in cases of suspected ventriculitis, chloramphenicol or gentamicin should be considered for Grams staining revealing gram-positive bacilli. In addition, we recommend that when planning antibiotic prophylactic regimens, consideration should be given to including one of these agents to assure coverage of Bacillus species.

Source of the conjunctival bacterial flora at birth and implications for ophthalmia neonatorum prophylaxis

To understand better the source of conjunctival bacteria in neonates, we studied 106 infants immediately after birth before any eyedrops were applied. The 50 infants delivered by cesarean section had significantly fewer species (0.50 +/- 0.85 vs 1.84 +/- 1.33) and colony forming units (272 +/- 1,019 vs 1,790 +/- 3,779) cultured per subject than the 56 infants delivered vaginally. In infants delivered by cesarean section within three hours of membrane rupture, 24 of 30 (80%) of the conjunctival cultures were sterile, while the rest bore a few cutaneous bacteria (0.23 +/- 0.50 species and 2 +/- 9 colony forming units per subject). The conjunctivae of infants delivered vaginally bore significantly more bacteria characteristic of vaginal flora: microaerophilic as Lactobacillus or truly anaerobic as Bifidobacterium. Neonates delivered by cesarean section more than three hours after membrane rupture showed a bacteriologic flora mixture quantitatively and qualitatively midway between those two groups. Infants delivered by cesarean section within three hours of membrane rupture may not need prophylactic eyedrops because of the type and scarcity of conjunctival bacteria.

Bacterial flora of the conjunctiva at birth.

In the largest study to date of bacterial flora in newborns, we cultured the conjunctivae of 100 infants within 15 minutes after vaginal delivery and before any antimicrobial agents had been applied to the eye. All cultures were intensively analyzed for anaerobic and aerobic bacteria. By far the largest group of bacteria isolated were microaerophilic, such as Lactobacillus species and diphtheroids, accounting for 46.8% of positive cultures and 62.3% of all bacteria isolated. The second largest group were true anaerobic bacteria, such as Bacteroides and Propionibacterium species. The smallest group were aerobic bacteria. This incidence of non-aerobic bacteria in the conjunctiva of newborns is the highest reported to date. Our finding should alert clinicians to consider non-aerobic, especially microaerophilic, bacteria in the differential diagnosis of ophthalmia neonatorum. The high rate of supposedly sterile cultures reported in other studies may be explained at least partially by improper isolation of non-aerobic bacteria.