In vivo antimicrobial activity of 0.6% povidone-iodine eye drops in patients undergoing intravitreal injections: a prospective study

Antimicrobials and antiseptics: Lowering effect on ocular surface bacterial flora - A systematic review

Topical antimicrobials and antiseptics are used perioperatively to reduce the ocular surface bacteria flora (OSBF) that are involved in the development of post-operative infectious complications. However, their effectiveness is still a controversial topic. This systematic review, performed according to the PRISMA guidelines and registered in PROSPERO, aims to provide an overview of the efficacy of the agents currently used in peri-cataract surgery and -intravitreal injections (IVI) in lowering the OSBF. Although effective in lowering OSBF, perioperative topical antimicrobials are associated with the risk of resistance development, with no obvious additional benefit compared with topical antisepsis. Conversely, the effectiveness of topical antiseptics before cataract surgery and IVI is strongly supported. Based on the available evidence, perioperative antimicrobials are not recommended, whereas the perioperative use of antiseptics is strongly recommended as prophylactic treatment for lowering the infection due to OSBF. Post-operative antimicrobials may be considered in eyes at higher risk for infection.

Prophylaxis of Ocular Infection in the Setting of Intraocular Surgery: Implications for Clinical Practice and Risk Management

In this review we discuss the role of intraocular surgery preoperative prophylaxis. The correct choice of antimicrobial drug is variable in each surgical setting, according to the available strengths of evidence, the anatomical district involved, and the type of procedure. In the ophthalmic surgical field, there has been a progressive shift from antibiotic formulations, which are known to cause antibiotic resistance, to a new class of antiseptic compounds, which proved to be effective not only against bacteria, but also against fungi, protozoa, and viruses. Among these, povidone-iodine (PVI) is a water-soluble polymer that can form a complex with iodine, and the perioperative application of PVI 5-10% eye drop for 3 min is the gold standard for infection prophylaxis. A new formulation of 0.6% PVI eye drop is a new option for infection prophylaxis in the days before surgery. Chlorhexidine is a biguanide compound, which is a valid alternative with a good safety and efficacy profile and is the antiseptic of choice in patients with iodine allergy. New compounds that are currently being studied include polyhexamethylene biguanide (PHMB), picloxydine, ozone, hypochlorous acid (HOCl), and Biosecur. PHMB is a biguanide polymer that was found to be more effective than PVI in in vitro studies for reducing microorganisms and extending the duration of antisepsis, but to date, there are no formulations available on the market for preoperative ocular surgery in which it is present as main ingredient. Ozone is a molecule with oxidizing effect, which showed interesting preliminary results but is not effective against virus, Staphylococcus aureus and Candida albicans. HOCl has a natural bactericidal propriety but its applicability to prophylaxis of ocular infection in the setting of ocular surgery is not established. Biosecur is a non-toxic organic alcohol-free compound that exhibited bactericidal and fungicidal effect versus all common microorganisms and is currently available as an ocular spray.

Ten-Year Analysis of Pathogenic Factors and Etiological Characteristics of Endophthalmitis from a Tertiary Eye Center in North China

Purpose

To describe the etiology and spectrum of isolated pathogens in endophthalmitis over 10 years from an ophthalmic hospital in North China and report their antimicrobial susceptibilities.

Patients and Methods

The data covered the patients with endophthalmitis treated at Qingdao Eye Hospital from January 2011 to December 2020. Patients’ medical history, pathogenic factors, bacterial and fungal culture results of intraocular specimens, and in vitro drug sensitivity test results were assessed.

Results

A total of 524 cases were counted in this study. Exogenous endophthalmitis was the main component, accounting for 94.66%, of which 49.62% of eyes had a history of ophthalmic trauma, intraocular surgery in 26.72% and suppurative keratitis in 17.37%. By comparison, endogenous endophthalmitis was found in only 5.34% of eyes. Among the 292 strains of pathogenic organisms obtained by co-culture, gram-positive bacteria accounted for 64.04%, with Staphylococcus epidermidis as the predominant pathogen (29.45%). Gram-positive cocci were identified in 76.77% of eyes with traumatic endophthalmitis, while 53.70% of keratitis-associated endophthalmitis was caused by fungi. The high susceptibility of bacteria to vancomycin (77.78%~98.33%) supported its continued use as empirical treatment. Among the fluoroquinolones, gram-positive cocci showed a higher susceptibility to gatifloxacin (94.83%), while there was a significant decrease to levofloxacin (51.67%). Gram-negative bacteria were less sensitive to cephalosporins (45.95%~66.67%) than fluoroquinolones (68.42%~78.05%) and aminoglycosides (75.00%~78.05%). Fungal susceptibilities to voriconazole and amphotericin B were 90.16% and 70.31% respectively. More than half of the 11 antibiotics were observed to exhibit a trend of reduced susceptibility.

Conclusion

Ophthalmic trauma was the primary pathogenic factor of endophthalmitis. Gram-positive cocci were the most common pathogens of traumatic and postoperative endophthalmitis, while suppurative keratitis-associated endophthalmitis often resulted from fungal pathogens. Levofloxacin as the preferred antibiotic in the perioperative period and cephalosporin as the first-line drug for the treatment of empiric endophthalmitis need to be vigilant.

Efficacy of Three Povidone Iodine Formulations against Cutibacterium acnes Assessed through In Vitro Studies: A Preliminary Study

Cutibacterium acnes (C. acnes, formerly known as Propionibacterium acnes) is the major causative agent of prosthetic joint infections (PJI). Treatment of PJI with antibiotics is difficult due to antibiotic resistance and adverse side effects on patients’ health. Proper disinfection of the surgical site using a variety of povidone iodine formulations could prevent C. acnes infection. In the current study, the efficacy of the three povidone iodine (PVP-I) formulations, viz: PVP-I 10% dermic solution, PVP-I 5% alcoholic solution and PVP-I 4% scrub, was tested against C. acnes, in vitro, in the presence of interfering substances mimicking soiling conditions. C. acnes strain ATCC 6919 was used to test the bactericidal activity of the povidone iodine formulations according to the modified dilution-neutralization method described in French Norm EN standard 13727. A 3-log reduction in the bacterial cell count in 60 s was considered to be significant. The results showed that under experimental conditions, the three PVP-I formulations displayed bactericidal activity against the micro-organism, Cutibacterium acnes, and that the lowest concentration of povidone-iodine active against C. acnes was 0.4%. These results are encouraging as PVP-I offers a low-cost and efficient method of disinfection.

The Role of Topical Povidone-Iodine in the Management of Infectious Keratitis: A Pilot Study

The aim of this prospective explorative study was to evaluate the safety and the effectiveness of topical polyvinylpyrrolidone-iodine (PVP-I) administered during the time-to-results period for pathogen identification and susceptibility testing in patients with infectious keratitis (IK). A corneal swab (CS) for antimicrobial evaluation was performed at enrollment (T0) and topical 0.66%-PVP-I was administered until the laboratory results were available (T1). Ulcer and infiltrate areas and infiltrate depths were compared between T0 and T1 (i.e., time-to-result period). Patients were then shifted to a specific antimicrobial therapy and followed up until resolution of their infiltrates (Tlast-TL). Twenty-five eyes were enrolled, and none showed clinical worsening leading to protocol withdrawal. At T1, ulcer and infiltrate areas showed significant improvement in Gram-positive IK (n = 13–52%; p = 0.027 and p = 0.019, respectively), remained stable in fungal IK (n = 5–20%; both p = 0.98) and increased in those with Gram-negative bacteria (n = 4–16%; p = 0.58 and p = 0.27). Eyes with negative cultures (n = 3–12%) showed complete resolution at T1 and did not initiate any additional antimicrobial therapy. The administration of 0.66% PVP-I during the time-to-result period seems to be a safe strategy in patients with IK while often sparing broad-spectrum antimicrobial agents. In addition, it showed to be effective in eyes with a Gram-positive bacterial infection.