In vitro antibacterial activity of moxifloxacin against hospital isolates: a multicentre study

Moxifloxacin releasing intraocular implant based on a cross-linked hyaluronic acid membrane

Intraocular antibiotic delivery is an important technique to prevent bacterial infection after ophthalmic surgery, such as cataract surgery. Conventional drug delivery methods, such as antibiotic eye drops, have limitations for intraocular drug delivery due to the intrinsic barrier effect of the cornea. Therefore, frequent instillation of antibiotic eyedrops is necessary to reach a sufficient bactericidal concentration inside the eye. In this study, an intraocular implant, MXF-HA, that combines hyaluronic acid (HA) and moxifloxacin (MXF) was developed to increase the efficiency of intraocular drug delivery after surgery. MXF-HA is manufactured as a thin, transparent, yellow-tinted membrane. When inserted into the eye in a dry state, MXF-HA is naturally hydrated and settles in the eye, and the MXF contained therein is delivered by hydrolysis of the polymer over time. It was confirmed through in vivo experiments that MXF delivery was maintained in the anterior chamber of the eye at a concentration sufficient to inhibit Pseudomonas aeruginosa and Staphylococcus aureus for more than 5 days after implantation. These results suggest that MXF-HA can be utilized as a potential drug delivery method for the prevention and treatment of bacterial infections after ophthalmic surgery.

Intravitreal moxifloxacin injections in acute post-cataract surgery endophthalmitis: Efficacy and safety

Purpose

The aim of this study was to evaluate the efficacy and safety of intravitreal moxifloxacin injections in the treatment of acute post-cataract surgery endophthalmitis with visual acuity equal to or greater than hand movements.

Methods

Fifty two patients with post-cataract surgery endophthalmitis who presented within 6 weeks with visual acuity equal to or greater than hand movements received two intravitreal moxifloxacin injections 48 h apart. Patients with prior history of ocular disease or treatment were excluded. Patients were followed up to 3 months either for resolution of endophthalmitis or worsening of disease. Number of patients who achieved visual acuity equal to or better than 20/40 and 20/200 at the third-month follow-up visit were compared with the number of patients at presentation, using Chi-square test. In addition, pretreatment LogMAR visual acuity at the time of presentation was compared with posttreatment visual acuity at end of third month using paired t test.

Results

Fifty (96.15%) patients showed complete resolution of endophthalmitis while three patients required vitrectomy. Forty-one (78.85%) and 49 (94.23%) patients achieved visual acuity equal to or better than 20/40 and 20/200, respectively, at the third-month follow-up visit as compared to eight (15.38%) and 13 (25%) patients, respectively, at presentation (P < 0.05). In addition, mean LogMAR visual acuity at the time of presentation was 0.755 which improved to 0.307 at the third-month follow-up visit (P < 0.05). None of the patients developed hypersensitivity reactions to intravitreal moxifloxacin.

Conclusion

Intravitreal moxifloxacin injections showed promising results in acute post-cataract surgery endophthalmitis.

Delafloxacin for the Treatment of Acute Bacterial Skin and Skin Structure Infections

Objective: To review the microbiological activity, safety, and efficacy of the new fluoroquinolone delafloxacin for the treatment of acute bacterial skin and skin structure infections (ABSSSIs). Data Sources: A PubMed search from 1945 to September 2018 was done using the terms delafloxacin, acute bacterial skin and skin structure infections, skin and soft tissue infections, and fluoroquinolone. Additional sources include the Food and Drug Administration website, ClinicalTrials.gov, and the Melinta Therapeutics website. Study Selection and Data Extraction: The literature search was limited to those published in the English language and included in vitro and human studies that evaluated microbiological coverage, pharmacokinetics, pharmacodynamics, safety, and/or efficacy. Data Synthesis: Delafloxacin is a new fluoroquinolone with a unique structure for its class that covers both methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas. This new antibiotic has demonstrated noninferiority to vancomycin plus aztreonam for the treatment of ABSSSIs in both an intravenous-only regimen and an intravenous to an oral regimen. Relevance to Patient Care and Clinical Practice: ABSSSIs are infections that are most often caused by Staphylococcus and represent one of the most common types of hospital infections. MRSA represents about half of all staphylococcal skin infections, and along with gram-negative infections, increase the rates of patient morbidity and health care costs. Delafloxacin is an additional treatment option that covers both of these types of microorganisms. Conclusions: Delafloxacin is a safe and effective treatment option for ABSSSIs, particularly in those with polymicrobial infections and those with MRSA.

Antibiotic resistance in microbial keratitis: ten-year experience of corneal scrapes in the United Kingdom

PURPOSE

To determine the scale of antibiotic resistance in microbial keratitis in East Kent, United Kingdom.

DESIGN

Retrospective, observational case series.

PARTICIPANTS

Corneal scrapes over a 10-year period to December 2008 were identified using the local microbiology database, which provided culture results and antibiotic sensitivity-resistance profiles.

TESTING

Isolate sensitivity to chloramphenicol, cefuroxime, gentamicin, and ciprofloxacin was determined by microdilution using the Microscan System (Siemens Diagnostics, Dearfield, IL).

MAIN OUTCOME MEASURES

Isolates were graded as sensitive, intermediate, or resistant to the tested antibiotics, with minimal inhibitory concentrations interpreted against breakpoints from the Clinical and Laboratory Standards Institute.

RESULTS

There were 476 scrapes from 440 patients (female, 57.6%; mean age, 53.5 years). All samples were cultured. Culture was positive in 163 samples (34.2%), growing 172 organisms. Bacterial keratitis accounted for 162 isolates (94.2%), of which 99 (61.1%) were gram-negative. There was a general increase in the number of gram-negative isolates with time (P=0.003). In vitro testing showed widespread gram-negative resistance to chloramphenicol (74.1%), with reducing sensitivity over the study period (P=0.004). There was 97.3% sensitivity to combination gentamicin and cefuroxime, and 94.4% sensitivity to ciprofloxacin. Ciprofloxacin resistance was found in 8 (17.0%) of 47 gram-positive isolates tested, with no trend toward increasing resistance.

CONCLUSIONS

This study has documented the highest levels of gram-negative keratitis in any open retrospective survey to date and highlights a trend of increasing gram-negative infection. We have demonstrated reducing chloramphenicol sensitivity, with high sensitivity to combination gentamicin and cefuroxime, as well as ciprofloxacin. Gram-positive fluoroquinolone resistance was higher than previously reported in the United Kingdom, but showed no evidence of increasing resistance. Second-generation fluoroquinolone monotherapy remains the recommended empirical treatment in microbial keratitis in the United Kingdom, and a change to fourth-generation compounds is not advised. Continued testing is essential to monitor for increasing resistance.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

What are the most appropriate antibiotics for the treatment of acute exacerbation of chronic obstructive pulmonary disease? A therapeutic outcomes model

OBJECTIVES

To predict the clinical efficacy of several antimicrobials in the treatment of patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD).

METHODS

A probability model (therapeutic outcomes model) was used to predict the likelihood of clinical success with particular antimicrobial agents in the treatment of patients with AECOPD, both in those clinically diagnosed (total patients with an AECOPD diagnosis regardless of the cause) and in those with bacterial AECOPD. The model took into account the following variables: (i) the proportion of patients with a clinical diagnosis of AECOPD and non-bacterial disease; (ii) likelihood of spontaneous resolution of a non-bacterial infection; (iii) prevalence of subcauses (different bacterial species) in bacterial AECOPD; (iv) rates of spontaneous resolution of bacterial AECOPD; and (v) antimicrobial efficacy of each antibiotic against each bacterial species (susceptibility based on PK/PD breakpoints).

RESULTS

Fluoroquinolones (levofloxacin, ciprofloxacin and moxifloxacin), a new third-generation oral cephalosporin (cefditoren) and high doses of amoxicillin/clavulanate were the antimicrobials with the highest predicted clinical efficacy both in mild-moderate AECOPD and in severe AECOPD (rates of 89.2% to 90.5% and 80.3% to 88.1%, respectively), whereas cefaclor, azithromycin, erythromycin and clarithromycin had the lowest predicted clinical efficacy (rates of 79.1% to 81.3% and 51.8% to 55.6% for mild-moderate and severe AECOPD, respectively), which was not much higher than that predicted for placebo (73.6% and 45.5%, respectively).

CONCLUSIONS

According to our model, fluoroquinolones (levofloxacin, ciprofloxacin and moxifloxacin), cefditoren and amoxicillin/clavulanate are the most appropriate antibiotics for the treatment of patients with AECOPD in terms of predicted clinical efficacy, with wide differences with respect to other antibiotics commonly used in the treatment of these patients, such as clarithromycin and azithromycin.

Levofloxacin for the treatment of community-acquired pneumonia

New respiratory fluoroquinolones (FQs), such as levofloxacin, offer many improved qualities over older agents, such as ciprofloxacin. These include retaining excellent Gram-negative bacilli activity, with improved Gram-positive activity. New FQ-like levofloxacin possesses greater bioavailabilty and a longer serum half-life compared with ciprofloxacin, allowing for once-daily dosing, which may improve patient adherence. The high bioavailability of levofloxacin allows for rapid step-down from intravenous administration to oral therapy, minimizing unnecessary hospitalization, which may decrease costs and improve patient quality of life. Levofloxacin has been evaluated for the treatment of community-acquired pneumonia (CAP) in numerous randomized clinical trials. Most published studies have used the 500 mg dose, although more recent studies have investigated the 750 mg dose once daily. These trials demonstrate that levofloxacin is effective and safe for the treatment of CAP, displaying relatively mild adverse effects that are more or less comparable with ciprofloxacin. Levofloxacin has much to offer in terms of bacterial eradication, including for resistant respiratory pathogens. However, ciprofloxacin-resistant organisms are becoming more prevalent so prudence must be exercised when prescribing this agent.

Susceptibility Testing of Clinical Isolates of Pseudomonas aeruginosa to Levofloxacin, Moxifloxacin, and Gatifloxacin as a Guide to Treating Pseudomonas Ocular Infections

PURPOSE

Pseudomonas aeruginosa ocular infections most frequently originate from an environmental source; successful treatment with various ocular antibiotics is well established. However, emergence of resistant clones to available antibiotics poses a real threat to successful treatment. The purpose of this study was to evaluate the antibiotic susceptibilities of 100 random clinical isolates of P. aeruginosa to levofloxacin, moxifloxacin, and gatifloxacin, potential agents for the treatment of ocular infections caused by this microorganism.

METHODS

One hundred consecutive strains of P. aeruginosa were isolated from clinical specimens submitted to the clinical microbiology hospital laboratory. Duplicate isolates were not included. The minimum inhibitory concentrations (MICs) of these isolates were determined by using Etests, performed according to the manufacturer's instructions. American Type Culture Collection (ATCC) strains of Escherichia coli, P. aeruginosa, and Staphylococcus aureus served as reference controls.

RESULTS

Although most isolates were susceptible to levofloxacin, moxifloxacin, and gatifloxacin and the MICs were not significantly different, significant numbers were resistant. The standardized controls rendered expected MICs. The susceptibility of the isolates varied with regard to source, and resistant strains showed increased resistance.

CONCLUSIONS

Based on the data, the treatment of ocular infections caused by P. aeruginosa with levofloxacin, moxifloxacin, and gatifloxacin still has a high likelihood of success. However, six of the isolates collected were resistant to all three of the fluoroquinolones tested. Based on the data, clinicians must be aware that clinical resistance can occur even with the newer fluoroquinolones.

Overview of the Potency of Moxifloxacin Ophthalmic Solution 0.5% (VIGAMOX®)

Antibiotics have been the mainstay of therapy for infectious diseases since their origins in the 1940s. As microorganisms changed and resistance developed, more advanced antibiotics were ultimately needed to provide adequate coverage and spectrum. By selecting optimal antibiotics and dosing regimens, clinicians can avoid treatment failures and adverse events and can help prevent the emergence of further antibiotic resistance. The fourth-generation ophthalmic fluoroquinolones include moxifloxacin (VIGAMOX, Alcon Laboratories, Inc., Fort Worth, TX) and gatifloxacin (Zymar, Allergan, Irvine, CA), and they are now approved for the treatment of bacterial conjunctivitis. This review highlights four scientific methods that compare and rank antibiotic potencies and predict their clinical efficacy and their propensity to develop resistance: 1) in vitro assay for minimum inhibitory concentrations, 2) in vivo models for pharmacokinetic and pharamacodynamic properties, 3) therapeutic index or inhibitory quotient, and 4) in vitro assay for mutant prevention concentration. The fourth-generation ophthalmic fluoroquinolones perform well in these assays. Both antibiotics have better in vitro activity against gram-positive bacteria than ciprofloxacin or ofloxacin. Moxifloxacin penetrates better into ocular tissues than gatifloxacin and older fluoroquinolones; in vitro activity of moxifloxacin and gatifloxacin against gram-negative bacteria is similar to that of older fluoroquinolones. Moxifloxacin also has better mutant prevention characteristics than other fluoroquinolones. These findings support the use of the newer fluoroquinolones for the prevention and treatment of serious ophthalmic infections (e.g., keratitis, endophthalmitis) caused by susceptible bacteria.