Microbiological profile of ozenoxacin

In vitro activity of ozenoxacin against Staphylococcus aureus and Streptococcus pyogenes clinical isolates recovered in a worldwide multicentre study (2020-2022)

Objectives

We performed a multicentre study (2020-2022) to compare the in vitro activity of ozenoxacin and comparator agents against Staphylococcus aureus and Streptococcus pyogenes clinical isolates from skin and soft-tissue infections (SSTI).

Methods

A total of 1725 isolates (1454 S. aureus and 271 S. pyogenes) were collected in 10 centres from eight countries between January 2020 and December 2022. Antimicrobial susceptibility testing was determined (microdilution-SENSITITRE). Results were interpreted following European Committee on Antimicrobial Susceptibility Testing (EUCAST) 2023 (clinical breakpoints, ECOFF) and CLSI criteria.

Results

Ozenoxacin exhibited high in vitro activity against S. aureus (MIC50/90 = 0.002/0.12 mg/L) and S. pyogenes (MIC50/90 = 0.015/0.03 mg/L), inhibiting 99% of the isolates at MIC ≤ 0.5 mg/L and at MIC ≤ 0.06, respectively. The most active comparators against S. aureus were retapamulin (MIC90 = 0.12 mg/L), fusidic acid (MIC90 = 0.25 mg/L) and mupirocin (MIC90 = 0.5 mg/L); and against S. pyogenes were retapamulin (MIC90 = 0.03 mg/L), clindamycin (MIC90 = 0.12 mg/L) and mupirocin (MIC90 = 0.25 mg/L). Ciprofloxacin and methicillin resistant rates for S. aureus were 31.3% (455/1454) and 41% (598/1454), respectively. Additionally, 62% (373/598) of the MRSA were also ciprofloxacin non-susceptible, whereas only 10% (23/271) of the MSSA were ciprofloxacin resistant. Ozenoxacin was more active against ciprofloxacin-susceptible S. aureus than against ciprofloxacin-resistant isolates, and showed a slightly higher MIC in MRSA isolates than in MSSA. However, ozenoxacin activity was comparable in both ciprofloxacin-resistant MSSA and MRSA subsets. On the other hand, ozenoxacin had similar activity in ciprofloxacin-susceptible and resistant S. pyogenes isolates.

Conclusions

Ozenoxacin is a potent antimicrobial agent of topic use against Gram-positive bacteria causing SSTI, including MRSA isolates non-susceptible to ciprofloxacin.

Ideal Features of Topical Antibiotic Therapy for the Treatment of Impetigo: An Italian Expert Consensus Report

Background

A group of Italian experts in impetigo medical care sought to define 10 statements to describe the ideal characteristics of the best local antibiotic treatments, and to provide relevant information re- garding their appropriate use and prescription that should be considered in clinical practice for impetigo management.

Objective

A group of Italian experts in impetigo medical care sought to define 10 statements to describe the ideal characteristics of the best local antibiotic treatments, and to provide relevant information regarding their appropriate use and prescription that should be considered in clinical practice for impetigo management.

Methods

A consensus on ideal features of antibiotic therapy for the treatment of impetigo was appraised by an online Delphi-based method, based on a panel of 61 infectious disease specialists, pediatricians, and dermatologists coordinated by a scientific committee of 5 experts specializing in impetigo management.

Results

Full or very high consensus was reached on the 10 statements identified to describe the characteristics of the best hypothetic antibiotic therapy for impetigo together with indications for appropriate antibiotics use.

Conclusions

Several criteria have to be considered when selecting topical antibacterial therapy for impetigo. Beyond efficacy and safety, antimicrobial susceptibility and pharmacological characteristics of the agent are essential points. Formulation of the antimicrobial product is fundamental, as well as patient and caregiver preference, to facilitate therapeutic adherence, to achieve the infection control, and to obtain the best benefit from treatment (Curr Ther Res Clin Exp. 2023; 84:XXXXXX).

Antimicrobial activity of ozenoxacin and other antimicrobials against Staphylococcus aureus strains isolated from clinical skin specimens in Japan in 2019 and 2020

Skin infections caused by methicillin-resistant Staphylococcus aureus (MRSA) and the spread of antimicrobial resistance are a major problem in Japan. Here, we investigated the susceptibility of S. aureus clinical isolates to ozenoxacin (OZNX), a topical antimicrobial approved for superficial skin infection treatment in Japan. Susceptibility to OZNX was measured in 110 skin-derived methicillin-susceptible S. aureus (MSSA) and 130 MRSA strains isolated in 2019 and 2020 in Japan. The broth microdilution method was performed, and results were analyzed according to the Clinical and Laboratory Standard Institute (M07 and M100) guidelines. The results were compared with those of other antimicrobials used against S. aureus. The minimum inhibitory concentrations (MIC)90 of OZNX for MSSA and MRSA were 0.12 and 0.25 μg/mL, respectively, indicating that OZNX exhibited the same or stronger antibacterial activity than that of the other antimicrobials tested, such as nadifloxacin, fucidic acid, and gentamicin. No strains exhibited reduced OZNX susceptibility. Notably, a low MIC of OZNX was observed even for strains with reduced susceptibility to nadifloxacin, a similar quinolone-based topical antimicrobial. OZNX is a highly potent antimicrobial used in Japan for superficial skin infections caused by S. aureus, such as impetigo contagiosa and related diseases.

Uptake of Ozenoxacin and Other Quinolones in Gram-Positive Bacteria

The big problem of antimicrobial resistance is that it requires great efforts in the design of improved drugs which can quickly reach their target of action. Studies of antibiotic uptake and interaction with their target it is a key factor in this important challenge. We investigated the accumulation of ozenoxacin (OZN), moxifloxacin (MOX), levofloxacin (LVX), and ciprofloxacin (CIP) into the bacterial cells of 5 species, including Staphylococcus aureus (SA4-149), Staphylococcus epidermidis (SEP7602), Streptococcus pyogenes (SPY165), Streptococcus agalactiae (SAG146), and Enterococcus faecium (EF897) previously characterized.The concentration of quinolone uptake was estimated by agar disc-diffusion bioassay. Furthermore, we determined the inhibitory concentrations 50 (IC50) of OZN, MOX, LVX, and CIP against type II topoisomerases from S. aureus.The accumulation of OZN inside the bacterial cell was superior in comparison to MOX, LVX, and CIP in all tested species. The accumulation of OZN inside the bacterial cell was superior in comparison to MOX, LVX, and CIP in all tested species. The rapid penetration of OZN into the cell was reflected during the first minute of exposure with antibiotic values between 190 and 447 ng/mg (dry weight) of bacteria in all strains. Moreover, OZN showed the greatest inhibitory activity among the quinolones tested for both DNA gyrase and topoisomerase IV isolated from S. aureus with IC50 values of 10 and 0.5 mg/L, respectively. OZN intracellular concentration was significantly higher than that of MOX, LVX and CIP. All of these features may explain the higher in vitro activity of OZN compared to the other tested quinolones.

In vitro activity and resistance rates of topical antimicrobials fusidic acid, mupirocin and ozenoxacin against skin and soft tissue infection pathogens obtained across Canada (CANWARD 2007-18)

BACKGROUND

Current antimicrobial susceptibility/resistance data versus skin and soft tissue infection (SSTI) pathogens help to guide empirical treatment using topical antimicrobials.

OBJECTIVES

To assess the in vitro activity and resistance rates of fusidic acid, mupirocin, ozenoxacin and comparator agents against pathogens isolated from patients with SSTIs in Canada.

METHODS

SSTI isolates of MSSA (n = 422), MRSA (n = 283) and Streptococcus pyogenes (n = 46) obtained from CANWARD 2007-18 were tested using CLSI broth microdilution. Fusidic acid low-level resistance was defined as an MIC of ≥2 mg/L and high-level resistance as an MIC ≥512 mg/L. Mupirocin high-level resistance was defined as an MIC ≥512 mg/L and low-level resistance was an MIC of 2-256 mg/L.

RESULTS

Low-level and high-level fusidic acid resistance in MSSA was 10.9% and 1.7%, respectively. Low-level and high-level fusidic acid resistance in MRSA was 10.6% and 3.5%, respectively. High-level mupirocin resistance was identified in 1.4% of MSSA and 14.1% of MRSA, respectively. Versus MSSA, ozenoxacin demonstrated MIC50 and MIC90 of 0.004 and 0.25 mg/L, respectively. Against MRSA, ozenoxacin inhibited all isolates at an MIC of ≤0.5 mg/L, including isolates with ciprofloxacin MICs >2 mg/L, clarithromycin-resistant, clindamycin-resistant, high-level fusidic acid-resistant and high-level mupirocin-resistant isolates.

CONCLUSIONS

We conclude that fusidic acid low-level resistance exceeded 10% for both MSSA and MRSA while fusidic acid high-level resistance was ≤3.5%. Mupirocin high-level resistance exceeded 10% in MRSA. Ozenoxacin is active versus SSTI pathogens including MRSA resistant to fluoroquinolones, macrolides, clindamycin, fusidic acid and mupirocin.

Emerging Treatment Strategies for Impetigo in Endemic and Nonendemic Settings: A Systematic Review

PURPOSE

Impetigo affects approximately 162 million children worldwide at any given time. Lack of consensus on the most effective treatment strategy for impetigo and increasing antibiotic resistance continue to drive research into newer and alternative treatment options. We conducted a systematic review to assess the effectiveness of new treatments for impetigo in endemic and nonendemic settings.

METHODS

We searched PubMed, MEDLINE, CINAHL, Web of Science, and Embase via Scopus for studies that explored treatments for bullous, nonbullous, primary, and secondary impetigo published between August 1, 2011, and February 29, 2020. We also searched online trial registries and hand-searched the reference lists of the included studies. We used the revised Cochrane risk of bias (version 2.0) tool for randomized trials and the National Heart, Lung, and Blood Institute for nonrandomized uncontrolled studies to assess the risk of bias.

FINDINGS

We included 10 studies that involved 6651 participants and reported on 9 treatments in the final analysis. Most clinical trials targeted nonbullous impetigo or did not specify this. The risk of bias varied among the studies. In nonendemic settings, ozenoxacin 1% cream appeared to have the strongest evidence base compared with retapamulin and a new minocycline formulation. In endemic settings, oral co-trimoxazole and benzathine benzylpenicillin G injection were equally effective in the treatment of severe impetigo. Mass drug administration intervention emerged as a promising public health strategy to reduce the prevalence of impetigo in endemic settings.

IMPLICATIONS

This review highlights the limited research into new drugs used for the treatment of impetigo in endemic and nonendemic settings. Limited recent evidence supports the use of topical ozenoxacin or retapamulin for impetigo treatment in nonendemic settings, whereas systemic antibiotics and the mass drug administration strategy have evidence for use in endemic settings. Given the troubling increase in resistance to existing treatments, there is a clear need to ensure the judicious use of antibiotics and to develop new treatments and alternative strategies; this is particularly important in endemic settings. PROSPERO identifier: CRD42020173042.

New Antibiotics for the Treatment of Acute Bacterial Skin and Soft Tissue Infections in Pediatrics

Acute bacterial skin and soft tissue infections (aSSTIs) are a large group of diseases that can involve exclusively the skin or also the underlying subcutaneous tissues, fascia, or muscles. Despite differences in the localization and severity, all these diseases are due mainly to Gram-positive bacteria, especially Staphylococcus aureus and Streptococcus pyogenes. aSSTI incidence increased considerably in the early years of this century due to the emergence and diffusion of community-acquired methicillin-resistant S. aureus (CA-MRSA). Despite the availability of antibiotics effective against CA-MRSA, problems of resistance to these drugs and risks of significant adverse events have emerged. In this paper, the present knowledge on the potential role new antibiotics for the treatment of pediatric aSSTIs is discussed. The most recent molecules that have been licensed for the treatment of aSSTIs include ozenoxacin (OZ), ceftaroline fosamil (CF), dalbavancin (DA), oritavancin (OR), tedizolid (TD), delafloxacin (DL), and omadacycline (OM). However, only OZ and CF have been licensed for use in children with aSSTIs, although the superiority of these antibiotics to those routinely used for the treatment of aSSTIs should be further demonstrated. Waiting for additional studies, OZ and CF should be prescribed for aSSTI treatment in the presence of the potential failure of old molecules.