Comparative In Vitro Activity of Omadacycline against Dog and Cat Bite Wound Isolates

Omadacycline in treating community-based infections: a review and expert perspective

INTRODUCTION

Omadacycline is approved for the treatment of community-acquired bacterial pneumonia (CABP) and acute bacterial skin and soft tissue infection (ABSSSI). The integration of newer agents into clinical use involves understanding the nuances of clinical decision-making. This review will provide an in-depth focus on omadacycline in clinical practice.

AREAS COVERED

Literature review of omadacycline utilizing PubMed was performed to provide a comprehensive evaluation of omadacycline pharmacology, microbiology, registrational Phase 3 clinical trials, and post-marketing clinical studies. In addition, the immunomodulatory and other attributes of tetracycline class of antibiotics, of which omadacycline is a member, are reviewed, introducing the concept of antibiotic selection with attention to the bacterial pathogen and human host relationship.

EXPERT OPINION

Omadacycline builds upon the favorable attributes of tetracycline antibiotics and provides very reliable empiric coverage for both Staphylococcus aureus and Streptococcus spp. Clinicians require a more robust understanding of antibiotics, including omadacycline, in order to optimize patient outcomes, streamline care, and reduce medical costs.

The Development of Third-Generation Tetracycline Antibiotics and New Perspectives

The tetracycline antibiotic class has acquired new valuable members due to the optimisation of the chemical structure. The first modern tetracycline introduced into therapy was tigecycline, followed by omadacycline, eravacycline, and sarecycline (the third generation). Structural and physicochemical key elements which led to the discovery of modern tetracyclines are approached. Thus, several chemical subgroups are distinguished, such as glycylcyclines, aminomethylcyclines, and fluorocyclines, which have excellent development potential. The antibacterial spectrum comprises several resistant bacteria, including those resistant to old tetracyclines. Sarecycline, a narrow-spectrum tetracycline, is notable for being very effective against Cutinebacterium acnes. The mechanism of antibacterial action from the perspective of the new compound is approached. Several severe bacterial infections are treated with tigecycline, omadacycline, and eravacycline (with parenteral or oral formulations). In addition, sarecycline is very useful in treating acne vulgaris. Tetracyclines also have other non-antibiotic properties that require in-depth studies, such as the anti-inflammatory effect effect of sarecycline. The main side effects of modern tetracyclines are described in accordance with published clinical studies. Undoubtedly, this class of antibiotics continues to arouse the interest of researchers. As a result, new derivatives are developed and studied primarily for the antibiotic effect and other biological effects.

What we actually know about the pathogenicity of Bacteroides pyogenes

The aim of the study was to evaluate the pathogenic potential of Bacteroides pyogenes, rarely identified in clinical laboratories anaerobic bacteria. To increase the knowledge about this poorly understood anaerobic microorganism, the study also includes cases of infections described so far in the literature. Only the use of 16S rRNA sequencing and mass spectrometry technique allowed the identification of B. pyogenes from clinical specimens. We reported 13 severe human infections caused by B. pyogenes. Bacteria were cultured from the wound after biting by animals, chronic infections within the oral cavity, from patients with histologically or radiological proven osteomyelitis, surgical site infection, and from urine sample collected after a urological procedure. Most (9/13) of the patients required hospitalization. Almost 70% of them needed urgent admission via the emergency room. Two inpatients due to a life-threatening condition were admitted to the intensive care unit. Almost 50% of isolates were resistant to penicillin. All resistant to penicillin strains were isolated from skin and mucous membrane infections.

Oral flora of stray dogs and cats in Algeria: Pasteurella and other zoonotic bacteria

Background and Aim:

Knowledge of potentially pathogenic bacteria presents in the oral cavity of dogs and cats may be helpful in determining appropriate treatment for infected bite wounds. About 120.000 people are exposed to dog and cat bites every year in Algeria, but little is known about the dog and cat oral flora causing bite wound complications. The purpose of this study was to identify potential zoonotic bacteria from oral cavity of dogs and cats and to determine their susceptibility to antibiotics to contribute to the treatment of bite wound infection.

Materials and Methods:

Oral swabs from 100 stray dogs and 100 stray cats were collected and cultured in several media: Chocolate agar, MacConkey agar, and Mannitol Salt Agar. Bacterial isolates were identified using several commercial kits of the analytical profile index and tested for antibiotic susceptibility by disk diffusion method.

Results:

Overall, 185/200 (92.5%) dogs and cats carried zoonotic bacteria in their mouths, of which 55.13% (102/185) had at least two bacterial pathogens. 374 pathogenic strains belonging to 15 genera were isolated: Eleven were Gram-negative (Proteus, Pasteurella, Escherichia, Moraxella, Klebsiella, Acinetobacter, Enterobacter, Pseudomonas, Aeromonas, and NeisseriaHaemophilus) and four were Gram-positive (Staphylococcus, Streptococcus, and Corynebacterium, Bacillus). Fifty-one strains of Pasteurella were isolated from 44 carriers of Pasteurella (21 Pasteurella multocida, 21 Pasteurella pneumotropica, and 9 Pasteurella spp.). Pasteurella strains were tested for antibiotic resistance. Resistance to at least one drug was observed in 8 (15.68%) of Pasteurella isolates and two strains (3.92%) were found to be multidrug-resistant (to two or more drugs). Erythromycin, penicillin, and ampicillin were the antimicrobials to which the isolates showed greater resistance (7.84%, 5.88%, and 3.92%, respectively).

Conclusion:

To the best of our knowledge, this study is the first in Algeria to detect potential human pathogenic bacteria in the oral cavity of dogs and cats. It reveals that these animals have multiple zoonotic bacteria in their mouths including Pasteurella species, which may be multidrug-resistant.

Omadacycline: A Novel Oral and Intravenous Aminomethylcycline Antibiotic Agent

Omadacycline is a novel aminomethylcycline antibiotic developed as a once-daily, intravenous and oral treatment for acute bacterial skin and skin structure infection (ABSSSI) and community-acquired bacterial pneumonia (CABP). Omadacycline, a derivative of minocycline, has a chemical structure similar to tigecycline with an alkylaminomethyl group replacing the glycylamido group at the C-9 position of the D-ring of the tetracycline core. Similar to other tetracyclines, omadacycline inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit. Omadacycline possesses broad-spectrum antibacterial activity against Gram-positive and Gram-negative aerobic, anaerobic, and atypical bacteria. Omadacycline remains active against bacterial isolates possessing common tetracycline resistance mechanisms such as efflux pumps (e.g., TetK) and ribosomal protection proteins (e.g., TetM) as well as in the presence of resistance mechanisms to other antibiotic classes. The pharmacokinetics of omadacycline are best described by a linear, three-compartment model following a zero-order intravenous infusion or first-order oral administration with transit compartments to account for delayed absorption. Omadacycline has a volume of distribution (V_d) ranging from 190 to 204 L, a terminal elimination half-life (t_½) of 13.5-17.1 h, total clearance (CL_T) of 8.8-10.6 L/h, and protein binding of 21.3% in healthy subjects. Oral bioavailability of omadacycline is estimated to be 34.5%. A single oral dose of 300 mg (bioequivalent to 100 mg IV) of omadacycline administered to fasted subjects achieved a maximum plasma concentration (C_max) of 0.5-0.6 mg/L and an area under the plasma concentration-time curve from 0 to infinity (AUC_0-∞) of 9.6-11.9 mg h/L. The free plasma area under concentration-time curve divided by the minimum inhibitory concentration (i.e., fAUC_24h/MIC), has been established as the pharmacodynamic parameter predictive of omadacycline antibacterial efficacy. Several animal models including neutropenic murine lung infection, thigh infection, and intraperitoneal challenge model have documented the in vivo antibacterial efficacy of omadacycline. A phase II clinical trial on complicated skin and skin structure infection (cSSSI) and three phase III clinical trials on ABSSSI and CABP demonstrated the safety and efficacy of omadacycline. The phase III trials, OASIS-1 (ABSSSI), OASIS-2 (ABSSSI), and OPTIC (CABP), established non-inferiority of omadacycline to linezolid (OASIS-1, OASIS-2) and moxifloxacin (OPTIC), respectively. Omadacycline is currently approved by the FDA for use in treatment of ABSSSI and CABP. Phase II clinical trials involving patients with acute cystitis and acute pyelonephritis are in progress. Mild, transient gastrointestinal events are the predominant adverse effects associated with use of omadacycline. Based on clinical trial data to date, the adverse effect profile of omadacycline is similar to studied comparators, linezolid and moxifloxacin. Unlike tigecycline and eravacycline, omadacycline has an oral formulation that allows for step-down therapy from the intravenous formulation, potentially facilitating earlier hospital discharge, outpatient therapy, and cost savings. Omadacycline has a potential role as part of an antimicrobial stewardship program in the treatment of patients with infections caused by antibiotic-resistant and multidrug-resistant Gram-positive [including methicillin-resistant Staphylococcus aureus (MRSA)] and Gram-negative pathogens.

Omadacycline: A Novel Tetracycline Derivative With Oral and Intravenous Formulations

Omadacycline, an aminomethylcycline, is a novel member of the tetracycline class of antibiotics. It has received approval by the US Food and Drug Administration for the treatment of community-acquired bacterial pneumonia and acute bacterial skin and skin structure infections, and is available in both oral and intravenous formulations. It is also being evaluated in clinical trials for the treatment of cystitis and pyelonephritis. The omadacycline molecule was designed to overcome tetracycline resistance and has broad-spectrum activity that includes gram-positive bacteria, gram-negative bacteria, anaerobes, atypicals, and other drug-resistant strains, like methicillin-resistant Staphylococcus aureus, as well as Yersinia pestis and Bacillus anthracis, organisms of biodefense interest. Omadacycline has minimal drug-drug pharmacokinetic interactions and a favorable safety profile, with the most common adverse events being gastrointestinal symptoms.

Omadacycline: a novel aminomethylcycline

Tetracyclines have come a long way since they became available almost seven decades ago, with numerous enhancements allowing new agents to overcome bacterial mechanisms of resistance. However, these enhancements come with toxicities and pharmacokinetic disadvantages such as the gastrointestinal side-effects and poor oral bioavailability seen with the glycylcylcines. Omadacycline, a new and improved tetracycline, has demonstrated a broad spectrum of in vitro activity, has oral and intravenous formulations, improved safety compared to glycylcyclines, as well as clinical efficacy and safety for two types of infections: acute bacterial skin and skin structure infections and community-acquired bacterial pneumonia. This review will summarize salient points about its pharmacologic properties, available clinical efficacy, and safety data and omadacycline's place in therapy.

Omadacycline: A New Tetracycline Antibiotic

OBJECTIVE

To review the chemistry, pharmacology, microbiology, pharmacokinetics, pharmacodynamics, clinical efficacy, tolerability, dosage, and administration of omadacycline, a new tetracycline antibiotic.

DATA SOURCES

A literature search through PubMed, Google Scholar, and clinicaltrials.gov was conducted (2008 to October 2018) using the search terms omadacycline and PTK-0796. Abstracts presented at recent conferences, prescribing information and information from the FDA and the manufacturer's website were reviewed.

STUDY SELECTION AND DATA EXTRACTION

Preclinical data and published phase 1, 2, and 3 studies were evaluated.

DATA SYNTHESIS

Omadacycline displays in vitro activity against a wide range of bacteria. Clinical trials have shown that omadacycline is noninferior to linezolid for the treatment of acute bacterial skin and skin structure infections (ABSSSI) and noninferior to moxifloxacin for the treatment of community-acquired bacterial pneumonia (CABP). A loading dose of 200 mg intravenously (IV) once or 100 mg IV twice or 450 mg orally once is recommended followed by a maintenance dose of 100 mg IV or 300 mg orally once daily. No dosage adjustment is needed in patients with renal or hepatic impairment. Omadacycline is well tolerated, with nausea being a common adverse effect, but is associated with food and drug interactions. Relevance to Patient Care and Clinical Practice: Omadacycline is active against staphylococci, including methicillin-resistant strains, and streptococci, including tetracycline-resistant strains, as well as atypical bacteria. Omadacycline provides clinicians with an additional parenteral and oral option for the treatment of adults with ABSSSI and CABP.

CONCLUSION

Omadacycline is an alternative treatment option for ABSSSI and CABP.

Omadacycline Enters the Ring: A New Antimicrobial Contender

Omadacycline is a novel aminomethylcycline approved for the treatment of community‐acquired bacterial pneumonia and acute bacterial skin and skin structure infections. This article reviews existing data pertaining to the biochemistry, mechanism of action, pharmacokinetics/pharmacodynamics, in vitro activity, and current progress with omadacycline in clinical trials. Omadacycline inhibits protein synthesis by binding to the 30S subunit of the bacterial ribosome at the tetracycline‐binding site with an affinity similar to glycylcyclines. It is able to bypass older tetracycline resistance mechanisms and demonstrates activity against bacterial strains that are tetracycline resistant. In addition, omadacycline displays broad‐spectrum activity against gram‐positive organisms (including methicillin‐resistant Staphylococcus aureus and vancomycin‐resistant enterococci), gram‐negative organisms, atypical organisms, and anaerobes. It has been evaluated against infections in adults both intravenously and orally. Dosage adjustments are not required for patients with renal impairment. Omadacycline displays a comparable efficacy and safety profile to standard‐of‐care agents, with the most common side effects observed being gastrointestinal. Currently available data for omadacycline suggest that this is a promising agent added to our antimicrobial armamentarium.

Thinking Outside the Box-Novel Antibacterials To Tackle the Resistance Crisis

The public view on antibiotics as reliable medicines changed when reports about "resistant superbugs" appeared in the news. While reasons for this resistance development are easily spotted, solutions for re-establishing effective antibiotics are still in their infancy. This Review encompasses several aspects of the antibiotic development pipeline from very early strategies to mature drugs. An interdisciplinary overview is given of methods suitable for mining novel antibiotics and strategies discussed to unravel their modes of action. Select examples of antibiotics recently identified by using these platforms not only illustrate the efficiency of these measures, but also highlight promising clinical candidates with therapeutic potential. Furthermore, the concept of molecules that disarm pathogens by addressing gatekeepers of virulence will be covered. The Review concludes with an evaluation of antibacterials currently in clinical development. Overall, this Review aims to connect select innovative antimicrobial approaches to stimulate interdisciplinary partnerships between chemists from academia and industry.

β-lactam/β-lactamase inhibitor combinations: an update

Antibiotic resistance caused by β-lactamase production continues to present a growing challenge to the efficacy of β-lactams and their role as the most important class of clinically used antibiotics. In response to this threat however, only a handful of β-lactamase inhibitors have been introduced to the market over the past thirty years. The first-generation β-lactamase inhibitors (clavulanic acid, sulbactam and tazobactam) are all β-lactam derivatives and work primarily by inactivating class A and some class C serine β-lactamases. The newer generations of β-lactamase inhibitors including avibactam and vaborbactam are based on non-β-lactam structures and their spectrum of inhibition is extended to KPC as an important class A carbapenemase. Despite these advances several class D and virtually all important class B β-lactamases are resistant to existing inhibitors. The present review provides an overview of recent FDA-approved β-lactam/β-lactamase inhibitor combinations as well as an update on research efforts aimed at the discovery and development of novel β-lactamase inhibitors.