The monobactams

Understanding resistance acquisition by Pseudomonas aeruginosa and possible pharmacological approaches in palliating its pathogenesis

Pseudomonas aeruginosa can utilize various virulence factors necessary for host infection and persistence. These virulence factors include pyocyanin, proteases, exotoxins, 2-heptyl-4-hydroxyquinoline N-oxide (HQNO), phospholipases, and siderophores that enable the bacteria to cause severe infections in immunocompromised individuals. P. aeruginosa falls into the category of nosocomial pathogens that are typically resistant to available antibiotics and therapeutic approaches. P. aeruginosa bio-film formation is a major concern in hospitals because it can cause chronic infection and increase the risk of mortality. Therefore, the development of new strategies to disrupt biofilm formation and improve antibiotic efficacy for the treatment of P. aeruginosa infections is crucial. Anti-biofilm and anti-quorum sensing (QS) activity can be viewed as an anti-virulence approach to control the infectious nature of P. aeruginosa. Inhibition of QS and biofilm formation can be achieved through pharmacological approaches such as phytochemicals and essential oils, which have shown promising results in laboratory studies. A regulatory protein called LasR plays a key role in QS signaling to coordinate gene expression. Designing an antagonist molecule that mimics the natural autoinducer might be the best approach for LasR inhibition. Here we reviewed the mechanism behind antibiotic resistance and alternative approaches to combat the pathogenicity of P. aeruginosa.

Impact of Antibiotics as Waste, Physical, Chemical, and Enzymatical Degradation: Use of Laccases

The first traces of Tetracycline (TE) were detected in human skeletons from Sudan and Egypt, finding that it may be related to the diet of the time, the use of some dyes, and the use of soils loaded with microorganisms, such as Streptomyces spp., among other microorganisms capable of producing antibiotics. However, most people only recognise authors dating between 1904 and 1940, such as Ehrlich, Domagk, and Fleming. Antibiotics are the therapeutic option for countless infections treatment; unfortunately, they are the second most common group of drugs in wastewaters worldwide due to failures in industrial waste treatments (pharmaceutics, hospitals, senior residences) and their irrational use in humans and animals. The main antibiotics problem lies in delivered and non-prescribed human use, use in livestock as growth promoters, and crop cultivation as biocides (regulated activities that have not complied in some places). This practice has led to the toxicity of the environment as antibiotics generate eutrophication, water pollution, nutrient imbalance, and press antibiotic resistance. In addition, the removal of antibiotics is not a required process in global wastewater treatment standards. This review aims to raise awareness of the negative impact of antibiotics as residues and physical, chemical, and biological treatments for their degradation. We discuss the high cost of physical and chemical treatments, the risk of using chemicals that worsen the situation, and the fact that each antibiotic class can be transformed differently with each of these treatments and generate new compounds that could be more toxic than the original ones; also, we discuss the use of enzymes for antibiotic degradation, with emphasis on laccases.

The war against bacteria, from the past to present and beyond

INTRODUCTION

The human defense against microorganisms dates back to the ancient civilizations, with attempts to use substances from vegetal, animal, or inorganic origin to fight infections. Today, the emerging threat of multidrug-resistant bacteria highlights the consequences of antibiotics inappropriate use, and the urgent need for novel effective molecules.

METHODS AND MATERIALS

We extensively researched on more recent data within PubMed, Medline, Web of Science, Elsevier's EMBASE, Cochrane Review for the modern pharmacology in between 1987 - 2021. The historical evolution included a detailed analysis of past studies on the significance of medical applications in the ancient therapeutic field.

AREAS COVERED

We examined the history of antibiotics development and discovery, the most relevant biochemical aspects of their mode of action, and the biomolecular mechanisms conferring bacterial resistance to antibiotics.

EXPERT OPINION

The list of pathogens showing low sensitivity or full resistance to most currently available antibiotics is growing worldwide. Long after the 'golden age' of antibiotic discovery, the most novel molecules should be carefully reserved to treat serious bacterial infections of susceptible bacteria. A correct diagnostic and therapeutic procedure can slow down the spreading of nosocomial and community infections sustained by multidrug-resistant bacterial strains.

Multidrug Resistance (MDR) and Collateral Sensitivity in Bacteria, with Special Attention to Genetic and Evolutionary Aspects and to the Perspectives of Antimicrobial Peptides-A Review

Antibiotic poly-resistance (multidrug-, extreme-, and pan-drug resistance) is controlled by adaptive evolution. Darwinian and Lamarckian interpretations of resistance evolution are discussed. Arguments for, and against, pessimistic forecasts on a fatal “post-antibiotic era” are evaluated. In commensal niches, the appearance of a new antibiotic resistance often reduces fitness, but compensatory mutations may counteract this tendency. The appearance of new antibiotic resistance is frequently accompanied by a collateral sensitivity to other resistances. Organisms with an expanding open pan-genome, such as Acinetobacter baumannii, Pseudomonas aeruginosa, and Klebsiella pneumoniae, can withstand an increased number of resistances by exploiting their evolutionary plasticity and disseminating clonally or poly-clonally. Multidrug-resistant pathogen clones can become predominant under antibiotic stress conditions but, under the influence of negative frequency-dependent selection, are prevented from rising to dominance in a population in a commensal niche. Antimicrobial peptides have a great potential to combat multidrug resistance, since antibiotic-resistant bacteria have shown a high frequency of collateral sensitivity to antimicrobial peptides. In addition, the mobility patterns of antibiotic resistance, and antimicrobial peptide resistance, genes are completely different. The integron trade in commensal niches is fortunately limited by the species-specificity of resistance genes. Hence, we theorize that the suggested post-antibiotic era has not yet come, and indeed might never come.

Monocyclic β-Lactam: A Review on Synthesis and Potential Biological Activities of a Multitarget Core

A monocyclic ring in their structure characterizes monobactams, a subclass of β-lactam antibiotics. Many of these compounds have a bactericidal mechanism of action and acts as penicillin and cephalosporins, interfering with bacterial cell wall biosynthesis. The synthesis of novel β-lactams is an emerging area of organic synthesis research due to the problem of increasing bacterial resistance to existing β -lactam antibiotics, and, in this way, new compounds have been presented with several structural modifications, aiming to improve biological activities. Among the biological activities studied, the most outstanding are antibacterial, antitubercular, anticholesterolemic, anticancer, antiinflammatory, antiviral, and anti-enzymatic, among others. This review explores the vast number of works related to monocyclic β-lactams, compounds of great importance in scientific research.

Natural Products Containing a Nitrogen-Sulfur Bond

Only about 100 natural products are known to contain a nitrogen-sulfur (N-S) bond. This review thoroughly categorizes N-S bond-containing compounds by structural class. Information on biological source, biological activity, and biosynthesis is included, if known. We also review the role of N-S bond functional groups as post-translational modifications of amino acids in proteins and peptides, emphasizing their role in the metabolism of the cell.

Aztreonam (for inhalation solution) for the treatment of chronic lung infections in patients with cystic fibrosis: an evidence-based review

Cystic fibrosis (CF) is a genetic disease caused by abnormal chloride transport across cellular membranes. In the respiratory tract, this molecular defect causes obstruction of the airways by mucus and chronic endobronchial infection. The majority of patients suffer early death from chronic respiratory disease. Pseudomonas aeruginosa is the predominant chronic airway pathogen in older children and adults with CF and is associated with worse outcomes. However, overall survival in CF has been greatly improved in recent decades due in large part to the aggressive treatment of chronic infections such as P. aeruginosa. While intravenous and oral antibiotics are commonly used in the management of CF respiratory infections, inhaled anti-infective therapies offer the benefit of delivering the drug directly to the site of infection and avoiding potential toxicities associated with systemic absorption. Aztreonam lysine (AZLI) has recently been developed as an inhaled antibiotic for chronic use in CF patients with endobronchial P. aeruginosa infection. This paper reviews background data and the clinical studies which contributed to AZLI’s formal FDA approval and growing role in the management of CF pulmonary disease.

Successful treatment of Pasteurella multocida meningitis with aztreonam

This is the first reported case of the successful treatment of Pasteurella multocida meningitis with aztreonam in a patient with multiple antibiotic allergies.

Successful treatment of Pasteurella multocida meningitis with aztreonam

This is the first reported case of the successful treatment of Pasteurella multocida meningitis with aztreonam in a patient with multiple antibiotic allergies.

Microbiology, safety, and pharmacokinetics of aztreonam lysinate for inhalation in patients with cystic fibrosis

BACKGROUND

Aztreonam lysinate for inhalation (AI) is a novel monobactam formulation being investigated for pulmonary Pseudomonas aeruginosa infections in patients with cystic fibrosis (CF).

METHODS

Pre-clinical studies investigated the pre- and post-nebulization activity of AI and its activity in the presence of CF sputum. A double-blind, placebo-controlled, dose-escalation trial determined pharmacokinetics and tolerability of AI in subjects with CF. Single daily escalating doses of AI 75, 150, or 225 mg, or placebo were self-administered using an eFlow Electronic Nebulizer. Sputum samples were collected up to 4 hr and blood samples up to 8 hr post-dose.

RESULTS

AI activity against multiple CF isolates was retained after nebulization via eFlow, and activity was not inhibited by CF sputum. All 12 adult subjects and 11/12 adolescents tolerated all AI doses. One patient had an asymptomatic FEV1 decrease > 20% with the 150 mg dose. Median aztreonam sputum concentrations in adults 10 min after AI 75, 150, and 225 mg were 383, 879, and 985 microg/g, respectively. Median sputum concentrations in adolescents 10 min after AI 75, 150, and 225 mg were 324, 387, and 260 microg/g, respectively. Systemic exposure to AI was low. Plasma pharmacokinetics in adults receiving AI 75 mg were Cmax = 419 ng/g, Tmax = 0.99 hr, t1/2 = 2.1 hr. Aztreonam concentrations in sputum were at or above the MIC50 for at least 4 hr post-dose.

CONCLUSION

These data support the continued development of AI for treatment of pulmonary infections in patients with CF.

Systemic antibiotic agents

Understanding the breadth of systemic antimicrobial agents available for use by the dermatologist and their associated side-effect profiles and drug interactions allows the clinician to offer patients optimal care in the management of cutaneous infectious disease.

Antimicrobial therapy in the elderly

This article focuses on the special characteristics of infection in the elderly and provides an update of the principles of antibiotic selection, use of specific antibiotics, and empiric use of antimicrobials in the treatment of infectious diseases in this particularly vulnerable group. Antituberculous, antifungal, and antiviral agents are mentioned briefly; detailed information regarding these classes of agents in reference to aging can be found in standard reviews of antimicrobial therapy in the elderly.

Effects of aztreonam on natural immunity in mice

The influence of the dose and the duration of treatment with aztreonam, a monocyclic beta-lactam antibiotic, on the natural immune response of mice has been investigated. The results show the effects induced by the antibiotic on several immune parameters were affected by the duration of treatment. Thus, treatment with 28 mg/kg per day of aztreonam over 14 days increased every immune parameter tested, while treatment with 57 mg/kg per day of aztreonam for 7 days only enhanced the natural killer (NK) activity of splenocytes. Since aztreonam does not apparently impair the innate immune response, it might be a suitable therapy for the treatment of patients who are immunosuppressed.

Antimicrobial agents for the dermatologist. I. Beta-lactam antibiotics and related compounds

We review the newer antimicrobial agents that are being employed by dermatologists with increased frequency as well as some of the more commonly used older agents. Particular emphasis is based on selection factors such as causative pathogens and their resistance profiles, routes of administration, toxicity, drug interactions, and dosing requirements. Emphasis in this review is on the newer classes of antimicrobials such as third- and fourth-generation cephalosporins; beta-lactam, beta-lactamase inhibitor combination agents; monobactams; carbapenems; macrolides; and fluoroquinolones. Dermatologic indications and treatment alternatives are highlighted; this will expand the practicing clinician's therapeutic armamentarium and enable him/her to make rational decisions concerning treatment approaches to infectious disease problems encountered in daily practice.

Beta-lactam antibiotics: is continuous infusion the preferred method of administration?

OBJECTIVE

To examine the pharmacodynamic properties of the beta-lactam class of antibiotics and the rationale for their continuous infusion (CI), and to explore reasons that this mode of administration has not replaced intermittent infusion as the standard of practice.

DATA SOURCES

A Medline search of the English-language literature evaluating CI administration of beta-lactam antibiotics was conducted. Bibliographic searches of these articles also were performed.

STUDY SELECTION

Because there were few human trials, all available trials were considered for review. A cross section of clinical trials, animal studies, and in vitro studies examining the impact of the route of antibiotic administration was selected for each pharmacodynamic variable addressed.

DATA SYNTHESIS

The support for CI as the preferred method of beta-lactam administration comes primarily from in vitro and animal data. Most beta-lactam antibiotics do not demonstrate concentration-dependent killing and have an appreciable postantibiotic effect only against gram-positive cocci. Their efficacy appears to be optimized by maintaining suprainhibitory concentrations throughout the dosing interval. Therefore, CI of beta-lactams could potentially enhance the efficacy of treatment or allow less drug to be used on a daily basis. This has yet to be demonstrated convincingly in human clinical trials. Comparative trials need to continue to explore the impact of the method of administration on patient outcomes such as duration and cost of therapy, as well as morbidity and mortality.

CONCLUSIONS

Results of many animal and in vitro studies suggest that CI may be the optimal method of beta-lactam administration. Clinical trials need to further document the impact of the method of beta-lactam administration on the incidence of adverse effects, emergence of bacterial resistance, and patient outcome. Pharmacodynamic studies defining target beta-lactam concentrations, the practicality of CI in patients requiring multiple intravenous fluids and medications, and the pertinence of this issue when beta-lactam antibiotics are used as sole agents or in combination with other antimicrobials require further exploration.