Ceftazidime is a potential drug to inhibit cell proliferation by increasing cellular p27

The development of new therapeutic uses for existing drugs is important for the treatment of some diseases. Cephalosporin antibiotics stand as the most extensively utilized antibiotics in clinical practice, effectively combating bacterial infections. Here, we found that the antimicrobial drug ceftazidime strongly upregulates p27 protein levels by inhibiting p27 ubiquitination. The p27 protein is a classic negative regulator of the cell cycle. Next, we demonstrated that ceftazidime can impede the cell cycle from G1 to S phase, thus inhibiting cell proliferation. Furthermore, we found that ceftazidime promotes p27 expression and inhibits cell proliferation by reducing Skp2, which is a substrate recognition component of the Skp2-Cullin-F-box (SCF) ubiquitin ligase. Moreover, ceftazidime downregulates transcriptional expression of Skp2. Importantly, we demonstrated that ceftazidime inhibited the proliferation of tumor cells in vivo. These findings reveal ceftazidime-mediated inhibition of cell proliferation through the Skp2-p27 axis, and could provide a potential strategy for anti-tumor therapy.

Extended Spectrum β-Lactamase-Producing Enterobacterales of Shrimp and Salmon Available for Purchase by Consumers in Canada-A Risk Profile Using the Codex Framework

The extended-spectrum β-lactamase (ESBL)-producing Enterobacterales (ESBL-EB) encompass several important human pathogens and are found on the World Health Organization (WHO) priority pathogens list of antibiotic-resistant bacteria. They are a group of organisms which demonstrate resistance to third-generation cephalosporins (3GC) and their presence has been documented worldwide, including in aquaculture and the aquatic environment. This risk profile was developed following the Codex Guidelines for Risk Analysis of Foodborne Antimicrobial Resistance with the objectives of describing the current state of knowledge of ESBL-EB in relation to retail shrimp and salmon available to consumers in Canada, the primary aquacultured species consumed in Canada. The risk profile found that Enterobacterales and ESBL-EB have been found in multiple aquatic environments, as well as multiple host species and production levels. Although the information available did not permit the conclusion as to whether there is a human health risk related to ESBLs in Enterobacterales in salmon and shrimp available for consumption by Canadians, ESBL-EB in imported seafood available at the retail level in Canada have been found. Surveillance activities to detect ESBL-EB in seafood are needed; salmon and shrimp could be used in initial surveillance activities, representing domestic and imported products.

Synergistic Effect and Time-Kill Evaluation of Eugenol Combined with Cefotaxime Against Staphylococcus aureus

Eugenol, a clove-derived aromatic compound has shown antibacterial activity against many species, including Staphylococcus aureus. Epidemiology studies from the past two decades reported an increased number of healthcare-associated and skin tissue infections due to S. aureus antimicrobial resistance (AMR) including several cases of resistance to β-lactam antibiotics, such as cefotaxime. We aimed to investigate whether eugenol can cause lethality of S. aureus including the strain resistant to methicillin and the wild strain isolated from a hospital patient. Moreover, we asked whether eugenol could enhance the therapeutic effect of cefotaxime, one of the most prescribed 3rd generation cephalosporin β-lactam antibiotics, of which S. aureus resistance to this antibiotic has emerged. The minimum inhibitory concentration (MIC) of each substance was determined using the standard broth microdilution test following the combination experiment performed using checkerboard dilution. The type of interactions, including synergistic and additivity, was determined using isobologram analysis, and the dose reduction index (DRI) was calculated. The time-kill kinetic assay was performed to evaluate the dynamic bactericidal activity of eugenol alone and in combination with cefotaxime. We showed that eugenol alone is bactericidal against S. aureus ATCC 33591 and the clinical isolate. Eugenol combined with cefotaxime resulted synergistic effect against S. aureus ATCC 33591, ATCC 29213, and ATCC 25923. Eugenol may be capable to improve the therapeutic effect of cefotaxime against methicillin-resistant S. aureus (MRSA).

A Case-Report of Drug-Induced Mixed Liver Injury Resulting From Cefepime Exposure

A 99-year-old African-American male presented to the hospital with severe sepsis secondary to a urinary tract infection. Upon initial presentation he was tachycardic, hypotensive and had leukocytosis. While he had signs of acute kidney injury, no signs of acute liver injury were present with his alanine transferase (ALT) and amino transferase (AST) levels measuring at 22 and 44 U/L, respectively. During the treatment course the patient began to show signs of clinical improvement. Despite this, his ALT and AST began to increase on day 2 of treatment and reached their peak of 210 and 239 U/L on day 4. Cefepime-induced liver injury was suspected and cefepime was discontinued. Upon cefepime discontinuation, liver enzymes downtrended and gradually returned to normal. No other likely medication causes of liver injury could be identified and alternative medical causes were ruled out. The lack of an alternative cause and the temporal relationship of cefepime use to hepatic dysfunction support the diagnosis of cefepime-induced liver injury. The patient's Roussel Uclaf Causality Assessment Methods score was 7, indicating this was a possible case of cefepime-induced liver injury, and the Naranjo Nomogram score was 5 indicating this was a probable case of cefepime-induced liver injury. While cefepime-induced liver injury is rare, clinicians should be cognizant of the potential for this adverse effect if liver enzyme elevation is detected during cefepime therapy and other common causes have been ruled out.

Cephalosporins as key lead generation beta-lactam antibiotics

Abstract

Antibiotics are antibacterial compounds that interfere with bacterial growth, without harming the infected eukaryotic host. Among the clinical agents, beta-lactams play a major role in treating infected humans and animals. However, the ever-increasing antibiotic resistance crisis is forcing the pharmaceutical industry to search for new antibacterial drugs to combat a range of current and potential multi-resistant bacterial pathogens. In this review, we provide an overview of the development, innovation, and current status of therapeutic applications for beta-lactams with a focus on semi-synthetic cephalosporins. Cephalosporin C (CPC), which is a natural secondary metabolite from the filamentous fungus Acremonium chrysogenum, plays a major and demanding role in both producing modern antibiotics and developing new ones. CPC serves as a core compound for producing semi-synthetic cephalosporins that can control infections with different resistance mechanisms. We therefore summarize our latest knowledge about the CPC biosynthetic pathway and its regulation in the fungal host. Finally, we describe how CPC serves as a key lead generation source for the in vitro and better, in vivo synthesis of 7-aminocephalosporanic acid (7-ACA), the major core compound for the pharmaceutical synthesis of current and future semi-synthetic cephalosporins.

Key points

•Latest literature on cephalosporin generations

•Biotechnical production of cephalosporins

•In vivo production of 7-ACA

A Straightforward Approach to Synthesize 7-Aminocephalosporanic Acid In Vivo in the Cephalosporin C Producer Acremonium chrysogenum

The pharmaceutical industry has developed various highly effective semi-synthetic cephalosporins, which are generated by modifying the side chains of the core molecule 7-aminocephalosporanic acid (7-ACA). In industrial productions, the 7-ACA nucleus is obtained in vitro from cephalosporin C (CPC) by chemical or enzymatic processes, which are waste intensive and associated with high production costs. Here, we used a transgenic in vivo approach to express bacterial genes for cephalosporin C acylase (CCA) in the CPC producer Acremonium chrysogenum. Western blot and mass spectrometry analyses verified that the heterologous enzymes are processed into α- and β-subunits in the fungal cell. Extensive HPLC analysis detected substrates and products of CCAs in both fungal mycelia and culture supernatants, with the highest amount of 7-ACA found in the latter. Using different incubation times, temperatures, and pH values, we explored the optimal conditions for the active bacterial acylase to convert CPC into 7-ACA in the culture supernatant. We calculated that the best transgenic fungal strains exhibit a one-step conversion rate of the bacterial acylase of 30%. Our findings can be considered a remarkable contribution to supporting future pharmaceutical manufacturing processes with reduced production costs.

Discovery and Development of Antibacterial Agents: Fortuitous and Designed

Today, antibacterial drug resistance has turned into a significant public health issue. Repeated intake, suboptimal and/or unnecessary use of antibiotics, and, additionally, the transfer of resistance genes are the critical elements that make microorganisms resistant to conventional antibiotics. A substantial number of antibacterials that were successfully utilized earlier for prophylaxis and therapeutic purposes have been rendered inadequate due to this phenomenon. Therefore, the exploration of new molecules has become a continuous endeavour. Many such molecules are at various stages of investigation. A surprisingly high number of new molecules are currently in the stage of phase 3 clinical trials. A few new agents have been commercialized in the last decade. These include solithromycin, plazomicin, lefamulin, omadacycline, eravacycline, delafloxacin, zabofloxacin, finafloxacin, nemonoxacin, gepotidacin, zoliflodacin, cefiderocol, BAL30072, avycaz, zerbaxa, vabomere, relebactam, tedizolid, cadazolid, sutezolid, triclosan and afabiacin. This article aims to review the investigational and recently approved antibacterials with a focus on their structure, mechanisms of action/resistance, and spectrum of activity. Delving deep, their success or otherwise in various phases of clinical trials is also discussed while attributing the same to various causal factors.

Design, Synthesis, and Biological Evaluation of Light-Activated Antibiotics

The spatial and temporal control of bioactivity of small molecules by light (photopharmacology) constitutes a promising approach for study of biological processes and ultimately for the treatment of diseases. In this study, we investigated two different "caged" antibiotic classes that can undergo remote activation with UV-light at λ = 365 nm, via the conjugation of deactivating and photocleavable units through a short synthetic sequence. The two widely used antibiotics vancomycin and cephalosporin were thus enhanced in their performance by rendering them photoresponsive and thereby suppressing undesired off-site activity. The antimicrobial activity against Bacillus subtilis ATCC 6633, Staphylococcus aureus ATCC 29213, S. aureus ATCC 43300 (MRSA), Escherichia coli ATCC 25922, and Pseudomonas aeruginosa ATCC 27853 could be spatiotemporally controlled with light. Both molecular series displayed a good activity window. The vancomycin derivative displayed excellent values against Gram-positive strains after uncaging, and the next-generation caged cephalosporin derivative achieved good and broad activity against both Gram-positive and Gram-negative strains after photorelease.

Microbial Resistance Movements: An Overview of Global Public Health Threats Posed by Antimicrobial Resistance, and How Best to Counter

Antibiotics changed medical practice by significantly decreasing the morbidity and mortality associated with bacterial infection. However, infectious diseases remain the leading cause of death in the world. There is global concern about the rise in antimicrobial resistance (AMR), which affects both developed and developing countries. AMR is a public health challenge with extensive health, economic, and societal implications. This paper sets AMR in context, starting with the history of antibiotics, including the discovery of penicillin and the golden era of antibiotics, before exploring the problems and challenges we now face due to AMR. Among the factors discussed is the low level of development of new antimicrobials and the irrational prescribing of antibiotics in developed and developing countries. A fundamental problem is the knowledge, attitude, and practice (KAP) regarding antibiotics among medical practitioners, and we explore this aspect in some depth, including a discussion on the KAP among medical students. We conclude with suggestions on how to address this public health threat, including recommendations on training medical students about antibiotics, and strategies to overcome the problems of irrational antibiotic prescribing and AMR.

Cefpirome Treatment Results in Limited Selection of Stable Derepressed Enterobacter cloacae Mutants in the Intestinal Flora of Rats Treated for an Experimental Klebsiella pneumoniae Pulmonary Infection

Background: Fourth-generation cephalosporins have been developed to improve their potency, that is, low minimal inhibitory concentrations (MICs) and to prevent resistance selection of derepressed AmpC-producing mutants in comparison to third-generation cephalosporins as ceftazidime. Objectives: We investigated the role of the administered cefpirome dose on the efficacy of treatment of a Klebsiella pneumoniae lung infection as well as in the selection of resistant Enterobacter cloacae isolates in the intestines of rats treated for a K. pneumoniae lung infection. Materials and Methods: Rats with K. pneumoniae lung infection received therapy with cefpirome doses of 0.4 to 50 mg/kg/day b.i.d. for 18 days. Resistance selection in intestinal E. cloacae was monitored during 43 days. Mutants were checked for β-lactamase activity, mutations in their structural ampC gene, ampD gene, and omp39-40 gene. Results: A 45% and 100% rat survival rate was obtained by administration of 3.1 and 12.5 mg/kg b.i.d. of cefpirome. A significant correlation was demonstrated in the reduction of the susceptible E. cloacae isolates with %fT>MIC at days 7, 14, 22, and 29. Cefpirome E. cloacae mutants, with increased cefpirome MICs, were obtained in only four rats. Conclusions: The treatment with cefpirome resulted in less selection of derepressed mutants in comparison to ceftazidime as shown by their low number per gram of feces and in a limited number of animals.

Preserving the Dwindling β-lactams-Based Empiric Therapy Options for Gram-Negative Infections in Challenging Resistance Scenario: Lessons Learned and Way Forward

Appropriate empiric therapy reduces mortality and morbidity associated with serious Gram-negative infections. β-lactams (BLs) owing to their safety, efficacy, and coverage spectrum are the most preferred agents for empiric use. Inappropriate use of older penicillins and cephalosporins led to selection and spread of resistant clones. As a result, these valuable agents have lost their reliability compelling clinicians to often use erstwhile last-line therapies such as carbapenems. Excessive carbapenems use imposed collateral damage by selecting difficult-to-treat carbapenem-resistant organisms. Lack of empiric therapeutic options amenable for use in infections caused by contemporary pathogens was realized by the pharmaceutical industry leading to intensive efforts in discovering novel antibiotics. These efforts led to the approval of newer β-lactams and β-lactamase inhibitor (BL-BLI) combination. This review elaborates the past trends in empirical use of BLs and ensuing patterns of resistance emergence in Gram-negatives. Furthermore, a critical appraisal of newer BL-BLIs has been presented to identify the appropriate clinical situations for their use to ensure clinical efficacy coupled with minimal resistance selection. These learning have been derived from past trends of clinical usage of older empiric therapies so that the therapeutic utility of newer agents is preserved for long in light of dwindling global antibiotics pipeline.

Solid nanoparticles for oral antimicrobial drug delivery: a review

Most microbial infectious diseases can be treated successfully with the remarkable array of antimicrobials current available; however, antimicrobial resistance, adverse effects, and the high cost of antimicrobials are crucial health challenges worldwide. One of the common efforts in addressing this issue lies in improving the existing antibacterial delivery systems. Solid nanoparticles (SNPs) have been widely used as promising strategies to overcome these challenges. In addition, oral delivery is the most common method of drug administration with high levels of patient acceptance. Formulation into NPs can improve drug stability in the harsh gastrointestinal (GI) tract environment, providing opportunities for targeting specific sites in the GI tract, increasing drug solubility and bioavailability, and providing sustained release in the GI tract. Here, we discuss SNPs for the oral delivery of antimicrobials, including solid lipid NPs (SLNs), polymeric NPs (PNs), mesoporous silica NPs (MSNs) and hybrid NPs (HNs). We also discussed about the role of nanotechnology in IV to oral antimicrobial therapy development as well as challenges, clinical transformation, and limitations of SNPs for oral antimicrobial drug delivery.

Seventy-Five Years of Research on Protein Binding

This review summarizes evidence that the impact of protein binding of the activity of antibiotics is multifaceted and more complex than indicated by the numerical value of protein binding alone. A plethora of studies has proven that protein binding of antibiotics matters, as the free fraction only is antibacterially active and governs pharmacokinetics. Several studies have indicated that independent from protein binding of immunoglobulin G, albumin, α1-acid-glycoprotein, and pulmonary surfactant acted synergistically with antibacterial agents, thus suggesting that some intrinsic properties of serum proteins may have mediated serum-antibiotic synergisms. It has been demonstrated that IgG and albumin permeabilized Gram-negative and Gram-positive bacteria and facilitated the uptake of poorly penetrating antibiotics. Alpha-1-acid-glycoprotein and pulmonary surfactant also exerted a permeabilizing activity, but proof that this property results in a sensitizing effect is missing. The permeabilizing effect of serum proteins may explain why serum-antibiotic synergisms do not represent a general phenomenon but are limited to specific drug-bug associations only. Although evidence has been generated to support the hypothesis that native serum proteins interact synergistically with antibiotics, systematic and well-controlled studies have to be performed to substantiate this phenomenon. The interactions between serum proteins and bacterial surfaces are driven by physicochemical forces. However, preparative techniques, storage conditions, and incubation methods have a significant impact on the intrinsic activities of these serum proteins affecting serum-antibiotic synergisms, so these techniques have to be standardized; otherwise, contradictory data or even artifacts will be generated.

A randomized open label study of 'imipenem vs. cefepime' in spontaneous bacterial peritonitis

BACKGROUND & AIMS

Spontaneous bacterial peritonitis (SBP), in the presence of bacterial resistance or failure of third generation cephalosporins (3rd GC) has poor outcome. Empirical antibiotic(s) options are limited in these scenarios.

METHODS

Consecutive cirrhotics with SBP because of hospital acquired SBP (>48 h of admission), microbial resistance or non-response (no resolution of SBP at 48 h) were randomized to Cefepime (n = 88) or Imipenem (n = 87) plus standard medical therapy. We assessed for 'response at 48 h' (reduction in ascitic fluid absolute neutrophil count (ANC) by >25% at 48 h), resolution of SBP (<250 cu/mm ANC at day 5) and their clinical outcome.

RESULTS

Of 957 paracentesis in 1200 hospitalized cirrhotics, 253 (26.4%) had SBP and 175 (69.6%) were randomized. Baseline parameters were comparable in two groups. Response at 48 h (58.6% vs. 51.7%; P = 0.4) and resolution of SBP in those with response at 48 h were comparable with no difference in mortality at week 2, month 1 and 3. Patients with 'No response at 48 h' had higher mortality compared with responders (73.8% vs. 25%; P < 0.001). Resolution of SBP was associated with 'response at 48 h' and septic shock, latter being main pre-terminal event. AKI at enrolment [Hazard ratio (HR), 2.6], pneumonia [HR, 2.9], septic shock [HR, 2.2] and response at 48 h [HR, 4.6] predicted poor outcome.

CONCLUSIONS

In hospitalized cirrhotics with SBP and risk factors for treatment failure, cefepime showed comparable efficacy and survival to imipenem. Non-response to therapy at 48 h is a reliable predictor of treatment failure and mortality. Antibiotic combinations and novel options are needed for these patients.

Comparison of the influence on renal function between cefepime and cefpirome

Although known for their broad spectrum and curative efficacy on drug-resistant pathogens and as nephrotoxicity-free, impairments were observed on renal function during clinical treatment of the two most commonly used fourth-generation cephalosporins: Cefpirome and cefepime. The present study aimed to further explore the exact influences of them on renal function. In vitro, the cell viability of renal cells cultured in drug-combined medium was tested for six dilutions. In vivo, a clinical cohort study was carried out to detect the influence of cefpirome and cefepime on the serum creatinine (SCr) level of patients. Cefpirome had an inhibition rate with half maximal inhibitory concentration (IC₅₀) of 143.5 µmol/l on renal mesangial cells, which was greater compared to the IC₅₀ of 7.702 µmol/l for cefepime. The clinical cohort study data revealed that cefpirome treatment could lead to a greater increase of the average SCr level compared to cefepime on days 3 and 7 during therapy, and in addition, a greater incidence of SCr >445 µmol/l, an indicator of clinical renal failure. Furthermore, patients with an average age >65 years were observed as more susceptible to an SCr rise caused by either cefpirome or cefepime, with a larger augment in the average SCr, as well as a higher incidence of SCr >445 µmol/l compared to patients aged <65 years. In conclusion, cefpirome may have more potential to cause renal impairment compared to cefepime, therefore, more caution and comprehensive analysis of patient conditions is required during the clinical choice of fourth-generation cephalosporins.

The evolving role of chemical synthesis in antibacterial drug discovery

The discovery and implementation of antibiotics in the early twentieth century transformed human health and wellbeing. Chemical synthesis enabled the development of the first antibacterial substances, organoarsenicals and sulfa drugs, but these were soon outshone by a host of more powerful and vastly more complex antibiotics from nature: penicillin, streptomycin, tetracycline, and erythromycin, among others. These primary defences are now significantly less effective as an unavoidable consequence of rapid evolution of resistance within pathogenic bacteria, made worse by widespread misuse of antibiotics. For decades medicinal chemists replenished the arsenal of antibiotics by semisynthetic and to a lesser degree fully synthetic routes, but economic factors have led to a subsidence of this effort, which places society on the precipice of a disaster. We believe that the strategic application of modern chemical synthesis to antibacterial drug discovery must play a critical role if a crisis of global proportions is to be averted.

Antibiotics for emerging pathogens

Antibiotic-resistant strains of pathogenic bacteria are increasingly prevalent in hospitals and the community. New antibiotics are needed to combat these bacterial pathogens, but progress in developing them has been slow. Historically, most antibiotics have come from a small set of molecular scaffolds whose functional lifetimes have been extended by generations of synthetic tailoring. The emergence of multidrug resistance among the latest generation of pathogens suggests that the discovery of new scaffolds should be a priority. Promising approaches to scaffold discovery are emerging; they include mining underexplored microbial niches for natural products, designing screens that avoid rediscovering old scaffolds, and repurposing libraries of synthetic molecules for use as antibiotics.

Activity of cefepime, cefotaxime, ceftazidime, and aztreonam against extended-spectrum-producing isolates of Klebsiella pneumoniae and Escherichia coli from Chilean hospitals

Resistance of Gram-negative bacilli to third-generation cephalosporins has been increasing due to the production of extended-spectrum beta-lactamases. In this work, the activities of cefepime, cefotaxime, ceftazidime, and aztreonam, alone and in association with clavulanic acid, against isolates of Klebsiella pneumoniae and Escherichia coli are compared. These isolates produce extended-spectrum beta-lactamases as shown by the synergy tests and by the decrease in the MICs of cephalosporins in the presence of clavulanic acid. Cefepime was the most active compound against these microorganisms. In addition, the microorganisms exhibited lower frequencies of resistance to this cephalosporin.

An extended-spectrum AmpC-type beta-lactamase obtained by in vitro antibiotic selection

A predictive approach was assayed to evaluate the possibility of mutant Amp-C beta-lactamase emergence with increased substrate spectrum (including new C-3' quaternary ammonium cephems). The ampC gene encoding the AmpC beta-lactamase from Enterobacter cloacae was cloned and expressed in an AmpC-defective strain of E. coli. After the AmpC containing strain was challenged with cefpirome, an ampC variant encoding an enzyme with increased resistance to cefpirome and cefepime was selected. In addition, this variant conferred increased resistance to penicillins and third generation cephalosporins. The complete nucleotide sequence of the gene was determined. The deduced peptide sequence showed a single change with respect to the wild-type gene: valine to glutamic acid at position 318 of the native protein (298 of the mature enzyme). The potential emergence and spread of this type of AmpC variants among pathogens should be considered.