Post-β-lactamase-inhibitor effect of tazobactam in combination with ceftolozane on extended-spectrum-β-lactamase-producing strains

In vitro activity of cefiderocol against carbapenemase-producing and meropenem-non-susceptible Gram-negative bacteria collected in the Japan Antimicrobial Resistant Bacterial Surveillance

OBJECTIVES

The treatment options available for infections caused by multidrug-resistant Gram-negative pathogens are often limited. Cefiderocol (CFDC) is a novel siderophore cephalosporin that exhibits activity against these pathogens. Several studies have reported the in vitro activity of CFDC against isolates from Europe, the United States, and China, but the activity against carbapenem-resistant bacteria with IMP-type carbapenemase has not been extensively studied. We, therefore, studied the in vitro activities of CFDC against carbapenem-resistant bacteria with available genomic backgrounds based on whole-genome sequencing (WGS) in Japan, where the IMP-type is the predominant carbapenemase produced by Gram-negative rods.

METHODS

We selected 603 isolates (528 Enterobacterales, 18 Pseudomonas aeruginosa, and 57 Acinetobacter spp.) from a collection of Gram-negative clinical isolates collected during a Japan Antimicrobial Resistance Bacterial Surveillance program and evaluated the antimicrobial activities of CFDC, ceftolozane/tazobactam (CTLZ/TAZ), imipenem-relebactam (IPM/REL), and ceftazidime/avibactam (CAZ/AVI) against carbapenemase-producing Enterobacterales, carbapenemase-non-producing meropenem-non-susceptible Enterobacterales, and carbapenemase-producing nonfermentative bacteria.

RESULTS

Among these, 97.7% of carbapenemase-producing Enterobacterales (99.2% of IMP-type carbapenemase-producing Enterobacterales), 100% of carbapenemase-producing P. aeruginosa, and 91.2% of carbapenemase-producing Acinetobacter spp. were susceptible to CFDC, showing better antimicrobial activity than the other antimicrobial agents evaluated in this study. CFDC was highly effective against class A-, B-, and D β-lactamase-harbouring isolates when compared to the other antimicrobial agents. In addition, the relationship between CFDC resistance and three genetic factors involved in resistance was discussed.

CONCLUSIONS

This is the first large-scale study to systematically demonstrate the efficacy of CFDC against IMP-type carbapenemase-producing strains with known genomic backgrounds.

Ceftolozane-tazobactam and ceftazidime-avibactam activity against β-lactam-resistant Pseudomonas aeruginosa and extended-spectrum β-lactamase-producing Enterobacterales clinical isolates from U.S. medical centres

BACKGROUND

Despite availability of ceftolozane-tazobactam (C/T) and ceftazidime-avibactam (CZA) for several years, the individual spectrum of activity of each agent may not be widely known. We compared the activity of C/T and CZA against convenience samples of 119 extended-spectrum β-lactamase (ESBL)-producing Enterobacterales and 60 β-lactam-resistant Pseudomonas aeruginosa clinical isolates collected from three U.S. institutions.

METHODS

Minimal inhibitory concentrations (MICs) for C/T and CZA were determined by broth microdilution. Molecular identification of nine β-lactamase gene targets was conducted for Enterobacterales and P. aeruginosa isolates with increased MICs to C/T or CZA.

RESULTS

More than 90% of Enterobacterales isolates demonstrated susceptibility to both C/T and CZA, in contrast to the other traditional β-lactam agents tested, which were much less active. The MIC_50/90 values were nearly equivalent between agents. The most common β-lactamase genes identified in Enterobacterales isolates with MIC values ≥2 mg/L were the CTX-M-1 group (85%) and CMY-2-like (23%) β-lactamases. Both agents were active against >80% of β-lactam-resistant P. aeruginosa isolates tested, most of which had oprD mutations identified. One P. aeruginosa isolate was positive for a Klebsiella pneumoniae carbapenemase-type gene but remained meropenem-susceptible. The MIC₅₀ values were four-fold lower in favour of C/T (1 mg/L vs. 4 mg/L) against P. aeruginosa.

CONCLUSIONS

Our data suggest that either agent may be a reasonable choice for centres with a high proportion of ESBL producers; however, C/T may have improved activity against P. aeruginosa and may be preferred in institutions with a higher frequency of resistant pseudomonal isolates.

Treatment of infections caused by multidrug-resistant Gram-negative bacteria: report of the British Society for Antimicrobial Chemotherapy/Healthcare Infection Society/British Infection Association Joint Working Party

The Working Party makes more than 100 tabulated recommendations in antimicrobial prescribing for the treatment of infections caused by multidrug-resistant (MDR) Gram-negative bacteria (GNB) and suggest further research, and algorithms for hospital and community antimicrobial usage in urinary infection. The international definition of MDR is complex, unsatisfactory and hinders the setting and monitoring of improvement programmes. We give a new definition of multiresistance. The background information on the mechanisms, global spread and UK prevalence of antibiotic prescribing and resistance has been systematically reviewed. The treatment options available in hospitals using intravenous antibiotics and in primary care using oral agents have been reviewed, ending with a consideration of antibiotic stewardship and recommendations. The guidance has been derived from current peer-reviewed publications and expert opinion with open consultation. Methods for systematic review were NICE compliant and in accordance with the SIGN 50 Handbook; critical appraisal was applied using AGREE II. Published guidelines were used as part of the evidence base and to support expert consensus. The guidance includes recommendations for stakeholders (including prescribers) and antibiotic-specific recommendations. The clinical efficacy of different agents is critically reviewed. We found there are very few good-quality comparative randomized clinical trials to support treatment regimens, particularly for licensed older agents. Susceptibility testing of MDR GNB causing infection to guide treatment needs critical enhancements. Meropenem- or imipenem-resistant Enterobacteriaceae should have their carbapenem MICs tested urgently, and any carbapenemase class should be identified: mandatory reporting of these isolates from all anatomical sites and specimens would improve risk assessments. Broth microdilution methods should be adopted for colistin susceptibility testing. Antimicrobial stewardship programmes should be instituted in all care settings, based on resistance rates and audit of compliance with guidelines, but should be augmented by improved surveillance of outcome in Gram-negative bacteraemia, and feedback to prescribers. Local and national surveillance of antibiotic use, resistance and outcomes should be supported and antibiotic prescribing guidelines should be informed by these data. The diagnosis and treatment of both presumptive and confirmed cases of infection by GNB should be improved. This guidance, with infection control to arrest increases in MDR, should be used to improve the outcome of infections with such strains. Anticipated users include medical, scientific, nursing, antimicrobial pharmacy and paramedical staff where they can be adapted for local use.

Pharmacokinetics and Pharmacodynamics of β-Lactamase Inhibitors

Novel β-lactamase inhibitors have extended the reach of new and existing β-lactams against multidrug-resistant bacteria expressing β-lactamases. The efficacy of these combination therapeutics relies on a complex two-component pharmacodynamic (PD) system where the β-lactamase inhibitor inactivates the bacterial β-lactamase enzyme and frees the companion β-lactam to act against its penicillin-binding protein target. Despite considerable investigation into the pharmacokinetics (PK) and pharmacodynamics of β-lactams, the pharmacology of their companion β-lactamase inhibitors has only recently been rigorously explored. This review describes the diversity of β-lactamase enzymes, mechanisms of enzyme inhibition, and factors impacting the efficacy of clinically available β-lactamase inhibitors. Relevant PK differences among available inhibitors and the PK/PD properties of these agents are described independently of their companion β-lactams. In the modern era of antibiotic resistance, a comprehensive understanding of the pharmacology, PK, and PD of β-lactamase inhibitors is paramount to maximizing the therapeutic efficacy of existing β-lactam/β-lactamase inhibitor combinations and protecting novel agents in the drug development pipeline.

Imidazole decreases the ampicillin resistance of an Escherichia coli strain isolated from a cow with mastitis by inhibiting the function of autoinducer 2

Extended-spectrum β-lactamase-positive Escherichia coli is an important causative agent of mastitis in dairy cows that results in reduced milk production and quality, and is responsible for severe economic losses in the dairy industry worldwide. The quorum sensing signaling molecule autoinducer 2 (AI-2) is produced by many species of gram-negative and gram-positive bacteria, and might be a universal language for intraspecies and interspecies communication. Our previous work confirmed that exogenous AI-2 increases the antibiotic resistance of extended-spectrum β-lactamase-positive E. coli to the β-lactam group of antibiotics by upregulating the expression of the TEM-type β-lactamase. In addition, this regulation relies on the function of the intracellular AI-2 receptor LsrR. In the present work, we reported that exogenous imidazole, a furan carbocyclic analog of AI-2, decreases the antibiotic resistance of a clinical E. coli strain to β-lactam antibiotics by inhibiting the function of AI-2.

The postantibiotic effect and post-β-lactamase-inhibitor effect of ceftazidime, ceftaroline and aztreonam in combination with avibactam against target Gram-negative bacteria

The magnitudes of the postantibiotic effect (PAE) and post-β-lactamase-inhibitory effect (PLIE) of ceftazidime-avibactam, ceftaroline-avibactam, and aztreonam-avibactam were determined against isolates of Enterobacteriaceae and Pseudomonas aeruginosa that either harboured genes encoding serine and/or metallo-β-lactamases, or did not harbour bla genes. The bla genes included ones that encoded extended spectrum β-lactamases, AmpC and KPC β-lactamases, and one metallo-β-lactamase, NDM-1. No substantial PAE was observed for any combination against any isolate. One substantial PLIE was found: a value of 1·9 h for ceftazidime-avibactam against Klebsiella pneumoniae (blaKPC-2 ). From comparison with results in the literature, we propose that the existence of a substantial PLIE depends on the bacterial isolate and on the specific β-lactamase inhibitor and β-lactam combination.

SIGNIFICANCE AND IMPACT OF THE STUDY

A wave of new β-lactamase inhibitors is entering either therapeutic use or clinical trials. The present work characterizes the postantibiotic effect (PAE) and post-β-lactamase-inhibitory effect (PLIE) of the clinically most advanced of these compounds, avibactam. We show that the existence of a measurable PLIE is strain- (and possibly compound-) dependent, and cannot be relied upon as a standard component of the primary pharmacology of a new β-lactamase inhibitor. This variability was not reported in earlier studies of clavulanic acid or sulbactam.

Ceftolozane/tazobactam and ceftazidime/avibactam: two novel β-lactam/β-lactamase inhibitor combination agents for the treatment of resistant Gram-negative bacterial infections

The rise in resistant Gram-negative bacteria is a major concern and has led to difficulty in treating multidrug-resistant (MDR) infections. Two recently approved combination antibiotics, ceftolozane/tazobactam and ceftazidime/avibactam, may be effective in treating these resistant infections. Ceftolozane is a novel cephalosporin that has been developed in combination with tazobactam, a recognised β-lactamase inhibitor (BLI). Avibactam is a novel BLI combined with ceftazidime, a cephalosporin with an established history. Both of these β-lactam/BLI combination agents have been shown to retain in vitro activity against selected resistant Gram-negative pathogens, including Enterobacteriaceae and Pseudomonas aeruginosa; notably, ceftazidime/avibactam has demonstrated consistent activity against Klebsiella pneumoniae carbapenemase (KPC)-producing organisms. Both agents have been approved for the indications of complicated intra-abdominal infection (with metronidazole) and complicated urinary tract infection, and have ongoing phase 3 trials for the treatment of ventilator-associated and nosocomial pneumonia. This manuscript will review current data available regarding the spectrum of activity and clinical trials that led to the US Food and Drug Administration (FDA) approval of these agents. Both agents appear to be well tolerated and show promise in the treatment of MDR Gram-negative infections.