In vitro activity of plazomicin compared to other clinically relevant aminoglycosides in carbapenem-resistant Enterobacteriaceae

Efficacy and safety of plazomicin in the treatment of Enterobacterales infections: A meta-analysis of randomized controlled trials

Background

In the present study, we aimed to compare the efficacy and safety of plazomicin with comparators for the treatment of Enterobacterales infections.

Methods

Randomized controlled trials (RCTs) assessing plazomicin for Enterobacterales infections were searched on the PubMed, Embase, and Cochrane Library databases. Meta-analyses were used to evaluate the efficacy and safety in RCTs.

Results

A total of 3 RCTs consisting of 761 patients were included in the present analysis. The study population included complex urinary tract infections (cUTIs), bloodstream infections (BSIs), and hospital-acquired pneumonia (HAP). Plazomicin had a clinical remission rate in the modified intention-to-treat (MITT) population that was similar to that of comparators (odds ratio [OR], 1.02; 95% CI, 0.60–1.73; I² = 45%) in the pooled analysis of the 3 studies. The overall microbiologic eradication rate in the microbiological MITT (mMITT) population was similar to that of the comparators group (OR, 1.46; 95% CI, 0.72–2.95; I² = 0%). However, the microbiologic recurrence rate of plazomicin for Enterobacterales was lower than that in the comparators group (OR, 0.38; 95% CI, 0.17–0.86; P = .02; I² = 0%). No significant differences were found between plazomicin and comparators for the risk of any adverse events (OR, 0.78; 95% CI, 0.55–1.11; I² = 0%).

Conclusions

Plazomicin is as good as comparators in terms of efficacy and tolerance in the treatment of Enterobacterales infections. Therefore, plazomicin is a suitable choice for antibiotic treatment in adult patients with cUTIs, BSIs, or HAP.

Antimicrobial Treatment Options for Difficult-to-Treat Resistant Gram-Negative Bacteria Causing Cystitis, Pyelonephritis, and Prostatitis: A Narrative Review

Urinary tract infections, including cystitis, acute pyelonephritis, and prostatitis, are among the most common diagnoses prompting antibiotic prescribing. The rise in antimicrobial resistance over the past decades has led to the increasing challenge of urinary tract infections because of multidrug-resistant and "difficult-to-treat resistance" among Gram-negative bacteria. Recent advances in pharmacotherapy and medical microbiology are modernizing how these urinary tract infections are treated. Advances in pharmacotherapy have included not only the development and approval of novel antibiotics, such as ceftazidime/avibactam, meropenem/vaborbactam, imipenem/relebactam, ceftolozane/tazobactam, cefiderocol, plazomicin, and glycylcyclines, but also the re-examination of the potential role of legacy antibiotics, including older aminoglycosides and tetracyclines. Recent advances in medical microbiology allow phenotypic and molecular mechanism of resistance testing, and thus antibiotic prescribing can be tailored to the mechanism of resistance in the infecting pathogen. Here, we provide a narrative review on the clinical and pre-clinical studies of drugs that can be used for difficult-to-treat resistant Gram-negative bacteria, with a particular focus on data relevant to the urinary tract. We also offer a pragmatic framework for antibiotic selection when encountering urinary tract infections due to difficult-to-treat resistant Gram-negative bacteria based on the organism and its mechanism of resistance.

In Vitro Activity of Plazomicin among Carbapenem-resistant Enterobacteriaceae

Background:  Carbapenem-resistant Enterobacteriaceae (CRE) have been disseminated worldwide and became a global threat. Due to limited therapeutic drugs plazomicin - a new semisynthetic aminoglycoside - have been suggested as an alternative option owing to its stability against aminoglycosides modifying enzymes (AMEs). This study aims to assess the in vitro activity of plazomicin against CRE isolates and to detect different types of carbapenemases among these isolates. Material and Methods: In this study, 102 CRE isolates were collected from different clinical samples at Cairo University hospitals and the presence of carbapenemases was detected by modified carbapenem inhibition method (mCIM) and multiplex PCR tests. Plazomicin susceptibility testing was done using E test. Results: The most frequently detected carbapenemase genes were blaNDM in 75 (73.5%) isolates, followed by blaOXA-48 in 57 (55.9%) and blaKPC in 16 (15.5%) isolates. Plazomicin was active against 32 (31.4%) isolates. Among the isolates carrying blaNDM gene only and those carrying blaOXA-48 gene only, 21% and 41% were sensitive to plazomicin, respectively. Plazomicin showed the highest sensitivity against CRE isolates compared to the other tested antibiotics. Conclusion: Plazomicin might be a good option for treatment of infections caused by CRE. In health care settings where blaNDM gene is prevalent, plazomicin may not be a good therapeutic option for CRE infections.

Multicenter Clinical Evaluation Of ETEST® Plazomicin (PLZ) For Susceptibility Testing Of Enterobacterales

Plazomicin (PLZ), brand name ZEMDRI (Cipla Therapeutics), is a novel aminoglycoside antibiotic approved by the US Food and Drug Administration (FDA) for treatment of complicated urinary tract infections including pyelonephritis. ETEST® is a gradient diffusion method that represents an alternative to the more laborious broth micro-dilution (BMD) method for performing antimicrobial susceptibility testing (AST). A multi-center evaluation of the performance of the new ETEST® PLZ (bioMérieux) was conducted in comparison with BMD following FDA and International Standards Organization (ISO) recommendations using FDA-defined breakpoints. Clinical isolates of Enterobacterales (n=598) were included. Fifty-three isolates were resistant to PLZ according to BMD. Overall, the ETEST® PLZ demonstrated 99.0% Essential Agreement (EA), 92.8% Category Agreement (CA), 1.9% Very Major Errors (VME), 0% Major Errors (ME) and 7.0% minor Errors (mE) with both clinical and challenge isolates of Enterobacterales. The VME was found for a single Serratia marcescens strain. Individual species demonstrated EA rates ≥ 90%. In conclusion, we report that ETEST® PLZ represents an accurate tool for performing PLZ AST of Enterobacterales.

Comparative activity of plazomicin against extended-spectrum cephalosporin-resistant Escherichia coli clinical isolates (2012-2017) in relation to phylogenetic background, sequence type 131 subclones, blaCTX-M genotype, and resistance to comparator agents

Extended-spectrum cephalosporin-resistant Escherichia coli (ESCREC) are a growing threat. Leading ESCREC lineages include sequence type ST131, especially its (blaCTX-M-15-associated) H30Rx subclone and (blaCTX-M-27-associated) C1-M27 subset within the H30R1 subclone. The comparative activity against such strains of alternative antimicrobial agents, including the recently developed aminoglycoside plazomicin, is undefined, so was investigated here. We assessed plazomicin and 11 comparators for activity against 216 well-characterized ESCREC isolates (Minnesota, 2012-2017) and then compared broth microdilution MICs with phylogenetic and clonal background, beta-lactamase genotype (blaCTX-M; group 1 and 9 variants), and co-resistance. Percent susceptible was > 99% for plazomicin, meropenem, imipenem, and tigecycline; 96-98% for amikacin and ertapenem; and ≤ 75% for the remaining comparators. For most comparators, MICs varied significantly in relation to multiple bacterial characteristics, in agent-specific patterns. By contrast, for plazomicin, the only bacterial characteristic significantly associated with MICs was ST131 subclone: plazomicin MICs were lowest among O16 ST131 isolates and highest among ST131-H30R1 C1-M27 subclone isolates. Additionally, plazomicin MICs varied significantly in relation to resistance vs. susceptibility to comparator agents only for amikacin and levofloxacin. For most study agents, antimicrobial activity against ESCREC varied extensively in relation to multiple bacterial characteristics, including clonal background, whereas for plazomicin, it varied only by ST131 subclone (C1-M27 isolates least susceptible, O16 isolates most susceptible). These findings support plazomicin as a reliable alternative for treating ESCREC infections and urge continued attention to the C1-M27 ST131 subclone.

Activity of plazomicin against carbapenem-intermediate or -resistant Escherichia coli isolates from the United States and international sites in relation to clonal background, resistance genes, co-resistance, and region

BACKGROUND

Emerging carbapenem resistance in Escherichia coli, including sequence type 131 (ST131), threatens therapeutic efficacy. Plazomicin (PLZ), a semisynthetic aminoglycoside approved by the FDA in 2018, overcomes the most common aminoglycoside resistance mechanisms and maintains activity against many carbapenem-intermediate or -resistant (CIR) E. coli strains.

OBJECTIVES

To assess plazomicin susceptibility among CIR E. coli in relation to region and multiple bacterial characteristics.

METHODS

We determined broth microdilution MICs for plazomicin and 11 comparators against 343 CIR clinical E. coli isolates, then compared susceptibility results by bacterial characteristics and region. The collection comprised 203 US isolates (2002-17) and 141 isolates from 17 countries in Europe, Latin America, and the Asia-West Pacific region (2003-17). Isolates were characterized for phylogenetic group, resistance-associated sequence types (STs) and subsets thereof, and relevant β-lactamase-encoding genes.

RESULTS

Plazomicin exhibited the highest percentage susceptible (89%) after tigecycline (99%). The percentage susceptible to plazomicin varied significantly by phylogroup (63%, group B1; versus >93%, others) and ST131 subclone (92%, H30Rx; versus 87%-89%, H30R1 and non-H30), but not ST. It also varied by resistance genotype [higher with Klebsiella pneumoniae carbapenemase (KPC), lower with metallo-β-lactamases], global region [highest for Latin America (94%), lowest for Asia-West Pacific (69%)], and US region (80%, South, versus 96%-100%, others). Although reduced susceptibility to comparators often predicted reduced susceptibility to plazomicin, even among comparator-intermediate or -resistant isolates the plazomicin-susceptible fraction was ≥77%, except for amikacin (53%).

CONCLUSIONS

The likely utility of plazomicin against CIR E. coli is high overall, but varies with region and multiple bacterial characteristics.

Present and Future Perspectives on Therapeutic Options for Carbapenemase-Producing Enterobacterales Infections

Carbapenem-resistant Enterobacterales (CRE) are included in the list of the most threatening antibiotic resistance microorganisms, being responsible for often insurmountable therapeutic issues, especially in hospitalized patients and immunocompromised individuals and patients in intensive care units. The enzymatic resistance to carbapenems is encoded by different β-lactamases belonging to A, B or D Ambler class. Besides compromising the activity of last-resort antibiotics, CRE have spread from the clinical to the environmental sectors, in all geographic regions. The purpose of this review is to present present and future perspectives on CRE-associated infections treatment.

Therapeutic Options for Metallo-β-Lactamase-Producing Enterobacterales

The spread of metallo-β-lactamase (MBL)-producing Enterobacterales worldwide without the simultaneous increase in active antibiotics makes these organisms an urgent public health threat. This review summarizes recent advancements in diagnostic and treatment strategies for infections caused by MBL-producing Enterobacterales. Adequate treatment of patients infected with MBL-producing Enterobacterales relies on detection of the β-lactamase in the clinic. There are several molecular platforms that are currently available to identify clinically relevant MBLs as well as other important serine-β-lactamases. Once detected, there are several antibiotics that have historically been used for the treatment of MBL-producing Enterobacterales. Antimicrobials such as aminoglycosides, tetracyclines, fosfomycin, and polymyxins often show promising in vitro activity though clinical data are currently lacking to support their widespread use. Ceftazidime-avibactam combined with aztreonam is promising for treatment of infections caused by MBL-producing Enterobacterales and currently has the most clinical data of any available antibiotic to support its use. While cefiderocol has displayed promising activity against MBL-producing Enterobacterales in vitro and in preliminary clinical studies, further clinical studies will better shed light on its place in treatment. Lastly, there are several promising MBL inhibitors in the pipeline, which may further improve the treatment of MBL-producing Enterobacterales.