In Vitro Activity of a Novel Siderophore-Cephalosporin LCB10-0200 (GT-1), and LCB10-0200/Avibactam, against Carbapenem-Resistant Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa Strains at a Tertiary Hospital in Korea

Difficult-to-treat (DTR) Pseudomonas aeruginosa harboring Verona-Integron metallo-β-lactamase (blaVIM): infection management and molecular analysis

Pseudomonas aeruginosa harboring Verona Integron-encoded metallo-β-lactamase enzymes (VIM-CRPA) have been associated with infection outbreaks in several parts of the world. In the US, however, VIM-CRPA remain rare. Starting in December 2018, we identified a cluster of cases in our institution. Herein, we present our epidemiological investigation and strategies to control/manage these challenging infections. This study was conducted in a large academic healthcare system in Miami, FL, between December 2018 and January 2022. Patients were prospectively identified via rapid molecular diagnostics when cultures revealed carbapenem-resistant P. aeruginosa. Alerts were received in real time by the antimicrobial stewardship program and infection prevention teams. Upon alert recognition, a series of interventions were performed as a coordinated effort. A retrospective chart review was conducted to collect patient demographics, antimicrobial therapy, and clinical outcomes. Thirty-nine VIM-CRPA isolates led to infection in 21 patients. The majority were male (76.2%); the median age was 52 years. The majority were mechanically ventilated (n = 15/21; 71.4%); 47.6% (n = 10/21) received renal replacement therapy at the time of index culture. Respiratory (n = 20/39; 51.3%) or bloodstream (n = 13/39; 33.3%) were the most common sources. Most infections (n = 23/37; 62.2%) were treated with an aztreonam-avibactam regimen. Six patients (28.6%) expired within 30 days of index VIM-CRPA infection. Fourteen isolates were selected for whole genome sequencing. Most of them belonged to ST111 (12/14), and they all carried blaVIM-2 chromosomally. This report describes the clinical experience treating serious VIM-CRPA infections with either aztreonam-ceftazidime/avibactam or cefiderocol in combination with other agents. The importance of implementing infection prevention strategies to curb VIM-CRPA outbreaks is also demonstrated.

Conjugation to Native and Nonnative Triscatecholate Siderophores Enhances Delivery and Antibacterial Activity of a β-Lactam to Gram-Negative Bacterial Pathogens

Developing new antibiotics and delivery strategies is of critical importance for treating infections caused by Gram-negative bacterial pathogens. Hijacking bacterial iron uptake machinery, such as that of the siderophore enterobactin (Ent), represents one promising approach toward these goals. Here, we report a novel Ent-inspired siderophore-antibiotic conjugate (SAC) employing an alternative siderophore moiety as the delivery vector and demonstrate the potency of our SACs harboring the β-lactam antibiotic ampicillin (Amp) against multiple pathogenic Gram-negative bacterial strains. We establish the ability of N,N',N''-(nitrilotris(ethane-2,1-diyl))tris(2,3-dihydroxybenzamide) (TRENCAM, hereafter TC), a synthetic mimic of Ent, to facilitate drug delivery across the outer membrane (OM) of Gram-negative pathogens. Conjugation of Amp to a new monofunctionalized TC scaffold affords TC-Amp, which displays markedly enhanced antibacterial activity against the gastrointestinal pathogen Salmonella enterica serovar Typhimurium (STm) compared with unmodified Amp. Bacterial uptake, antibiotic susceptibility, and microscopy studies with STm show that the TC moiety facilitates TC-Amp uptake by the OM receptors FepA and IroN and that the Amp warhead inhibits penicillin-binding proteins. Moreover, TC-Amp achieves targeted activity, selectively killing STm in the presence of a commensal lactobacillus. Remarkably, we uncover that TC-Amp and its Ent-based predecessor Ent-Amp achieve enhanced antibacterial activity against diverse Gram-negative ESKAPE pathogens that express Ent uptake machinery, including strains that possess intrinsic β-lactam resistance. TC-Amp and Ent-Amp exhibit potency comparable to that of the FDA-approved SAC cefiderocol against Gram-negative pathogens. These results demonstrate the effective application of native and appropriately designed nonnative siderophores as vectors for drug delivery across the OM of multiple Gram-negative bacterial pathogens.

Novel drug candidates against antibiotic-resistant microorganisms: A review

Antibiotic resistance is fast spreading globally, leading to treatment failures and adverse clinical outcomes. This review focuses on the resistance mechanisms of the top five threatening pathogens identified by the World Health Organization's global priority pathogens list: carbapenem-resistant Acinetobacter baumannii, carbapenem-resistant Pseudomonas aeruginosa, carbapenem-resistant, extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae, vancomycin-resistant Enterococcus faecium and methicillin, vancomycin-resistant Staphylococcus aureus. Several novel drug candidates have shown promising results from in vitro and in vivo studies, as well as clinical trials. The novel drugs against carbapenem-resistant bacteria include LCB10-0200, apramycin, and eravacycline, while for Enterobacteriaceae, the drug candidates are LysSAP-26, DDS-04, SPR-206, nitroxoline, cefiderocol, and plazomicin. TNP-209, KBP-7072, and CRS3123 are agents against E. faecium, while Debio 1450, gepotidacin, delafloxacin, and dalbavancin are drugs against antibiotic-resistant S. aureus. In addition to these identified drug candidates, continued in vitro and in vivo studies are required to investigate small molecules with potential antibacterial effects screened by computational receptor docking. As drug discovery progresses, preclinical and clinical studies should also be extensively conducted on the currently available therapeutic agents to unravel their potential antibacterial effect and spectrum of activity, as well as safety and efficacy profiles.

Antibiotics in the clinical pipeline as of December 2022

The need for new antibacterial drugs to treat the increasing global prevalence of drug-resistant bacterial infections has clearly attracted global attention, with a range of existing and upcoming funding, policy, and legislative initiatives designed to revive antibacterial R&D. It is essential to assess whether these programs are having any real-world impact and this review continues our systematic analyses that began in 2011. Direct-acting antibacterials (47), non-traditional small molecule antibacterials (5), and β-lactam/β-lactamase inhibitor combinations (10) under clinical development as of December 2022 are described, as are the three antibacterial drugs launched since 2020. Encouragingly, the increased number of early-stage clinical candidates observed in the 2019 review increased in 2022, although the number of first-time drug approvals from 2020 to 2022 was disappointingly low. It will be critical to monitor how many Phase-I and -II candidates move into Phase-III and beyond in the next few years. There was also an enhanced presence of novel antibacterial pharmacophores in early-stage trials, and at least 18 of the 26 phase-I candidates were targeted to treat Gram-negative bacteria infections. Despite the promising early-stage antibacterial pipeline, it is essential to maintain funding for antibacterial R&D and to ensure that plans to address late-stage pipeline issues succeed.

Antibacterial Activity of LCB10-0200 against Klebsiella pneumoniae

Klebsiella pneumoniae is one of the important clinical organisms that causes various infectious diseases, including urinary tract infections, necrotizing pneumonia, and surgical wound infections. The increase in the incidence of multidrug-resistance K. pneumoniae is a major problem in public healthcare. Therefore, a novel antibacterial agent is needed to treat this pathogen. Here, we studied the in vitro and in vivo activities of a novel antibiotic LCB10-0200, a siderophore-conjugated cephalosporin, against clinical isolates of K. pneumoniae. In vitro susceptibility study found that LCB10-0200 showed potent antibacterial activity against K. pneumoniae, including the beta-lactamase producing strains. The in vivo efficacy of LCB10-0200 was examined in three different mouse infection models, including systemic, thigh, and urinary tract infections. LCB10-0200 showed more potent in vivo activity than ceftazidime in the three in vivo models against the drug-susceptible and drug-resistant K. pneumoniae strains. Taken together, these results show that LCB10-0200 is a potential antibacterial agent to treat infection caused by K. pneumoniae.