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ABSTRACT Imipenem-relebactam is a novel β-lactam-β-lactamase inhibitor combination. We evaluated the in vitro activity of imipenem-relebactam and comparators against Enterobacterales clinical isolates recovered in 8 Spanish and 11 Portuguese intensive care units (ICUs) (SUPERIOR, 2016–2017; STEP, 2017–2018). Overall, 747 Enterobacterales isolates (378 Escherichia coli, 252 Klebsiella spp., 64 Enterobacter spp., and 53 other species) were prospectively collected from ICU patients with complicated intraabdominal (cIAI), complicated urinary tract (cUTI), and lower respiratory tract (LRTI) infections. MICs were determined (ISO-broth microdilution), and whole-genome sequencing (WGS) was performed in a subset of isolates displaying susceptible and resistant imipenem-relebactam MICs. Imipenem-relebactam (98.7% susceptible) showed similar activity to ceftazidime-avibactam (99.5% susceptible) and higher than ceftolozane-tazobactam (86.9% susceptible). Imipenem-relebactam was inactive against 1.3% (10/747) isolates, all of them due to carbapenemase production (9 K. pneumoniae and 1 E. cloacae). Imipenem-relebactam was active against 100% of extended-spectrum β-lactamase (ESBL)-E. coli and ESBL-Klebsiella spp. isolates and 80.4% of carbapenemase-Klebsiella spp. producers. Carbapenemase genes were confirmed by WGS in 41 Klebsiella spp.: OXA-48 (20/41), KPC-3 (14/41), OXA-181 (4/41), NDM-1 (1/41), OXA-48 + VIM-2 (1/41), and KPC-3 + VIM-2 (1/41). In Klebsiella spp. isolates, relebactam restored imipenem susceptibility in all KPC-3 producers, and resistant isolates (7/41) were mostly OXA-48 + CTX-M-15-K. pneumoniae high-risk clones (7/9). Intercountry differences were detected as follows: OXA-48 (17/21) was dominant in Spain, unlike KPC-3 (14/15) in Portugal. Imipenem-relebactam was 100% active against CTX-M-15-ST131-H30Rx-E. coli high-risk clone, predominant in both countries. Our results depict the potential role of imipenem-relebactam in ICU patients with cIAIs, cUTIs, and LRTIs due to wild-type ESBL- and carbapenemase-producing Enterobacterales, particularly KPC producers. IMPORTANCE We comparatively evaluate the in vitro activity of a drug combination consisting of a carbapenem (imipenem) and a novel inhibitor of beta-lactamases (relebactam), a mechanism that destroys beta-lactam antibiotics. We assess the activity against a collection of Enterobacterales clinical isolates recovered from difficult-to-treat infections in patients admitted to different intensive care units in Portugal and Spain. Imipenem-relebactam shows excellent activity in avoiding common resistance mechanisms in this setting, such as extended-spectrum beta-lactamases and carbapenemases widely distributed, including KPCs. We show few resistant isolates (

ObjectivesCARB-ES-19 is a comprehensive, multicenter, nationwide study integrating whole-genome sequencing (WGS) in the surveillance of carbapenemase-producing K. pneumoniae (CP-Kpn) and E. coli (CP-Eco) to determine their incidence, geographical distribution, phylogeny, and resistance mechanisms in Spain.MethodsIn total, 71 hospitals, representing all 50 Spanish provinces, collected the first 10 isolates per hospital (February to May 2019); CPE isolates were first identified according to EUCAST (meropenem MIC > 0.12 mg/L with immunochromatography, colorimetric tests, carbapenem inactivation, or carbapenem hydrolysis with MALDI-TOF). Prevalence and incidence were calculated according to population denominators. Antibiotic susceptibility testing was performed using the microdilution method (EUCAST). All 403 isolates collected were sequenced for high-resolution single-nucleotide polymorphism (SNP) typing, core genome multilocus sequence typing (cgMLST), and resistome analysis.ResultsIn total, 377 (93.5%) CP-Kpn and 26 (6.5%) CP-Eco isolates were collected from 62 (87.3%) hospitals in 46 (92%) provinces. CP-Kpn was more prevalent in the blood (5.8%, 50/853) than in the urine (1.4%, 201/14,464). The cumulative incidence for both CP-Kpn and CP-Eco was 0.05 per 100 admitted patients. The main carbapenemase genes identified in CP-Kpn were blaOXA–48 (263/377), blaKPC–3 (62/377), blaVIM–1 (28/377), and blaNDM–1 (12/377). All isolates were susceptible to at least two antibiotics. Interregional dissemination of eight high-risk CP-Kpn clones was detected, mainly ST307/OXA-48 (16.4%), ST11/OXA-48 (16.4%), and ST512-ST258/KPC (13.8%). ST512/KPC and ST15/OXA-48 were the most frequent bacteremia-causative clones. The average number of acquired resistance genes was higher in CP-Kpn (7.9) than in CP-Eco (5.5).ConclusionThis study serves as a first step toward WGS integration in the surveillance of carbapenemase-producing Enterobacterales in Spain. We detected important epidemiological changes, including increased CP-Kpn and CP-Eco prevalence and incidence compared to previous studies, wide interregional dissemination, and increased dissemination of high-risk clones, such as ST307/OXA-48 and ST512/KPC-3.

The emergence and spread of carbapenemase-producing gram-negative bacteria is a major public health concern. We used data collected from microbiology laboratories as part of the PIRASOA program during 2014–2018 to study the epidemiology of carbapenemase-producing bacteria in Andalusia, Spain. Our findings highlight the importance of ongoing surveillance and epidemiologic studies for these bacteria.

This study analyzes the pharmacokinetic variability of piperacillin in non-critically ill patients with Enterobacteriaceae bloodstream infections (EBSI) and explores predicted clinical outcomes and piperacillin-related neurotoxicity under different renal conditions. Hospitalized, non-critically ill patients treated with piperacillin–tazobactam for EBSI were included. Four serum samples per patient were collected and analyzed. A population pharmacokinetic model was developed using the Pmetrics package for R. Monte Carlo simulations of various dosage regimens of 4 g piperacillin, administered q8 h or q12 h by short (0.5 h) or long (4 h) infusion, following the different glomerular filtration rate (GFR) categories used to classify chronic kidney disease (Kidney Disease: Improving Global Outcomes, KDIGO) to determine the probability of target attainment (PTA) using a free drug concentrations above the minimal inhibitory concentration (fT > MIC) of 50% for efficacy and targets for piperacillin-associated neurotoxicity. Twenty-seven patients (102 samples) were included. Extended piperacillin infusions reached a PTA > 90% (50%fT > MIC) within the susceptibility range, although a loading dose did not greatly improve the expected outcome. Long infusions reduced the expected toxicity in patients with severe renal impairment. The study supports the use of extended infusions of piperacillin in non-critically ill patients with EBSI. No benefits of a loading dose were expected in our population. Finally, extended infusions may reduce the risk of toxicity in patients with severe renal impairment.

Although the failure of antibiotic treatment is normally attributed to resistance, tolerance and persistence display a significant role in the lack of response to antibiotics. Due to the fact that several nosocomial pathogens show a high level of tolerance and/or resistance to chlorhexidine, in this study we analyzed the molecular mechanisms associated with chlorhexidine adaptation in two clinical strains of Klebsiella pneumoniae by phenotypic and transcriptomic studies. These two strains belong to ST258-KPC3 (high-risk clone carrying β-lactamase KPC3) and ST846-OXA48 (low-risk clone carrying β-lactamase OXA48). Our results showed that the K. pneumoniae ST258-KPC3CA and ST846-OXA48CA strains exhibited a different behavior under chlorhexidine (CHLX) pressure, adapting to this biocide through resistance and tolerance mechanisms, respectively. Furthermore, the appearance of cross-resistance to colistin was observed in the ST846-OXA48CA strain (tolerant to CHLX), using the broth microdilution method. Interestingly, this ST846-OXA48CA isolate contained a plasmid that encodes a novel type II toxin/antitoxin (TA) system, PemI/PemK. We characterized this PemI/PemK TA system by cloning both genes into the IPTG-inducible pCA24N plasmid, and found their role in persistence and biofilm formation. Accordingly, the ST846-OXA48CA strain showed a persistence biphasic curve in the presence of a chlorhexidine-imipenem combination, and these results were confirmed by the enzymatic assay (WST-1).