Comparative analysis of a rapid diagnostic test and scoring tools for ESBL detection in Enterobacterales bloodstream infections for optimizing antimicrobial therapy.

IMPORTANCE: Our study addresses a significant issue in the medical and scientific community-the delayed administration of appropriate antimicrobial treatments due to the time-consuming process of phenotypic susceptibility data collection in gram-negative bloodstream infections. Our research indicates that a multiplex PCR rapid diagnostic test (RDT) significantly outperformed two clinical scoring tools in predicting ceftriaxone susceptibility. Multiplex PCR also led to reduced instances of undertreatment with ceftriaxone and minimized overtreatment with carbapenems. Furthermore, multiplex PCR demonstrated high sensitivity and specificity in predicting ceftriaxone susceptibility. The results of our study underscore the potential RDTs to reduce the time to appropriate antimicrobial therapy, leading to improved patient outcomes and reduced healthcare costs.

Emergence of cefiderocol resistance during ceftazidime/avibactam treatment caused by a large genomic deletion, including ampD and piuCD genes, in Pseudomonas aeruginosa.

We report the emergence of cefiderocol resistance during the treatment of a ST312 Pseudomonas aeruginosa respiratory infection with ceftazidime/avibactam. whole genome sequencing (WGS) revealed that resistance was caused by a large genomic deletion, including PiuDC (iron transport system) and AmpD (ampC negative regulator), driven by the integration of phage DNA. Thus, our findings alert that this type of deletion could be an efficient (two mechanisms in one step) specific cefiderocol resistance mechanism that might occur nonspecifically upon treatment with ß-lactams that select for AmpC overexpression.

Genotypic Evolution of Klebsiella pneumoniae Sequence Type 512 during Ceftazidime/Avibactam, Meropenem/Vaborbactam, and Cefiderocol Treatment, Italy.

In February 2022, a critically ill patient colonized with a carbapenem-resistant K. pneumoniae producing KPC-3 and VIM-1 carbapenemases was hospitalized for SARS-CoV-2 in the intensive care unit of Policlinico Umberto I hospital in Rome, Italy. During 95 days of hospitalization, ceftazidime/avibactam, meropenem/vaborbactam, and cefiderocol were administered consecutively to treat 3 respiratory tract infections sustained by different bacterial agents. Those therapies altered the resistome of K. pneumoniae sequence type 512 colonizing or infecting the patient during the hospitalization period. In vivo evolution of the K. pneumoniae sequence type 512 resistome occurred through plasmid loss, outer membrane porin alteration, and a nonsense mutation in the cirA siderophore gene, resulting in high levels of cefiderocol resistance. Cross-selection can occur between K. pneumoniae and treatments prescribed for other infective agents. K. pneumoniae can stably colonize a patient, and antimicrobial-selective pressure can promote progressive K. pneumoniae resistome evolution, indicating a substantial public health threat.

The scope of antimicrobial resistance in residential aged care facilities determined through analysis of Escherichia coli and the total wastewater resistome.

IMPORTANCE: Antimicrobial resistance (AMR) is a global threat that imposes a heavy burden on our health and economy. Residential aged care facilities (RACFs), where frequent inappropriate antibiotic use creates a selective environment that promotes the development of bacterial resistance, significantly contribute to this problem. We used wastewater-based epidemiology to provide a holistic whole-facility assessment and comparison of antimicrobial resistance in two RACFs and a retirement village. Resistant Escherichia coli, a common and oftentimes problematic pathogen within RACFs, was isolated from the wastewater, and the phenotypic and genotypic AMR was determined for all isolates. We observed a high prevalence of an international high-risk clone, carrying an extended-spectrum beta-lactamase in one facility. Analysis of the entire resistome also revealed a greater number of mobile resistance genes in this facility. Finally, both facilities displayed high fluoroquinolone resistance rates-a worrying trend seen globally despite measures in place aimed at limiting their use.

Prevalence and characterization of ESBL-producing Escherichia coli in healthy pregnant women and hospital environments in Benin: an approach based on Tricycle.

Introduction: Extended-Spectrum Beta-Lactamase (ESBL)-producing Enterobacterales are recognized as significant pathogens due to their resistance to multiple antibiotics. This study aimed to determine the prevalence of ESBL-producing Escherichia coli (E. coli) in different settings, including healthy pregnant women, the food chain, and the environment of tertiary hospitals in Benin. Methods: Samples were collected from various sources, including fecal samples from healthy pregnant women, food samples from hospital canteens, and hospital effluents from four tertiary hospitals in southern Benin. Fecal samples were plated on MacConkey agar supplemented with cefotaxime (4 µg/mL), while food and water samples were plated on Tryptone Bile X agar supplemented with cefotaxime (4 µg/mL). Urea indole tests were used for preliminary identification of E. coli colonies, followed by confirmation of ESBL production using the double disk synergy technique. Antibiotic susceptibility testing of ESBL-producing E. coli strains was conducted using the disk diffusion method on MH agar. Polymerase Chain Reaction (PCR) was used to investigate the presence of ESBL-encoding genes. Results: Among the 296 fecal samples collected from four tertiary hospitals, ESBL-producing E. coli was isolated from 22.30% (66) of the samples. All E. coli isolates from hospital effluents exhibited ESBL production, while ESBL-producing E. coli was not detected in food and drinking water samples. The analysis of variable associations showed no significant associations (p > 0.05) for the studied factors. Antibiotic susceptibility testing revealed high resistance rates among the ESBL-Ec isolates against several tested antibiotics, including amoxicillin, aztreonam, ceftriaxone, ciprofloxacin, and trimethoprim-sulfamethoxazole. However, most isolates remained susceptible to ertapenem, amoxicillin-clavulanate, and imipenem. The most prevalent ESBL-encoding genes were blaTEM (37.50%), blaOXA-1 (19.44%), and blaSHV (11.11%), while a smaller proportion of isolates carried blaCTXM-1/blaCTXM-15 (5.55%) and blaCTXM-9. Discussion: This study provides insights into the prevalence of ESBL-producing E. coli carriage in the feces of healthy pregnant women in southern Benin. Additionally, it highlights hospital wastewater as a potential reservoir of ESBL-producing bacteria in the environment. The detection of ESBL-producing E. coli in hospital effluents raises concerns about the dissemination of antibiotic resistance genes into the environment. The high resistance rates observed among ESBL-Ec isolates against commonly used antibiotics emphasize the urgent need for antimicrobial stewardship and infection control measures. The identification of prevalent ESBL-encoding genes contributes to understanding the genetic basis of ESBL resistance in the studied population. Further research is warranted to explore the mechanisms of transmission and potential interventions to mitigate the spread of ESBL-producing Enterobacterales.

Expulsion of plasmid-mediated antibiotic resistance genes in E. coli by ethidium bromide and acridine orange treatment.

Plasmid borne antibiotics resistance is the global threat to healthcare facilities. Such antibiotics resistance is inherited stably within the same bacterial generations and transmitted horizontally to other species of bacteria. The elimination of such resistance plasmid is of great importance to contain dispersal of antibiotics resistance. E. coli strains were identified, screened for the presence of antibiotics resistance by disc diffusion method, and cured by sub-lethal concentrations of Ethidium bromide and Acridine orange. After curing, again antibiotic resistance was determined. Before and after curing, plasmids were extracted by column spin Kit and subjected to 1% agarose gel electrophoresis and antibiotic resistance genes were identified by PCR. The Ethidium bromide was more effective than Acridine orange in eliminating antibiotics resistance and resistance genes bearing plasmids (4, 5, 6, 8, 9, 10 and <10kb). The most frequently eliminated antibiotic resistance was against Imipenem and Meropenem followed by Cefoperazone-sulbactam, Amikacin and cephalosporins in sequence. The loss of antibiotic resistance was associated with the elimination of plasmid-borne antibiotic resistance genes; bla-TEM, bla-SHV, bla-CTX-M, qnrA, qnrB, qnrC and qnrD. Some E. coli strains did not show the removal of antibiotics resistance and plasmids, suggesting the presence of resistance genes on main chromosome and or non-curable plasmids.

Abundance and prevalence of ESBL coding genes in patients undergoing first line eradication therapy for Helicobacter pylori.

The spread of extended-spectrum beta-lactamases (ESBLs) in nosocomial and community-acquired enterobacteria is an important challenge for clinicians due to the limited therapeutic options for infections that are caused by these organisms. Here, we developed a panel of ESBL coding genes, evaluated the abundance and prevalence of ESBL encoding genes in patients undergoing H. pylori eradication therapy, and summarized the effects of eradication therapy on functional profiles of the gut microbiome. To assess the repertoire of known beta lactamase (BL) genes, they were divided into clusters according to their evolutionary relation. Primers were designed for amplification of cluster marker regions, and the efficiency of this amplification panel was assessed in 120 fecal samples acquired from 60 patients undergoing H. pylori eradication therapy. In addition, fecal samples from an additional 30 patients were used to validate the detection efficiency of the developed ESBL panel. The presence for majority of targeted clusters was confirmed by NGS of amplification products. Metagenomic sequencing revealed that the abundance of ESBL genes within the pool of microorganisms was very low. The global relative abundances of the ESBL-coding gene clusters did not differ significantly among treatment states. However, at the level of each cluster, classical ESBL producers such as Klebsiella sp. for blaOXY (p = 0.0076), Acinetobacter sp. for blaADC (p = 0.02297) and others, differed significantly with a tendency to decrease compared to the pre- and post-eradication states. Only 13 clusters were common across all three datasets, suggesting a patient-specific distribution profile of ESBL-coding genes. The number of AMR genes detected in the post-eradication state was higher than that in the pre-eradication state, which could be attributed, at least in part, to the therapy. This study demonstrated that the ESBL screening panel was effective in targeting ESBL-coding gene clusters from bacterial DNA and that minor differences exist in the abundance and prevalence of ESBL-coding gene levels before and after eradication therapy.

Induced Heteroresistance in Carbapenem-Resistant Acinetobacter baumannii (CRAB) via Exposure to Human Pleural Fluid (HPF) and Its Impact on Cefiderocol Susceptibility.

Infections caused by Carbapenem-resistant Acinetobacter baumannii (CRAB) isolates, such as hospital-acquired pneumonia (HAP), bacteremia, and skin and soft tissue infections, among others, are particularly challenging to treat. Cefiderocol, a chlorocatechol-substituted siderophore antibiotic, was approved by the U.S. Food and Drug Administration (FDA) in 2019 and prescribed for the treatment of CRAB infections. Despite the initial positive treatment outcomes with this antimicrobial, recent studies reported a higher-than-average all-cause mortality rate in patients treated with cefiderocol compared to the best available therapy. The cause(s) behind these outcomes remains unconfirmed. A plausible hypothesis is heteroresistance, a phenotype characterized by the survival of a small proportion of cells in a population that is seemingly isogenic. Recent results have demonstrated that the addition of human fluids to CRAB cultures leads to cefiderocol heteroresistance. Here, we describe the molecular and phenotypic analyses of CRAB heteroresistant bacterial subpopulations to better understand the nature of the less-than-expected successful outcomes after cefiderocol treatment. Isolation of heteroresistant variants of the CRAB strain AMA40 was carried out in cultures supplemented with cefiderocol and human pleural fluid (HPF). Two AMA40 variants, AMA40 IHC1 and IHC2, were resistant to cefiderocol. To identify mutations and gene expression changes associated with cefiderocol heteroresistance, we subjected these variants to whole genome sequencing and global transcriptional analysis. We then assessed the impact of these mutations on the pharmacodynamic activity of cefiderocol via susceptibility testing, EDTA and boronic acid inhibition analysis, biofilm formation, and static time-kill assays. Heteroresistant variants AMA40 IHC1 and AMA40 IHC2 have 53 chromosomal mutations, of which 40 are common to both strains. None of the mutations occurred in genes associated with high affinity iron-uptake systems or ß-lactam resistance. However, transcriptional analyses demonstrated significant modifications in levels of expression of genes associated with iron-uptake systems or ß-lactam resistance. The blaNDM-1 and blaADC-2, as well as various iron-uptake system genes, were expressed at higher levels than the parental strain. On the other hand, the carO and ompA genes' expression was reduced. One of the mutations common to both heteroresistant strains was mapped within ppiA, a gene associated with iron homeostasis in other species. Static time-kill assays demonstrated that supplementing cation-adjusted Mueller-Hinton broth with human serum albumin (HAS), the main protein component of HPF, considerably reduced cefiderocol killing activity for all three strains tested. Notably, collateral resistance to amikacin was observed in both variants. We conclude that exposing CRAB to fluids with high HSA concentrations facilitates the rise of heteroresistance associated with point mutations and transcriptional upregulation of genes coding for ß-lactamases and biofilm formation. The findings from this study hold significant implications for understanding the emergence of CRAB resistance mechanisms against cefiderocol treatment. This understanding is vital for the development of treatment guidelines that can effectively address the challenges posed by CRAB infections.

Compassionate use of a novel ß-lactam enhancer-based investigational antibiotic cefepime/zidebactam (WCK 5222) for the treatment of extensively-drug-resistant NDM-expressing Pseudomonas aeruginosa infection in an intra-abdominal infection-induced sepsis patient: a case report.

Infections in critically-ill patients caused by extensively-drug-resistant (XDR)-Pseudomonas aeruginosa are challenging to manage due to paucity of effective treatment options. Cefepime/zidebactam, which is currently in global Phase 3 clinical development (Clinical Trials Identifier: NCT04979806, registered on July 28, 2021) is a novel mechanism of action based ß-lactam/ ß-lactam-enhancer combination with a promising activity against a broad-range of Gram-negative pathogens including XDR P. aeruginosa. We present a case report of an intra-abdominal infection-induced sepsis patient infected with XDR P. aeruginosa and successfully treated with cefepime/zidebactam under compassionate use. The 50 year old female patient with past-history of bariatric surgery and recent elective abdominoplasty and liposuction developed secondary pneumonia and failed a prolonged course of polymyxins. The organism repeatedly isolated from the patient was a New-Delhi metallo ß-lactamase-producing XDR P. aeruginosa resistant to ceftazidime/avibactam, imipenem/relebactam and ceftolozane/tazobactam, susceptible only to cefepime/zidebactam. As polymyxins failed to rescue the patient, cefepime/zidebactam was administered under compassionate grounds leading to discharge of patient in stable condition. The present case highlights the prevailing precarious scenario of antimicrobial resistance and the need for novel antibiotics to tackle infections caused by XDR phenotype pathogens.

Proteus mirabilis - analysis of a concealed source of carbapenemases and development of a diagnostic algorithm for detection.

OBJECTIVES: To analyse carbapenemases in Proteus mirabilis and assess the performance of carbapenemase detection assays. METHODS: Eighty-one clinical P. mirabilis isolates with high-level resistance at least to ampicillin (>32 mg/L) or previous detection of carbapenemases were selected and investigated by three susceptibility testing methods (microdilution, automated susceptibility testing, and disk diffusion), six phenotypic carbapenemase assays (CARBA NP, modified carbapenemase inactivation method [CIM], modified zinc-supplemented CIM, simplified CIM, faropenem, and carbapenem-containing agar), two immunochromatographic assays, and whole-genome sequencing. RESULTS: Carbapenemases were detected in 43 of 81 isolates (OXA-48-like [n = 13]; OXA-23 [n = 12]; OXA-58 [n = 12]; New Delhi metallo-ß-lactamase (NDM) [n = 2]; Verona integron-encoded metallo-ß-lactamase (VIM) [n = 2]; Imipenemase (IMP) [n = 1]; Klebsiella pneumoniae carbapenemase (KPC) [n = 1]). Carbapenemase-producing Proteus were frequently susceptible to ertapenem (26/43; 60%), meropenem (28/43; 65%), ceftazidime (33/43; 77%), and some even to piperacillin-tazobactam (9/43; 21%). Sensitivity/specificity of phenotypic tests were 30% (CI: 17-46%)/89% (CI: 75-97%) for CARBA NP, 74% (CI: 60-85%)/82% (CI: 67-91%) for faropenem, 91% (CI: 78-97%)/82% (CI: 66-92%) for simplified CIM, and 93% (CI: 81-99%)/100% (CI: 91-100%) for modified zinc-supplemented CIM. An algorithm for improved detection was developed, which demonstrated sensitivity/specificity of 100% (CI: 92-100%)/100% (CI: 91-100%) on the 81 isolates, and 100% (CI: 29-100%)/100% (CI: 96-100%) in a prospective analysis of additional 91 isolates. Interestingly, several OXA-23-producing isolates belonged to the same clonal lineage reported previously from France. DISCUSSION: Current susceptibility testing methods and phenotypic tests frequently fail to detect carbapenemases in P. mirabilis, which could result in inadequate antibiotic treatment. In addition, the non-inclusion of blaOXA-23/OXA-58 in many molecular carbapenemase assays further impedes their detection. Therefore, the prevalence of carbapenemases in P. mirabilis is likely underestimated. With the herein proposed algorithm, carbapenemase-producing Proteus can be easily identified.

Case Commentary: When Voldemort Meets Sauron: Treatment Considerations for Emerging Dual-Carbapenemase-Producing Extensively Drug-Resistant Pseudomonas aeruginosa.

Infections caused by extensively drug-resistant Pseudomonas aeruginosa are difficult to treat due to limited effective treatment options. In this issue, a patient with a corneal infection caused by a Verona integron-encoded metallo-ß-lactamase (VIM)- and Guiana extended-spectrum ß-lactamase (GES)-coproducing P. aeruginosa strain associated with the recent artificial tears-related outbreak in the United States is described. This resistance genotype/phenotype further compromises therapeutic options, and this report provides insights into diagnostic and treatment approaches for clinicians dealing with infections due to this highly resistant P. aeruginosa.

Successful Use of Cefepime-Zidebactam (WCK 5222) as a Salvage Therapy for the Treatment of Disseminated Extensively Drug-Resistant New Delhi Metallo-ß-Lactamase-Producing Pseudomonas aeruginosa Infection in an Adult Patient with Acute T-Cell Leukemia.

With limited and often toxic treatment options, carbapenem-resistant Gram-negative infections are associated with significant mortality. Cefepime-zidebactam is a promising antibiotic option undergoing a phase 3 trial that has activity against diverse antibiotic-resistant mechanisms in Gram-negative pathogens due to its ß-lactam enhancer mechanism, mediating multiple PBP binding. We report a case of disseminated infection caused by a New Delhi metallo-ß-lactamase-producing, extensively drug-resistant Pseudomonas aeruginosa isolate in a patient with acute T-cell leukemia, successfully managed with cefepime-zidebactam as a salvage therapy.

Dissemination of carbapenemase-producing Enterobacterales through wastewater and gulls at a wastewater treatment plant in Sweden.

Here we report the detection of carbapenemase-producing Enterobacterales (CPE) isolated from Swedish wastewater and gull faeces. CPE have not been detected in samples from animals in Sweden preceding this report. Sampling of wastewater treatment plant (WWTP) inlet and outlet, sedimentation basins, surface seawater from key aquatic bird habitats and freshly deposited gull faeces was done on six separate occasions during May to September 2021. Following broth enrichment, selective screening of putative CPE was performed on mSuperCarba™ (CHROMagar). Species identification was done with MALDI-TOF. Antimicrobial susceptibility testing was performed according to EUCAST. In total, seventeen CPE were verified by genome sequencing carrying blaGES-5, blaIMI-3, blaOXA-181 or blaOXA-244. The blaGES-5 was carried on IncP plasmids in four different species; Escherichia coli ST10 isolated from WWTP outlet, Raoultella ornithinolytica isolated from WWTP inlet, outlet and sedimentation basins as well as gull faeces collected at the WWTP and Klebsiella spp. isolates from WWTP inlet and outlet. The genetic environment surrounding blaGES-5 was similar in two Citrobacter freundii causing human infections. The blaIMI-3 was carried on IncFII(Yp) plasmids in four Enterobacter ludwigii, isolated from WWTP outlet and gull faeces collected at a recreational city park 2 km from the WWTP. The blaOXA-181 was located on a COLKP3 plasmid found in an E. coli, while blaOXA-244 was chromosomally located in an E. coli ST10, both isolated from WWTP inlet. Phylogenetic analysis of R. ornithinolytica and E. ludwigii isolates indicate that the gulls carried strains related to those identified in the WWTP samples. The results thus add to the increasing evidence of WWTPs as anthropogenic reservoirs for mobile genetic elements with antibiotic-resistance functionality. Such environments could profoundly impact the dissemination and spread of such genetic elements via for example aquatic birds, thereby warranting further study and surveillance.

Comparative Activities of Novel Therapeutic Agents against Molecularly Characterized Clinical Carbapenem-Resistant Enterobacterales Isolates.

Limited treatment options exist for the treatment of carbapenem-resistant Enterobacterales (CRE) bacteria. Fortunately, there are several recently approved antibiotics indicated for CRE infections. Here, we examine the in vitro activity of various novel agents (eravacycline, plazomicin, ceftazidime-avibactam, imipenem-relebactam, and meropenem-vaborbactam) and comparators (tigecycline, amikacin, levofloxacin, fosfomycin, polymyxin B) against 365 well-characterized CRE clinical isolates with various genotypes. Nonduplicate isolates collected from the largest public health hospital in Singapore between 2007 and 2020 were subjected to antimicrobial susceptibility testing (broth microdilution or antibiotic gradient test strips). Susceptibilities were defined using Clinical and Laboratory Standards Institute (CLSI) or Food and Drug Administration (FDA) interpretative criteria. Sequence types and resistance mechanisms were characterized using short-read whole-genome sequencing. Overall, tigecycline and plazomicin exhibited the highest susceptibility rates (89.6% and 80.8%, respectively). However, the tigecycline susceptibility breakpoint utilized here may be outdated in view of prevailing pharmacokinetic-pharmacodynamic (PK/PD) data. Susceptibility varied by carbapenemase genotype; the ß-lactam/ß-lactamase inhibitor combinations were equally active (92.3 to 99.2% susceptible) against KPC producers, but only ceftazidime-avibactam retained high susceptibility (98.7%) against OXA-48-like producers. Against metallo-ß-lactamase producers, only plazomicin exhibited moderate activity (77.0% susceptible). Aminoglycoside activity was also influenced by carbapenemase genotypes. This work provides an insight into the comparative activity and presumptive utility of novel agents in this geographic region. IMPORTANCE This study determined the susceptibilities of carbapenem-resistant Enterobacterales isolates to various novel antimicrobial agents (ceftazidime-avibactam, imipenem-relebactam, meropenem-vaborbactam, eravacycline, and plazomicin). Whole-genome sequencing was performed for all strains. Our study findings provide insights into the comparative activities of novel agents in this geographic region. Plazomicin and ceftazidime-avibactam exhibited the lowest nonsusceptibility rates and may be considered promising agents in the management of carbapenem-resistant Enterobacterales infections. We note also that antibiotic activity is influenced by genotypes and that understanding the geographic region's molecular epidemiology could aid in the definition of the presumptive utility of novel agents and contribute to antibiotic decision-making.

Identification of an Outbreak Cluster of Extensively Antibiotic-Resistant GC1 Acinetobacter baumannii Isolates in U.S. Military Treatment Facilities.

An outbreak involving an extensively antibiotic-resistant Acinetobacter baumannii strain in three military treatment facilities was identified. Fifty-nine isolates recovered from 30 patients over a 4-year period were found among a large collection of isolates using core genome multilocus sequence typing (MLST). They differed by only 0 to 18 single nucleotide polymorphisms (SNPs) and carried the same resistance determinants except that the aphA6 gene was missing in 25 isolates. They represent a novel sublineage of GC1 lineage 1 that likely originated in Afghanistan. IMPORTANCE A. baumannii is recognized as one of the most important nosocomial pathogens, and carbapenem-resistant strains pose a particularly difficult treatment challenge. Outbreaks linked to this pathogen are reported worldwide, particularly during periods of societal upheaval, such as natural disasters and conflicts. Understanding how this organism enters and establishes itself within the hospital environment is key to interrupting transmission, but few genomic studies have examined these transmissions over a prolonged period. Though historical, this report provides an in-depth analysis of nosocomial transmission of this organism across continents and within and between different hospitals.

Foodborne Outbreak of Extended Spectrum Beta-lactamase Producing Shigella sonnei Associated with Contaminated Spring Onions in the United Kingdom.

Globalization of the food supply chain has created conditions favorable for emergence and spread of multidrug-resistant (MDR) foodborne pathogens. In November 2021, the UK Health Security Agency detected an outbreak of 17 cases infected with the same strain of MDR extended spectrum beta-lactamase (ESBL)-producing Shigella sonnei. Phylogenetic analysis of whole-genome sequencing data revealed the outbreak was closely related to strains of S. sonnei isolated from travelers returning to the UK from Egypt. None of the outbreak cases reported travel and all 17 cases reported eating food from a restaurant/food outlet in the week prior to symptom onset, of which 11/17 (64.7%) ate at branches of the same national restaurant franchise. All 17 cases were adults and 14/17 (82.4%) were female. Ingredient-level analyses of the meals consumed by the cases identified spring onions as the common ingredient. Food chain investigations revealed that the spring onions served at the implicated restaurants could be traced back to a single Egyptian producer. The foodborne transmission of ESBL-producing bacteria is an emerging global health concern, and concerted action from all stakeholders is required to ensure an effective response to mitigate the risks to public health.

High prevalence of Escherichia coli co-harboring conjugative plasmids with colistin- and carbapenem resistance genes in a wastewater treatment plant in China.

Emergence and dissemination of resistance to last-resort antibiotics such as carbapenem and colistin is a growing, global health concern. Wastewater treatment plants (WWTPs) link human activities and the environment, can act as reservoirs and sources for emerging antibiotic resistance, and likely play a large role in antibiotic resistance transmission. The aim of this study was to investigate occurrence and characteristics of colistin- and carbapenem-resistant Escherichia coli (CCREC) in wastewater and sludge samples collected over a one-year period from different functional areas of an urban WWTP in Jinan city, Shandong, China. A total of 8 CCREC were isolated from 168 samples with selective agar and PCR, corresponding to high prevalence of 4.8%, co-harboring carbapenem resistance genes (blaNDM) and colistin resistance gene (mcr-1) and subsequently whole-genome sequenced. Additionally, all isolates were multidrug-resistant by antimicrobial susceptibility testing and carried a variety of antibiotic resistance genes. Two isolates carrying virulence genes associated with avian pathogenic E. coli were identified, one belonging to the high-risk clone O101:H9-ST167. Southern blotting was used to characterize CCREC isolates and plasmids carrying blaNDM-genes or mcr-1 could be transferred to a recipient strain E. coli J53 by in vitro conjugation assays. Resistance to other antibiotic classes were sporadically co-transferred to the transconjugant. Transposition of and mcr-1-carrying element from a transferable IncHI2-plasmid was observed among two CCREC clones isolated within 4 days of each other. The occurrence of multidrug-resistant CCREC capable of transferring their antibiotic resistance genotypes via conjugative plasmids is alarming. WWTPs bring bacteria from different sources together, providing opportunities for horizontal exchange of DNA among compatible hosts. Further dissemination of the colistin-, carbapenem-, or both colistin- and carbapenem resistant E. coli could lead to a serious threat to public health.

Colonization by ceftazidime/avibactam-resistant KPC-producing Klebsiella pneumoniae following therapy in critically ill patients.

OBJECTIVES: Ceftazidime-avibactam (CAZ-AVI)-based treatments have been associated with the emergence of resistance in KPC-producing Klebsiella pneumoniae (KPC-Kp) isolates after antimicrobial exposure. Here, we evaluated the CAZ-AVI resistance development in KPC-Kp isolated from patients treated with CAZ-AVI-based therapy. METHODS: We enrolled adult patients treated with CAZ-AVI-based regimens between January 2020 and January 2021. Carbapenemase-producing isolates collected from clinical samples and rectal swabs were evaluated for CAZ-AVI resistance development after antimicrobial exposure. KPC-Kp developing CAZ-AVI resistance and parental susceptible strains were genomically characterized. Whole genome sequencing was performed by using the Illumina iSeq100 platform and genomes were analyzed for antimicrobial-resistance genes, plasmid and porins sequences. RESULTS: We enrolled 90 patients treated with CAZ-AVI-based therapy and 62.2% (56/90) of them were colonized by KPC-producers before CAZ-AVI-based treatment and 6.6% acquired colonization during therapy. Six (6.6%) patients developed infections because of resistant KPC-Kp after CAZ-AVI exposure and 3 (3.3%) of them developed CAZ-AVI resistance in the rectum. Development of resistance among KPC in the rectum occurred after 32 (IQR, 9-35) days of therapy and after 30 (IQR, 22-40) days in clinical specimens. Genetic analysis demonstrated that the development of CAZ-AVI resistance was associated with mutated blaKPC-3 (blaKPC-31, blaKPC-53, blaKPC-89, and blaKPC-130) and phylogenetic analysis demonstrated a close genomic relationship between KCP-Kp collected from rectum and clinical samples of the same patient. DISCUSSION: Antimicrobial exposure induce a higher incidence of CAZ-AVI resistance development in the blood and respiratory tract than in the rectum (6.7% vs. 3.3%) of CAZ-AVI-treated patients and genome analysis showed that resistance was associated with mutated blaKPC-3 variants.

Baicalein Inhibits Plasmid-Mediated Horizontal Transmission of the blaKPC Multidrug Resistance Gene from Klebsiella pneumoniae to Escherichia coli.

Carbapenem-resistant bacterial infections pose an urgent threat to public health worldwide. Horizontal transmission of the ß-lacatamase Klebsiella pneumoniae carbapenemase (blaKPC) multidrug resistance gene is a major mechanism for global dissemination of carbapenem resistance. Here, we investigated the effects of baicalein, an active ingredient of a Chinese herbal medicine, on plasmid-mediated horizontal transmission of blaKPC from a meropenem-resistant K. pneumoniae strain (JZ2157) to a meropenem-sensitive Escherichia coli strain (E600). Baicalein showed no direct effects on the growth of JZ2157 or E600. Co-cultivation of JZ2157 and E600 caused the spread of meropenem resistance from JZ2157 to E600. Baicalein at 40 and 400 µg/mL significantly inhibited the spread of meropenem resistance. Co-cultivation also resulted in plasmid-mediated transmission of blaKPC from JZ2157 to E600, which was inhibited by baicalein. Therefore, baicalein may be used in clinical practice to prevent or contain outbreaks of carbapenem-resistant infections by inhibiting the horizontal transfer of resistance genes across bacteria species.