Impact of ceftazidime-avibactam treatment in the emergence of novel KPC variants in ST307-Klebsiella pneumoniae high-risk clone and consequences for their routine detection

Occurrence of multi-carbapenemase-producing Enterobacterales in a tertiary hospital in Madrid (Spain): a new epidemiologic scenario

INTRODUCTION

Multi-carbapenemase-producing Enterobacterales (M-CPE) are increasingly described. We characterized the M-CPE isolates prospectively recovered in our hospital (Madrid, Spain) over two years (2021-2022).

METHODS

We collected 796 carbapenem resistant Enterobacterales (CRE) from clinical and surveillance samples. Carbapenemase production was confirmed with phenotypic (immunochromatographic, disk diffusion) and molecular (PCR, WGS) techniques. Antimicrobial susceptibility was evaluated by a standard broth microdilution method. Clinical and demographic data were collected.

RESULTS

Overall, 23 M-CPE (10 Klebsiella pneumoniae, 6 Citrobacter freundii complex, 3 Escherichia coli, 2 Klebsiella oxytoca, and 2 Enterobacter hormaechei) isolates were recovered from 17 patients (3% with CPE, 0.27 cases per 1000 admissions). OXA-48+KPC-3 (7/23) and KPC-3+VIM-1 (5/23) were the most frequent carbapenemase combinations. All patients had prior antibiotics exposure, including carbapenems (8/17). High resistance rates to ceftazidime/avibactam (14/23), imipenem/relebactam (16/23) and meropenem/vaborbactam (7/23) were found. Ceftazidime/avibactam+aztreonam combination was synergistic in all metallo-β-lactamase producers. Clonal and non-clonal related isolates were found, particularly in K. pneumoniae (5 ST29, 3 ST147, 3 ST307) and C. freundii (3 ST8, 2 ST125, 1 ST563). NDM-1+OXA-48 was introduced with the ST147-K. pneumoniae high-risk clone linked to the transfer of an Ukrainian patient. We identified four possible nosocomial clonal transmission events between patients of the same clone with the same combination of carbapenemases (KPC-3+VIM-1-ST29-K. pneumoniae, NDM-1+OXA-48-ST147-K. pneumoniae and KPC-2+VIM-1-ST145-K. oxytoca). Carbapenemase-encoding genes were located on different plasmids, except for VIM-1+KPC-2-ST145-K. oxytoca. Cross-species transmission and a possible acquisition overtime was found, particularly between K. pneumoniae and E. coli producing OXA-48+KPC-3.

CONCLUSION

M-CPE is an emerging threat in our hospital. Co-production of different carbapenemases, including metallo-β-lactamases, limits therapeutic options and depicts the need to reinforce infection control measures.

Within-host transition to GES-55 during a GES-6-producing Serratia marcescens outbreak: Emergence of ceftazidime-avibactam resistance and increased susceptibility to carbapenems

OBJECTIVES

To describe the in vivo emergence of ceftazidime-avibactam resistance in GES-type carbapenemases and to characterize an unusual outbreak of GES-6-producing Serratia marcescens during the COVID-19 pandemic in Spain.

METHODS

Retrospective study to describe a GES-CPSM outbreak based on whole genome sequencing and antimicrobial susceptibility testing (AST). Transferability of blaGES-carrying plasmid was assessed by conjugation experiments.

RESULTS

In December 2020, we identified a cluster of S. marcescens harbouring blaGES-6 involving 9 patients. Whole-genome sequence analysis revealed a clonal relationship (≤3 SNPs) between the first isolates identified in each of the evolved patients and environmental samples with GES-CPSM detection. Plasmid analysis showed that the blaGES-6 gene was located in an IncQ3-type plasmid. Triparental mating experiments using a helper plasmid demonstrated mobilization of the blaGES-6-carrying plasmid. Our results also demonstrate within-host evolution in S. marcescens isolates, leading to a transition from blaGES-6 to the new blaGES-55, caused by the P162S mutation, in a subsequent infection in one of the affected patients. In blaGES-55 we identified emergence of ceftazidime-avibactam resistance along with an increase of carbapenems susceptibility. This patient had been treated with a 14-day course of ceftazidime-avibactam. AST of the transformants bearing blaGES-6 and blaGES-55 plasmids, confirmed susceptibility variation affecting ceftazidime-avibactam and carbapenems.

CONCLUSIONS

We report an unusual outbreak of GES-6 whose incidence is becoming increasing. Transition from GES-6 to GES-55 may readily occur in vivo leading to ceftazidime-avibactam resistance, which brings to the fore the critical need for developing more accurate diagnosis tools for detection of GES β-lactamases and optimise the use of antimicrobials.

Complete Genome Sequence of a Klebsiella pneumoniae Strain Carrying Novel Variant blaKPC-203, Cross-Resistant to Ceftazidime/Avibactam and Cefiderocol, but Susceptible to Carbapenems, Isolated in Italy, 2023

BACKGROUND

Klebsiella pneumoniae is a concerning pathogen, responsible for hospital-associated outbreaks. Multi drug resistant (MDR) strains are especially hard to treat. We conducted whole-genome sequencing on a MDR K. pneumoniae strain in order to identify genomic features potentially linked to its phenotype.

METHODS

DNA sequencing was performed on the Illumina iSeq 100 platform. Genome assembly was carried out with SPAdes. The genome was annotated with RASTtk. Typing was performed with MLST and Kaptive. Antibiotic resistance genes were detected with AMRFinderPlus and Abricate, and further verified with BLAST.

RESULTS

The strain exhibited resistance to ceftazidime/avibactam and cefiderocol, but remained susceptible to carbapenems. The strain belonged to sequence type ST101, serotype O1:K17. The analysis of antibiotic resistance genes indicated that the strain carried a novel KPC variant, designated as KPC-203, featuring a EL deletion at amino acid position 166-167, within the Ω-loop, and a nine-amino-acid insertion (LAVYTRAPM) at position 259. Sequence alterations were found in porin genes ompK35 and ompK36. Unlike molecular testing, which was able to detect the KPC-203 variant, all phenotypic carbapenemase detection methods achieved negative results.

CONCLUSIONS

KPC-203, a novel KPC variant, showed a sequence modification in a cephalosporin resistance-associated hotspot. Interestingly, such alterations typically correlate with the restoration of carbapenem susceptibility. We hypothesize that KPC-203 likely led to resistance to ceftazidime/avibactam and cefiderocol, while maintaining susceptibility to carbapenems.

International and regional spread of carbapenem-resistant Klebsiella pneumoniae in Europe

Carbapenem-resistant Klebsiella pneumoniae (CRKP) are of particular concern due to the spread of antibiotic resistance genes associated with mobile genetic elements. In this study, we collected 687 carbapenem-resistant strains recovered among clinical samples from 41 hospitals in nine Southern European countries (2016-2018). We identified 11 major clonal lineages, with most isolates belonging to the high-risk clones ST258/512, ST101, ST11, and ST307. blaKPC-like was the most prevalent carbapenemase-encoding gene (46%), with blaOXA-48 present in 39% of isolates. Through the combination and comparison of this EURECA collection with the previous EuSCAPE collection (2013-2014), we investigated the spread of high-risk clones circulating in Europe exhibiting regional differences. We particularly found blaKPC-like ST258/512 in Greece, Italy, and Spain, blaOXA-48 ST101 in Serbia and Romania, blaNDM ST11 in Greece, and blaOXA-48-like ST14 in Türkiye. Genomic surveillance across Europe thus provides crucial insights for local risk mapping and informs necessary adaptions for implementation of control strategies.

First report of KPC variants conferring ceftazidime-avibactam resistance in Colombia: introducing KPC-197

Resistance to ceftazidime-avibactam (CZA) due to Klebsiella pneumoniae carbapenemase (KPC) variants is increasing worldwide. We characterized two CZA-resistant clinical Klebsiella pneumoniae strains by antimicrobial susceptibility test, conjugation assays, and WGS. Isolates belonged to ST258 and ST45, and produced a KPC-31 and a novel variant KPC-197, respectively. The novel KPC variant presents a deletion of two amino acids on the Ω-loop (del_168-169_EL) and an insertion of two amino acids in position 274 (Ins_274_DS). Continued surveillance of KPC variants conferring CZA resistance in Colombia is warranted.

IMPORTANCE

Latin America and the Caribbean is an endemic region for carbapenemases. Increasingly high rates of Klebsiella pneumoniae carbapenemase (KPC) have established ceftazidime-avibactam (CZA) as an essential antimicrobial for the treatment of infections due to MDR Gram-negative pathogens. Although other countries in the region have reported the emergence of CZA-resistant KPC variants, this is the first description of such enzymes in Colombia. This finding warrants active surveillance, as dissemination of these variants could have devastating public health consequences.

Detection of KPC-216, a Novel KPC-3 Variant, in a Clinical Isolate of Klebsiella pneumoniae ST101 Co-Resistant to Ceftazidime-Avibactam and Cefiderocol

BACKGROUND

Carbapenemase-producing Klebsiella pneumoniae (CP-KP) represents a global threat to public health, with limited antimicrobial therapeutic options. In this study, we analyzed a ceftazidime/avibactam (CAZ-AVI)-resistant K. pneumoniae isolate obtained from a patient previously exposed to CAZ-AVI expressing a novel K. pneumoniae carbapenemase (KPC)-3 variant.

METHODS

Antimicrobial susceptibility testing was performed using reference broth microdilution. Whole-genome sequencing (WGS) was performed using Illumina and Nanopore Technologies. Short- and long-reads were combined with Unicycler. Assemblies were investigated for multilocus sequence typing (MLST), antimicrobial resistance genes, porins, and plasmids.

RESULTS

The K. pneumoniae isolate (KP_RM_1) was resistant to CAZ-AVI, expanded-spectrum cephalosporins, amikacin, ertapenem, and cefiderocol (FDC) but was susceptible to tigecycline, colistin, trimethoprim/sulfamethoxazole, meropenem-vaborbactam, and imipenem-relebactam. WGS revealed that the KP_RM_1 genome is composed of a single chromosome of 5 Mbp and five circular plasmids. Further analysis showed the presence of novel blaKPC-216 located on a 72 kb plasmid. KPC-216 differs from KPC-3 by a Lysin (K) insertion at position 168 (+K168).

CONCLUSIONS

We report the identification of a new KPC-3 variant associated with CAZ-AVI resistance. The KPC variants associated with CAZ-AVI resistance should be determined to promptly inform clinicians and start the appropriate antimicrobial therapy.

Outbreak of NDM-5-producing Klebsiella pneumoniae ST307: an emerging high-risk antimicrobial resistance clone in Shanghai, China

The high-risk clone Klebsiella pneumoniae ST307, associated with various carbapenem resistance genes, exhibits a global distribution and prevalence. However, in China, it has remained sporadic and has rarely been detected. In this study, we reported an outbreak caused by nine ST307 CRKP isolates harboring blaNDM-5 in Shanghai, China, in 2022. We employed antimicrobial susceptibility testing, conjugation assay, whole-genome sequencing (WGS) and comparative genomics, phylogenetic analysis, and fitness and virulence comparison to further characterize the isolates causing the outbreak. Besides blaNDM-5, these nine isolates co-carried blaCTX-M-15 and blaDHA-1, exhibiting nearly identical resistance profiles with high-level resistance to carbapenems and ceftazidime/avibactam, while showing susceptibility to colistin and tigecycline. blaNDM-5 was located on an IncX3 plasmid of 45,403 bp with a high frequency of conjugative ability. Phylogenetic and single-nucleotide polymorphism (SNP) analysis indicated the nature of clonal transmission with a maximum of five SNPs between these nine isolates, and they were closely related to strains obtained from the United States. ST307 isolates in our study showed a relatively lower virulence but higher growth rates and certain adaptability compared with ST11 isolates. Clinical investigation revealed that shared nursing staff in a mixed emergency intensive care unit ward and doctors' movement between wards might be responsible for the outbreak. The nonexistence before and sudden emergence of ST307 suggested that the currently circulating ST307 clone was a newly introduced superbug in our hospital. In conclusion, we revealed that blaNDM-5-producing ST307 CRKP isolates, a globally significant high-risk clone, are spreading in China, posing a substantial threat to public health.IMPORTANCEThe high-risk clone ST307, associated with various carbapenemases, including KPC, NDM, and OXA, has a global distribution. However, it is rarely reported in China, let alone causing outbreaks. Here, we found an outbreak caused by the clonal transmission of nine ST307 CRKP isolates. Clinical investigation revealed that shared nurses in a mixed emergency intensive care unit ward and doctors' movement between wards might be responsible for the outbreak. In our study, the nine NDM-5-producing ST307 isolates exhibited high-level resistance to carbapenems and ceftazidime-avibactam, high conjugative ability to Escherichia coli J53, and certain adaptability to environment, phylogenetically closet to the United States. All these features make ST307 clone the next successful clone comparable to ST11 clone in China. Therefore, it is imperative for us to vigilantly monitor the prevalence of carbapenem-resistant Klebsiella pneumoniae and promptly implement measures to control the spread of K. pneumoniae ST307 in China.

Evolution of ceftazidime-avibactam and cefiderocol resistance in ST131-H30R1-Escherichia coli isolates with KPC-3 mutants and application of FTIR biotyping

Ceftazidime-avibactam and cefiderocol represent two of the few alternatives for infections by KPC-producing Enterobacterales. We reported the emergence of resistance to both ceftazidime-avibactam and cefiderocol in a KPC-producing ST131-Escherichia coli (KPC-ST131-Ec) clinical isolate. Antimicrobial susceptibility testing, Fourier-transform infrared (FTIR) spectroscopy, whole-genome sequencing, and cloning experiments were performed. A KPC-49-Ec isolate resistant to ceftazidime-avibactam (MICCZA > 16/4 mg/L) and susceptible to cefiderocol (MICFDC: 2 mg/L) was recovered in a blood sample from an oncologic patient hospitalized in the medical ICU (June 2019) during ceftazidime-avibactam treatment. After 44 days, a KPC-31-Ec resistant to both ceftazidime-avibactam and cefiderocol (MICCZA > 16/4 mg/L, MICFDC: 8 mg/L) was found in a rectal sample during a second cycle of ceftazidime-avibactam treatment. Both KPC-49 (R163S) and KPC-31 (D179Y) were detected in the epidemic ST131-H30R1-Ec high-risk clone and showed a phenotype resembling that of ESBL producers. FTIR spectroscopy managed to differentiate cefiderocol-susceptible and resistant ST131-Ec isolates, and these from others belonging to different clones. After cloning and transformation experiments, KPC-49 and KPC-31 were responsible for ceftazidime-avibactam resistance (MICCZA > 16/4 mg/L) and decreased carbapenem MICs (MICMER ≤ 0.12 mg/L, MICIMI ≤ 1 mg/L). KPC-31 was also shown to be associated with increased MICs of cefiderocol (twofold and threefold dilutions over KPC-3 and KPC-49, respectively). However, mutations in proteins participating in outer membrane stability and integrity, such as TolR, could have a more relevant role in cefiderocol resistance. The effects of ceftazidime-avibactam and cefiderocol co-resistance in clinical isolates of Enterobacterales producing KPC mutants make their identification challenging for clinical laboratories.IMPORTANCEThroughout four admissions in our hospital of a single patient, different KPC-3 variants (KPC-3, KPC-49, and KPC-31) were found in surveillance and clinical ST131-Escherichia coli isolates, after prolonged therapies with meropenem and ceftazidime-avibactam. Different patterns of resistance to cefiderocol and ceftazidime-avibactam emerged, accompanied by restored carbapenem susceptibility. The inability to detect these variants with some phenotypic methods, especially KPC-31 by immunochromatography, and the expression of a phenotype similar to that of ESBL producers, posed challenge to identify these variants in the clinical microbiology laboratory. Molecular methods and whole-genome sequencing are necessary and new techniques able to cluster or differentiate related isolates could also be helpful; this is the case of Fourier-transform infrared spectroscopy, which managed in our study to discriminate isolates by cefiderocol susceptibility within ST131, and those from the non-ST131 ones.

A novel KPC-166 in ceftazidime/avibactam resistant ST307 Klebsiella pneumoniae causing an outbreak in intensive care COVID Unit, Italy

INTRODUCTION

Aim of the study was the molecular characterization of 21 ceftazidime/avibactam resistant (CZA-R) Klebsiella pneumoniae strains, collected in the period October 2021-March 2022 from an Intensive Care COVID Unit in a Northern Italian Hospital.

METHODS

After growth on selective/chromogenic culture media and susceptibility tests assessment, resistance genes content was ascertained for all the isolates by the HybriSpot 12 multiplexing, PCR and Whole-Genome Sequencing (WGS). Clonality was assessed by PFGE and MLST according to the Pasteur scheme. A SNPs-based phylogenetic tree was obtained comparing representative isolates and global genomes. The blaKPC gene horizontal transmission was evaluated by conjugation experiments. blaKPC-166 was cloned in a pCR2.1 vector and transformed in chemically competent TOP10 cells.

RESULTS

Sixteen inpatients resulted positive for colonization and/or infection by KPC-producing K. pneumoniae (KPC-Kp) strains. The 21 CZA-R KPC-Kp isolates obtained showed MDR phenotype; susceptibility to meropenem was always retained. All the CZA-R KPC-Kp presented a novel blaKPC variant, named blaKPC-166, showing a single nucleotide substitution (T811C) compared to the blaKPC-94; but related to blaKPC-2.

TWO DIFFERENT PULSOTYPES WERE DETECTED

A in 18/21 and B in 1/21 cases, two strains from the same patient being untypable by PFGE. Interestingly, the outbreak was sustained by the high-risk clone ST307, although the ST22, ST6342, ST6418 and ST6811 have also been identified and associated to KPC-166. Worryingly, blaKPC-166 could be transferred horizontally and, after cloning, it conferred resistance to CZA.

DISCUSSION

This novel variant confers CZA-resistance and carbapenems susceptibility restoration. As KPC-166 was found expressed by multiple Kp clones, greater efforts should be made to prevent the further dissemination of such strains in Italian clinical settings.

Plant-Origin Components: New Players to Combat Antibiotic Resistance in Klebsiella pneumoniae

Klebsiella pneumoniae (Kpn) is an opportunistic pathogen that causes intrahospital complications such as pneumonia, liver abscesses, soft tissue infections, urinary infections, bacteraemia, and, in some cases, death. Since this bacterium has a higher frequency than other Gram-negative pathogens, it has become an important pathogen to the health sector. The adaptative genome of Kpn likely facilitates increased survival of the pathogen in diverse situations. Therefore, several studies have been focused on developing new molecules, synergistic formulations, and biomaterials that make it possible to combat and control infections with and dispersion of this pathogen. Note that the uncontrolled antibiotic administration that occurred during the pandemic led to the emergence of new multidrug-resistant strains, and scientists were challenged to overcome them. This review aims to compile the latest information on Kpn that generates intrahospital infections, specifically their pathogenicity-associated factors. Furthermore, it explains the natural-product-based treatments (extracts and essential oils) developed for Kpn infection and dispersion control.

Prevalence and mortality of ceftazidime/avibactam-resistant KPC-producing Klebsiella pneumoniae bloodstream infections (2018-2022)

INTRODUCTION

Ceftazidime/avibactam-resistance in Klebsiella pneumoniae carbapenemase-producing Klebsiella pneumoniae (KPC-Kp) is a topic of great interest for epidemiological, diagnostic, and therapeutical reasons. However, data on its prevalence and burden on mortality in patients with bloodstream infection (BSI) are lacking. This study was aimed at identifying risk factors for mortality in patients suffering from ceftazidime/avibactam-resistant KPC-Kp BSI.

METHODS

An observational retrospective study (January 2018-December 2022) was conducted at a tertiary hospital including all consecutive hospitalized adult patients with a ceftazidime/avibactam-resistant KPC-Kp BSI. Data on baseline clinical features, management, and admission outcomes were analyzed.

RESULTS

Over the study period, among all the KPC-Kp BSI events recorded, 38 (10.5%) were caused by ceftazidime/avibactam-resistant KPC-Kp strains, 37 events being finally included. The ceftazidime/avibactam-resistant KPC-Kp strains revealed susceptibility restoration to at least one carbapenem in more than 60% of cases. In-hospital and 30-day all-cause mortality rates were 22% and 16.2%, respectively. Non-survivors suffered from more baseline comorbidities and experienced a more severe ceftazidime/avibactam-resistant KPC-Kp BSI presentation (i.e., both the Pitt Bacteremia and INCREMENT-CPE scores were significantly higher). Presenting with a higher Charlson Comorbidity Index, chronic kidney disease-KDIGO stage 3A or worse-having recently gone through renal replacement therapy, having suffered from an acute kidney injury following the ceftazidime/avibactam-resistant KPC-Kp BSI, and being admitted for cardiac surgery were the strongest predictors of mortality.

CONCLUSION

Ceftazidime/avibactam resistance in KPC-Kp BSI easily emerged in our highly KPC-Kp endemic area with remarkable mortality rates. Our findings might provide physicians possibly actionable information when managing patients with a ceftazidime/avibactam-resistant KPC-Kp BSI.

Klebsiella pneumoniae carbapenemase variants: the new threat to global public health

Klebsiella pneumoniae carbapenemase (KPC) variants, which refer to the substitution, insertion, or deletion of amino acid sequence compared to wild blaKPC type, have reduced utility of ceftazidime-avibactam (CZA), a pioneer antimicrobial agent in treating carbapenem-resistant Enterobacterales infections. So far, more than 150 blaKPC variants have been reported worldwide, and most of the new variants were discovered in the past 3 years, which calls for public alarm. The KPC variant protein enhances the affinity to ceftazidime and weakens the affinity to avibactam by changing the KPC structure, thereby mediating bacterial resistance to CZA. At present, there are still no guidelines or expert consensus to make recommendations for the diagnosis and treatment of infections caused by KPC variants. In addition, meropenem-vaborbactam, imipenem-relebactam, and other new β-lactam-β-lactamase inhibitor combinations have little discussion on KPC variants. This review aims to discuss the clinical characteristics, risk factors, epidemiological characteristics, antimicrobial susceptibility profiles, methods for detecting blaKPC variants, treatment options, and future perspectives of blaKPC variants worldwide to alert this new great public health threat.

The CARBA-MAP study: national mapping of carbapenemases in Spain (2014-2018)

Introduction

Infections caused by carbapenem-resistant Enterobacterales (CRE) and carbapenem-resistant Pseudomonas aeruginosa, including isolates producing acquired carbapenemases, constitute a prevalent health problem worldwide. The primary objective of this study was to determine the distribution of the different carbapenemases among carbapenemase-producing Enterobacterales (CPE, specifically Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae complex, and Klebsiella aerogenes) and carbapenemase-producing P. aeruginosa (CPPA) in Spain from January 2014 to December 2018.

Methods

A national, retrospective, cross-sectional multicenter study was performed. The study included the first isolate per patient and year obtained from clinical samples and obtained for diagnosis of infection in hospitalized patients. A structured questionnaire was completed by the participating centers using the REDCap platform, and results were analyzed using IBM SPSS Statistics 29.0.0.

Results

A total of 2,704 carbapenemase-producing microorganisms were included, for which the type of carbapenemase was determined in 2692 cases: 2280 CPE (84.7%) and 412 CPPA (15.3%), most often using molecular methods and immunochromatographic assays. Globally, the most frequent types of carbapenemase in Enterobacterales and P. aeruginosa were OXA-48-like, alone or in combination with other enzymes (1,523 cases, 66.8%) and VIM (365 cases, 88.6%), respectively. Among Enterobacterales, carbapenemase-producing K. pneumoniae was reported in 1821 cases (79.9%), followed by E. cloacae complex in 334 cases (14.6%). In Enterobacterales, KPC is mainly present in the South and South-East regions of Spain and OXA-48-like in the rest of the country. Regarding P. aeruginosa, VIM is widely distributed all over the country. Globally, an increasing percentage of OXA-48-like enzymes was observed from 2014 to 2017. KPC enzymes were more frequent in 2017-2018 compared to 2014-2016.

Discussion

Data from this study help to understand the situation and evolution of the main species of CPE and CPPA in Spain, with practical implications for control and optimal treatment of infections caused by these multi-drug resistant organisms.

Whole-Genome Sequencing and Molecular Analysis of Ceftazidime-Avibactam-Resistant KPC-Producing Klebsiella pneumoniae from Intestinal Colonization in Elderly Patients

Ceftazidime-avibactam (CAZ-AVI) is an active antibiotic combination of a β-lactam-β-lactamase inhibitor against carbapenemase-producing Enterobacterales. Reports of resistance to CAZ-AVI other than metallo-β-lactamases have increased in recent years. The aim of this study was to analyze KPC-Klebsiella pneumoniae (KP) isolates resistant to CAZ-AVI from the intestinal carriage of hospitalized elderly patients in Italy, in February 2018-January 2020. Characterization of CAZ-AVI-resistant KP isolates, including MLST, resistome, virulome and plasmid content, was performed by WGS analysis. Out of six CAZ-AVI-resistant KP isolates, three belonged to ST101 and three to ST512; two isolates produced KPC-3 (both ST512), four had mutated KPC-3 (KPC-31, in ST101 and ST512, and KPC-46, both ST101). All CAZ-AVI-resistant KP isolates were multidrug-resistant and carried several resistance genes. The yersiniabactin ybt9 gene cluster was present in all ST101 isolates, while, in ST512 isolates, no virulence genes were detected. Several plasmids were detected: IncF was present in all isolates, as well as IncR and Col440 in ST101 and IncX3 in ST512 isolates. In conclusion, it is important to monitor the circulation of K. pneumoniae resistant to CAZ-AVI to prevent the spread of clones causing difficult-to-treat infections. The presence of mutated KPC-3 in high-risk K. pneumoniae clones resistant to CAZ-AVI in hospitalized patients deserves attention.

Resistance to Ceftazidime/Avibactam in Klebsiella pneumoniae KPC-Producing Isolates: A Real-Life Observational Study

Background: Ceftazidime/avibactam (CAZ-AVI) resistance amongst Enterobacterales is worryingly increasing worldwide. Objectives: The aim of this study was to collect and describe real-life data on CAZ-AVI-resistant Klebsiella pneumoniae (KP) isolates in our University Hospital, with the ultimate goal of evaluating possible risk factors related to the acquisition of resistance. Methods: This is a retrospective observational study, including unique Klebsiella pneumoniae (KP) isolates resistant to CAZ-AVI (CAZ-AVI-R) and producing only KPC, collected from July 2019 to August 2021 at Policlinico Tor Vergata, Rome, Italy. The pathogen's list was obtained from the microbiology laboratory; clinical charts of the corresponding patients were reviewed to collect demographic and clinical data. Subjects treated as outpatients or hospitalized for <48 h were excluded. Patients were then divided into two groups: S group, if they had a prior isolate of CAZ-AVI-susceptible KP-KPC, and R group, if the first documented isolate of KP-KPC was resistant to CAZ-AVI. Results: Forty-six unique isolates corresponding to 46 patients were included in the study. The majority of patients (60.9%) were hospitalized in an intensive care unit, 32.6% in internal medicine wards and 6.5% in surgical wards. A total of 15 (32.6%) isolates were collected from rectal swabs, representing a colonization. Amongst clinically relevant infections, pneumonia and urinary tract infections were the most commonly found (5/46, 10.9% each). Half of the patients received CAZ-AVI prior to isolation of the KP-KPC CAZ-AVI-R (23/46). This percentage was significantly higher in patients in the S group compared to patients in the R group (69.3% S group vs. 25% R group, p = 0.003). No differences between the two groups were documented in the use of renal replacement therapy or in the infection site. The clinically relevant CAZ-AVI-R KP infections (22/46, 47.8%) were all treated with a combination therapy, 65% including colistin and 55% including CAZ-AVI, with an overall clinical success of 38.1%. Conclusions: Prior use of CAZ-AVI was associated with the emergence of drug resistance.

Rapid diagnostics and ceftazidime/avibactam for KPC-producing Klebsiella pneumoniae bloodstream infections: impact on mortality and role of combination therapy

This study was aimed at investigating risk factors for mortality in patients suffering from KPC-producing Klebsiella pneumoniae (KPC-Kp) bloodstream infections (BSIs), evaluating the impact of rapid diagnostics and ceftazidime/avibactam use. This observational retrospective study (January 2017-May 2021) included all patients with a KPC-Kp BSI. Uni-multivariable analyses were carried out to evaluate the effect of clinical variables on both in-hospital death (IHD) and 30-day all-cause mortality, and the role of the combination of ceftazidime/avibactam plus polymyxin. One hundred and ninety-six patients met the study's inclusion criteria. Older age, having undergone renal replacement therapy during the 30 days preceding the KPC-Kp BSI onset, having an INCREMENT-CPE score ≥ 8, and having suffered from a superimposed and/or following KPC-Kp BSI treatment candidemia were found to be the main factors associated with both mortality rates. Among protective factors, the centrality of ceftazidime/avibactam in monotherapy (IHD: OR: 0.34; CI 95%: 0.11-1.00-30-day all-cause mortality: OR: 0.18; CI 95%: 0.04-0.77) or combination (IHD: OR: 0.51; CI 95%: 0.22-1.19-30-day all-cause mortality: OR: 0.62; CI 95%: 0.21-1.84) emerged and became even more evident once the effect of ceftazidime/avibactam plus polymyxin was removed. Rapid diagnostics may be useful to adopt more effective strategies for the treatment of KPC-Kp BSI patients and implement infection control measures, even if not associated with higher patient survival. Ceftazidime/avibactam, even when used alone, represents an important option against KPC-Kp, while combined use with polymyxin might not have altered its efficacy. Patient comorbidities, severity of BSI, and complications such as candidemia were confirmed to have a significant burden on survival.

Antimicrobial resistance in Gram-negative bacilli in Spain: an experts' view

BACKGROUND

Antibiotic resistance in Gram-negative bacilli poses a serious problem for public health. In hospitals, in addition to high mortality rates, the emergence and spread of resistance to practically all antibiotics restricts therapeutic options against serious and frequent infections.

OBJECTIVE

The aim of this work is to present the views of a group of experts on the following aspects regarding resistance to antimicrobial agents in Gram-negative bacilli: 1) the current epidemiology in Spain, 2) how it is related to local clinical practice and 3) new therapies in this area, based on currently available evidence.

METHODS

After reviewing the most noteworthy evidence, the most relevant data on these three aspects were presented at a national meeting to 99 experts in infectious diseases, clinical microbiology, internal medicine, intensive care medicine, anaesthesiology and hospital pharmacy.

RESULTS AND CONCLUSIONS

Subsequent local debates among these experts led to conclusions in this matter, including the opinion that the approval of new antibiotics makes it necessary to train the specialists involved in order to optimise how they use them and improve health outcomes; microbiology laboratories in hospitals must be available throughout a continuous timetable; all antibiotics must be available when needed and it is necessary to learn to use them correctly; and the Antimicrobial Stewardship Programs (ASP) play a key role in quickly allocating the new antibiotics within the guidelines and ensure appropriate use of them.

Current Positioning against Severe Infections Due to Klebsiella pneumoniae in Hospitalized Adults

Infections due to Klebsiella pneumoniae have been increasing in intensive care units (ICUs) in the last decade. Such infections pose a serious problem, especially when antimicrobial resistance is present. We created a task force of experts, including specialists in intensive care medicine, anaesthesia, microbiology and infectious diseases, selected on the basis of their varied experience in the field of nosocomial infections, who conducted a comprehensive review of the recently published literature on the management of carbapenemase-producing Enterobacterales (CPE) infections in the intensive care setting from 2012 to 2022 to summarize the best available treatment. The group established priorities regarding management, based on both the risk of developing infections caused by K. pneumoniae and the risk of poor outcome. Moreover, we reviewed and updated the most important clinical entities and the new antibiotic treatments recently developed. After analysis of the priorities outlined, this group of experts established a series of recommendations and designed a management algorithm.

Increased blaKPC Copy Number and OmpK35 and OmpK36 Porins Disruption Mediated Resistance to Imipenem/Relebactam and Meropenem/Vaborbactam in a KPC-Producing Klebsiella pneumoniae Clinical Isolate

Herein, we report the in vivo evolution of imipenem/relebactam-resistance in KPC-producing K. pneumoniae (KPC-Kp) isolated from a critically-ill patient treated with multiple combination therapies based on ceftazidime-avibactam or meropenem-vaborbactam. Imipenem/relebactam-resistance was associated to meropenem-vaborbactam cross-resistance and was due to truncated OmpK35 and OmpK36 porins and increased copy of blaKPC copy number. Genome analysis demonstrated that imipenem/relebactam-resistant KPC-Kp harbored a second copy of blaKPC-carrying Tn4401 in a ColRNAI plasmid as a consequence of a transposition event.

Risk factors for and clinical outcomes of ceftazidime-avibactam-resistant carbapenem-resistant Klebsiella pneumoniae nosocomial infections: a single-center retrospective study

PURPOSE

The emergence of ceftazidime-avibactam (CZA) resistance in carbapenem-resistant Klebsiella pneumoniae (CRKP) has been increasingly reported in recent years. We aimed to identify the risk factors of CZA-resistant CRKP infection and assess clinical outcomes of the patients.

METHODS

The study retrospectively analyzed the clinical and microbiological data of patients with CRKP infection to identify risk factors, clinical features, and outcomes using multivariate logistic regression analysis.

RESULTS

A total of 103 patients with CRKP infection were enrolled in this study. Multivariate analysis showed previous renal replacement therapy (OR 3.966, 95% CI 1.301-12.090, P = 0.015) was an independent risk factor for CZA-resistant CRKP infection. The 28-day mortality was higher in patients infected with CZA-resistant CRKP (27.9%) than those with CZA-susceptible CRKP (7.1%) (P = 0.009). CZA-resistant CRKP infection (OR 20.308, 95% CI 1.461-282.293, P = 0.025), and mechanical ventilation (OR 14.950, 95% CI 1.034-216.212, P = 0.047) were independent predictors for 28-day mortality in patients with CRKP infection. Lower level of platelet count (OR 0.987, 95% CI 0.975-0.999, P = 0.032) on the day of CRKP infection onset was related to 28-day mortality. Kaplan-Meier curves showed that the CZA-resistant CRKP group had a shorter survival time than the CZA-susceptible CRKP group.

CONCLUSION

The prevalence and mortality of CZA-resistant CRKP are still increasing. Strengthening the hospital infection control of renal replacement therapy and mechanical ventilation may help to prevent CZA-resistant CRKP.