Carbapenem-resistant K. Pneumoniae Research Articles

Clonal transmission of blaIMP-4-carrying ST196 Klebsiella pneumoniae isolates mediated by IncN plasmid in China

ObjectivesTo investigate the clinical and molecular epidemiological characteristics of blaIMP-4-carrying Klebsiella pneumoniae in a tertiary hospital in China. Methods10 Carbapenem Resistant K. pneumoniae (CRKP) isolates with blaIMP-4 gene were collected. Molecular characteristics were analyzed using whole-genome sequencing. Plasmid conjugation experiment was used to analyze the conjugation of plasmids. We compared and analyzed K. pneumoniae carrying blaIMP-4 on NCBI with the strains in this study. ResultsAll 10 CRKP isolates with blaIMP-4 were collected from 10 adult patients in the respiratory intensive care unit. These strains were only sensitive to polymyxins and tigecycline due to simultaneously carrying multiple resistance genes, such as blaOKP-A-5, fosA, oqxA and oqxB. Notably, R29 harbored two carbapenemase genes (blaNDM-1 and blaIMP-4). These strains had similar drug-resistant phenotypes and drug-resistant genes, all belonging to ST196. Additionally, the patients had spatiotemporal intersection during hospitalization, suggesting that these strains had clonal transmission, but they belonged to different clonal clusters from the blaIMP-4-positive K. pneumoniae currently published on NCBI. Among the 10 strains, blaIMP-4 was located on the IncN plasmid, and 6 strains had successfully transferred the plasmid to the recipient strain EC600 through plasmid conjugation. ConclusionsThe blaIMP-4-positive ST196 CRKP had clonal distribution in the respiratory ICU, which was mediated by IncN plasmid. Consequently, there should be increased monitoring of carbapenem-resistant strains in clinical settings to prevent and control of its transmission.

Respiratory carriage of hypervirulent Klebsiella pneumoniae by indigenous populations of Malaysia

Klebsiella pneumoniae is a Gram-negative Enterobacteriaceae that is classified by the World Health Organisation (WHO) as a Priority One ESKAPE pathogen. South and Southeast Asian countries are regions where both healthcare associated infections (HAI) and community acquired infections (CAI) due to extended-spectrum β-lactamase (ESBL)-producing and carbapenem-resistant K. pneumoniae (CRKp) are of concern. As K. pneumoniae can also exist as a harmless commensal, the spread of resistance genotypes requires epidemiological vigilance. However there has been no significant study of carriage isolates from healthy individuals, particularly in Southeast Asia, and specially Malaysia. Here we describe the genomic analysis of respiratory isolates of K. pneumoniae obtained from Orang Ulu and Orang Asli communities in Malaysian Borneo and Peninsular Malaysia respectively. The majority of isolates were K. pneumoniae species complex (KpSC) 1 K. pneumoniae (n = 53, 89.8%). Four Klebsiella variicola subsp. variicola (KpSC3) and two Klebsiella quasipneumoniae subsp. similipneumoniae (KpSC4) were also found. It was discovered that 30.2% (n = 16) of the KpSC1 isolates were ST23, 11.3% (n = 6) were of ST65, 7.5% (n = 4) were ST13, and 13.2% (n = 7) were ST86. Only eight of the KpSC1 isolates encoded ESBL, but importantly not carbapenemase. Thirteen of the KpSC1 isolates carried yersiniabactin, colibactin and aerobactin, all of which harboured the rmpADC locus and are therefore characterised as hypervirulent. Co-carriage of multiple strains was minimal. In conclusion, most isolates were KpSC1, ST23, one of the most common sequence types and previously found in cases of K. pneumoniae infection. A proportion were hypervirulent (hvKp) however antibiotic resistance was low.

Hybrid Sequencing-Based Genomic Analysis of Klebsiella pneumoniae from Urinary Tract Infections Among Inpatients at a Tertiary Hospital in Beijing.

Urinary tract infection (UTI) associated with Klebsiella pneumoniae poses a serious threat for inpatients. This study aimed to describe the genomic characteristics of K. pneumoniae causing UTI in a tertiary-care hospital in Beijing, China. A total of 20 K. pneumoniae strains collected from 2020 to 2021 were performed whole-genome sequencing. The Antibiotic susceptibility of 19 common antimicrobial agents was tested against all strains. The multi-locus sequence types (MLSTs) and serotypes were determined from the WGS data. De novo assemblies were used to identify resistance and virulence genes. The presence and characteristics of the plasmids were detected using hybrid assembly of long and short-read data. These K. pneumoniae strains were clustered into nine sequence types (STs) and twelve K-serotypes. All the carbapenem-resistant K. pneumoniae (CRKP) strains acquired carbapenemase blaKPC-2 (n=7). Two CRKP strains exhibited increased resistance to Polymyxin B with MIC ≥ 4 mg/L due to insertion of an IS5-like sequence in the mgrB gene, and they were also involved in a transmission event in Intensive Care Unit. Long-read assemblies identified many plasmids co-carrying multiple replicons. Acquisition of a new IncM2_1 type blaCTX-M-3 positive plasmid was observed after transfer from ICU to neurovascular surgery by comparing the two strains collected from the same patient. K. pneumoniae is a significant pathogen responsible for urinary tract infections. The ST11-KL47 strain, prevalent at our hospital, exhibits a combination of high drug resistance and hypervirulence. It is imperative to enhance ongoing genomic surveillance of urinary tract infection-causing pathogens.

KPC-2 and VIM-1 producing Klebsiella pneumoniae ST39 high-risk clone isolated from aclinical sample in Volos, Greece.

Klebsiella pneumoniae is a major human pathogen, because it causes both community- and hospital-acquired infections. Several multidrug-resistant high-risk clones of K. pneumoniae have been reported worldwide, and these are responsible for high numbers of difficult-to-treat infections. In Greece, a K.pneumoniae ST39 high-risk clone was detected in 2019 in a survey of carbapenem- and/or colistin-resistant Enterobacteriacae. The present study included nine carbapenem-resistant K. pneumoniae (CRKP) isolates collected during a retrospective analysis from October 2020 to December 2020. They were isolated from nine different patients hospitalized in the intensive care unit (ICU) of a hospital in Volos, Greece, and they were selected for analysis due to their phenotypic profile. In this study, we analyzed A165 strain K. pneumoniae ST39 isolated from a blood culture in November 2020. Whole-genome sequencing (WGS) was performed using Ion Torrent Platform, and resistance genes, virulence determinants, capsular types, insertion sequences, phage regions, and clustered regularly interspaced palindromic repeats (CRISPR) regions were detected by bioinformatic analysis. The molecular characterizationrevealed antimicrobial resistance genes, including sul2 for sulfamethoxazole; dfrA1 fortrimethoprim; blaVIM-1 and blaKPC-2 for carbapenems; aac(6')-II for aminoglycosides; fosA forfosfomycin and aad1 for streptomycin, blaSHV-40, blaSHV-85, blaSHV-79, blaSHV-56, and blaSHV-89 forbeta-lactams. Point mutations were identified in ompK36, and ompK37 and in acrR, gyrA, parC. Several replicons were found, including CoIRNA, IncC, IncFIB(K), IncFIB(pQiL), and IncFII(K). Thecapsular typing revealed that the strain was KL23, O2afg. The genome sequence of A165 was submitted to NCBI under PRJNA1074377 and have been assigned to Genbank accession number JAZIBV000000000.

Phenotypic, molecular, and in silico characterization of coumarin as carbapenemase inhibitor to fight carbapenem-resistant Klebsiella pneumoniae

BackgroundCarbapenems represent the first line treatment of serious infections caused by drug-resistant Klebsiella pneumoniae. Carbapenem-resistant K. pneumoniae (CRKP) is one of the urgent threats to human health worldwide. The current study aims to evaluate the carbapenemase inhibitory potential of coumarin and to test its ability to restore meropenem activity against CRKP. Disk diffusion method was used to test the antimicrobial susceptibility of K. pneumoniae clinical isolates to various antibiotics. Carbapenemase genes (NDM-1, VIM-2, and OXA-9) were detected using PCR. The effect of sub-MIC of coumarin on CRKP isolates was performed using combined disk assay, enzyme inhibition assay, and checkerboard assay. In addition, qRT-PCR was used to estimate the coumarin effect on expression of carbapenemase genes. Molecular docking was used to confirm the interaction between coumarin and binding sites within three carbapenemases.ResultsK. pneumoniae clinical isolates were found to be multi-drug resistant and showed high resistance to meropenem. All bacterial isolates harbor at least one carbapenemase-encoding gene. Coumarin significantly inhibited carbapenemases in the crude periplasmic extract of CRKP. The checkerboard assay indicated that coumarin-meropenem combination was synergistic exhibiting a fractional inhibitory concentration index ≤ 0.5. In addition, qRT-PCR results revealed that coumarin significantly decreased carbapenemase-genes expression. Molecular docking revealed that the binding energies of coumarin to NDM1, VIM-2, OXA-48 and OXA-9 showed a free binding energy of -7.8757, -7.1532, -6.2064 and − 7.4331 Kcal/mol, respectively.ConclusionCoumarin rendered CRKP sensitive to meropenem as evidenced by its inhibitory action on hydrolytic activity and expression of carbapenemases. The current findings suggest that coumarin could be a possible solution to overcome carbapenems resistance in CRKP.

Genomic insights and antimicrobial resistance profiles of CRKP and non-CRKP isolates in a Beijing geriatric medical center: emphasizing the blaKPC-2 carrying high-risk clones and their spread.

The escalating resistance of Klebsiella pneumoniae, a prevalent pathogen in healthcare settings, especially its carbapenem-resistant K. pneumoniae (CRKP), to a wide array of antibiotics, notably β-lactams, constitutes a formidable challenge for healthcare and global public health management. This research compared the resistance phenotypes and genomic profiles of CRKP and Non-CRKP isolates in a Beijing hospital, focusing on high-risk blaKPC-2 gene-bearing CRKP clones and the structure of mobile genetic elements facilitating their spread across hospital departments. Forty K. pneumoniae isolates were collected from various departments of the hospital and subjected to antimicrobial susceptibility testing and whole-genome sequencing to analyze their resistance phenotypes and genomic features. The study revealed that among the 31 CRKP isolates, ST11 is the most common sequence type, with K47 and OL101 being the dominant capsule types, primarily observed in the respiratory department. In terms of antimicrobial susceptibility: 87.5% of the isolates exhibited multidrug resistance (MDR), with a high resistance rate of 30% against tigecycline. All CRKP isolates demonstrated resistance to multiple drug classes (≥5 CLSI classes). Non-CRKP isolates also showed high resistance rates to minocycline and doxycycline (77.8%). the ST11-KL47-OL101 type emerged as the predominant clone among the CRKP isolates carrying the blaKPC-2 gene. This dominance appears to be mediated by the pKpnR03_2 plasmid, which harbors not only blaKPC-2 and rmtb but also gene clusters pertinent to iron transport and arsenic resistance. These isolates, clustering in the C3 clade of the phylogenetic tree, exhibited minor genetic variations and close evolutionary relationships, suggesting a plasmid-driven spread across various hospital departments. In summary, our study highlights the extensive spread of antibiotic-resistant K. pneumoniae across various departments in our hospital, with a particular emphasis on the dominant clonal proliferation of the ST11-KL47-OL101 CRKP strain. This finding underscores the significant role of plasmid-mediated gene transfer in the evolution and dissemination of resistant strains within hospital environments. The study emphasizes the necessity for ongoing surveillance of antibiotic resistance and genomic analysis in hospital settings to effectively monitor and manage these challenges.

Clinical use of tigecycline may contribute to the widespread dissemination of carbapenem-resistant hypervirulent Klebsiella pneumoniae strains

ABSTRACT The emergence of carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) poses grave threats to human health. These strains increased dramatically in clinical settings in China in the past few years but not in other parts of the world. Four isogenic K. pneumoniae strains, including classical K. pneumoniae, carbapenem-resistant K. pneumoniae (CRKP), hypervirulent K. pneumoniae (hvKP) and CR-hvKP, were created and subjected to phenotypic characterization, competition assays, mouse sepsis model and rat colonization tests to investigate the mechanisms underlying the widespread nature of CR-hvKP in China. Acquisition of virulence plasmid led to reduced fitness and abolishment of colonization in the gastrointestinal tract, which may explain why hvKP is not clinically prevalent after its emergence for a long time. However, tigecycline treatment facilitated the colonization of hvKP and CR-hvKP and reduced the population of Lactobacillus spp. in animal gut microbiome. Feeding with Lactobacillus spp. could significantly reduce the colonization of hvKP and CR-hvKP in the animal gastrointestinal tract. Our data implied that the clinical use of tigecycline to treat carbapenem-resistant K. pneumoniae infections facilitated the high spread of CR-hvKP in clinical settings in China and demonstrated that Lactobacillus spp. was a potential candidate for anticolonization strategy against CR-hvKP.

Characteristics of Klebsiella pneumoniae pyogenic liver abscess from 2010–2021 in a tertiary teaching hospital of South China

Pyogenic liver abscess (PLA) is a severe and potentially fatal infectious disease. Klebsiella pneumoniae (K. pneumoniae) is the predominant pathogen responsible for PLA. This study aims to investigate the clinical characteristics and prognostic factors of K. pneumoniae-induced pyogenic liver abscess (KP-PLA), particularly those caused by carbapenem-resistant K. pneumoniae (CRKP). Analyses were performed on PLA patients from January 2010 to December 2021, to investigate the differences of K. pneumoniae from other etiologically infected PLA patients. Univariate and multivariate logistic regression analyses were used to compare prognostic factors between patients with carbapenem-resistant K. pneumoniae PLA (CRKP-PLA) and patients with carbapenem-sensitive K. pneumoniae PLA. Univariate analysis demonstrated a significant association between KP-PLA and factors including diabetes mellitus (P < 0.001), cholecystitis and cholelithiasis (P = 0.032), single abscess (P = 0.016), and abscesses with a diameter over 50 mm (P = 0.004). The CRKP group exhibited a higher prevalence of therapeutic interventions before K. pneumoniae infection, including abdominal surgery, mechanical ventilation, sputum suction, tracheal cannula, routine drainage of the abdominal cavity, and peripherally inserted central venous catheters (P < 0.05). Multivariate logistic regression analysis revealed that admission to the intensive care unit was an independent risk factor associated with CRKP-PLA (odds ratio 36; 95% confidence interval 1.77-731.56; P = 0.020). The KP-PLA patients were significantly associated with diabetes and were more likely to have single abscesses larger than 50 mm. PLA patients with a history of admission to intensive care unit or invasive therapeutic procedures should be given special consideration if combined with CRKP infection.

Efficacy of the bee-venom antimicrobial peptide Osmin against sensitive and carbapenem-resistant Klebsiella pneumoniae strains

The emergence of multidrug-resistant (MDR) Klebsiella pneumoniae strains causes severe problems in the treatment of bacterial infections owing to limited treatment options. Especially, carbapenem-resistant Klebsiella pneumoniae (CRKP) is rapidly spreading worldwide and is emerging as a new cause of drug-resistant healthcare-associated infections. CRKP also has been announced by the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) as one of the most pressing antibiotic resistance threats. Antimicrobial peptides (AMPs) are drawing considerable attention as ideal antibiotic alternative candidates to combat MDR bacterial infections. In a previous study, Osmin is composed of 17 amino acids and is isolated from solitary bee (Osmia rufa) venom. Herein, we evaluated the potential of Osmin to be used against drug-resistant K. pneumoniae as an alternative to conventional antibiotics. Osmin exhibited significant antimicrobial and anti-biofilm activity and lower toxicity than melittin, a well-known bee venom peptide. Additionally, we confirmed that it possesses a bactericidal mechanism that rapidly destroys bacterial membranes. Osmin was relatively more stable than melittin under the influence of various environmental factors and unlike conventional antibiotics, it exhibited a low bacterial resistance risk. During in vivo tests, Osmin reduced bacterial growth and the expression of pro-inflammatory cytokines and fibrosis-related genes in mice with CRKP-induced sepsis. Overall, our results indicate a high potential for Osmin to be used as a valuable therapeutic agent against drug-resistant K. pneumoniae infections.

Metagenomics next-generation sequencing (mNGS) reveals emerging infection induced by Klebsiella pneumoniaeniae

ObjectivesThe increasing emergence of hypervirulent Klebsiella pneumoniae (hv-Kp) and carbapenem-resistant K. pneumoniae (CR-Kp) is a serious and substantial public health problem. The use of the last resort antimicrobials, tigecycline and polymyxin to combat infections is complicated by the expanding repertoire of newly-identified CR-hvKp. The transmission and co-occurrence of the corresponding antimicrobial resistance and virulence determinants are largely unknown. The aim of this study was to investigate the dissemination and dynamics of CR-Kp and its antibiotic resistance in a hospitalised patient. MethodsMetagenomic next-generation sequencing (mNGS) was conducted for different specimens collected from an elderly male hospitalised patient. CR-Kp strains were examined using antibiotic susceptibility and string testing. Antimicrobial and virulence genes were annotated using whole-genome sequencing (WGS). ResultsA clinical case of a patient infected with a variety of CR-Kp isolates was reported. The co-occurrence of KPC-2 and NDM-1 in the patient was revealed. The CR-Kp isolates, such as BALF2, and Sputum T1 and T3, were classified into ST11 and ST147, respectively. The genetic signature (iuc operon) of hypervirulence was identified in strain T1, although string testing indicated its intermediate virulence. ConclusionsIn this study, multiple infections of CR-Kp isolates were revealed by mNGS, and their dissemination was attributed to plasmid variations, mgrB inactivation and integrative conjugative elements (ICEs). Furthermore, the finding indicated one likely convergence to form CR-hvKp, different from acquisition of carbapenem-resistance determinants in hvKp. A combination of mNGS and WGS is beneficial for clinical diagnosis and anti-infection therapy, and facilitates a better understanding of genetic variants conferring antimicrobial and virulence properties.

Molecular Screening of Carbapenem-Resistant K. pneumoniae (CRKP) Clinical Isolates for Concomitant Occurrence of Beta-Lactam Genes (CTX-M, TEM, and SHV) in the Kingdom of Bahrain.

The emergence of extended-spectrum β-lactamase-producing Klebsiella pneumoniae, including CRKP infections, has resulted in significant morbidity and mortality worldwide. We aimed to explore the presence of bla genes (CTX-M, TEM, and SHV) in CRKP isolates. A total of 24 CRKP isolates were randomly selected from the Salmaniya Medical Complex Microbiology Laboratory. These isolates, which were positive for carbapenemases, were further explored for CTX-M, TEM, and SHV genes using PCR. All the CTX-M PCR amplicons were sent for sequencing. To determine genetic relatedness, molecular typing by ERIC-PCR was performed. The bla gene testing demonstrated that a significant proportion of these isolates harbored SHV, CTX-M, and TEM genes (100%, 91.6%, and 45.8%), respectively. Bioinformatic analyses confirmed CTX-M-15 in these isolates. ERIC-PCR analysis showed three clusters demonstrating genetic relatedness. The study findings reveal the concomitant carriage of the SHV and CTX-M-15 and a comparatively lower carriage of TEM genes in CRKP isolates. Our findings highlight the significance of routinely reporting the presence of antibiotic resistance genes along with regular antibiotic sensitivity reports, as this will aid clinicians in prescribing appropriate antibiotics.

Clinical and molecular characteristics of Klebsiella pneumoniae infection in a tertiary general hospital of Wuhan, China

ObjectivesThe aim of this study was to investigate the clinical and molecular characteristics of Klebsiella pneumoniae infection from a tertiary general hospital in Wuhan, China.MethodsFrom December 2019 to August 2022, 311 non-duplicate isolates of K. pneumoniae were collected from a tertiary hospital in Wuhan. These comprised 140 carbapenem-resistant K. pneumoniae (CRKP) isolates and 171 carbapenem-susceptible K. pneumoniae (CSKP) isolates. The clinical characteristics of patients with K. pneumoniae infection were retrospectively collected. Polymerase chain reaction (PCR) assays were used to identify the main carbapenem resistance genes, virulence genes and multi-locus sequence typing (MLST) profiles of the isolates, and the Galleria mellonella infection model was used to determine their virulence phenotypes.ResultsIndependent risk factors for CRKP infection were hypertension, neurological disorders, being admitted to the intensive care unit (ICU) and prior use of antibiotics. Patient with CRKP infection had higher mortality than those with CSKP infection (23.6% vs 14.0%, P < 0.05). One hundred and two sequence types (STs) were identified among the K. pneumoniae isolates, and the most prevalent ST type was ST11 (112/311, 36.0%). All of the ST11 isolates were CRKP. Among the 112 ST11 isolates, 105 (93.8%) harboured the carbapenem resistance gene blaKPC-2 (ST11-KPC-2), and of these isolates, 78 (74.3%, 78/105) contained all of the four virulence genes, namely rmpA, rmpA2, iroN and iucA, suggesting that these genes were widespread among the isolates responsible for K. pneumoniae infections.ConclusionIn this study, ST11-KPC-2 was responsible for most of the K. pneumoniae infection cases. Carbapenem resistance rather than the co-occurrence of the virulence genes rmpA, rmpA2, iroN and iucA was associated with K. pneumoniae infection-related mortality during hospitalisation. Furthermore, a high proportion of ST11-KPC-2 isolates carried all of the four virulence genes.

Risk Factors and Mortality of Elderly Patients with Hospital-Acquired Pneumonia of Carbapenem-Resistant Klebsiella pneumoniae Infection.

Hospital-acquired pneumonia (HAP) caused by carbapenem-resistant K. pneumoniae (CRKP), especially in elderly patients, results in high morbidity and mortality. Studies on risk factors, mortality, and antimicrobial susceptibility of CRKP pulmonary infection among elderly patients are lacking. A retrospective case-control study was conducted from January 2019 to December 2021. The elderly inpatients (≥65 years) who were diagnosed with HAP caused by K. pneumoniae were enrolled. Clinical data were collected. Univariate and multivariate logistic regression analyses were used to identify risk factors. Propensity score matching was used to minimize the effect of potential confounding variables. Kaplan-Meier analysis was used to compare survival. A total of 115 patients with CRKP infection and 78 patients with carbapenem-susceptible K. pneumoniae (CSKP) infection were recruited. There were four independent risk factors for CRKP infection: history of intensive care unit (ICU) stays from hospital admission to positive respiratory specimen culture for K. pneumoniae (odds ratio (OR)=2.530), Charlson comorbidity index score ≥3 (OR = 2.420), prior exposure to carbapenems (OR = 5.280), and prior K. pneumoniae infection or colonization in the preceding 3 years (OR = 18.529). The all-cause 30-day mortality was 22.3%, the mortality of CRKP and CSKP infection was 28.7% and 12.8%, respectively. Independent risk factors for mortality included: older age (OR = 1.107), immunocompromised patients (OR = 8.632), severe pneumonia (OR = 51.244), quick Sepsis-related Organ Failure Assessment (qSOFA) score ≥2 (OR = 6.187), exposure to tigecycline before infection (OR = 24.702), and prolonged ICU stay (OR = 0.987). Thirty-day mortality was significantly lower in patients receiving ceftazidime-avibactam (CAZ-AVI) containing regimens than patients receiving polymyxin B sulfate (PB) containing regimens (P = 0.048). qSOFA score had a good prognostic effect [area under receiver operating characteristic curve (AUROC) of 0.838]. Active screening of CRKP for the high-risk populations, especially elderly patients, is significant for early detection and successful management of CRKP infection.

Acquisition of a novel conjugative multidrug‐resistant hypervirulent plasmid leads to hypervirulence in clinical carbapenem‐resistant Klebsiella pneumoniae strains

AbstractThe co‐occurrence of plasmid‐mediated multidrug resistance and hypervirulence in epidemic carbapenem‐resistant Klebsiella pneumoniae has emerged as a global public health issue. In this study, an ST23 carbapenem‐resistant hypervirulent K. pneumoniae (CR‐HvKP) strain VH1‐2 was identified from cucumber in China and harbored a novel hybrid plasmid pVH1‐2‐VIR. The plasmid pVH1‐2‐VIR carrying both virulence and multidrug‐resistance (MDR) genes was likely generated through the recombination of a virulence plasmid and an IncFIIK conjugative MDR plasmid in clinical ST23 18622 isolated from a sputum sample. The plasmid pVH1‐2‐VIR exhibited the capacity for transfer to the clinical ST11 carbapenem‐resistant K. pneumoniae (CRKP) strain via conjugation assay. Acquisition of pVH1‐2‐VIR plasmid directly converted a CRKP into CR‐HvKP strain characterized by hypermucoviscosity, heightened virulence for Galleria mellonella larvae, and increased colonization ability in the mouse intestine. The emergence of such a hybrid plasmid may expedite the spread of CR‐HvKP strains, posing a significant risk to human health.

Mortality in KPC-producing Klebsiella pneumoniae bloodstream infections: a changing landscape.

To assess the impact of carbapenem resistance on mortality in Klebsiella pneumoniae bloodstream infection (BSI) in the era of novel β-lactam/β-lactamase inhibitor combinations. Retrospective study of patients with K. pneumoniae BSI between January and August 2020 in 16 centres (CARBANEW study within the MULTI-SITA project). Overall, 426 patients were included: 107/426 (25%) had carbapenem-resistant K. pneumoniae (CR-Kp) BSI and 319/426 (75%) had carbapenem-susceptible K. pneumoniae (CS-Kp) BSI. Crude cumulative 30 day mortality was 33.8% and 20.7% in patients with, respectively, CR-Kp BSI and CS-Kp BSI (P = 0.027). Carbapenemase production or carbapenemase-encoding genes were detected in 84/98 tested CR-Kp isolates (85.7%), mainly KPC (78/84; 92.9%). Ceftazidime/avibactam was the most frequently used appropriate therapy for CR-Kp BSI (80/107; 74.7%). In multivariable analyses, variables showing an unfavourable association with mortality after correction for multiple testing were age-adjusted Charlson comorbidity index (HR 1.20; 95% CI 1.10-1.31, P < 0.001) and Pitt score (HR 1.33; 95% CI 1.15-1.55, P < 0.001), but not carbapenem resistance (HR 1.28, 95% CI 0.74-2.22, P = 0.410). In a propensity score-matched analysis, there was no difference in mortality between patients appropriately treated with ceftazidime/avibactam for CR-Kp BSI and patients appropriately treated with other agents (mainly meropenem monotherapy or piperacillin/tazobactam monotherapy) for CS-Kp BSI (HR 1.07; 95% CI 0.50-2.29, P = 0.866). Our results suggest that the increased mortality in CR-Kp BSI compared with CS-Kp BSI is not (or no longer) dependent on the type of therapy in areas where ceftazidime/avibactam-susceptible KPC-producing isolates are the most prevalent type of CR-Kp.

Persistent transmission of carbapenem-resistant, hypervirulent Klebsiella pneumoniae between a hospital and urban aquatic environments

The increasing prevalence of infections caused by carbapenem-resistant hypervirulent Klebsiella pneumoniae strains (CR-hvKP) prompts the question of whether these strains also circulate outside of clinical settings. However, the environmental occurrence and dissemination of CR-hvKP are poorly studied. In the current study, we investigated the epidemiological characteristics, and dissemination dynamics of carbapenem-resistant K. pneumoniae (CRKP) isolated from a hospital, an urban wastewater treatment plant (WWTP), and adjacent rivers in Eastern China during one year of monitoring. A total of 101 CRKP were isolated, 54 were determined to be CR-hvKP harboring pLVPK-like virulence plasmids, which were isolated from the hospital (29 out of 51), WWTP (23 out of 46), and rivers (2 out of 4), respectively. The period with lowest detection rate of CR-hvKP in the WWTP, August, corresponded with the lowest detection rate at the hospital. Comparing the inlet and outlet of the WWTP, no significant reduction of the detection of CR-hvKP and relative abundance of carbapenem resistance genes was observed. The detection rate of CR-hvKP and the relative abundance of carbapenemase genes were significantly higher in the WWTP in colder months compared to warmer months. Clonal dissemination of CR-hvKP clones of ST11-KL64 between the hospital and the aquatic environment, as well as the horizontal spread of IncFII-IncR and IncC plasmids carrying carbapenemase genes, was observed. Furthermore, phylogenetic analysis showed that the ST11-KL64 CR-hvKP strain has spread nationally by interregional transmission. These results indicated transmission of CR-hvKP clones between hospital and urban aquatic environments, prompting the need for improved wastewater disinfection and epidemiological models to predict the public health hazard from prevalence data of CR-hvKP.

The association between ambient temperature and antimicrobial resistance of Klebsiella pneumoniae in China: a difference-in-differences analysis.

Antimicrobial resistance (AMR) of Klebsiella pneumoniae (K. pneumoniae) poses a significant global public health threat and is responsible for a high prevalence of infections and mortality. However, knowledge about how ambient temperature influences the AMR of K. pneumoniae is limited in the context of global warming. AMR data of 31 Chinese provinces was collected from the China Antimicrobial Resistance Surveillance System (CARSS) between 2014 and 2020. Socioeconomic and meteorological data were collected from the China Statistical Yearbook during the same period. A modified difference-in-differences (DID) approach was applied to estimate the association between ambient temperature and third-generation cephalosporin-resistant K. pneumoniae (3GCRKP) and carbapenem-resistant K. pneumoniae (CRKP). Furthermore, moderating effects of socioeconomic factors were also evaluated. Every 1°C increase in annual average temperature was associated with a 4.7% (relative risk (RR):1.047, 95% confidence intervals (CI): 1.031-1.082) increase in the detection rate of 3GCRKP, and a 10.7% (RR:1.107, 95% CI: 1.011-1.211) increase in the detection rate of CRKP. The relationships between ambient temperature and 3GCRKP and CRKP were found to be moderated by socioeconomic status (GDP per capita, income per capita, and consumption per capita; the interaction p-values <0.05), where higher economic status was found to strengthen the effects of temperature on the detection rate of 3GCRKP and weaken the effects on the detection rate of CRKP. Ambient temperature was found to be positively associated with AMR of K. pneumoniae, and this association was moderated by socioeconomic status. Policymakers should consider the impact of global warming and high temperatures on the spread of 3GCRKP and CRKP when developing strategies for the containment of AMR.

Isolation of Hv-CRKP with co-production of three carbapenemases (blaKPC, blaOXA-181 or OXA-232, and blaNDM-1) and a virulence plasmid: a study from a Chinese tertiary hospital.

The worldwide dissemination of K. pneumoniae isolates is a significant public health concern, as these organisms possess a unique capacity to acquire genetic elements encoding both resistance and hypervirulence. This study aims to investigate the epidemiological, resistance, and virulence characteristics of K. pneumoniae isolates that carry both virulence plasmids and blaOXA-48-like genes in a tertiary hospital in China. A total of 217 clinical isolates of carbapenem-resistant K. pneumoniae (CRKP) were collected between April 2020 and March 2022. The antimicrobial susceptibility test was conducted to evaluate the drug resistance profile. All isolates were screened for the presence of genes encoding carbapenemases (blaKPC, blaNDM, blaIMP, blaVIM, and blaOXA-48-like), ESBLs genes (blaCTX-M, blaSHV, blaTEM), and virulence plasmid pLVPK-borne genes (rmpA, rmpA2, iucA, iroB, and peg344) using polymerase chain reaction (PCR) amplification. Clonal lineages were assigned using multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). The plasmid incompatibility groups were identified using PCR-based replicon typing (PBRT). The transferability of carbapenemase-encoding plasmids and pLVPK-like virulence plasmids was assessed via conjugation. The plasmid location of rmpA2 was determined using S1-Pulsed Field Gel Electrophoresis (S1-PFGE) and southern blotting hybridization. The virulence potential of the isolates was assessed using the string test, capsular serotyping, serum killing assay and a Galleria mellonella larval infection model. Of the 217 CRKP clinical isolates collected, 23% were identified as carrying blaOXA-48-like genes. All blaOXA-48-like isolates exhibited resistance to commonly used clinical antimicrobial agents, except for ceftazidime/avibactam, colistin, tigecycline, trimethoprim-sulfamethOXAzole, polymyxin B, and nitrofurantoin. The main common OXA-48-like carbapenemase enzymes were found to be blaOXA-181 and blaOXA-232. MLST and PFGE fingerprinting analysis revealed clonal transmission and plasmid transmission. OXA-48-like producing CRKP isolates mainly clustered in K64 ST11 and K47 ST15. Results of the string Test, serum killing assay (in vitro) and Galleria mellonella infection model (in vivo) indicated hypervirulence. PBRT showed that the blaOXA-181 and blaOXA-232 producing hypervirulent carbapenem-resistant Klebsiella pneumoniae (Hv-CRKP) were mainly carried on ColE-type, IncF, and IncX3. Eight clinical isolates of hv-CRKP were identified as carrying three carbapenem-resistant genes (blaKPC, blaOXA-181 or OXA-232, and blaNDM-1). Moreover, Southern blotting hybridization revealed that all eight isolates had a pLVPK-like virulent plasmid (138.9-216.9 kb) with an uneven number and size of plasmid. In our investigation, we have observed the emergence of hv-CRKP carrying blaOXA-48-like genes, which identified two genetic relationships: clonal transmission and plasmid transmission. PBRT analysis showed that these genes were mainly carried on ColE-type, IncF, and IncX3 plasmids. These isolates have been shown to be hypervirulent in vitro and in vivo. Additionally, eight clinical isolates of hv-CRKP were identified as carrying three carbapenem-resistant genes (blaKPC, blaOXA-181 or OXA-232, and blaNDM-1) and carrying a pLVPK-like virulent plasmid. Hence, our findings highlight the need for further investigation and active surveillance of hypervirulent OXA-48-like producing Hv-CRKP isolates to control their transmission.

Molecular characteristics of carbapenem-resistant gram-negative bacilli in pediatric patients in China

BackgroundCarbapenem-resistant gram-negative bacilli (CR-GNB) have been increasingly reported in China. However, dynamic monitoring data on molecular epidemiology of CR-GNB are limited in pediatric patients.Results300 CR-GNB isolates (200 Carbapenem-resistant K. pneumoniae (CRKP), 50 carbapenem-resistant A.baumannii (CRAB) and 50 carbapenem-resistant P. aeruginosa (CRPA)) were investigated. The predominant carbapenemase gene was blaNDM−1 (73%) and blaKPC−2 (65%) in neonates and non-neonates. Meanwhile, the predominant STs were ST11 (54%) in neonates and ST17 (27.0%) and ST278 (20.0%) in non-neonates. Notably, a shift in the dominant sequence type of CRKP infections from ST17 /ST278-NDM-1 to ST11-KPC-2 was observed during the years 2017–2021 and KPC-KP showed relatively higher resistance to aminoglycosides and quinolones than NDM-KP.BlaOXA−23 was isolated from all the CRAB isolates while only one isolate expressing blaBIC and 2 isolates expressing blaVIM−2 were found in CRPA isolates. ST195 (22.0%) and ST244 (24.0%) were the most common in CRAB and CRPA isolates and all the STs of CRAB belonged to CC92 while CRPA presents ST types with diversity distribution.ConclusionCRKP showed different molecular phenotypes in neonates and non-neonates and was changing dynamically and high-risk clone of ST11 KPC-KP should be paid more attention. Most CRKP and CRAB strains shared the same CCs, suggesting that intrahospital transmission may occur, and large-scale screening and more effective measures are urgently needed.

In vivo adaptive antimicrobial resistance in Klebsiella pneumoniae during antibiotic therapy.

Klebsiella pneumoniae is one of the leading pathogens contributing to antimicrobial resistance. The emergence of carbapenem-resistant K. pneumoniae (CRKP) has put the use of clinical antimicrobial agents in a dilemma. In particular, CRKP exhibiting resistance to ceftazidime/avibactam, tigecycline and colistin have raised great clinical concern, as these are the last-resort antibiotics for the treatment of CRKP infections. Within-host evolution is a survival strategy closely related to the emergence of antimicrobial resistance, while little attention has been paid to the in vivo genetic process of conversion from antibiotic-susceptible to resistant K. pneumoniae. Here we have a literature review regarding the in vivo evolution of resistance to carbapenems, ceftazidime/avibactam, tigecycline, and colistin in K. pneumoniae during antibacterial therapy, and summarized the detailed resistance mechanisms. In general, acquiring bla KPC and bla NDM harboring-plasmid, specific mutations in bla KPC, and porin genes, such as ompK35 and ompK36, upregulation of bla KPC, contribute to the development of carbapenem and ceftazidime/avibactam resistance in vivo. Overexpression of efflux pumps, acquiring plasmid-carrying tet (A) variants, and ribosomal protein change can lead to the adaptive evolution of tigecycline resistance. Specific mutations in chromosomes result in the cationic substitution of the phosphate groups of lipid A, thus contributing to colistin resistance. The resistant plasmid might be acquired from the co-infecting or co-colonizing strains, and the internal environment and antibiotic selection pressure contribute to the emergence of resistant mutants. The internal environment within the human host could serve as an important source of resistant K. pneumoniae strains.