Klebsiella pneumoniae carriage in low-income countries: antimicrobial resistance, genomic diversity and risk factors

Aligning antimicrobial resistance surveillance with schistosomiasis research: an interlinked One Health approach

One Health surveillance involves the analysis of human, animal and environmental samples, recognising their interconnectedness in health systems. Such considerations are crucial to investigate the transmission of many pathogens, including drug-resistant bacteria and parasites. The highest rates of antimicrobial resistance (AMR)-associated deaths are observed in sub-Saharan Africa, where concurrently the waterborne parasitic disease schistosomiasis can be highly endemic in both humans and animals. Although there is growing acknowledgment of significant interactions between bacteria and parasites, knowledge of relationships between schistosomes, microbes and AMR remains inadequate. In addition, newly emergent research has revealed the previously underappreciated roles of animals and the environment in both AMR and schistosomiasis transmission. We consider shared environmental drivers and colonisation linkage in this narrative review, with a focus on extended-spectrum beta-lactamase-mediated resistance among bacteria from the Enterobacteriaceae family, which is exceedingly prevalent and responsible for a high burden of AMR-associated deaths. Then we examine novel findings from Malawi, where the landscapes of AMR and schistosomiasis are rapidly evolving, and make comparisons to other geographic areas with similar co-infection epidemiology. We identify several knowledge gaps that could be addressed in future research, including the need to characterise the impact of intestinal schistosomiasis and freshwater contact on intestinal AMR colonisation, before proposing a rationale for connecting AMR surveillance and schistosomiasis research within a One Health framework.

Bacteraemia associated with multiple septic localizations caused by Klebsiella pneumoniae sequence type ST660

We report a case of Klebsiella pneumoniae bacteraemia in an 80-year-old man in France with no history of travel to Asia, complicated by endogenous endophthalmitis, multiple cerebral microbleeds and hepatic microabscesses, associated with a Bentall endocarditis. Hypervirulence pathotype was suggested based on clinical picture, bacterial isolate genomic sequence and hypermucoidy. Interestingly, the isolate had the non-K1/K2-capsular serotype locus KL113-like, carried a KpVP-1-like virulence plasmid, and belonged to the emerging sublineage SL660 (comprising the sequence type ST660).

Antimicrobial resistance profiles and genome characteristics of Klebsiella isolated from the faeces of neonates in the neonatal intensive care unit

Introduction. Klebsiella spp. are important bacteria that colonize the human intestine, especially in preterm infants; they can induce local and systemic disease under specific circumstances, including inflammatory bowel disease, necrotizing enterocolitis and colorectal cancer.Hypothesis. Klebsiella spp. colonized in the intestine of the neonates in the neonatal intensive care unit (NICU) may be associated with disease and antibiotic resistance, which will be hazardous to the children.Aim. Our aim was to know about the prevalence, antimicrobial resistance and genome characteristics of Klebsiella spp. in neonate carriers.Methodology. Genome sequencing and analysis, and antimicrobial susceptibility testing were mainly performed in this study.Results. The isolation rates of Klebsiella spp. strains were 3.7% (16/436) in 2014 and 4.3% (18/420) in 2021. Cases with intestinal-colonized Klebsiella spp. were mainly infants with low birth weights or those with pneumonia or hyperbilirubinemia. According to the core-pan genomic analysis, 34 stains showed gene polymorphism and a sequence type (ST) of an emerging high-risk clone (ST11). Eight strains (23.5%) were found to be resistant to 2 or more antibiotics, and 46 genes/gene families along with nine plasmids were identified that conferred resistance to antibiotics. In particular, the two strains were multidrug-resistant. Strain A1256 that is related to Klebsiella quasipneumoniae subsp. similipneumoniae was uncommon, carrying two plasmids similar to IncFII and IncX3 that included five antibiotic resistance genes.Conclusion. The prevention and control of neonatal Klebsiella spp. colonization in the NICU should be strengthened by paying increased attention to preventing antimicrobial resistance in neonates.

Complete genome sequence, phenotypic correlation and pangenome analysis of uropathogenic Klebsiella spp

Urinary tract infections (UTI) by antibiotic resistant and virulent K. pneumoniae are a growing concern. Understanding the genome and validating the genomic profile along with pangenome analysis will facilitate surveillance of high-risk clones of K. pneumoniae to underpin management strategies toward early detection. The present study aims to correlate resistome with phenotypic antimicrobial resistance and virulome with pathogenicity in Klebsiella spp. The present study aimed to perform complete genome sequences of Klebsiella spp. and to analyse the correlation of resistome with phenotypic antimicrobial resistance and virulome with pathogenicity. To understand the resistome, pangenome and virulome in the Klebsiella spp, the ResFinder, CARD, IS Finder, PlasmidFinder, PHASTER, Roary, VFDB were used. The phenotypic susceptibility profiling identified the uropathogenic kp3 to exhibit multi drug resistance. The resistome and in vitro antimicrobial profiling showed concordance with all the tested antibiotics against the study strains. Hypermucoviscosity was not observed for any of the test isolates; this phenotypic character matches perfectly with the absence of rmpA and magA genes. To the best of our knowledge, this is the first report on the presence of ste, stf, stc and sti major fimbrial operons of Salmonella enterica serotype Typhimurium in K. pneumoniae genome. The study identifies the discordance of virulome and virulence in Klebsiella spp. The complete genome analysis and phenotypic correlation identify uropathogenic K. pneumoniae kp3 as a carbapenem-resistant and virulent pathogen. The Pangenome of K. pneumoniae was open suggesting high genetic diversity. Diverse K serotypes were observed. Sequence typing reveals the prevalence of K. pneumoniae high-risk clones in UTI catheterised patients. The study also highlights the concordance of resistome and in vitro susceptibility tests. Importantly, the study identifies the necessity of virulome and phenotypic virulence markers for timely diagnosis and immediate treatment for the management of high-risk K. pneumoniae clones.

Type IV-A3 CRISPR-Cas systems drive inter-plasmid conflicts by acquiring spacers in trans

Plasmid-encoded type IV-A CRISPR-Cas systems lack an acquisition module, feature a DinG helicase instead of a nuclease, and form ribonucleoprotein complexes of unknown biological functions. Type IV-A3 systems are carried by conjugative plasmids that often harbor antibiotic-resistance genes and their CRISPR array contents suggest a role in mediating inter-plasmid conflicts, but this function remains unexplored. Here, we demonstrate that a plasmid-encoded type IV-A3 system co-opts the type I-E adaptation machinery from its host, Klebsiella pneumoniae (K. pneumoniae), to update its CRISPR array. Furthermore, we reveal that robust interference of conjugative plasmids and phages is elicited through CRISPR RNA-dependent transcriptional repression. By silencing plasmid core functions, type IV-A3 impacts the horizontal transfer and stability of targeted plasmids, supporting its role in plasmid competition. Our findings shed light on the mechanisms and ecological function of type IV-A3 systems and demonstrate their practical efficacy for countering antibiotic resistance in clinically relevant strains.

Systematic interrogation of CRISPR antimicrobials in Klebsiella pneumoniae reveals nuclease-, guide- and strain-dependent features influencing antimicrobial activity

CRISPR-Cas systems can be utilized as programmable-spectrum antimicrobials to combat bacterial infections. However, how CRISPR nucleases perform as antimicrobials across target sites and strains remains poorly explored. Here, we address this knowledge gap by systematically interrogating the use of CRISPR antimicrobials using multidrug-resistant and hypervirulent strains of Klebsiella pneumoniae as models. Comparing different Cas nucleases, DNA-targeting nucleases outperformed RNA-targeting nucleases based on the tested targets. Focusing on AsCas12a that exhibited robust targeting across different strains, we found that the elucidated modes of escape varied widely, restraining opportunities to enhance killing. We also encountered individual guide RNAs yielding different extents of clearance across strains, which were linked to an interplay between improper gRNA folding and strain-specific DNA repair and survival. To explore features that could improve targeting across strains, we performed a genome-wide screen in different K. pneumoniae strains that yielded guide design rules and trained an algorithm for predicting guide efficiency. Finally, we showed that Cas12a antimicrobials can be exploited to eliminate K. pneumoniae when encoded in phagemids delivered by T7-like phages. Altogether, our results highlight the importance of evaluating antimicrobial activity of CRISPR antimicrobials across relevant strains and define critical parameters for efficient CRISPR-based targeting.

Environment, animals, and food as reservoirs of antibiotic-resistant bacteria for humans: One health or more?

Antimicrobial resistance (AMR) is a major public health challenge. For several years, AMR has been addressed through a One Health approach that links human health, animal health, and environmental quality. In this review, we discuss AMR in different reservoirs with a focus on the environment. Anthropogenic activities produce effluents (sewage, manure, and industrial wastes) that contaminate soils and aquatic environments with antibiotic-resistant bacteria (ARB), antibiotic-resistant genes (ARGs), and selective agents such as antibiotics, biocides, and heavy metals. Livestock treated with antibiotics can also contaminate food with ARB. In high-income countries (HICs), effective sanitation infrastructure and limited pharmaceutical industries result in more controlled discharges associated with human activities. Hence, studies using genome-based typing methods have revealed that, although rare inter-reservoir transmission events have been reported, human acquisition in HICs occurs primarily through person-to-person transmission. The situation is different in low- and middle-income countries (LMICs) where high population density, poorer sanitation and animal farming practices are more conducive to inter-reservoir transmissions. In addition, environmental bacteria can be a source of ARGs that, when transferred to pathogenic species under antibiotic selection pressure in environmental hotspots, produce new antibiotic-resistant strains that can potentially spread in the human community through human-to-human transmission. The keys to reducing AMR in the environment are (i) better treatment of human waste by improving wastewater treatment plants (WWTPs) in HICs and improving sanitation infrastructure in LMICs, (ii) reducing the use of antibiotics by humans and animals, (iii) prioritizing the use of less environmentally harmful antibiotics, and (iv) better control of pharmaceutical industry waste.

The correlation between intestinal colonization and infection of carbapenem-resistant Klebsiella pneumoniae: A systematic review

As a widely spread Gram-negative bacteria, Klebsiella pneumoniae (KP) mainly causes acquired infections in hospitals, such as lung infections, urinary tract infections, and bloodstream infections. In recent years, the number of multidrug-resistant KP strains has increased dramatically, posing a great threat to human health. Carbapenem-resistant KP (CRKP) can be colonized in human body, especially in gastrointestinal tract, and some colonized patients can be infected during hospitalization, among which invasive operation, underlying disease, admission to intensive care unit, antibiotic use, severity of the primary disease, advanced age, operation, coma, and renal failure are common risk factors for secondary infection. Active screening and preventive measures can effectively prevent the occurrence of CRKP infection. Based on the epidemiological status, this study aims to discuss the correlation between colonization and secondary infection induced by CRKP and risk factors for their happening and provide some reference for nosocomial infection prevention and control.

Epidemiology of bacterial resistance at the Grand Magal of Touba in Senegal

BACKGROUND

The Grand Magal of Touba (GMT) associates with risks of infection, but no study on the circulation of resistant bacteria has yet been conducted.

MATERIALS AND METHODS

qPCR was performed on rectal samples from GMT pilgrims between 2018 and 2021, before and after their participation in the gathering. Rectal samples from between 2018 and 2020 were also cultured on specific media, and antibiotic susceptibility testing was performed.

RESULTS

Forty-one of the 296 (13.8%) pilgrims had at least one gastrointestinal symptom and 91/290 (31.4%) acquired pathogenic bacteria, mostly Escherichia coli. A total of 54.7% of pilgrims reported washing their hands more frequently than usual and 89.2% used soap. One hundred and five (36.2%) acquired at least one resistance gene, notably CTX-M A (21.0%), SHV (16.5%) and TEM (8.2%). The strains isolated by culture were mostly E. coli. These bacteria were found to be sensitive to carbapenems and resistant to amoxicillin and amoxicillin-clavulanic acid. The acquisition of enteroaggregative E. coli was independently associated with CTX-M A and TEM acquisition.

CONCLUSION

Pilgrims presented a risk for acquisition of CTX-M A after the GMT. Surveillance of the prevalence of resistant bacteria and the occurrence of associated clinical infections among pilgrims are necessary in the future.

The Rapid Emergence of Hypervirulent Klebsiella Species and Burkholderia pseudomallei as Major Health Threats in Southeast Asia: The Urgent Need for Recognition as Neglected Tropical Diseases

The World Health Organization (WHO)'s list of neglected tropical diseases (NTDs) highlights conditions that are responsible for devastating health, social and economic consequences, and yet, they are overlooked and poorly resourced. The NTD list does not include conditions caused by Gram-negative bacilli (GNB). Infections due to GNB cause significant morbidity and mortality and are prevalent worldwide. Southeast Asia is a WHO region of low- and middle-income countries carrying the largest burden of NTDs. Two significant health threats in Southeast Asia are Burkholderia pseudomallei (causing melioidosis) and hypervirulent Klebsiella pneumoniae (HvKp). Both diseases have high mortality and increasing prevalence, yet both suffer from a lack of awareness, significant under-resourcing, incomplete epidemiological data, limited diagnostics, and a lack of evidence-based treatment. Emerging evidence shows that both melioidosis and HvKp are spreading globally, including in high-income countries, highlighting the potential future global threat they pose. In this article, we review both conditions, identifying current trends and challenges in Southeast Asia and areas for future research. We also argue that melioidosis and HvKp merit inclusion as NTDs, and that mandatory global surveillance and reporting systems should be established, and we make an urgent call for research to better understand, detect, and treat these neglected diseases.

Swine farming shifted the gut antibiotic resistome of local people

Antibiotic resistance genes (ARGs) are prevalent in the livestock environment, but little is known about impacts of animal farming on the gut antibiotic resistome of local people. Here we conducted metagenomic sequencing to investigate gut microbiome and resistome of residents in a swine farming village as well as environmental relevance by comparing with a nearby non-farming village. Results showed a shift of gut microbiome towards unhealthy status in the residents of swine farming village, with an increased abundance and diversity in pathogens and ARGs. The resistome composition in human guts was more similar with that in swine feces and air than that in soil and water. Mobile gene elements were closely associated with the prevalence of gut resistome. Some plasmid-borne ARGs were colocalized in similar genetic contexts in gut and environmental samples. Metagenomic binning obtained 47 ARGs-carrying families in human guts, and therein Enterobacteriaceae posed the highest threats in antibiotic resistance and virulence. Several ARGs-carrying families were shared by gut and environmental samples (mainly in swine feces and air), and the ARGs were evolutionarily conservative within genera. The findings highlight that swine farming can shape gut resistome of local people with close linkage to farm environmental exposures.

Antibiotic resistance: a global crisis, problems and solutions

Healthy state is priority in today's world which can be achieved using effective medicines. But due to overuse and misuse of antibiotics, a menace of resistance has increased in pathogenic microbes. World Health Organization (WHO) has announced ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) as the top priority pathogens as these have developed resistance against certain antibiotics. To combat such a global issue, it is utmost important to identify novel therapeutic strategies/agents as an alternate to such antibiotics. To name certain antibiotic adjuvants including: inhibitors of beta-lactamase, efflux pumps and permeabilizers for outer membrane can potentially solve the antibiotic resistance problems. In this regard, inhibitors of lytic domain of lytic transglycosylases provide a novel way to not only act as an alternate to antibiotics but also capable of restoring the efficiency of previously resistant antibiotics. Further, use of bacteriophages is another promising strategy to deal with antibiotic resistant pathogens. Taking in consideration the alternatives of antibiotics, a green synthesis nanoparticle-based therapy exemplifies a good option to combat microbial resistance. As horizontal gene transfer (HGT) in bacteria facilitates the evolution of new resistance strains, therefore identifying the mechanism of resistance and development of inhibitors against it can be a novel approach to combat such problems. In our perspective, host-directed therapy (HDT) represents another promising strategy in combating antimicrobial resistance (AMR). This approach involves targeting specific factors within host cells that pathogens rely on for their survival, either through replication or persistence. As many new drugs are under clinical trials it is advisable that more clinical data and antimicrobial stewardship programs should be conducted to fully assess the clinical efficacy and safety of new therapeutic agents.

An Insight into the Exploration of Antibiotic Resistance Genes in Calorie Restricted Diet Fed Mice

Antibiotic resistance genes (ARGs) threaten the success of modern drugs against multidrug resistant infections. ARGs can be transferred to opportunistic pathogens by horizontal gene transfer (HGT). Many studies have investigated the characteristics of ARGs in various chemical stressors. Studies on the effects of dietary nutrition and dietary patterns on ARGs are rare. The study first demonstrated the effect of calorie restricted (CR) diet on the ARGs and mobile genetic elements (MGEs) in mouse feces and explored their relationship with gut microbiota and their functions. The results showed that the abundance of the total ARGs in mouse feces of the CR group increased, especially tetracycline ARGs (tetW-01). The abundance of the MLSB ARGs (ermB) decreased evidently in mouse feces of the CR group. In addition, the total abundance of MGEs decreased evidently in the CR group, especially tnpA-03. In the meantime, the abundance of Lactobacillus and Bifidobacterium in mouse feces of the CR group increased remarkably. The Spearman correlation analysis between gut microbiota and ARGs showed that several probiotics were significantly positively correlated with ARGs (tetW-01), which might be the main contribution to the increase in ARGs of the CR group.

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

Introduction

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.

Methods

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.

Results

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.

Discussion

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.

Repeated cross-sectional study identifies differing risk factors associated with microbial contamination in common food products in the United Kingdom

All foods carry microbes, many of which are harmless, but foods can also carry pathogens and/or microbial indicators of contamination. Limited information exists on the co-occurrence of microbes of food safety concern and the factors associated with their presence. Here, a population-based repeated cross-sectional design was used to determine the prevalence and co-occurrence of Escherichia coli, Klebsiella spp., Salmonella spp. and Vibrio spp. in key food commodities - chicken, pork, prawns, salmon and leafy greens. Prevalence in 1,369 food samples for these four target bacterial genera/species varied, while 25.6% of all samples had at least two of the target bacteria and eight different combinations of bacteria were observed as co-occurrence profiles in raw prawns. Imported frozen chicken was 6.4 times more likely to contain Salmonella than domestic chicken, and imported salmon was 5.5 times more likely to be contaminated with E. coli. Seasonality was significantly associated with E. coli and Klebsiella spp. contamination in leafy greens, with higher detection in summer and autumn. Moreover, the odds of Klebsiella spp. contamination were higher in summer in chicken and pork samples. These results provide insight on the bacterial species present on foods at retail, and identify factors associated with the presence of individual bacteria, which are highly relevant for food safety risk assessments and the design of surveillance programmes.

Occurrence and Molecular Study of Hypermucoviscous/Hypervirulence Trait in Gut Commensal K. pneumoniae from Healthy Subjects

Hypervirulent Klebsiella pneumoniae (hvKp) is emerging worldwide. Hypermucoviscousity is the characteristic trait that distinguishes it from classic K. pneumoniae (cKp), which enables Kp to cause severe invasive infections. This research aimed to investigate the hypermucoviscous Kp (hmvKp) phenotype among gut commensal Kp isolated from healthy individuals and attempted to characterize the genes encoding virulence factors that may regulate the hypermucoviscosity trait. Using the string test, 50 identified Kp isolates from healthy individuals’ stool samples were examined for hypermucoviscosity and investigated by transmission electron microscopy (TEM). Antimicrobial susceptibility profiles of Kp isolates were determined using the Kirby Bauer disc method. Kp isolates were tested for genes encoding different virulence factors by PCR. Biofilm formation was assayed by the microtiter plate method. All Kp isolates were multidrug-resistant (MDR). Phenotypically, 42% of isolates were hmvKp. PCR-based genotypic testing revealed the hmvKp isolates belonged to capsular serotype K2. All study Kp isolates harbored more than one virulence gene. The genes magA and rmpA were not detected, while the terW gene was present in all isolates. The siderophores encoding genes entB and irp2 were most prevalent in hmvKp isolates (90.5%) and non-hmvKp (96.6%), respectively. hmvKp isolates harbored the genes wabG and uge with rates of 90.5% and 85.7%, respectively. The outcomes of this research highlight the potential health risk of commensal Kp to cause severe invasive diseases, owing to being hmvKp and MDR, and harboring multiple virulence genes. The absence of essential genes related to hypermucoviscosity such as magA and rmpA in hmvKp phenotypes suggests the multifactorial complexity of the hypermucoviscosity or hypervirulence traits. Thus, further studies are warranted to verify the hypermucoviscosity-related virulence factors among pathogenic and commensal Kp in different colonization niches.

Prevalence, antibiotic resistance patterns, and biofilm formation ability of Enterobacterales recovered from food of animal origin in Egypt

Background and Aim: The majority of animal-derived food safety studies have focused on foodborne zoonotic agents; however, members of the opportunistic Enterobacteriaceae (Ops) family are increasingly implicated in foodborne and public health crises due to their robust evolution of acquiring antimicrobial resistance and biofilms, consequently require thorough characterization, particularly in the Egyptian food sector. Therefore, this study aimed to determine the distribution and prevalence of Enterobacteriaceae family members in animal-derived foods, as well as their resistance to important antimicrobials and biofilm-forming potential. Materials and Methods: A total of 274 beef, rabbit meat, chicken meat, egg, butter, and milk samples were investigated for the presence of Enterobacteriaceae. All isolated strains were first recognized using traditional microbiological techniques. Following that, matrix-assisted laser desorption ionization-time of flight mass spectrometry was used to validate the Enterobacteriaceae's identity. The isolated enterobacteria strains were tested on disk diffusion and crystal violet quantitative microtiter plates to determine their antibiotic resistance and capacity to form biofilms. Results: There have been thirty isolates of Enterobacteriaceae from seven different species and four genera. Out of the three food types, Pseudomonas aeruginosa had the highest prevalence rate (4.1%). With three species, Enterobacter genera had the second-highest prevalence (3.28%) across five different food categories. In four different food types, the Klebsiella genera had the second-highest distribution and third-highest incidence (2.55%). Almost all isolates, except three Proteus mirabilis, showed prominent levels of resistance, particularly to beta-lactam antibiotics. Except for two Enterobacter cloacae and three P. mirabilis isolates, all isolates were classified as multidrug-resistant (MDR) or extensively multidrug-resistant (XDR). The multiple antibiotic resistance index (MARI) of the majority of isolates dropped between 0.273 and 0.727. The highest MARI was conferred by Klebsiella pneumoniae, at 0.727. Overall, 83.33% of the isolates had strong biofilm capacity, while only 16.67% exhibited moderate capacity. Conclusion: The MDR, XDR, and strong biofilm indicators confirmed in 83.33% of the currently tested Enterobacteriaceae from animal-derived foods suggest that, if not addressed, there may be rising risks to Egypt's economy and public health.

Genetic Diversity of Polymyxin-Resistance Mechanisms in Clinical Isolates of Carbapenem-Resistant Klebsiella pneumoniae: a Multicenter Study in China

Polymyxin has been the last resort to treat multidrug-resistant Klebsiella pneumonia. However, recent studies have revealed that polymyxin-resistant carbapenem-resistant Klebsiella pneumonia (PR-CRKP) emerged due to the mutations in chromosomal genes or the plasmid-harboring mcr gene, leading to lipopolysaccharide modification or efflux of polymyxin through pumps. Further surveillance was required. In the present study we collected PR-CRKP strains from 8 hospitals in 6 provinces/cities across China to identify the carbapenemase and polymyxin resistance genes and epidemiological features by whole-genome sequencing (WGS). The broth microdilution method (BMD) was performed to determine the MIC of polymyxin. Of 662 nonduplicate CRKP strains, 15.26% (101/662) were defined as PR-CRKP; 10 (9.90%) were confirmed as Klebsiella quasipneumoniae by WGS. The strains were further classified into 21 individual sequence types (STs) by using multilocus sequence typing (MLST), with ST11 being prevalent (68/101, 67.33%). Five carbapenemase types were identified among 92 CR-PRKP, blaKPC-2 (66.67%), blaNDM-1 (16.83%), blaNDM-5 (0.99%), blaIMP-4 (4.95%), and blaIMP-38 (0.99%). Notably, 2 PR-CRKP strains harbored both blaKPC-2 and blaNDM-1. The inactivation of mgrB, associated significantly with high-level polymyxin resistance, was mainly caused by the insertion sequence (IS) insertion (62.96%, 17/27). Furthermore, acrR was inserted coincidently by ISkpn26 (67/101, 66.33%). The deletion or splicing mutations of crrCAB were significantly associated with ST11 and KL47 (capsule locus types), and diverse mutations of the ramR gene were identified. Only one strain carried the mcr gene. In summary, the high IS-inserted mgrB inactivation, the close relationship between ST11 and the deletion or splicing mutations of the crrCAB, and the specific features of PR-K. quasipneumoniae constituted notable features of our PR-CRKP strains in China. IMPORTANCE Polymyxin-resistant CRKP is a serious public health threat whose resistance mechanisms should be under continuous surveillance. Here, we collected 662 nonduplicate CRKP strains across China to identify the carbapenemase and polymyxin resistance genes and epidemiological features. Polymyxin resistance mechanism in 101 PR-CRKP strains in China were also investigated, 9.8% of which (10/101) were K. quasipneumoniae, as determined via WGS, and inactivation of mgrB remained the most crucial polymyxin resistance mechanism, significantly related to high-level resistance. Deletion or splicing mutations of crrCAB were significantly associated with ST11 and KL47. Diverse mutations of the ramR gene were identified. The plasmid complementation experiment and mRNA expression analysis further confirmed that the mgrB promoter and ramR played a critical role in polymyxin resistance. This multicenter study contributed to the understanding of antibiotic resistance forms in China.

Highly conserved composite transposon harbouring aerobactin iuc3 in Klebsiella pneumoniae from pigs

Klebsiella pneumoniae is an important opportunistic pathogen associated with severe invasive disease in humans. Hypervirulent K. pneumoniae, which are K. pneumoniae with several acquired virulence determinants such as the siderophore aerobactin and others, are more prominent in countries in South and South-East Asia compared to European countries. This Klebsiella pathotype is capable of causing liver abscesses in immunocompetent persons in the community. K. pneumoniae has not been extensively studied in non-human niches. In the present study, K. pneumoniae isolated from caecal samples (n=299) from healthy fattening pigs in Norway were characterized with regard to population structure and virulence determinants. These data were compared to data from a previous study on K. pneumoniae from healthy pigs in Thailand. Lastly, an in-depth plasmid study on K. pneumoniae with aerobactin was performed. Culturing and whole-genome sequencing was applied to detect, confirm and characterize K. pneumoniae isolates. Phylogenetic analysis described the evolutionary relationship and diversity of the isolates, while virulence determinants and sequence types were detected with Kleborate. Long-read sequencing was applied to obtain the complete sequence of virulence plasmids harbouring aerobactin. A total of 48.8 % of the investigated Norwegian pig caecal samples (n=299) were positive for K. pneumoniae. Acquired virulence determinants were detected in 72.6 % of the isolates, the most prominent being aerobactin (69.2 %), all of which were iuc3. In contrast, only 4.6 % of the isolates from Thailand harboured aerobactin. The aerobactin operon was located on potentially conjugative IncFIB_K/FII_K plasmids of varying sizes in isolates from both countries. A putative, highly conserved composite transposon with a mean length of 16.2 kb flanked by truncated IS3-family IS407-group insertion sequences was detected on these plasmids, harbouring the aerobactin operon as well as several genes that may confer increased fitness in mammalian hosts. This putative composite transposon was also detected in plasmids harboured by K. pneumoniae from several countries and sources, such as human clinical samples. The high occurrence of K. pneumoniae harbouring aerobactin in Norwegian pigs, taken together with international data, suggest that pigs are a reservoir for K. pneumoniae with iuc3. Truncation of the flanking ISKpn78-element suggest that the putative composite transposon has been permanently integrated into the plasmid, and that it is no longer mobilizable.

Detection of maternal transmission of resistant Gram-negative bacteria in a Cambodian hospital setting

Infection with Extended-spectrum beta-lactamase -producing Enterobacterales (ESBL-E) is common in infants and leads to increased intensive care unit admission and mortality, but the role of maternal transmission in colonization of infants is unclear. Using paired isolates from 50 pairs of mothers and neonates admitted to a Cambodian hospital, we investigated antimicrobial resistance in Escherichia coli and Klebsiella pneumoniae using whole genome sequencing. We detected a wide variety of ESBL-E genes present in this population along with high levels of multidrug resistance. From 21 pairs where the same organism was present in both mother and neonate, we identified eight pairs with identical or near-identical isolates from both individuals suggestive of transmission at or around birth, including a pair with transmission of multiple strains. We found no evidence for transmission of plasmids only from mother to infant. This suggests vertical transmission outside hospitals as a common cause of ESBL-E colonization in neonates.

KbvR mutant of Klebsiella pneumoniae affects the synthesis of type 1 fimbriae and provides protection to mice as a live attenuated vaccine

Klebsiella pneumoniae is a leading cause of severe infections in humans and animals, and the emergence of multidrug-resistant strains highlights the need to develop effective vaccines for preventing such infections. Live attenuated vaccines are attractive vaccine candidates available in the veterinary field. We recently characterized that the K. pneumoniae kbvR (Klebsiella biofilm and virulence regulator) mutant was a highly attenuated strain in the mice model. In the present study, the characterization, safety, and protective efficacy of ΔkbvR strain as a live attenuated vaccine were evaluated. The synthesis and activity of type 1 fimbriae were increased in the ΔkbvR strain. All mice inoculated by the subcutaneous route with 105, 106, and 107 colony-forming units (CFU) doses of the ΔkbvR strain survived. Subcutaneous immunization with two doses of 105 or 107 CFU ΔkbvR elicited a robust humoral immune response, and provided protection against the following K. pneumoniae intraperitoneal infection. The antisera of mice immunized with 105 CFU dose improved the opsonophagocytic ability and complement-mediated lysis not only to the same serotype strain but also to the different serotype strain. The passive transfer of antisera from 105 CFU dose-immunized mice provided protection against K. pneumoniae infection. Overall, our results suggest the great potential of the ΔkbvR strain as a novel vaccine candidate against K. pneumoniae infections in herds or humans.

Limited Transmission of Klebsiella pneumoniae among Humans, Animals, and the Environment in a Caribbean Island, Guadeloupe (French West Indies)

Guadeloupe (French West Indies), a Caribbean island, is an ideal place to study the reservoirs of the Klebsiella pneumoniae species complex (KpSC) and identify the routes of transmission between human and nonhuman sources due to its insularity, small population size, and small area. Here, we report an analysis of 590 biological samples, 546 KpSC isolates, and 331 genome sequences collected between January 2018 and May 2019. The KpSC appears to be common whatever the source. Extended-spectrum-β-lactamase (ESBL)-producing isolates (21.4%) belonged to K. pneumoniae sensu stricto (phylogroup Kp1), and all but one were recovered from the hospital setting. The distribution of species and phylogroups across the different niches was clearly nonrandom, with a distinct separation of Kp1 and Klebsiella variicola (Kp3). The most frequent sequence types (STs) (≥5 isolates) were previously recognized as high-risk multidrug-resistant (MDR) clones, namely, ST17, ST307, ST11, ST147, ST152, and ST45. Only 8 out of the 63 STs (12.7%) associated with human isolates were also found in nonhuman sources. A total of 22 KpSC isolates were defined as hypervirulent: 15 associated with human infections (9.8% of all human isolates), 4 (8.9%) associated with dogs, and 3 (15%) associated with pigs. Most of the human isolates (33.3%) belonged to the globally successful sublineage CG23-I. ST86 was the only clone shared by a human and a nonhuman (dog) source. Our work shows the limited transmission of KpSC isolates between human and nonhuman sources and points to the hospital setting as a cornerstone of the spread of MDR clones and antibiotic resistance genes. IMPORTANCE In this study, we characterized the presence and genomic features of isolates of the Klebsiella pneumoniae species complex (KpSC) from human and nonhuman sources in Guadeloupe (French West Indies) in order to identify the reservoirs and routes of transmission. This is the first study in an island environment, an ideal setting that limits the contribution of external imports. Our data showed the limited transmission of KpSC isolates between the different compartments. In contrast, we identified the hospital setting as the epicenter of antibiotic resistance due to the nosocomial spread of successful multidrug-resistant (MDR) K. pneumoniae clones and antibiotic resistance genes. Ecological barriers and/or limited exposure may restrict spread from the hospital setting to other reservoirs and vice versa. These results highlight the need for control strategies focused on health care centers, using genomic surveillance to limit the spread, particularly of high-risk clones, of this important group of MDR pathogens.

Detection of Klebsiella pneumoniae human gut carriage: a comparison of culture, qPCR, and whole metagenomic sequencing methods

Klebsiella pneumoniae is an important opportunistic healthcare-associated pathogen and major contributor to the global spread of antimicrobial resistance. Gastrointestinal colonization with K. pneumoniae is a major predisposing risk factor for infection and forms an important hub for the dispersal of resistance. Current culture-based detection methods are time consuming, give limited intra-sample abundance and strain diversity information, and have uncertain sensitivity. Here we investigated the presence and abundance of K. pneumoniae at the species and strain level within fecal samples from 103 community-based adults by qPCR and whole metagenomic sequencing (WMS) compared to culture-based detection. qPCR demonstrated the highest sensitivity, detecting K. pneumoniae in 61.2% and 75.8% of direct-fecal and culture-enriched sweep samples, respectively, including 52/52 culture-positive samples. WMS displayed lower sensitivity, detecting K. pneumoniae in 71.2% of culture-positive fecal samples at a 0.01% abundance cutoff, and was inclined to false positives in proportion to the relative abundance of other Enterobacterales present. qPCR accurately quantified K. pneumoniae to 16 genome copies/reaction while WMS could estimate relative abundance to at least 0.01%. Quantification by both methods correlated strongly with each other (Spearman's rho = 0.91). WMS also supported accurate intra-sample K. pneumoniae sequence type (ST)-level diversity detection from fecal microbiomes to 0.1% relative abundance, agreeing with the culture-based detected ST in 16/19 samples. Our results show that qPCR and WMS are sensitive and reliable tools for detection, quantification, and strain analysis of K. pneumoniae from fecal samples with potential to support infection control and enhance insights in K. pneumoniae gastrointestinal ecology.

The human gut serves as a reservoir of hypervirulent Klebsiella pneumoniae

Hypervirulent Klebsiella pneumoniae (hvKp) can cause serious infections and has been increasingly reported clinically. However, we still lack the knowledge to what degree hvKp colonize the community. In this study, we investigated colonization of hvKp in healthy human gut and the relationship between gut hvKp and clinically important invasive strains. We compile global genomes of gut K. pneumoniae for in-depth genetic analysis and found most hvKp genomes originated from Chinese datasets; therefore, we collected gut K. pneumoniae isolates from healthy people around China. The results revealed a moderate carriage rate of hvKp in the healthy population (4%-5.19%). Phylogenetic analysis indicated a close relationship between gut hvKp and fatal clinical strains. These results demonstrate that the human gut may serve as a reservoir of hvKp and that gut hvKp can play a role in infection of other body parts.

Genomic epidemiological analysis of Klebsiella pneumoniae from Portuguese hospitals reveals insights into circulating antimicrobial resistance

Klebsiella pneumoniae (Kp) bacteria are an increasing threat to public health and represent one of the most concerning pathogens involved in life-threatening infections and antimicrobial resistance (AMR). To understand the epidemiology of AMR of Kp in Portugal, we analysed whole genome sequencing, susceptibility testing and other meta data on 509 isolates collected nationwide from 16 hospitals and environmental settings between years 1980 and 2019. Predominant sequence types (STs) included ST15 (n = 161, 32%), ST147 (n = 36, 7%), ST14 (n = 26, 5%) or ST13 (n = 26, 5%), while 31% of isolates belonged to STs with fewer than 10 isolates. AMR testing revealed widespread resistance to aminoglycosides, fluoroquinolones, cephalosporins and carbapenems. The most common carbapenemase gene was bla_KPC-3. Whilst the distribution of AMR linked plasmids appears uncorrelated with ST, their frequency has changed over time. Before year 2010, the dominant plasmid group was associated with the extended spectrum beta-lactamase gene bla_CTX-M-15, but this group appears to have been displaced by another carrying the bla_KPC-3 gene. Co-carriage of bla_CTX-M and bla_KPC-3 was uncommon. Our results from the largest genomics study of Kp in Portugal highlight the active transmission of strains with AMR genes and provide a baseline set of variants for future resistance monitoring and epidemiological studies.

Intestinal colonisation with hypervirulent or third-generation cephalosporin-resistant Klebsiella pneumoniae strains upon hospital admission in a general ward in Taiwan

We aimed to investigate the clinical characteristics of patients with hypervirulent and/or third-generation cephalosporin-resistant (3GCR) Klebsiella pneumoniae intestinal colonisation upon admission to a general ward at the Taipei Veterans General Hospital in Taiwan in 2017. Stool surveillance culture was obtained from the patients, and clinical characteristics of these patients were studied retrospectively. The K. pneumoniae strains were characterised for antimicrobial susceptibility, mechanisms of the 3GCR phenotype, and the presence of rmpA/A2 genes, which are markers of hypervirulent strains. Whole genome sequencing (WGS) was used to identify the relationship between the colonising and subsequent infection strains. Of the 408 patients admitted to the general ward, 87 patients with intestinal K. pneumoniae colonisation were identified. Twenty-eight (32.2 %) and nine (10.3 %) patients carried 3GCR and hypervirulent K. pneumoniae strains, respectively. Long-term care facility residents and diabetes mellitus were more common in patients colonised with 3GCR strains than those with hypervirulent strains. The 28-d mortality rate was similar between the two groups. The major resistance mechanisms among the 3GCR strains involved the production of extended-spectrum beta-lactamases genes (67.9 %) and bla_DHA-1 (64.3 %). One patient colonised with K. pneumoniae developed subsequent bacteraemia caused by the same strain. In conclusion, 3GCR strains were more common than hypervirulent strains in the patients, but the clinical outcomes were similar. Future studies to elucidate the risk factors for intestinal carriage of hypervirulent and 3GCR K. pneumoniae strains are needed for early identification and better management of these patients.

High Prevalence of bla CTXM-1/IncI1-Iγ/ST3 Plasmids in Extended-Spectrum β-Lactamase-Producing Escherichia coli Isolates Collected From Domestic Animals in Guadeloupe (French West Indies)

Extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) have been classified in the group of resistant bacteria of highest priority. We determined the prevalence of ESBL-E collected in feces from household and shelter pets in Guadeloupe (French West Indies). A single rectal swab was taken from 125 dogs and 60 cats between June and September 2019. The prevalence of fecal carriage of ESBL-E was 7.6% (14/185, 95% CI: 4.2-12.4), within the range observed worldwide. The only risk factor associated with a higher prevalence of ESBL-E rectal carriage was a stay in a shelter, suggesting that refuges could be hotspots for their acquisition. All but one (Klebsiella pneumoniae from a cat) were Escherichia coli. We noted the presence of a bla _CTX-M-1/IncI1-Iγ/sequence type (ST3) plasmid in 11 ESBL-producing E. coli isolates belonging to ST328 (n = 6), ST155 (n = 4) and ST953 (n = 1). A bla _CTX-M-15 gene was identified in the three remaining ESBL-E isolates. The bla _CTX-M-1 and most of the antimicrobial resistance genes were present in a well-conserved large conjugative IncI1-Iγ/ST3 plasmid characterized by two accessory regions containing antibiotic resistance genes. The plasmid has been detected worldwide in E. coli isolates from humans and several animal species, such as food-producing animals, wild birds and pets, and from the environment. This study shows the potential role of pets as a reservoir of antimicrobial-resistant bacteria or genes for humans and underlines the importance of basic hygiene measures by owners of companion animals.

Characterization of Klebsiella pneumoniae isolated from patients suspected of pulmonary or bubonic plague during the Madagascar epidemic in 2017

Klebsiella pneumoniae can lead to a wide range of diseases including pneumonia, bloodstream and urinary tract infections. During a short period of a pulmonary plague epidemic in October 2017 in Madagascar, 12 K. pneumoniae isolates were identified in ten sputum and two buboes aspirate samples. These isolates were from 12 patients suspected of plague, without epidemiological relationships, but were negative for Yersinia pestis in culture. Data were collected from the plague national surveillance system. The isolates were characterized by antimicrobial susceptibility testing and whole-genome sequencing. Real-time PCR was performed to confirm the presence of K. pneumoniae DNA in buboes. All isolates were identified as K. pneumoniae sensu stricto. Five isolates were extended-spectrum β-lactamases producers; eleven different sequence types were identified. Five isolates belonged to known hypervirulent sequence types. Our results demonstrate community-acquired pneumonia caused by K. pneumoniae isolates in patients suspected of plague stressing the importance of bed-side differential diagnosis.

Hybrid Plasmids Encoding Antimicrobial Resistance and Virulence Traits Among Hypervirulent Klebsiella pneumoniae ST2096 in India

Background

Hypervirulent variants of Klebsiella pneumoniae (HvKp) were typically associated with a broadly antimicrobial susceptible clone of sequence type (ST) 23 at the time of its emergence. Concerningly, HvKp is now also emerging within multidrug-resistant (MDR) clones, including ST11, ST15, and ST147. MDR-HvKp either carry both the virulence and resistance plasmids or carry a large hybrid plasmid coding for both virulence and resistance determinants. Here, we aimed to genetically characterize a collection of MDR-HvKp ST2096 isolates haboring hybrid plasmids carrying both antimicrobial resistance (AMR) and virulence genes.

Methods

Nine K. pneumoniae ST2096 isolated over 1 year from the blood sample of hospitalized patients in southern India that were MDR and suspected to be HvKp were selected. All nine isolates were subjected to short-read whole-genome sequencing; a subset (n = 4) was additionally subjected to long-read sequencing to obtain complete genomes for characterization. Mucoviscosity assay was also performed for phenotypic assessment.

Results

Among the nine isolates, seven were carbapenem-resistant, two of which carried bla_NDM-5 on an IncFII plasmid and five carried bla_OXA-232 on a ColKP3 plasmid. The organisms were confirmed as HvKp, with characteristic virulence genes (rmpA2, iutA, and iucABCD) carried on a large (~320 kbp) IncFIB–IncHI1B co-integrate. This hybrid plasmid also carried the aadA2, armA, bla_OXA-1, msrE, mphE, sul1, and dfrA14 AMR genes in addition to the heavy-metal resistance genes. The hybrid plasmid showed about 60% similarity to the IncHI1B virulence plasmid of K. pneumoniae SGH10 and ~70% sequence identity with the first identified IncHI1B pNDM-MAR plasmid. Notably, the hybrid plasmid carried its type IV-A3 CRISPR-Cas system which harbored spacer regions against traL of IncF plasmids, thereby preventing their acquisition.

Conclusion

The convergence of virulence and AMR is clinically concerning in K. pneumoniae. Our data highlight the role of hybrid plasmids carrying both AMR and virulence genes in K. pneumoniae ST2096, suggesting that MDR-HvKp is not confined to selected clones; we highlight the continued emergence of such genotypes across the species. The convergence is occurring globally amidst several clones and is of great concern to public health.

Multicenter Surveillance of Capsular Serotypes, Virulence Genes, and Antimicrobial Susceptibilities of Klebsiella pneumoniae Causing Bacteremia in Taiwan, 2017–2019

We conducted a longitudinal epidemiological surveillance of hypervirulent Klebsiella pneumoniae (hvKP) in Taiwan. Bacteremic KP isolates collected from 16 hospitals in Taiwan between 2017 and 2019 were collected, and the virulent serotypes (K1, K2, K20, K54, and K57), antimicrobial susceptibilities, and virulence genes of these isolates were investigated. During the 3-year period, 1,310 bacteremic KP isolates were collected, of which 27.5% belonged to virulent serotypes, including K1 (n = 162), K2 (n = 74), K57 (n = 56), K54 (n = 41), and K20 (n = 27). K1 was the most prevalent capsular serotype, with an annual prevalence of 11–15%, and was equally distributed across the four geographic areas. The prevalence of K2 declined significantly in 2019. According to wzi-K typing results, 87% of K1 isolates were classified as wzi-1. Among K2 isolates, wzi-72 (55.4%) and wzi-2 (41.9%) were the most common, whereas wzi-206 was the most prevalent (48.2%) among K57 isolates, followed by wzi-77 (25.0%). Wzi-115 accounted for 85.4% of the K54 isolates, whereas wzi-95 accounted for 92.6% of K20 isolates. rmpA was present in 99.4% of K1, 98.6% of K2, 89.3% of K57, 78.0% of K54, and 84.0% of K20 isolates. rmpA2 was present in 100% of K1 and 98.6% of K2 isolates but was only present in 64.3% of K57, 58.5% of K54, and 74.1% of K20 isolates. K1 remains the dominant hvKP serotype and is associated with most virulence genes in Taiwan. Further studies are required to elucidate the significance of other virulent serotypes.

High Prevalence of Klebsiella pneumoniae in European Food Products: a Multicentric Study Comparing Culture and Molecular Detection Methods

The Klebsiella pneumoniae species complex (KpSC) is a leading cause of multidrug-resistant human infections. To better understand the potential contribution of food as a vehicle of KpSC, we conducted a multicentric study to define an optimal culture method for its recovery from food matrices and to characterize food isolates phenotypically and genotypically. Chicken meat (n = 160) and salad (n = 145) samples were collected in five European countries and screened for the presence of KpSC using culture-based and zur-khe intergenic region (ZKIR) quantitative PCR (qPCR) methods. Enrichment using buffered peptone water followed by streaking on Simmons citrate agar with inositol (44°C for 48 h) was defined as the most suitable selective culture method for KpSC recovery. A high prevalence of KpSC was found in chicken meat (60% and 52% by ZKIR qPCR and the culture approach, respectively) and salad (30% and 21%, respectively) samples. Genomic analyses revealed high genetic diversity with the dominance of phylogroups Kp1 (91%) and Kp3 (6%). A total of 82% of isolates presented a natural antimicrobial susceptibility phenotype and genotype, with only four CTX-M-15-producing isolates detected. Notably, identical genotypes were found across samples-same food type and same country (15 cases), different food types and same country (1), and same food type and two countries (1)-suggesting high rates of transmission of KpSC within the food sector. Our study provides a novel isolation strategy for KpSC from food matrices and reinforces the view of food as a potential source of KpSC colonization in humans. IMPORTANCE Bacteria of the Klebsiella pneumoniae species complex (KpSC) are ubiquitous, and K. pneumoniae is a leading cause of antibiotic-resistant infections in humans. Despite the urgent public health threat represented by K. pneumoniae, there is a lack of knowledge of the contribution of food sources to colonization and subsequent infection in humans. This is partly due to the absence of standardized methods for characterizing the presence of KpSC in food matrices. Our multicentric study provides and implements a novel isolation strategy for KpSC from food matrices and shows that KpSC members are highly prevalent in salads and chicken meat, reinforcing the view of food as a potential source of KpSC colonization in humans. Despite the large genetic diversity and the low levels of resistance detected, the occurrence of identical genotypes across samples suggests high rates of transmission of KpSC within the food sector, which need to be further explored to define possible control strategies.

Carbapenemase Production and Epidemiological Characteristics of Carbapenem-Resistant Klebsiella pneumoniae in Western Chongqing, China

Background

This study aimed to determine the molecular characteristics of carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates in a hospital in western Chongqing, southwestern China.

Methods

A total of 127 unique CRKP isolates were collected from the Yongchuan Hospital of Chongqing Medical University, identified using a VITEK-2 compact system, and subjected to microbroth dilution to determine the minimal inhibitory concentration. Enterobacteriaceae intergenic repeat consensus polymerase chain reaction and multilocus sequence typing were used to analyze the homology among the isolates. Genetic information, including resistance and virulence genes, was assessed using polymerase chain reaction. The genomic features of the CRKP carrying gene bla_KPC-2 were detected using whole-genome sequencing.

Results

ST11 was the dominant sequence type in the homology comparison. The resistance rate to ceftazidime-avibactam in children was much higher than that in adults as was the detection rate of the resistance gene bla_NDM (p < 0.0001). Virulence genes such as mrkD (97.6%), uge (96.9%), kpn (96.9%), and fim-H (84.3%) had high detection rates. IncF (57.5%) was the major replicon plasmid detected, and sequencing showed that the CRKP063 genome contained two plasmids. The plasmid carrying bla_KPC-2, which mediates carbapenem resistance, was located on the 359,625 base pair plasmid IncFII, together with virulence factors, plasmid replication protein (rep B), stabilizing protein (par A), and type IV secretion system (T4SS) proteins that mediate plasmid conjugation transfer.

Conclusion

Our study aids in understanding the prevalence of CRKP in this hospital and the significant differences between children and adults, thus providing new ideas for clinical empirical use of antibiotics.

A large-scale genomic snapshot of Klebsiella spp. isolates in Northern Italy reveals limited transmission between clinical and non-clinical settings

The Klebsiella group, found in humans, livestock, plants, soil, water and wild animals, is genetically and ecologically diverse. Many species are opportunistic pathogens and can harbour diverse classes of antimicrobial resistance genes. Healthcare-associated Klebsiella pneumoniae clones that are non-susceptible to carbapenems can spread rapidly, representing a high public health burden. Here we report an analysis of 3,482 genome sequences representing 15 Klebsiella species sampled over a 17-month period from a wide range of clinical, community, animal and environmental settings in and around the Italian city of Pavia. Northern Italy is a hotspot for hospital-acquired carbapenem non-susceptible Klebsiella and thus a pertinent setting to examine the overlap between isolates in clinical and non-clinical settings. We found no genotypic or phenotypic evidence for non-susceptibility to carbapenems outside the clinical environment. Although we noted occasional transmission between clinical and non-clinical settings, our data point to a limited role of animal and environmental reservoirs in the human acquisition of Klebsiella spp. We also provide a detailed genus-wide view of genomic diversity and population structure, including the identification of new groups.

A nationwide genomic study of clinical Klebsiella pneumoniae in Norway 2001-15: introduction and spread of ESBLs facilitated by clonal groups CG15 and CG307

Objectives

To use the nationwide Norwegian surveillance programme on resistant microbes in humans (NORM) to address longitudinal changes in the population structure of Klebsiella pneumoniae isolates from 2001–15, focusing on the emergence and dissemination of ESBL-producing K. pneumoniae in Norway.

Methods

Among blood (n = 6124) and urinary tract (n = 5496) surveillance isolates from 2001–15, we used Illumina technology to whole genome sequence 201 ESBL-producing isolates from blood (n = 130) and urine (n = 71), and 667 non-ESBL isolates from blood. Complete genomes for four isolates were resolved with Oxford Nanopore sequencing.

Results

In a highly diverse collection, Klebsiella variicola ssp. variicola caused 24.5% of Klebsiella pneumoniae species complex (KpSC) bacteraemias. ESBL production was limited to K. pneumoniae sensu stricto (98.5%). A diverse ESBL population of 57 clonal groups (CGs) were dominated by MDR CG307 (17%), CG15 (12%), CG70 (6%), CG258 (5%) and CG45 (5%) carrying bla_CTX-M-15. Yersiniabactin was significantly more common in ESBL-positive (37.8%) compared with non-ESBL K. pneumoniae sensu stricto isolates (12.7%), indicating convergence of virulence and resistance determinants. Moreover, we found a significantly lower prevalence of yersiniabactin (3.0%, 37.8% and 17.3%), IncFIB (58.7%, 87.9% and 79.4%) and IncFII plasmid replicons (40.5%, 82.8% and 54.2%) in K. variicola ssp. variicola compared with ESBL- and non-ESBL K. pneumoniae sensu stricto isolates, respectively.

Conclusions

The increase in Norwegian ESBL-producing KpSC during 2010–15 was driven by CG307 and CG15 carrying bla_CTX-M-15. K. variicola ssp. variicola was a frequent cause of invasive KpSC infection, but rarely carried ESBLs.

Rapid Genomic Characterization and Global Surveillance of Klebsiella Using Pathogenwatch

BACKGROUND

Klebsiella species, including the notable pathogen K. pneumoniae, are increasingly associated with antimicrobial resistance (AMR). Genome-based surveillance can inform interventions aimed at controlling AMR. However, its widespread implementation requires tools to streamline bioinformatic analyses and public health reporting.

METHODS

We developed the web application Pathogenwatch, which implements analytics tailored to Klebsiella species for integration and visualization of genomic and epidemiological data. We populated Pathogenwatch with 16 537 public Klebsiella genomes to enable contextualization of user genomes. We demonstrated its features with 1636 genomes from 4 low- and middle-income countries (LMICs) participating in the NIHR Global Health Research Unit (GHRU) on AMR.

RESULTS

Using Pathogenwatch, we found that GHRU genomes were dominated by a small number of epidemic drug-resistant clones of K. pneumoniae. However, differences in their distribution were observed (eg, ST258/512 dominated in Colombia, ST231 in India, ST307 in Nigeria, ST147 in the Philippines). Phylogenetic analyses including public genomes for contextualization enabled retrospective monitoring of their spread. In particular, we identified hospital outbreaks, detected introductions from abroad, and uncovered clonal expansions associated with resistance and virulence genes. Assessment of loci encoding O-antigens and capsule in K. pneumoniae, which represent possible vaccine candidates, showed that 3 O-types (O1-O3) represented 88.9% of all genomes, whereas capsule types were much more diverse.

CONCLUSIONS

Pathogenwatch provides a free, accessible platform for real-time analysis of Klebsiella genomes to aid surveillance at local, national, and global levels. We have improved representation of genomes from GHRU participant countries, further facilitating ongoing surveillance.

Exploring Klebsiella pneumoniae in Healthy Poultry Reveals High Genetic Diversity, Good Biofilm-Forming Abilities and Higher Prevalence in Turkeys Than Broilers

Klebsiella pneumoniae is a well-studied human pathogen for which antimicrobial resistant and hypervirulent clones have emerged globally. K. pneumoniae is also present in a variety of environmental niches, but currently there is a lack of knowledge on the occurrence and characteristics of K. pneumoniae from non-human sources. Certain environmental niches, e.g., animals, may be associated with high K. pneumoniae abundance, and these can constitute a reservoir for further transmission of strains and genetic elements. The aim of this study was to explore and characterize K. pneumoniae from healthy broilers and turkeys. A total of 511 cecal samples (broiler n = 356, turkey n = 155), included in the Norwegian monitoring program for antimicrobial resistance (AMR) in the veterinary sector (NORM-VET) in 2018, were screened for K. pneumoniae by culturing on SCAI agar. K. pneumoniae was detected in 207 (40.5%) samples. Among the broiler samples, 25.8% were positive for K. pneumoniae, in contrast to turkey with 74.2% positive samples (p < 0.01). Antibiotic susceptibility testing was performed, in addition to investigating biofilm production. Whole genome sequencing was performed on 203 K. pneumoniae isolates, and analysis was performed utilizing comparative genomics tools. The genomes grouped into 66 sequence types (STs), with ST35, ST4710 and ST37 being the most prevalent at 13.8%, 7.4%, and 5.4%, respectively. The overall AMR occurrence was low, with only 11.3% of the isolates showing both pheno- and genotypic resistance. Genes encoding aerobactin, salmochelin or yersiniabactin were detected in 47 (23.2%) genomes. Fifteen hypervirulent genomes belonging to ST4710 and isolated from turkey were identified. These all encoded the siderophore virulence loci iuc5 and iro5 on an IncF plasmid. Isolates from both poultry species displayed good biofilm-forming abilities with an average of OD₅₉₅ 0.69 and 0.64. To conclude, the occurrence of K. pneumoniae in turkey was significantly higher than in broiler, indicating that turkey might be an important zoonotic reservoir for K. pneumoniae compared to broilers. Furthermore, our results show a highly diverse K. pneumoniae population in poultry, low levels of antimicrobial resistance, good biofilm-forming abilities and a novel hypervirulent ST4710 clone circulating in the turkey population.

Current Stage in the Development of Klebsiella pneumoniae Vaccines

Klebsiella pneumoniae is a bacterium capable of colonizing mucous membranes, causing serious infections. Widespread antibiotic resistance in K. pneumoniae—either through intrinsic mechanisms or via acquisition from different species, especially in hospital environments—limits the therapeutic options against this pathogen, further aggravating the disease burden. To date, there are no vaccines available against K. pneumoniae infection. Although formulations based on capsular polysaccharides have been proposed, the high variability in capsular serotypes limits vaccine coverage. Recombinant vaccines based on surface exposed bacterial antigens are a promising alternative owing to their conservation among different serotypes and accessibility to the immune system. Many vaccine candidates have been proposed, some of which have reached clinical trials. The present review summarizes the current status of K. pneumoniae vaccine development. Different strategies including whole cell vaccines, outer membrane vesicles (OMVs), ribosome, polysaccharide, lipopolysaccharide (LPS), and protein-based formulations are discussed. The contribution of antibody and cell-mediated responses is also presented. In summary, K. pneumoniae vaccines are feasible and a promising strategy to prevent infections and to reduce the antimicrobial resistance burden worldwide.

Role of new antibiotics for KPC-producing Klebsiella pneumoniae

Klebsiella pneumoniae has accumulated a wide range of resistance determinants and has evolved into a difficult-to-treat pathogen that poses an increasing healthcare threat. KPC is an important marker for extensively drug-resistant (XDR) organisms with limited treatment options. In response to the medical need for new treatment options, several new antibiotics have been developed and registered recently. The β-lactamase inhibitor (BLI) combinations ceftazidime/avibactam, meropenem/vaborbactam and imipenem/relebactam, the cephalosporin-siderophore conjugate cefiderocol, the aminoglycoside derivative plazomicin and the tetracycline derivative eravacycline, focus on carbapenem-resistant Enterobacterales. These modified agents from old antibiotic classes illustrate the challenges of this requirement to address class-specific resistance mechanisms while critical gaps and some cross-resistance within a class, or to unrelated antibiotic classes, remain. The diverse molecular mechanisms and increasing diversification of carbapenem resistance among Klebsiella isolates requires improved rapid molecular diagnostic capabilities and stringent stewardship programmes to preserve the efficacy of new antibiotics for as long as possible.

Gastrointestinal carriage of Klebsiella pneumoniae in a general adult population: a cross-sectional study of risk factors and bacterial genomic diversity

Antibiotic resistant Klebsiella pneumoniae is a leading public health threat and gastrointestinal carriage is an established risk factor for subsequent infections during hospitalization. Our study contributes new knowledge of risk factors for gastrointestinal carriage and the genomic population structure of K. pneumoniae colonizing humans in a representative sample of a general population in a community setting. Altogether, 2,975 participants (54% women) >40 y in the population-based Tromsø Study: Tromsø7, Norway (2015-2016) were included. Fecal samples were screened for K. pneumoniae, which were characterized using whole-genome sequencing. Risk factors for carriage were analyzed using multivariable logistic regression on data from questionnaires and the Norwegian Prescription Database. Prevalence of K. pneumoniae gastrointestinal carriage was 16.3% (95% CI 15.0-17.7, no gender difference). Risk factors associated with carriage included age ≥60 y, travel to Greece or Asia past 12 months (adjusted odds ratio 1.49, 95% CI 1.11-2.00), Crohn's disease/ulcerative colitis (2.26, 1.20-4.27), use of proton pump inhibitors (1.62, 1.18-2.22) and non-steroidal anti-inflammatory drugs past 6 months (1.38, 1.04-1.84), and antibiotic use the last month (1.73, 1.05-2.86). Prevalence was higher among those having used combinations of drug classes and decreased over time with respect to preceding antibiotic use. The K. pneumoniae population was diverse with 300 sequence types among 484 isolates distributed across four phylogroups. Only 5.2% of isolates harbored acquired resistance and 11.6% had virulence factors. Identification of risk factors for gastrointestinal carriage allows for identification of individuals that may have higher risk of extraintestinal infection during hospitalization. The findings that specific diseases and drugs used were associated with carriage show an impact of these possibly through modulating the human gut microbiota promoting colonization. The diverse population structure of carriage isolates reflects the ecologically adaptive capacity of the bacterium and challenges for vaccine prospects and the identification of reservoirs as a potential source for human colonization.

Genomic Epidemiology of Carbapenemase Producing Klebsiella pneumoniae Strains at a Northern Portuguese Hospital Enables the Detection of a Misidentified Klebsiella variicola KPC-3 Producing Strain

The evolutionary epidemiology, resistome, virulome and mobilome of thirty-one multidrug resistant Klebsiella pneumoniae clinical isolates from the northern Vila Real region of Portugal were characterized using whole-genome sequencing and bioinformatic analysis. The genomic population structure was dominated by two main sequence types (STs): ST147 (n = 17; 54.8%) and ST15 (n = 6; 19.4%) comprising four distinct genomic clusters. Two main carbapenemase coding genes were detected (blaKPC-3 and blaOXA-48) along with additional extended-spectrum β-lactamase coding loci (blaCTX-M-15, blaSHV-12, blaSHV-27, and blaSHV-187). Moreover, whole genome sequencing enabled the identification of one Klebsiella variicola KPC-3 producer isolate previously misidentified as K. pneumoniae, which in addition to the blaKPC-3 carbapenemase gene, bore the chromosomal broad spectrum β-lactamase blaLEN-2 coding gene, oqxAB and fosA resistance loci. The blaKPC-3 genes were located in a Tn4401b transposon (K. variicolan = 1; K. pneumoniaen = 2) and Tn4401d isoform (K. pneumoniaen = 28). Overall, our work describes the first report of a blaKPC-3 producing K. variicola, as well as the detection of this species during infection control measures in surveillance cultures from infected patients. It also highlights the importance of additional control measures to overcome the clonal dissemination of carbapenemase producing clones.

Fecal Klebsiella pneumoniae Carriage Is Intermittent and of High Clonal Diversity

The Klebsiella pneumoniae complex comprises several closely related entities, which are ubiquitous in the natural environment, including in plants, animals, and humans. K. pneumoniae is the major species within this complex. K. pneumoniae strains are opportunistic pathogens and a common cause of healthcare-associated infections. K. pneumoniae can colonize the human gastrointestinal tract, which may become a reservoir for infection. The aim of this study was to investigate the fecal K. pneumoniae carriage in six healthy individuals during a 1 year period. Stool samples were obtained once a week. Using direct and pre-enriched cultures streaked on ampicillin-supplemented agar plates, up to eight individual colonies per positive sample were selected for further characterization. Whole genome sequencing (WGS) was performed for strain characterization. Sequence type (ST), core genome complex type (CT), K and O serotypes, virulence traits, antibiotic resistance profiles, and plasmids were extracted from WGS data. In total, 80 K. pneumoniae isolates were obtained from 48 positive cultures of 278 stool samples from five of the six test subjects. The samples of the five colonized volunteers yielded at most two, three, four (two persons), and five different strains, respectively. These 80 K. pneumoniae isolates belonged to 60 STs, including nine new STs; they were of 70 CTs, yielded 48 K serotypes, 11 O serotypes, and 39 wzc and 51 wzi alleles. Four of the five subjects harbored serotypes K20 and K47, as well as STs ST37, ST101, ST1265, and ST20, which had previously been linked to high-risk K. pneumoniae clones. In total, 25 genes conferring antibiotic resistance and 42 virulence genes were detected among all 80 isolates. Plasmids of 15 different types were found among 65 of the isolates. Fecal carriage of individual strains was of short duration: 70 strains were found on a single sampling day only, and 5 strains were isolated in samples collected over two consecutive weeks. Two of the five colonized individuals—working colleagues having meals together—shared identical K. pneumoniae types four times during the study period. Our findings point toward the potential role of food as a reservoir for K. pneumoniae in humans.