Hypervirulent Klebsiella pneumoniae Infections in Pediatric Populations in Beijing (2017-2019): Clinical Characteristics, Molecular Epidemiology and Antimicrobial Susceptibility

Antibiotic resistance rates in hypervirulent Klebsiella pneumoniae strains: A systematic review and meta-analysis

OBJECTIVES

In response to the growing global concerns regarding antibiotic resistance, we conducted a meta-analysis to assess the prevalence of antibiotic resistance in hypervirulent Klebsiella pneumoniae (hvKp) strains.

METHODS

We conducted a meta-analysis of antibiotic resistance in the hvKp strains. Eligible studies published in English until April 10, 2023, were identified through a systematic search of various databases. After removing duplicates, two authors independently assessed and analysed the relevant publications, and a third author resolved any discrepancies. Data extraction included publication details and key information on antibiotic resistance. Data synthesis employed a random-effects model to account for heterogeneity, and various statistical analyses were conducted using R and the metafor package.

RESULTS

This meta-analysis of 77 studies from 17 countries revealed the prevalence of antibiotic resistance in hvKp strains. A high resistance rates have been observed against various classes of antibiotics. Ampicillin-sulbactam faced 45.3% resistance, respectively, rendering them largely ineffective. The first-generation cephalosporin cefazolin exhibited a resistance rate of 38.1%, whereas second-generation cefuroxime displayed 26.7% resistance. Third-generation cephalosporins, cefotaxime (65.8%) and ceftazidime (57.1%), and fourth-generation cephalosporins, cefepime (51.3%), showed substantial resistance. The last resort carbapenems, imipenem (45.7%), meropenem (51.0%) and ertapenem (40.6%), were not spared.

CONCLUSION

This study emphasizes the growing issue of antibiotic resistance in hvKp strains, with notable resistance to both older and newer antibiotics, increasing resistance over time, regional disparities and methodological variations. Effective responses should involve international cooperation, standardized testing and tailored regional interventions.

Pyogenic liver abscess in pediatric populations in beijing (2008-2023)

BACKGROUND

Data on pyogenic liver abscess (PLA) of children in China have been limited. We aimed to summarize the clinical feather, microbiological characteristics, management, and outcome of PLA in children.

METHOD

We retrospectively reviewed PLA cases from January 2008 to June 2023 at Beijing Children's Hospital. Clinical characteristics, pathogens and management were analyzed.

RESULTS

We diagnosed 57 PLA patients in our center. The median onset age was 4.5 years and the male-to-female ratio was 1.6:1. The median diagnostic time was nine days and the median length of stay was 22 days. Twenty-eight patients (49.1%) had predisposing factors, around 71.4% of the patients had malignant hematology and primary immunodeficiency disease. Patients with underlying factors were more likely to have extrahepatic organ involvement (p = 0.024), anemia (p < 0.001), single abscess (p = 0.042), unilateral involvement (p = 0.039), and small size of the abscess (p = 0.008). Twenty-four patients (42.1%) had extrahepatic organ involvement. Pathogens were identified in 17 patients (29.8%), the most common pathogens were Klebsiella pneumoniae and Staphylococcus aureus. The positive rate of metagenomic next-generation sequencing (mNGS) was 87.5% (7/8). On multivariable analysis, the extrahepatic organ involved (p = 0.029) and hepatomegaly (p = 0.025) were two independent factors associated with poor outcomes.

CONCLUSIONS

PLA is usually seen in children with predisposing factors. Malignant hematology and primary immunodeficiency disease were the most common underlying diseases. Extrahepatic organ involvement and hepatomegaly are associated with poor prognosis. Increased use of mNGS could be beneficial for identifying pathogens.

The overlap of accessory virulence factors and multidrug resistance among clinical and surveillance Klebsiella pneumoniae isolates from a neonatal intensive care unit in Nepal: a single-centre experience in a resource-limited setting

BACKGROUND

There is a lack of data on the characteristics of overlap between acquired antimicrobial resistance and virulence factors in Klebsiella pneumoniae in high-risk settings, especially with the inclusion of surveillance isolates along with the clinical. We investigated K. pneumoniae isolates, from a neonatal intensive care unit (NICU) in Nepal, for the presence of both accessory virulence factors and acquired antimicrobial resistance.

METHODS

Thirty-eight clinical and nineteen surveillance K. pneumoniae isolates obtained between January 2017 and August 2022 in the NICU of Siddhi Memorial Hospital, Bhaktapur, Nepal were investigated with antimicrobial susceptibility testing, PCR-based detection of β-lactamases and virulence factors, and genetic similarity by ERIC-PCR.

RESULTS

K. pneumoniae was found positive in 37/85 (43.5%) blood culture-positive neonatal bloodstream infections, 34/954 (3.6%) patient surveillance cultures, and 15/451 (3.3%) environmental surveillance samples. Among 57 isolates analyzed in this study, we detected multidrug resistance in 37/57 (64.9%), which was combined with at least one accessory virulence factor in 21/37 (56.8%). This overlap was mostly among β-lactamase producing isolates with accessory mechanisms of iron acquisition. These isolates displayed heterogenous ERIC-PCR patterns suggesting genetic diversity.

CONCLUSIONS

The clinical significance of this overlap between acquired antimicrobial resistance and accessory virulence genes in K. pneumoniae needs further investigation. Better resource allocation is necessary to strengthen infection prevention and control interventions in resource-limited settings.

Genomic and clinical characterization of Klebsiella pneumoniae carrying the pks island

Background

The pks island and its production of the bacterial secondary metabolite genotoxin, colibactin, have attracted increasing attention. However, genomic articles focusing on pks islands in Klebsiella pneumoniae, as well as comparative genomic studies of mobile genetic elements, such as prophages, plasmids, and insertion sequences, are lacking. In this study, a large-scale analysis was conducted to understand the prevalence and evolution of pks islands, differences in mobile genetic elements between pks-negative and pks-positive K. pneumoniae, and clinical characteristics of infection caused by pks-positive K. pneumoniae.

Methods

The genomes of 2,709 K. pneumoniae were downloaded from public databases, among which, 1,422 were from NCBI and 1,287 were from the China National GeneBank DataBase (CNGBdb). Screening for virulence and resistance genes, phylogenetic tree construction, and pan-genome analysis were performed. Differences in mobile genetic elements between pks-positive and pks-negative strains were compared. The clinical characteristics of 157 pks-positive and 157 pks-negative K. pneumoniae infected patients were investigated.

Results

Of 2,709 K. pneumoniae genomes, 245 pks-positive genomes were screened. The four siderophores, type VI secretion system, and nutritional factor genes were present in at least 77.9% (191/245), 66.9% (164/245), and 63.3% (155/245) of pks-positive strains, respectively. The number and fragment length of prophage were lower in pks-positive strains than in pks-negative strains (p < 0.05). The prevalence of the IS6 family was higher in pks-negative strains than in pks-positive strains, and the prevalence of multiple plasmid replicon types differed between the pks-positive and pks-negative strains (p < 0.05). The detection rate of pks-positive K. pneumoniae in abscess samples was higher than that of pks-negative K. pneumoniae (p < 0.05).

Conclusion

The pks-positive strains had abundant virulence genes. There were differences in the distribution of mobile genetic elements between pks-positive and pks-negative isolates. Further analysis of the evolutionary pattern of pks island and epidemiological surveillance in different populations are needed.

Pediatric brain abscess with fatal outcome caused by hypervirulent Klebsiella pneumoniae, serotype K2-ST65

Hypervirulent Klebsiella pneumoniae (hvKp) is an emerging pathotype in addition to classical Klebsiella pneumoniae, with its ability to cause life-threatening, community-acquired metastatic infections even in healthy individuals. We presented a case of cerebral abscess preceded by otitis media in a 10-year-old child caused by hvKp. The isolates from blood pus aspirate were later identified as K. pneumoniae capsular serotype K2 and closely related to sequence type (ST65), with multiple hypervirulent genes detected (rmpA, rmpA2, iucA and peg344). She succumbed to death despite surgical drainage and susceptible antibiotic therapy. Clinicians should be cognizant of the rising incidence of hvKp infections in pediatric populations.

Clinical and genomic analysis of hypermucoviscous Klebsiella pneumoniae isolates: Identification of new hypermucoviscosity associated genes

Introduction

Hypermucoviscous Klebsiella pneumoniae (HmKp) poses an emerging and highly pathogenic global health threat. This study aimed to investigate the clinical and genomic characteristics of HmKp isolates to better understand the virulence mechanisms of the hypermucoviscous (HMV) phenotype.

Methods

From May 2018 to August 2021, 203 non-repeat K. pneumoniae isolates causing invasive infections were collected from a hospital in Beijing, China. Isolates were divided into HmKp (n=90, 44.3%) and non-HmKp (n=113, 55.7%) groups according to string test results.

Results

Multivariate regression showed that diabetes mellitus (odds ratio [OR]=2.20, 95% confidence interval (CI): 1.20-4.05, p=0.010) and liver abscess (OR=2.93, CI 95%:1.29-7.03, p=0.012) were associated with HmKp infections. K. pneumoniae was highly diverse, comprising 87 sequence types (STs) and 54 serotypes. Among HmKp isolates, ST23 was the most frequent ST (25/90, 27.8%), and the most prevalent serotypes were KL2 (31/90, 34.4%) and KL1 (27/90, 30.0%). Thirteen virulence genes were located on the capsular polysaccharide synthesis region of KL1 strains. HmKp isolates were sensitive to multiple antibiotics but carried more SHV-type extended spectrum β-lactamase (ESBL) resistance genes (p<0.05), suggesting that the emergence of ESBL-mediated multidrug resistance in HmKp should be monitored carefully during treatment. Phylogenetic analysis disclosed that HmKp isolates were highly diverse. Comparative genomic analysis confirmed that the HMV phenotype is a plasmid-encoded virulence factor. Seventeen HmKp genes were highly associated with HmKp, and included rmpAC, 7 iron-acquisition-related genes, and pagO, which may promote liver abscess formation.

Discussion

This investigation provides insight into the mechanisms producing the HMV phenotype.

Epidemiological characteristics and molecular evolution mechanisms of carbapenem-resistant hypervirulent Klebsiella pneumoniae

Carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP), a type of Klebsiella pneumoniae (KP) that exhibits hypervirulence and carbapenem resistance phenotypes, can cause severe infections, both hospital- and community-acquired infections. CR-hvKP has brought great challenges to global public health and is associated with significant morbidity and mortality. There are many mechanisms responsible for the evolution of the hypervirulence and carbapenem resistance phenotypes, such as the horizontal transfer of the plasmid carrying the carbapenem resistance gene to hypervirulent Klebsiella pneumoniae (hvKP) or carbapenemase-producing Klebsiella pneumoniae (CRKP) acquiring a hypervirulence plasmid carrying a virulence-encoding gene. Notably, KP can evolve into CR-hvKP by acquiring a hybrid plasmid carrying both the carbapenem resistance and hypervirulence genes. In this review, we summarize the evolutionary mechanisms of resistance and plasmid-borne virulence as well as the prevalence of CR-hvKP.

The Molecular Epidemiology of Prevalent Klebsiella pneumoniae Strains and Humoral Antibody Responses against Carbapenem-Resistant K. pneumoniae Infections among Pediatric Patients in Shanghai

Carbapenem-resistant Klebsiella pneumoniae (CRKP) has caused wide dissemination among pediatric patients globally and thus has aroused public concern. Here, we investigated the clinical epidemiological characteristics of 140 nonreplicate clinical K. pneumoniae strains isolated from pediatric patients between January and December 2021. Of all isolates, 16.43% (23 of 140) were CRKP strains, which predominantly contained KPC carbapenemase. wzi sequencing demonstrated that KL47 (65.22%, 15 of 23) was the most frequent capsular type, followed by KL64 (17.39%, 4 of 23). A total of 23 CRKP strains were classified into three different O-genotypes, including OL101 (65.22%, 15 of 23), O1 (26.09%, 6 of 23), and O3 (8.7%, 2 of 23). Interestingly, KL47 strains were strongly associated with OL101, while KL64 strains were all linked with O1. Some capsule-deficient strains were identified by serological typing, phage-typing, depolymerase-typing, and uronic acid assay. In this study, compared with healthy children, higher titers of anti-capsular polysaccharides (CPS) IgG were first detected in the sera of K47 and K64 K. pneumoniae-infected children, which had the effective bactericidal activity against corresponding serotype K. pneumoniae strains. These findings will facilitate the development of novel therapeutic and vaccine strategies against K. pneumoniae infection in children.

IMPORTANCE The emergence of carbapenem-resistant Klebsiella pneumoniae (CRKP) strains resistant to numerous antibiotics and the limited therapeutic options available have become an urgent health threat to the immunocompromised pediatric population. Vaccines and antibodies, especially those targeting capsular polysaccharides, may be novel and effective prevention and treatment options. Thus, it is important to understand the spread of CRKP in pediatric populations. This research presents OL101:KL47 and O1:KL64 as the predominant combinations among CRKP strains in children in Shanghai, China. The primary carbapenemase gene is KPC in CRKP strains. Additionally, this study found elevated levels of anti-CPS IgG against K47 and K64 K. pneumoniae strains in pediatric patients for the first time. The significant bactericidal activity of these anti-CPS IgGs was confirmed.

Nosocomial dissemination of hypervirulent Klebsiella pneumoniae with high-risk clones among children in Shanghai

Objectives

Although hypervirulent Klebsiella pneumoniae (hvKp) is an increasing public health problem, there remains limited epidemiological information regarding hvKp infections in children. Here, we conducted a clinical, molecular and phenotypic surveillance of hvKp strains in a pediatric population.

Methods

Non-repetitive K. pneumoniae (Kp) strains consecutively collected during 2019-2020 were screened for hypervirulence genes (prmpA, prmpA2, iucA, iroB, and peg344) using PCR. Positive strains were further characterized by four phenotypic assays (string test, serum killing assay, siderophore production, Galleria mellonella lethality assay), followed by murine sepsis model to determine virulence in vitro and in vivo. Also, capsular types, sequence types, plasmid replicon types, antimicrobial resistance determinants and susceptibility were analyzed.

Results

A total of 352 isolates were collected, wherein 83 (23.6%) were hypervirulence genes-positive Kp (hgKp). A significant increase in KPC-2-producing KL47-ST11 among hgKp strains was observed, from 5.3% (1/19) in 2019 to 67.6% (25/37) in 2020 (P<.0001), suggesting the potential dissemination of the hybrid virulence and carbapenem-resistance encoding plasmid among children. Further, hgKp isolates were classified into hvKp (n = 27) and hgKp-low virulence (hgKp-Lv) (n = 56) based on virulence phenotypic assays. In hvKp, diverse genetic clones were observed and K1-ST23 or K2-ST25 strains with sensitivity to multiple antibiotics were prevalent (25.9%, 7/27). Compared with hgKp-Lv, hvKp infection had a higher propensity to involve severe pneumonia (22.2% vs. 12.5%) in elder children and significant higher mortality in mice (P = 0.0086). Additionally, either hvKp or hgKp-Lv infections were mostly healthcare-associated and hospital-acquired (74.1% vs. 91.9%).

Conclusions

These data suggest that K1-ST23 and K2-ST25 are high-risk clones of hvKp, and the genetic convergence of virulence and carbapenem-resistance is increasing among children. Control measures are needed to prevent the dissemination in clinical settings.

Development and validation of a prediction model based on clinical and CT features for invasiveness of K. pneumoniae liver abscess

OBJECTIVES

Klebsiella pneumoniae liver abscess (KPLA) complicated with extrahepatic migratory infection (EMI) is defined as invasive KPLA. The current study aimed to develop and validate a risk prediction model for the invasiveness of KPLA.

METHODS

From 2010 to 2020, KPLA patients from four institutes were selected retrospectively. In the development cohort, risk factors from a logistic regression analysis were utilized to develop the prediction model. External validation was performed using an independent cohort.

RESULTS

A total of 382 KPLA patients comprised two separate cohorts: development cohort (institute 1, n = 286) and validation cohort (institute 2-4, n = 86). The overall incidence of EMI was 19.1% (development cohort, n = 55; validation cohort, n = 18, p > 0.05). In the development cohort, four risk factors (age ≤ 40 years, fasting blood glucose (FBG) > 7 mmol/L, no rim enhancement, and thrombophlebitis on CT), significantly associated with EMI, were incorporated into the scoring system. The area under curve (AUC) of the receiver operating characteristic curve (ROC) in the development and validation cohorts was 0.931 (95% confidence interval [CI]: 0.93-0.95) and 0.831 (95% CI: 0.86-0.91), respectively. The calibration curves fitted well. The incidence of EMI was 3.3% and 56.5% for the low- (total scores ≤ 4) and high-risk (total scores > 4) groups in the development cohort, and 3.2% and 66.7% in the validation cohort (all p < 0.001), respectively.

CONCLUSIONS

Age ≤ 40 years, FBG > 7 mmol/L, no rim enhancement, and thrombophlebitis were independent risk factors for EMI. This validated prediction model may aid clinicians in identifying KPLA patients at increased risk for invasiveness.

KEY POINTS

• Four risk factors are significantly associated with extrahepatic migratory infections (EMI): age ≤ 40 years, fasting blood glucose (FBG) > 7 mmol/L, no rim enhancement, and thrombophlebitis on CT. • Based on these risk factors, the current study developed and validated a prediction model for the invasiveness of Klebsiella pneumoniae liver abscess (KPLA). • This validated prediction model may in the help early identification of KPLA patients at increased risk for invasiveness.