Detection of a hypermucoviscous Klebsiella pneumoniae co-producing NDM-5 and OXA-48 carbapenemases with sequence type 383, Brescia, Italy

Molecular characterization of hypermucoviscous carbapenemase-encoding Klebsiella pneumoniae isolates from an Egyptian hospital

This study aimed to screen antibiotic resistance and virulence genes in carbapenem-resistant hypermucoviscous Klebsiella pneumoniae isolates from an Egyptian hospital. Among 38 previously confirmed carbapenem-nonsusceptible K. pneumoniae isolates, a string test identified three isolates as positive for hypermucoviscosity. Phenotypic characterization and molecular detection of carbapenemase- and virulence-encoding genes were performed. PCR-based multilocus sequence typing and phylogenetics were used to determine the clonality and global epidemiology of the strains. The coexistence of virulence and resistance genes in the isolates was analyzed statistically using a chi-square test. Three isolates showed the presence of carbapenemase-encoding genes (blaNDM, blaVIM, and blaIMP), adhesion genes (fim-H-1 and mrkD), and siderophore genes (entB); the isolates belonged to sequence types (STs) 101, 1310, and 1626. The relatedness between these sequence types and the sequence types of globally detected hypermucoviscous K. pneumoniae that also harbor carbapenemases was determined. Our analysis showed that the resistance and virulence profiles were not homogenous. Phylogenetically, different clones clustered together. There was no significant association between the presence of resistance and virulence genes in the isolates. There is a need for periodic surveillance of the healthcare settings in Egypt and globally to understand the true epidemiology of carbapenem-resistant, hypermucoviscous K. pneumoniae.

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.

Resistance and virulence features of hypermucoviscous Klebsiella pneumoniae from bloodstream infections: Results of a nationwide Italian surveillance study

Among Enterobacterales, Klebsiella pneumoniae (Kp) is one of the major opportunistic pathogens causing hospital-acquired infections. The most problematic phenomenon linked to Kp is related to the dissemination of multi-drug resistant (MDR) clones producing carbapenem-hydrolyzing enzymes, representing a clinical and public health threat at a global scale. Over the past decades, high-risk MDR clones (e.g., ST512, ST307, ST101 producing bla_KPC–type carbepenemases) have become endemic in several countries, including Italy. Concurrently, the spread of highly virulent Kp lineages (e.g., ST23, ST86) able to cause severe, community-acquired, pyogenic infections with metastatic dissemination in immunocompetent subjects has started to be documented. These clones, designated as hypervirulent Kp (hvKp), produce an extensive array of virulence factors and are highly virulent in previously validated animal models. While the prevalence and distribution of MDR Kp has been previously assessed at local and national level knowledge about dissemination of hvKp remains scarce. In this work, we studied the phenotypic and genotypic features of hypermucoviscous (HMV, as possible marker of increased virulence) Kp isolates from bloodstream infections (BSI), obtained in 2016–17 from 43 Italian Laboratories. Antimicrobial susceptibility testing, whole genome sequencing and the use of two animal models (G. mellonella and murine) were employed to characterize collected isolates. Over 1502 BSI recorded in the study period, a total of 19 Kp were selected for further investigation based on their HMV phenotype. Results showed that hvKp isolates (ST5, ST8, ST11, ST25) are circulating in Italy, although with a low prevalence and in absence of a clonal expansion; convergence of virulence (yersiniabactin and/or salmochelin, aerobactin, regulators of mucoid phenotype) and antimicrobial-resistance (extended-spectrum beta-lactamases) features was observed in some cases. Conventional MDR Kp clones (ST307, ST512) may exhibit an HMV phenotype, but with a low virulence potential in the animal models. To the best of our knowledge, this work represents the first systematic survey on HMV and hvKp in Italy, employing a functional characterization of collected isolates. Future surveillance programs are warranted to monitor the threatening convergence of virulence and resistance among MDR Kp and the spread of hvKp.

Infections caused by hypervirulent Klebsiella pneumoniae in non-endemic countries: three case reports and review of the literature

OBJECTIVES

Spontaneous liver abscess caused by a hypervirulent Klebsiella pneumoniae strain was first described several decades ago in Taiwan and has been an emerging clinical entity worldwide ever since. We aimed to describe the clinical and microbiological characteristics of this infection in a non-endemic setting.

METHODS

A narrative literature review was conducted in PubMed for European case reports of hypervirulent Klebsiella pneumoniae from 2016 to 2021.

RESULTS

Forty case reports were retrieved. Mean age of the patients was 59 years and 72% were male. Diabetes mellitus was present in 33%. Twenty percent of the patients originated from an endemic region. A liver abscess and bacteremia were observed in, respectively, 83% and 80% of the cases. The most frequent metastatic infections were found in the eye (28%) and the lungs (28%). The sensitivity of molecular capsular antigen detection and the string test was 87% and 92%, respectively. Sixty-three percent of the strains had a wildtype resistance.

CONCLUSION

Hypervirulent Klebsiella pneumoniae infections in non-endemic countries are most frequently observed in middle-aged males. Clinicians should be vigilant for metastatic infections.

Emergence of hypermucoviscous colistin-resistant high-risk convergent Klebsiella pneumoniae ST-2096 clone from Pakistan

Klebsiella pneumoniae convergent clones are considered a threat to healthcare settings. Here we report a comprehensive genomic profiling of an emerging colistin-resistant K. pneumoniae ST-2096 convergent clone from Pakistan. Methods: Whole-genome sequencing was performed and raw reads were assembled antimicrobial resistance and virulence genes were predicted using various online tools. Results & conclusion: The phenotypically multidrug-resistant (MDR) and hypermucoviscous (hv) colistin-resistant K. pneumoniae (hvCRKP-10718), which, intriguingly, possessed a wide range of antimicrobial resistance (bla_TEM-1A, bla_OXA-1, bla_OXA-232, bla_CTX-M-15, bla_SHV-106, oqxA, oqxB, aac(6')-Ib-cr, aadA2, aac(6')-Ib-cr, armA, tetD, mphE, msrE, fosA, dfrA1, dfrA12, dfrA14, catB3, sul1) and virulence determinants (RmpA/RmpA2, yersiniabactin [ybt], aerobactin [iuc/iut], enterobactin). Furthermore, the acquisition of various mobile genetic elements (MDR/virulent plasmids, type II integron gene cassette, insertional sequences, transposases) and associated hv capsular type made this MDR/hv isolate a convergent clone belonging to a high-risk lineage (ST-2096). Based on core-genome multilocus sequence typing and single-nucleotide polymorphism analysis, this isolate showed ≥99% nucleotide identity with MDR K. pneumoniae isolates from India, depicting its evolutionary background. This study provides a comprehensive genomic profiling of this high-risk convergent K. pneumoniae ST-2096 clone from Pakistan. Comparative genomics of MDR/hv colistin-resistant K. pneumoniae isolates with other MDR convergent strains from the Indian subcontinent indicated the emergence of this evolving superbug.

Genomic characterization of Escherichia coli isolates co-producing NDM-5 and OXA-1 from hospitalized patients with invasive infections

OBJECTIVES

Carbapenems are one of the latest therapeutic choices to treat infections due to multi-drug resistant microorganisms. For this reason, the spread of carbapenemase producing Enterobacteriaceae represents a serious health public problem. In this study, we describe isolates co-producing bla_NDM-5 and bla_OXA-1 METHODS: Three Escherichia coli isolates obtained from patients with invasive infection were analysed by phenotypic antibiotic susceptibility and whole genome sequencing (WGS).

RESULTS

All the isolates were resistant to carbapenems, most beta-lactam antibiotics, piperacillin-tazobactam, amoxicillin/clavulanic acid and ciprofloxacin, remaining susceptible to amikacin, fosfomycin, colistin and tigecycline. The isolates belonged to ST-44, ST-405 and ST-167 and co-harboured the bla_NDM-5 and bla_OXA-1 genes. Two of them harboured also some ESBL genes (bla_CTX-M-15 and bla_TEM-1b). bla_NDM5 gene was probably carried chromosomally even if different plasmids were identified. Different virulence genes were also identified.

CONCLUSIONS

Our results highlight that continuous surveillance is essential to monitor the spread of clinically important multidrug resistant pathogens.

A global perspective on the convergence of hypervirulence and carbapenem resistance in Klebsiella pneumoniae

Hypervirulence and carbapenem resistance have emerged as two distinct evolutionary directions for Klebsiella pneumoniae, which pose a great threat in clinical settings. Multiple virulence factors contribute to hypervirulence, and the mechanisms of carbapenem resistance are complicated. However, more and more K. pneumoniae strains have been identified in recent years integrating both phenotypes, resulting in devastating clinical outcomes. Hypervirulent and carbapenem-resistant K. pneumoniae (CR-hvKP) emerged in the early 2010s and thereafter have become increasingly prevalent. CR-hvKP are primarily prevalent in Asia, especially China, but are reported all over the world. Mechanisms for the emergence of CR-hvKP can be summarised by three patterns: (i) carbapenem-resistant K. pneumoniae (CRKP) acquiring a hypervirulent phenotype; (ii) hypervirulent K. pneumoniae (hvKP) acquiring a carbapenem-resistant phenotype; and (iii) K. pneumoniae acquiring both a carbapenem resistance and hypervirulence hybrid plasmid. With their global dissemination, continued surveillance of the emergence of CR-hvKP should be more highly prioritised.