Community-acquired meningitis caused by a CG86 hypervirulent Klebsiella pneumoniae strain: first case report in the Caribbean

Otitis Media Progressing to Community-Acquired Meningitis in Diabetic Patients: A Case Report of K2-ST375 hypervirulent Klebsiella pneumoniae and Literature Review

Community-acquired Klebsiella pneumoniae meningitis (CA-KPM) can rapidly progress to invasive infection in healthy individuals. We present the case of a 54-year-old man with a history of acute suppurative otitis media and uncontrolled type 2 diabetes mellitus (T2DM), who had been treated with oral antibiotics intermittently and irregularly for one month. His symptoms did not improve and continued to worsen, leading to fever and coma. Metagenomic next-generation sequencing (mNGS) of cerebrospinal fluid (CSF) identified Klebsiella pneumoniae (KP) after 24 hours in the intensive care unit (ICU). Subsequent CSF culture confirmed a hypervirulent KP (hvKp) strain with capsular genotype K2 and sequence type (ST) 375. Fortunately, the patient made a full recovery with targeted antimicrobial therapy and was discharged. Despite the delayed diagnosis, the outcome was favorable. This case highlights the importance of clinicians, particularly otolaryngologists, maintaining a high index of suspicion for CA-KPM in patients with both otitis media and T2DM, emphasizing the need for timely multidisciplinary consultation.

Clinical and laboratory insights into the threat of hypervirulent Klebsiella pneumoniae

Hypervirulent Klebsiella pneumoniae (hvKP) typically causes severe invasive infections affecting multiple sites in healthy individuals. In the past, hvKP was characterized by a hypermucoviscosity phenotype, susceptibility to antimicrobial agents, and its tendency to cause invasive infections in healthy individuals within the community. However, there has been an alarming increase in reports of multidrug-resistant hvKP, particularly carbapenem-resistant strains, causing nosocomial infections in critically ill or immunocompromised patients. This presents a significant challenge for clinical treatment. Early identification of hvKP is crucial for timely infection control. Notably, identifying hvKP has become confusing due to its prevalence in nosocomial settings and the limited predictive specificity of the hypermucoviscosity phenotype. Novel virulence predictors for hvKP have been discovered through animal models or machine learning algorithms, while standardization of identification criteria is still necessary. Timely source control and antibiotic therapy have been widely employed for the treatment of hvKP infections. Additionally, phage therapy is a promising alternative approach due to escalating antibiotic resistance. In summary, this narrative review highlights the latest research progress in the development, virulence factors, identification, epidemiology of hvKP, and treatment options available for hvKP infection.

Global spread and evolutionary convergence of multidrug-resistant and hypervirulent Klebsiella pneumoniae high-risk clones

For people living in developed countries life span is growing at a faster pace than ever. One of the main reasons for such success is attributable to the introduction and extensive use in the clinical practice of antibiotics over the course of the last seven decades. In hospital settings, Klebsiella pneumoniae represents a well-known and commonly described opportunistic pathogen, typically characterized by resistance to several antibiotic classes. On the other hand, the broad wedge of population living in Low and/or Middle Income Countries is increasing rapidly, allowing the spread of several commensal bacteria which are transmitted via human contact. Community transmission has been the original milieu of K. pneumoniae isolates characterized by an outstanding virulence (hypervirulent). These two characteristics, also defined as "pathotypes", originally emerged as different pathways in the evolutionary history of K. pneumoniae. For a long time, the Sequence Type (ST), which is defined by the combination of alleles of the 7 housekeeping genes of the Multi-Locus Sequence Typing, has been a reliable marker of the pathotype: multidrug-resistant clones (e.g. ST258, ST147, ST101) in the Western world and hypervirulent clones (e.g. ST23, ST65, ST86) in the Eastern. Currently, the boundaries separating the two pathotypes are fading away due to several factors, and we are witnessing a worrisome convergence in certain high-risk clones. Here we review the evidence available on confluence of multidrug-resistance and hypervirulence in specific K. pneumoniae clones.

Clinical Spectrum and Outcomes of Cryptogenic Klebsiella pneumoniae Liver Abscess in the Americas: A Scoping Review

(1) Background: Cryptogenic Klebsiella pneumoniae liver abscesses are an invasive infection with or without extra hepatic involvement in the absence of hepatobiliary disease or abdominal malignancy. Most of the evidence has emanated from reports from Asia, and previous studies in the Americas have limited clinical characterization. (2) Methods: To understand this syndrome's characteristics on our continent, we conducted a scoping review to identify adult cases of idiopathic, community-acquired monomicrobial K. pneumoniae liver abscess in the Americas. (3) Results: We identified 144 cases spanning 1978-2022. Most cases were reported in males that had traveled or migrated from Southeast or East Asia with diabetes mellitus. Extrahepatic involvement and bacteremia were common, including seeding to the lungs, ocular structures, and central nervous system. Although limited by sample size, the most commonly reported genes were magA or rmpA. Concomitant percutaneous drainage and third generation cephalosporins (alone or in combination with other antibiotics) were frequently used, yet pooled fatality occurred in 9% of the reported cases. (4) Conclusions: The features of cryptogenic K. pneumoniae liver abscess in the Americas mirror those described in Asia, confirming its global dissemination. This condition is increasingly being reported in our continent and carries significant clinical impact due to its systemic invasiveness.

Reporting on antibiotic use patterns using the WHO Access, Watch, Reserve classification in the Caribbean

Objective

To assess antibiotic use in three hospitals in three Caribbean countries based on data from 2013 and 2018 using the World Health Organization Essential Medicines List "Access, Watch, Reserve" (AWaRe) classification.

Methods

A retrospective observational study, which analyzed the World Health Organization Point Prevalence Survey data from three hospitals in three Caribbean countries, to examine proportional AWaRe group antibiotic use for the top ten inpatient indications. The Access-to-Watch ratio was calculated, and the top three antibiotics prescribed in each hospital were determined.

Results

The final data set included 376 prescriptions for the top ten indications in 766 inpatients. The hospital antibiotic use point prevalence for Hospital 1 was 35.6%, Hospital 2 was 48.6%, and Hospital 3 was 47.1%. The Access-to-Watch ratio for the top ten indications was 2.45, 1.36, and 1.72 in the three hospitals. Access group prevalence was 71.0% in Hospital 1, 57.6% in Hospital 2, and 63.2% in Hospital 3. There were no Reserve antibiotics prescribed in any of the institutions. The most common indication for Watch prescription was skin and soft tissue infections in Hospital 1 and pneumonia in Hospital 2 and 3.

Conclusions

This study draws urgent attention to evidence of a high proportion of Watch antibiotic prescribing and lack of Reserve group antibiotics in three Caribbean countries. This research provides data that may inform national formulary and antimicrobial stewardship policy-making across the settings analyzed and the wider region.

Successful treatment of acute respiratory distress syndrome caused by hypervirulent Klebsiella pneumoniae with extracorporeal membrane oxygenation and continuous renal replacement therapy: A case report and literature review

Hypervirulent Klebsiella pneumoniae (hvKP) causes invasive infections and leads to high morbidity and mortality rates. Here, we report the case of a Chinese man with diabetes mellitus who developed acute respiratory distress syndrome and septic shock due to hvKP belonging to the K1 strain. The patient was treated with venovenous extracorporeal membrane oxygenation and continuous renal replacement therapy, in combination with antibiotics and recovered well. Clinicians should be aware of fatal infections caused by hvKP and investigate the best treatment options for patients at various stages of infection.

Characterization of Beta-Lactam Resistance Genes and Virulence Factors Associated with Multidrug-Resistant Klebsiella pneumoniae Isolated from Patients at Major Hospitals in Trinidad, West Indies

Accurate species identification and antibiotic resistance profiling are essential for the effective management of infections caused by bacterial pathogens. In this study, 373 clinical isolates of K. pneumoniae from major hospitals in Trinidad, West Indies, were characterized for resistance against beta-lactam antibiotics and the presence of genes encoding important virulence factors. Most of the isolates showed extended spectrum β-lactamase (ESBL) activity but few also displayed carbapenemase or 'ESBL + carbapenemase' activities. Polymerase chain reaction analysis revealed the presence of genes for ESBL subtypes bla_TEM, bla_SHV, and bla_CTX-M that were dominant in isolates with the ESBL phenotype as well as those that did not show ESBL or carbapenemase activities. The carbapenem resistance gene, bla_KPC, and the metallo-β-lactamase (MBL) gene, bla_NDM-1, were also detected in some of the isolates. Multiple virulence genes were also detected, but the fimH-uge was the most common combination found among the local isolates. The findings of this study represent the first comprehensive study on the prevalence of ESBL, KPC and MBL genes and virulence profiling in antibiotic-resistant K. pneumoniae in Trinidad. Furthermore, the occurrence of multiple resistant phenotypes and gene combinations were revealed, though at low prevalence rates. This work emphasizes the need to implement molecular-based techniques in diagnostic workflows for rapid and accurate species identification and profiling of resistance and virulence genes in K. pneumoniae in Trinidad and Tobago.

A Rare Case of Third Generation Cephalosporin-Resistant Klebsiella Meningitis

Acute bacterial meningitis is one of the very common and severe forms of central nervous system (CNS) infection worldwide in almost all age groups. It remains a common cause of mortality, especially in underdeveloped countries, if not treated timely. Detecting an organism from the CSF culture is crucial in the management of acute bacterial meningitis. Selection of antibiotics according to the culture are a very important part of the management. Most commonly involved organisms include Streptococcus pneumoniae, Neisseria meningitides, and Listeria monocytogenes, while other organisms are very uncommon. Here, we report a rare case of Klebsiella pneumoniae meningitis in a young female, which was found resistant to multiple antibiotics including third generation of cephalosporin.

Characterization of hypervirulent Klebsiella pneumoniae isolates in Belgium

Hypervirulent Klebsiella pneumoniae (hvKp) raised concern worldwide. We studied 22 hvKp clinical invasive isolates referred to the Belgian national reference laboratory between 2014 and 2020. Sixty-four percent of the isolates expressed K2 capsular serotype and belonged to 7 different MLST lineages, while 32% expressed K1 (all belonging to ST23) and were associated with liver abscesses. Primary extra-hepatic infections were reported in 36% and sepsis for 95% of the patients with 30% of deaths. Improved clinical and microbiological diagnostics are required as hvKp may represent an underestimated cause of community-acquired invasive infections in Belgium.

Antimicrobial Susceptibility, Virulence, and Genomic Features of a Hypervirulent Serotype K2, ST65 Klebsiella pneumoniae Causing Meningitis in Italy

The rise of a new hypervirulent variant of Klebsiella pneumoniae (hvKp) was recently reported, mainly linked to the ST23 lineage. The hvKp variants can cause severe infections, including hepatic abscesses, bacteremia, and meningitis, with a particularly disconcerting propensity to cause community-acquired, life-threatening infection among young and otherwise healthy individuals. The present study aimed to report the clinical characteristics of a hypermucoviscous K. pneumoniae strain isolated in Italy and sustaining recurrent meningitis in a patient of Peruvian origin. A further objective was to retrospectively investigate, by means of whole-genome sequencing (WGS) analysis, the genomic features of such an isolate. The hypermucoviscosity phenotype of the strain (sk205y205t) was determined using the string test. Genomic information was obtained by WGS (Illumina) and bioinformatic analysis. Strain sk205y205t was susceptible to most antibiotics, despite the presence of some resistance genes, including bla_SHV-11, bla_SHV-67, fosA, and acrR. The isolate belonged to ST65 and serotype K2, and exhibited several virulence factors related to the hvKp variant. Among these, were the siderophore genes entB, irp2, iroN, iroB, and iucA; the capsule-regulating genes rmpA and rmpA2; and the type 1 and 3 fimbriae fimH27 and mrkD, respectively. A further operon, encoding the genotoxin colibactin (clbA-Q), was also identified. The virulence plasmids pK2044, pRJA166b, and pNDM. MAR were also detected. Phylogenetic investigation showed that this Italian strain is highly similar to a Chinese isolate, suggesting a hidden circulation of this hvKp ST65 K2 lineage.

One Health Genomic Study of Human and Animal Klebsiella pneumoniae Isolated at Diagnostic Laboratories on a Small Caribbean Island

Klebsiella pneumoniae causes a variety of infections in both humans and animals. In this study, we characterised the genomes of human and animal isolates from two diagnostic laboratories on St. Kitts, a small Caribbean island inhabited by a large population of vervet monkeys. In view of the increased chances of direct or indirect contact with humans and other animal species, we used the One Health approach to assess transmission of K. pneumoniae across host species by sequencing 82 presumptive K. pneumoniae clinical isolates from humans (n = 51), vervets (n = 21), horses (n = 5), dogs (n = 4) and a cat (n = 1). Whole genome sequencing (WGS) was carried out using Illumina technology. De novo assembly was performed in CLC Genomics Workbench v.11.0. Single nucleotide polymorphisms were detected using NASP followed by phylogenetic analysis using IQ-TREE. Virulence and antimicrobial resistance gene contents were analysed using the Kleborate and CGE pipelines. WGS-based analysis showed that 72 isolates were K. pneumoniae sensu stricto and five K. quasipneumoniae and five K. variicola. K. pneumoniae isolates belonged to 35 sequence types (ST), three of which were occasionally shared between humans and animals: ST23, ST37 and ST307. The ST23 strains from vervets formed a separate cluster amongst publicly available sequenced ST23 strains, indicating the presence of a specific vervet sublineage. Animal strains harbored fewer resistance genes and displayed distinct virulence traits that appeared to be host-specific in vervet isolates. Our results show that K. pneumoniae infections on this Caribbean island are usually caused by host-specific lineages.

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.

Core Genome Allelic Profiles of Clinical Klebsiella pneumoniae Strains Using a Random Forest Algorithm Based on Multilocus Sequence Typing Scheme for Hypervirulence Analysis

BACKGROUND

Hypervirulent Klebsiella pneumoniae (hvKP) infections can have high morbidity and mortality rates owing to their invasiveness and virulence. However, there are no effective tools or biomarkers to discriminate between hvKP and nonhypervirulent K. pneumoniae (nhvKP) strains. We aimed to use a random forest algorithm to predict hvKP based on core-genome data.

METHODS

In total, 272 K. pneumoniae strains were collected from 20 tertiary hospitals in China and divided into hvKP and nhvKP groups according to clinical criteria. Clinical data comparisons, whole-genome sequencing, virulence profile analysis, and core genome multilocus sequence typing (cgMLST) were performed. We then established a random forest predictive model based on the cgMLST scheme to prospectively identify hvKP. The random forest is an ensemble learning method that generates multiple decision trees during the training process and each decision tree will output its own prediction results corresponding to the input. The predictive ability of the model was assessed by means of area under the receiver operating characteristic curve.

RESULTS

Patients in the hvKP group were younger than those in the nhvKP group (median age, 58.0 and 68.0 years, respectively; P < .001). More patients in the hvKP group had underlying diabetes mellitus (43.1% vs 20.1%; P < .001). Clinically, carbapenem-resistant K. pneumoniae was less common in the hvKP group (4.1% vs 63.8%; P < .001), whereas the K1/K2 serotype, sequence type (ST) 23, and positive string tests were significantly higher in the hvKP group. A cgMLST-based minimal spanning tree revealed that hvKP strains were scattered sporadically within nhvKP clusters. ST23 showed greater genome diversification than did ST11, according to cgMLST-based allelic differences. Primary virulence factors (rmpA, iucA, positive string test result, and the presence of virulence plasmid pLVPK) were poor predictors of the hypervirulence phenotype. The random forest model based on the core genome allelic profile presented excellent predictive power, both in the training and validating sets (area under receiver operating characteristic curve, 0.987 and 0.999 in the training and validating sets, respectively).

CONCLUSIONS

A random forest algorithm predictive model based on the core genome allelic profiles of K. pneumoniae was accurate to identify the hypervirulent isolates.

Genome-Based Analysis of a Sequence Type 1049 Hypervirulent Klebsiella pneumoniae Causing Bacteremic Neck Abscess

Hypervirulent Klebsiella pneumoniae (hvKP) has raised grave concerns in recent years and can cause severe infections with diverse anatomic locations including liver abscess, meningitis, and endophthalmitis. However, there is limited data about neck abscess caused by hvKP. A K. pneumoniae strain Kp_whw was isolated from neck abscess. We characterized the genetic background, virulence determinates of the strain by genomic analysis and dertermined the virulence level by serum resistance assay. Kp_whw belonged to sequence type (ST) 1049 K locus (KL) 5. Kp_whw showed hypermucoviscosity phenotype and was resistant to ampicillin but susceptible to the majority of the other antimicrobial agents. A pLVPK-like virulence plasmid and a chromosomal ICEKp5-like mobile genetic element were carried by Kp_whw, resulting in the risk of dissemination of hypervirulence. The strain exhibited relative higher level of core genome allelic diversity than accessory genome profile, in comparison to hvKP of K1/K2 serotype. Kp_whw was finally demonstrated as virulent as the ST23 K1 serotype hvKP strain NTUH-K2044 in vitro. In conclusion, this work elaborates the genetic background of a clinical hvKP strain with an uncommon ST, reinforcing our understanding of virulence mechanisms of hvKP.

Klebsiella pneumoniae-related invasive liver abscess syndrome complicated by purulent meningitis: a review of the literature and description of three cases

Background

Klebsiella pneumoniae (K. pneumoniae) invasive liver abscess syndrome (ILAS) with purulent meningitis was rarely identified the mainland of China. Last winter, we received 3 cases of K. pneumoniae meningitis and all of them died in a short time. We report these cases in order to find the reason of high mortality and discuss effective effort to improve these patients’ prognosis.

Case presentation

Three patients with uncontrolled diabetes developed live abscess and purulent meningitis. Upon admission, the clinical manifestations, laboratory result of blood and cerebrospinal fluid (CSF) and imaging examinations were compatible with K. pneumoniae ILAS which had metastasis infection of meningitis. Even with timely adequate antibiotic therapy and strict glycemic control, all of the patients’ condition deteriorated rapidly and died in a short time.

Conclusion

The reason of patients’ poor prognosis might be the absence of liver abscess drainage, high level of CSF protein which indicates severe inflammation and unknown special but stronger virulence factors of K. pneumoniae the patients’ living place Zhangjiakou. Strict glycemic control, early drainage of liver abscess and appropriate antibiotic application are recommended for treating this condition, further progress on the pathogenesis and treatment of K. pneumoniae meningitis may help patients gain a better prognosis.

Community-acquired Klebsiella pneumoniae central nervous system infection after acute suppurative otitis

Community-acquired Klebsiella pneumoniae (K. pneumoniae) central nervous system (CNS) infection combined with bacteremia is rarely identified worldwide. We received a 55-year-old woman on long-term corticosteroid therapy for Sjogren's syndrome. Onset began with acute suppurative otitis, followed by a severe headache and loss of consciousness. Cerebrospinal fluid (CSF) testing and brain imaging examinations were compatible with K. pneumoniae meningitis and likely brain abscesses, respectively. K. pneumoniae bacteremia was also found on blood cultures. Despite aggressive antibiotic and supportive therapy, the patient died after 2 day's therapy. Corticosteroid therapy may be a risk factor for a community-acquired K. pneumoniae infection. Appropriate antibiotics and abscess drainage are still recommended, despite the poor prognosis.

Spontaneous community-acquired bacterial meningitis in adults admitted to the intensive care units in the Caribbean French West Indies: Unusual prevalence of Klebsiella pneumonia

An unusual prevalence of Klebsiella pneumoniae (24%) was observed in 25 adults admitted to the intensive care units of two University Hospitals in the French West Indies, for spontaneous community-acquired bacterial meningitis. All tested isolates had several prominent features of hypervirulent isolates, including rmpa and iuc genes, K1 or K2 capsular serotypes.

The First Case of Community-Acquired Pneumonia Due to Capsular Genotype K2-ST86 Hypervirulent Klebsiella pneumoniae in Okinawa, Japan: A Case Report and Literature Review

Hypervirulent Klebsiella pneumoniae (HV-KP) typically causes pyogenic liver abscess and bacteremia with metastatic infections. Community-acquired pneumonia (CAP) due to HV-KP is uncommon and details of its clinical and microbiological features are limited. We report the first case of CAP due to capsular genotype K2-ST86 HV-KP in Okinawa, Japan and review infections caused by the K2-ST86 strain. A 79-year-old woman presenting with fever and productive cough persisting for the past three days was admitted to hospital. Her vital signs indicated septic shock. Lung examination by auscultation revealed holo-crackle and lobar pneumonia in chest radiography, and Streptococcus pneumoniae was suspected. However, sputum and blood cultures revealed Gram-negative coccus identified as K. pneumoniae. Genetic analysis identified the isolated strain as the K2 serotype harboring rmpA, iutA, entB, and mrkD. Therefore, we identified the isolated strain as hypervirulent. The isolate belonged to ST86 as determined by multilocus sequence typing. The case was not complicated by predisposing factors such as diabetes mellitus and malignancy related to HV-KP infection; thus, this CAP-causing HV-KP strain may differ from the typical HV-KP strain that induces liver abscess. A literature review identified only nine cases with CAP due to HV-KP. In all cases, the disease mainly occurred in older males with diabetes mellitus, which makes the present case unusual, and had high rates of septic shock and death. No case, including ours, was complicated by metastatic infection, suggesting that CAP due to HV-KP poses little distant metastasis risk, even in patients with bloodstream infection. In our review, consistent with our case, K2-ST86 was the most common strain of HV-KP in patients with CAP. Therefore, studies are needed to elucidate the clinical and microbiological features of HV-KP CAP, with a focus on the K2-ST86 strain. Physicians should always consider K. pneumoniae in cases of sepsis CAP with lobar pneumonia.

Hypervirulent Klebsiella pneumoniae

Hypervirulent K. pneumoniae (hvKp) is an evolving pathotype that is more virulent than classical K. pneumoniae (cKp). hvKp usually infects individuals from the community, who are often healthy. Infections are more common in the Asian Pacific Rim but are occurring globally. hvKp infection frequently presents at multiple sites or subsequently metastatically spreads, often requiring source control. hvKp has an increased ability to cause central nervous system infection and endophthalmitis, which require rapid recognition and site-specific treatment. The genetic factors that confer hvKp's hypervirulent phenotype are present on a large virulence plasmid and perhaps integrative conjugal elements. Increased capsule production and aerobactin production are established hvKp-specific virulence factors. Similar to cKp, hvKp strains are becoming increasingly resistant to antimicrobials via acquisition of mobile elements carrying resistance determinants, and new hvKp strains emerge when extensively drug-resistant cKp strains acquire hvKp-specific virulence determinants, resulting in nosocomial infection. Presently, clinical laboratories are unable to differentiate cKp from hvKp, but recently, several biomarkers and quantitative siderophore production have been shown to accurately predict hvKp strains, which could lead to the development of a diagnostic test for use by clinical laboratories for optimal patient care and for use in epidemiologic surveillance and research studies.

Getting hypervirulent Klebsiella pneumoniae on the radar screen

PURPOSE OF REVIEW

Two pathotypes of Klebsiella pneumoniae cause human infections, classical (cKp) and hypervirulent (hvKp) K. pneumoniae. The present understanding of genetic elements, the need for an accurate test to identify hvKp, the clinical implications of infection, the knowledge gap on how and why hvKp colonization transitions to infection, and potential infection prevention and control issues for hvKp are discussed.

RECENT FINDINGS

Infections because of hvKp are increasingly recognized worldwide. Its ability to cause organ and life-threatening disease in healthy individuals from the community merits concern, which has been magnified by increasing descriptions of multiply drug-resistant (MDR) and extensively drug-resistant (XDR) strains. Increased capsule and siderophore production by hvKp relative to cKp are critical virulence traits. Asians are most commonly infected, but whether this is mediated by a genetic susceptibility, or increased exposure and colonization is unknown. Specific studies about the epidemiology and transmission of hvKp are lacking, but precautions are appropriate for MDR/XDR strains and perhaps all infected/colonized individuals.

SUMMARY

hvKp is evolving into an increasingly concerning pathogen, in part because of the development of XDR strains. An accurate test to identify hvKp is needed for optimal clinical care, epidemiological, and research studies. An improved understanding of how infection develops, if a genetic susceptibility exists, and appropriate infection prevention and control measures also are needed.

Caribbean multi-centre study of Klebsiella pneumoniae: whole-genome sequencing, antimicrobial resistance and virulence factors

The surveillance of antimicrobial-resistant isolates has proven to be one of the most valuable tools to understand the global rise of multidrug-resistant bacterial pathogens. We report the first insights into the current situation in the Caribbean, where a pilot project to monitor antimicrobial resistance (AMR) through phenotypic resistance measurements combined with whole-genome sequencing was set up in collaboration with the Caribbean Public Health Agency (CARPHA). Our first study focused on Klebsiella pneumoniae, a highly relevant organism amongst the Gram-negative opportunistic pathogens worldwide causing hospital- and community-acquired infections. Our results show that not only carbapenem resistance, but also hypervirulent strains, are circulating in patients in the Caribbean. Our current data does not allow us to infer their prevalence in the population. We argue for the urgent need to further support AMR surveillance and stewardship in this almost uncharted territory, which can make a significant impact on the reduction of antimicrobial usage. This article contains data hosted by Microreact (https://microreact.org).

Antimicrobial Resistance of Hypervirulent Klebsiella pneumoniae: Epidemiology, Hypervirulence-Associated Determinants, and Resistance Mechanisms

Klebsiella pneumoniae is one of the most clinically relevant species in immunocompromised individuals responsible for community-acquired and nosocomial infections, including pneumonias, urinary tract infections, bacteremias, and liver abscesses. Since the mid-1980s, hypervirulent K. pneumoniae, generally associated with the hypermucoviscosity phenotype, has emerged as a clinically significant pathogen responsible for serious disseminated infections, such as pyogenic liver abscesses, osteomyelitis, and endophthalmitis, in a generally younger and healthier population. Hypervirulent K. pneumoniae infections were primarily found in East Asia and now are increasingly being reported worldwide. Although most hypervirulent K. pneumoniae isolates are antibiotic-susceptible, some isolates with combined virulence and resistance, such as the carbapenem-resistant hypervirulent K. pneumoniae isolates, are increasingly being detected. The combination of multidrug resistance and enhanced virulence has the potential to cause the next clinical crisis. To better understand the basic biology of hypervirulent K. pneumoniae, this review will provide a summarization and discussion focused on epidemiology, hypervirulence-associated factors, and antibiotic resistance mechanisms of such hypervirulent strains. Epidemiological analysis of recent clinical isolates in China warns the global dissemination of hypervirulent K. pneumoniae strains with extensive antibiotic resistance in the near future. Therefore, an immediate response to recognize the global dissemination of this hypervirulent strain with resistance determinants is an urgent priority.

Metabolite Transporter PEG344 Is Required for Full Virulence of Hypervirulent Klebsiella pneumoniae Strain hvKP1 after Pulmonary but Not Subcutaneous Challenge

Hypervirulent Klebsiella pneumoniae (hvKP) is an emerging pathotype that is capable of causing tissue-invasive and organ- and life-threatening infections in healthy individuals from the community. Knowledge on the virulence factors specific to hvKP is limited. In this report, we describe a new factor (PEG344) that increases the virulence of hvKP strain hvKP1. peg-344 is present on the hvKP1 virulence plasmid, is broadly prevalent among hvKP strains, and has increased RNA abundance when grown in human ascites. An isogenic derivative of hvKP1 (hvKP1Δpeg-344) was constructed and compared with its wild-type parent strain in in vitro, ex vivo, and infection model studies. Both survival and competition experiments with outbred CD1 mice demonstrated that PEG344 was required for full virulence after pulmonary challenge but, interestingly, not after subcutaneous challenge. In silico analysis suggested that PEG344 serves as an inner membrane transporter. Compared to hvKP1, a small but significant decrease in the growth/survival of hvKP1Δpeg-344 was observed in human ascites, but resistance to the bactericidal activity of complement was similar. These data suggested that PEG344 may transport an unidentified growth factor present in ascites. The data presented are important since they expand our limited knowledge base on virulence factors unique to hvKP, which is needed to lay the groundwork for translational approaches to prevent or treat these devastating infections.

Septicemic invasive Klebsiella pneumoniae infection in a cynomolgus monkey (Macaca fascicularis) with severe diffused suppurative meningoencephalitis

A 2-year-old male cynomolgus monkey (Macaca fascicularis) showed neurological symptoms during quarantine for importation into Japan, and was euthanized due to poor prognosis. Gross anatomical examination revealed a hemorrhagic lesion around the lateral ventricle in the cerebrum. Histologically, severe diffused suppurative meningitis and ventriculitis were detected with numerous Gram-negative bacilli in the cerebrum. Immunohistochemically, the bacilli were positively stained with an antibody against Klebsiella pneumoniae. The bacterium was isolated from the liver, and it was confirmed to be K. pneumoniae by 16S rDNA sequencing. The isolate displayed a hypermucoviscosity phenotype, was positive for the rmpA and k₂A genes, and demonstrated multidrug resistance. These results suggest that invasive K. pneumoniae can cause septicemic infection, characterized by severe diffused suppurative meningoencephalitis in monkeys.