Pyogenic Liver Abscess and Endogenous Endophthalmitis Due to K64-ST1764 Hypervirulent Klebsiella pneumoniae: A Case Report

Clinical features, treatment and prognosis of patients with endogenous infectious endophthalmitis

PURPOSE

To investigate whether the clinical characteristics, treatment and prognosis of endogenous infectious endophthalmitis (EIE) have changed over the past 5 years.

METHODS

Retrospectively analyze all articles about EIE published in the PubMed, Web of Science, and Embase databases from 2017 to 2021.

RESULTS

A total of 128 patients and 147 eyes (46 left and 60 right) were included in the study. The mean age at diagnosis was 51 ± 19 years. The most common risk factors were diabetes and intravenous drug use. From 2017 to 2021, Klebsiella was the most common pathogenic microorganism (22%), and vitreous culture had the highest positivity rate. The most common complaint was blurred vision. The mean visual acuity (logMAR) at onset was 2.84, and the clinical symptoms were vitreal inflammation and opacity (63%), ocular pain (37%), and conjunctival congestion (36%). The ocular inflammation could be reduced by intraocular antibiotics or vitrectomy. However, the visual prognosis, with a mean logMAR of 2.73; only 50% of the eyes reached a visual acuity level of finger count and above. Changes in diagnostics over the past 5 years have mainly manifested as more diverse microorganism culture methods. In addition to conventional culture methods, PCR, sputum culture and aqueous humour culture are also commonly used for the diagnosis of pathogenic bacteria, improving the positive culture rate and visual prognosis.

CONCLUSION

The prognosis of EIE is poor. It is recommended to pay attention to the pathogenic bacteria culture results and accompanying systemic diseases and to diagnose and treat patients as soon as possible.

Genomic insights unveil the plasmid transfer mechanism and epidemiology of hypervirulent Klebsiella pneumoniae in Vietnam

Hypervirulent Klebsiella pneumoniae (hvKp) is a significant cause of severe invasive infections in Vietnam, yet data on its epidemiology, population structure and dynamics are scarce. We screened hvKp isolates from patients with bloodstream infections (BSIs) at a tertiary infectious diseases hospital in Vietnam and healthy individuals, followed by whole genome sequencing and plasmid analysis. Among 700 BSI-causing Kp strains, 100 (14.3%) were hvKp. Thirteen hvKp isolates were identified from 350 rectal swabs of healthy adults; none from 500 rectal swabs of healthy children. The hvKp isolates were genetically diverse, encompassing 17 sequence types (STs), predominantly ST23, ST86 and ST65. Among the 113 hvKp isolates, 14 (12.6%) carried at least one antimicrobial resistance (AMR) gene, largely mediated by IncFII, IncR, and IncA/C plasmids. Notably, the acquisition of AMR conjugative plasmids facilitated horizontal transfer of the non-conjugative virulence plasmid between K. pneumoniae strains. Phylogenetic analysis demonstrated hvKp isolates from BSIs and human carriage clustered together, suggesting a significant role of intestinal carriage in hvKp transmission. Enhanced surveillance is crucial to understand the factors driving intestinal carriage and hvKp transmission dynamics for informing preventive measures. Furthermore, we advocate the clinical use of our molecular assay for diagnosing hvKp infections to guide effective management.

Klebsiella pneumoniae ST147 harboring blaNDM-1, multidrug resistance and hypervirulence plasmids

The spread of hypervirulent (hv) and carbapenem-/multidrug-resistant Klebsiella pneumoniae is an emerging problem in healthcare settings. The New Delhi metallo-β-lactamase-1 (blaNDM-1) is found in Enterobacteriaceae including K. pneumoniae. The blaNDM-1 is capable of hydrolyzing β-lactam antibiotics which are used for treatment of severe infections caused by multidrug-resistant Gram-negative bacteria. This is associated with the unacceptably high mortality rate in immunocompromised burn injury patients. This study reports on the characterization of blaNDM-1 gene and virulence factors in hv carbapenem-/multidrug-resistant K. pneumoniae ST147 in the burns unit of a tertiary teaching hospital during routine surveillance. Two K. pneumoniae strains were obtained from wounds of burn-infected patients from May 2020 to July 2021. The hypervirulence genes and genetic context of the blaNDM-1 gene and mobile genetic elements potentially involved in the transposition of the gene were analyzed. We identified a conserved genetic background and an IS26 and open reading frame flanking the blaNDM-1 gene that could suggest its involvement in the mobilization of the gene. The plasmid harbored additional antibiotic resistance predicted regions that were responsible for resistance to almost all the routinely used antibiotics. To ensure the identification of potential outbreak strains during routine surveillance, investigations on resistance genes and their environment in relation to evolution are necessary for molecular epidemiology.IMPORTANCEData obtained from this study will aid in the prompt identification of disease outbreaks including evolving resistance and virulence of the outbreak bacteria. This will help establish and implement antimicrobial stewardship programs and infection prevention protocols in fragile health systems in countries with limited resources. Integration of molecular surveillance and translation of whole-genome sequencing in routine diagnosis will provide valuable data for control of infection. This study reports for the first time a high-risk clone K. pneumoniae ST147 with hypervirulence and multidrug-resistance features in Ghana.

Klebsiella pneumoniae invasive syndrome with liver, lung, and brain abscesses complicated with pulmonary fungal infection: a case report and review of the literature

BACKGROUND

Klebsiella pneumoniae invasion syndrome (KPIS) is a severe multi-site infection that is usually caused by hypervirulent Klebsiella pneumoniae. The bacteria are relatively common in Asian diabetics and can cause organ abscesses or sepsis. When patients develop intracranial infection, the prognosis is poor. After anti-infective treatment, the Klebsiella pneumoniae-induced liver and lung abscesses and pulmonary fungal infection were relieved, but the brain abscesses worsened. Such complex and severe infection cases are rarely reported. Early identification of intracranial infection, selection of antibiotics with high concentrations in cerebrospinal fluid, and active treatment of complications such as diabetes and fungal infection are of great significance for the prognosis of patients.

CASE PRESENTATION

A 71-year-old patient diagnosed with liver abscess in another hospital was transferred to our hospital due to a worsening condition. On day 1 (day of admission), the patient was given invasive mechanical ventilation, continuous renal replacement therapy combined with endotoxin adsorption, antimicrobial treatment with imipenem-cilastatin, and percutaneous catheter drainage for liver abscess. Metagenomic next-generation sequencing in bronchoalveolar lavage fluid indicated Klebsiella pneumoniae (K. pneumoniae), Candida albicans, and Aspergillus flavus complex, and no viruses were detected. Blood and pus cultures revealed K. pneumoniae that was sensitive to piperacillin/tazobactam. The anti-infection therapy was adjusted to piperacillin/tazobactam combined with voriconazole. On day 14, a head computed tomography (CT) scan showed no significant changes, and a chest CT scan showed absorption of multiple abscesses in both lungs. The patient was still unconscious. After the endotracheal tube was removed, cranial magnetic resonance imaging (MRI) showed multiple brain abscesses. Finally, his family gave up, and the patient was discharged and died in a local hospital.

CONCLUSION

In cases of K. pneumoniae infection, the possibility of intracranial, liver, lung, or other site infections should be considered, and physicians should be vigilant for the occurrence of KPIS. For patients suspected of developing an intracranial infection, cerebrospinal fluid should be tested and cultured as soon as possible, a head MRI should be performed, and antibiotics with high distribution in cerebrospinal fluid should be used early. When patients are complicated with diabetes, in addition to glycemic control, vigilance for concurrent fungal infections is also needed.

"Superbugs" with hypervirulence and carbapenem resistance in Klebsiella pneumoniae: the rise of such emerging nosocomial pathogens in China

Although hypervirulent Klebsiella pneumoniae (hvKP) can produce community-acquired infections that are fatal in young and adult hosts, such as pyogenic liver abscess, endophthalmitis, and meningitis, it has historically been susceptible to antibiotics. Carbapenem-resistant K. pneumoniae (CRKP) is usually associated with urinary tract infections acquired in hospitals, pneumonia, septicemias, and soft tissue infections. Outbreaks and quick spread of CRKP in hospitals have become a major challenge in public health due to the lack of effective antibacterial treatments. In the early stages of K. pneumoniae development, HvKP and CRKP first appear as distinct routes. However, the lines dividing the two pathotypes are vanishing currently, and the advent of carbapenem-resistant hypervirulent K. pneumoniae (CR-hvKP) is devastating as it is simultaneously multidrug-resistant, hypervirulent, and highly transmissible. Most CR-hvKP cases have been reported in Asian clinical settings, particularly in China. Typically, CR-hvKP develops when hvKP or CRKP acquires plasmids that carry either the carbapenem-resistance gene or the virulence gene. Alternatively, classic K. pneumoniae (cKP) may acquire a hybrid plasmid carrying both genes. In this review, we provide an overview of the key antimicrobial resistance mechanisms, virulence factors, clinical presentations, and outcomes associated with CR-hvKP infection. Additionally, we discuss the possible evolutionary processes and prevalence of CR-hvKP in China. Given the wide occurrence of CR-hvKP, continued surveillance and control measures of such organisms should be assigned a higher priority.

Pyogenic liver abscess caused by extended-spectrum β-lactamase-producing hypervirulent Klebsiella pneumoniae diagnosed by third-generation sequencing: a case report and literature review

We report a case of a woman with diabetes mellitus and choledocholithiasis who had a low fever with chills and severe weakness for 7 days. The patient's abdominal tenderness was positive. Computed tomography and magnetic resonance imaging showed a giant abscess in the liver. The production of extended-spectrum β-lactamases by hypervirulent Klebsiella pneumoniae was found in the purulent fluid of the liver by nanopore-based metagenomic third-generation sequencing combined with an antibiotic susceptibility test. The patient recovered after intravenous antibiotic therapy and percutaneous drainage. Patients with a history of diabetes mellitus and choledocholithiasis should be aware of the possibility of pyogenic liver abscesses caused by hypervirulent Klebsiella pneumoniae. To rapidly control the development of this disease, nanopore-based metagenomic third-generation sequencing plays an important role not only in rapidly identifying pathogens, but also in guiding the use of antibiotics.

Molecular epidemiology and clinical characteristics of the type VI secretion system in Klebsiella pneumoniae causing abscesses

Purpose

The type VI system (T6SS) has the potential to be a new virulence factor for hypervirulent Klebsiella pneumoniae (hvKp) strains. This study aimed to characterize the molecular and clinical features of T6SS-positive and T6SS-negative K. pneumoniae isolates that cause abscesses.

Patients and methods

A total of 169 non-duplicate K. pneumoniae strains were isolated from patients with abscesses in a tertiary hospital in China from January 2018 to June 2022, and clinical data were collected. For all isolates, capsular serotypes, T6SS genes, virulence, and drug resistance genes, antimicrobial susceptibility testing, and biofilm formation assays were assessed. Multilocus sequence typing was used to analyze the genotypes of hvKp. T6SS-positive hvKp, T6SS-negative hvKp, T6SS-positive cKP, and T6SS-negative cKP (n = 4 strains for each group) were chosen for the in vivo Galleria mellonella infection model and in vitro competition experiments to further explore the microbiological characteristics of T6SS-positive K. pneumoniae isolates.

Results

The positive detection rate for T6SS was 36.1%. The rates of hvKp, seven virulence genes, K1 capsular serotype, and ST23 in T6SS-positive strains were all higher than those in T6SS-negative strains (p < 0.05). Multivariate logistic regression analysis indicated that the carriage of aerobactin (OR 0.01) and wcaG (OR 33.53) were independent risk factors for T6SS-positive strains (p < 0.05). The T6SS-positive strains had a stronger biofilm-forming ability than T6SS-negative strains (p < 0.05). The T6SS-positive and T6SS-negative strains showed no significant differences in competitive ability (p = 0.06). In the in vivo G. mellonella infection model, the T6SS(+)/hvKP group had the worst prognosis. Except for cefazolin and tegacyclin, T6SS-positive isolates displayed a lower rate of antimicrobial resistance to other drugs (p < 0.05). The T6SS-positive isolates were more likely to be acquired from community infections (p < 0.05).

Conclusion

Klebsiella pneumoniae isolates causing abscesses have a high prevalence of T6SS genes. T6SS-positive K. pneumoniae isolates are associated with virulence, and the T6SS genes may be involved in the hvKp virulence mechanism.

Bilateral Endogenous Klebsiella pneumoniae Endophthalmitis in Culture-Negative Liver Abscess Requiring Evisceration: A Case Report and Review of Literature

Endogenous endophthalmitis is a very rare but potentially devastating intraocular inflammation resulting from hematogenous dissemination into the eye from a remote focus of infection. We present a case of a 49-year-old Vietnamese gentleman with underlying hypertension and ischemic heart disease who presented with sudden onset bilateral eye blurring of vision for five days associated with fever, chills, and rigors. He started to have a chesty cough with right-sided pleuritic chest pain for three days as well as shortness of breath, which developed one day prior to admission. Bilateral ocular examinations and B-scan ultrasonography were consistent with endophthalmitis. A systemic workup was performed and showed multiloculated liver abscess and right lung empyema seen radiologically. Bilateral eye vitreous tap and intravitreal antibiotic injection were performed. He underwent ultrasound-guided pigtail catheter insertion and drainage of the subcapsular and pelvic collection. Microbiological findings revealed Klebsiella pneumoniae infection obtained from vitreous and endotracheal aspirate samples. There were no cultures yielded from the intraabdominal collection and peripheral blood. The right eye infection rapidly progressed to panophthalmitis, which subsequently led to globe perforation despite prompt treatment and eventually required evisceration. Thus, despite culture-negative pyogenic liver abscess in a non-diabetic patient, a high index of suspicion, emergent radiographic evaluation, and prompt intervention and treatment are crucial in salvaging the globes.

Recombinant Reporter Phage rTUN1::nLuc Enables Rapid Detection and Real-Time Antibiotic Susceptibility Testing of Klebsiella pneumoniae K64 Strains

The emergence of multi-drug-resistant Klebsiella pneumoniae (Kp) strains constitutes an enormous threat to global health as multi-drug resistance-associated treatment failure causes high mortality rates in nosocomial infections. Rapid pathogen detection and antibiotic resistance screening are therefore crucial for successful therapy and thus patient survival. Reporter phage-based diagnostics offer a way to speed up pathogen identification and resistance testing as integration of reporter genes into highly specific phages allows real-time detection of phage replication and thus living host cells. Kp-specific phages use the host's capsule, a major virulence factor of Kp, as a receptor for adsorption. To date, 80 different Kp capsule types (K-serotypes) have been described with predominant capsule types varying between different countries and continents. Therefore, reporter phages need to be customized according to the locally prevailing variants. Recently, we described the autographivirus vB_KpP_TUN1 (TUN1), which specifically infects Kp K64 strains, the most predominant capsule type at the military hospital in Tunis (MHT) that is also associated with high mortality rates. In this work, we developed the highly specific recombinant reporter phage rTUN1::nLuc, which produces nanoluciferase (nLuc) upon host infection and thus enables rapid detection of Kp K64 cells in clinical matrices such as blood and urine. At the same time, rTUN1::nLuc allows for rapid antibiotic susceptibility testing and therefore identification of suitable antibiotic treatment in less than 3 h.

Recombination Drives Evolution of Carbapenem-Resistant Klebsiella pneumoniae Sequence Type 11 KL47 to KL64 in China

Carbapenem-resistant Enterobacteriaceae, especially carbapenemase-producing Klebsiella pneumoniae, is an urgent problem in health care facilities worldwide. K. pneumoniae isolates classified as sequence type 11 (ST11) are largely responsible for the spread of carbapenem-resistant K. pneumoniae (CRKP) in China. Our previous phylogenetic reconstruction suggested that CRKP ST11 capsular locus 64 (KL64) was derived from an ST11-KL47 ancestor through recombination. However, the molecular origin of KL64 remains largely unknown, and our understanding of the recombination is incomplete. Here, we screened a global sample of 22,600 K. pneumoniae genomes and searched for KL64-harboring STs, which were found to be ST1764, ST3685, ST1764-1LV, ST30, ST505, ST147, and ST11, wherein ST1764, ST3685, ST1764-1LV, and ST30 belonged to a clonal complex, CC1764. We compared the genetic structures of representative strains from ST11-KL47, ST11-KL64, CC1764-KL64, ST505-KL64, and ST147-KL64 and further performed phylogenetic analysis and single-nucleotide polymorphism analysis among 248 isolates from all these STs. The results suggested a recombination event has occurred in a homologous ~154-kb region covering KL and the lipopolysaccharide biosynthesis locus (OL) between a recipient ST11-KL47-OL101 and a donor CC1764 (except ST30), giving rise to ST11-KL64-O2v1 strains (recombination I). Furthermore, we also found an infrequent ST11-KL64-O2v1 subclone which was not produced by recombination I but was hybridized from ST11-KL47-OL101 and ST147-KL64-O2v1 strains through recombination of a homologous ~485-kb region covering KL and OL (recombination II). Our findings provide important insights into the role of recombination in the evolution of clinical strains and the diversity of capsule and lipopolysaccharide of widely distributed KPC-associated ST11 K. pneumoniae in China. IMPORTANCE Chromosomal recombination events are considered to contribute to the genetic diversification and ultimate success of many bacterial pathogens. A previous study unravelled the molecular evolution history of ST258 strains, which have been largely responsible for the spread of KPC in the United States. Here, we used comparative genomic analyses to discover two recombination events in ST11 CRKP strains, which is a predominant KPC-associated CRKP clone in China. Two new ST11-CRKP subclones with altered capsule and lipopolysaccharide, which are two primary determinants of antigenicity and antigenic diversity among K. pneumoniae, were produced through these two recombination events, respectively. Horizontal transfer of the KL and OL appears to be a crucial element driving the molecular evolution of K. pneumoniae strains. These findings not only extend our understanding of the molecular evolutionary history of ST11 but also are an important step toward the development of preventive, diagnostic, and therapeutic strategies for CRKP.

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.

Hypervirulent Klebsiella pneumoniae Endogenous Endophthalmitis-A Global Emerging Disease

The review aims to document the new emerging hypervirulent Klebsiella pneumoniae (Kp) endogenous endophthalmitis (EKE) in terms of incidence, microbiological characterization of the pathogenic agent, associated risk factors, management, and outcomes. Hypervirulent (hv) strains of KP (hvKp) induce invasive liver abscesses (LA) with specific clinical features. Up to 80–90% of cases have hepatic liver abscess as a primary focus of infection, followed by renal or lung hvKp infections. However, the incidence of EKE in patients with KPLA varied between 3.4% (19) and 12.6% (13), with a total of 95 cases of endophthalmitis in 1455 cases of KPLA (6.5%). Severe visual loss was encountered in 75% of cases, with 25% bilateral involvement. Intravitreal antibiotics are the mainstay therapeutic approach. Pars plana vitrectomy is a subject of controversy. HvKp strains present mostly natural “wild-type” antibiotic resistance profile suggestive for community-acquired infections, being highly susceptive to the third and fourth generation of cephalosporins and carbapenems. Antimicrobial resistance in hypervirulent strains was recently documented via plasmid transfer and may result in extremely difficult to treat cases. Global dissemination of these strains is a major epidemiologic shift that should be considered in the diagnostic and therapeutic management of patients with endogenous endophthalmitis. Ophthalmologic screening in patients with KPLA and other hvKp infections and a multidisciplinary therapeutic approach is extremely important for early diagnosis and preservation of the visual function.