Pyogenic liver abscess caused by Klebsiella pneumoniae genetic serotype K1 in Japan

Clinical features and development of Sepsis in Klebsiella pneumoniae infected liver abscess patients: a retrospective analysis of 135 cases

Background

Klebsiella pneumoniae is a primary pathogen of pyogenic liver abscess (PLA). However, little data are available on combination with sepsis. In this study, we aimed to evaluate the clinical characteristics and prognostic differences of PLA patients with sepsis.

Methods

This retrospective cohort study was conducted to investigate 135 patients with confirmed Klebsiella pneumoniae-caused liver abscesses (KPLA) from a tertiary teaching hospital, from 2013 to 2019. The patients were divided into two groups, KPLA with sepsis and KPLA without sepsis. The demographic characteristics, clinical features as well as laboratory and microbiologic findings were analyzed.

Results

A total of 135 patients with KPLA were analyzed. The mean age of patients was 60.9 ± 12.7 years, and the percentage of men was 59.3%. Among them, 37/135 (27.4%) of patients had sepsis and the mortality rate was 1.5%. The most common symptom was fever (91.1%). KPLA patients with sepsis had a significantly higher proportion of frailty, diarrhea, fatty liver, chronic renal insufficiency, and hepatic dysfunction compared to KPLA patients without sepsis (p < 0.05). Antibiotic therapy and percutaneous drainage were most frequently therapeutic strategy. Furthermore, the incidences of sepsis shock and acute respiratory distress syndrome were higher in the sepsis group compared to the non-sepsis group. As for metastatic infections, the lung was the most common site. In addition, KPLA patients with sepsis showed respiratory symptoms in 11 patients, endophthalmitis in 4 patients, and meningitis in 1 patient.

Conclusion

Our findings emphasize that KPLA patients combined with or without sepsis have different clinical features, but KPLA patients with sepsis have higher rates of complications and metastatic infections. Taken together, further surveillance and control of septic spread is essential for KPLA patients.

Clinical and microbiological characteristics of pyogenic liver abscess in a tertiary hospital in East China

Pyogenic liver abscess (PLA) is a potentially life-threatening disease affecting many parts of the world, especially Asia. In this study, we explored the clinical and microbiological characteristics of PLA in Chinese patients.A 5-year (2010-2014) retrospective review of medical records on all PLA patients who were admitted to a tertiary teaching hospital was performed.Among 217 PLA cases who were confirmed cultural positive, Klebsiella pneumonia (K pneumonia) was the most common pathogen (n = 165, 76.0%), followed by Escherichia coli (n = 21, 9.7%). Notably, there is a higher incidence of diabetes mellitus in patients with K pneumoniae-induced PLA (KP-PLA) than that with non-K pneumoniae-induced PLA (non-KP-PLA)(43.0% vs 21.2%, P = .005). However, it was less prevalent for concomitant hepatobiliary disease (20.0% vs 34.6%, P = .039) and history of intraabdominal trauma or surgery (13.3% vs 38.5%, P < .001) in patients with KP-PLA. Although K pneumoniae are sensitive to most common antibiotics (antibiotic resistance rates below 10%), some strains (1.2%) developed resistant to carbapenem. These results confirmed K pneumoniae as the predominant pathogen of PLA in the area in which the study was conducted. More attention should be directed toward monitoring the emergence of carbapenem-resistant K pneumoniae.KP-PLA is frequently diagnosed in patients with metabolic diseases accompanied by serious consequences, and it is therefore prudent to see that they receive sensitivity-directed antibiotic therapy.

Invasive liver abscess syndrome caused by Klebsiella pneumoniae with definite K2 serotyping in Japan: a case report

Background

Klebsiella pneumonia is a well-known human pathogen, and recently, a distinct invasive syndrome caused by K. pneumoniae serotypes K1 and K2 has been recognized in Southeast Asia. This syndrome is characterized by primary liver abscess and extrahepatic complications resulting from bacteremic dissemination. We report the first adult case of primary liver abscess caused by the definite K2 serotyped pathogen, with endogenous endophthalmitis in Japan.

Case presentation

A 64-year-old woman was admitted to a nearby hospital for a high fever and diarrhea. She had visual loss of her right eye, renal dysfunction, and thrombocytopenia within 24 h from admission. She was transferred to our institution. On admission, she had no alteration of mental status and normal vital signs; however, she had almost complete ablepsia of the right eye. Laboratory data showed severe inflammation, liver dysfunction, thrombocytopenia, an increased serum creatinine level, and coagulopathy. Computed tomography showed a low density area in the right lobe of the liver. Invasive liver abscess syndrome probably caused by K. pneumonia was highly suspected and immediately administered broad-spectrum antibiotics for severe sepsis. Concurrently, endogenous endophthalmitis was diagnosed, and we performed vitrectomy on the day of admission. The blood culture showed K. pneumoniae infection. Percutaneous drainage of the liver abscess was also performed. Although she was discharged in a good general condition on day 22, she had complete ablepsia of the right eye. The K2A gene was detected by polymerase chain reaction (PCR), which is consistent with the K2 serotype. PCR was also positive for the virulence-associated gene rmpA. Final diagnosis was invasive liver abscess syndrome caused by K2 serotype K. pneumonia.

Conclusions

Although the primary liver abscess caused by K. pneumoniae with a hypermucoviscous phenotype is infrequently reported outside Southeast Asia, physicians should recognize this syndrome, and appropriate diagnosis and treatment is essential for saving patients’ lives and preserving organ function, especially for visual acuity.

Influence of the bacterial phenotypes on the clinical manifestations in Klebsiella pneumoniae bacteremia patients: A retrospective cohort study

Ninety-four episodes of Klebsiella pneumoniae bloodstream infection were identified at a university hospital in Japan. After excluding extended-spectrum beta lactamase-producing strains, 83 blood isolates from these patients were assayed in terms of their bacterial phenotypes such as the mucoid and hypermucoviscosity phenotypes. Bacterial phenotypes were correlated with the patients' clinical manifestations. The hypermucoviscosity phenotype was significantly associated with septic shock at the onset of infections (odds ratio, 15.92; 95% confidence interval, 1.27-468.12), but was not associated with liver abscess formation. Mortality was determined by the presence of septic shock. RmpA gene was associated with the induction of the hypermucoviscosity phenotype. These results reveal unique roles of bacterial phenotypes on the patient's clinical condition in K. pneumoniae bacteremia.

Identification of an immuno-dominant protein from Klebsiella pneumoniae strains causing pyogenic liver abscess: implication in serodiagnosis

Background

Klebsiella pneumoniae has emerged worldwide as a cause of pyogenic liver abscess (PLA) often complicated by meningitis and endophthalmitis. Early detection of this infectious disease will improve its clinical outcome. Therefore, we tried to isolate immunodominant proteins secreted by K. pneumoniae strains causing PLA.

Results

The secreted proteins of the NTUH-K2044 strain were separated by two-dimensional electrophoresis and then immunoblotted using convalescent sera from patients with K. pneumoniae PLA. A ~30-kDa immunodominant protein was then identified. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) revealed an open reading frame (KP1_p307) located on the pK2044 plasmid and bioinformatic analysis identified this protein as a signal peptide of unknown function. The KP1_p307 gene was more prevalent in PLA strains and capsular type K1/K2 strains, but disruption of this gene in NTUH-K2044 strain did not decrease virulence in mice. Ten of fourteen (71%) sera from patients with K. pneumoniae PLA were immunoreactive with the recombinant KP1_p307 protein. Seroconversion demonstrated by a rise in serum titer in serial serum samples confirmed that antibodies against the KP1_p307 protein were elicited after infection.

Conclusions

The KP1_p307 protein could be used as an antigen for early serodiagnosis of K. pneumoniae PLA, particularly in K1/K2 PLA strains.

Predictors of therapy failure in a series of 741 adult pyogenic liver abscesses

BACKGROUND

Adult pyogenic liver abscess (PLA) is a major hepato-biliary infection. We aim to identify risk factors associated with therapy failure.

METHODS

Retrospective study of 741 PLA patients (2001-2011) and comparison with earlier data (1994-1997). Risk factors associated with therapy failure were identified with multivariate analysis.

RESULTS

Incidence of PLA is 86/100 000 admissions, with average size 5.75 cm. 68% of PLA were secondary to Klebsiella pneumoniae and there is increasing extended-spectrum beta-lactamase (ESBL) resistance. Compared with 1990s, there is an increasing annual incidence (from 18 to 67). Elderly age (≥55-years-old), presence of multiple abscesses, malignancy as etiology and patients who underwent endoscopic intervention are independent predictors for failure of antibiotics-only therapy while average intravenous antibiotics duration and average abscess size are not. ECOG performance status ≥2, pre-existing hypertension and hyperbilirubinaemia are independent predictors for failure of percutaneous therapy while the presence of multiple abscesses and average abscess size are not.

CONCLUSION

There is an increasing PLA incidence with increasing ESBL resistance. Percutaneous drainage should be considered early for elderly patients (≥55-years-old), with multiple abscesses, malignancy as etiology or who required endoscopic intervention. We should have a low threshold for surgical intervention for patients with ECOG performance status ≥2, co-morbidity of hypertension or hyperbilirubinaemia.

Isolation of a bacteriophage and its depolymerase specific for K1 capsule of Klebsiella pneumoniae: implication in typing and treatment

BACKGROUND

Klebsiella pneumoniae causing community-acquired pyogenic liver abscess complicated with metastatic meningitis and endophthalmitis has emerged recently, most frequently associated with the K1 capsular type.

METHODS

A bacteriophage (NTUH-K2044-K1-1) that infects K. pneumoniae NTUH-K2044 (capsular type K1) was isolated and characterized.

RESULTS

The phage infected all K1 strains, and none of the strains with other capsular types. Capsule deletion mutants were not lysed by this phage, suggesting that the capsule was essential for phage infection. Complete genome sequencing revealed the phage was a novel phiKMV-like virus. The gene-encoding capsule depolymerase was identified. The recombinant enzyme demonstrated specific lysis of the K1 capsule. Treatment with the phage or the recombinant enzyme provided significantly increased survival in mice infected with NTUH-K2044 strain, including one treated after the detection of a neck abscess by imaging. No obvious disease was observed after administration of this phage in mice. Phage was retained at detectable levels in liver, spleen, brain, and blood 24 hours after administration in mice.

CONCLUSIONS

These results demonstrate this phage and its capsule depolymerase exhibit specificity for capsular type K1 and can be used for the diagnosis and treatment of K1 K. pneumoniae infections.

Capsule deletion via a λ-Red knockout system perturbs biofilm formation and fimbriae expression in Klebsiella pneumoniae MGH 78578

Background

Klebsiella pneumoniae is a leading cause of hospital-acquired urinary tract infections and pneumonia worldwide, and is responsible for many cases of pyogenic liver abscess among diabetic patients in Asia. A defining characteristic of this pathogen is the presence of a thick, exterior capsule that has been reported to play a role in biofilm formation and to protect the organism from threats such antibiotics and host immune challenge.

Findings

We constructed two knockout mutants of K. pneumoniae to investigate how perturbations to capsule biosynthesis alter the cellular phenotype. In the first mutant, we deleted the entire gene cluster responsible for biosynthesis of the extracellular polysaccharide capsule. In the second mutant, we deleted the capsule export subsystem within this cluster. We find that both knockout mutants have lower amounts of capsule but produce greater amounts of biofilm. Moreover, one of the two mutants abolishes fimbriae expression as well.

Conclusions

These results are expected to provide insight into the interaction between capsule biosynthesis, biofilm formation, and fimbriae expression in this organism.

Ampicillin and amoxicillin use and the risk of Klebsiella pneumoniae liver abscess in Taiwan

BACKGROUND

Klebsiella pneumoniae liver abscess (KPLA) is prevalent in East Asia. Use of amoxicillin/ampicillin may lead to overgrowth of K. pneumoniae in the intestine and predispose to KPLA. We used an animal study and nationwide population-based database to investigate the association between ampicillin/amoxicillin use and KPLA in Taiwan.

METHODS

In an animal study, ampicillin or sterile water was administered orogastrically in serotype K1 K. pneumoniae-colonized mice and the outcome was compared. We identified 855 cases with liver abscess and selected 3420 age- and sex-matched control subjects from the National Health Insurance Research Database. Conditional logistic regression was used to estimate the adjusted odds ratios (ORs) for the association between recent use of ampicillin/amoxicillin and KPLA.

RESULTS

Ampicillin administration predisposed K. pneumoniae-colonized mice to increased bacterial burden, liver abscess and necrosis, and lethality. The population-based study showed that the adjusted OR associating the use of ampicillin/amoxicillin within the past 30 days with KPLA was 3.5 (95% confidence interval, 2.5-5.1). No association was found with use in the past 31-90 days.

CONCLUSIONS

Ampicillin/amoxicillin therapy started within the past 30 days was associated with increased risk for KPLA. We should avoid the overuse of these antibiotics to prevent undesired disease in the endemic area.

Klebsiella pneumoniae liver abscess in diabetic patients: association of glycemic control with the clinical characteristics

Background

Klebsiella pneumoniae liver abscess (KPLA) has been reported with increasing frequency in East Asian countries in the past 3 decades, especially in Taiwan and Korea. Diabetes is a well-known risk factor for KPLA and highly associated with septic metastatic complications from KPLA. We investigated the association of glycemic control in diabetic patients with the clinical characteristics of KPLA in Taiwan.

Methods

Adult diabetic patients with KPLA were identified retrospectively in a medical center from January 2007 to January 2012. Clinical characteristics were compared among patients with different levels of current hemoglobin A1c (HbA_1c). Risk factors for metastatic infection from KPLA were analyzed.

Results

Patients with uncontrolled glycemia (HbA_1c ≥ 7%) were significantly younger than those with controlled glycemia (HbA_1c < 7%). Patients with uncontrolled glycemia had the trend to have a higher rate of gas-forming liver abscess, cryptogenic liver abscess, and metastatic infection than those with controlled glycemia. Cryptogenic liver abscess and metastatic infection were more common in the poor glycemic control group (HbA_1c value >; 10%) after adjustment with age. HbA_1c level and abscess < 5 cm were independent risk factors for metastatic complications from KPLA.

Conclusions

Glycemic control in diabetic patients played an essential role in the clinical characteristics of KPLA, especially in metastatic complications from KPLA.

Septic arthritis subsequent to urosepsis caused by hypermucoviscous Klebsiella pneumoniae

We herein report the first case of septic arthritis caused by rmpA-positive hypermucoviscous community-acquired K. pneumoniae that followed urosepsis in a 65-year-old Japanese woman. The patient responded well to drainage of the abscesses and treatment with cefazolin. Although this virulent phenotype of K. pneumoniae has been primarily reported in Hong Kong, we confirmed that 18/50 isolates obtained in our hospital over the past five years displayed the hypermucoviscous phenotype. Therefore, clinicians should consider the possibility of an increasing prevalence of rmpA-positive hypermucoviscous K. pneumoniae infection in Japan and be particularly vigilant for invasive clinical manifestations, even in patients with urinary tract infections.

Multiple-omic data analysis of Klebsiella pneumoniae MGH 78578 reveals its transcriptional architecture and regulatory features

Background

The increasing number of infections caused by strains of Klebsiella pneumoniae that are resistant to multiple antibiotics has developed into a major medical problem worldwide. The development of next-generation sequencing technologies now permits rapid sequencing of many K. pneumoniae isolates, but sequence information alone does not provide important structural and operational information for its genome.

Results

Here we take a systems biology approach to annotate the K. pneumoniae MGH 78578 genome at the structural and operational levels. Through the acquisition and simultaneous analysis of multiple sample-matched –omics data sets from two growth conditions, we detected 2677, 1227, and 1066 binding sites for RNA polymerase, RpoD, and RpoS, respectively, 3660 RNA polymerase-guided transcript segments, and 3585 transcription start sites throughout the genome. Moreover, analysis of the transcription start site data identified 83 probable leaderless mRNAs, while analysis of unannotated transcripts suggested the presence of 119 putative open reading frames, 15 small RNAs, and 185 antisense transcripts that are not currently annotated.

Conclusions

These findings highlight the strengths of systems biology approaches to the refinement of sequence-based annotations, and to provide new insight into fundamental genome-level biology for this important human pathogen.

Necrotizing fasciitis following psoas muscle abscess caused by hypermucoviscous Klebsiella pneumoniae

A 59-year-old Japanese diabetic woman was admitted to a small private hospital with general malaise, fever, and a 1-month history of low back pain. A computed tomography scan of the abdomen revealed left abdominal necrotizing fasciitis with suspected left psoas muscle abscess. She was transferred to Gunma University Hospital, received antibiotic therapy, and underwent debridement of the infected subcutaneous tissue, fascia, and necrotic left psoas muscle. She was transferred to the intensive care unit to receive mechanical ventilation and inotropic support. Blood culture showed growth of Klebsiella pneumoniae, from which hypermucoviscosity was detected by the string test. She was extubated on day 5 of hospitalization and transferred to a general ward on day 14. Free skin grafting was performed on day 76, and she was discharged on day 134 without any complications.

The role of Klebsiella pneumoniae rmpA in capsular polysaccharide synthesis and virulence revisited

Klebsiella pneumoniae community-acquired pyogenic liver abscess (PLA) is an emerging infectious disease. The rmpA gene (for regulator of mucoid phenotype A) has been reported to be associated with PLA in prevalence studies. NTUH-K2044, a K1 PLA isolate, carries three rmpA/A2 genes: two large-plasmid-carried genes (p-rmpA and p-rmpA2) and one chromosomal gene (c-rmpA). In this study, we re-examined the role of rmpA/A2 in PLA pathogenesis to clarify the relationship of rmpA/A2 and capsular serotype to virulence. Using isogenic gene deletion strains and complemented strains of NTUH-K2044, we demonstrated that only p-rmpA enhanced expression of capsular polysaccharide synthesis (cps) genes and capsule production. Nevertheless, the lethal dose and in vivo competitive index indicated that p-rmpA does not promote virulence in mice. The prevalence of these three rmpA/A2 and capsular types in 206 strains was investigated. This revealed a correlation of rmpA/A2 with six PLA-related capsular types (K1, K2, K5, K54, K57 and KN1). However, the correlation of rmpA/A2 with K1 strains from the West was less obvious than with the strains from Asia (17/22 vs 39/39, P = 0.0019). Among the three rmpA/A2 genes, p-rmpA was the most prevalent. Due to the strong correlation with PLA-related capsular types, p-rmpA could serve as a surrogate marker for PLA. We found an association of p-rmpA with three widely spaced loci in a large plasmid (30/32). Therefore, rmpA could be co-inherited together with virulence genes carried by this plasmid.

Molecular typing and virulence analysis of serotype K1 Klebsiella pneumoniae strains isolated from liver abscess patients and stool samples from noninfectious subjects in Hong Kong, Singapore, and Taiwan

Serotype K1 Klebsiella pneumoniae with multilocus sequence type 23 (ST23) has been strongly associated with liver abscess in Taiwan. Few data regarding the strain types and virulence of this serotype from other Asian countries are available. Serotype K1 K. pneumoniae strains isolated from liver abscess and stool samples from subjects hospitalized in Hong Kong, Singapore, and Taiwan hospitals were examined. Forty-seven serotype K1 isolates were identified: 26 from liver abscess samples and 21 from stool samples. MLST revealed 7 sequence types: 85.1% (40 of 47 isolates) belonged to ST23, 1 isolate belonged to ST163 (a single-locus variant of ST23), and 2 isolates were ST249 (a 3-locus variant of ST23). New STs, namely, ST367, ST425, and ST426, were allocated to 3 of 4 isolates from stool samples. The virulence of these strains was determined by neutrophil phagocytosis and mouse infection models. Except for two ST23 isolates, all Klebsiella pneumoniae isolates were resistant to phagocytosis. Resistance to serum killing varied in isolates of ST23, while all non-ST23 strains were susceptible to serum killing except one with ST249 from a liver abscess. All hypervirulent isolates with a 50% lethal dose of <10(2) CFU were from ST23, were resistant to phagocytosis and serum killing, and also carried both virulence-associated genes, rmpA and aerobactin. Multilocus sequence typing genotype 23 was the most prevalent sequence type among serotype K1 K. pneumoniae isolates from both liver abscess and stool samples in the Asia Pacific region. Serotype K1 K. pneumoniae isolates with capsule expression leading to phagocytic resistance and with the aerobactin gene were associated with hypervirulence.

Familial spread of a virulent clone of Klebsiella pneumoniae causing primary liver abscess

Capsule-forming Klebsiella pneumoniae K1 caused primary liver abscess in two household members of a family. The causative isolates had identical pulsed-field gel electrophoresis patterns and were determined to be sequence type 23. An additional member of the family was found to carry the same strain without clinical manifestation.