Tropical liver abscess

Identification of hypervirulent Klebsiella pneumoniae isolates using the string test in combination with Galleria mellonella infectivity

Distinguishing between hypervirulent Klebsiella pneumoniae (hvKp) and classical Klebsiella pneumoniae (cKp) is a challenge to clinical laboratories. The aim of this study was to determine the practicability of combining the G. mellonella killing assay with a string test to differentiate hvKp from cKp. One hundred and three clinical K. pneumoniae isolates were collected. PCR amplification and wzi sequencing were used to determine the capsular serotype. Virulence genes allS, iro, iuc, and rmpA2, used frequently to identify hvKp, were detected by PCR. The virulence of K. pneumoniae isolates was evaluated using the following assays in parallel: molecular markers detection, G. mellonella killing assay alone, G. mellonella killing assay combined with the string test, and mouse infection. The results showed that the sensitivity, specificity, positive predictive value, and negative predictive value of combining the G. mellonella killing assay with a string test were 95.56%, 94.83%, 93.48%, and 96.49%, respectively, compared with mouse infection used as a positive reference. These values were significantly greater than those obtained using the G. mellonella killing assay only. The sensitivity, specificity, positive predictive value, and negative predictive value of allS, iro, iuc, and rmpA2 were greater than 77.78%, but less than combining the G. mellonella killing assay and string test. G. mellonella killing assay used in conjugation with the string test is a relatively simple and accurate method to assess K. pneumoniae virulence and differentiate between hvKp and cKp.

Hypervirulence and carbapenem resistance: two distinct evolutionary directions that led high-risk Klebsiella pneumoniae clones to epidemic success

Introduction: Over the past few decades, Klebsiella pneumoniae has become a significant threat to public health and is now listed as an ESKAPE pathogen. Evolving with versatile capabilities, K. pneumoniae is a population composed of genetically and phenotypically diverse bacteria. However, epidemic K. pneumoniae are restricted to specific clonal lineages. The clonal group CG23 comprises hypervirulent K. pneumoniae displaying limited resistance to antimicrobials and is frequently associated with the community-acquired invasive syndrome. On the other hand, CG258 is another clonal group of K. pneumoniae that has evolved resistance to carbapenems, primarily by acquiring the carbapenemase-encoding genes through nosocomial carriage. Areas covered: With a focus on the high-risk K. pneumoniae clonal lineages CG23 and CG258, we review recent advances including the newly discovered lineage-specific genomic features, and the molecular basis of K. pneumoniae-associated epidemiology, antimicrobial resistance, and hypervirulence. Expert opinion: Both CG23 and CG258 can establish reservoirs in susceptible individuals. Empirical antimicrobial regimens that are prescribed for immediate treatments frequently create selective pressures that favor the high-risk lineages to develop into prominent colonizers. This dilemma reinforces the need for effective therapies that require rapid and accurate diagnosis of epidemic K. pneumoniae.

Septic cutaneous emboli revealing a severe case of Klebsiella pneumoniae liver abscess syndrome

Introduction

Klebsiella pneumoniae liver abscess syndrome (KLAS) is characterized by bacteraemia, liver abscesses and metastatic infection caused by a hypervirulent strain of Klebsiella pneumoniae, usually belonging to the capsular serotype K1 or K2. Initially, KLAS was described in Eastern Asia; recently isolated cases have been reported from different parts of the world.

Case presentation

We describe the case of a woman with KLAS including meningeal, ocular and cutaneous metastatic infection and organ dysfunctions (coagulation abnormalities, thrombocytopenia and increased creatinine level). The identification of a hypermucoviscous strain of Klebsiella pneumoniae was possible by culture from one of the cutaneous emboli and subsequently confirmed by blood cultures. The patient fully recovered after abscess drainage and prolonged antibiotic treatment.

Conclusion

We have pointed out about the importance of sampling each septic focus in order to identify the aetiology of a disseminate infection.

Antibody-Based Immunotherapy To Treat and Prevent Infection with Hypervirulent Klebsiella pneumoniae

Hypervirulent Klebsiella pneumoniae (hvKp) strains are predicted to become a major threat in Asia if antibiotic resistance continues to spread. Anticapsular antibodies (Abs) were developed because disseminated infections caused by hvKp are associated with significant morbidity and mortality, even with antibiotic-sensitive strains. K1-serotype polysaccharide capsules (K1-CPS) are expressed by the majority of hvKp strains. In this study, K1-CPS-specific IgG Abs were generated by conjugation of K1-CPS to immunogenic anthrax protective antigen (PA) protein. Opsonophagocytic efficacy was measured in vitro and in vivo by intravital microscopy in murine livers. In vivo protection was tested in murine models, including a novel model for dissemination in hvKp-colonized mice. Protective efficacy of monoclonal antibodies (MAbs) 4C5 (IgG1) and 19A10 (IgG3) was demonstrated both in murine sepsis and pulmonary infection. In hvKp-colonized mice, MAb treatment significantly decreased dissemination of hvKp from the gut to mesenteric lymph nodes and organs. Intravital microscopy confirmed efficient opsonophagocytosis and clearance of bacteria from the liver. In vitro studies demonstrate that MAbs work predominantly by promoting FcR-mediated phagocytosis but also indicate that MAbs enhance the release of neutrophil extracellular traps (NETs). In anticipation of increasing antibiotic resistance, we propose further development of these and other Klebsiella-specific MAbs for therapeutic use.

Rising trends of endogenous Klebsiella pneumoniae endophthalmitis in Australia

BACKGROUND

Endogenous Klebsiella pneumoniae endophthalmitis (EKPE) is a well-known entity in South-East Asia. We demonstrate a range of differing clinical features and outcomes of EKPE, and highlight the increasing incidence of EKPE in major centres in Sydney and Melbourne, Australia.

DESIGN

Retrospective observational case study and case series in the hospital setting.

PARTICIPANTS

Four cases of EKPE.

METHODS

EKPE cases from 2005 to 2015 were identified through established endophthalmitis databases as well as hospital-based microbiological searches.

MAIN OUTCOME MEASURES

EKPE cases were confirmed with positive K. pneumoniae intraocular samples.

RESULTS

Rising trends of EKPE were noted in major centres in Australia. Six eyes of four patients with EKPE from January 2011 to December 2015 are reported. The mean age was 49 years (range 43-58 years). Two patients had bilateral involvement. There were systemic symptoms up to 10 days prior to ocular symptoms. The source of sepsis in all cases was a hepatic abscess. Two patients had diabetes mellitus. Five eyes had hypopyon panuveitis on presentation. All eyes underwent vitrectomy. The patient with the most delayed presentation underwent enucleation following globe perforation. Final best corrected visual acuity (BCVA) in one patient with bilateral EKPE was light perception (LP) only. The other three eyes had BCVA in at least one eye of 6/24 or better.

CONCLUSIONS

EKPE is an emerging condition in Australia. Although rare, EKPE is a sight-threatening and potentially life-threatening emergency that can initially present to ophthalmologists. One should suspect EKPE in septic patients with a B-scan showing a vitreous or retinal abscess.

Epidemiology, Clinical Features and Outcome of Liver Abscess: A single Reference Center Experience in Qatar

OBJECTIVE

To describe the etiology, clinical presentation, management and outcome of liver abscess in adult patients admitted at Hamad general hospital, Qatar.

METHODS

A cross sectional study was conducted to involve all adult patients who sequentially encountered episodes of liver abscess during the period from January 1, 2009, to December 31, 2010. Blood cultures were drawn from all patients in the first 24 hours after admission. In addition, all patients had stool examinations and indirect Hemagglutination test for Entameba histolytica. Aspiration of abscess was done under CT guidance and aspirated pus was sent for gram stain and culture.

RESULTS

In total, 67 patients were admitted with liver abscess; 56 patients with pyogenic liver abscess and 11 with amebic liver abscess. There were 61 (91%) males and six (9%) females and their mean age was 47.4 ± 18.5 years. Fever, abdominal pain and vomiting were the commonest presenting features. Of the 56 pyogenic liver abscess patients, four discharged against medical advice and seven refused all invasive procedures and were treated with antibiotics for six weeks. The remaining 44 (79%) patients were treated with antibiotics and one or more invasive procedures, while one patient was treated surgically. The commonest organism isolated was Klebseilla pneumonia found in 21 patients (38%). The mean duration of hospitalization was 13.6 ± 8.1 days; the mean duration of antibiotic therapy was 34.7 ± 40.6 days, and one patient died. In contrast, all amebic liver abscess patients underwent ultrasound guided aspiration and showed good response to metronidazole treatment. Their mean duration of hospitalization was 7.7 ± 4.1 days, mean duration of therapy was 11.8 ± 2.1 days, and all patients were cured.

CONCLUSION

Pyogenic liver abscess was more common than amebic liver abscess with Klebseilla pneumonia being the commonest organism. With good medical measures and early drainage of liver abscess, surgical intervention was unnecessary in almost all the cases.

Different metabolic profiles of K1 serotype and non-serotype K1 and K2 Klebsiella pneumoniae isolates in oral infection mice model

K1 or K2 serotype Klebsiella pneumoniae isolate caused clinical pyogenic liver abscess (KLA) infection is prevalent in many areas. It has been identified that K1 or K2 serotype K. pneumoniae isolates caused KLA infection in mice by oral inoculation. In our study, K1 serotype K. pneumoniae isolate Kp1002 with hypermucoviscosity (HV)-positive phenotype caused KLA infection in C57BL/6 mice by oral inoculation. Simultaneously, non-serotype K1 and K2 isolate Kp1014 with HV-negative phenotype failed to cause KLA infection in the same manner. It seems that gastrointestinal tract translocation is the pathway by which K1 or K2 serotype K. pneumoniae caused KLA infection. Liquid chromatography-tandem mass spectrometry was used to further analyze metabolic profile changes in mice with KLA infection. Data showed that after Kp1002 or Kp1014 oral inoculation, serum Phosphatidylcholine (PC) and Lysophosphatidylcholine (LPC) levels significantly changed in mice. Some PC and LPC molecules showed changes both in the Kp1002 KLA group and the Kp1014 no-KLA group compared with the control group. The level of 18:1/18:2-PC significantly changed in the Kp1002 KLA group compared with the control group, but showed no change between the Kp1014 no-KLA group and the control group. The level of 18:1/18:2-PC might have been particularly affected by KLA infection caused by K1 serotype K. pneumoniae Kp1002. It may be a potential biomarker for KLA infection.

Liver abscess in the tropics: an experience from Jammu

OBJECTIVE

To study the various types of liver abscesses. This prospective study was conducted over a period of one year, from November 2011 to October 2012, at the Department of General Surgery in Acharya Shri Chander College of Medical Sciences and Hospital Sidhra, Jammu.

MATERIALS AND METHODS

The patients in this study were admitted from the emergency wing, and from indoor and outdoor departments of surgery and medicine over a period of one year (November 2011 to October 2012) to the Department of General Surgery in Acharya Shri Chander College of Medical Sciences and Hospital Sidhra, Jammu. Patients of all age groups and both genders who presented with clinical suspicion of liver abscess, or had already been diagnosed, were included in the study. A definitive diagnosis of liver abscess was made based on compatible clinical features, ultrasonography and aspiration or drainage of pus. Diagnostic criteria for the various types of abscesses were as follows: Amoebic abscess: demonstration of Entamoeba histolytica trophozoites in aspirated pus. Pyogenic abscess: positive cultures of blood or aspirated pus. If both of the above sets of criteria were satisfied, the abscess was considered to be of mixed aetiology. Tuberculous abscess was diagnosed by identifying acid-fast bacilli in aspirated material and polymerase chain reaction. The abscess was classified as indeterminate if none of the above criteria were satisfied.

RESULTS

The majority of patients in our study had amoebic liver abscesses (73.33%). Escherichia coli and Klebsiella were the most common organisms cultured from the pyogenic abscesses. The majority of patients with amoebic liver abscesses were treated with drug therapy alone, whereas all pyogenic liver abscesses required some form of drainage.

Klebsiella pneumoniae liver abscess: a new invasive syndrome

Klebsiella pneumoniae is a well known human nosocomial pathogen. Most community-acquired K pneumoniae infections cause pneumonia or urinary tract infections. During the past two decades, however, a distinct invasive syndrome that causes liver abscesses has been increasingly reported in Asia, and this syndrome is emerging as a global disease. In this Review, we summarise the clinical presentation and management as well the microbiological aspects of this invasive disease. Diabetes mellitus and two specific capsular types in the bacterium predispose a patient to the development of liver abscesses and the following metastatic complications: bacteraemia, meningitis, endophthalmitis, and necrotising fasciitis. For patients with this invasive syndrome, appropriate antimicrobial treatment combined with percutaneous drainage of liver abscesses increases their chances of survival. Rapid detection of the hypervirulent strain that causes this syndrome allows earlier diagnosis and treatment, thus minimising the occurrence of sequelae and improving clinical outcomes.

Standardized outpatient management of Klebsiella pneumoniae liver abscesses

OBJECTIVES

Community-acquired Klebsiella pneumoniae has emerged as a major cause of liver abscess in Asia. Using a standardized protocol, we conducted a prospective cohort study of all cases of K. pneumoniae liver abscess treated from 2005 to 2011 at two outpatient parenteral antimicrobial therapy (OPAT) centers in Singapore, to assess the safety and efficacy of treatment.

METHODS

We included all OPAT eligible patients with radiologically confirmed (computed tomography or ultrasound) liver abscesses and K. pneumoniae-positive microbiological cultures obtained from abscess fluid and/or blood at two university teaching hospitals. The endpoints investigated were cure, clinical response, readmission, and mortality.

RESULTS

All 109 patients enrolled in the study successfully completed treatment in OPAT. Nine patients required a short-term readmission due to clinical deterioration. There were no deaths or relapses at 30 days post cessation of antibiotics. Abscess size greater than 5 cm was associated with a delayed clinical response (odds ratio 5.34, 95% confidence interval 1.25-22.91, p = 0.02).

CONCLUSION

The management of K. pneumoniae liver abscesses via OPAT using a standardized protocol is a safe and effective alternative to inpatient intravenous antibiotics.

Risk factors for endogenous endophthalmitis secondary to klebsiella pneumoniae liver abscess: 20-year experience in Southern Taiwan

PURPOSE

To identify the risk factors for endogenous endophthalmitis secondary to Klebsiella pneumoniae liver abscess.

METHODS

We conducted a retrospective review of medical records of 602 patients admitted with K. pneumoniae liver abscess from January 1991 to November 2009. Variables included age, sex, history, month of onset, systemic condition, initial and final visual acuities, slit-lamp biomicroscopy, intraocular pressure, fundus, course and treatment.

RESULTS

Endophthalmitis was identified in 42 patients (53 eyes). Nineteen eyes (35.8%) had final vision of counting fingers or better. Diabetes was significantly associated with the development of endophthalmitis (P = 0.003) and poor visual outcome (P = 0.019). Poor initial vision (worse than counting fingers) was also significantly related to the poor visual outcome of endophthalmitis (P < 0.001). Subgroup analysis of 9 vitrectomy cases showed that progressive anterior chamber reaction might be related to poor visual outcome. Moreover, patients whose disease onset was in winter were slightly more likely to develop endophthalmitis (P = 0.088).

CONCLUSION

Although the prognosis of endogenous K. pneumoniae endophthalmitis is generally poor, some eyes might be saved if treated early enough. Diabetes is a significant risk factor for the development of endogenous endophthalmitis and poor visual outcome in patients with K. pneumoniae liver abscess. Early vitrectomy might be considered in patients whose anterior chamber inflammation did not respond well to intravitreal antibiotics.

Isolation of genes involved in biofilm formation of a Klebsiella pneumoniae strain causing pyogenic liver abscess

BACKGROUND

Community-acquired pyogenic liver abscess (PLA) complicated with meningitis and endophthalmitis caused by Klebsiella pneumoniae is an emerging infectious disease. To investigate the mechanisms and effects of biofilm formation of K. pneumoniae causing PLA, microtiter plate assays were used to determine the levels of biofilm formed by K. pneumoniae clinical isolates and to screen for biofilm-altered mutants from a transposon mutant library of a K. pneumoniae PLA-associated strain.

METHODOLOGY/PRINCIPAL FINDINGS

The biofilm formation of K. pneumoniae was examined by microtiter plate assay. Higher levels of biofilm formation were demonstrated by K. pneumoniae strains associated with PLA. A total of 23 biofilm-decreased mutants and 4 biofilm-increased mutants were identified. Among these mutants, a biofilm-decreased treC mutant displayed less mucoviscosity and produced less capsular polysaccharide (CPS), whereas a biofilm-increased sugE mutant displayed higher mucoviscosity and produced more CPS. The biofilm phenotypes of treC and sugE mutants also were confirmed by glass slide culture. Deletion of treC, which encodes trehalose-6-phosphate hydrolase, impaired bacterial trehalose utilization. Addition of glucose to the culture medium restored the capsule production and biofilm formation in the treC mutant. Transcriptional profile analysis suggested that the increase of CPS production in ΔsugE may reflect elevated cps gene expression (upregulated through rmpA) in combination with increased treC expression. In vivo competition assays demonstrated that the treC mutant strain was attenuated in competitiveness during intragastric infection in mice.

CONCLUSIONS/SIGNIFICANCE

Genes important for biofilm formation by K. pneumoniae PLA strain were identified using an in vitro assay. Among the identified genes, treC and sugE affect biofilm formation by modulating CPS production. The importance of treC in gastrointestinal tract colonization suggests that biofilm formation contributes to the establishment and persistence of K. pneumoniae infection.

Clinical review of endogenous endophthalmitis in Korea: a 14-year review of culture positive cases of two large hospitals

PURPOSE

To identify the clinical features and outcomes of endogenous endophthalmitis in Korea.

MATERIALS AND METHODS

We reviewed 18 patients with endogenous endophthalmitis at 2 Korean hospitals, treated over a 14 year period between January 1993 and December 2006.

RESULTS

The comorbidities observed in these cases were diabetes mellitus and liver cirrhosis. The most common pathogens, which were found in 7 patients each (38.9%), were Klebsiella pneumonia and Pseudomonas aeruginosa. All patients were treated with systemic antibiotics and fortified topical antibiotics. A surgical approach including vitrectomy was performed in 9 cases (50.0%). The prognosis was generally poor, and visual acuity improved slightly in 6 patients (33.3%).

CONCLUSION

In this study, diabetes mellitus and Klebsiella pneumonia showed a close relationship with endogenous endophthalmitis, respectively. Endogenous endophthalmitis is a serious risk to sight and careful attention to establishing the diagnosis and management may decrease the ocular morbidity.

Immune response and pathophysiological features of Klebsiella pneumoniae liver abscesses in an animal model

Capsular serotypes K1 and K2, the rmpA gene (a regulator of the mucoid phenotype) and aerobactin from Klebsiella pneumoniae have been identified as the major virulence factors for pyogenic liver abscesses with high morbidity, mortality and severe complications. The pathological mechanisms remain unclear. In this study, we compared liver immune responses and pathological changes in response to different serotypes of K. pneumoniae infections. A mouse model was used to investigate cytokine and chemokine production, histopathology findings, phagocytic uptake and mortality induced by serotypes K1 (magA(+), rmpA(+), aerobactin(+)), K2 (magA(-), rmpA(+), aerobactin(+)), K62 (magA(-), rmpA(-), aerobactin(-)) and an acapsulated isogenic K1 mutant (ΔK1, magA(+), rmpA(+), aerobactin(+)). K. pneumoniae serotypes K1 and K2 showed lower 50% lethal dose values and more phagocytic resistance to neutrophils than K62 and the ΔK1 mutant. In sequential liver samples, viable bacteria counts increased 3 h to 3 days after low-dose inoculation (<10(1) colony-forming unit (cfu)) with K1 and K2, while K62 and ΔK1 cleared rapidly and became undetectable even with high-dose inoculation (∼2.9 × 10(5) cfu). Time-dependent increases in cytokines and chemokines, including tumor necrosis factor-α, interleukin (IL)-1β, IL-6, IL-10, keratinocyte-derived chemokines and macrophage inflammatory protein-2, were observed in the serum and liver tissue of K1- and K2-infected mice, and severe disease progression manifesting as microabscesses was also identified. K62 and ΔK1 inoculation did not result in similar immune responses and histological changes. These findings illustrate the critical role of phagocytic resistance against innate immunological defense mechanisms as well as its contribution to the development of liver abscesses.

Liver abscess in children: an overview

BACKGROUND

Liver abscess (LA) in the pediatric population has become relatively uncommon in developed countries but it continues to have a high incidence among children in developing countries. This article aims to review the trends in all aspects of LA in children, both temporally and geographically.

DATA SOURCES

The PubMed and Google Scholar database were searched with the keywords "liver abscess", "children", "predisposing causes", "clinical signs and symptoms", "treatment" from 1975 to 2009 and all kinds of retrospective and prospective studies, reviews, case series were included.

RESULTS

Pyogenic LA constitutes the majority of cases, followed by amebic and fungal LA. Staphylococcus aureus is the most common pathogen worldwide. Ultrasonography (US) and computed tomography (CT) are widely used as diagnostic tools. There are varying opinions regarding the treatment of LA in children. The general trend is towards less invasive modalities of treatment like percutaneous drainage along with antimicrobial drug therapy. However, in selected patients, open surgical drainage still plays an important role. The mortality rate for pyogenic LA has shown a decline from about 40% before the 1980s to less than 15% in the recent years. At the same time, the mortality rate of amebic LA cases reported to be around 11%-14% before 1984 has reduced to less than 1% at present.

CONCLUSIONS

Etiological pattern of LA in children has remained the same over the years, and in most regions, it is associated with Staphylococcus aureus and amebic LA is quite uncommon. US or CT scan is the most frequently employed diagnostic modality for LA, and follow-up is usually performed by serial US scans. Antimicrobial therapy along with, if necessary, drainage of the abscess by either percutaneous or open surgical route remains the treatment of choice.

Predictors of septic metastatic infection and mortality among patients with Klebsiella pneumoniae liver abscess

BACKGROUND

Primary liver abscess caused by Klebsiella pneumoniae is an infection that is emerging worldwide and that is associated with severe morbidity and considerable mortality.

METHODS

A retrospective analysis of 110 episodes of primary liver abscess caused by K. pneumoniae that required hospitalization during 2001-2002 was conducted to identify predictors of metastatic infection, mortality, and the efficacy of first-generation cephalosporins and percutaneous drainage. The potential role of Klebsiella rmpA and magA genes was also evaluated.

RESULTS

The study included 59 men and 51 women, with a mean age of 61.8 years. Diabetes was noted in 67 patients (60.9%). Metastatic infection occurred in 17 patients (15.5%), with meningitis accounting for 11 patients (64.7%) and endophthalmitis accounting for 4 patients (23.5%). The overall mortality rate was 10.0% (11 patients). Most of the severe complications occurred within the first 3 days after hospital admission. Ninety-two patients (83.6%) received treatment with cefazolin for >3 days. Four patients (4.3%) of the group who received cefazolin had metastatic infection, 1 patient (1.1%) experienced septic shock, and 3 (3.3%) experienced acute respiratory failure. Five (5.4%) of those 92 patients died. Multivariable analysis revealed that rmpA (odds ratio [OR], 28.85), Acute Physiologic and Chronic Health Evaluation (APACHE) II score >or=20 (OR, 8.08), and septic shock (OR, 4.33) were statistically significant predictors of metastatic infection. Metastatic infection (OR, 6.73), severity of disease (APACHE II score >or=16; OR, 11.82), septic shock (OR, 8.30), acute respiratory failure (OR, 69.92), and gas formation revealed on imaging (OR, 13.26) predicted mortality. Pigtail drainage protected against both metastatic infection (OR, 0.25) and mortality (OR, 0.14).

CONCLUSION

Management of primary liver abscess caused by K. pneumoniae with use of first-generation cephalosporins and percutaneous drainage was associated with low rates of mortality, metastatic infection, and complications. These rates are comparable to those reported for third-generation cephalosporins.

Capsular serotype K1 or K2, rather than magA and rmpA, is a major virulence determinant for Klebsiella pneumoniae liver abscess in Singapore and Taiwan

Capsular serotypes, magA, and rmpA have been documented in high prevalence for Klebsiella pneumoniae liver abscess. To investigate the regional difference and the correlation of capsular serotype, magA, and rmpA with virulence, 73 isolates were collected in Singapore and Taiwan. Capsular serotypes were determined by countercurrent immunoelectrophoresis, the presence of magA and rmpA was determined by PCR, and virulence was determined by phagocytosis and mouse inoculation. Isolates from Singapore were similar to those from Taiwan in genomic heterogeneity, prevalence of serotype, and the presence of magA and rmpA. The most common serotype was K1 (34/73; 46.6%), followed by K2 (15/73; 20.5%). magA was restricted to serotype K1. All K1 or K2 isolates and 66.7% (16/24) of isolates that were neither serotype K1 nor serotype K2 (non-K1/K2) carried rmpA. Serotype K1 or K2 isolates demonstrated significantly more phagocytic resistance and virulence than did rmpA-positive and -negative groups of non-K1/K2 isolates. In the non-K1/K2 group, the virulence profiles of rmpA-positive strains from Taiwan and Singapore were different by phagocytosis assay and in the mouse model, indicating that factors other than rmpA contributed to virulence. The characteristics of K. pneumoniae liver abscess in Singapore and Taiwan are similar. Capsular serotype K1 or K2 plays a more important role than magA and rmpA in determining virulence in K. pneumoniae liver abscess.

Impaired phagocytosis of capsular serotypes K1 or K2 Klebsiella pneumoniae in type 2 diabetes mellitus patients with poor glycemic control

CONTEXT

Diabetes mellitus (DM) and capsular serotypes K1 and K2 Klebsiella pneumoniae have been identified as risk factors for liver abscess and complicated endophthalmitis.

OBJECTIVE

The objective of this study was to determine whether poor glycemic control contributes to the development of capsular serotype K1 or K2 K. pneumoniae liver abscess.

DESIGN AND SETTING

Neutrophil phagocytosis in patients with type 2 DM and nondiabetic controls was compared with isolates from liver abscess. Phagocytic rates of 18 K1/K2 and nine non-K1/K2 K. pneumoniae strains were evaluated by flow cytometry and electron microscopy. PATIENTS OR STUDY PARTICIPANTS: Forty patients with type 2 diabetes, 14 with good glycemic control, 26 with poor glycemic control, and 13 age-matched healthy normal subjects, were studied.

MAIN OUTCOME MEASURES

Phagocytic rate of K. pneumoniae was measured.

RESULTS

Phagocytosis of serotype K1/K2 isolates by neutrophils from diabetics was significantly less than normal controls (P < 0.01). Further analysis revealed that, in type 2 DM patients with poor glycemic control, phagocytosis of K1/K2 was remarkably impaired at 10 min (25.2 +/- 1.7 vs. 42.4 +/- 1.8%) and persisted until 60 min (51 +/- 1.2 vs. 59.4 +/- 1.4%; P < 0.01), but in type 2 DM patients with good glycemic control were similar at 10 min (38.2 +/- 1.7% vs. 42.4 +/- 1.8%) and at 60 min (57 +/- 0.3% vs. 59.4 +/- 1.4%; P = 0.2). No significant difference in the phagocytosis of non-K1/K2 K. pneumoniae among all subjects was observed.

CONCLUSIONS

Poor glycemic control plays a role in impairing neutrophil phagocytosis of K1/K2 K. pneumoniae, but does not significantly affect the phagocytosis of non-K1/K2 K. pneumoniae. This study identifies poor glycemic control as a risk factor for susceptibility to serotype K1/K2 K. pneumoniae liver abscess and complicated endophthalmitis.

Septic Monoarthritis and Osteomyelitis in an Elderly Man Following Klebsiella pneumoniae Genitourinary Infection: Case Report

Introduction: Klebsiella pneumoniae septic arthritis and osteomyelitis, albeit uncommon in adults, are important sites of disseminated infection. Many case reports have shown K. pneumoniae as a cause of nosocomial transmitted septic arthritis in neonates and children. We report a rare case of an elderly patient with K. pneumoniae genitourinary infection spreading to the liver and other extra hepatic sites like the prostate and peripheral joint. Clinical Picture: The patient presented with a short history of general malaise, fever and urinary symptoms, associated with an acute monoarthritis of the ankle. On admission, he was in septic shock. Investigations suggested an infective cause, as evidenced by raised total white cell count and pyuria. K. pneumoniae was cultured from both urine and ankle synovial fluid. Imaging confirmed multiple liver and prostatic abscesses, as well as osteomyelitis of the foot bones adjacent to the ankle. Treatment: Treatment in this case included surgical drainage of the affected joint and surrounding soft tissue structures, in addition to a 6-week course of systemic antibiotics. Outcome: The patient had good clinical response following treatment. In addition, we noted a normalisation of his laboratory parameters and resolution of the intraabdominal and pelvic abscesses. Conclusion: This case emphasises the importance of timely and accurate diagnosis followed by appropriate treatment in disseminated K. pneumoniae infection to prevent significant morbidity and mortality. Key words: Arthritis, Infectious, Klebsiella infections, Liver abscess

Pyogenic liver abscess with a focus on Klebsiella pneumoniae as a primary pathogen: an emerging disease with unique clinical characteristics

OBJECTIVES

Pyogenic liver abscess is a common intraabdominal infection. Historically, Escherichia coli (E. coli) has been the predominant causative agent. Klebsiella liver abscess (KLA) was first reported in Taiwan and has surpassed E. coli as the number one isolate from patients with hepatic abscesses in that country and reports from other countries, including the United States, have increased. We examined the microbiologic trends of pyogenic liver abscess at our institution to determine if a similar shift in etiologic agents was occurring.

METHODS

We examined all cases of liver abscess at our institution from 1999 to 2003 via a retrospective chart review of inpatient records and reviewed the English literature via a MEDLINE search for all U.S. cases of KLA.

RESULTS

Since 1966, only 12 cases of KLA have been reported in the United States. We report six cases of KLA at our institution alone; 2 patients were not Asian, and 4 were not diabetic. Klebsiella pneumoniae (K. pneumoniae) was the most common cause of pyogenic hepatic abscess at our institution over the last 5-yr period. When comparing Klebsiella versus other causes of pyogenic liver abscess, there were no significant differences in demographics or laboratory findings; however, most of our Klebsiella cases occurred among Filipinos. Review of the 18 cases of K. pneumoniae liver abscess in the United States showed that Klebsiella cases occurred predominantly among middle-aged men; 83% had concurrent bacteremia and 28% had metastatic complications. An increasing number of cases were reported from the United States since the mid-1990s.

CONCLUSIONS

These data suggest that KLA may represent an emerging disease in Western countries, such as the United States. The diagnosis of K. pneumoniae should be considered in all cases of liver abscess, and appropriate antibiotic therapy and a diagnostic work-up for metastatic complications should be employed.

Isolation of a chromosomal region of Klebsiella pneumoniae associated with allantoin metabolism and liver infection

Klebsiella pneumoniae liver abscess with metastatic complications is an emerging infectious disease in Taiwan. To identify genes associated with liver infection, we used a DNA microarray to compare the transcriptional profiles of three strains causing liver abscess and three strains not associated with liver infection. There were 13 clones that showed higher RNA expression levels in the three liver infection strains, and 3 of these 13 clones contained a region that was absent in MGH 78578. Sequencing of the clones revealed the replacement of 149 bp of MGH 78578 with a 21,745-bp fragment in a liver infection strain, NTUH-K2044. This 21,745-bp fragment contained 19 open reading frames, 14 of which were proven to be associated with allantoin metabolism. The K2044 (DeltaallS) mutant showed a significant decrease of virulence in intragastric inoculation of BALB/c mice, and the prevalence of this chromosomal region was significantly higher in strains associated with liver abscess than in those that were not (19 or 32 versus 2 of 94; P = 0.0001 [chi(2) test]). Therefore, the 22-kb region may play a role in K. pneumoniae liver infection and serve as a marker for rapid identification.

Extended-spectrum cephalosporin compared to cefazolin for treatment of Klebsiella pneumoniae-caused liver abscess

From January 1995 to May 2000, a total of 107 adults with liver abscess due to Klebsiella pneumoniae admitted at a large medical center in northern Taiwan were reviewed. Patients were considered to have received cefazolin or an extended-spectrum cephalosporin if they received at least 3 days of that antibiotic within the first 5 days of hospitalization. Fifty-nine (55.1%) patients received cefazolin, and 48 (44.9%) patients received an extended-spectrum cephalosporin. The demographic data, clinical features, severities of illness, and rates of early drainage for the two groups were comparable. However, the rates of developing complications for the two groups were significantly different (37.3 versus 6.3%, respectively; P < 0.001). Furthermore, six independent factors preventing severe complications following liver abscess due to K. pneumoniae were identified: normal platelet count, alkaline phosphatase less than 300 U/liter, no gas formation in the abscess, APACHE III score less than 40, use of an extended-spectrum cephalosporin, and early drainage. In conclusion, cefazolin therapy may be suboptimal for patients with liver abscess due to K. pneumoniae despite active in vitro susceptibility. Use of an extended-spectrum cephalosporin and early drainage for patients with liver abscess due to K. pneumoniae are suggested.

A global emerging disease of Klebsiella pneumoniae liver abscess: is serotype K1 an important factor for complicated endophthalmitis?

BACKGROUND AND AIMS

Over the past two decades in Taiwan, pyogenic liver abscess has usually been caused by a single microorganism, Klebsiella pneumoniae, and is frequently associated with the serious complication of endophthalmitis, especially in diabetic patients. However, the relationship between the clinical presentation and bacterial factors remains unclear. The aim of this study was to investigate the clinical features of patients and the serotype and ribotype of K pneumoniae liver abscess.

METHODS

From July 1991 to June 1998, a total of 134 cases of K pneumoniae liver abscess with 248 K pneumoniae isolates from the same patients were collected from two large medical centres in northern Taiwan. Clinical data were collected from medical records. Serotyping and ribotyping were performed using the countercurrent immunoelectrophoresis method and automated Riboprinter.

RESULTS

Serotyping revealed that the most common serotypes were K1 (63.4%) and K2 (14.2%). K1 isolates occurred at a significantly higher frequency (p<0.01) than all other serotypes. Among 134 patients, 105 (78.4%) had suffered from diabetes mellitus for 3-15 years. Fourteen patients (10.4%) had metastatic infection to the eye causing septic endophthalmitis. Liver aspirates, and blood and vitreous pus cultures yielded the same serotype of K pneumoniae in all patients. Among patients with septic endophthalmitis, 92.3% (13/14) were diabetic, and 85.7% (12/14) of the isolates belonged to serotype K1. For molecular typing, different degrees of genetic polymorphism among isolates with the same K1 serotype suggested no particular prevalence of any one strain in K pneumoniae liver abscess.

CONCLUSION

K pneumoniae serotype K1 was significantly associated with liver abscess and the complication of endophthalmitis, especially in diabetic patients. Physicians should request an immediate report of serotyping and susceptibility test results simultaneously if a diagnosis of pyogenic liver abscess has been made so that early and appropriate management for possible complications will not be delayed. The use of ceftriaxone because of its higher concentration in the aqueous humor is suggested to decrease the chance of septic endophthalmitis.

Community-acquired Klebsiella pneumoniae bacteremia: global differences in clinical patterns

We initiated a worldwide collaborative study, including 455 episodes of bacteremia, to elucidate the clinical patterns of Klebsiella pneumoniae. Historically, community-acquired pneumonia has been consistently associated with K. pneumoniae. Only four cases of community-acquired bacteremic K. pneumoniae pneumonia were seen in the 2-year study period in the United States, Argentina, Europe, or Australia; none were in alcoholics. In contrast, 53 cases of bacteremic K. pneumoniae pneumonia were observed in South Africa and Taiwan, where an association with alcoholism persisted (p=0.007). Twenty-five cases of a distinctive syndrome consisting of K. pneumoniae bacteremia in conjunction with community-acquired liver abscess, meningitis, or endophthalmitis were observed. A distinctive form of K. pneumoniae infection, often causing liver abscess, was identified, almost exclusively in Taiwan.

Liver abscess caused by Klebsiella pneumoniae in siblings

Klebsiella pneumoniae has been emerging as the leading cause of liver abscess in diabetic patients. Results of molecular typing of K. pneumoniae isolates from two siblings with liver abscess, their family members, and the environment suggest a possibility of cross infection of liver abscess by the fecal-oral route within diabetic patients.

Amebic liver abscess

Amebiasis is a widespread parasitic disease caused by Entamoeba histolytica. This protozoan organism is the third leading parasitic cause of death in the developing world and is an important health risk to travelers in endemic areas. Amebiasis most commonly results in asymptomatic colonization of the gastrointestinal tract, but some patients may develop intestinal invasive disease or extraintestinal disease-amebic liver abscess being the most common extraintestinal manifestation. This article reviews epidemiologic features, pathophysiology, clinical features, diagnostic tests, imaging studies, treatment of amebic liver abscess, and prevention measures.

Abscessos hepáticos piogênicos: emprego dos recursos diagnósticos e terapêuticos

A evolução tecnológica dos recursos diagnósticos e terapêuticos das últimas décadas tem possibilitado mudanças no manejo de pacientes com abscessos hepáticos piogênicos (AHP). A abordagem cirúrgica tem sido substituída ou complementada com os métodos de punção guiados por tomografia computadorizada (TC) ou por ultra-sonografia (US). Foi realizado um estudo retrospectivo de 27 casos de AHP atendidos num período de 15 anos, objetivando principalmente avaliar os métodos diagnósticos e terapêuticos utilizados em nosso hospital neste período, comparando a nossa realidade com os dados da literatura mundial. Dor abdominal (96%), febre (92%), e hepatomegalia (85%) foram os sinais e sintomas mais comuns; leucocitose (85%) com aumento dos bastões (88%), hipoalbuminemia (77%) e elevação da fosfatase alcalina (66%) foram as alterações laboratoriais mais freqüentes. Escherichia coli e Staphylococcus sp foram os agentes mais comumente identificados. A US abdominal foi o exame de eleição, fazendo diagnóstico em 92% dos casos, e a TC foi utilizada em 44% dos pacientes, complementar à US. Cinco pacientes (19%) foram tratados por punção com inserção de catéter de drenagem dirigida por US, enquanto 16 (59%) foram submetidos a laparotomia para drenagem e seis (22%) foram tratados apenas com antibioticoterapia. Sepse (37%) e derrame pleural (19%) foram as complicações mais freqüentes. Houve três óbitos (mortalidade de 11 %). Os métodos de drenagem percutânea apresentam menor morbidade que a drenagem cirúrgica em relação ao procedimento, diminuindo o risco de contaminação da cavidade peritoneal, além de apresentarem bons e similares resultados. A citologia do material aspirado possibilita também a complementação diagnóstica, principalmente para doenças subjacentes, facilitando a identificação da etiologia dos AHP. A drenagem por videolaparoscopia pode constituir outra alternativa à drenagem cirúrgica, com a vantagem da identificação dos abscessos não acessíveis à drenagem percutânea, mas apresentando ainda o risco de contaminação da cavidade peritoneal. Portanto, a indicação de drenagem por laparotomia para pacientes portadores de AHP deveria restringir-se àqueles onde houve falha na drenagem percutânea ou impossibilidade de acesso aos abscessos, principalmente no caso de abscessos múltiplos, e quando houver ruptura do abscesso ou grave comprometimento do estado geral do paciente. É necessário oferecer ao paciente o melhor tratamento de acordo com os recursos disponíveis do hospital, permitindo assim a diminuição das taxas de morbidade e mortalidade para esta doença.