Kuo-Ming Yeh

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.

Capsular Serotype K1 or K2, Rather than magA and rmpA, Is a Major Virulence Determinant for Klebsiella pneumoniae Liver Abscess in Singapore and Taiwan

ABSTRACT 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.

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

ABSTRACT 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 <102 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.

National surveillance study on carbapenem non-susceptible Klebsiella pneumoniae in Taiwan: the emergence and rapid dissemination of KPC-2 carbapenemase

Objectives The global spread and increasing incidence of carbapenem non-susceptible Klebsiella pneumoniae (CnSKP) has made its treatment difficult, increasing the mortality. To establish nationwide data on CnSKP spread and carbapenem-resistance mechanisms, we conducted a national surveillance study in Taiwanese hospitals. Methods We collected 100 and 247 CnSKP isolates in 2010 and 2012, respectively. The tests performed included antibiotic susceptibility tests; detection of carbapenemase, extended-spectrum β-lactamases (ESBL), and AmpC β-lactamases genes; outer membrane porin profiles; and genetic relationship with pulsed-field gel electrophoresis and multilocus sequence type. Results The resistance rate of CnSKP isolates to cefazolin, cefotaxime, cefoxitin, ceftazidime, and ciprofloxacin was over 90%. Susceptibility rate to tigecycline and colistin in 2010 was 91.0% and 83.0%, respectively; in 2012, it was 91.9% and 87.9%, respectively. In 2010, carbapenemase genes were detected in only 6.0% of isolates (4 bla IMP-8 and 2 bla VIM-1). In 2012, carbapenemase genes were detected in 22.3% of isolates (41 bla KPC-2, 7 bla VIM-1, 6 bla IMP-8, and 1 bla NDM-1). More than 95% of isolates exhibited either OmpK35 or OmpK36 porin loss or both. Impermeability due to porin mutation coupled with AmpC β-lactamases or ESBLs were major carbapenem-resistance mechanisms. Among 41 KPC-2-producing K. pneumoniae isolates, all were ST11 with 1 major pulsotype. Conclusions In 2010 and 2012, the major mechanisms of CnSKP in Taiwan were the concomitance of AmpC with OmpK35/36 loss. KPC-2-KP dissemination with the same ST11 were observed in 2012. The emergence and rapid spread of KPC-2-KP is becoming an endemic problem in Taiwan. The identification of NDM-1 K. pneumoniae case is alarming.

Klebsiella pneumoniae in gastrointestinal tract and pyogenic liver abscess.

To determine the role of gastrointestinal carriage in Klebsiella pneumoniae liver abscess, we studied 43 patients. Bacterial isolates from liver and fecal samples from 10 patients with this condition and 7 healthy carriers showed identical serotypes and genotypes with the same virulence. This finding indicated that gastrointestinal carriage is a predisposing factor for liver abscess.

Seroepidemiology of Klebsiella pneumoniae colonizing the intestinal tract of healthy chinese and overseas chinese adults in Asian countries

BackgroundCapsular serotypes K1 and K2 of Klebsiella pneumoniae are thought to the major virulence determinants responsible for liver abscess. The intestine is one of the major reservoirs of K. pneumoniae, and epidemiological studies have suggested that the majority of K. pneumoniae infections are preceded by colonization of the gastrointestinal tract. The possibility of fecal-oral transmission in liver abscess has been raised on the basis of molecular typing of isolates. Data on the serotype distribution of K. pneumoniae in stool samples from healthy individuals has not been previously reported. This study investigated the seroepidemiology of K. pneumoniae isolates from the intestinal tract of healthy Chinese in Asian countries. Stool specimens from healthy adult Chinese residents of Taiwan, Japan, Hong Kong, China, Thailand, Malaysia, Singapore, and Vietnam were collected from August 2004 to August 2010 for analysis.ResultsSerotypes K1/K2 accounted for 9.8% of all K. pneumoniae isolates from stools in all countries. There was no significant difference in the prevalence of K1/K2 isolates among the countries excluding Thailand and Vietnam. The antimicrobial susceptibility pattern was nearly the same in K. pneumoniae isolates. The result of pulsed-field gel electrophoresis revealed no major clonal cluster of serotype K1 isolates.ConclusionsThe result showed that Chinese ethnicity itself might be a major factor predisposing to intestinal colonization by serotype K1/K2 K. pneumoniae isolates. The prevalent serotype K1/K2 isolates may partially correspond to the prevalence of K. pneumoniae liver abscess in Asian countries.

Experience of using convalescent plasma for severe acute respiratory syndrome among healthcare workers in a Taiwan hospital

Abstract Objectives: To describe the immunological responses and clinical outcome of coronavirus (SARS) infected healthcare workers (HCW) who had been administered with convalescent plasma as a treatment. Methods: Convalescent plasma (500 mL) was obtained from each of three SARS patients and transfused into the three infected HCW. Donors were blood type O and seronegative for hepatitis B and C, HIV, syphilis and human T-cell lymphotropic virus types I and II (HTLV-I and -II). Serum antibody (IgG) titre was >640. Apharesis was performed with a CS 3000 plus cell separator followed by the forming of the convalescent phase plasma. As part of the routine check with donated plasma, the convalescent plasma was confirmed free of residual SARS-CoV by RT–PCR. Serial serum samples obtained from the recipients of the convalescent plasma were collected to undertake real-time quantitative RT–PCR for SARS-CoV for direct measurement of viral concentration. Specific immunoglobulin IgM and IgG concentrations were titrated using an antigen microarray developed in-house. Results: Viral load dropped from 495 × 103, 76 × 103 or 650 × 103 copies/mL to zero or 1 copy/mL one day after transfusion. Anti-SARS-CoV IgM and IgG also increased in a time-dependent manner following transfusion. All three patients survived. One HCW became pregnant subsequently, delivering 13 months after discharge. Positive anti-SARS-CoV IgG was detected in the newborn. Passive transfer of anti-SARS-CoV antibody from the mother was considered as a possibility. Conclusions: All infected HCW whose condition had progressed severely and who had failed to respond to the available treatment, survived after transfusion with convalescent plasma.

Impact of extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae on the outcome of community-onset bacteremic urinary tract infections.

BACKGROUND/PURPOSE The number of community-onset bacteremic urinary tract infections (UTIs) caused by Escherichia coli and Klebsiella pneumoniae is increasing. However, the impact of extended-spectrum β-lactamase (ESBL)-producing E. coli and K. pneumoniae (ESBL-EK) on bacteremic UTI outcomes is unknown. The aim of this study was to retrospectively analyze the impact of ESBL-EK on community-onset bacteremic UTIs. METHODS Of the 58 patients enrolled, 12 suffered from ESBL-EK-caused community-onset bacteremic UTIs. Patients were categorized into ESBL (n=12) and non-ESBL (n=46) groups. Diagnosis was based on findings of concurrent bacteremia and bacteriuria caused by the same pathogen on admission. RESULTS The ESBL group had significantly more male patients (66.7%vs. 23.9%; p=0.005), indwelling urinary catheters (41.7%vs. 6.5%; p=0.002), patients admitted from other healthcare facilities (50.0%vs. 8.7%; p=0.001), and patients with higher Acute Physiology and Chronic Health Evaluation II scores (23.3±7.1 vs. 15.9±6.3; p=0.001) and intensive care unit admissions (41.7%vs. 4.4%; p=0.003) than the non-ESBL group. Multiple logistic regression analysis revealed that male gender (odds ratio=9.2; 95%, confidence interval=1.7-50.6) and healthcare facility residency (odds ratio=15.5; 95% confidence interval=2.4-98.9) were independent risk factors for ESBL-producer infections among bacteremic UTIs. Although the mortality rate of both groups was similar (8.3%vs. 4.4%; p=0.403), the ESBL group had longer hospital stays (16.3±9.3 days vs. 7.9±5.2 days; p=0.010) and higher antibiotic costs (615.1±423.5 USD vs. 252.8±269.2 USD, p=0.014). CONCLUSION Male gender and healthcare facility residency are risk factors for ESBL-producer infections among patients with community-onset bacteremic UTIs. Patients with bacteremic UTIs caused by ESBL-EK also have prolonged hospital stays and higher antibiotic costs. Early detection of ESBLs and appropriate antibiotic coverage are likely to shorten hospital stays and reduce medical costs.

Community-Acquired Liver Abscess Caused by Serotype K1 Klebsiella pneumoniae with CTX-M-15-Type Extended-Spectrum β-Lactamase

Klebsiella pneumoniae has emerged as the leading cause of community-acquired pyogenic liver abscess in many countries. Community-acquired pyogenic liver abscess due to K. pneumoniae with a unique antibiogram indicative of resistance only to ampicillin has been demonstrated. We reported the first

Recurrent Klebsiella pneumoniae Liver Abscess: Clinical and Microbiological Characteristics

ABSTRACT Recurrent Klebsiella pneumoniae liver abscesses (KLAs) are rarely reported. Six cases of recurrent KLAs are characterized. Most of the patients had diabetes and K1 serotype KLAs. All of the isolates were uniformly susceptible to cefazolin. Distinct molecular fingerprints were found for the strains isolated from both primary and recurrent KLAs.