BackgroundKlebsiella pneumoniae bacteremia is a major cause of morbidity and mortality worldwide. We aimed to compare the clinical characteristics, distribution of capsular types, and antimicrobial resistance of K. pneumoniae bacteremia among community-acquired (CA), healthcare-associated (HCA), and nosocomial infections.MethodsThis retrospective study of patients with K. pneumoniae bacteremia was conducted at Taipei Veterans General Hospital from January to December 2015. Clinical characteristics of K. pneumoniae bacteremia were collected. The K. pneumoniae isolates were subjected to antimicrobial susceptibility testing and capsular genotyping.ResultsIn total, 337 patients with K. pneumoniae bacteremia were identified: 70 (20.8%), 102 (30.3%), and 165 (48.9%) presented with CA, HCA, and nosocomial infection, respectively. The 28-day mortality of HCA bacteremia was lower than that of nosocomial bacteremia (17.6% versus 30.9%, p = 0.016); however, that of the HCA and CA bacteremia was similar (17.6% versus 14.3%, p = 0.557). CA isolates had the highest prevalence of virulent capsular types (51.4%), followed by HCA (36.3%) and nosocomial isolates (19.4%). The proportion of multidrug-resistant (MDR) isolates was highest in nosocomial infections (41.8%), followed by HCA (23.5%) and CA infections (5.7%).ConclusionCA, HCA and nosocomial K. pneumoniae are distinct entities, as evidenced by the differences in clinical characteristics, antimicrobial resistance, and capsular types found in this study.
Background: We aimed to compare the clinical characteristics of patients with community-acquired pneumonia (CAP), healthcare-associated pneumonia (HCAP), and hospital-acquired pneumonia (HAP) caused by Klebsiella pneumoniae and analyze the antimicrobial resistance and proportion of hypervirluent strains of the microbial isolates. Methods: We conducted a retrospective study on patients with pneumonia caused by K. pneumoniae at the Taipei Veterans General Hospital in Taiwan between January 2014 and December 2016. To analyze the clinical characteristics of these patients, data was extracted from their medical records. K. pneumoniae strains were subjected to antimicrobial susceptibility testing, capsular genotyping and detection of the rmpA and rmpA2 genes to identify hypervirulent strains. Results: We identified 276 patients with pneumonia caused by K. pneumoniae, of which 68 (24.6%), 74 (26.8%), and 134 (48.6%) presented with CAP, HCAP, and HAP, respectively. The 28-day mortality was highest in the HAP group (39.6%), followed by the HCAP (29.7%) and CAP (27.9%) groups. The HAP group also featured the highest proportion of multi-drug resistant strains (49.3%), followed by the HCAP (36.5%) and CAP groups (10.3%), while the CAP group had the highest proportion of hypervirulent strains (79.4%), followed by the HCAP (55.4%) and HAP groups (41.0%). Conclusion: Pneumonia caused by K. pneumoniae was associated with a high mortality. Importantly, multi-drug resistant strains were also detected in patients with CAP. Hypervirulent strains were prevalent in all 3 groups of pneumonia patients, even in those with HAP.
A rise in tigecycline resistance in Klebsiella pneumoniae has been reported recently worldwide. We sought to identify risk factors, outcomes, and mechanisms for adult patients with tigecycline-nonsusceptible K. pneumoniae bacteremia in Taiwan. We conducted a matched case-control study (ratio of 1:1) in a medical center in Taiwan from January 2011 through June 2015. The cases were patients with tigecycline-nonsusceptible K. pneumoniae bacteremia, and the controls were patients with tigecyclinesusceptible K. pneumoniae bacteremia. Logistic regression was performed to evaluate the potential risk factors for tigecyclinenonsusceptible K. pneumoniae bacteremia. Quantitative reverse transcription-PCR was performed to analyze acrA, oqxA, ramA, rarA, and kpgA expression among these isolates. A total of 43 cases were matched with 43 controls. The 14-day mortality of patients with tigecycline-nonsusceptible K. pneumoniae bacteremia was 30.2%, and the 28-day mortality was 41.9%. The attributable mortalities of tigecycline-nonsusceptible K. pneumoniae at 14 and 28 days were 9.3 and 18.6%, respectively. Fluoroquinolone use within 30 days prior to bacteremia was the only independent risk factor for tigecycline-nonsusceptible K. pneumoniae bacteremia. The tigecycline-nonsusceptible K. pneumoniae bacteremia was mostly caused by overexpression of AcrAB and/or OqxAB efflux pumps, together with the upregulation of RamA and/or RarA, respectively. One isolate demonstrated isolated overexpression of kpgA. In conclusion, tigecycline-nonsusceptible K. pneumoniae bacteremia was associated with high mortality, and prior fluoroquinolone use was the independent risk factor for the acquisition of tigecycline-nonsusceptible K. pneumoniae. The overexpression of AcrAB and/or OqxAB contributes to tigecycline nonsusceptibility in K. pneumoniae.
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