title: Clinical features and molecular epidemiology of plasmid-mediated DHA-type AmpC β-lactamase-producing Klebsiella pneumoniae blood culture isolates, Hong Kong.
abstract: Knowledge of risk factors and clinical characteristics of bacteraemia caused by plasmid-mediated AmpC β-lactamase (pAmpC)-producing Klebsiella pneumoniae (pAmpC-Kp) is not well described. This was a retrospective cohort study of patients with K. pneumoniae bacteraemia in three Hong Kong regional hospitals. Demographic and clinical data were retrieved from medical records. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were performed for molecular epidemiology. A total of 109 patients were included, divided into four groups: bacteraemia due to K. pneumoniae with (i) DHA-type pAmpC (n=23), (ii) extended-spectrum β-lactamase (ESBL) (n=37), (iii) DHA-type pAmpC+ESBL (n=26) and (iv) controls (n=23). Nursing home residence was independently associated with pAmpC-Kp bacteraemia compared with ESBL-Kp bacteraemia [adjusted odds ratio (aOR)=7.13, 95% confidence interval (CI) 1.36-37.54] and controls (aOR=41.47, 95% CI 4.55-377.75). Compared with controls, patients with pAmpC-Kp bacteraemia also suffered from more severe illness [median Acute Physiology and Chronic Health Evaluation (APACHE) II scores 16 and 25, respectively; P=0.006]. Importantly, the pAmpC group received discordant empirical antimicrobial therapy more frequently (OR=24.00, 95% CI 5.01-114.97), resulting in higher 7-day mortality (OR=20.17, 95% CI 2.32-175.67) and 30-day mortality (OR 4.68, 95% CI 1.29-16.98). PFGE detected six pulsotypes, corresponding to the predominant sequence type 11. Severity of illness and mortality of patients with bacteraemia caused by pAmpC-Kp were high. Patients who are nursing home residents presenting nosocomial sepsis should be treated with broad-spectrum antimicrobials.
authors: Microbiology, Department of Pathology, Princess Margaret Hospital, Hong Kong. Electronic address: sluk@ha.org.hk.
authors: Shik
authors: S
authors: Luk
authors: Microbiology, Department of Pathology, Princess Margaret Hospital, Hong Kong.
authors: Wing-Kin
authors: WK
authors: Wong
authors: Microbiology, Department of Pathology, Princess Margaret Hospital, Hong Kong.
authors: Alex Yat-Man
authors: AY
authors: Ho
authors: Infectious Disease Control Training Centre, Hospital Authority, Hong Kong.
authors: Kelvin Chung-Ho
authors: KC
authors: Yu
authors: Microbiology, Department of Pathology, Princess Margaret Hospital, Hong Kong.
authors: Wing-Kin
authors: WK
authors: To
authors: Microbiology, Department of Pathology, Princess Margaret Hospital, Hong Kong.
authors: Tak-Keung
authors: TK
authors: Ng
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001426:Bacterial Proteins / Q000235:genetics*; D000071997:Blood Culture; D005260:Female; D006723:Hong Kong; D006801:Humans; D007710:Klebsiella Infections / Q000382:microbiology*; D007711:Klebsiella pneumoniae / Q000201:enzymology / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D058885:Multilocus Sequence Typing; D009735:Nursing Homes; D010957:Plasmids / Q000235:genetics; D012189:Retrospective Studies; D012307:Risk Factors; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; C048795:AmpC beta-lactamases; D001618:beta-Lactamases
keywords: Bacteraemia; Clinical features; Hong Kong; Klebsiella pneumoniae; Molecular epidemiology; Plasmid-mediated AmpC β-lactamase