Clinical and Molecular Characteristics of Emerging Hypervirulent Klebsiella pneumoniae Bloodstream Infections in Mainland China

Abstract

c Recently, the newly emerged hypervirulent Klebsiella pneumoniae strain (hvKP) has caused great concern globally, but the clinical features and molecular characteristics of bacteremia caused by hvKP are rarely reported in mainland China. Seventy patients with K. pneumoniae bacteremia were investigated to study the clinical features of hvKP infection from 2008 till 2012 in Beijing Chao-Yang Hospital. The molecular characteristics of the hvKP strains were also studied using PCR, multilocus sequence typing, and pulsed-field gel electrophoresis (PFGE) methods. hvKP was identified in 31.4% of the patients with K. pneumoniae bacteremia, which displayed 4 serotypes (K1, K2, K20, and K57). Patients with hvKP infection tended to have no underlying diseases compared to those with classic K. pneumoniae (cKP). More hvKP-positive patients (95.5%) had community-acquired infection than did cKP-infected patients (35.4%) (P < 0.001). The 30-day mortality rate was lower in hvKP-infected patients than in cKPinfected patients (4.5% compared to 16.7%). Resistance to tested antimicrobials was significantly greater in cKP-than in hvKPinfected patients. Two extended-spectrum-beta-lactamase (ESBL)-producing hvKP strains were found. Seven novel sequence types (STs) and 4 new alleles of K. pneumoniae were revealed. A strong correlation was found between two STs (ST23, ST1265) and the K1 serotype. The hvKP isolates (n ‫؍‬ 22) had 14 different PFGE patterns, and among them 10 K1 isolates shared similar PFGE patterns. The emerging hvKP strain was prevalent in patients with severe community-acquired infections in healthy individuals in China. Identification of ESBL-producing hvKP strains in hvKP-infected patients will facilitate clinical management of hvKP infection.

Microbiological characteristics of hypermucoviscous Klebsiella pneumoniae isolates from different body fluids

“…We identified hvKP more frequently in urine and abscess, and less frequently in blood, tracheal secretion, and bile than another similar large hospital in China [26]. Most community-acquired infections were blood infections or a presence of different abscess, similar to previous reports [12,16,27]. Out of all, 40% (6/15) hvKP infections in nonblood/abscess group were defined as hospital-acquired versus 11.1% (1/9) in blood/abscess group.…”

“…An exception to this finding was the presence of carbapenem resistance identified in hvKP isolated from tracheal secretions and urine of patients in Group 1 [12,26]. These two isolates were characterized as K2/ST25 and K2/ST65 with blaKPC-2, respectively.…”

“…All samples were stored at −80°C prior to genetic and virulence testing. An hv phenotype test was performed on all isolates to distinguish hvKP from classic K. pneumoniae (cKP) [12]. The presence of a viscous string greater than 5 mm in length with a bacteriology inoculation loop on bacterial cultures grown overnight on 5% sheep blood agar plate at 37°C was regarded as diagnostic of hvKP.…”

“…hvKP is considered to be more virulent than hv-negative strains and this phenotype is commonly found in K. pneumoniae strains which cause CA-PLA and BSI [8,12,13]. More importantly, they exhibit a higher tendency to metastatic spread.…”

Genomic analysis of diversity, population structure, virulence, and antimicrobial resistance in Klebsiella pneumoniae , an urgent threat to public health

“…The presence of yersiniabactin in CC258, and also in the ESBL clones ST14 and ST15, is worrying, because our data show that it not only is strongly associated with infection in humans but also appears to be a frequent first step in the acquisition of additional siderophores that augment the ability of KpI clones to cause invasive non-hospital-related infections. There also is a high risk that current hypervirulent clones may acquire AMR, and MDR ST23 already has been reported in Korea, Vietnam, China, Madagascar, and Brazil (12,(61)(62)(63). Now that the associations have been recognized, new efforts can be more focused on the task of reconstructing the mobile elements that carry the critical virulence genes, ideally using long-read sequencing approaches that have proven successful for unraveling MDR plasmids (64).…”