Differential host susceptibility and bacterial virulence factors driving Klebsiella liver abscess in an ethnically diverse population

Abstract

Hypervirulent Klebsiella pneumoniae is an emerging cause of community-acquired pyogenic liver abscess. First described in Asia, it is now increasingly recognized in Western countries, commonly afflicting those with Asian descent. This raises the question of genetic predisposition versus geospecific strain acquisition. We leveraged on the Antibiotics for Klebsiella Liver Abscess Syndrome Study (A-KLASS) clinical trial ongoing in ethnically diverse Singapore, to prospectively examine the profiles of 70 patients together with their isolates’ genotypic and phenotypic characteristics. The majority of isolates belonged to capsule type K1, a genetically homogenous group corresponding to sequence-type 23. The remaining K2, K5, K16, K28, K57 and K63 isolates as well as two novel cps isolates were genetically heterogeneous. K1 isolates carried higher frequencies of virulence-associated genes including rmpA (regulator of mucoid phenotype A), kfu (Klebsiella ferric uptake transporter), iuc (aerobactin), iro (salmochelin) and irp (yersiniabactin) than non-K1 isolates. The Chinese in our patient cohort, mostly non-diabetic, had higher prevalence of K1 infection than the predominantly diabetic non-Chinese (Malays, Indian and Caucasian). This differential susceptibility to different capsule types among the various ethnic groups suggests patterns of transmission (e.g. environmental source, familial transmission) and/or genetic predisposition unique to each race despite being in the same geographical location.

Genetic diversity, mobilisation and spread of the yersiniabactin-encoding mobile element ICEKp inKlebsiella pneumoniaepopulations

“…In (13)) obtained from various sources representing a diverse geographical and clonal distribution (Table S1; see Table S4 for full list of isolates and their properties). Just under a third of these genomes had been collected and sequenced in-house from four previous studies of human hospital isolates (13,(42)(43)(44).…”

First report of invasive liver abscess syndrome with endophthalmitis caused by a K2 serotype ST2398 hypervirulent Klebsiella pneumoniae in Germany, 2016

“…When performing a Medline search using the terms ‘hypervirulent,’ ‘ Klebsiella pneumoniae ’ and ‘Germany,’ we found no case of severe infection published using these keywords. Currently investigations to determine a predisposition for infections by hypervirulent strains are ongoing [20].…”

Hypervirulent Klebsiella pneumoniae – clinical and molecular perspectives

“…Presently, sequencing of the capsule synthesis wzi genes has become mainstream, and at least 134 distinct K loci have been identified [77]. The most common capsule locus associated with hvKp is K1, followed by K2, K5 and K57 [42,65,74,[78][79][80][81][82].…”