Detection of DHA-1-Producing Strains and other Associated Virulence Factors of Isolates of Klebsiella pneumoniae from a Nigerian Teaching Hospital

Abstract

Klebsiella pneumoniae strains are a major source of horizontal spread of antimicrobial resistance (AMR) using a plasmid coded 
AmpC β-lactamase Docosahexaenoic acid (DHA-1). DHA-1-producing K. pneumoniae were reported in cases of bacteremia 
from many centers but yet to be reported from our center. We explored the antimicrobial susceptibility profile, significant 
virulence factors and phenotypic detection of DHA-1-producing strains among Klebsiella pneumoniae from Ibadan. Fifty-one 
non-repetitive isolates identified as Klebsiella pneumonia by Vitek 2 were analysed for antimicrobial susceptibility by disc 
diffusion on Mueller Hinton agar. The inducibility of the β-lactamases was detected by the blunting of the oxyimino β-lactam 
zone of inhibition surrounding cefoxitin disc. Klebsiella pneumonia ATCC 700603 control strain was included. Twenty-nine 
(56.9%) was confirmed as ESBL, while 98% (50/51) were resistant to the β-lactam inhibitor (Clavulanic acid), with 88% (44/50) 
showing high-level resistance while 31% (16/51) showed high-level resistance to Cefoxitin. Multiple Antibiotic Resistance index 
ranged from 0.18 – 1.00, with 21 (41.2%) being extensive drug resistant (XDR) and 11 (21.6%) are pan-drug resistant (PDR). 
Twenty (39.2%) and 16 (31.4%) were associated with bacteremia and UTI respectively. All were resistant to killing by human 
serum and 15.7% (8/51) were hypermucoviscous. Ten (19.6%) and 5.9% (3/51) from blood and urine respectively produced 
biofilms. Two (3.9%) demonstrated inducible AmpC β-lactamase. The observed antibiotic susceptibility profiles and presence 
of isolates with DHA-1, poses a threat to successful antibiotic treatments of infections, with transfer of inducible beta-lactam 
resistance among strains of K. pneumoniae and possible dissemination within the hospital and its environment.