Antimicrobial resistance pattern and molecular characterization of hypervirulent Klebsiella pneumoniae among hospital-acquired infections in the intensive care unit

Background : A variant of Klebsiella pneumoniae has emerged more than twenty years ago, and was named “hypervirulent” K. pneumoniae (hvKp). This variant can be differentiated from the “classic” K. pneumoniae (cKp) by its hypermucoviscosity and being incriminated in invasive infections affecting healthy individuals as well as those with immune suppression. Aim: This study aimed to detect the frequency of hvKp in intensive care units among hospital acquired K. pneumoniae infections, and to analyze the differences in antimicrobial resistance patterns and molecular characteristics between hvKp and cKp. Methods : A total of 127 K. pneumoniae isolates were recovered from different hospital acquired infections. These isolates were subjected to string test for detection of hypermucovuscosity, antimicrobial susceptibility testing, biofilm formation, and detection of virulence-associated genes (iucA, rmpA, rmpA2, magA) using polymerase chain reaction (PCR). Results: Out of 127 K. pneumoniae isolates, 57 (44.9%) isolates showed the hypermucoviscous phenotype and 41.7% were hvKp. The rmpA, rmpA2 and magA genes were significantly associated with hvKp. All K. pneumoniae isolates were multi-drug resistant (MDR) exhibited high resistance rates for most of the tested antibiotics. Biofilm production was detected in 46/53 (86.8%) of hvKp and in 48 out of 74 (64.9%) cKp isolates. Conclusion: HvKp was frequently isolated from hospital acquired infection specifically ICU patients with a warning rate of antimicrobial resistance and high rate of biofilm formation. String test remains an easy and simple phenotypic test however, genotypic detection of hvKp virulence genes remains the gold standard confirmatory tool for identification of these strains.