Impact of Siderophore Genes on Cefiderocol Susceptibility in Carbapenem Resistant Hypervirulent Klebsiella Pneumoniae

Klebsiella pneumoniae ( K.pneumoniae ) is a Gram-negative, encapsulated, non-motile bacterium of the Enterobacteriaceae family and a major pathogen responsible for a broad spectrum of healthcare- and community-acquired infections, including pneumonia, urinary tract infections, bloodstream infections, and pyogenic liver abscesses

1. Sample: Clinical specimens (blood, urine, sputum, wound swabs) will be collected aseptically and transported to the microbiology laboratory for analysis.
2. Culture: Specimens will be inoculated on MacConkey agar and incubated at 35-37°C for 18-24 hours. Colonies with typical K. pneumoniae morphology (mucoid, lactose-fermenting) will be selected for further testing
3. Identification of isolates will be done by:

Colony morphology, Gram staining, and conventional biochemical tests (eg, indole, citrate utilization, urease, Voges-Proskauer) . 4. Antimicrobial susceptibility testing of the isolates :

Antimicrobial susceptibility testing was performed and interpreted according to the Clinical and Laboratory Standards Institute (CLSI) guidelines, M100 document (latest edition)." 5. MIC determination for cifederecol using E-test . 6. Phenotypic Detection of hvKP:

1. String Test: A viscous string ≥5 mm formed by stretching a single colony indicates hypermucoviscosity .
2. Capsule Staining: to visualize large capsules .
3. Siderophore Production: Assessed on chrome azurol S (CAS) agar to detect iron-chelating activity.
4. Detection of siderophore genes by Simple qualitative PCR .