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

• Sample: Clinical specimens (blood, urine, sputum, wound swabs) will be collected aseptically and transported to the microbiology laboratory for analysis.
• 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
• Identification of isolates will be done by:

Colony morphology, Gram staining, and conventional biochemical tests (eg, indole, citrate utilization, urease, Voges-Proskauer) .

• 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)."

• MIC determination for cifederecol using E-test .
• Phenotypic Detection of hvKP:

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

Inclusion criteria

• 1. Patients with hypervirulant K. pneumoniae infection from various clinical specimens (blood, urine, sputum, wound swabs, etc.) Confirmed by culture and initial laboratory testing .

• Age and sex range: any age and any sex.

Exclusion criteria

• Patients who received antibiotic treatment in the 48 hours prior to sample collection.

• Patients with incomplete clinical data or inadequate samples.