Clinical characteristics and molecular epidemiology associated with imipenem-resistant Klebsiella pneumoniae

Area of Science:

• Infectious Diseases
• Microbiology
• Clinical Medicine

Background:

• Imipenem is a critical antibiotic for treating multidrug-resistant Gram-negative infections.
• Klebsiella pneumoniae is a common cause of hospital-acquired infections, particularly in intensive care units.
• Previous resistance to other antibiotics often precedes imipenem resistance development.

Purpose of the Study:

• To investigate the emergence of imipenem resistance in Klebsiella pneumoniae during imipenem therapy.
• To identify clonal patterns and mechanisms of resistance development.
• To understand the clinical implications of imipenem use in patients with pre-existing resistance.

Main Methods:

• Retrospective analysis of eight patients with imipenem-resistant Klebsiella pneumoniae (IRKP) infections or colonization.
• Characterization of initial and sequential Klebsiella isolates for antibiotic susceptibility.
• Pulsed-field gel electrophoresis (PFGE) to determine clonal relatedness of isolates.

Main Results:

• Eight patients in a surgical intensive care unit developed IRKP during imipenem treatment.
• Initial isolates were susceptible to imipenem but resistant to cephalosporins, aminoglycosides, and beta-lactam inhibitor combinations.
• PFGE revealed three distinct clonal patterns, with two patients showing identical patterns in sequential susceptible and resistant isolates, suggesting stepwise resistance.
• IRKP was recovered during or after imipenem therapy in all patients.

Conclusions:

• Imipenem resistance in Klebsiella pneumoniae can develop during imipenem therapy, particularly in patients with strains already resistant to other antibiotics.
• Clonal stepwise resistance suggests that imipenem treatment can select for and promote the emergence of resistance.
• This highlights the importance of judicious imipenem use and surveillance for resistance in high-risk patient populations.