K. pneumoniae Carbapenemase

K. pneumoniae Carbapenemase Full Name

Klebsiella pneumoniae Carbapenemase

K. pneumoniae Carbapenemase Introduction

Klebsiella pneumoniae carbapenemase (KPC) is a class A serine beta-lactamase that confers resistance to carbapenems and virtually all other beta-lactam antibiotics, representing one of the most clinically significant antimicrobial resistance mechanisms threatening global public health. First identified in a K. pneumoniae isolate from North Carolina in 1996 (KPC-1, later shown to be identical to KPC-2), KPC-producing organisms have subsequently disseminated worldwide, causing healthcare-associated outbreaks with high morbidity and mortality. The blaKPC gene is typically carried on the Tn4401 transposon, which is itself located on various conjugative plasmids, facilitating horizontal transfer among Enterobacteriaceae and contributing to the rapid spread of carbapenem resistance. Multiple KPC variants (KPC-2 through KPC-24 and beyond) have been identified, differing by single amino acid substitutions that may affect enzyme activity, substrate specificity, or susceptibility to beta-lactamase inhibitors. KPC enzymes efficiently hydrolyze penicillins, cephalosporins, aztreonam, and carbapenems, and are only weakly inhibited by classical beta-lactamase inhibitors (clavulanate, sulbactam, tazobactam), although newer inhibitors (avibactam, vaborbactam, relebactam) demonstrate potent KPC inhibition.

The clinical impact of KPC-producing K. pneumoniae (KPC-Kp) infections is substantial, with mortality rates ranging from 30-70% in bacteremic patients depending on underlying conditions, infection site, and adequacy of antimicrobial therapy. Risk factors for KPC-Kp infection include prolonged hospitalization, intensive care unit admission, mechanical ventilation, prior antibiotic exposure (particularly carbapenems and fluoroquinolones), presence of invasive devices, and immunocompromising conditions. KPC-Kp infections most commonly manifest as pneumonia (particularly ventilator-associated), bloodstream infections, urinary tract infections, and intra-abdominal infections, with high rates of treatment failure and mortality compared to infections caused by carbapenem-susceptible strains. The limited treatment options for KPC-Kp infections have necessitated the use of "last-resort" antibiotics including polymyxins (colistin, polymyxin B), tigecycline, aminoglycosides (gentamicin, amikacin), and fosfomycin, often in combination regimens to enhance efficacy and prevent emergence of resistance. However, resistance to these agents has emerged, and nephrotoxicity and other adverse effects limit their use.

The development of novel beta-lactam/beta-lactamase inhibitor combinations active against KPC has expanded therapeutic options for KPC-Kp infections. Ceftazidime-avibactam combines a third-generation cephalosporin with avibactam, a diazabicyclooctane inhibitor that potently inhibits KPC and other class A and class C beta-lactamases. Meropenem-vaborbactam pairs a carbapenem with vaborbactam, a cyclic boronic acid inhibitor with potent KPC inhibition. Imipenem-cilastatin-relebactam combines a carbapenem with relebactam, another diazabicyclooctane inhibitor. Clinical trials and real-world experience have demonstrated the efficacy of these agents for treating KPC-Kp infections, with improved outcomes compared to older regimens. However, resistance to ceftazidime-avibactam has already emerged through mutations in blaKPC (e.g., KPC-3 variants with D179Y substitution) or acquisition of metallo-beta-lactamases, underscoring the ongoing challenge of antimicrobial resistance. Surveillance programs, rapid diagnostic methods (including molecular assays and phenotypic tests), infection prevention and control measures, and antimicrobial stewardship are essential components of strategies to contain the spread of KPC-producing organisms and preserve the utility of available therapeutic agents.

Alternate Names for K. pneumoniae Carbapenemase

Klebsiella pneumoniae Carbapenemase; K. pneumoniae Carbapenemase; KPC; Klebsiella pneumoniae; K. pneumoniae; Carbapenemase

• Bacterial Respiratory Infections Catalogue