Evaluation of phenotypic and genotypic methods for detecting KPC variants

Area of Science:

• Microbiology
• Molecular Biology
• Clinical Diagnostics

Background:

• Klebsiella pneumoniae carbapenemases (KPCs) are a growing threat, with 242 identified variants possessing diverse hydrolytic abilities.
• Accurate detection of KPC variants is critical for effective treatment and infection control in healthcare settings.

Purpose of the Study:

• To assess the impact of KPC variant diversity on the detection capabilities of various resistance-based diagnostic methods.
• To evaluate the sensitivity of different KPC detection techniques, including immunoassays, hydrolysis tests, culture media, and PCR.

Main Methods:

• Phenotypic characterization of 45 constructed KPC variants.
• Testing the detection sensitivity of two lateral flow immunoassays (LFIA), three hydrolysis tests, three selective culture media, and two PCR-based tests.
• Analysis of antibiotic susceptibility patterns for KPC variants.

Main Results:

• Four distinct antibiotic susceptibility patterns were identified among KPC variants.
• Detection capabilities varied significantly across methods: PCR detected all variants, LFIA showed high sensitivity (44%-100%), while hydrolysis tests and culture media had lower and variable sensitivity (0%-100%).
• Some KPC variants pose a risk of misdiagnosis due to limitations in current detection methods.

Conclusions:

• PCR-based tests are comprehensive for KPC variant detection.
• Lateral flow immunoassays (LFIA) are recommended as a sensitive first-line screening tool.
• A combination of selective media targeting carbapenems, cephalosporins, and ceftazidime-avibactam is necessary for comprehensive fecal carriage screening.
• Antibiotic susceptibility testing results, particularly resistance to ceftazidime ± avibactam, should serve as an alert for potential KPC variant presence.