Comparison of Lateral Flow Test and PCR for Carbapenemase Detection in Carbapenem-Resistant Klebsiella pneumoniae and the Ceftazidime-Avibactam Resistance Profile.

BACKGROUND

Carbapenem-resistant Klebsiella pneumoniae (CRKp) strains are a major public health threat.

AIM: This study aimed to compare multiplex lateral flow immunochromatographic testing (LFT) and polymerase chain reaction (PCR) for detecting carbapenemase genes in carbapenem-resistant K. pneumoniae (CRKp). A secondary objective was to assess the gene-specific susceptibility profile of these isolates to critical antimicrobial agents: ceftazidime-avibactam (CZA), last-resort options (colistin, amikacin).

METHODS

CRKp isolates from patient samples (blood, urine, and respiratory tract) were identified based on colony morphology, Gram stain, and the BD Phoenix M50system. Isolates resistant to ≥1 carbapenem per EUCAST criteria were included. Resistant isolates underwent PCR for bla KPC, bla NDM, bla VIM, bla IMP, and bla OXA-48 genes, and carbapenemase production was phenotypically confirmed using a commercial immunochromatographic test (ICT) kit (detecting OXA-48-like, NDM, VIM, IMP, KPC simultaneously). Susceptibility to ceftazidime-avibactam (CAZ-AVI), colistin, and amikacin was assessed according to EUCAST standards. The study was conducted in Western Anatolia, in Balıkesir, Türkiye.

RESULTS

The distribution patterns of the isolates showed that blaOXA-48 predominated (n = 27, 38.0% of positive isolates), followed by blaKPC (n = 15, 21.1%) and blaNDM (n = 7, 9.9%). Notably, 22 isolates (31.0%) harbored multiple carbapenemase genes: OXA-48 + NDM (n = 14, 19.7%), KPC + NDM (n = 4, 5.6%), and OXA-48 + KPC (n = 4, 5.6%). Neither blaVIM nor blaIMP was detected. The lateral flow test (LFT) demonstrated good agreement with PCR for the detection of blaKPC and blaOXA-48 genes (Cohen's κ = 0.72 and 0.65, respectively); however, its accuracy decreased in isolates harboring multiple carbapenemase genes. While susceptibility to ceftazidime- avibactam averaged 28.6% overall among CP-Kp isolates, it varied according to carbapenemase type, with KPC producers exhibiting the highest rate (46.7%).

CONCLUSIONS

These findings highlight the importance of rapid and easily applicable diagnostic tests, as well as the urgent need for new antimicrobial agents and novel therapeutic approaches (e.g, Phage therapy, immunotherapies).