Investigation of the susceptibility rates to ceftazidime-avibactam and colistin, clonal relationships, and clinical data of patients with carbapenem-resistant Klebsiella pneumoniae isolates detected in the ICUs of a hospital in İstanbul.

BACKGROUND

The increase in carbapenem-resistant K. pneumoniae (CR-Kp) in intensive care units (ICUs) causes treatment difficulties and increases risk in mortality.

OBJECTIVES

The aim of this study was to investigate the susceptibility rates of CR-Kp isolates obtained from ICUs to ceftazidime-avibactam (CAZ-AVI) and colistin, carbapenem resistance genes, clonal relationships and clinical characteristics of the patients.

DESIGN

Retrospective cohort.

SETTING

Single-center, University of Health Sciences, Ümraniye Training and Research Hospital.

MATERIALS AND

METHODS

This study was conducted between June 2023 and December 2024. Isolates were identified using VITEK MS v.3.2, and antibiotic susceptibility testing was performed using the VITEK 2 Compact system. CAZ-AVI susceptibility was determined using disk diffusion, and colistin susceptibility was determined using broth microdilution to determine minimum inhibitory concentration (MIC) values. Carbapenem resistance genes were determined using multiplex real-time polymerase chain reaction (RT-PCR) and clonal relationship arbitrarily primed-polymerase chain reaction (AP-PCR).

MAIN OUTCOME MEASURES: Resistance genes of CR-Kp isolates, clonal relationships, CAZ-AVI and colistin resistance, and clinical characteristics of patients.

SAMPLE SIZE: Ninety-seven isolates from 76 patients.

RESULTS

Among patients with CR-Kp isolates, central venous catheter use was detected in 59 cases (78%), ventilator-associated pneumonia in 44 cases (58%), and bacteremia in 39 cases (51%), respectively. It was determined that 53 of the patients (70%) died. Using the AP-PCR method, 60 different genotypes were identified among 97 isolates, and clustering was determined in 42 of the isolates (46%). It was determined that 36 (37%) of the isolates were resistant to colistin and 42 (45%) were resistant to CAZ-AVI. NDM+OXA-48, OXA-48, KPC, KPC+NDM, and NDM genes were detected in 40 (43%), 32 (35%), 10 (11%), 2 (2%), and 3 (3%) isolates, respectively. It was determined that 30 (75%) of the isolates with NDM+OXA-48 and only 4 (12%) of the isolates with OXA-48 were resistant to CAZ-AVI.

CONCLUSION

In addition to OXA-48, an increase in the frequency of CR-Kp isolates containing the NDM, NDM+OXA-48, KPC+NDM, and OXA-48+KPC genes were also detected. It was also determined that resistance to colistin and CAZ-AVI is increasing. The AP-PCR method can also be used to investigate infections.

LIMITATIONS: Single center, Pulsed Field Gel Electrophoresis (PFGE) could not be performed together with AP-PCR.