Assessment of the last-resort antibiotics against Extended Spectrum Beta-Lactamase/carbapenemase and biofilm producer Klebsiella pneumoniae isolated from hospitalized patients in intensive care units (ICUs), Iran

Abstract

Pneumonia caused by Klebsiella pneumoniae (K. pneumoniae) is considered one of the most common causes of hospital-acquired infections. We aimed to investigate the activity of tigecycline, azithromycin, and colistin against K. pneumoniae isolated from bronchoalveolar lavage (BAL) samples of suspected cases of ventilator-associated pneumonia (VAP) in COVID-19 patients. In the current study phenotypic and genotypic screening of ESBLs, AmpC beta-lactamases, and carbapenemase enzymes was investigated. the activity of tigecycline, azithromycin, and colistin against ESBL/carbapenemase producer K. pneumoniae. Also, assessment of the ability of biofilm formation was performed. Finally, virulence genes were detected by the PCR method. By phenotypic detection tests 27 (29.6%) out of 91 K. pneumoniae isolates were classified as ESBL/carbapenemase-producing K. pneumoniae strains. Also, molecular methods showed, all 27 K. pneumoniae isolates harbored at least 1 of the ESBL/carbapenemase-related genes. ESBL-associated genes (19.7% blaTEM, 29.6% blaSHV, and 19.7% blaCTX-M) were detected in 91 K. pneumoniae isolates. Carbapenemase-related genes were detected in 17.5% of these isolates (blaOXA-48-like 15.4%, and blaNDM1 2.1%). All of the 27 selected isolates, exhibited biofilm formation ability. In this study, 92.59%, 92.59%, 81.48%, 88.8%, 40.74%, 11.1 %, 22.22%, 18.5%, 14.81% and 33.33% of the ESBL/carbapenemase producer K. pneumoniae isolates carried entB, mrkD, fimH, Irp2, wcaG, mrkA, rmpA, iutA and magA genes, respectively. But iucA gene was not present in any of isolates. Tigecycline and colistin were more effective against these isolates. Multilocus sequence typing (MLST) results for four colistin-resistant isolates showed three different sequence types ‌‌ST: ST3500, ST273, and 2 cases of ST2558. The rapid emergence and spread of colistin-resistant and Beta-lactamase producer K. pneumoniae has resulted in an alarming situation worldwide. The effective antimicrobial activity of tigecycline against K. pneumoniae that produce these enzymes may be efficient in hospitalized patients in ICUs with suspected cases of VAP.