Carbapenem-Resistant Klebsiella pneumoniae Clinical Isolates: In Vivo Virulence Assessment in Galleria mellonella and Potential Therapeutics by Polycationic Oligoethyleneimine.

Dalila Mil-Homens,Rita F Pires,Sandra N Pinto,Maria Martins,Maria J Sarmento,Vasco D.B Bonifácio,José Barbosa,Gabriel Serafim,Vitória Rodrigues

doi:10.3390/antibiotics10010056

Abstract

Klebsiella pneumoniae, one of the most common pathogens found in hospital-acquired infections, is often resistant to multiple antibiotics. In fact, multidrug-resistant (MDR) K. pneumoniae producing KPC or OXA-48-like carbapenemases are recognized as a serious global health threat. In this sense, we evaluated the virulence of K. pneumoniae KPC(+) or OXA-48(+) aiming at potential antimicrobial therapeutics. K. pneumoniae carbapenemase (KPC) and the expanded-spectrum oxacillinase OXA-48 isolates were obtained from patients treated in medical care units in Lisbon, Portugal. The virulence potential of the K. pneumonia clinical isolates was tested using the Galleria mellonella model. For that, G. mellonella larvae were inoculated using patients KPC(+) and OXA-48(+) isolates. Using this in vivo model, the KPC(+) K. pneumoniae isolates showed to be, on average, more virulent than OXA-48(+). Virulence was found attenuated when a low bacterial inoculum (one magnitude lower) was tested. In addition, we also report the use of a synthetic polycationic oligomer (L-OEI-h) as a potential antimicrobial agent to fight infectious diseases caused by MDR bacteria. L-OEI-h has a broad-spectrum antibacterial activity and exerts a significantly bactericidal activity within the first 5-30 min treatment, causing lysis of the cytoplasmic membrane. Importantly, the polycationic oligomer showed low toxicity against in vitro models and no visible cytotoxicity (measured by survival and health index) was noted on the in vivo model (G. mellonella), thus L-OEI-h is foreseen as a promising polymer therapeutic for the treatment of MDR K. pneumoniae infections.

Highlights

In the light of this, in this study, we report the use of a polycationic synthetic oligomer, linear oligoethyleneimine hydrochloride (L-OEI-h), as an antimicrobial agent for the treatment of K. pneumonia K. pneumoniae carbapenemase (KPC)(+) and OXA48(+) bacterial infections
Ten K. pneumoniae isolates (Table S1) with reduced sensitivity to carbapenems were obtained from different clinical specimens
We previously demonstrated that L-OEI-h is able to target some Gram-positive bacteria with low efficiency [19], as demonstrated here for methicillin-resistant S. aureus

Summary

Introduction

The widespread use of antibiotics in clinics caused an increased frequency of multidrugresistance bacteria mainly due to bacterial mutations [1]. The emergence of resistance to last resource antibiotic treatment options (including carbapenems) has contributed to the limitation of effective therapeutics. From all the compounds under development, very few target infections were caused by Gram-negative bacteria [2,3,4]. Gram-negative bacteria infections are significantly more lethal compared to those caused by the Gram-positive [3]. Several factors contribute to the scarcity of new antibiotics, market

Methods

Results

Conclusion