Abstract

Pseudomonas aeruginosa is one of the most important opportunistic pathogens worldwide, since it presents one of the highest morbidity and mortality rates, mainly due to its high antibiotics resistance and virulence. Although, a few years ago, Chilean hospitals presented a higher incidence of other bacterial pathogens different to P. aeruginosa, the current situation is changing and different types of P. aeruginosa infections associated with health care are worryingly increasing. Taking into account that carbapenem-resistant P. aeruginosa is one of the priority pathogens established by WHO for searching and discovering new antimicrobials, it is important to know how the increased clinical incidence of P. aeruginosa infections observed in Chile could be affecting the carbapenem resistance level of this pathogen. Different works have evidenced that, in recent years, P. aeruginosa clinical isolates are showing a very significant increase in carbepenems resistance, which also leads to an increase in both multi-drug resistance and the acquisition of carbapnemases by horizontal gene transfer (HGT). Furthermore, an increase in carbapenemases diversity has been observed in clinical isolates of P. aeruginosa and other healthcare-associated pathogens, which is even more worrying considering that, in some cases, these enzymes were associated to clonal populations that could be favoring their prevalence and dispersion. However, the presence of these enzymes is not the most frequent carbapenem resistance mechanism in P. aeruginosa, becoming evident that studies focused on non-carbapenemase producer clinical isolates should be carried out. In this sense, we wanted to analyze the activity of Ceftolozane|Tazobactam (C|T), a new combined antipseudomonal antibiotic, against carbapenem-resistant, non-carbapenemase producer, P. aeruginosa strains isolated from Chilean hospitals. The results showed a really good activity of C|T against this type of isolates, but also evidenced a decreased activity when isolates presented resistance to several families of β-lactams. Therefore, this antibiotic represents a good alternative for treatment of this type of infection, but its use has to be carefully applied for treatment of those caused by Pan-β-lactam-resistant isolates. All this highlights the current critical situation in Chile regarding P. aeruginosa infections, a situation which could be further worrying in a pandemic world. Agencia Nacional de Investigación y Desarrollo a través del programa FONDECYT de postdoctorado (FONDECYT Nº 3200798) y de la iniciativa Milenio (MICROB-R, Ref: NCN17-08).