Acinetobacter baumannii has emerged in the last decades as one of the most concerning opportunistic pathogen responsible for infections in health care settings, due to the paucity of antibiotics still effective against this microorganism. Moreover, these infections can become life threating for patients attending respiratory rehabilitation, exacerbating the underlying disease. The most effective antibiotics used against A. baumannii were carbapenems (Cb). However, the incidence of Cb-resistant isolates has raised significantly. The Cb-resistance is mainly due to production of various carbapenemases, several efflux pump systems and porin modifications or loss. Up to now, few studies addressed the simultaneously expression of these resistance mechanisms under antibiotic exposure. Therefore, the aim is to measure and comparing the expression of the genes that contribute the most to antibiotic resistance in selected A. baumannii isolates Cb-resistant, by Real Time-PCR. The reference strain AB5075 and in a set of clinical isolates collected from patients admitted to the Rehabilitation Respiratory Unit of IRCCS San Raffaele, Pisana suffering from different pulmonary diseases (e.g. chronic obstructive pulmonary disease, pulmonary fibrosis, emphysema, chronic respiratory insufficiency, lung transplant, bronchiectasis, major thoracic surgery) will be analyzed. The clinical impact of infections caused by Cb-resistant A. baumannii isolates on patients¿ conditions will also be evaluated. These studies could enhance our knowledge on key players in Cb-resistance providing a foundation for new therapeutic strategies to combat A. baumannii infections as well as identifying potential risk factors in susceptible patients that will allow to adopt appropriate preventive measures against these community-associated infections.
The increasing rates of bacterial resistance among A. baumannii are threatening the effectiveness of antibiotics used as last-resort therapeutic options. Moreover, A. baumannii has established a niche in healthcare environments, including hospitals and communities. Cb have long been regarded as the agents of choice, but resistance rates A. baumannii Cb-resistant have risen substantially, especially in Italy (ECDC, 2018; Nowak et al., 2017). Regretfully, also the old off-patent drug colistin used to treat these life-threating infections is becoming ineffective due to the increase of isolates colistin-resistant (Nowak et al., 2017). Therefore, new insights in the mechanisms that A. baumannii adopts to resist to Cb can increase our knowledge on the strategies of this life-threatening opportunistic pathogen. In addition, gathering epidemiological data and risk factors of patients attending Respiratory Rehabilitation Units will help to develop specific measures to combat these infections, contributing to a better patients¿ clinical status and outcome.
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