Volume 60 (2021): Issue 4 (December 2021)

The growing problem of antimicrobial resistance has been classified by the World Health Organization (WHO) as one of the top ten threats to mankind. In a special report published in 2017, the WHO presented a list of microorganisms for which the search for new therapeutic options is a priority. The highest (critical) priority was given to the search for new antibiotics active against carbapenem-resistant strains of Acinetobacter baumannii and Pseudomonas aeruginosa as well as against carbapenem- and third-generation-cephalosporin-resistant Enterobacterales strains (so-called critical priority pathogens). Whereas the second (high) priority was given among others to the search for new antibiotics active against methicillin- and vancomycin-resistant strains of Staphylococcus aureus (MRSA and VRSA) and vancomycin-resistant strains of Enterococcus faecium (VRE). Since the publication of the WHO report the European Medicines Agency has approved 6 novel, broad-spectrum antibiotics, from 6 different groups, addressing the priority pathogens to a different extent. Two of them are new combinations of carbapenems with non-β-lactam inhibitors of β-lactamases (active also against carbapenemases), belonging to two novel groups of inhibitors: diazabicyclooctanes (relebactam, combined with imipenem) and boronates (vaborbactam, combined with meropenem). The third new drug is a siderophore cephalosporin (cefiderocol) with an innovative mechanism of penetration into the bacterial cell. The next two antibiotics are the new fluoroquinolone (delafloxacin) and the new tetracycline (eravacycline), designed and synthesized to be more active than older members of these groups. The last innovative antibiotic is lefamulin – the first pleuromutilin approved for systemic use in humans. New approvals have expanded the number of available therapeutic options in the treatment of complicated urinary tract infections (meropenem/vaborbactam, cefiderocol), complicated intra-abdominal infections (meropenem/vaborbactam, eravacycline), nosocomial pneumonia (meropenem/vaborbactam, imipenem/relebactam), acute bacterial skin and skin structure infections (delafloxacin) and community-acquired pneumonia (lefamulin).

Acinetobacter baumannii is a Gram-negative saprophytic rod inhabiting both moist niches and dry surfaces. The wide spread of the microbe in the environment by means of minimal nutritional requirements and exceptional survival capabilities give the opportunities to occupy hospital niches, and thus to create threats for hospitalized patients. This bacterium may be a part of the human microbiota as an opportunistic pathogen which upon the host’s weakening, causes less or more serious diseases. A. baumannii is an etiological factor of ventilator-associated pneumonia, which is especially dangerous for patients in intensive care units (in Poland every fifth patient suffers from such infection). Due to the increasing multidrug resistance of A. baumannii, this bacterium belongs to the group of priority pathogens. Fighting such dangerous bacteria is difficult due to their natural resistance as well as acquired resistance mechanisms in response to environmental threats. The unique ability of A. baumannii to cause diseases and acquire resistance to numerous antibiotics, make it necessary to control and prevent these infections.