Multidrug-resistant gram-negative infections. Bringing back the old.

Multidrug-resistant (MDR) gram-negative infections have become challenging to treat when there is only a limited armamentarium of anti-infectives that are commercially available. In particular, increasing resistance of gram-negative organisms such as Klebsiella pneumoniae, Acinetobacter baumanii, Pseudomonas aeruginosa, and Enterobacter species have become concerning. Carbapenems have been used to treat extended-spectrum-β-lactamase (ESBL)-producing Escherichia coli and Klebsiella species infections. However, because of carbapenemase-producing K pneumoniae strains, other MDR gram-negative infection treatment options are limited to antibiotics with in vitro spectrum of activity against these MDR pathogens and may include the use of tigecycline, polymyxin B, or polymxyin E (colistin). Because of the potential for nephrotoxicity or neurotoxicity with the polymyxins, clinicians should be vigilant in preventing its adverse effects. Clinicians are encouraged to support the Infectious Diseases Society of America's 10 × '20 Initiative in gaining global commitment to develop additional antimicrobials for the future.