US doctors neglected new antibiotics in treating resistant infections

American scientists conducted a retrospective cohort study and concluded that despite the availability of recently approved new generation antibiotics, doctors prefer to treat drug-resistant Gram-negative infections with older drugs in almost half of cases. A publication about this appeared in the journal Annals of Internal Medicine. Jeffrey Strich and colleagues at the US National Institutes of Health, as part of the NIH-ARORI Resistant Infections Research Initiative, analysed trends in the use of seven new antibiotics in 619 US hospitals from the first quarter of 2016 to the second quarter of 2021. These drugs included ceftazidime/avibactam, ceftolozane/tazobactam, meropenem/vaborbactam, plazomicin, eravacycline, imipenem/relebactam/cilastatin, and cefiderocol.

Among more than 362,000 hospital admissions for gram-negative infections, 0.7 percent (2,631 cases) were caused by difficult-to-treat resistant pathogens (i.e., resistant to all first-line antibiotics). In 41.5 per cent (1,091) of cases, patients were treated with conventional drugs with suboptimal efficacy and safety profiles, with 79.3 per cent (865) of patients receiving reserve antibiotics such as polymyxins, some aminoglycosides or tigecycline. Among the newer drugs, physicians favoured ceftolozane/tazobactam (approved in the US in 2014) ceftazidime/avibactam (in 2015). The others were rarely used, and plazomicin was not used at all (its manufacturer filed for bankruptcy). The likelihood of using new antibiotics increased when sensitivity tests were conducted. According to the authors of the paper, such an unsuccessful introduction of new drugs threatens their further development and is fraught with accelerated growth of antibiotic resistance in Gram-negative bacteria.