Does Prolonged IV Amikacin Therapy Improve Outcomes in M Abscessus?

Prolonged intravenous (IV) administration of the drug amikacin fails to provide better treatment results in patients with Mycobacterium abscessus pulmonary disease (PD), according to findings of a recent retrospective review published in the Journal of Infection and Chemotherapy.

Although a multidrug treatment program including amikacin has been recommended for the difficult to treat M. abscessus PD, only 30% to 40% of patients see beneficial results. Authors of the current review sought to determine whether longer administration of the prescribed regimen had produced microbiological cure.

Researchers based in Seoul, South Korea pulled data from the medical records of 62 patients hospitalized at 3 tertiary medical centers between January 2006 and December 2019 who received IV amikacin for at least 4 weeks and IV beta-lactams for at least 2 weeks.

The hospitalized patients received the drug regimen containing amikacin on various schedules ranging from daily (27/62, 43.5%), to 5 times per week (28/62, 45.2%), to 3 times per week (7/62, 11.3%). Many patients continued to get the drug regimen after discharge, most frequently 3 times per week (25/62, 40.3%).

The median duration of therapy for amikacin was 25.1 weeks, whereas for beta-lactams, the duration was 8.2 weeks.

Despite the longer treatment, the overall cure rate was only 29.0% among the 62 patients evaluated. Culture positivity remained in 44 patients 8 weeks after treatment with the regimen containing amikacin. Of the 44 patients, 30 were female, and the mean age was 58.2±12.3 years.

The median parenteral amikacin treatment duration after 8 weeks was 18.0 weeks, and the conditional probability of microbiological cure was 18.2% (95% CI, 8.2-32.7). Conditional probability fell to 8.8% (95% CI, 1.9-23.7) in 34 patients who did not reach cultural conversion at 12 weeks, dropped even more after 16 weeks, and reached 0% at 28 weeks after the beginning of treatment.

“These findings suggest that the continuation of intravenous amikacin therapy was usually not followed by culture conversion in patients who showed persistent culture positivity over several months after treatment initiation,” the authors noted. They added that treatment guidelines on M. abscessus PD from varying organizations offer conflicting recommendations on treatment duration because no previous research has evaluated the effects of treatment duration on outcomes.

“The poor therapeutic outcome even with the long-term course of amikacin could be explained by the lack of bactericidal activity of amikacin against M. abscessus,” the authors contended. “These findings suggest that maintenance of extended parenteral amikacin therapy would not be helpful in improving microbiological outcomes in most patients with M. abscessus PD who did not achieve culture conversion within several months,” they concluded.

Reference

Park YE, Park SY, Jhun BW, et al. Treatment outcome of continuation of intravenous amikacin for Mycobacterium abscessus pulmonary disease with a persistent culture positivity after the treatment initiation. J Infect Chemother. Published online April 20, 2022. doi:10.1016/j.jiac.2022.03.026