Streptococcus pneumoniae Isolates Are 99.99% Susceptible to Antibiotics

A review of US hospital data showed that Streptococcus pneumoniae isolates were 99.99% susceptible to antibiotics between 2010 and 2020, according to new research presented at CHEST 2021. All extensively drug-resistant isolates were susceptible to ceftaroline, linezolid, and vancomycin.

To evaluate trends in the susceptibility of Streptococcus pneumoniae to antimicrobial agents, the researchers collected nearly 8000 isolates from 28 US medical centers from 2011 to 2020 and tested them for susceptibility to ceftaroline, a broad-spectrum cephalosporin active against S pneumoniae, and to comparator agents. Ceftaroline is approved for treating community-acquired bacterial pneumonia in the United States.  Susceptibility testing was conducted via Clinical and Laboratory Standards Institute broth microdilution methods, and selected isolates were serotyped.

During the study period, ceftaroline showed potent and consistent activity against S pneumoniae, including several resistant phenotypes and less-susceptible serotypes.  Susceptibility to ceftaroline was 99.99%, and susceptibility to levofloxacin ranged from 98.9 to 100%. In contrast, susceptibility to erythromycin decreased from 56.4% in 2011 to 52.2% in 2014.

Multidrug resistance rates ranged from 23.7% in 2011 to 16.2% in 2020, and rates of extensive drug resistance ranged from 13.3% in 2011 to 1.8% in 2019. However, all extensively drug-resistant isolates were susceptible to ceftaroline, linezolid, and vancomycin, and 97.5% were susceptible to tigecycline.

“[S pneumoniae] susceptibility to many antibiotics increased from 2011 to 2015 but remained stable in 2016-2020. Increases in susceptibility rates could be related to the [13-valent, conjugate] anti-pneumococcal vaccine introduced in 2010. Continued surveillance is crucial since resistance clones not covered by the vaccine may expand,” the researchers noted.

—Ellen Kurek

Reference:

Sader H, Carvalhaes C, Streit S, Shortridge D, Mendes R, Castanheira M. Evaluation of the in vitro activity of ceftaroline and comparators against Streptococcus pneumoniae isolates from the United States: results from 10 years of the AWARE Surveillance Program (2010–2020). Paper presented at: CHEST 2021 Annual Meeting; October 17-20, 2021; Virtual