Increased Rates of Resistant S pneumoniae Infection Observed Among US Children

Despite vaccine-attributable disease reductions, high rates of antimicrobial-resistant (AMR) Streptococcus pneumoniae isolates were found among children with invasive and noninvasive pneumococcal disease within the past decade. These study results were published in Open Forum Infectious Diseases.

Researchers conducted a retrospective study between January 2011 and February 2020 among US children at 219 inpatient and outpatient facilities. Invasive and noninvasive S pneumonia isolates were obtained and evaluated for AMR. Invasive S pneumoniae isolates were collected from cerebrospinal fluid or blood, and noninvasiveisolates were collected from respiratory samples or the ear, nose, or throat. The researchers used descriptive statistics to assess variations in AMR over time. The primary outcome was the percentage of overall resistance by year, sex, age group, hospital characteristics, and invasive vs noninvasive pneumococcal disease.

There were 7605 S pneumoniae isolates included in the analysis, of which 36.9% were obtained from patients aged 2 to 4 years, 35.1% from those aged 5 to 17 years, and 28.1% from those younger than 2 years. Most isolates (87.3%) were obtained from children with noninvasive pneumococcal disease.

Noninvasive isolates conferred higher rates of AMR when compared with invasive isolates, irrespective of drug class. More than half (56.8%) of the overall isolates were resistant to at least 1 drug class, and 30.7% were resistant to at least 2 drug classes.

Further analysis showed that isolates were most commonly resistant to macrolides (39.9%) and penicillin (39.6%), with 11.0% of isolates resistant to tetracycline. Rates of resistance among noninvasive vs invasive isolates to at least 1 drug class, 2 or more drug classes, macrolides, and penicillin were 59.0% vs 42.2%, 33.0% vs 14.8%, and 41.1% vs 31.7%, respectively.

Multivariable analyses showed the highest levels of AMR among isolates obtained from children younger than 2 years and the lowest levels among isolates obtained from those aged 5 to 17 years. In addition, invasive isolates among children aged to 4 years conferred the highest levels of AMR to at least 1 drug class, 2 or more drug classes, macrolides, and penicillin. Overall, AMR rates were higher among isolates collected via blood vs cerebrospinal fluid or neurologic samples.

Significant increases in the annual rate of S pneumoniae isolates with resistance to at least 1 (0.9% per year) or 2 or more (1.8% per year) drug classes were observed between January 2011 and February 2020 (both P <.001). Similar increases were observed for noninvasive pneumococcal disease isolates, whereas changes in annual resistance rates among invasive isolates were not significant. Among all isolates, resistance to macrolides increased by 5.0% per year (P <.001).

Limitations of this study include the use of reports from inpatient and outpatient facilities to determine AMR rates, changes in resistance breakpoints during the study period, potential selection bias, and the lack of data on S pneumoniae serotypes or pneumococcal vaccination status.

According to the researchers “Addressing the high and increasing rates of S. pneumoniae resistance may require PCVs with expanded serotype coverage and targeted antimicrobial stewardship efforts.”

Disclosure: This research was supported by Merck & Co., Inc. Please see the original reference for a full list of disclosures.