Rates of Early-Onset Group B Strep Down Among U.S. Infants

Disease caused by early onset group B Streptococcus (GBS) has declined among infants, and rates of late-onset GBS disease are now higher than early onset disease among U.S. infants, researchers found.

From 2006 to 2015, there was a substantial decline in early-onset disease incidence, while late-onset disease incidence remained relatively stable, reported Srinivas Acharya Nanduri, MBBS, MD, MPH, of the CDC in Atlanta, and colleagues.

But a little over 20% of infants with early-onset disease failed to receive intrapartum antibiotic prophylaxis despite having indications for it, pointing to potential gaps in treatment, the authors wrote in JAMA Pediatrics.

Group B streptococcal disease is “a leading infectious cause of morbidity and mortality among infants in the United States,” the authors wrote, and suggested that early onset disease cases “may be preventable” by improved implementation of intrapartum antibiotic prophylaxis guidelines. But they added that late onset disease (defined as 7 to 89 days) is not prevented by intrapartum antibiotics.

Due to concerns about the emergence of antibiotic resistance, maternal immunization is one potential strategy to combat both early and late onset GBS disease, the authors said, citing vaccines under development in phase I and phase II trials.

Active Bacterial Core Surveillance performs population and laboratory-based surveillance for invasive GBS disease in selected counties of 10 U.S. states, they stated.

Overall, there were 1,277 cases of early-onset GBS disease and 1,387 cases of late-onset disease from 2006 to 2015 across surveillance areas. Nearly all cases of early-onset disease occurred within 48 hours of birth, and a little over a quarter were in preterm infants. Median patient age for a positive culture for late-onset disease was 34 days, the authors said. In 2015, the authors estimated 850 cases of early-onset disease and 1,250 cases of late-onset disease.

Incidence of early-onset disease declined during the study period from 0.37 to 0.23 per 1,000 live births (P<0.001), with a case-fatality rate of 6.9% in full-term infants. Annual rates of early-onset disease higher in preterm infants compared with full-term infants and black infants compared with white infants. Researchers also noted a statistically significant decline in early-onset disease among white infants and black infants during this time period.

A little under half of mothers of infants with early-onset disease had no indication for intrapartum antibiotic prophylaxis, and thus did not receive it, while 21.8% did not receive intrapartum antibiotics despite an indication of need, the authors said.

Sagori Mukhopadhyay, MD, and Karen M. Puopolo, MD, both of Children’s Hospital of Philadelphia, characterized this as “frustrating” in an accompanying editorial, specifically citing the 48% of cases of early-onset GBS disease occurring in infants born to women who “did not meet the criteria for [intrapartum antibiotic prophylaxis] either because of a negative GBS screening result or an unknown GBS status without clinical risk factors.”

“Improvements in obstetric practice, aided by electronic health records and decision support tools, may improve the timing and antibiotic choice for [intrapartum antibiotic prophylaxis],” Mukhopadhyay and Puopolo wrote. “Rescreening women with negative antenatal GBS testing results on presentation for delivery with polymerase chain reaction-based point-of-care tests could improve the identification of colonized women.”

However, they added that the “logistics and cost” of the latter approach may be “significant barriers” for most birthing centers.

When examining late-onset GBS disease, Nanduri and colleagues found that incidence remained stable during the study period (mean 0.31 per 1,000 live births), with a case-fatality rate of 5.4% in full-term infants. Annual rates of late-onset disease were also higher among preterm infants versus term infants and for black versus white infants.

While no β-lactam resistance was identified, the authors said about 20% of isolates showed “constitutive clindamycin resistance.”

One limitation to the data was that the surveillance system only represents 10% of U.S. live births, and may not represent “the full variation within the country.”