Incidence of invasive infections with Group B streptococcus in adults in Norway 1996-2019: a nationwide registry-based case-control study

Invasive group B streptococcal infections in Western Australia, 2000-2018

BACKGROUND

Neonatal and puerperal sepsis are major manifestations of invasive group B streptococcal (Streptococcus agalactiae; iGBS) infections. International data indicate the importance of iGBS infections among non-pregnant adults.

AIMS

To describe the burden of iGBS infections in Western Australia (WA) between 2000 and 2018 in terms of incidence, length of hospitalisation and all-cause 30- and 90-day mortality.

METHODS

This was a retrospective, population-based study using linked data from the state government-owned pathology provider, hospitalisations and death registrations. Children and adults with isolation of GBS in a normally sterile site or a hospital-based diagnosis of iGBS infection were included.

RESULTS

There were 2861 cases; just over a quarter (n = 768) were aged 0-1 year. Half of the cases were among females (1438 of 2861), and the median age was 39 years. Incidence increased over the study period, with an age- and sex-adjusted incidence rate ratio for year of 1.08 (95% confidence interval (CI) 1.06-1.09). The incidence in 2018 was 9.5 cases (95% CI 8.3-10.6 cases) per 100 000 population. The proportion of cases among those aged 0-1 year fell across the period, while the relative incidence in older age groups increased. The median length of hospital stay was 7 days (interquartile range 4-15 days), and mortality at 30 days was 3% (95 of 2861).

CONCLUSIONS

iGBS cases increased across the period 2000-2018 in WA, with older adults making up a higher proportion of cases over time. Preventive efforts among older patients, including potentially through vaccination, may reverse this increase.

Group B Streptococcus Infections in Non-Pregnant Adults, Italy, 2015-2019

Group B Streptococcus (GBS, Streptococcus agalactiae) is a pathogen of increasing importance in adults. Severe and invasive cases in non-pregnant adults were collected during the period 2015-2019 by voluntary-based surveillance. In total, 108 GBS strains were phenotypically and genotypically characterized for the serotype, antimicrobial resistance, pili, surface protein genes, and the hyper-virulent adhesin hvgA. Patients were divided into two age groups: adults (18-64 years; n = 32) and older adults (≥65 years; n = 72). The average age was 70.8 years, with a male/female ratio of 1.7. Most isolates were recovered from cases of bacteremia (blood, n = 93), and a higher frequency of invasive GBS infections (iGBS) was found among older adults (66.7%). Serotype III was the most frequent (n = 41, 38%), followed by type Ia and type V (n = 20 each, 18.5%). Serotypes Ia, Ib, II, III, IV, and V accounted for all but one isolates (99.1%). The iGBS isolates were universally susceptible to penicillin, while the prevalence of resistance to clindamycin, erythromycin, tetracycline, and high-level gentamicin resistance was 26.8%, 24.1%, 85.2%, and 5.5%, respectively, with the predominance of the erm(B) gene for macrolide resistance and the tet(M) gene for tetracycline resistance. The associations between the serotypes/antimicrobial resistance/virulence traits underlined the increasing importance of serotype III and its contribution to antimicrobial resistance as well as the steady increase over time of serotype IV. This nationwide study confirmed the need for monitoring the GBS epidemiology in non-pregnant adults through continuous surveillance of GBS infections.