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. 2025 Mar;55(3):453-460.
doi: 10.1111/imj.16611. Epub 2025 Jan 8.

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

Cameron M Wright  1   2   3 , Rachael Moorin  2   3 , John Dyer  1 , Jonathan Carapetis  2   4   5 , Laurens Manning  1   2   4
Affiliations

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

Cameron M Wright et al. Intern Med J. 2025 Mar.

Abstract

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.

Keywords: group B streptococcus; infectious disease; invasive disease; public health; streptococcus.

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Figures

Figure 1
Figure 1
Age‐standardised incidence of invasive group B streptococcal disease in Western Australia, 2000–2018. The baseline age distribution is the year 2000. The error bars are 95% confidence intervals. (formula image), Invasive group B streptococcal disease; (formula image), confirmatory pathology sample.
Figure 2
Figure 2
Age group distribution of invasive group B streptococcal disease in Western Australia, 2000–2018. (formula image), Invasive group B streptococcal disease; (formula image), microbiological confirmation.
Figure 3
Figure 3
Indigenous versus non‐indigenous distribution of group B streptococcal disease in Western Australia, 2000–2018. (formula image), Indigenous; (formula image), non‐indigenous.
See this image and copyright information in PMC

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