LAUSR

Abstract Background Following international and anecdotal domestic reports of post-pandemic increases in incidence of brain abscesses, including from the United States (US), we investigated trends, patient demographics and microbial aetiology of hospital admissions for brain abscess in England. Methods National patient admissions data from NHS England Hospital Episode Statistics with an ICD10 code for brain abscess (G06.0/G06.2) between 2014 and 2023 were extracted. Data were linked to the UKHSA national laboratory surveillance database to identify microbiological specimens (blood, CSF, pus/abscess or selected nasopharyngeal) taken within -1 and 30 days of admission. Incidence and mortality trends were assessed by patient demographic and identified organism. Results Between 2014-2023, 11,011 brain abscess admissions were identified from 1775 (16.1%) children and 8553 (77.7%) adults (≥18y). Median age was 54y; 64.4% (n=7088) were men, 84.0% (n=7818) were of white ethnicity, lower in children compared to adults (71.5% vs 87.3% for adults). Brain abscess incidence in adults increased 42% between 2014 and 2023 (1.6 to 2.2/100,000 population), and for children 23% increase (1.5 to 1.7/100,000) particularly in extradural/subdural abscess (G06.2) since 2020, overtaking the rate in adults (figure 1). Microbiology data were available for 3545 cases (32.2%), with 316 and 109 different species identified in adults and children respectively. In adults, the most frequently identified species was Staphylococcus aureus (26.1%, n=1303; range 22-36%/year), followed by Streptococcus anginosus group (11.1%; n=590; range 9-16%/year; figure 2). In children, 23.6% cases had S. anginosus group identified (n=178; range 12-32%/year), followed by group A Streptococcus at 9.7% (n=73; range 0-18%/year; figure 3). Conclusion This is the first national study on brain abscess incidence and microbial aetiology in England. Brain abscess reports showed a marked increase since 2014, with dramatic increases in children since 2020, a similar picture to the US. The microbial aetiology differed between adults and children, with a greater diversity in adults. Differences between surgical and community acquisition and predisposing conditions need to be assessed to identify opportunities for prevention. Disclosures All Authors: No reported disclosures