Discussion
Among patients treated for necrotising soft tissue infection in the head and neck region at Rikshospitalet, group A streptococci were isolated in 18 of 25 during the nearly two years following the COVID-19 pandemic, compared with 8 of 21 in the approximately three years preceding the pandemic. Several countries have reported a post-pandemic increase in the incidence of necrotising soft tissue infections (7–9), including Sweden, where infection control measures were less restrictive than in Norway (7, 9).
The cause of this increase remains unclear, but possible contributing factors include reduced herd immunity to group A streptococci due to lower exposure during the pandemic, changes in bacterial virulence factors and increased susceptibility to bacterial infections following COVID-19 infection (12–14).
Beta-lactam resistance in group A streptococci is extremely rare. As all strains in our study were susceptible to penicillin, resistance development does not appear to explain the post-pandemic hospitalisations for necrotising soft tissue infections. No clindamycin-resistant group A streptococci were found in our material. In light of the 2023 NORM report, which documented 2.9 % clindamycin resistance among 382 blood culture isolates, we consider this a minor issue in the context of clinical empirical treatment (15). In December 2022, the national guidelines for antibiotic use in hospitals were revised, recommending piperacillin–tazobactam and clindamycin for severe soft tissue infections in the head and neck region (16). Antibiotic use at our department was in line with current guidelines throughout the study period.
In terms of age, sex and comorbidity, we found no obvious variation among patients before, during or after the pandemic (Table 1). In South-Eastern Norway Regional Health Authority, patients with necrotising soft tissue infections of the head and neck are primarily treated at the Department of Otorhinolaryngology, Oslo University Hospital, Rikshospitalet. During the relatively short study period, no changes were made to the catchment area or referral procedures, nor were any new diagnostic criteria established. It is therefore unlikely that the results were influenced by changes in clinical practice or patient selection.
The study's limitations include its retrospective design and reliance on data extracted from unstructured patient records. Data were limited to the South-Eastern Norway Regional Health Authority catchment area, and there were therefore few patients in each period. Consequently, no conclusions can be drawn regarding changes in incidence, and the results should be interpreted with caution. We believe the findings are, nevertheless, interesting. To the best of our knowledge, no other data have been published on this patient group in Norway during the same period, and the medical community has called for further studies on this population (6).
Even after intensive and comprehensive treatment, patients with necrotising soft tissue infections experience significant morbidity and mortality. National prospective studies, involving collaboration across health regions, medical specialties and expert groups, are needed to improve understanding of the aetiology, refine diagnostics and develop more effective treatment for these severely ill patients.