Seasonal variations in use and outcome of rapid antigen detection tests and cultures in pharyngotonsillitis: a register study in primary care

The impact of social restrictions on the incidence and microbiology of peritonsillar abscess: a retrospective cohort study

OBJECTIVES

We aimed to explore the impact of social distancing on the incidence and microbiology of peritonsillar abscess (PTA).

METHODS

We performed a cross-sectional analysis of all patients with PTA and their microbiological findings in the 2 years preceding versus the 2 years following the COVID-19 lockdown in Denmark (11 March 2020), who were admitted to the Ear-Nose-Throat Department, Aarhus University Hospital. Age-stratified population data for the catchment area were obtained from Statistics Denmark.

RESULTS

The annual incidence rate was significantly higher in the 2-year period before (21.8 cases/100 000 inhabitants) compared with after (14.9 cases/100 000) the lockdown (p < 0.001). The number of cases with growth of Streptococcus pyogenes was significantly higher in the period before (n = 67) compared with after (n = 28) the lockdown (p < 0.001), whereas the number of cases positive for Fusobacterium necrophorum (n = 60 vs. n = 64) and streptococcus anginosus group (SAG) (n = 37 vs. n = 43) were stabile (p 0.79 and p 0.58, respectively). The relative prevalence of S. pyogenes was significantly higher in the period before (67/246 cultures, 27%) compared with after (28/179, 16%) the lockdown (p 0.007). On the contrary, the relative prevalence of F. necrophorum and SAG is significantly lower before (60/246, 24% and 37/246, 15%) compared with after (64/179, 36% and 43/179, 24%) the lockdown (p 0.013 and p 0.023).

DISCUSSION

Social distancing had a significant impact on the incidence and microbiology of PTA. Our findings suggest that S. pyogenes-positive PTA is highly related to direct social interaction, and represents a contagious pathogen. By contrast, PTA development caused by F. necrophorum and SAG is unrelated to direct social interaction and may be derived from flora imbalance.

[Disproving the myth of "abscess weather" predisposing to peritonsillitis and peritonsillar abscess]

BACKGROUND

Peritonsillar abscess (PTA) is often seen as a complication of acute tonsillitis and is defined as pus retention between the tonsillar capsule and the peritonsillar tissue. The etiology and pathogenesis have not yet been fully elucidated. A connection between certain weather conditions and temperature fluctuations and the occurrence of abscesses in the head and neck region has been discussed for years. The question here is whether higher temperature fluctuations are predisposing for the formation of abscesses.

MATERIALS AND METHODS

A retrospective evaluation of all patients hospitalized with peritonsillitis or PTA in the Department of Otorhinolaryngology of the Klinikum Rechts der Isar of the Technical University of Munich during a period of 10 years (2012-2021) was performed. Each patient was individually correlated with daily temperature data from the statistical meteorological office of the City of Munich.

RESULTS

A total of 1450 patients were included, 270 patients (18.62%) with peritonsillitis and 1180 patients (81.38%) with PTA. A correlation between the occurrence of peritonsillitis or PTA and major temperature fluctuations could be excluded in this large patient population. Moreover, a similar frequency of peritonsillitis and PTA was seen throughout the year.

CONCLUSION

The myth of a temperature dependence of the development of peritonsillitis or PTA and a so-called abscess weather could be negated in this study.

Seasonal variations and risk factors of Streptococcus pyogenes infection: a multicenter research network study

Background:

Streptococcus pyogenes, or Group A Streptococcus (GAS), causes acute pharyngitis and necrotizing fasciitis. Seasonal variations in GAS infections are not robustly characterized. We assessed seasonal variations and risk factors of GAS pharyngitis and ICD-10-diagnosed necrotizing fasciitis.

Methods:

From the period 2010–2019, we conducted a case–control study using laboratory-confirmed cases of GAS pharyngitis and a descriptive observational study of necrotizing fasciitis using ICD-10 codes. Data were collected from TriNetX, a federated research network. We extracted seasonal (quarterly) incidence rates. We used an autoregressive integrated moving average (ARIMA) model to assess seasonal variations. Demographic characteristics and 1-month outcomes were compared among adults with or without GAS pharyngitis.

Results:

We identified 224,471 adults with GAS pharyngitis (test-positive) and 546,142 adults without it (test-negative). GAS pharyngitis adults were younger (25.3 versus 30.2 years of age, p < 0.0001), more likely to be Hispanic individuals (10% versus 8%, p < 0.0001) and slightly more likely to be Black or African American individuals (14% versus 13%, p < 0.0001). Propensity score matching found that adults with test-positive cases of GAS pharyngitis had a higher risk of acute rheumatic fever while having no significant differences in risk of intensive care unit admission and mortality compared with test-negative cases. GAS pharyngitis average incidence peaked in the winter while dipping in the summer (0.32 versus 0.18 and 4.07 versus 1.78 per 1000 adults and pediatric patients, respectively). Necrotizing fasciitis diagnoses were highest during summer (0.032 per 1000 adults). There was a significant ARIMA seasonal variation in the time series analysis for adult and pediatric GAS pharyngitis (p < 0.0001 and p = 0.014, respectively). Necrotizing fasciitis diagnosis was not associated with seasonal variation (p = 0.861).

Conclusion:

Peaks in GAS pharyngitis occur in the winter months. ICD code–based necrotizing fasciitis did not show a quarterly seasonal variation.