6 Bacterial epidemiology of appendicitis reveals no seasonal trends in a large cohort
Dareilena Karaviti, Nikita Jolapara, Wajid Jawaid, Iain Yardley
Evelina London Children's Hospital, London, United Kingdom



Acute appendicitis in childhood is associated with a variety of bacteria. Previous studies have suggested seasonal variation in the organisms involved. If this phenomenon was confirmed, it may have implications for the microbiological management of children with acute appendicitis.

We aimed to assess the frequency of different bacterial species occurring in acute appendicitis, their rates of co-occurrence and any annual seasonal variation in a large cohort over an extended period.


Our hospital database was interrogated using ICD-10 and OPCS codes for all patients under the age of 18 diagnosed with acute appendicitis or undergoing appendicectomy between January 2006 and December 2017. Exclusion criteria included incidental appendicectomy, miscoded operations and no microbiological sample sent for analysis. Data collected included patient demographics, date of admission, blood results, operative findings, histological diagnosis, microbiology analysis and length of stay. Data was explored using the R language for statistical computing.


Over 12-years 916 patients were identified.  29 miscoded, 7 incidental appendicectomies and 481 with no microbiology sample sent were excluded. 398 patients had acute appendicitis and a microbiological sample sent.  140 had no bacterial growth, leaving 258 patients with positive cultures. The commonest bacteria were Escherichia coli (174, 67%), Streptococcus milleri (120, 47%), Pseudomonas aeruginosa (56, 22%) and Bacteroides (51, 20%). Cardinality was greatest for intersections between the largest sets suggesting no dependencies between the different microbial species. The figure shows an apparent seasonal trend in both monthly rates of appendicitis and the growth of S. milleri but relative numbers of Strep. Milleri by month were not significantly different (p = 0.52, Asymptotic Wilcoxon-Mann-Whitney Test).


We report no evidence of seasonal variation in microbiological analysis in acute appendicitis. Anti-microbial prophylaxis and treatment in acute appendicitis should follow local guidelines based on known susceptibilities and require no seasonal adjustment.