Increased disease severity in patients with appendicitis who grow Streptococcus anginosus

Author(s):

Allison R. Wilcox; Olivia Sacks; Laura Baumann; Eleah Porter; Kenneth Burchard; D. Josh Mancini

Background:

Streptococcus anginosus (SA), formerly S. milleri, are a subgroup of normal gut flora with pathogenic propensity toward abscess formation. There is a paucity of published literature on the clinical significance of growing SA in the context of intra-abdominal infection, and the preponderance of data is both in pediatric populations and in Europe. The aim of this study was to evaluate the clinical significance of SA in the setting of appendicitis at a tertiary care center in New England.

Hypothesis:

We hypothesized that patients who grow SA on intra-abdominal or pelvic fluid culture associated with appendicitis will experience worsened disease severity, defined by increased length of stay, higher readmission rate, and/or longer antibiotic duration.

Methods:

Single-institution, retrospective, case-control study of all adult patients (≥18) with International Classification of Diseases – 9th and 10th Revision code for appendicitis, and corresponding intra-abdominal or pelvic fluid culture from 10/1/2012-9/30/2017. Charts were reviewed to confirm clinical evidence of appendicitis and if none found, patients were excluded. Study end-point was set at one year from initial encounter at our institution and those with insufficient data were excluded. Univariate analysis of disease severity measures and positive culture for SA [SA(+)] was performed.

Results:

Eighty-one patients met inclusion criteria, of whom 28 (34.5%) were SA(+). There was no significant difference between SA(+) and SA(-) patients in terms of age or gender. Although we found no difference in the initial encounter length of stay between groups, SA(+) patients were significantly more likely to be readmitted (53.6% vs 20.8%, p=0.005) and undergo longer antibiotic duration (22.0 vs 11.9 days, p<0.001) (Table 1).

Conclusions:

The growth of SA in an appendicitis-related intra-abdominal or pelvic fluid culture is significantly associated with a higher readmission rate and longer duration of antibiotics. Further analysis of intra- and post-operative complications that may be associated with the growth of SA is warranted.