Increase in Oral Streptococcal Endocarditis Among Moderate-Risk Patients: Impact of Guideline Changes on Endocarditis Prevention

Background: The well-established connection between oral bacteria and infective endocarditis (IE) has prompted discussions about using antibiotic prophylaxis (AP) before invasive dental procedures. In 2007/2008, guidelines restricted AP from moderate and high-risk to exclusively high-risk patients.

Objectives: The authors aimed to assess whether the proportion of oral streptococcal IE increased in moderate-risk patients using University Hospital Zurich data from 2000 to 2022.

Methods: Adult IE patients were categorized into risk groups based on European Society of Cardiology and Swiss guidelines. The investigation focused on analyzing the proportion of oral streptococcal IE across different risk groups in two distinct periods (1: 2000-2008; 2: 2009-2022). Logistic regression models, adjusted for various factors, were employed.

Results: Of 752 IE cases, 163 occurred in period 1, and 589 in period 2. Oral streptococci caused 22% of cases. Proportions of streptococcal IE in period 1 versus period 2 were 24% versus 16% in high-risk, 24% versus 39% in moderate-risk, 33% versus 7% in low-/unknown-risk, and 18% versus 14% in no-risk patients. Compared to the other risk groups, the moderate-risk group had a 22% higher chance of oral streptococcal IE in period 2. After multivariable adjustment, moderate-risk patients had twice the risk of oral streptococcal IE compared to period 1 (OR: 2.59 [95% CI: 1.16-5.81]). Among moderate-risk conditions, congenital valve anomalies were associated with oral streptococcal IE (unadjusted OR: 2.52 [95% CI: 1.71-3.71]).

Conclusions: Oral streptococcal IEs increased in the moderate-risk group of patients after the AP guideline change. Exploring the potential necessity for expanding AP indications to certain patient groups with congenital valve anomalies may be warranted.