Choosing Wisely: Effectiveness and Safety of Antibiotic Prophylaxis in Close Contacts of Invasive Group A Streptococci Infection
Read article: Submitted by: Dr Tony WallsChristchurch Hospital, New ZealandBackground:In 2022 the CDC guidelines began recommending the use of antimicrobialprophylaxis to close contacts of patients with invasive Group A Streptococcal (iGAS) infections. There is limited evidence to support this approach and the study by Birck et al. explores the effective-ness and safety of antibiotic prophylaxis. Utilizing data from the MarketScan database (2010–2019), the authors assessed infection rates and adverse events associated with antibiotic prophylaxis in the first 30 days following the diagnosis of infection in the index case.Key Findings:1. Effectiveness: The study found no significant difference in GAS infection rates be-tween individuals who received prophylactic antibiotics and those who did not. The crude infection rate was 13.2 per 1000 person-years for antibiotic users and 14.8 per 1000 person-years for non-users. The adjusted odds ratio was 0.88 (95% CI: 0.12–6.51), indicating no clear protective effect of antibiotics.2. Adverse Events: There was a three-fold increase in adverse drug events among those who received antibiotics (39.6/100 person-years) compared to those who did not (10.6/100 person-years).3. Population Characteristics: The cohort included 21,032 close contacts, with only 4.4% receiving antibiotics. Factors such as comorbidities and steroid use were adjust-ed for in the analysis.Strengths:• Large cohort size and comprehensive data collection through administrative claims.• Rigorous control for confounding factors, including comorbidities and recent infec-tions.• Use of laboratory-confirmed iGAS cases and ICD-9/10 codes for accurate case identi-fication.Limitations:• Reliance on administrative claims data, which may introduce misclassification bias.• Follow up was limited to 30 days Clinical Implications:This study challenges current public health guidelines recommending antibiotic prophylaxis for close contacts of iGAS cases. The lack of a clear protective effect, combined with the in-creased risk of adverse events, underscores the need for a more tailored approach. Selective prophylaxis for high-risk groups, such as immunocompromised individuals or those with chronic conditions, may be more appropriate.
1. A study evaluating the use of antibiotic prophylaxis in close contacts of invasive group A streptococcal (iGAS) infection analysed infection rates and adverse events over a 30-day pe-riod.
Which of the following best describes the study’s conclusion regarding prophylactic antibi-otic use?
A.
A) While antibiotic prophylaxis reduced secondary GAS infections in high-risk individuals, it was associated with a significantly increased rate of adverse drug reactions.
B.
B) The study found no statistically significant reduction in GAS infection rates among close contacts receiving prophylaxis, and those who received antibiotics experienced a substantially higher incidence of adverse drug events.
C.
C) Antibiotic prophylaxis was only effective when administered within 48 hours of the index case diagnosis, with delayed administration showing no benefit.
D.
D) The study recommended universal antibiotic prophylaxis for all close contacts due to the potential severity of iGAS infections, despite concerns about antibiotic resistance.
