July 17, 2020

Effectiveness of antibiotic prophylaxis effective at preventing iGAS in persons exposed to iGAS cases

Q#20-07 –Effectiveness of antibiotic prophylaxis effective at preventing iGAS in persons exposed to iGAS cases


Infection by Streptococcus pyogenes (group A streptococci, GAS) causes a wide range of syndromes ranging from localized illness, such as pharyngitis, to invasive and serious disease, including bacteremia, pneumonia, necrotizing fasciitis, and streptococcal toxic shock syndrome (STSS)1. Invasive GAS (iGAS) infection causes significant morbidity and mortality in both children and adults. An estimated of 9557 cases (3.8 cases per 100 000 persons per year) with 1116 deaths (case-fatality rate, 11.7%) resulting from invasive GAS occurred in the United States from 2005-2012. The risk of contracting iGAS disease is higher amongst close contacts of iGAS cases relative to other contacts or the general population. However, very few population-based studies have been published quantifying the risk of secondary household transmission. In a recent study in the UK, the authors suggested the use of selective prophylaxis for contacts with particular risk factors (pregnancy, women in the postpartum period, neonates, adults older than 75 years).


We will use two distinct data sources. The first one is MarketScan (2010-2018), a database that contains millions of healthcare claims information from large employers, managed care organizations, and Medicare program in the United States. The second source is the Quebec Pregnancy Cohort (QPC), an ongoing population-based cohort with prospective data collection on all pregnancies of women covered by the provincial prescription drug insurance that occurred between January 1998 and December 2015 in the province of Quebec. Data on the mothers and children after the end of pregnancy are also collected. Individual-level information is obtained from province-wide databases and linked using unique personal identifiers. QPC contains up to 17 years of follow-up for mothers and children.