Risk factors for acquisition of CTX-M genes in pilgrims during Hajj 2013 and 2014

Background: Mass gatherings, especially the Hajj pilgrimage, provide favourable conditions for bacterial transmission among participants, which might contribute to the international spread of ESBL-producing Enterobacteriaceae (ESBL-E). Objectives: Weconducted an analysis aimed at investigating risk factors for CTX-M gene (bla(CTX-M)) rectal carriage in 2013 and 2014 Hajj pilgrims. Methods: A total of 218 pilgrims provided paired pre- and post-Hajj rectal samples (2013, 129 pilgrims; 2014, 89 pilgrims). CTX-M genes in rectal samples were identified by PCR and confirmed by sequencing. Pilgrims' characteristics, including possible factors relating to ESBL acquisition, were collected and analysed using XLSTAT version 2016.05.34687 (Addinsoft). For the univariate analysis, the frequencies of nominal data were compared using Pearson's chi(2) test and Fisher's exact test, and the means of quantitative data were compared using Student's t-test. A difference was considered significant when P<0.05. For multivariate analysis, a logistic regression was carried out, considering all the significant data in univariate analysis. Results: The acquisition rates of CTX-M genes among pilgrims during the 2013 and 2014 Hajj were similar, at 31.0% and 34.83%, respectively. Being of Moroccan origin, having chronic conditions, shortness of breath or diarrhoea, and using beta-lactams were associated with higher CTX-M gene acquisition, while being of Algerian origin and using macrolides were associated with lower CTX-M acquisition in univariate analysis. Shortness of breath and diarrhoea remained associated with increased CTX-M gene acquisition and consumption of macrolides with lower CTX-M gene acquisition in multivariate analysis. Conclusions: The possible gut colonization by CTX-M-type ESBL bacteria should be taken into account when prescribing empirical antibiotic treatments for infections that occur in returning Hajj pilgrims.