Emergence of class 1 to 3 integrons among members of Enterobacteriaceae in Egypt Dina E. Rizk a, * , Areej M. El-Mahdy a, b a Microbiology & Immunology Department, Faculty of Pharmacy, Mansoura University, Mansoura 35516, Egypt b Department of Pharmaceutical Sciences, College of Pharmacy, Princess Norah Bint Abdulrahman University, Riyadh 11671, Saudi Arabia article info Article history: Received 16 May 2017 Received in revised form 9 September 2017 Accepted 11 September 2017 Available online 21 September 2017 Keywords: Integron Enterobacteriaceae MDR Gene cassettes abstract In spite of the role of integrons as the main contributor to multidrug resistance worldwide, their prevalence in Egypt is still underestimated. In this work, we announce the emergence of class 2 and 3 integrons among Enterobacteriacae isolates from Mansoura University Hospitals. Ninety-three clinical isolates were obtained from different clinical sources, among which 70% of E. coli, 94.8% of K. pneumoniae and 85.7% of Enterobacter spp. were assigned to be multidrug resistant (MDR). Subsequently, the occurrence of class 1e3 integrons was confirmed by multiplex PCR. Class 1 integron was the most predominant being harbored by 42.8%, 90% and 25% of MDR E. coli, K. pneumoniae and Enterobacter spp. isolates, respectively. This was followed by class 2 and 3 integrons which were, for the first time, reported in these hospitals. Also, coexistence of integrons 1and 2 was revealed in 36.9% of integron positive isolates. A significant association was noticed only between resistance to gentamicin and integron prevalence among MDR E. coli isolates (P ¼ 0.02). In conclusion, this work represents the first report for detection of class 2 and 3 integrons, beside the previously detected class 1 integrons. This highlights the high incidence of integrons among MDR Enterobacteriacae isolates which indicates the selective pressure of antibiotics in these hospitals. Moreover, this study confirms the possibility of the use of integrons as markers for MDR identification. © 2017 Elsevier Ltd. All rights reserved. 1. Introduction Multidrug bacterial resistance caused by horizontal gene transfer leads to rapid dissemination of the genes responsible for the antibiotics to be ineffective among bacteria. MDR Gram- negative bacteria are considered a major cause of mortality among hospitalized patients [1,2]. Escherichia coli, Klebsiella pneu- moniae and Enterobacter spp. are members of Enterobacteriaceae that can be usually determined as causative agents of many hospital and community-acquired infections [3]. In hospital, immunocom- promised patients are liable to infections caused by one or more of these organisms [4]. Non-specific use of antibiotics has promoted a rapid propaga- tion of resistance to many organisms and causes a great problem for the future treatment of such bacterial infections. This bacterial reluctance has become a prime interest in public health worldwide, producing ineffectual clinical therapy and economic overload, and is straightway life-threatening [5]. Antibiotic resistance is carried on transposons, plasmids and gene cassettes in integrons, which are major participant to the prompt prevalence of drug resistance among bacterial pathogens, particularly in the family of Entero- bacteriaceae [6]. Integrons are non-mobile genetic elements carried out on transposons, plasmids or chromosome, so they could be easily transported among bacteria [7]. Consequently, integrons could be determined as one of the main causes of MDR dissemination [8]. Three integron classes had been identified according to amino acid sequences of IntI integrases as (IntI1, IntI2, and IntI3) that are known to be responsible for resistance to antibiotics [9]. Integrons belonging to Class 1 are the most predominant among bacteria [10]. Integrons are mainly composed of three major sites in the conserved segment (5 0 - CS): an intI gene encoding an integrase, a specific recombination site (attI) and a promoter that targets the transcription of the gene cassettes. An extra resistance gene, sul1, responsible for sulfonamide resistance is found in the 3 0 - CS in most class 1 integrons [11]. IntI2 and intI3 are found in Class 2 and 3 integrons and their products are 40 and 61% similar to class 1 * Corresponding author. E-mail addresses: dena@mans.edu.eg, dinaeid2013@yahoo.com (D.E. Rizk). Contents lists available at ScienceDirect Microbial Pathogenesis journal homepage: www.elsevier.com/locate/micpath https://doi.org/10.1016/j.micpath.2017.09.023 0882-4010/© 2017 Elsevier Ltd. All rights reserved. Microbial Pathogenesis 112 (2017) 50e56