Taxonomic diversity of antimicrobial-resistant bacteria and genes in the Red Sea coast Riaz Ullah a,b,1 , Muhammad Yasir a,c, ⁎ ,1 , Fehmida Bibi a,c , Turki S. Abujamel a,c , Anwar M. Hashem a,d , Sayed Sartaj Sohrab a,c , Ahmed Al-Ansari e , Abdulmohsin A. Al-Sofyani f , Ahmed K. Al-Ghamdi c , Abdulbasit Al-sieni b , Esam I. Azhar a,c a Special Infectious Agents Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia b Biochemistry Department, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia c Medical Laboratory Technology Department, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia d Department of Medical Microbiology and Parasitology, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia e Department of Environmental Sciences, Faculty of Meteorology, Environment and Arid Land Agriculture, King Abdulaziz University, Jeddah, Saudi Arabia f Marine Biology Department, Faculty of Marine Science, King Abdulaziz University, Jeddah, Saudi Arabia HIGHLIGHTS • Culturomics enhanced Red Sea bacterial diversity and retrieved novel candidate species. • Relatively high antibiotic resistance re- corded in the Red Sea • Increase number of multi-drug resistant bacteria found in offshore and coastal sites • Quantitatively more antibiotic resis- tance genes detected in frequented beaches GRAPHICAL ABSTRACT abstract article info Article history: Received 18 December 2018 Received in revised form 26 March 2019 Accepted 18 April 2019 Available online 22 April 2019 Editor: Ewa Korzeniewska Despite development of a record number of recreational sites and industrial zones on the Red Sea coast in the last de- cade, antibiotic-resistant bacteria in this environment remain largely unexplored. In this study, 16S rDNA sequencing was used to identify bacteria isolated from 12 sediment samples collected from the Red Sea coastal, offshore, and man- groves sites. Quantitative PCR was used to estimate the quantity of antimicrobial resistance genes (ARGs) in genomic DNA in the samples. A total of 470 bacteria were isolated and classified into 137 distinct species, including 10 candidate novel species. Site-specific bacterial communities inhabiting the Red Sea were apparent. Relatively, more resistant iso- lates were recovered from the coast, and samples from offshore locations contained the most multidrug-resistant bac- teria. Eighteen ARGs were detected in this study encoding resistance to aminoglycoside, beta-lactam, sulfonamide, macrolide, quinolone, and tetracycline antibiotics. The qnrS, aacC2, ermC, and bla TEM-1 genes were commonly found in coastal and offshore sites. Relatively higher abundance of ARGs, including aacC2 and aacC3, were found in the ap- parently anthropogenically contaminated (beach) samples from coast compared to other collected samples. In conclu- sion, a relative increase in antimicrobial-resistant isolates was found in sediment samples from the Red Sea, compared to other studies. Anthropogenic activities likely contribute to this increase in bacterial diversity and ARGs. © 2019 Elsevier B.V. All rights reserved. Keywords: Bacterial diversity Culture-dependent Antimicrobial resistance Red Sea Science of the Total Environment 677 (2019) 474–483 ⁎ Corresponding author at: Special Infectious Agents Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia. E-mail address: yasirkhattak.mrl@gmail.com (M. Yasir). 1 Authors equally contributed. https://doi.org/10.1016/j.scitotenv.2019.04.283 0048-9697/© 2019 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv