P2-146 Comparative Genomics of Blactx-M-65-resistant Clinical Strains of Salmonella enterica serovar Infantis from Peru and Resistant Strains from Chicken, Cattle and Humans

Tuesday, July 11, 2017
Exhibit Hall (Tampa Convention Center)
Gopal Gopinath , U.S. Food and Drug Administration , Laurel , MD
Hannah Chase , U.S. Food and Drug Administration , Laurel , MD
Jayanthi Gangiredla , U.S. Food and Drug Administration , Laurel , MD
Isha Patel , U.S. Food and Drug Administration , Laurel , MD
Nicole Addy , U.S. Food and Drug Administration , Laurel , MD
Junia Jean-Gilles Beaubrun , U.S. Food and Drug Administration , Laurel , MD
Baoguang Li , U.S. Food and Drug Administration , Laurel , MD
Christopher Elkins , U.S. Food and Drug Administration , Laurel , MD
Flavia Negrete , U.S. Food and Drug Administration , Laurel , MD
Samantha Finkelstein , U.S. Food and Drug Administration , Laurel , MD
HyeJin Jeong , U.S. Food and Drug Administration , Laurel , MD
ChaeYoon Lee , U.S. Food and Drug Administration , Laurel , MD
Kyuyoung Han , U.S. Food and Drug Administration , Laurel , MD
Shaohua Zhao , U.S. Food and Drug Administration , Laurel , MD
Gregory Tyson , U.S. Food and Drug Administration , Laurel , MD
Heather Tate , U.S. Food and Drug Administration , Laurel , MD
Drake Tilley , U.S. Naval Medical Research Unit No. 6 , Callao , Peru
Mark Simons , U.S. Naval Medical Research Unit No. 6 , Callao , Peru
Andrea McCoy , U.S. Naval Medical Research Unit No. 6 , Callao , Peru
Rina Meza , U.S. Naval Medical Research Unit No. 6 , Callao , Peru
Allison Brown , Centers for Disease Control and Prevention , Atlanta , GA
Cindy Friedman , Centers for Disease Control and Prevention , Atlanta , GA
Ben Tall , U.S. Food and Drug Administration , Laurel , MD
Introduction: Extended-spectrum β-lactamase (ESBL) genes are capable of hydrolyzing commonly used β-lactam antibiotics, including third-generation cephalosporins reserved for treatment of severe infections.

Purpose: A detailed genomic comparison of Peruvian clinical Salmonella enterica serovar Infantis strains bearing a blaCTX-M 65 (cefotaximase) gene in relation to similar strains from environmental and food sources is presented.

Methods: Three hundred twenty-two clinical S. Infantis strains were obtained from patients with diarrhea from 1997-2014, representing a network of 13 Peruvian hospitals. These strains were characterized using PCR; microarray; whole genome sequencing (WGS); whole genome core gene (wgCGA) with 2700+ Salmonella core gene loci; kSNP3; in-house R; and ResFinder analyses for blaCTX-M-65 genes.  Serotype was confirmed with SeqSero, Premitest, and microarray.

Results: Results showed that 206 (64%) of the strains associated with 6 different hospitals were PCR-positive for blaCTX-M-65 which was confirmed by WGS in 26 strains. Other antibiotic resistance genes: blaCTX-M- 15; blaSHV-129; blaOXA-2; blaTEM-1B; and blaCTX-M-2 were also noteworthy. Genomic reconstruction revealed a highly conserved, previously reported 320 kb plasmid in all blaCTX-M-65-positive strains. For comparison, other S. Infantis genomes (100+) of environmental, animal, and human origin were obtained from NCBI; intra-serovar differences were seen with these strains compared to Peruvian clinical strains. Microarray, wgCGA and kSNP3 separated the S. Infantis strains into distinct clusters. Microarray analysis, which included the mobilome region, provided a higher resolution of blaCTX-M-65 S. Infantis strains. Genomic characterization showed that the blaCTX-M 65 genes among these Peruvian clinical S. Infantis strains were comparable to resistant strains from environmental and animal origin.

Significance: High similarity between blaCTX-M-65 positive S. Infantis strains from hospitals, and other sources, is a matter of concern for public health. The results of the study demonstrate a need to expand genomic targets to detect blaCTX-M-65-resistant strains including those associated with the food supply.