High incidence of multidrug-resistant Escherichia coli coharboring mcr-1 and bla CTX-M-15 recovered from pigs

• Published in: Infection and drug resistance 2019, Vol.12, p.2135-2149
• Main Authors: Shafiq, Muhammad, Huang, Jinhu, Ur Rahman, Sadeeq, Shah, Jan Mohammad, Chen, Li, Gao, Yi, Wang, Mengli, Wang, Liping
• Format: Article
• Language: English
• ISSN: 1178-6973; 1178-6973
• DOI: 10.2147/IDR.S209473

The coexistence of mobile colistin (COL)-resistant gene with extended-spectrum beta-lactamase (ESBL) gene in has become a serious threat globally. The aim of this study was to investigate the increasing resistance to COL and in particular its coexistence with ESBL-producing recovered from pig farms in China. were isolated from 14 pig farms in Jiangsu China. Susceptibility testing was identified by micro-dilution method. PCR assay and nucleotide sequencing were used to detect COL-resistant genes, -1 to -5, as well as ESBL genes, , and . Conjugation experiment, plasmid replicon typing of the multidrug resistance (MDR), S1-PFGE and DNA southern hybridization were performed to study the transferability of these genes. Overall, 275 isolates were recovered from a total of 432 cloacal and nasal swabs. More than 90% of the isolates were MDR, of which 70.18% were resistant to COL. Of these 275 isolates, was identified as the most predominant gene carried by 71.63% (197/275) of isolates, 39.59% (78/197) of the isolates were harboring both and ESBL genes ( and ). ESBL genotyping showed that was the most predominant ESBL (68.49%) followed by (16.4%) and (15%). Sequencing revealed that the most common variants of identified were, (69%), (29%) and (1.8%). IncHI2, IncFIB, IncFIC, IncN and IncX4 were found to be the most common Inc-types found both in donors and in transconjugants and were associated with the transfer of the and ESBL encoding genes. Six strains carried a total of five different plasmids: approximately 97-, 130-, 160-, 227- and 242-kb plasmids. The coexistence of the and -carrying isolates displaying high MDR, recovered from of pig origin, is a major concern for both humans and veterinary medicine.