ESBL-Producing Escherichia coli from Cows Suffering Mastitis in China Contain Clinical Class 1 Integrons with CTX-M Linked to ISCR1

Abstract

The prevalence of pathogenic multi-drug resistant (MDR) extended-spectrum β-lactamase (ESBL)-producing Escherichia coli is rapidly increasing, becoming a global concern. In a veterinary context, ESBL-producing E. coli are mostly reported in poultry and pigs. Here, we report on the prevalence and characterize ESBL-producing E. coli isolated from diverse dairy farms in China. Overall, 36 (23.53%) out of 153 E. coli isolates from mastitic milk samples (n = 1252) were confirmed as ESBL-producers by double-disc synergy testing and PCR. Nucleotide analysis of PCR amplicons revealed that blaCTX-M was the predominant ESBL gene detected in 28 (77.78%) isolates, with blaCTX-M-15 being the major (78.57%) allele encoding for ESBLs. Also, 20 (55.56%) and 6 (16.67%) of the ESBL isolates were carrying blaTEM and blaSHV genes, respectively, in singlet or in combination. The majority of these isolates belonged to phylo-group A (69.44%) and D (16.67%). Strikingly, all these isolates were found to be MDR showing high resistance to cephalosporins including the fourth generation cefepime and common non β-lactams. Additionally, class 1 integrons (intI1) were found in 30 (83.33%) isolates. Analysis of the class 1 integrons variable regions indicated that they were carrying up to five different gene cassettes conferring resistance to various drugs with a predominant combination of dfrA17-aadA5 genes in tandem, conferring resistance to aminoglycosides and trimethoprim. However, no ESBL encoding genes were found in the cassettes. Interestingly, 22 (66.11%) of the ESBL isolates were also carrying insertion sequence common region 1 (ISCR1) which was found to be associated with most of the CTX-M genes. Altogether, the current study reports on the high prevalence of ESBL-positive E. coli, particularly CTX-M-15, carrying clinical class 1 integrons and ISCR1 elements are likely indicative of their rapid and wider dissemination, posing threats to veterinary and public health. To the best of our knowledge, this is the first comprehensive study to report on the alarming high occurrence of ESBL-producing E. coli from mastitic cows in China.

Molecular characterization of multidrug-resistant Klebsiella pneumoniae and Escherichia coli harbouring extended spectrum beta-lactamases and carbapenemases genes at a tertiary hospital, Kenya

“…Apart from humans the environment as well as animals that are a food source serve as reservoirs for ESBLs and studies done on different continents have documented evidence, which in part explains the global presence and spread of ESBLs (1,2,12).…”

An update on environmental mastitis: Challenging perceptions

“…Similarly, in Canada, ESBL was not detected among 394 E. coli and 139 Klebsiella isolates from bovine milk (Saini et al., ). By contrast, in China, almost a quarter of E. coli isolates from bovine mastitis were ESBL‐producing coliforms (Ali et al., ). In the UK and the Netherlands, presence of ESBL‐coliforms has been linked to presence or use of 3/4GC in waste milk and slurry (Gonggrijp et al., ; Randall et al., ).…”

Multidrug Resistant Carbapenemase-Producing Escherichia coli from Chicken Meat Reveals Diversity and Co-Existence of Carbapenemase Encoding Genes

“…Co-occurrence of different carabepenemases or combination of carbapenemase with other resistance conferring elements has been associated with potentially increased spectrum of resistance in Enterobacteriaceae (Sattar et al, 2016) including increased minimum inhibition concentration levels against carbapenems (Meletis, 2016). Elements such as insertion sequence common region 1 (ISCR1), conjugative plasmids and integrons have been found involved in mobilization and fast dissemination of resistance conferring elements including carbapenemase encoding genes (Ali et al, 2016).…”

“…Genotypic screening of carbapenemase-encoding enzymes: Bacterial DNA from MDR E. coli was isolated by boiling method as described earlier (Ali et al, 2016). PCR assay was used for detection of NDM-, KPC-, OXA-48-, VIM-and IMP-encoding genes as described previously using specific primers and cited in Sup.…”