Detection of New Delhi Metallo‐beta‐Lactamase and Extended‐Spectrum beta‐Lactamase Genes in Escherichia coli Isolated from Mastitic Milk Samples. Issue 5 (19th July 2013) - Ghatak, S.
Summary: In this study, eight Escherichia coli isolates were obtained from milk samples of dairy cattle suffering from clinical/subclinical mastitis. Isolates were characterized for antimicrobial resistance traits and virulence genes. Results revealed that one isolate was harbouring New Delhi metallo‐beta‐lactamase gene ( bla NDM ). Cloning and sequencing of the PCR amplicon confirmed the identity of the gene (GenBank accession no.KC769583 ) having 100% homology with bla NDM‐5 (GenBank accession no.JN104597.1 ), and this isolate was susceptible to colistin, chloramphenicol and tetracycline only. Moreover, another isolate carried extended‐spectrum beta‐lactamase (ESBL) gene – bla CTX‐M, and all isolates possessed bla TEM gene. Of the eight isolates, only one isolate was positive for shiga toxin gene ( stx2 ), and none were harbouring stx1 gene. Occurrence of New Delhi metallo‐beta‐lactamase ( bla NDM ) in one E. coli isolate and ESBL genes in other isolates poses a potential threat to human health following possible entry and spread through food chain.