Enterobacter cloacae Complex Isolated from Shrimps from Vietnam Carrying bla _IMI-1 Resistant to Carbapenems but Not Cephalosporins

Abstract

I n August 2017, batches of Penaeus monodon (Asian tiger shrimp) and P. vannamei (White leg shrimp), originating from fish farms in Vietnam, were screened for the presence of carbapenemase-producing Enterobacteriaceae (CPE). An Enterobacter cloacae complex was isolated on a Chrom ID carba plate (bioMérieux Benelux BV), designated 3568. Susceptibility testing was performed according to ISO 20776-1:2006 with Sensititre panels EUVSEC and EUVSEC2 (Thermo Fisher, Waltham, MA, USA). Results are shown in Table 1. Interestingly, the isolate was resistant to ampicillin, cefoxitin, and carbapenems but not to third-and fourth-generation cephalosporins. No resistance to other antibiotics was measured. DNA was isolated using a Gentra Puregene kit (Qiagen), and whole-genome sequencing was performed using MiSeq sequencing (Illumina). Contigs were compared to data in the Resfinder database, identifying bla IMI-1 as the only resistance gene (1). Comparison to other Enterobacter isolates encoding bla IMI-1 indicated that the gene is present on an EcloIMEX putative mobile genetic element (2). It is hypothesized that the EcloIMEX elements may be able to exit the chromosome through recombination mediated by the XerD/C recombinases, though this remains to be shown (3). The EcloIMEX element of strain 3568 was 99.94% identical to the element previously described in Enterobacter cloacae complex isolate DS31788 and is named here "EcloIMEX-7" (4). EcloIMEX-1 encodes the carbapenemase bla NMC-A , whereas EcloIMEX-2 to-7 encode bla IMI-1. Most carbapenemases have hydrolytic activity against third-and fourthgeneration cephalosporins, and several studies have reported carbapenem-resistant but cephalosporin-susceptible isolates (3-6). Although this is not completely unexpected considering the lower affinity that some of these enzymes have for these molecules (7), it is a trend that requires attention in monitoring and diagnostics in the clinic as mutants that are resistant due to increased expression may evolve rapidly when selected for by the presence of cephalosporins. So far, EcloIMEX elements encoding IMI-1 have been found in 21 strains of 16 different multilocus sequence types (MLSTs) from Canada and China (4, 5). The isolate described here belongs to ST411 and is unrelated to the strains mentioned above, although the EcloIMEX-7 element is nearly identical to some of the elements previously described. This indicates that the EcloIMEX elements seem to spread among genetically diverse Enterobacter strains and may be mobilized through some mechanism for

Dissemination of carbapenemase-producing Enterobacteriaceae harbouring blaNDM or blaIMI in local market foods of Yangon, Myanmar

“…We isolated a bla IMI-1 -harbouring E . coloacae complex from fish and water spinach, which is usually cultivated in water-rich regions, corroborating previous reports that associated these bacteria with aquatic environments 6,21,22 . Of note, we isolated two water spinach isolates of the same ST and EcloIMEX type from different districts, suggesting the existence of a shared reservoir of bla IMI-1 dissemination.…”

The European Union Summary Report on Antimicrobial Resistance in zoonotic and indicator bacteria from humans, animals and food in 2017/2018

“…Due to the public health importance of carbapenemase-producing E. coli and/or Salmonella, both as pathogens and as vectors for resistance mechanisms there is a need to follow further developments in this area for farm animals and food derived thereof. Especially as carbapenemase-producing Enterobacteriaceae has been reported, not only in farm animals and food derived thereof but also from vegetables from many parts of the world including Europe (Zurfluh et al, 2015;Touati et al, 2017;Brouwer et al, 2018;K € ock et al, 2018;Liu et al, 2018;Irrgang et al, 2019).…”

Novel Carbapenemases FLC-1 and IMI-2 Encoded by an Enterobacter cloacae Complex Isolated from Food Products

“…Often, these genes are chromosomally located in nonpathogenic aquatic bacterial species, limiting them as relevant threats for the general population (3). However, more recent studies screening seafood imported from Southeast Asia have found carbapenemases encoded in human pathogens or on conjugative plasmids (4–6). As such, seafood imported from countries with high carbapenemase prevalence may need to be included in monitoring programs.…”

“…Proteins with carbapenemase activity fall into the three major Ambler classes A, B, and D β-lactamases (7). Genes of these classes have been described on mobile genetic elements, such as plasmids and chromosomally integrated elements, which adds to the concerns regarding these genes because they facilitate the spread of these genes among both commensal and pathogenic bacteria (6, 8, 9). The family of Enterobacteriaceae consists of many commensal, opportunistic, and infectious species that can readily exchange genetic material.…”