We describe here the complete genome sequence of an Enterobacter hormaechei ST279 coharbouring bla_VIM-1 and mcr-9 recovered from uncooked beef patty in June 2017, Egypt. The tested isolate was resistant to carbapenem but susceptible to colistin (minimum inhibitory concentration (MIC), 0.5 μg/mL). The antimicrobial susceptibility profile and conjugation experiments were performed. The entire genome was sequenced by the Illumina MiniSeq and Oxford Nanopore methods. The bla_VIM-1 and mcr-9 genes are carried on the same IncHI2/pMLST1 plasmid, pMS37a (Size of 270.9 kb). The mcr-9 gene was located within the physical boundaries demarcated by two insertion elements IS903 (upstream) and IS1 (downstream) but did not possess the downstream regulatory genes (qseC/qseB) which regulate the expression of mcr-9. Therefore, the mcr-9 might be silently disseminated among carbapenem-resistant Enterobacterales. In addition to bla_VIM-1 and mcr-9, plasmid pMS37a harbored various antibiotic resistance genes including aac(6’)-Il, ΔaadA22, aac(6’)-Ib-cr, sul1, dfrA1 and tetA. To the best of our knowledge, this is the first report of a bla_VIM-1 and mcr-9-coharbouring E. hormaechei isolate of food origin worldwide. The identification of a multidrug-resistant VIM-1 and mcr-9 positive Enterobacter hormaechei isolate from food is worrisome as retail meat and meat products could serve as a vehicle for these MDR bacteria, which could be transferred between animals and humans through the food chain. It further highlights that Enterobacterales co-producing MCR and carbapenemases being found in the food chain indeed correspond to a One-Health issue, highlighting the need for serious steps to prevent their further dissemination.

Clostridium perfringens is an often-harmful intestinal bacterium that causes various diseases ranging from food poisoning to life-threatening fulminant disease. Potential treatments include phage-derived endolysins, a promising family of alternative antimicrobial agents. We surveyed the genome of the C. perfringens st13 strain and identified an endolysin gene, psa, in the phage remnant region. Psa has an N-terminal catalytic domain that is homologous to the amidase_2 domain, and a C-terminal domain of unknown function. psa and gene derivatives encoding various Psa subdomains were cloned and expressed in Escherichia coli as N-terminal histidine-tagged proteins. Purified His-tagged full-length Psa protein (Psa-his) showed C. perfringens-specific lytic activity in turbidity reduction assays. In addition, we demonstrated that the uncharacterized C-terminal domain has cell wall-binding activity. Furthermore, cell wall-binding measurements showed that Psa binding was highly specific to C. perfringens. These results indicated that Psa is an amidase endolysin that specifically lyses C. perfringens; the enzyme’s specificity is highly dependent on the binding of the C-terminal domain. Moreover, Psa was shown to have a synergistic effect with another C. perfringens-specific endolysin, Psm, which is a muramidase that cleaves peptidoglycan at a site distinct from that targeted by Psa. The combination of Psa and Psm may be effective in the treatment and prevention of C. perfringens infections.

We developed two multiplex polymerase chain reactions (PCRs) for the detection of extended-spectrum β-lactamases (ESBLs), plasmid-mediated AmpC β-lactamases, aac(6′)-Ib gene, and integrase genes (intI1, intI2, and intI3) in class 1, 2, and 3 integrons in Gram-negative bacteria. We evaluated the PCRs using 109 Gram-negative isolates from non-organic (ANO) and organic (AO) vegetables and fruits. Screening of ANO substances identified five SHV, one TEM-1, one CTX-M, 20 AmpC-CS, and two intI1 positives. DNA sequencing revealed CTX-M in Pantoea spp. was bla_RANH-2, a plasmid-mediated CTX-M related ESBL gene only found in Rahnella spp. Of the 20 AmpC-CS positives, 10 were CMY/MIR/ACT/EC (3 new variants), eight were ACT, one was AZECL, and one was new Pseudomonas-related AmpC family. Screening of AO substances identified 11 SHV, two TEM-1, three CTX-M (one OXY-2, two CTX-M-14/-15), two OXA-9, 13 AmpC-CS and one intI1 positives. The 13 AmpC-CS positives were five CMY/MIR/ACT/EC, three ACT, one MOX-12 variant, and four ADC (one ADC-25 and three new variants). We developed a rapid, easy-to-perform, low-cost, and reliable multiplex PCR system for screening clinically relevant β-lactamases and integrons in Gram-negative bacteria. We showed the prevalence of ESBLs and AmpC β-lactamases among our panel of ampicillin-resistant Gram-negative strains and detection of NDM and OXA carbapenemases.