Polymyxin Resistant Bacteria in Australian Poultry

Abstract

Resistance to last-resort antibiotics is significant public health issue. Antibiotic use in animal husbandry may be a driver of resistance that can subsequently be disseminated via the food chain. This study sought to determine the level of polymyxin resistance in Gram-negative pathogens present in Australian poultry, particularly the presence of mobilizable mechanisms of polymyxin resistance. Cloacal swabs from 213 birds were taken in a point prevalence survey from six different farms at a Victorian chicken processing facility. Colistin resistant organisms were recovered by direct plating on CHROMagar COL-APSE media. Bacterial isolates were identified and analyzed by MALDI-TOF, biochemical and genotypic assays. The 213 specimens yielded 57 (26.8%) colistin-resistant Gram-negative organisms, all of which have been previously described as exhibiting intrinsic resistance to polymyxin antibiotics. The most frequent organism was identified as Hafnia paralvei (40/57; 70%). Other colistin-resistant organisms included Aeromonas hydrophila (16%), Myroides odoratus (7%), Alcaligenes faecalis (5%), and Pseudochrobactrum spp. (2%). No mobile colistin resistance (mcr) genes were detected, although the arnA gene was identified in two A. hydrophila isolates and may mediate colistin resistance in these isolates. Intrinsic polymyxin-resistant organisms are widely distributed in the food chain, with over a quarter of the birds tested yielding a polymyxin-resistant organism. However, strains containing mcr genes remain rare in Australian poultry.

Potential sources and characteristic occurrence of mobile colistin resistance (mcr) gene-harbouring bacteria recovered from the poultry sector: a literature synthesis specific to high-income countries

“…In Canada, COL is not approved for use in veterinary medicine. However, it has been cautiously used orally in managing intestinal diseases in livestock at one time in Canada (Rhouma et al, 2019), while COL (although not approved in the continent) is used in food animals at a minimal level in Australia (Ellem et al, 2017;Bean et al, 2020).…”

“…This highlights the need for adherence to basic infection prevention and control (IPC) practices such as hand hygiene by animal and meat handlers (slaughterhouse personnel) and food preparers and adequate cooking of food. Nevertheless, it is worthy to note that none of nine COL-resistant isolates from slaughtered chickens sampled (in 2016) in Australia harboured mcr-1 to mcr-5 (Bean et al, 2020). However, an arnA-like gene possibly conferred polymyxin resistance in the isolates.…”

Draft Genome Sequence of Hafnia paralvei Strain VBC_1714, Isolated from Frozen Cod Fillet Imported from Russia to Norway

“…Hafnia spp. are common gut bacteria that are generally considered nonpathogenic and are associated with cheese production and food spoilage ( 1 ). They are, however, infrequently reported as opportunistic pathogens causing infections in humans and animals and have been associated with a range of food products ( 2 , 3 ).…”

“…They are, however, infrequently reported as opportunistic pathogens causing infections in humans and animals and have been associated with a range of food products ( 2 , 3 ). Hafnia strains can carry multiple antimicrobial resistance and virulence genes ( 1 , 4 – 6 ) and are therefore highly interesting from a human health perspective.…”

“…Strain VBC_1714 contained one CRISPR array with five spacers and the arnA gene, which has been linked to polymyxin resistance ( 1 ). The class C β-lactamase gene bla ACC-1b , which confers resistance to aminopenicillins and narrow-spectrum cephalosporins ( 4 ), was identified using AMRFinder v3.1.1b ( 17 ).…”