China antimicrobial resistance surveillance network for pets(CARPet),2018 to 2021

China Antimicrobial Resistance Surveillance Network for Pets(CARPet)was established in 2021 to monitor the resist-ance profiles of clinical bacterial pathogens from companion animals.From 2018 to 2021,we recovered and tested 4,541 isolates from dogs and cats across 25 Chinese provinces,with Escherichia coli(18.5%)and Staphylococcus pseudintermedius(17.8%)being the most predominant bacterial species.The Enterobacterales were highly susceptible to tigecycline,meropenem,colistin,and amikacin(70.3%-100.0%),but showed moderate resistance to ampicillin,ceftriaxone,doxycycline,florfenicol,levofloxacin,enrofloxacin,and trimethoprim-sulfamethoxazole(29.3%-56.7%).About 66.3%of Acinetobacter spp.were resistant to florfenicol,with relatively low resistance to another 11 antibiot-ics(1.2%-23.3%).The Pseudomonas spp.showed high susceptibility to colistin(91.7%)and meropenem(88.3%).The coagulase-positive Staphylococcus spp.showed higher resistance rates to most antimicrobial agents than coagulase-negative Staphylococcus isolates.However,over 90.0%of Staphylococcus spp.were susceptible to linezolid,dapto-mycin and rifampin,and no vancomycin-resistant isolates were detected.E.faecium isolates demonstrated higher resistance rates to most antimicrobial agents than E.faecalis isolates.Streptococcus spp.isolates showed low resistance to most antimicrobial agents except for doxycycline(78.2%)and azithromycin(68.8%).Overall,the tested clinical isolates showed high rates of resistance to commonly used antimicrobial agents in companion animals.Therefore,it is crucial to strengthen the monitoring of bacterial resistance in pets.By timely and effectively collecting,analyzing,and reporting antimicrobial resistance dynamics in pets,the CARPet network will become a powerful platform to provide scientific guidance for both pet medical care and public health.

Antimicrobial susceptibility testing in veterinary medicine:performance,interpretation of results,best practices and pitfalls

The performance of antimicrobial susceptibility testing(AST)of bacteria and the interpretation of AST results for bacteria isolated from animals are complex tasks which must be performed using standard published methodology and overseen by experts in clinical microbiology and in consultation with clinical pharmacologists.Otherwise,AST has significant potential for errors and mistakes.In this review,we provide guidance on how to correctly perform AST of bacteria isolated from animals and interpret the AST results.Particular emphasis is placed on the various approved or published methodologies for the different bacteria as well as the application of interpretive criteria,including clinical breakpoints and epidemiological cut-off values(ECVs/ECOFFs).Application of approved interpretive criteria and definitions of susceptible,susceptible dose-dependent,nonsusceptible,intermediate,and resistant for clinical breakpoints as well as wild-type and non-wildtype for ECVs,are explained and the difficulties resulting from the lack of approved clinical breakpoints for other bacteria,indications,and animal species is discussed.The requirement of quality controls in any AST approach is also emphasized.In addition,important parameters,often used in monitoring and surveillance studies,such as MIC50,MIC90,and testing range,are explained and criteria for the classification of bacteria as multidrug-resistant,extensively drug-resistant or pandrug-resistant are provided.Common mistakes are presented and the means to avoid them are described.To provide the most accurate AST,one must strictly adhere to approved standards or validated methodologies,like those of the Clinical and Laboratory Standards Institute or other internationally accepted AST documents and the detailed information provided therein.

Low prevalence of colistin-resistant Escherichia coli from companion animals,China,2018-2021

China banned colistin as growth promoter for animals in the year of 2017.A decrease of colistin-resistant Escherichia coli(COREC)and mcr-1-positive Escherichia coli(MCRPEC)were observed in livestock(pigs and chickens)and humans after the ban policy.However,the prevalence of COREC among Chinese companion animals after the ban policy has not been investigated.Here,we recovered 771 E.coli isolates from the China Antimicrobial Resistance Surveil-lance Network for Pets(CARPet)surveillance system(19 provinces/municipalities)from 2018 to 2021.We identified 12 COREC from eight dogs and four cats,among which one feline and three canine isolates were MCRPEC.The prevalence of COREC and MCRPEC in pets from 2018-2021(1.1%-2.2%and 0.8%-1.1%)were lower than those from 2012-2016(7.1%-17.8%and 6.1%-14.3%).The phylogenetic analysis revealed that the four MCRPEC isolates displayed genetic diversity,while one canine isolate exhibited only 26 SNPs difference with one human MCRPEC isolate in the same city,suggesting the exchange of MCRPEC isolates between companion animals and humans.In three MCRPEC isolates,mcr-1 was located on an IncI2 plasmid,which exhibited 99.5%-99.9%nucleotide sequence identity with plasmid pHNSD133-MCR from E.coli of chicken origin.In the remaining MCRPEC,mcr-1 was chromosomally located flanked by intact ISApl1 elements forming a unit of ISApl1-mcr-1-pap2-ISApl1.Despite the low prevalence of COREC and MCRPEC observed in companion animals after the ban policy,the association of pet-derived MCRPEC and mcr-carrying plasmids with those from humans and farm animals suggest that annual surveillance of colistin resistance in bacteria of pet origin is essential.