Outbreak of highly pathogenic avian influenza A(H5N1) clade 2.3.4.4b virus in cats, Poland, June to July 2023

BackgroundOver a 3-week period in late June/early July 2023, Poland experienced an outbreak caused by highly pathogenic avian influenza (HPAI) A(H5N1) virus in cats.AimThis study aimed to characterise the identified virus and investigate possible sources of infection.MethodsWe performed next generation sequencing and phylogenetic analysis of detected viruses in cats.ResultsWe sampled 46 cats, and 25 tested positive for avian influenza virus. The identified viruses belong to clade 2.3.4.4b, genotype CH (H5N1 A/Eurasian wigeon/Netherlands/3/2022-like). In Poland, this genotype was responsible for several poultry outbreaks between December 2022 and January 2023 and has been identified only sporadically since February 2023. Viruses from cats were very similar to each other, indicating one common source of infection. In addition, the most closely related virus was detected in a dead white stork in early June. Influenza A(H5N1) viruses from cats possessed two amino acid substitutions in the PB2 protein (526R and 627K) which are two molecular markers of virus adaptation in mammals. The virus detected in the white stork presented one of those mutations (627K), which suggests that the virus that had spilled over to cats was already partially adapted to mammalian species.ConclusionThe scale of HPAI H5N1 virus infection in cats in Poland is worrying. One of the possible sources seems to be poultry meat, but to date no such meat has been identified with certainty. Surveillance should be stepped up on poultry, but also on certain species of farmed mammals kept close to infected poultry farms.

The first description of the complete genome sequence of multidrug-resistant Salmonella enterica serovar monophasic Typhimurium (1,4,[5],12:i:-) isolate with the mcr-1.1 gene on IncHI2 found in pig in Poland

Monophasic Salmonella Typhimurium (1,4,[5],12:i:-) is one of the leading Salmonella serovars causing human salmonellosis in Europe. It has been observed in Poland since 2008. This serovar is considered the one with the highest rate of mcr prevalence. This report presents a sequence characteristic of the multidrug-resistant (MDR) monophasic S. Typhimurium isolated from a pig faecal sample with the confirmed presence of the mcr-1.1 gene. The genome was assembled into the complete chromosome and 4 plasmids: IncHI2 (232 119 bp), IncFIB/IncFIC (133 901 bp), ColRNAI (6659 bp), and Col8282 (4066bp). The strain identified as ST34 carried multiple antimicrobial resistance genes located both on chromosome (tet(B)) and plasmids: mcr-1.1 and blaTEM-1B on ST4-IncHI2, and mef(B), blaTEM-1B, aadA1, qacL, dfrA12, aadA2, cmlA1, sul3, tet(M) on IncFIB/FIC. The mcr-1.1 gene was previously identified in E. coli deriving mainly from poultry, but this is the first case of the occurrence of mcr-positive Salmonella in Poland. The obtained results of analysis of the genome content draw attention to the problem of multidrug-resistant pathogens, especially in the context of resistance to colistin which is a last-resort antimicrobial.