Colistin has become the last-line antimicrobial for the treatment of multidrug resistant (MDR) Enterobacterales in human medicine. To date, several colistin resistance genes have been described. Of them mcr-1 is disseminated worldwide in Escherichia coli of human and animal origin. The aim of this study was to characterize mcr-mediated resistance plasmids from E. coli of animal origin in Spain. From our strain collection, 70 E. coli of pig origin collected between 2005 and 2014 (10 per year, except for years 2009-2010-2013) were randomly selected and screened for the presence of mcr-genes. Additionally, 20 E. coli isolated in 2011 from white storks (Ciconia ciconia) from the same urban household waste landfill associated colony were also included. Whole genome sequencing of mcr-positive isolates was carried out on a MiSeq (Illumina). Hybrid whole genome sequencing strategy combining nanopore and Illumina technologies were performed in a selection of isolates to close the genomes and plasmids and identify the presence of antimicrobial resistance genes. Minimum inhibitory concentration (MIC) was used to assess the susceptibility to colistin. Mating experiments were carried out to evaluate transferability of the mcr-genes. A total of 19 mcr-1 and one mcr-4 positive isolates were detected, 15 from pigs distributed during the study period, and five from storks collected in 2011. No other mcr-variants were found. The MICs for colistin ranged between 4 and >4 mg/L. High diversity of STs were detected among the mcr-1 positive E. coli isolates, with only ST-10 shared between pigs and white storks. Except for one isolate, all were genotypic and phenotypically MDR, and five of them also harbored cephalosporin resistance genes (bla CTX−M−14 , bla SHV−12 , and three bla CMY−2). mcr-1 genes were mobilizable by conjugation, associated with IncX4, IncHI2, and IncI2 plasmids. In our study, mcr-1 genes have been circulating in pig farms since 2005 harbored by a variety of E. coli clones. Its persistence may be driven by co-selection since plasmids containing mcr-1 also exhibit resistance to

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Sexually transmitted infections (STIs) by Mycoplasma genitalium are a major problem worldwide, especially given their marked and rapid propensity for developing antimicrobial resistance. Since very few treatment options exist, clinicians face an important challenge in the management of the infection. In this scenario, little is known regarding the transmission dynamics of M. genitalium and the epidemiology of antimicrobial resistance. This mgpB-based molecular typing study, conducted among 54 asymptomatically infected individuals prospectively recruited from an STI screening service, reveals two distinct epidemiological clusters that significantly correlate with sexual conduct in heterosexuals and men who have sex with men (MSM), respectively. This well-defined structuration suggests the presence of two independent sexual networks with little connectivity between them. On the other hand, the study demonstrates the multiclonal feature of the emergence of antibiotic resistance in M. genitalium to both macrolides and fluoroquinolones. The high prevalence of macrolide resistance in M. genitalium among MSM, influenced by dense network connectivity and strong antibiotic selective pressure, may correspond to allodemics affecting other STIs such as gonorrhea, syphilis and enteric pathogens. Collaterally, the structural and functional impact of mutations in the mgpB gene, encoding the major adhesin P140 (MgpB), may require further investigation.

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Background Neisseria gonorrhoeae (NG) isolates with high-level azithromycin resistance (HL-AziR) have emerged worldwide in recent decades, threatening the sustainability of current dual-antimicrobial therapy. Objectives This study aimed to characterize the first 16 NG isolates with HL-AziR in Barcelona between 2016 and 2018. Methods WGS was used to identify the mechanisms of antimicrobial resistance, to establish the MLST ST, NG multiantigen sequence typing (NG-MAST) ST and NG sequence typing for antimicrobial resistance (NG-STAR) ST and to identify the clonal relatedness of the isolates with other closely related NG previously described in other countries based on a whole-genome SNP analysis approach. The sociodemographic characteristics of the patients included in the study were collected by comprehensive review of their medical records. Results Twelve out of 16 HL-AziR isolates belonged to the MLST ST7823/NG-MAST ST5309 genotype and 4 to MLST ST9363/NG-MAST ST3935. All presented the A2059G mutation in all four alleles of the 23S rRNA gene. MLST ST7823/NG-MAST ST5309 isolates were only identified in men who have sex with women and MLST ST9363/NG-MAST ST3935 were found in MSM. Phylogenomic analysis revealed the presence of three transmission clusters of three different NG strains independently associated with sexual behaviour. Conclusions Our findings support the first appearance of three mild outbreaks of NG with HL-AziR in Spain. These results highlight the continuous capacity of NG to develop antimicrobial resistance and spread among sexual networks. The enhanced resolution of WGS provides valuable information for outbreak investigation, complementing the implementation of public health measures focused on the prevention and dissemination of MDR NG.