Circulation of multi-drug-resistant Shigella sonnei and Shigella flexneri among men who have sex with men in Barcelona, Spain, 2015-2019.

BACKGROUND: In high-income countries, shigellosis is mainly found in travellers to high-risk regions or in men who have sex with men (MSM). This study investigated the genomic characteristics and the features of antimicrobial resistance of MSM-associated Shigella flexneri and Shigella sonnei circulating in Barcelona, Spain, elucidating their connectivity with contemporaneous Shigella spp. from other countries. METHODS: Antimicrobial susceptibility, whole-genome sequencing, genomic characterization and phylogenetic analysis were performed in MSM-associated Shigella spp. recovered from 2015 to 2019. Reference genomes of MSM-associated Shigella spp. were included for contextualization and to determine their connection with international outbreaks. RESULTS: In total, 44 S. flexneri and 26 S. sonnei were identified among MSM. Overall, 80% showed resistance to azithromycin, 65.7% showed resistance to trimethoprim-sulphamethoxazole and 32.8% showed resistance to ciprofloxacin; 27.1% were resistant to all three antimicrobials. mphA and/or ermB, and qnrS and mutations in the quinolone resistance determining regions were found in the azithromycin- and ciprofloxacin-resistant isolates, respectively. Additionally, two isolates carried blaCTX-M-27. Single-nucleotide-polymorphism-based analysis revealed that the isolates were organized into different lineages, most of which were closely related to dominant MSM-associated lineages described previously in the UK and Australia. CONCLUSIONS: This study investigated the circulation of lineages of S. flexneri and S. sonnei among MSM in Spain that were mainly resistant to first-/second-line oral treatments, and closely related to dominant MSM-associated lineages described previously in the UK and Australia. These data reinforce the urgent need for the implementation of public health measures focusing on the early detection and prevention of transmission of this emerging pathogen, which is contributing to the antimicrobial resistance crisis in sexually transmitted infections.

Faecal phageome of healthy individuals: presence of antibiotic resistance genes and variations caused by ciprofloxacin treatment.

OBJECTIVES: Antimicrobial resistance genes (ARGs) can be transferred by means of mobile genetic elements, which play a critical role in the dissemination of resistance in the bacterial community. ARG transmission within mobile genetic elements has been reported in plasmids and transposons but less frequently in bacteriophages. Here, the bacteriophage fraction of seven human faecal samples was purified and deep-sequenced to detect the presence of ARGs in the phage particles. METHODS: Seven faecal samples (five from healthy individuals and two from a patient before and after receiving ciprofloxacin treatment) were used to extract phage DNA, which was purified and then sequenced in a MiSeq (Illumina). Generated reads were checked for quality and assembled, and then the generated contigs analysed with Kraken, PHASTER, VirSorter and Prokka. Some genes were also validated by quantitative PCR. RESULTS: Analysis of the purified phage DNA by Kraken identified from 4 to 266 viruses in the samples. The viral fraction corresponded mainly to the order Caudovirales, including phages from the Siphoviridae and Myoviridae families. Bacterial genes associated with antimicrobial resistance were detected in the viral DNA, as confirmed by quantitative PCR. Higher densities of ARG-carrying phage particles were observed in the post- versus pre-ciprofloxacin treatment sample. CONCLUSIONS: The finding of ARGs in phage particles supports the description of phages as mobile elements contributing to the dissemination of bacterial antibiotic resistance and suggests ciprofloxacin treatment may play a role in the release of ARG-carrying particles, thereby increasing resistance.