Transmissibility and Persistence of the Plasmid-Borne Mobile Colistin Resistance Gene, , Harbored in Poultry-Associated .

Colistin, a last-resort antibiotic, is used to treat infections caused by multi-drug-resistant Gram-negative bacteria. Colistin resistance can emerge by acquiring the mobile colistin gene, , usually plasmid borne. Studies on and its transmissibility are limited in the Middle East and North Africa (MENA) region. Here, we investigated the occurrence of in 18 previously collected isolates collected from chicken samples in Qatar; whole-genome sequencing was performed to determine the location (plasmid-borne and chromosomal) of in the isolates. Additionally, we assessed the transmissibility of plasmid-borne and its cost on fitness in biofilms. Our results showed that the isolates belonged to different sequence types, indicating that was occurring in strains with diverse genetic backgrounds. In silico analysis and transformation assays showed that all the isolates carried on plasmids that were mainly IncI2 types. All the plasmids were found to be transmissible by conjugation. In biofilms, a significant reduction in the number of CFU (≈0.055 logs CFU/mL) and colistin resistance (≈2.19 log CFU/mL) was observed; however, the reduction in resistance was significantly larger, indicating that the plasmids incur a high fitness cost. To our knowledge, this is the first study that investigates transmissibility and persistence in Qatar. Our findings highlight that has the potential to spread colistin resistance to potentially disparate strains and niches in Qatar, posing a risk that requires intervention.