| Abstract |
Colistin remains a high-priority, critically important antimicrobial that is used for treating severe infections caused by multidrug-resistant (MDR) Gram-negative bacteria. However, colistin resistance and the emergence of the mobile colistin resistance (mcr) genes have been increasingly documented in clinical and community settings, including in humans, animals, and the environment [[1], [2], [3]], which severely limits available antimicrobial options for addressing critical infections. Previous studies have reported that the wide dissemination of mcr-1 across Lebanon, an East Mediterranean country, is a major concern, especially in agricultural areas. Recently, we have identified a novel mcr variant, mcr-1.26, which appears to be spreading in Lebanon and is rarely reported abroad. This variant has been detected in hospitalised patients [4], otherwise healthy people [2], and birds [3,5] in Lebanon. Mcr-1.26–harbouring bacteria appear to concurrently exhibit resistance to other clinically and agriculturally important antimicrobials. Subsequently, we aimed to assess the faecal carriage and antimicrobial susceptibility patterns of colistin-resistant E. coli in backyard food animals in largely disenfranchised areas of North and South Lebanon.
Many individuals in Lebanese rural and agricultural areas own backyard food animals that constitute an important source of nutrition and income. This is vital for disenfranchised communities that face critical socioeconomic challenges and have limited resources that are further weakened by the ongoing economic crisis in Lebanon. The latter has resulted in a lack of government subsidies and restricted access to affordable veterinary supportive care [6]. This prevailing situation often compels individuals to resort to self-prescribing practices, driven by the need to reduce costs and cope with limited access to affordable veterinary services. Consequently, it is necessary to investigate the spread of resistance to colistin and other antimicrobials in these settings [6]. Thirty-three fresh faecal swab samples were collected from different animals from 16 farms in July 2022. The samples were homogenised and spread onto RAPID'E. coli 2 Medium (Bio-Rad, Hercules, CA, USA) plates supplemented with colistin (3.5 mg/L) (Supplementary data 1). After incubation for 24 hours at 37 °C under aerobic conditions, putatively colistin-resistant E. coli colonies were selected and purified. The identity of the isolates was further confirmed using MALDI-TOF VITEK MS (bioMérieux, Marcy L'Etoile, France). We successfully detected the presence of the MCR-1 protein in four colistin-resistant E. coli isolates using the NG-Test® MCR-1 (NG Biotech, Guipry, France) lateral flow immunoassay (LFA). These isolates were characterised by minimum inhibitory concentrations (MICs) of colistin that ranged between 4 and 8 mg/L. The isolates were also found to be resistant to more than three different antimicrobial classes, indicating that they were multi-drug resistant (MDR) (Table 1). Given that the mcr-1 is the most prevalent mobile colistin resistance determinant, the NG-Test® MCR-1 LFA provides a valuable diagnostic tool in Lebanon and other low- and middle-income countries. In these settings, the Kirby–Bauer disk diffusion method has been commonly used for testing colistin susceptibility, but it lacks precision in distinguishing susceptible from resistant isolates [7]. |
| Authors |
Dina Daaboul  , Issmat I. Kassem , Khaled El Omari , Nahla O. Eltai , Jouman Hassan , Hadi Al Jamal , Souad Fayad , Rayane Salma , Anahita Ghorbani Tajani  , Bledar Bisha , Monzer Hamzé , Saoussen Oueslati , Kevin J. Cummings , Fouad Dabboussi , Thierry Naas , Marwan Osman
|
