Colistin resistance in Escherichia coli and Klebsiella pneumoniae in humans and backyard animals in Ecuador

Abstract

Objective. Colistin is an antibiotic of last resort for treating serious Gram-negative bacterial infections. However, the misuse of colistin, especially as an animal growth promoter, has contributed to increasing antimicrobial resistance, mediated mainly through plasmid transfer of the mcr-1 gene. This study assessed the prevalence of phenotypic and molecular colistin resistance in Escherichia coli and Klebsiella pneumoniae in Ecuador in healthy humans and their chickens and pigs. Methods. Fecal samples were collected from humans and their chickens and pigs in two rural coastal and Amazon regions between April and August 2020. Gram-negative bacteria were isolated and identified using conventional techniques. Phenotypic resistance was determined using the broth microdilution technique, and the mcr-1 gene was detected using conventional polymerase chain reaction. Results. A total of 438 fecal samples were obtained from 137 humans, 147 pigs and 154 chickens. The prevalence of E. coli isolates was 86.3% (378/438) and K. pneumoniae, 37.4% (164/438). Overall, the mcr-1 gene was found in 90% (340/378) of E. coli isolates, with higher prevalences found in isolates from coastal regions (96.5%, 191/198), humans (95.6%, 111/116) and chickens (91.8%, 123/134); for K. pneumoniae, the gene was found in 19.5% (32/164) of isolates, with equal distribution between regions and hosts. Only four isolates, two E. coli and two K. pneumoniae, showed phenotypic resistance: mcr-1 was present in both E. coli strains but absent in the K. pneumoniae strains. Conclusions. Despite a low prevalence of phenotypic resistance to colistin, the high prevalence of the mcr-1 gene in E. coli is of concern. Ecuador’s ban on using colistin in animal husbandry must be enforced, and continual monitoring of the situation should be implemented.

Colistin resistance among the Gram-negative nosocomial pathogens in India: A systematic review and meta-analysis

“…This level of resistance is also significant, especially considering the widespread occurrence of E. coli and the potential for A. baumannii to cause severe hospital-acquired infections. In E. coli , the Col R levels are often very low as reported at 0.5% in Ecuador from faecal samples of humans, pigs, and chickens [25], although higher levels have been observed in Asian countries [31,32]. A recent meta-analysis reported the prevalence of Col R E. coli in food samples and food-producing animals to be 5.70% [33].…”

Co-Harboring of Beta-Lactamases and mcr-1 Genes in Escherichia coli and Klebsiella pneumoniae from Healthy Carriers and Backyard Animals in Rural Communities in Ecuador

“…As such, there is an urgent need for increased surveillance and epidemiological control to prevent the emergence of antibiotic resistance and implement timely intervention strategies. Low-income rural areas in Latin-American countries, where backyard animal husbandry is prevalent [74], are particularly vulnerable to the spread of antibiotic-resistant pathogens. Of special concern is the presence of several ST identified in this study that have been previously associated with epidemiologically relevant clones in the hospital and non-hospital environments, highlighting the need for further surveillance addressed to control the spread of MDR bacteria and underscores the need for a coordinated One-Health approach to combat the global threat of antibiotic resistance.…”

“…Despite the ban of colistin use in animal husbandry in Ecuador since 2019, the continuous use of other antibiotics, such as β-lactams in agricultural production, may contribute to the permanent co-harboring of these genes in animal and human carriers [74]. This, in turn, increases the risk of zoonotic transmission of resistant bacteria from animals to humans, given the close coexistence between humans and backyard animals.…”

“…The colistin-resistant isolates used in this study were obtained from a previously collected bacterial collection at Universidad de las Americas, originating from a study that aimed to investigate the prevalence of antibiotic-resistant bacteria in various hosts within two rural localities of Ecuador: La Reforma and Santo Domingo de los Tsáchilas (coastal region), and San José and Samasunchi, Pastaza (Amazon region) [74]. In total, 30 isolates of E. coli and 32 of K. pneumoniae that harbored both the mcr-1 gene and a minimum inhibitory concentration of ≥ 4µg/mL were selected for analysis (Supplementary Figure S1).…”

Risk factors associated with colistin resistance in carbapenemase-producing Enterobacterales: a multicenter study from a low-income country

“…In Ecuador, Ortega-Paredes et al reported the first clinical isolate of colistin-resistant Escherichia coli harboring mcr -1 in 2016 [ 12 ]. Since then, mcr -1 in E. coli and Klebsiella pneumoniae has been described in Ecuador in animals from rural farms [ 13 ]. Therefore, this study aimed to assess the epidemiology and risk factors associated with colistin-resistant carbapenemase-producing Enterobacterales (CR-CPE) and describe the mortality in a low-income country.…”