**Abstract**

The drug abuse known to occur during growth of animals intended for food production, because of their use as either a prophylactic or therapeutic treatment, promotes the emergence of bacterial drug resistance. It has been reported that at least 25% of the foodborne isolates show drug resistance to one or more classes of antimicrobials (FAO 2018). There are diverse mechanisms that promote drug resistance. It is known that the use of sub-therapeutic doses of antibiotics in animals intended for food production promotes mutations of some chromosomal genes such as *gyrA-parC* and *mphA*, which are responsible for quinolone and azithromycin resistance, respectively. Also, the horizontal transfer of resistance genes as groups ("cassettes") or plasmids makes the spread of resistance to different bacterial genera possible, among which there could be pathogens. The World Health Organization considers the emergence of multidrug-resistant pathogenic bacteria as a health problem, since the illnesses caused by them complicate the treatment and increase the morbidity and mortality rates. The complication in the illness treatment caused by a multidrug-resistant pathogen causes economic losses to patients for the payment of long stays in hospitals and also causes economic losses to companies due to the absenteeism of their workers.

**Keywords:** multidrug-resistant bacteria, MDR, foodborne pathogens, antimicrobial resistance, MDR bacteria human health, MDR microorganism economic impact

#### **1. Introduction**

Increasing antimicrobial resistance (AMR) is a global public health threat. The excessive use and abuse of drug therapies in humans and in the animals intended for human consumption, and its bad disposition as a waste, have tightened up the problem in recent years [1]. This phenomenon affects any person regardless of sex, age, origin, or social status and threats the ability to effectively solve the treatments of different diseases and also compromises the food security, economy, and development of the countries [2].

Microorganisms are sensitive to antimicrobials when they do not harbor components involved in degrading them. AMR occurs when bacteria, fungi, viruses, and parasites are exposed for a long time to sub-therapeutic doses of drugs such as antibiotics, antifungals, antivirals, antimalarials, or anthelmintics that modify the ecology of microorganism. In order to contend with the residues present in their environment, microorganisms may acquire genetic elements that allow them to cope with these compounds and survive. In some cases, the use of poor quality drug, counterfeit products, incorrect product, and modified dosage can accelerate the development of microbial resistance. Another relevant factor for development of AMR is the inadequate disposal of waste generated in the agricultural production and pharmaceutical and wastewater treatment plants as they can be spread through the environment [3]. One of the recently described phenomena observed is the association between the emergence of multiresistant microorganisms (MMR) and the increase in the isolates that show the production of extended-spectrum betalactamase enzymes (ESBL). Currently, more than 200 varieties of BLEE enzymes are recognized with different substrates, and the frequency of isolates producing these enzymes varies from country to country (from 20 to 48%) [3].

Although there are many factors that favor the spread of antibiotic resistance, it affects different sectors, such as human health, animal health, agriculture, environment, and commercial trade [4]. It is estimated that 700,000 people die each year from infections caused by microorganisms resistant to antimicrobials and a large number of sick animals that do not respond to treatments [5]. Within the agricultural and food industry, resistant microorganisms represent a risk for production that threatens the global economy. For this reason, it is important to implement supervised agricultural regulations and practices that ensure the responsible use of antimicrobials in the production of animals and crops.
