**3. Antimicrobial resistance (AMR)**

A microbe is known as human's best friend but at the same time is his worst enemy. Antibiotics are known as magic bullets because of its magic in the previous era [48]. Antimicrobial resistance (AMR) can be defined as "the ability of any microbe to become resistant to available antimicrobial therapy to which it was previously found susceptible" [49]. AMR is a problem prevailing worldwide in both veterinary medicine and human sector where antibiotics are used mainly for treating diseases and animal growth promotion [50]. AMR is complex and multifactorial process and is the result of antimicrobial usage (AMU) in animal, human and agriculture sector. The rapid dissemination and spread of resistant bacteria and their associated genes are responsible for increased mortality and morbidity in animals, reduced production and diminished food security [48]. The overuse and misuse of antimicrobial agents has resulted in the appearance of resistance, threatening the prevention and treatment regimens [51]. Antibiotics are also added as food supplements in animal feed which also give rise to resistant bacteria. The usage of many of the growth supplements have been banned in most of the countries especially colistin, because it is the last resort antibiotic and it is also a resurgent drug therefore it can pose great risk of AMR [52]. The WHO (World Health Organization) identified potential antimicrobial resistant agent to which urgent antibiotics are needed [53]. Among the top priority pathogen; extended spectrum beta-lactamase (ESBLs producing *Escherichia coli*) have been recognized as emerging universal dilemma due to their increasing occurrence in livestock sector [54].

Among food-producing animals, cattle are the important reservoir of bacteria capable of producing ESBLs [55]. ESBLs are beta-lactamases that have the ability to degrade ceftazidime, ceftriaxone, cefotaxime, cefepime and monobactam antibiotics. The important variants of ESBLs are TEM, SHV, OXA and CTX-M. Of these variants, TEM and SHV were initially identified in *E. coli* and *Klebsiella pneumoniae*. *Pseudomonas* specie carries TEM, SHV and CTX-M. It is implicated that CTX-M has


### **Table 1.**

*Procedures and their details for combating antimicrobial resistance [57].*

*Introductory Chapter: Understanding Bovine Science - An Emerging and Re-emerging Menace… DOI: http://dx.doi.org/10.5772/intechopen.100603*

been originated from the *Kluyvera* specie persisting in the environment. Most of the bacteria carry the ESBLs on their plasmid facilitating horizontal gene transfer while CTX-M is encoded on bacterial chromosome [56].

AMR is a challenging problem and tackling it is hard however, advances in the field of biotechnology and nano-technology have resulted in procedures which not only target resistant genes but can also be used for treating microbe associated diseases in animals [57]. Many of these procedures are described in **Table 1** given below:
