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3.2 Antimicrobial Resistance
The first revolutionary breakthrough in the field of medicine dated back to discovery
of penicillin by Sir Alexander Fleming in 1928, which marked the beginning of
golden era of antibiotics. The antibiotics revolutionized the field of medicine by
mitigating the burden of infectious diseases globally. Unfortunately, this era lasted
for few decades as bacteria developed resistance to these antibiotics and due to lack
of discovery of new antibiotics (Lewis 2020). Antimicrobial resistance is defined as
the development of resistance against the antimicrobial drugs used to inhibit or kill
the bacterial growth. Excessive and misuse of antimicrobials in humans as well as
in animals has been shown to accelerate the selection and emergence of resistant
microorganisms to multiple antimicrobials. Infections caused by multi drug resistant bacteria are increasingly common and represent a serious problem to public
health all over the world (Holmes et al. 2016). These multidrug resistant bacteria are
called superbugs and the World Health Organization has warned of reversing back
to “post-antibiotic era”, which will result in frequent untreatable infections and
small injuries or surgical procedures can be fatal (Nathan and Cars 2014; Holmes
et al. 2016).
The looming threat of antimicrobial resistance is no longer a new phenomenon.
Sir Alexander Fleming also predicted the probability of antimicrobial resistance
emergence at the time of receiving his Noble Price in 1945 (Day and Read 2016).
The increased use of antibiotics means the stronger and longer exposure of antibiotics to the bacteria, which in turn, impose selective pressure on microbial communities to sustain their population (Fig. 3.2). The antibiotic consumption is one of the
key factors which contribute towards development of resistance among bacteria due
to selective pressure (Baym et al. 2016; Pouwels et al. 2018). The hidden problem
of antibiotic selective pressure is that commensal bacterial species are unnecessarily
being exposed to antibiotics which promote resistance even in non-pathogenic/commensal bacteria. Moreover, inter-species and intra-species exchange of genetic
transmission further leads to serious and harder to treat infectious diseases (Naylor
et al. 2018). Horizontal gene transfer mechanisms are regarded as one of the most
common mechanisms of antibiotic genes transfer, in addition to the vertical gene
transfer. Antibiotic selective pressure can select for chromosomal mutations conferring resistance to antibiotic, which can be transferred vertically to subsequent
microbial generations. Alternatively, many genes responsible for drug resistance are
found on plasmids or on transposons that can be transferred across inter-species and
intra-species through horizontal gene transfer (Holmes et al. 2016; O’Neill 2016b).
However, this is important to acknowledge that beside antimicrobial over use, other
natural and environmental elements do exist; such as climate change is also silently
driving a shift in the emergence of antibiotic resistance (Wellington et al. 2013). For
instance, recent study showed increased rate of antibiotic resistance with the increasing local temperature in the USA. An increasing percentage of antibiotic resistance
was found in three common pathogens Escherichia coli (4.2%), Klebsiella pneumoniae (2.2%) and Staphylococcus aureus (2.7%). Furthermore, this increase in
M. Mohsin et al.
3.2 Antimicrobial Resistance
The first revolutionary breakthrough in the field of medicine dated back to discovery
of penicillin by Sir Alexander Fleming in 1928, which marked the beginning of
golden era of antibiotics. The antibiotics revolutionized the field of medicine by
mitigating the burden of infectious diseases globally. Unfortunately, this era lasted
for few decades as bacteria developed resistance to these antibiotics and due to lack
of discovery of new antibiotics (Lewis 2020). Antimicrobial resistance is defined as
the development of resistance against the antimicrobial drugs used to inhibit or kill
the bacterial growth. Excessive and misuse of antimicrobials in humans as well as
in animals has been shown to accelerate the selection and emergence of resistant
microorganisms to multiple antimicrobials. Infections caused by multi drug resistant bacteria are increasingly common and represent a serious problem to public
health all over the world (Holmes et al. 2016). These multidrug resistant bacteria are
called superbugs and the World Health Organization has warned of reversing back
to “post-antibiotic era”, which will result in frequent untreatable infections and
small injuries or surgical procedures can be fatal (Nathan and Cars 2014; Holmes
et al. 2016).
The looming threat of antimicrobial resistance is no longer a new phenomenon.
Sir Alexander Fleming also predicted the probability of antimicrobial resistance
emergence at the time of receiving his Noble Price in 1945 (Day and Read 2016).
The increased use of antibiotics means the stronger and longer exposure of antibiotics to the bacteria, which in turn, impose selective pressure on microbial communities to sustain their population (Fig. 3.2). The antibiotic consumption is one of the
key factors which contribute towards development of resistance among bacteria due
to selective pressure (Baym et al. 2016; Pouwels et al. 2018). The hidden problem
of antibiotic selective pressure is that commensal bacterial species are unnecessarily
being exposed to antibiotics which promote resistance even in non-pathogenic/commensal bacteria. Moreover, inter-species and intra-species exchange of genetic
transmission further leads to serious and harder to treat infectious diseases (Naylor
et al. 2018). Horizontal gene transfer mechanisms are regarded as one of the most
common mechanisms of antibiotic genes transfer, in addition to the vertical gene
transfer. Antibiotic selective pressure can select for chromosomal mutations conferring resistance to antibiotic, which can be transferred vertically to subsequent
microbial generations. Alternatively, many genes responsible for drug resistance are
found on plasmids or on transposons that can be transferred across inter-species and
intra-species through horizontal gene transfer (Holmes et al. 2016; O’Neill 2016b).
However, this is important to acknowledge that beside antimicrobial over use, other
natural and environmental elements do exist; such as climate change is also silently
driving a shift in the emergence of antibiotic resistance (Wellington et al. 2013). For
instance, recent study showed increased rate of antibiotic resistance with the increasing local temperature in the USA. An increasing percentage of antibiotic resistance
was found in three common pathogens Escherichia coli (4.2%), Klebsiella pneumoniae (2.2%) and Staphylococcus aureus (2.7%). Furthermore, this increase in
M. Mohsin et al.