12
1.2.4 Antimicrobial Resistance and Soil
Soil is a central hub and serves as source/sink for material exchange between animals, plants, air, rocks, water, etc. and was identified as a huge reservoir for antibiotic resistance genes originating from fungi, plants, bacteria and other organisms
(Figs. 1.1 and 1.2) (Monier et al. 2011). Many previously unknown antibiotic resistance genes from metagenomic studies on uncultured bacteria from soil has been
reported and numerous are yet to be explored (Riesenfeld et al. 2004). Although the
vegetables grown in unsupplemented soils are reported to harbor antibiotic resistance genes and thus antibiotic resistant microbes are naturally present in soils. This
can be understood by the fact that most of the antibiotics are being produced by
fungi or bacteria. Thus, these species also carries the genes providing resistance
against the antibiotics produced by them (Allen et al. 2010). However, but, the load
of antibiotic resistant microbes in manure supplemented soil is usually higher and
largely dependent on the class of antibiotics being used in the animal farms from
where the manure has been sourced (Marti et al. 2013).
Many studies have shown that vegetables pick up the antibiotics contained in the
manure/soil and many a times also during transport and distribution processes,
thereby exposing humans to hazards of transmission of antimicrobial resistance
(Beuchat 2002). It can also be influenced by the waste water being used for irrigation, contaminated harvesting equipments, the absorbing capacity of the soil, soil
microbiome and the antibiotic resistance genes and mobile genetic elements interacting between microbes in the soil (Chee-Sanford et al. 2009; Oluyege et al. 2015).
A group of researchers found high levels of tetracycline in manure and soil samples
from commercial swine farms in China. They also reported the presence of about
149 unique antibiotic resistance genes and up to 43% abundance of aphA (antibiotic
resistance gene against aminoglycoside antibiotic) in those samples (Zhu et al.
2013). Another group reported the presence of bla CTX-M gene (antibiotic resistance
gene against cefotaxime) as the most abundant antibiotic resistance gene providing
multiple drug resistance in the isolates from the swine farm and nearby soil samples. A study shows that many paddy fields in China have been polluted (presumably through animal waste based manures or otherwise) with numerous antibiotic
resistance genes showing more than 38% multiple drug resistance (Xiao et al. 2016).
1.2.5 Antimicrobial Resistance and Water Bodies
Being actively involved in day-to-day activities of almost all life forms, there is
heavy dependence of life on aquatic bodies and it is frequently the final endpoint for
most life activities and nutrient cycles. Quite naturally, the aquatic bodies serve as
natural sinks, hotspots and reservoirs for the antibiotics, antibiotic resistant bacteria,
and antibiotic resistance genes. These water bodies could be marine or fresh water
and constitute sea water, tap water, drinking water, ground water and waste water.
K. S. Singh et al.
1.2.4 Antimicrobial Resistance and Soil
Soil is a central hub and serves as source/sink for material exchange between animals, plants, air, rocks, water, etc. and was identified as a huge reservoir for antibiotic resistance genes originating from fungi, plants, bacteria and other organisms
(Figs. 1.1 and 1.2) (Monier et al. 2011). Many previously unknown antibiotic resistance genes from metagenomic studies on uncultured bacteria from soil has been
reported and numerous are yet to be explored (Riesenfeld et al. 2004). Although the
vegetables grown in unsupplemented soils are reported to harbor antibiotic resistance genes and thus antibiotic resistant microbes are naturally present in soils. This
can be understood by the fact that most of the antibiotics are being produced by
fungi or bacteria. Thus, these species also carries the genes providing resistance
against the antibiotics produced by them (Allen et al. 2010). However, but, the load
of antibiotic resistant microbes in manure supplemented soil is usually higher and
largely dependent on the class of antibiotics being used in the animal farms from
where the manure has been sourced (Marti et al. 2013).
Many studies have shown that vegetables pick up the antibiotics contained in the
manure/soil and many a times also during transport and distribution processes,
thereby exposing humans to hazards of transmission of antimicrobial resistance
(Beuchat 2002). It can also be influenced by the waste water being used for irrigation, contaminated harvesting equipments, the absorbing capacity of the soil, soil
microbiome and the antibiotic resistance genes and mobile genetic elements interacting between microbes in the soil (Chee-Sanford et al. 2009; Oluyege et al. 2015).
A group of researchers found high levels of tetracycline in manure and soil samples
from commercial swine farms in China. They also reported the presence of about
149 unique antibiotic resistance genes and up to 43% abundance of aphA (antibiotic
resistance gene against aminoglycoside antibiotic) in those samples (Zhu et al.
2013). Another group reported the presence of bla CTX-M gene (antibiotic resistance
gene against cefotaxime) as the most abundant antibiotic resistance gene providing
multiple drug resistance in the isolates from the swine farm and nearby soil samples. A study shows that many paddy fields in China have been polluted (presumably through animal waste based manures or otherwise) with numerous antibiotic
resistance genes showing more than 38% multiple drug resistance (Xiao et al. 2016).
1.2.5 Antimicrobial Resistance and Water Bodies
Being actively involved in day-to-day activities of almost all life forms, there is
heavy dependence of life on aquatic bodies and it is frequently the final endpoint for
most life activities and nutrient cycles. Quite naturally, the aquatic bodies serve as
natural sinks, hotspots and reservoirs for the antibiotics, antibiotic resistant bacteria,
and antibiotic resistance genes. These water bodies could be marine or fresh water
and constitute sea water, tap water, drinking water, ground water and waste water.
K. S. Singh et al.