Anti-Microbial Resistance (AMR) origin, development
and dissemination, How to avoid encountering
Totally Resistant to Treatment of Microbial Infection
Anti-microbial resistance (AMR) is the ability of microorganisms such as bacteria, fungi, viruses, and parasites to survive and grow in the presence of drugs that are meant to kill or inhibit them. AMR can originate from different sources, such as mutations in the microorganisms’ own genes, or the acquisition of resistance genes from other microorganisms through horizontal gene transfer (HGT). HGT is the movement of genetic material between different organisms without sexual reproduction. HGT can be mediated by mobile genetic elements (MGEs) such as plasmids, transposons, and integrons12. MGEs can capture resistance genes from chromosomes and transfer them to other bacteria via plasmids or phages23. Some resistance genes have been traced back to antimicrobial-producing organisms, such as the erm genes that confer resistance to macrolides3. AMR can develop and spread locally and globally through various routes, such as human and animal waste, food production and consumption, travel and trade, and environmental contamination34. AMR poses a serious threat to public health and animal welfare, as it reduces the effectiveness of available treatments and increases the risk of infections and mortality.
The public and farming Community and entrepreneurs
should be made aware of how Microbial Resistance - originates, develop, and
disseminate to avoid Human Body encountering Totally Resistant Treatment of
Microbial Infections
The field of Global
Medicine and Health Affairs recently encountered a worsening experience and
emanated a grief concern for the future of Antibiotic Medication - as a treatment
for Bacterial Infections of any type - especially of non-contagious diseases
(only for the time being) - such as wounds of any origin. The bad experience is
that in a hospital in the United States, a patient was found with a Bacterial
Infection, that is resistant to all the modern-day antibiotics and
antibacterial - and hence heavily depended on wound irrigation of stronger and
yet milder disinfectants acceptable to the body tissues exposed in the wound – A
practice holds resemblance to the era before the inventing the antibiotic for
the therapy and medications a many centuries older practice at the inception
history of humanitarian medical care and attention.
The concern emanated
here is not the treatment of the wound infected with Bacteria that is totally
resistant to all the available antibiotics, but if such bacteria becomes an internal pathogen (causing the disease within the body) – or rather an internal
pathogen attains the resistant to all known antibiotics - then it is
troublesome, and if not the appropriate antibiotic is found in time, will lead to
disastrous consequences not just only for individual cases - it will become
total mayhem of the entire medical care system, including the veterinary field because the Bacterial Resistance can spread rapidly Bacteria to Bacteria in no
time and a resistant bacteria can be contracted by a normal individual
introducing it a fresh nonresistant colony of commensals and saprophytes of that animal/individual.
Already present-day practitioners of all respects are having enough trouble
with Resistant Bacterial infections for antibiotics and anti-bacterial, and
bacteria developing resistance during the cause of treatment - particularly
after selecting an antibiotic as suitable, through Antibiotic Sensitive Test
(ABST).
The Origin of
Antibiotic and Anti-Microbial Resistance by Microbes
A few decades ago,
there were no proper regulatory mechanisms or authority on the use of antibiotics,
even in the countries invented, involved in mass-scale production of these
drugs - at that time; even on deriving newer and newer antibiotics and whenever
producing its analogue synthetically= (Antibacterial) is
celebrated as of a breakthrough for future course, not realizing what is stored
in by the targeted Microorganisms for the new antibiotic. A monster of
propaganda by the promoters of research – a monstrous act not knowing the
resistance developing before the promotion – but it is in fact a constraint in
the industry of antibiotics produced from another live microbe or fungi.
The most important thing we all must remember is, no antibiotic can arrest or kill
all the bacteria that cause diseases (pathogens) = each antibiotic can act only
against a certain group of pathogens, for example, the earliest antibiotic
Penicillin – and its modern-day analogues can act only, if these drugs
penetrate the cell wall of the bacteria, and it is most effective only at the
multiplication stages of bacterial infection. If a bacteria can shunt the
penetration of the antibiotic into its wall or inside of its cytoplasm – that
is called natural resistance, and if the microstructure of the bacteria
prevents the antibiotic from acting against these organisms – it is called
natural inert resistance, and the researchers do work only on these aspects –
to produce an improvised antibiotic or similar analog antibacterial, never
they can study about the acquiring resistance before at least
partially release it to the field of practice, despite the fact such action
itself responsible for spread of fresh mode of AMR.
What
we are discussing here is only about Acquiring Resistance of Microbes against
Antibiotics, as it is more threatening and difficult to handle during treatments.
Why do Microbes
Acquire resistance? It is simply surviving mechanism for Microbes, as for any
other living organism, whatever material or element, microbes realize as
harmful to their survival – they will try to neutralize it in the most effective
way and spread it from the bacterium to the bacterium in a same rapid manner. Eradication of disease-causing Pathogens
shall not kill the commensals and benefitting organisms, within the body such
an eradication would signal the onset of deficiency of certain vitamins,
leading to another disease condition.
Until the late 1980s in Sri Lanka, the ordinary groceries located near the extensive
cultivation areas stored Tetracycline capsules as part of their sale grocery –
and the farmers returning home would ask for “Gaha Karal” or “Laksha-Paha Karal”
in Sinhala or in Tamil “Iyanthu Ladcham kulusai” and the boutique owner will
dispense one or two Tetracycline capsules, as requested by the tired customer,
which is most often less than three. They use this purchase for themselves or
for their farming oriented animals. This is the reason for me to write this in
simplest terms.
Therefore
Tetracycline a broadband antibiotic (with action against a large number of
bacteria and some other microorganisms) is exposed to all the bacteria in
the gut – Pathogens, commensals, and benefitting organisms, and the time gap was
more than enough for all kinds of bacteria to elicit a war against their killer
antibiotics – through establishing Resistance Against antibiotics, and the
bacteria are in possession of an abundance of DNA resources, outside of its central
nuclear DNA, to mediate the acquiring resistance genetically, bacterium to
bacterium in in-enumerative speed within a part of a second.
In
the modern day though there are many regulatory mechanisms are in place all
over the world misuse of Antibiotics continues by many means; I mentioned about
groceries around the extensive farming areas selling Tetracycline – and the
farmers consume for themselves for aberration and cut wounds, as well use it to
drench it orally to farm animals found slightly ill – It is a crime against humanity
and animal welfare, because all the farm animals are totally depended on
bacteria, Fungi and Protozoa of their large four compartmented stomach for
their digestion – and drenching Tetracycline for slightest illness would
disturb the digestion further, by reducing bacteria and Protozoa off the
maintained balance of Rumino-Reticulo stomach
Micro-flora and orally feeding all the farm animals would culminate in
undesired consequences. In these animals development of resistance is only of
secondary importance, in contrast to the mono-gastric animals – human, dogs and
cats as explained in the previous episode oral or systemic treatment with
antibiotics have to be guided by well versed respective field specialist.
Never give oral antibiotics to any mature
ruminants of the wild or Farm,
Never take antibiotics on your own,
doesn't matter however lower dosage,
Which is too dangerous than taking
higher dose,
But
higher dose you may risk your life!
Still staying on the
old practices of yesteryears to focus on the origin of Bacterial Resistance, field
of Veterinary Medicine, and farming productions have paid heavily, in origin
and development of Bacterial Resistance – Disease outbreaks threatening the
total capital pumped into Poultry farming for egg and Meat productions demanded
inclusion of antibiotics Penicillin and Tetracycline and antibacterial such as sulfonamides and
furazolidones into their feeds as low as 0.1% to 1.0% per ton of feeds as
preventive measures against major outbreak of various diseases and the farming
entrepreneurs were happy that the preventive measures very successful. This led
to antibiotic residuals reaching the gut of those who consuming egg and meat, exposing
those individuals’ commensal microbes to the antibiotics, inducting the
bacteria to elicit an effective measures against their potential threat.
Further the farming entrepreneurs found that the same antibiotic incorporated
in the feed in trace amounts – interacting with feed components acting as
growth promoting factor; this made the farming entrepreneurs and feed mixing
mills become obsessive of mixing antibiotics or antibacterial in trace amounts
and it spread to all meet production farming of poultry, swine, lamb and beef and
all went cut lose for the hell transpired now. This in spite of few
sulfonamides and furazolidones causing stunned growth as well. The same approach in
the dairy industry made disastrous impact by interfering in dairy by products
such as curd, yogurts and particularly various kinds of Cheeses, particularly
of much smaller cottage dairy industry, rather than the technically advanced
industrial dairying, since all these byproducts require microbial fermentation
for maturing as a product.
Today everything
banned, no more feed premix of antibiotics; authorities were excessively late,
and Bacteria multiplying over supersonic speed picking up at least one factor
of resistance at each multiplication – the hell have been disastrously
established. Today in place is, even antibiotic treated for a known disease be
given a time length before slaughtering, known as Antibiotic Withdrawal Time
(AWT); for each antibiotic or antibacterial AWT varies; antibiotic to
antibiotic of same group as well. Even milk of a cow treated for mastitis,
until minimum of five days gone after the last local infiltration not accepted
for collection, systemic treated cows with tetracycline have 7 days
Antibiotic Withdrawal Time.
How Bacteria Effect the Resistance (Development of Anti-Microbial
Resistance AMR)
The
first antibiotic to be invented is Penicillin, it is the first antibiotic the
encountered the resistance during treatment as well, and therefore had
undergone extensive research for improvisation derivatives, culminated in
producing numerous of penicillins from live microorganisms and synthetic
analogues; at least 15 Penicillin group of drugs, including Amoxicillin to
Imepenem and Ticarcillin are in active use in the Veterinary Medicine and very
similar to penicillins are Cephalosporins and Cephamycins are also
proliferating very fast in practice. Actually any antibiotic found with ß lactam
ring within their structure has been placed within the Penicillin group and all
these ß lactam (beta lactam drugs) has one only mode of action against the
bacteria - arrest the bacterial multiplication by
interfering the cell wall synthesis through stopping the interlinks between
Peptidoglycan strands of the cell wall – by antibiotic binding to trans
peptidase enzyme responsible for bridging the strands. Even though all the ß
lactam drugs have one and only mode of action against the bacteria, it can
exert resistance in many facets – in various biochemical forms of
challenges. Hence ß lactam antibiotics
has undergone extensive studies for resistance as well – explaining its’ mode of
resistances – can be a model for basic biochemical explanations given for
resistance to all the antibiotics by the Bacteria with slight deviations to the
particular antibiotic’s mode action against the bacteria.
When
it comes to explaining Penicillin group activity against bacteria, we cannot
avoid the explaining the Staining
Property of the Bacteria – The first and the oldest method of staining the invented by the Danish scientist Hans Christian Gram (1853–1938) still
worth fully warranted by medical practice of any type including Veterinary and
Dental sector. The Bacteria with thicker mesh of cell wall would always accept
the Gram Staining and would appear dark blue to dark purplish particles under
the Microscope – all the organisms that accept the Gram Staining are popularly
known as Gram Positive (+ve) organisms. All the organisms with thinner and membranous
cell wall will not accept the Gram Staining and are known as Gram Negative(-ve) organisms and these organisms would appear
Light pink to pink particles under microscope
Most of the Gram Positive (+ve) organisms will allow
penetration by the Penicillin or ß
lactam drugs and are somewhat susceptible to the antibiotics. But Gram Negative organisms would sieve
and shunt the penetration by the ß lactam drugs in varying decrees based on the
antibiotics and individual bacteria. The bacterium Haemophilus influenza a Gram Negative (-ve) bacteria readily
allows penetration by the ß lactam antibiotics but still resistant to all those
antibiotics (see below), whereas Escherichia coli a common Gram-ve bacteria
shows greater obstacles for ß lactam antibiotics and becomes responsible
further spread of acquired resistance whereas the species Pseudomonas show
varying permeability, still permits with greater difficulty in higher doses. Therefore
barrier mode of resistance though
naturally mediated, through chromosomes, it can be acquired by the bacteria
through plasmids (extra chromosomal) as well.
Therefore any bacteria can impose permeability barrier to any
antibiotic, as mode of resistance either by acquiring it or by chromosomally
mediated.
Secondly the
enzyme trans-peptidase enzyme responsible for bridging the
strands between Peptidoglycan strands of the bacterial cell wall acts as Penicillin
Binding Protein as well so that to initiate the cell wall weakening –
This double action enzyme may lose the affinity for antibiotic by acquired
alteration in the target enzyme or Antibiotic Binding Protein - for
ß lactam antibiotics both are one and same (PBP) whereas for other antibiotics it may be two different
proteins.
Thirdly and more importantly any bacteria can
synthesize an enzyme to inactivate the antibiotics so that to survive the
antibacterial action – a classical example is demonstrated by some Gram
Positive (+ve) and Gram Negative (-ve)
organisms inactivate the ß
lactam drugs by producing ß
lactamase enzyme that cleave the ß lactam ring and there are six types ß
lactamase enzyme that are somewhat Bacterial specific as well. The earliest
identified one was just known as Penicillinase, but among the modern day ß
lactamase enzymes some act exclusively on Penicillins only and some others are
only against cephalosporins, all the other ß lactamase enzymes readily
hydrolyses both penicillins and cephalosporins.
The type and concentrations of ß lactamase secreted are
also bacterial species specific,
Gram +ve bacteria secreting
ß lactamase is generally excreted as external enzyme to the environment they
live, in larger quantity, and active only against penicillins not against cephalosporins, mediated only through inducible,
single determinant plasmid – only through transduction (see
below) – primarily not a chromosomal constitutive – unable to initiate self-transmission
of resistance. Staphylococcal strains are very fast to develop these type of
resistance. In contrast
Gram-ve bacteria secrets ß lactamase within the
periplasmic space of the bacteria, in very small quantity, primarily
constitutive, multiple determinant – heterogeneous mediated,
less often inducible, able to initiate self-transmission by
conjugation of two bacteria, and active against both penicillins and cephalosporins
(inactivate both group of antibiotic).
Gram –ve bacteria, capable of developing resistance,
through ß lactamase secretion as of above include Escherichia, Haemophilus,
Klebsiella, Pasteurella, Proteus, Pseudomonas and Salmonella spp; it is also
noteworthy some of the strains of above bacteria may take longer time to develop resistance despite being
heterogenic origin.
Other
form of resistances to ß lactam drugs would be shown through bacterial phenotypic
changes, incomplete cell wall (Spheroplasts) or absence of cell wall
Protoplasts as found in Renal Medulla, becoming Quiescent and Tolerance are not
mediated genetically – just environmental responses to survive the
antibacterial effects.
General methods for Resistance of Microorganisms to Antibacterial
agents
Microbiologic
resistance implies an increase in the Minimum Inhibitory Concentration (MIC)
range to the levels too high to be reached at standard therapeutic dose rates,
and the general term used to describe is unexpected lack of response to
treatment in a clinical case.
Resistance
can be classified by the method of acquisition such resistance by the Bacteria.
1.
Selection
of Resistant Clones
2.
Chromosomal
Mutation
3.
Phage
transduction and
4.
R
factor acquisition by conjugation
Generalized
Biochemical methods of Resistances – means of Bacteria protecting themselves.
1. Increased production of
inactivating enzymes; may be inducible or constitutive e.g. Penicillins,
Cephalosporins, aminoglycosides group, chloramphenicol
2. Defective production of autolytic
enzymes – environmental response e.g. Penicillins,
Cephalosporins
3. Alterations in the specific
configuration of the target sites e.g. oxacillin, cloxacillin macrolides,
lincomycin, streptomycin,
4. Decreased enzyme affinity
e.g. trimethoprim,
5.
Induction
of membrane transport system to remove the antibacterial e.g. tetracyclines
6.
Inhibition
or change in membrane transport system to prevent entry of the antibacterial
e.g. aminoglycosides
7.
Utilization
of (host) alternative pathways e.g. sulfonamides, trimethoprim,
8.
Increased
synthesis of key metabolic intermediate e.g.
Para-amino benzoic acid(PABA) in
sulfonamide resistance
9.
Development
of impermeable cell walls with extremely narrow poring e.g. Pseudomonas aeruginosa to most of the
antibiotics
In all of these cases a
modification protein synthesis and enzyme activity is necessary to confer resistance;
thus this adaptation is genetically determined.
Genetics of Bacterial Dissemination of Resistance
We
all know that bacteria have two types of genetic structures that can confer
resistance, Chromosomes and Plasmids both of which are of double stranded DNA,
and at times both are associated with the bacterial inner cell membrane
which would facilitate any transfer. Unlike Chromosomal DNA, Plasmids
are not essential for live of bacteria, but do carry genetic determinants
that confer resistance as well as for virulence (the measure of vigor in
pathogenicity) of bacteria. Bacteria may carry many Plasmids, but all are of one type only, this is known as “Incompatibility”
conformity.
Plasmids
are smaller unit than central chromosome, but play a very active and complex
role in the disseminations of Bacterial Resistance than the chromosome. Plasmids
may contain 20-500 genes
that can carry resistance to 3 to 6 different antibacterial commonly – but up
to 9 antibacterial have been recorded – as well as to specific virulence
factors. To this effect many plasmids have been isolated,
characterized and identified. Plasmid-mediated resistance are known as R-factor
or Acquired resistance.
Three possible mechanisms by
which plasmids may migrate from one bacteria to another are Transformation,
Transduction and Conjugation.
1. In Transformation, naked
DNA pass from the donor to the recipient through medium they grow in and this
process is confined only to limited range of bacteria.
2. In Transduction the
transfer is mediated by a bacteriophage that makes use its
specialized molecular equipment adapted for the insertion of DNA into the recipient
bacteria, commonly it is the phage DNA that is transferred; in certain cases
some DNA from the episome (additional genetic element inside bacteriophages that can replicate
independently) in the bacterial cell replaces the proper phage DNA -
nucleic acid sequence - assumes as a special inserter. Phage mediated Transduction take
place generally in Gram-ve species, but in some Gram+ve bacteria as
well including Staphylococcus aureus.
3. In Conjugation the
DNA passes from the donor cell to recipient via a bridge formed during direct
cell to cell contact. This is the most sophisticated and thus an important
process gene transfer under natural conditions. The sophistication that ensures
the resistant gene is transmitted, by the facet it requires a surface appendage
known as sex pilus to form the bridge. This pilus is coded for by a resistance
transfer factor on the plasmid and is called a conjugative
sequence = and the opposite is referred to as non-conjugative plasmid without a resistance transfer factor. Thus many types of bacteria can act as
recipients and resistance can pass through freely from saprophytic (commonly)
in the gut of the animals to pathogenic bacteria.
Though in general conjugation transfer occurs more
frequently in between Gram-ve organisms Pasteurella and Pseudomonas very poor performers of
conjugation; this type
of transfer of gene material rarely occurs in between two Gram+ve organisms.
Conjugation allows the passage of a number of distinct genes at one time. Thus
resistance to several antibiotics – all mediated by different biochemical means
may be acquired in a single step. The great efficiency of the Conjugation
process makes the probability of gene transfer to a super-infecting
pathogen high.
Another
mechanism involved gene transfer within a bacterium, but rather
indirectly bacteria to bacteria, capability of genetic sequences to migrate from
Plasmids to Chromosome and back from Chromosome to Plasmids – and the element
showing this phenomenon is called Transposons and number of Transposons
responsible for the transfer of R-factor resistance have been isolated,
characterized and identified.
Chromosomal Acquiring of Resistance
This type
resistance to antibacterial agents depends heavily on a mutation in the
bacterial genes that leads to resistance to particular antimicrobial agent.
Here the antibacterial drug act only as selective agents that allow the
resistant mutants to emerge either by a single step or sequential mutations and
hence their genesis is independent of the presence of the agent. Mutated
bacteria are often metabolically deranged and are at selective growth
disadvantage; but for Quinolones
and related fluoroquinolones
bacteria have
developed resistance rapidly – by chromosomal mutations.
These drugs are most preferred in practice for their rapid
action on the target bacterial DNA – and instantly kill the bacteria and for
the delay in appearing viable resistant mutants. All quinolone
drugs act on the enzyme
DNA Gyrase of the Gram negative bacteria and on Topoisomerase IV of Gram positive
bacteria, - these enzymes nicks the Bacterial DNA in
certain points that facilitates the protective super coiling of DNA; when these
enzymes inactivated by quinolones, protective super coiling fails and the
Bacterial DNA as well the bacteria carrying it are readily disintegrated. In these resistance develop through
chromosomal mutation and rapid selection of mutants that are capable of
preventing the drug influx and inducting efflux by the alterations in the
quinolone target enzymes. Additional mutations in the next most susceptible
target, as well as in genes controlling drug accumulation, augment resistance
further, so that the most-resistant isolates have mutations in several genes.
Resistance to quinolones can also be mediated by plasmids that code for the
synthesis the Qnr protein, which protects the Microbes from inhibition by
the Quinolone family antibiotics.
The Clinical Relevance of Resistance for Antibacterial
Acquired – ß
lactamase induced resistance is wide spread in veterinary isolates; (50 – 60) %
of the Staphylococcus spp strains and 70% of the E. coli strains resistant to
Penicillin G. and 40% of later isolates from farm animals resistant to
Ampicillin. Hemorrhagic septicemia caused by very low efficient conjugative
transmission of resistance Pasteurella multicida – readily responsive to
treatments by sulfonamides/ trimethoprim 80:20 intravenous injection even on
very late stages of disease or in the midst of outbreaks. Use of tetracycline
is wide spread in veterinary medicine, since it is very effective against
Intra-Cellular infections of both protozoa and Bacteria in cattle. Thus more
exposed to plasmid mediated resistance conferring by diminishing the uptake and
influx and also efflux of active ingredient by the bacteria. Another modern drug
in extensive use is quinolones
for its rapid effectiveness against wide range of intracellular infections such
as normally naturally resistant Brucella, Mycoplasma and Chlamydia spp had rendered these groups of drugs to be potent
and rapid chromosomal resistant mutant selectors. Still if quinolones
shows larger or equal diameter in an ABST, than any other antibiotic
disc inserted, it should be the drug of choice – for its
rapidity in disintegrating the microbes through direct DNA action.
During intestinal infection many pathogenic bacteria can act
as recipients and R-factor resistance can pass through freely from saprophytic
bacteria commonly found in the gut of the animals that act as a reservoir
of R-factor resistance. Use of
low level of antibiotics as in animal feeds and improper dosing had led to high
incidence R-factor resistance in a given population. Further indiscriminate use
of antibiotics which may totally eliminate the effectiveness of many
antibiotics.
Guidelines to minimize the emergence of Bacterial
Resistance.
1. A broad-spectrum antibacterial should
not be used, if a narrow-spectrum agent is effective against the causative
agents. This warrants the selection of narrow spectrum
but extra quick antibiotic. A proper ABST interpretation shall guide the
practitioner.
2. Information regarding endemic
infections and sensitivity pattern should be obtained through ABST and
considered when choosing an antibiotic.
3. Appropriate dose rates should
always be followed
4. When a combination regimen is
used, to prevent the development of resistant strains, individual agents should
be used at full dosage.
5. Antibacterial for topical
application should selected from agents that are un-common for resistance.
6. For prophylaxis an antibacterial
agent that prevents colonization of a specific organism or eradicates it
shortly after it has become established should be used.
7. In consistent with reasonable
practice – every effort should be made to use antibiotics only when the medical
indications clear for such use and to avoid newer agents when already available
agents are effective.
As
such in an outbreak of endemic or non-endemic situation vaccination program
shall be coupled with vigorously treating current ill animals with most
effective antibiotic meticulously selected against isolated organism is
important, so that to minimize the exposing the population to the antibiotic
repeatedly.
The
latest drugs to develop resistance is Colistin or Polymyxin E of same family of
Polymyxin B, that are capable the solubilizing
the membrane of Gram-ve organisms even in isotonic environment. The first
Colistin-resistance gene that is carried in a plasmid that can be transferred between
bacterial strains has been described in May 2016. Use of Colistin to treat Acinetobacter baumannii infections has led to the development
of resistant bacterial strains. These resistant strains have also been shown to
develop resistance to antimicrobial compounds, including LL-37 and lysozyme, produced as part of the human
host's immune system. A tragedy in forecast.
Use of Colistin is higher in the Mediterranean
and South-East Asia (Korea and Singapore), where Colistin resistance rates are
continually increasing.
