Antibiotics. – Dr. Sayeed Ahmad

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Antibiotics.
Dr. Sayeed Ahmad D.
I. Hom. (London)

Antibiotic

is
a substance produced by certain bacteria or fungi that kills other cells
or interferes with their growth. In nature, these substances help some
microbes survive by limiting the multiplication of other microbes that
share the same environment. Antibiotics that attack pathogenic
(disease-causing) microbes without severely harming normal body cells
are useful as drugs.

Antibiotics are especially useful for treating
infections caused by bacteria. Antibiotics came into widespread use
during the 1940’s. At that time, they were often called “wonder
drugs” because they cured many bacterial diseases that were once
fatal. The number of deaths caused by meningitis, pneumonia,
tuberculosis, and scarlet fever declined drastically after antibiotics
became available. Today, physicians prescribe antibiotics to treat many
diseases caused by bacteria.

In addition, some antibiotics are effective against
infections caused by fungi and protozoa, and a few are useful in
treating cancer. Antibiotics are also used to treat infectious diseases
in animals. Farmers sometimes add small amounts of antibiotics to
livestock feed. The antibiotics support the animals’ growth for reasons
that are not entirely understood.

Antibiotics are not effective against colds,
influenza, or other viral diseases. In addition, the effectiveness of
antibiotics is limited because both pathogenic microbes and cancer cells
can become resistant to them.

Kinds
of antibiotics :

Antibiotics are selectively toxic-that is, they
damage some types of cells without harming others. Medically useful
antibiotics attack infectious microbes or cancer cells without
excessively hurting human cells. Antibiotics fight different types of
illnesses in a variety of ways.

Antibacterial
antibiotics.

Antibiotics
are selectively toxic against bacteria because bacterial cells differ
greatly from human cells. One of the chief differences is that bacteria,
unlike animal cells, have a cell wall. This wall is a rigid structure
that forms the cell’s outer boundary.

The type of cell wall a bacterium has is one factor
that determines which antibiotics can kill it. Scientists use a process
called Gram staining to classify cell walls of bacteria. Hans C. J.
Gram, a Danish bacteriologist of the late 1800’s, developed the process.
This method classifies bacteria as gram-positive (G+) or gram-negative
(G-).

Some antibiotics selectively kill either
gram-positive bacteria or gram-negative bacteria. These substances are
called

narrow
spectrum antibiotics. The
antibiotic Vancomycin
selectively
kills such gram-positive bacteria as
Staphylococcus,
Streptococcus,
and
Enterococcus).
Aztreonam
is
a narrow spectrum antibiotic that kills only gram-negative bacteria,
such as Escherichia coli and Pseudomonas aeruginosa. Other antibiotics
can kill both gram-positive and gram-negative bacteria. These drugs are
called broad
spectrum antibiotics.
Ceftriaxone
is
one example of a broad spectrum antibiotic. No broad spectrum antibiotic
can kill all bacteria, and no narrow spectrum antibiotic can kill all
gram-positive or all gram-negative bacteria.

Other
kinds of antibiotics.

Some
antibiotics are effective against infections caused by fungi and
protozoans, whose cells differ from human cells. Antibiotics that fight
fungi include miconazole
and
amphotericin.
Paromomycin
is used to treat amebiasis, an intestinal disease caused by a protozoan.

Anticancer antibiotics attack cells while they are
dividing. These drugs are somewhat selectively toxic because cancer
cells generally divide much more frequently than do normal cells. But
some normal cells-such as blood-forming cells-divide rapidly. Anticancer
antibiotics also affect these cells. The antibiotic

doxorubicin is
used to treat certain types of leukemia, breast cancer, and other
tumors.

Some
widely used antibiotics :

Antibiotic
–> Some infections and diseases treated :

Ampicillin

G+
and G- infections, including respiratory infections and urinary tract
infections.

Azithromycin

Many
kinds of pneumonia, and certain other G+ infections.

Ceftriaxone

G+
and G- infections, including gonorrhea.

Chloramphenicol

Rocky
Mountain spotted fever and G+ and G- infections, including meningitis.

Ciprofloxacin

Urinary tract infections and acute
diarrheal diseases caused by certain G- infections.

Dicloxacillin

Penicillin-G resistant, methicillin-sensitive staphylococcal
infections.

Doxycycline

Pneumonia,
G+ and G- infections, bite wounds, acne.

Fluconazole

Fungus
infections of the skin, mucous membranes, blood, and brain.

Gentamicin

Serious
infections, especially G- infections.

Neomycin

G+
and G- infections, especially skin infections and those resulting from
burns.

Penicillin
G

Syphilis,
strep throat, and other G+ infections.

Rifampin

Tuberculosis.

Streptomycin

Tuberculosis
and bubonic plague.

Vancomycin

Serious
staphylococcal, enterococcal, and streptococcal infections that resist
other drugs.

How
antibiotics work :

Antibiotics fight microbes and cancer cells by
interfering with normal cell functions. In most cases, this interference
occurs in one of three ways: (1) prevention of cell wall formation, (2)
disruption of the cell membrane (covering), and (3) disruption of
chemical processes.

Prevention
of cell wall formation

.
Penicillins
and some other antibiotics destroy microbes by interfering with their
cell wall formation. Animal cells do not form walls. As a result, these
antibiotics do not damage them.

Disruption
of the cell membrane.

All
cells have a membrane that controls the movement of substances in and
out of the cell. Some antibiotics, including
amphotericin
B and
nystatin,
disrupt the cell membrane of certain
microbes. A damaged membrane might allow vital nutrients to escape or
poisonous substances to enter and kill the cell. These antibiotics do
not harm human cells because the drugs affect membrane components found
only in microbial cells.

Disruption
of chemical processes

.
All cells produce proteins and nucleic acids, which are vital to life.
Human cells produce these substances in much the same way as microbial
cells do. But in some cases, these processes differ enough so that
antibiotics interfere with the chemical activities in microbial cells,
but not in human cells. For example,
streptomycin
and
tetracycline
prevent
certain kinds of microbes from producing proteins, and
rifampin
interferes
with the formation of nucleic acids.

Dangers
of antibiotics :

Many antibiotics are regarded among the safest drugs
when properly used. But antibiotics can sometimes cause unpleasant or
dangerous side effects. The three main dangers are (1) allergic
reactions, (2) destruction of helpful microbes, and (3) damage to organs
and tissues.

Allergic reactions, in most cases, are mild and
produce only a rash or fever. But severe reactions can occur, and can
even cause death. All antibiotics are able to produce allergic
reactions, but such reactions occur most often with penicillins. A
physician usually asks if a patient has ever had an allergic reaction to
an antibiotic before prescribing that drug. Most people who are allergic
to one antibiotic can take other antibiotics that have significantly
different chemical compositions.

Destruction
of helpful microbes.

Certain
areas of the body commonly harbor both harmless and pathogenic microbes.
These two types of microbes compete for food, and so the harmless
microorganisms help restrain the growth of those that cause disease.
Many antibiotics-especially broad spectrum drugs-do not always
distinguish between harmless and dangerous microbes. If a drug destroys
too many harmless microorganisms, the pathogenic ones will have a
greater chance to multiply. This situation can lead to a new infection
called a superinfection. Physicians usually prescribe a second drug to
combat a superinfection.

Damage to organs and tissues is rare in people using
antibiotics that act only against the cells of pathogenic microbes.
Extensive use of some antibiotics, however, may damage tissues and
organs. For example, streptomycin has caused kidney damage and deafness.
Physicians prescribe drugs with such known risks only if no other drug
is effective.

Anticancer antibiotics act against all cells that
divide rapidly, and so can affect normal cells as well as cancer cells.
For example, cells in the bone marrow divide constantly to produce fresh
blood cells. Anticancer antibiotics can damage the bone marrow. Such
damage increases the risk of infection by reducing the number of white
blood cells, which help the body fight disease.

Resistance
to antibiotics

. Some
pathogenic microbes develop an ability to resist the effects of certain
antibiotics. The most widespread and worrisome resistance in pathogenic
microbes occurs in bacteria.

Bacteria can become resistant to antibiotics through
a type of evolution. In bacteria-as in other living things-genes carry
instructions controlling life processes. Occasionally, a gene in a
bacterium naturally changes in a way that enables the microbe to resist
the effects of an antibiotic. Such a change is called a mutation. The
change may provide resistance to one specific antibiotic or to a group
of chemically similar antibiotics-for example, the penicillins. Bacteria
can also acquire resistance from other bacteria by transferring genetic
material. In some cases, these exchanges enable bacteria to acquire
resistance to more than one type or more than one group of antibiotics.

Bacteria also can become resistant to antibiotics by
producing an enzyme that breaks down the drug. This occurs with

Staphylococcus,
which
may resist penicillins
and
cephalosporins.
Bacteria
can also change their cell membranes so that antibiotics can not
penetrate them. An example of this kind of bacteria is
Pseudomonas.
Pseudomonas
may develop resistance to the quinolone
antibiotics
this way. Enterococcus,
a gram-positive bacteria, can become resistant to
vancomycin
by
changing the proteins to which vancomycin usually binds. Streptococcus
can resist penicillins and cephalosporins in this way.

Testing
and producing antibiotics :

Testing.

Every
year, scientists test thousands of natural and chemically modified
microbial substances for potential use as antibiotics. First, they test
these substances against harmful microbes or cancer cells that have been
grown either in test tubes or on laboratory plates.

A substance that shows strong antibiotic activity
against pathogenic microbes or cancer cells undergoes extensive tests in
laboratory animals. If it produces no harmful effects in the animals,
scientists test the antibiotic in human beings. In the United States,
the Food and Drug Administration (FDA) must approve human testing. If
the drug proves to be safe and effective, it is referred to the FDA for
approval. Finally, if the FDA approves the antibiotic, the developer
begins to produce it for sale.

Production of antibiotics involves several steps.
First, cultures of antibiotic-producing microbes are grown in flasks and
then transferred to huge fermentation vats. The microbes multiply
rapidly in the vats because the environment is controlled to stimulate
their growth. After fermentation, the antibiotic substance is extracted
from the culture and purified.

Some natural antibiotic substances are modified
chemically to produce semisynthetic antibiotics. Many such drugs are
more effective than the natural antibiotics from which they were
developed.

Drug companies conduct special tests on antibiotics
during and after production to ensure their quality. Finally,
manufacturers make the purified antibiotic substances into pills,
liquids, and ointments for medical use.

History :

For more than 2,500 years, people have treated
certain skin infections with molds that form antibiotics. However,
modern scientific study of these substances did not begin until the late
1800’s. At that time, the French chemist Louis Pasteur discovered that
bacteria spread infectious diseases. Then Robert Koch, a German
bacteriologist, developed methods of isolating and growing various kinds
of bacteria. Koch also identified specific bacteria that cause certain
diseases.

Scientists then began working to develop drugs that
could destroy pathogenic microbes, but the substances they produced
proved either ineffective or dangerous. A historic breakthrough came in
1928, when British bacteriologist Alexander Fleming observed that a mold
of the genus Penicillium produced a substance that destroyed bacteria.
He called the substance penicillin.

In the early 1940’s, American bacteriologist Selman
A. Waksman tested about 10,000 types of soil bacteria for antibiotic
activity. In 1943, he discovered that some Streptomyces a type of fungi,
produced a substance that had potent antibiotic properties. A new
antibiotic called streptomycin resulted from Waksman’s research.
Thousands of antibiotic substances have been found in nature or have
been produced chemically. Relatively few antibiotic substances, however,
have proved safe and effective.

Since the 1990’s, resistance to antibiotics has been
a growing threat to public health. Widespread use of antibiotics to
treat human infections increases the number of resistant bacteria.
Antibiotic use in livestock promotes the development of resistant
bacteria that can spread to humans. For example, studies in the
Netherlands, Spain, the United States, and the United Kingdom in the
late 1990’s revealed that many chickens were infected with antibiotic
resistant strains of a bacterium called

Campylobacter.
When people cooked the meat of these chickens, some of the Campylobacter
microbes survived, and the people became infected.

Certain kinds of Enterococcus bacteria are especially
troublesome because of their resistance. In Europe, drug-resistant
strains (types) of Enterococcus that originated in livestock have spread
to people. In the United States, Enterococcus resistant to multiple
antibiotics has caused human infections that are difficult or impossible
to treat. Infections caused by antibiotic-resistant varieties of
Enterococcus occur mostly in patients who are already seriously ill.

In the 1990’s, scientists combined the antibiotics
quinupristin and dalfopristin to create a drug that works against
resistant strains of Enterococcus. In 2000, the FDA approved

linezolid,
the
first entirely new type of antibiotic developed in more than 30 years.
The antibiotic, sold under the brand name Zyvox,
is effective against gram-positive bacteria, including Enterococcus,
that have become resistant to all other antibiotics. But experts believe
antibiotic-resistant Enterococcus remains a major threat to public
health.

ANTIBIOTICS
AND HOMŒOPATHIC ANTIDOTES

Adverse
Effects of Penicillin

Fever with cold feet. —– Bell., Cupr-ac.

Wheezing and Pseudoasthmatic attack. —–
Aspidosperma (Quebracho)

When skin eruptions are simultaneously present —–
Grind.

Anorexia (with Mycin group of drugs like Aureomycin)
—– Abrot.

Peripheral Neuritis. —– Ant-t.

Brachiaglia Nocturna (with the pronounced symptoms of
pins and needles). —– Sec., Act-s.

Pruritus. —– Apis and Grind. 10 drops mixed in a
cup of milk and applied locally.

Skin lesions from Penicillin. —– Agar., Sulph.

Chronic cough after Penicillin. —– Penicillin 3x
or 30, Seneg. 30 or 200.

In cases when Srepto Peniciliin had been used.
Streptococcin 30 or Staphelococcin 30 (as an intercurrent remedy).

Heart depressing effects of Penicillin. —– Ars-a.

Harmful effects of Penicillin. —– Ars-a., Thuj.,
Nux-v., Sil.

Specific to counteract the effects of Penicillin.
—– Ars-a.

Diarrhœa from Antibiotics (especially Mycins). —–
Nit-ac.

Allergic reactions to Antibiotics. —– Sulph.,
Penicillin, Streptomycin.

Headache due to Streptomycin. —– Bell.

Ill effects of Chloromycetin: cases of typhoid (where
Chloromycetin was given). —– Chloromycetin 30, 200 or 1M (according
to patient’s Constitution). With Placebo for a week. In second week
—– Typhoidinum 200 or 1M (with Placebo for a fortnight).

Intestinal effects of Aureomycin. —– Aureomycin
leaves a very weak liver and severe trouble with the bowels. In this
case, a pure constitutional treatment with careful observation of
idiosyncrasies is most effective.

Ill effects of Allergy (in general). Ill effects of
Penicillin. —– Carb-v. (Dilutions used: 2x, 3x, 6x, 12x).

References:
World
Book 2003.
Homœopathy and Adverse Reactions of Allopathic Drugs, by Dr. Sayeed
Ahmad.

Copyright © Dr. Sayeed Ahmad
2004

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