Flashpoint! Electronic Magazine
Common Questions About Infectious Disease
What are antibiotics and where do they come from?
Literally meaning "anti-life," antibiotics are substances derived
from microbes, primarily found in soil, that kill other bacteria,
although the term has been extended to include synthetic
compounds that inhibit microbes.
What is drug resistance?
As the name implies, drug resistance is a condition in which
microbes acquire the ability to resist drugs that once destroyed
or controlled them. In the case of antibiotics, overuse and
misuse is contributing to the growth of resistant strains of
everything from pneumonia and strep to meningitis and
tuberculosis. Indeed, some strains of TB are resistant to as many
as 11 different drugs.
How does drug resistance develop?
Mutations, often given a bad reputation when they relate to the
development of diseases such as cancer, are, in fact, nature's
way of ensuring the survival of an organism by creating
diversity. Most of these natural experiments fail because they
fail to give the organism a survival advantage. But when
conditions suddenly change, as happens when a colony of bacteria
or a cluster of parasites is attacked by antibiotics, some
mutants invariably survive.
The survivor, now free of
competition, becomes the progenitor of a new breed that
incorporates this resistance into its genes. As more drugs are
introduced, the chances of the process repeating itself increase,
leading to multiple drug resistant strains. Casual and
indiscriminate use of antibiotics similarly kills harmless
strains and allows resistant strains to flourish.
bacteria exchange genetic material easily, allowing a resistant
strain to pass along its trait to one responsible for a
completely different disease, sometimes before the drug has ever
been used against it.
How common is drug resistance now?
It is easy to become an alarmist when most evidence suggests that
almost every bacterial disease organism now known is resistant to
at least one of the current 155 antibiotics. (The actual number
of antibiotics is closer to 2,000 if you count the slight
variations of each one used to counteract bacterial resistance.
There are now, for example hundreds of varieties of
penicillin.) The fact remains, however, that prudent use of
antibiotics is still an effective method for treating most
bacterial diseases and that most common strains retain at least
some susceptibility for the time being.
Are people protected from drug-resistant strains of disease if they have never or seldom taken antibiotics?
No. It is the strain of disease, not one's personal use of
antibiotics that matters. And if a person is unfortunate enough
to acquire a resistant strain, other more expensive combinations
will have to be used. One clear example is the growth of
resistant Streptococcus pneumonias, the cause of childhood ear
infections, of which there are already seven million cases per
Testing at sites around the country has revealed that as
many as 25 percent of children in some areas carry the resistant
strain. Although most children are not at risk for complications
such as meningitis, the odds that minor problems could become
catastrophes increase as more and more drugs become ineffective.
Do antibiotics given to animals affect humans?
There is disagreement on this point. Some 25 million pounds of
antibiotics are fed to pigs, turkeys, chickens and other animals
in the U.S. each year. Trade and industry groups contend that
such use keeps meat, poultry, milk and egg supplies cheap and
Others argue that plying animals with antibiotics can
lead to drug-resistant animal strains of disease, such as
psittacosis_a bacterial disease that dwells in birds_or
salmonellosis, a diarrheal disease that can be transmitted to
humans. No such cases of transmission of psittacosis have yet
been recorded, although drug-resistant strains of salmonella can
be traced to animal sources.
Is there a cost to antibiotic resistance?
Yes, a staggering one. Although the figures are far from exact,
the best estimates are that the need to use more expensive
antibiotics, and the increased length of hospital stays because
of more resistant infections add $30 billion annually to the
nation's health care bill. The CDC also estimates that treating a
case of drug-resistant tuberculosis costs $180,000, compared to
the average $12,000 price tag for a normal sixmonth course of
Do antibiotics kill viruses?
No. Although antiviral compounds, such as AZT and acyclovir,
exist they are not antibiotics in the true sense. Viruses need to
hijack a cell's machinery to reproduce; otherwise they are just
lifeless particles, presenting no molecular targets for
antibiotics to attack. Unfortunately, physicians sometimes
prescribe antibiotics to fulfill the patient's psychological need
for therapy, even though the drugs are useless for viral
In fact, some studies have suggested that of the 150
million antibiotic prescriptions filled each year in the U.S.,
half are unnecessary or unwarranted. Antibiotics also are widely
available over the counter in many countries, contributing to
their inappropriate and indiscriminate use.
What are the risks of getting infected inside a hospital?
They vary depending upon your condition. Transplant, surgery,
cancer, burn, AIDS and other immunocompromised patients, as well
as those over 65, are at increased risk. Others are less so. But
acute care hospitals, where these patients tend to concentrate,
remain stubborn sources of infection. Indeed,2.1 million, or
nearly six percent of all acute-care hospital patients develop
hospital-based infections each year.
One reason for the
relatively high number is the increase in extensive, complicated
surgeries over the last 30 years. There were no hip replacement
surgeries before 1966, for example. Now there are approximately
125,000 each year in North America alone.
The growth in coronary
artery bypass operations is even more dramatic_ from none in 1966
to 390,000 now in the U.S. each year. Other factors contributing
to infection include the rising use of artificial heart valves, cardiac pacemaker leads, nervous system
ventricular shunts and catheters of all types. Carelessness in
carrying out routine infection control guidelines, such as
frequent hand washing and removal of gloves once a procedure or
task has been completed, is to blame as well.
What happens if we run out of drugs that work
In the most extreme cases, we will be back where we were before
the advent of penicillin in 1942. Bacterial diseases such as pneumonia, which
now kills 25,000 to 50,000 out of an estimated 600,000 cases
annually, will be left to run their course, causing death rates
for this and many other infections to soar. Should American
soldiers be involved in a war, many more also will die from
battlefield injuries. The main weapons against viral diseases,
vaccines, should remain effective, however.
Is there anything individuals can do to help counter drug resistance?
Yes. Since physicians often feel pressured to write prescriptions
to keep patients happy - and patient satisfaction ratings
high - individuals can help by not demanding antibiotics when
doctors explain they are not warranted; colds, sore throats and
bronchitis are the best examples.
Parents can help, too, by
ensuring that the course of antibiotics prescribed for a child's
ear infection (or for their own condition) - 10 days is the usual
period - is followed religiously. Parents
also should be especially alert if the child's symptoms do not
improve soon after the medication begins. This could be a sign
that the antibiotic is not working properly.
Is it possible to get TB during a bus ride, from a public telephone or on an airplane?
This question has several answers, which differ depending on the
condition of one's immune system. In general, healthy people who
happen to become infected will contain the bacteria and be
unaffected, at least while they remain well. However, those who
are immunocompromised, such as cancer or AIDS patients, are at
greater risk for developing the disease.
Because sunlight kills
the bacteria that causes TB, and because these bacteria cannot
live outside the human body indefinitely, it is impossible to
become infected by using a public telephone. The risk increases
slightly on a bus or subway train or similar enclosed
environment, but the infectious person would have to have an
active case of TB and be coughing in another's face with the
windows closed for many hours before transmission would even be
As for airplane travel, a Massachusetts
Medical Society Report (March 3,1995) investigated six instances
in which passengers or flight crew traveled on commercial
aircraft while infectious with TB. In two examples, affecting
eight people, transmission did occur. The factors most
responsible were the sick person's stage of infection, the length
of the flight (more than eight hours) and proximity to the person
Where does the flud come from?
The three major strains of the influenza virus_A, B and C_live
and change inside animals, primarily horses, pigs and ducks. Each
year the strains mutate slightly, resulting in different surface
proteins (antigenic drift) that interact with the human immune
system. This causes different degrees of severity. Type A is
usually the most severe, Type B milder and Type C so mild that it
may barely register as an illness.
It is this ability to change
constantly that ensures the survival of the virus. It also
demands international cooperation among the agencies responsible
for monitoring flu activity, namely the World Health
Organization, the Centers for Disease Control and the National
Institute for Medical Research (England and Australia). Together
they analyze the dominant strains occurring in the fall and
winter months in different hemispheres in order to predict which
vaccine will be most effective as the seasons change.
What makes a regular flu turn into a "killer" flu?
When two different influenza strains exchange genetic material
(antigenic shift), they may create an entirely novel virus
against which humans have no immunity. That is what happened in
the great flu pandemic of 1918 in which 560,000 Americans died in
less than a year, part of an estimated 20 to 40 million deaths
Can a "killer" flu happen again?
It already has. In 1957 and 1968, there were flu pandemics, with
the death rate in the U.S. for the latter example_the Hong Kong
pandemic_ estimated at 30,000. Another 51 million were reported
ill at an economic cost of $4 billion. The conditions for
creating the viral exchange continue as well, especially in China
where ducks, which harbor the influenza virus, live in close
proximity with pigs. This integrated pig-duck agricultural system
serves as an ideal natural laboratory for creating potential new
killer strains whose ability to spread through the air, according
to infectious disease experts, makes them a far more significant
threat than the highly publicized Ebola virus.
Is it possible that HIV could mutate and become as easily transmissible through coughing as the flu?
Nothing is impossible, but an HIV mutation of this kind is
considered highly unlikely. The reason stems from the nature of
the retrovirus itself, which has become so dependent on the
cellular host for sanctuary and for the raw chemical material it
needs to survive that existing independently in the air seems
beyond its power.
Originally published: October, 1995
from UCSF Magazine
U.C. San Francisco Medical Center