Bacteria, Germs and Antibiotics: Science Study Guide
What could be four billion years old and still survive? Microbes. There are more microbes on earth than plants, animals and people, combined. Microbes are a small living thing—mostly seen under microscope. Unfriendly microbes are pathogens, but colloquially they are referred to as “germs.” It was only in 2012 that scientists were able to roll call microbes living in different parts of the human body. A human being, for example, has about a hundred trillion cells. There are 10 to 20 times that number of bacteria that live on us.
History of Filth
In historical times, people were poisoned by their surroundings by sewage, garbage dumps, poor conditions and the poisonous smelly vapors, which they called miasmas. Since they couldn’t see germs, they blamed disease on bad air, witchcraft or punishment from God. What they needed was to get rid of rotting bodies, clean out the smell and refuse and get fresh water.
The ancient Greeks thought that getting the humors—blood, phlegm, yellow bile and black bile—into balance was the answer. This often lead to “bloodletting” or even drilling holes in people’s skulls called trepanation (to let evil spirits out).
Fathers of Detection
English scientist Thomas Moffet (1553-1604) drew pictures of fleas, lice and mites. He described a skin infection called scabies and even correctly identified sulfur as a way to combat the lice.
A German monk Athanasius Kircher (1601-1680) looked through a crude microscope and saw worms in sour milk. He also saw what he called “animalcula” in the blood of people who died from the bubonic plague.
Then Antonie van Leeuwenhock (van LAY-ven-hook) (1632-1723), a Dutchman with no great education who made drapes and ground lenses, became the Father of Microbiology by making simple microscopes. He was inspired to take up microscopy after having seen a copy of Robert Hooke's popular illustrated book Micrographia, which described Hooke's own observations with the microscope.
Story has it that van Leeuwenhock scraped his own teeth, stuck the scum under a crude microscope and saw what he called living “animalcules.” He went on to discover bacteria, free-living and parasitic microscopic protists (one-cell organisms), sperm cells, blood cells, microscopic nematodes, and much more. His research opened up an entire world of microscopic life to other scientists.
Bacteria that live on us or use us as a mobile transport medium can actually be helpful. For example, some secrete vitamins—Vitamin K, B12—and other bacteria to prevent the colonization of nastier bugs. In a germ-free animal, you only need 10 cells of salmonella to infect it, whereas humans need a million cells. Good intestinal bacteria produce substances that prevent other bacteria from taking over and many protect us from environmental water-borne diseases.
Bacteria also stimulate the development of tissues and the production of natural antibodies. In addition to bacteria, a whole heap of viruses, mites, lice, protozoa and worms call humans home. They often do us no harm at all. Mites that live on your eyelashes are part of the normal flora of the ocular surface, and occasionally can cause overgrowth and disease, called blepharitis.
The Bad Guys
Call them viruses, bacteria, fungi or parasites, germs can take on many different forms. Pathogenic bacteria can cause disease, making your immune system work overtime. Some of them produce toxins, which is another word for poisons. Vibrio Cholerae, the bacteria that causes the diarrheal disease cholera makes a protein called cholera toxin. This toxin causes intestines to release huge amounts of water, as much as .05 gallons (or two liters) every hour.
We can pick up bacteria by touch, through wounds or cuts or via sex. We can breathe it in, such as with tuberculosis or Legionnaire’s disease. We can contract disease from ticks, fleas or mosquitos. We pick up bacteria from poor hygiene or improper food preparation and storage.
A New York cook in the early 20th century carried bacteria that caused the disease typhoid fever. She was never sick but infected family after family –more than 50 people—with her cooking. Nicknamed Typhoid Mary, Mary Mallon was immune to the fever she carried inside her. She was what is commonly called, a “healthy carrier,” which is a person who is contagious but has no symptoms.
Hazard Level: Minimal
Unlike viruses that need to get into one of our cells to replicate, bacteria can reproduce on their own through a process called binary fission. One cell divides into two, then those two divide and so on.
The flu, virus influenza, gets as many as one billion people sick each year. The flu changes its disguise every year so we often need a new vaccine to help people cope. With a vaccine, cells called B cells start producing antibodies as it shows your body what the bug looks like, and the antibodies circulate and bind to the virus preventing damage. The vaccine also has a memory so if it sees the same germ again, whack! Antibodies. Vaccines have been developed to eradicate smallpox, measles, Rubella and more.
After the first antibiotic was introduced, the bacteria all around us were sensitive to the new drugs. Antibiotic, meaning “against life,” is a substance capable of stopping the growth of replicating microbes such as bacteria.
Some, such as penicillin, prevent bacteria from growing. They starve the bacteria of the vital nutrients needed to survive.
Since viruses cannot replicate by themselves, antibiotics do not work on them.
Misuse and Overuse of Antibiotics
According to the Centers for Disease Control and Prevention (CDC), each year in the United States, at least 2 million people become infected with bacteria that are resistant to antibiotics, and at least 23,000 people die each year as a direct result of these infections. Many more people die from other conditions that were complicated by an antibiotic-resistant infection.
Years of use and misuse of antibiotics have created a new monster, bacteria that have developed antibiotic resistance. The introduction of surface antibacterial agents or biocides (that is to say, cleaning supplies) into healthy households may be part of the problem. These products can select resistant strains, and overuse in the home means bacteria can mutate and propagate into resistant microbial variants.
Concerning Threats: Superbugs
The headline reads like this: “Tainted medical scopes at a UCLA medical center may have exposed up to 179 people to a potentially deadly superbug that has already been linked to two deaths.”
UCLA said the contaminated instruments had been sterilized to the manufacturer’s standards, but despite the treatment, may have transmitted carbapenem-resistant Enterobacteriaceae (CRE). CRE is a family of bacteria that lives in the gut and is resistant to practically every antibiotic on the market today, including carbapenems, which are widely considered antibiotics of last resort.
The CDC has prepared a pdf called “Current Antibiotic Resistance Threats in the United States, by Microorganism.” Visit their website to see the most current list.
Regular hand cleaning after using the bathroom, before making food and after touching objects such as doorknobs, keyboards and other common surfaces goes a long way to reduce the spread of germs. A do-it-yourself vaccine, vigorous handwashing helps to prevent respiratory (coughing, sneezing) and diarrheal (loose stool) illnesses so you can stay healthy. Eight out of ten infections of pathogenic bacteria are transmitted by touch.
It is easier to prevent a disease than treat it. Vaccines protect the recipients as well as people around them. Polio, measles, pertussis, mumps, tetanus and other infectious diseases that were once common in this country and around the world are kept in control by vaccines.
Practice Food Safety
Hundreds of organisms can cause food poisoning. E. coli (nickname, “hamburger disease”) is found in uncooked beef. Salmonella is most often found in eggs (and on reptiles). Wash produce, hands, surfaces and utensils thoroughly. Separate uncooked meat and fresh veggies. Cook food to a safe minimum temperature and refrigerate promptly. (For safe cooking temperatures see CDC: Food Safety in Resources.)
Know where you are swimming. Make sure the water is clean and tested, and don’t drink it. Do not pee or poop in pools (check babies every hour). Don’t swim with diarrhea.
Learn and prevent sexually transmitted diseases (STDs). Use condoms, limit partners, get vaccinations and practice abstinence.
Become familiar with antibiotics and their uses.
Avoid Antibiotic Overuse
Colds, flu and bronchitis do not respond to antibiotics so question their prescription by a doctor. Taking them when they aren’t needed increases your chance of getting an infection that resists antibiotic treatment when you need it most. Symptom relief or over-the-counter products for a cold or flu are your best bet here.