Bacterial Diseases of Humans

Gram+ Cocci:

Staphylococci, including Toxic Shock Syndrome (TSS):
The main pathogenic species is Staphylococcus aureus (aure = gold, golden), which causes most hospital-acquired infections. Multiple-drug-resistant strains have become such a problem due to overuse of antibiotics, that medical workers now refer to this by the nickname “MRSA.” In 1999, following botched out-patient surgery on my stepfather, he was put on a ventilator which was contaminated and introduced a massive MRSA infection into his lungs. He died after a number of weeks in ICU. In 2000, in the last couple months of my father-in-law’s life, nursing home staff battled MRSA in bedsores on his heels, acquired during an immediately-previous hospitalization. In 2008, my mother was admitted to a hospital with pneumonia. While in ICU, E. coli and another bacterium, Acinetobacter, were introduced into her bladder via an inserted catheter, and were also introduced into her lungs in addition to the Streptococcus pneumoniae that were already there. In addition to those, hospital staff decided to insert a port because of bruising wherever they re-inserted the IV, and along with the port, they introduced MRSA into her bloodstream. Needless to say, she did not recover, even on the strongest antibiotics the doctors could think of to prescribe. These three incidents occurred in different hospitals in different cities.

Nosocomial (noso = disease, sickness; comi = care, attention) is a good word to know: it means something that came from a hospital, as in the phrase, “nosocomial infection.”
A couple useful, related words are iatrogenic (iatro = a physician; gen = bear, produce), which is used to refer to something that was introduced/caused by a doctor, and idiopathic (idio = one’s own, peculiar), which means, “We don’t know why you have that.” An example of the latter would be when you tell a doctor you have a sore throat, and the doctor tells you that you have “idiopathic pharyngitis,” then hands you a bill. The “idiopathic” part of that means, “I don’t know why you have it,” and the “pharyngitis” part of that is medical jargon that simply means, “sore throat,” — but you knew that much when you went to see the doctor!
Thankfully, there are good doctors out there who do work hard and do care about and are willing to talk to their patients, so if you can find one of those, that’s a valuable resource to have. Along with that, though, realize that the internet has changed the way medical advice is obtained. It used to be that, if you asked a doctor, “So, what can I do about it?” and the reply was, “Nothing,” you had to settle for that. Not so any more. Now, you write down the doctor’s diagnosis, go home and immediately do a Google search and a search in our library’s online databases, join a discussion forum, print out and read pertinent journal articles, and do anything else you can to educate yourself and take charge of your health, then go back and discuss it all with your doctor.

Also, note that keeping your skin too “clean” can wash away the natural “antibiotics” in skin oils, actually making you more susceptible to bacterial infections.
Not all streptococci are bad: many are neutral or beneficial. Streptococcus thermophilus (thermo = heat; philia = brotherly love) is one of the bacteria that help turn milk into yogurt. On the other hand, Streptococcus pyogenes causes strep throat (pyo = pus, inflammation; gen = bear, produce).
Streptococcus pneumoniae:
This is a diplococcus (pneumo = lungs) which infects the lungs, causing pneumonia, and is spread by coughing. PHOTO

Because these bacteria have a lot of peptidoglycan in their cell walls, penicillin is effective for most of these, except where overuse has caused resistant strains. This is especially a problem with S. aureus in hospitals.

Gram Cocci:

(gono = seed, generation, offspring; rrhea = flow, current) This disease is a sexually-transmitted disease (STD), and is caused by a bacterium of this type. One symptom is a pussy discharge from the genital area.
(meninges, meninx = a membrane [around the brain]; -itis = inflammation) This is an infection of the membranes covering the brain and/or spinal cord, and is life-threatening because of proximity of these membranes to the brain/spine.

Various Bacilli:

Acinetobacter baumannii:
This is a Gram bacillus that is short and almost round, almost halfway between a coccus and a bacillus. It is a normal part of the bacterial flora of soil, and typically does not bother healthy people. However, it is increasingly a problem in debilitated, immunocompromised (meaning, their immune systems aren’t doing a good job of fighting off infections) people, where is is an “opportunistic pathogen,” and is increasingly becoming a major problem in ICUs.
(-ella = small) This disease is named after a Dr. Salmon who discovered it, and causes a type of food poisoning which has been in the news recently when it has made people sick after eating eggs, hamburger, etc. which contained it. Egg shells are porous — in a developing egg, that’s how the unhatched chick gets the air it needs to grow. Thus, washing eggs can actually cause Salmonella to penetrate the egg shell. If eggs are washed just before use, this is not a problem because the number of bacteria are usually negligible. However, if eggs are washed just after the hen lays them, then packaged into egg cartons at the egg factory, where they sit for a while until they’re shipped to a grocery store, then sit for a while at the grocery store until purchased, then sit for a while in your refrigerator until used, that will give any Salmonella that did enter the egg a chance to grow and multiply, so by the time the eggs are used, the bacterial count is significantly higher, perhaps enough to make you sick. To aid in prevention of bacterial growth in eggs, if washing is even needed, they should not be washed until just before use.
Escherichia coli (E. coli):
Iced Tea
0.1 mL of Iced Tea from Local Fast-Food Restaurant
This is a normal part of our intestinal flora, and is non-pathogenic if living in its normal environment in someone’s large intestine. However, if it gets elsewhere in the body, like the upper GI tract, lungs, bladder, bloodstream, etc., it can make a person sick. This usually happens by the “fecal-oral route,” in other words, when someone drinks water or eats food washed in water containing untreated sewage. Restaurant iced tea is a notorious source of coliform bacteria. Our lab students have done studies which have shown that the tap water supplies at local restaurants are OK; homemade, freshly-brewed tea is OK; and freshly-brewed, restaurant iced tea is OK, but restaurant iced tea that has been sitting in a big urn at room temperature for any length of time (as well as one sample of home-brewed tea that was added to a “dirty” pitcher) can have as many as millions of coliform bacteria per 100 mL of tea. In talking with students who work at some of these establishments, a repeating picture begins to emerge. In most cases, the tea is stored at room temperature in large, plastic-lined urns. Whenever the supply in an urn is getting low, the typical procedure is to make more tea and add this new, lukewarm tea to what is already there. In places that are open on a 24-hr basis, this goes on continually. In places that close for a few hours each night, any remaining tea is drained into a plastic pitcher, placed in the refrigerator overnight, then poured back into the urn (which, at most received a cursory rinse the night before) in the morning. Seldomly are the storage urns thoroughly cleaned and sterilized, and students have reported that when they have had to clean one of these urns, the insides are typically coated with slime (= bacterial growth). One lab student told of deciding to clean the urn at work that never got cleaned, and in the process, working a large plug of slime out of the spigot. Typically the restaurants with the cleanest brewed tea have taken the following steps: Many other restaurants have “solved” this problem by switching to instant or other aseptically pre-packaged tea, thereby sacrificing flavor for convenience rather than taking the time to keep equipment clean. Consider that at home, most people typically make a pitcher of tea at a time, keep it refrigerated until use, then thoroughly wash the pitcher before adding a new batch of tea to it. If you want iced tea at a restaurant, order a cup of hot tea and a cup of ice, and make it yourself (maybe? — I’ve heard that ice-machine ice and/or lemon slices may be suspect, too, but we haven’t tested them).
E. coli can also contaminate meat if the animal’s rectum is not carefully removed during the butchering process and fecal material comes into contact with the animal’s carcass. Food workers, anywhere, can spread E. coli if they do not thoroughly wash their hands after defecating/wiping (which may be the source of the iced-tea problems at many fast-food restaurants).
Epidemics of this disease can be prevented by proper sewage handling. Cincinnati, as well as a number of other places, experienced a cholera epidemic in the 1800s. Consider that back then people didn’t know what we now know about bacteria, nor did most people have indoor plumbing. Often, when someone cared for someone else with cholera (changing clothes and bedding following an episode of diarrhea), the caregiver didn’t know to wash his/her hands afterward before eating. They just didn’t know that: nobody washed their hands as much as we do now, and without indoor running water, hand-washing was a lot more bother to do. Also, they didn’t have sewage treatment plants like we do, so typically this sewage was dumped on the ground or in a hole (the outhouse), or into the local water supply. Thus, ingestion of some of the bacteria either from one’s own hands or from drinking the water was a common source of exposure. One main symptom is diarrhea, and most victims die of dehydration. Now, people who do get cholera can recover if hospitalized so they can be given IV fluids to replace those lost by the diarrhea. Travelers to countries without modern sewage treatment facilities are often told to not drink water, eat locally-caught fish, and/or eat fresh vegetables washed in the local water to avoid the possibility of contracting cholera (among other diseases). Usually boiling the water and/or eating vegetables cooked in boiling water are often OK because the boiling kills the cholera bacteria.
When war forces people to flee from their homes to refugee camps, cholera is a major concern. Often, these refugee camps rapidly form on the bank of a lake or stream which is used as a source of drinking water for a large number of people under very crowded and primative conditions. There is neither time, money, nor materials to build a means of sanitary waste disposal, so the lake or river being used as a water supply quickly becomes contaminated. With few, if any, medical supplies available, the disease cannot be controlled and spreads rapidly.
Bubonic Plague:
(bubo = groin, swollen gland) This is also known as Black Death, and is infamous for wiping out about a third of the population of Europe in the Middle Ages (Imagine. . . out of a class of 30 students, what if 10 all died from the same disease? . . . How about ⅓ of the whole student body at school?). Yersinia pestis, the bacterium which causes this disease, is found in wild rodents: rats, mice, squirrels, prairie dogs, and is transmitted by the bite of a flea from an infected animal or from another person by inhaling droplets from coughing. The incubation time is usually 2 to 5 days with abrupt onset. Symptoms include chills, fever, rapid pulse, and low blood pressure. The bacteria invade and multiply in lymph nodes, especially in the groin area. Enlarged lymph nodes, called buboes (bubo = groin, swollen gland) appear with or just after the fever, and the groin lymph nodes are most commonly affected (but others can also be infected). Infected lymph nodes are extremely swollen, tender, and firm; and usually, the overlying skin is reddened. The death rate in untreated victims is about 60%, usually from sepsis (a body-wide bacterial infection), in 3 to 5 days. If the person lives that long, the infected lymph nodes may fester and discharge pus in the second week. Another form of plague involves infection of the lungs instead. One main symptom of this form is coughing, with the sputum thus produced rapidly going from mucus to bloody. Most untreated patients with this form die within 48 hr of onset.
Medieval people made up a graphic little rhyme that is a reenactment (originally for/by adults, not children) of plague that has survived to this day as a nursery rhyme. Some parents, knowing the history of this “game,” question the wisdom of teaching this to their children:

Ring around the rosey,/ Pocket full of posey,/ Ashes, ashes,/ We all fall down!

“Ring Around the Rosy” is about plague. The rosy red rings are the buboes. I’ve heard two possible explanations for the second line. One explanation suggests that the “Pocket full of posy” refers to the custom of wearing small bags of herbs (like onions or garlic) to prevent plague (which, obviously didn’t work so well). Another explanation suggests that this refers to the pus that forms in the pocket-like buboes. “Ashes, ashes, We all fall down” is a reference to the raging fever and the fact that most people died from the plague.
The story of the “Pied Piper of Hamelin” is also about plague. According to this old tale, the German town of Hamelin was overrun by plague-infested rats, which the piper led to their death in the river. The town council then double-crossed him and refused to pay him, so he secretly piped all the children away in the middle of the night and took them to Transylvania. To this day, there is an unexplained population of Germanic people in Transylvania, in the midst of all the Slovakians.

Other Bacteria:

Clostridium sp.:
Two common pathogens in this genus cause botulism and tetanus (the disease). Botulism (botulus = sausage) is a type of food poisoning, and is often found in undercooked meats. The bacteria secrete toxins which are made of proteins which are resistant to digestion by our GI tract, so are absorbed through the intestinal wall, and are toxic to humans. Under adverse conditions, botulism bacteria (and other bacteria) can form spores, a dormant stage that is resistant to dry heat (roasting, broiling), but killed by moist heat (steaming, boiling, etc.). Also, typically microwaving does not provide enough heat for a long enough time to kill these bacteria. These bacteria grow well at body temperature and warm room temperature (summer temperature), thus it is important to beware of slowly-cooling soup with meat in it or left-over turkey stuffing (chill these quickly in the refrigerator, not sitting in the pot on the stove until they “cool”) and egg (especially raw) and/or meat-containing foods at picnics on hot day (deviled eggs containing mayonnaise are especially suspect, but any foods containing mayonnaise may be a problem). In general, vegetables, especially fresh/raw, are OK. Honey can contain small numbers of botulism spores which our bodies can effectively combat, so it’s generally not a concern. However, young babies’ immature immune systems have problems dealing with this small number of bacteria, thus infants under one year old should not be fed honey.
Tetanus (tetano = rigid, tense) is a disease in which all the person’s muscles stiffen and contract due to the presence of a toxin secreted by the bacteria. It’s not the rust on a rusty nail that’s the problem, it’s the possibility of tetanus bacteria living there. Note, by the way, that the term “tetanus” technically refers to the condition of all the muscles being stiffened and contracted, no matter what the cause. Injury of a body part and/or certain drugs (strychnine) can cause tetanus. In this case, the word “tetanus” is used to refer not only to the condition of the muscles, but also to the bacteria and their toxin which, in this case, is the cause of the condition.
(tuberculum = a little knob, swelling) This disease was at a low for a long time, but now is a problem again because of multiple-drug-resistant strains that have evolved due to the overuse of antibiotics. These bacteria live in the lungs and destroy lung tissue.
Hansen’s Disease:
This is a disease, better known by another name, with an ancient history. It’s not very contagious, but ancient and Medieval people didn’t know that, so people with this disease were required to live outside of town and not associate with “normal” people, much the way some AIDS victims have been treated today. We now know that while this bacterium can’t be killed — the disease can be treated but never cured, and victims must take antibiotics “for ever” — a person on antibiotics can lead a normal life and is not contagious. However, because of the historical, unjustified fear of this disease, its name was changed to Hansen’s disease so victims could have a chance at a fairly normal life without discrimination. If you haven’t guessed from this description, the original name of this disease was leprosy. This affects the person’s nerves, so (s)he loses his/her sense of feeling in affected body parts, often resulting in a greater danger of injury to those body parts (imagine not being able to tell when something is too hot to touch, thus not instinctively pulling back your hand). The U. S. had a leprosarium at Carville, Louisiana from 1894 to 1999. Armadillos can carry the leprosy bacterium.
This bacterium is spread by intercourse (it is an STD). The initial symptom is a sore on the genitalia followed later by a serious, general infection. A baby can become blind if (s)he gets syphilis in his/her eyes as (s)he is being born, thus hospitals routinely squirt silver nitrate (AgNO3) in newborns’ eyes, whether their mothers have this infection or not, thereby causing the babies’ eyes to become irritated and puffy (If you have ever worked with this in chemistry lab, you may know that if you get it on your skin, and your skin is subsequently exposed to light, that area of skin will turn black until it wears off.).
Lyme Disease:
This bacterium is spread by the bite of a deer tick, thus is more common around wooded, rural areas. It is named after the town of Lyme, Conn., where it was first observed. There may be some inflammation around the site of the bite, but not always. However, if untreated at that stage, the main symptom is an arthritis-like condition that can last for months.
Copyright © 1997 by J. Stein Carter. All rights reserved.
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