BACTERIA
Helicobacter pylori is a gram negative curved rod that is motile. Its reservoir is in the human stomach. It is present in about half the world’s population. The diseases it causes are gastric and duodenal ulcers which can result in stomach cancer. The main virulence factors include, flagella which allow H. pylori to move away from the acid contents in the stomach as well as penetrate into the mucus lining of the stomach, urease (which helps neutralize acidic pH of the stomach) allowing it to flourish, adhesions, toxins, and LPS resembles human Lewis antigens which means host immune system will be tricked into thinking the bacteria is self. This bacteria works by invading the protective layer of skin in the stomach, this causes the release of toxins. This disease causes inflammation and many symptoms like: acid reflux, vomiting, regurgitation, belching, flatulence, and nausea. Mostly adults are affected by H. pylori but early onset is possible. This is interesting to me because I was diagnosed with GERD at the age of 15 so although rare the H. pylori bacteria had invaded my body! Treatment involves usually a higher strength antacid, this medication works by a proton pump inhibitor, which decreases the amount of acid production in the stomach. Decreasing the acid production allows epithelial cells to heal. Antibiotics are also prescribed in some cases to treat ulcers.
Helicobacter pylori is a gram negative curved rod that is motile. Its reservoir is in the human stomach. It is present in about half the world’s population. The diseases it causes are gastric and duodenal ulcers which can result in stomach cancer. The main virulence factors include, flagella which allow H. pylori to move away from the acid contents in the stomach as well as penetrate into the mucus lining of the stomach, urease (which helps neutralize acidic pH of the stomach) allowing it to flourish, adhesions, toxins, and LPS resembles human Lewis antigens which means host immune system will be tricked into thinking the bacteria is self. This bacteria works by invading the protective layer of skin in the stomach, this causes the release of toxins. This disease causes inflammation and many symptoms like: acid reflux, vomiting, regurgitation, belching, flatulence, and nausea. Mostly adults are affected by H. pylori but early onset is possible. This is interesting to me because I was diagnosed with GERD at the age of 15 so although rare the H. pylori bacteria had invaded my body! Treatment involves usually a higher strength antacid, this medication works by a proton pump inhibitor, which decreases the amount of acid production in the stomach. Decreasing the acid production allows epithelial cells to heal. Antibiotics are also prescribed in some cases to treat ulcers.
Bordetella pertussis is a gram negative coccobacillus, which causes the whopping cough disease. Whooping cough is an acute respiratory disease usually found in adults. It is spread through aerosols or by direct contact with an infected person or a carrier. The initial symptoms are similar to a common cold. As the disease progresses a dry cough develops, excess mucous, and vomiting. Whopping cough is most contagious during the initial stages when people are not aware that they have it, usually by the time one is diagnosed it is too late for antibiotics. There is a vaccine for this disease. This disease works by colonizing respiratory mucosa, then the bacteria binds to ciliated cells, where it multiplies. The prevention of this disease is limited without the vaccine because people that have whopping cough are contagious in the beginning phase when they may only think they have a cold.
Entercoccus faecium are a nonmotile, gram positive cocci bacterium. This bacteria causes wound infections and sepsis in hospitalized patients. This bacterium is hardy and is able to persist in the environment. E. faecium is usually found in the human colon. Today second to S. aureus, E. faecium is a leading cause of nosocomial infections. The infections it causes are urinary tract infections, wound infections, endocarditis, and catheter associated infections. Species of the enterococci are opportunists; they are just waiting for weakening of the host defenses to flourish. The most effective way to prevent spread of this bacteria is to wash hands with disinfectant soap regularly and replacing gloves when need be. This bacterium is resistant to many antibiotics but the correct antibiotic used can be effective.
Legionella pneumophila is a gram negative, aerobic, motile rod. This bacteria causes legionnaires’ disease and ventilator associated pneumonia in hospitals. L. pneumophila reservoirs include biofilms in water sources, including air conditioning cooling towers, amoebae, soil and water. This is a recently new disease discovered although it has probably existed longer. It is usually spread through aerosols into the air that are dispersed from air conditioning systems in large buildings. This introduces the bacteria to the lungs. This is not contracted from human to human which is unusual. This disease is characterized by fever, disorientation, lethargy, and considerable lung damage. Microbiologists found that most of the invading bacteria were found inside phagocytes, growing inside the phagosome or filling the cytoplasm. L. pneumophila requires high levels of cysteine and iron compounds for nutrients. Legionnaires’ disease is treated most commonly with erythromycin and eliminating bacteria from water sources, which is difficult, would be a good preventative method to use.
Listeria Monocytogenes are motile, gram positive rods. L. monocytogenes have the ability to multiply in refrigerator temperatures. It is found in soil, water and decaying vegetations, many animals, and asymptomatic human carriers. L. monocytogenes has the ability to invade host cells, escape from vacuoles, move through cell, and can cross the placenta. This is a food borne infection, it is rare to be fatal in an adult but since it has the ability to pass the placenta it is very dangerous to a fetus. The large outbreaks have been traced to commercially supplied food usually containing milk. L. monocytogenes is uncommon because it has a high ID50 number and must be ingested in high numbers to cause even a mild infection. People taking antacids are at more of a risk because their stomach acid is reduced. It is hard to trace the source of infection because of its long incubation period. To prevent from getting this illness avoid unpasteurized milk, avoid coleslaw and deli meats, and cook meats thoroughly after stored in the refrigerator.
Neisseria gonorrhea is a gram negative non motile diplococci. It causes gonorrhea disease in humans. Gonorrhea is a sexually transmitted disease that is characterized by inflammation and purulent discharge. Gonorrhea though on the decline is still being transmitted there are about 400,000 cases a year reported to the CDC. N. gonorrhea does not have a vaccine and scientists don’t see one in the near future due to its ability to change surface antigens. This makes it hard for the host immune system to create a successful antibody, also it has the ability to make itself look like host tissue, making it hard for the immune system to recognize it in the first place. This disease tends to go untreated because people don’t know they are infected this puts them at risk for ectopic pregnancy and infertility. Gonorrhea can also be transferred to infants when passing the birth canal. This brings the risk of blindness to infant if the infection gets into the infants eyes, this can be treated through antibiotic eye drops. Treatment for this disease is antibiotics although which antibiotics used is changing due to its ability to become resistant. Prevention of this disease is protected sex, abstinence, and awareness, get checked!
Chlamydia trachomatis is an intracellular pathogen that has a gram negative type cell wall but with no peptidoglycan. This bacterium causes the disease Chlamydia. Chlamydia is a sexually transmitted disease. It is the most common of sexually transmitted diseases when it is transmitted it infects the urinary and reproductive organs. Symptoms are painful urination, discharge, and reactive arthritis in men, women are usually asymptomatic, and infants usually render conjunctivitis, pneumonia, trachoma. Chlamydia can cause ectopic pregnancy and infertility in women. Although Chlamydia is asymptomatic in women they are the most seriously effected. Treatment includes antibiotics and the earlier the intervention the better off you are. Prevention includes abstaining from sex or wearing protection.
Yersinia pestis is the cause of the bubonic plague this is a disease that rendered awful symptoms and had a high fatality rate. Yersiniae are small gram negative coccobacilli and nonmotile. Inflamed lymph nodes usually in the groin and thighs that fill with puss are a dead give away to the disease, they are called buboes, hence the name bubonic plague. The buboes swell until they are approximately the size of a chicken egg. Blood vessels then break, causing internal bleeding. The blood then dries under the skin and gives the buboes the characteristic black color. It had a few outbreaks throughout history and was deemed the”black death”. It is transmitted through a vector usually from a flea on a brown rat that has the disease. It is spread from human to human once it has entered the infected person’s respiratory tract through droplets produced from the lungs. Once someone is infected with the disease if they survive they are immune to Yersinia pestis and will not contract it again.
Neisseria meningitidis is a nonmotile, is a dipplococci, gram negative bacteria. It causes the disease epidemic meningitis that infects humans. N. meningitidis enters the bloodstream and infects the membranes that surround and protect the brain. This causes inflammation that can disrupt the blood-brain barrier. The increased spinal fluid increases pressure on the brain. This is why meningitis is fatal if not treated early enough with effective antibiotics. This disease is not common in most parts of the world. The first signs of meningitis are a fever, stiff neck, a bad headache, or a rash. Treatments include antibiotics and a vaccine. Prevention is if there is an outbreak, avoid congested small places, it is normally spread from person to person through respiratory droplets.
Pseudomonas aeruginosa are gram negative motile rods its colonies have a distinctive blue green color. It is found in soil everywhere and causes disease to humans and plants. Not all Pseudomonas are disease causing. P. aeruginosa is transmitted through vehicles such as: water, soil, and on plants. P. aeruginosa is an opportunistic pathogen that is resistant to most antibiotics most likely due to the many efflux pumps it has. It is also known for its ability to form biofilms but this isn’t really determined as increasing its ability to cause disease. P. aeruginosa is known for its ability to infect burn patients and cause lung infections in cystic fibrosis patients. It is the main cause of death in both of these types of patients if the initial cause itself doesn’t kill them. P. aeruginosa has many factors of virulence some are: adhesions, LPS, toxins, and biofilm formation. There is no vaccine available for this pathogen. The best way to prevent infection of P. aeruginosa is through hygiene.
Staphylococci are gram positive cocci that are prevalent in human diseases. From the Staphlococci family Stahpylococcus aureus is the leading cause of disease. The most common reservoirs on humans are the nose and skin. S. aureus is nonmotile and has golden colored colonies that grow in clusters. Most diseases caused by S. aureus originate when the bacteria take advantage of breaches in skin to enter the bloodstream. Interestingly, S. aureus was considered to be more fatal in World War II than weapons. A large factor in preventing this was the introduction of antibiotics to the battlefield. S. aureus was later found to be responsible for many diseases, endocarditis, osetomyelitis, and central nervous system infections such as, brain abscesses, and pneumonia just to name a few. S. aureus is coagulase positive meaning that it causes blood to clump this is a distinguishing factor used to differentiate S. aureus from other staphylococci. A cause of its existence is its ability to live for long periods of time outside the human body and that it has many virulence factors giving it the ability to evade the host protection mechanisms. Prevention from contracting S. aureus is habitual hand washing, disinfectants, and reduced length of catheter use.
Streptococcus pyogenes is a gram positive, nonmotile bacterium found in the mouth and throat of the human body. It can cause a number of infections ranging from wound infections to pneumonia and post partum maternal infections. S. pyogenes grows best under anaerobic conditions. It colonizes the mouth, throat, and upper respiratory tract. The infections it causes are strep throat, heart disease, scarlet fever, impetigo, cellulitis, toxic shock-like syndrome, wound infections, and bacterima. In the 1700 and 1800s S. pyogenes caused many maternal deaths because it gave rise to puerperal fever, where bacteria in the vaginal tract infected the uterus and the infection would quickly turn systemic. Also During wartime S. pyogenes caused wound infections one in particular sterptococoocal gangrene which destroyed large area of skin and caused death due to septic shock once the bacteria entered the bloodstream. Those are just to name a few diseases this one disease can and has caused. Today it’s most worrisome to those with surgical wounds or indwelling catheters. This bacterium is treated with antibiotics and is susceptible to most.
Vibrio cholerae is a motile, gram negative, curved rod. There are several strains and many do not cause disease. The disease caused by V. chloerae is called cholera, it infects humans. There have been major pandemics throughout history. It is contracted by drinking or eating food cleaned with water that has been contaminated with human feces. It has the ability to survive in fresh water and salty water. Once ingested and in the small intestine V. cholerae attaches to mucosal cells and produces an exotoxin, cholerae toxin, that acts on the intestinal mucous. This toxin works by setting off the balance of flow of ions in and out of tissue resulting in diarrhea and electrolyte imbalance. The disease is most dangerous if it causes lots of water loss, because it will cause the circulatory system to fail and result in death. The good thing about this disease is that when it causes this washout of the body it is included in the loss. This is the most effect form of treatment, letting it run its course while keeping hydrated. Once recovered a person usually gains long term immunity to V. cholerae. There is no successful vaccine for this disease. To prevent getting this disease have a clean water supply and effective sewage treatment.
FUNGI
Aspergillus fumigatus causes a disease called aspergillosis by producing a large number of spores. A. fumigatus is found everywhere in the environment and is hard to avoid. Normally this fungus would be no concern to a healthy individual, but to a person whose immune system is compromised this fungus can cause asperillosis. The route of transmission of this disease is inhalation. If you are considered compromised it is best to stay away from dusty areas. It infects the lungs, inner ears, and sinuses. The symptoms are wheezing, coughing, and sometimes fever. This is caught by chest xrays, tissue samples, and respiratory secretions. If diagnosed it should be treated immediately the usual form of treatment is voriconazole. This is a good pathogenic disease to know about because it is very prevalent, it is found in most environments and hard to avoid.
Histoplasma capsulatum is a pathogenic fungus that is found in the soil it causes the disease histoplasmosis. H. capsulatum grows better with the help of bird and bat feces, so places that these animals reside are common sites that this disease is contracted. This disease is commonly contracted through the respiratory tract; as a result the lungs are the most common site of the infection. This disease is not contracted from person to person it is contracted to someone exposed to the aerosols from soil that has been disturbed. This disease though can cause issues in the liver, heart, and central nervous system as well usually in the more severe cases. This disease prevalent for many years was often mistaken for tuberculosis because the symptoms are similar. The symptoms include, feeling sick, fever, chest pains, and a dry or nonproductive cough. Histoplasmosis has about a 10 day period after being infected before symptoms arise. This disease should not be treated with antibiotics though because that would kill all the competing bacterium allowing the fungus to flourish an antifungal medication would be much more effective, although most cases should resolve themselves.
PROTOZOA
Cryptosporidium parvum is a parasite that causes the disease cryptosporidiosis which results in severe diarrhea, weight loss, and abdominal pain. Crypto is found in the small intestines. It infects humans and animals through drinking water that has been contaminated with feces (human or animal) that has been exposed to the parasite. It is most harmful to those who are immune compromised. This parasite is very hardy and can live for long periods of time without a host and in many environments; it is not a picky parasite! In a healthy individual cryptosporidiosis will resolve on it’s on in a few weeks. C. parvum is killed by heat and freezing so if you chose to eat things that are heated of frozen you will be fine, this is probably why its main facilitator in infection is through water it can also be transmitted from person to person and children are at risk in the daycare setting because there are many germs being passed around. C. parvum is more susceptible to temperature than it is to disinfectants, which scary enough, it is pretty resistant to disinfectants.
HELMINTHS
Wuchereria bancrofti is a parasitic worm that causes the disease we know as elephantiasis also known as in its early stages, lymphatic filariasis. It usually affects the lower extremities but W. bancrofti can affect the upper region as well. This disease is transmitted from mosquitoes; the worm is inserted in the host while the mosquito feeds on our blood injecting the worm into our bloodstream. This causes the lymph nodes to swell, discolor, and thicken the skin. The swelling is caused by the lack of lymph fluid being able to flow. This is a slow growing disease and most people are asymptomatic. You can be tested for this disease by a blood test. If you test positive for W. bancrofti there is a drug treatment. You must be diagnosed though before taking the medicine because it has many side effects and if not treating the worm its side affects are worse. Although this disease isn’t common in our area it is still good to know about because then we can protect ourselves when on vacation. Ways to protect yourself would be nets and bug spray! Stay away from the mosquitoes!
