MBI exam 3
Specify the salient differences among the three different staphylococcal skin diseases and toxic shock syndrome.
Abscesses- a pus filled lesion. Furuncle (boil)- can begin as a pimple. Carbuncle- deeper tissue penetration, lateral spread Impetigo- caused by exfoliative toxin, thin walled abscesses, blisters in patches just below skin Scalded skin syndrome- caused by exfoliative toxin, seen in infants, skin becomes red and peels off, high mortality Toxic shock syndrome- fever, diarrhea, sore throat, vomiting, skin peeling on palms and soles, shock, sunburn like rash
Outline the characteristics of the tuberculosis organism, with emphasis on its staining reactions and its diagnosis. Include in your outline the implications of a positive skin test.
Agent of tuberculosis is Mycobacterium tuberculosis (MTB). TB is not gram positive or gram negative. If a gram stain is performed on MTB, it stains very weakly gram positive or not at all. MTB is referred to as acid-fast bacteria because of its impermiability by certain dyes and stains. Despite this, once stained, acid fast bacteria will retain dyes when heated. One test for MTB is the Ziehl Neelsen stain method. This uses a pink dye. Glycolipids in cell wall allows retention of acid fast stain. The diagnosis of TB is a TB skin test, chest X-ray, or acid-fast bacilli in sputum (staining method). Problem with skin test is that the vaccine, BCG, is often given in other countries outside of the US and it causes the skin test to be positive every time.
Identify the importance of Escherichia coli as a pathogenic bacterium. Why is Escherichia coli able to cause such a wide range of diseases
Because there are three strains of it that are toxic, invasive, and pathogenic Enterotoxigenic strains- produces enterotoxin similar to cholera toxin Enteropathogenic strains- cause of infant diarrhea Enteroinvasive strains- invasive. Penetrates
relationship between chickenpox and herpes zoster (shingles)
Chickenpox and herpes zoster are both caused by the same virus, the varicella-zoster virus. shingles cannot develop without having chickenpox during childhood
Write a short paragraph on chickenpox, including communicability, incidence, symptoms, and possible complications.
Communicability- among must communicable Incidence- 12th most reported disease in US Symptoms- early: fever, malaise, headache. Fluid filled vesicles develop after 3 days. Complications- reye's, pneumonia, encephalitis, bacteria infection of skin
Compare and contrast the diseases caused by Streptococcus pyogenes with respect to symptoms, exotoxin production, and immunological complications.
Diseases caused by Streptococcus pyogenes (upper respiratory tract): Group A strep AKA STREPTOCOCCUS PYOGENES: 10-20% of people are carriers but do not have symptoms. Like for example when you stop taking your antibiotics for strep throat after u are feeling better, you are a carrier. GAS is a bacteria, not a disease. It's the thing that causes the disease. It turns to a severe illness when it becomes invasive GAS, like when the bacteria gets into places it shouldn't be, like the blood, muscle, or lungs. M protein- a virulence factor that can be produced by strep. Major virulence factor for group A strep. M protein is a virulence factor that can be produced by certain species of Streptococcus. Viruses, parasites and bacteria are covered in protein and sugar molecules that help them gain entry into a host by counteracting the host's defenses. One such molecule is the M protein produced by certain streptococcal bacteria. CAUSES: Pharyngitis- strep throat- primary disease in pharynx. Transmission- droplets. Incubation- 1-3 days. Symptoms- high fever, swollen tonsils, red pharynx tissue, pus. Mild illness from GAS Scarlet fever: Group A strep + toxin Strep throat with skin rash Due to erythrogenic toxin Capillary wall damage; blood leaking The toxin is only produced by certain strains Antibody to toxin provides immunity to scarlet fever rash (not strep throat) Immune complications of GAS Can happen 1-4 weeks after infection Rheumatic fever- inflammation of blood vessels, permanent scarring of heart valve, eleminate infection early to avoid these complications Glomerulonephritis- inflammation in kidneys, can cause permanent damage Other GAS diseases Skin infection Erysipelas aka St. Anthony's Fire aka Butterfly disease- spreads from wounds and abrasions, well defined skin eruptions Impetigo- vesicles, pustules, crusted Blood infection Septicemia- blood poisoning from surgical or traumatic wounds Puerperal sepsis- childbed fever, infection of uterus following childbirth Severe GAS infections Necrotizing fascitis: flesh-eating bacterium, GAS infected wounds, extensive damage to soft tissue, rapid speed, excavation/amputation to treat Pneumonia- respiratory infection, rapidly fatal, rare
Outline how the treatment might differ for cases of staphylococcal food poisoning, botulism, cholera, salmonellosis, shigellosis, typhoid fever and ulcers?
Food poisoning- resolved without treatment, just hydrate Botulism- antitoxin, antibiotics, but antibiotics are useless for botulism food poisoning because its not an infection. Antibiotics are essential for infant botulism and wound botulism Cholera- antibiotics and fluid therapy, electrolytes Salmonellosis- disease runs its course, can only treat symptoms, fluid therapy maybe Shigellosis- antibiotics, electrolyte therapy, salt tablets, or IV Typhoid fever- antibiotics: resistance due to R factor Ulcers- combination therapy for 7 days, antibiotics and acid reduction
Indicate the clinical symptoms that might be of value in the diagnosis of staphylococcal food poisoning, botulism, salmonellosis, shigellosis, typhoid fever, and cholera.
Food poisoning- restricted to intestine, cramps, nausea, projectile vomiting, prostration (extremely weak), diarrhea, lasts a few hours then rapid recovery Botulism- blurred/double vision, slurred speech, difficulty swallowing and chewing, labored breathing, limbs lose muscle tone- flaccid paralysis, resembles a stroke Salmonellosis aka gastroenteritis or enteritis- explosive onset diarrhea, nausea, vomiting, low-grade fever, cramps, headache, malaise, may last 1 week. Shigellosis- ranging from mild diarrhea to severe dysentery, renal failure, microbes penetrate intestine and produce enterotoxins then water is released from internal lining. If infection is in small intestine, then it's mild diarrhea. Infection in large intestine, then it's fatal dysentery Typhoid fever- first week: invades small intestine, diarrhea or constapation, fever, headache, muscle pains, deep ulcers. Second week: invades blood, infects macrophages, high fever, delirium, red spots on abs, gall bladder infection, liver abcesses, hole in bowels. Third week: improvement Cholera- profuse watery diarrhea, dehydration, sunken eyes, wrinkled, dry, cold skin, electrolyte imbalance, muscular cramps, heart failure, shock mortality if untreated, recovery in hours if treated
Describe the disease caused by hantavirus, including the reservoir, mode of transmission, and differences between infections in the USA (Hantavirus Pulmonary Syndrome) and in Asia (Hemorrhagic Fever with Renal Syndrome).
Hantavirus: carrier- rodents. Transmission- humans infected by inhaling of aerosolized virus in rodent droppings and urine. In USA: Hantavirus Pulmonary Syndrome (HPS)- initially mild and flu-like, capillary leak syndrome- massive fluid accumulation in lungs, 45% mortality. In asia: Hemorrhagic Fever with Renal Syndrome (HFRS)- upper respiratory with kidney involvement. Initially flu like, rash, internal hemorrhaging, kidney failure, 10% mortality, annual outbreak coincides with harvest because farmers disturb rat holes.
Write a paragraph on influenza explaining the characteristics of the virus, symptoms of infection, treatment, immunization, and complications that can develop from the disease.
Influenza is an acute, contagious disease of the upper respiratory tract. There is no such thing as stomach flu. Occurs in pandemics. 3 types of influenza: A- most pandemics, B- less widespread, C- rare. Spikes in envelope serve as antigens: Hemagglutinin (H)- facilitates attachment. Neuraminidase (N)- enzyme that helps move virus thru mucous to cell to attach. Antigenic variation: immune system is always playing catch up; antigenic drift and antigenic shift. Antigenic drift is when the antigen slowly mutates over time. Gradual accumulation of mutations. Antigenic shift is more dramatic. It's when two different flu viruses invade the same cell. Flu virus has a genome composed of 8 different pieces, so when 2 invade, you could have 16 genomes in same cell. Picture in notes. Antibodies produced during a prior infection are ineffective against new strain. Each year the disease changes, which is why there's no universal flu vaccine, you just have to guess kind of. Symptoms- sudden chills, fatigue, headache, pains in chest, back and legs, fever, dry throat, chest is tight. Lasts for 7-10 days because that's how long it takes for the body to make antibodies. Can lead to secondary infections. Treatment: amantadine, tamiflu, relenza. Vaccine- based on predicted strain outbreak for each flu season. Complications: guillain-barre syndrome follows recovery. Immune system attacks nerves, paralysis, coma. Reye's syndrome: in kids during recovery from flu or chickenpox, rising fever, vomiting, glassy eyed, disoriented, liver and brain damage, coma and death possible, linked to aspirin.
Describe the symptoms of the two forms of leprosy. Why are they different? How does this difference affect diagnosis?
Lepromatous leprosy- thickening of skin that obstructs facial features, twisting of limbs, curling of fingers Tuberculoid leprosy- loss of pain sensation, hypopigmented patches Acid fast stain- lepromatous leprosy Lepromin test (similar to tuberculid test, detects T cells)- tuberculoid leprosy
Describe conditions which may lead to the establishment in the body of the following diseases: pneumococcal pneumonia, and rheumatic fever.
Pneumococcal pneumonia and rheumatic fever are caused by Group A strep, streptococcus pyogenes. One has to be infected with group A strep bacteria that lead to immune complications.
Compare the immunization and treatment available for pneumococcal pneumonia and tuberculosis.
Pneumonoccal pneumonia- microbial disease of the bronchial tubes and lungs. Transmission through droplet and contact. high fever, sharp chest pains, difficult breathing, rust colored sputum. Treatment: antibiotics, vaccine for pneumonia uses capsules from 23 strains Tuberculosis- transmission- droplet founded in crowded living conditions. Malaise, fever, weight loss. treatment: combined antibiotics for 6-9 months, antibiotic resistance is increasing. vaccine - BCG strain of M. Bovis only given to should only be considered for children who have a negative TB test and who are continually exposed, and cannot be separated from adults who are untreated for TB. not widely given in united states. With the BCG vaccine, a TB test will always look positive.
Name the different viruses that can be causes of viral gastroenteritis. What are the symptoms of this disease?
Sapovirus Norovirus Adenovirus Rotavirus Astrovirus Symptoms of viral gastroenteritis are explosive onset diarrhea, vomiting, low grade fever, nausea, cramps, headache, malaise
Compare the microorganisms that cause TB and leprosy. Include in the comparison the species that cause each, diagnosis, transmission, and treatment.
TB- mycobacterium tuberculosis, diagnosis TB skin test (acid fast stain test), screening test. Treatment- antibiotics for 6-9 months. Transmission- droplets Leprosy- mycobaterium leprae, diagnosis through acid fast stain or lepromin test. Transmission is hard to tell because incubation period is 3-7 years but suspected droplets. treatment - multi-drug treatment for 3-5 years because of drug-resistance
Compare and contrast the various diseases caused by Clostridium species, and the role that exotoxins play in each.
Tetanus-produces tetanospasmin toxin which is a neurotoxin Gas gangrene- enzyme production damages healthy tissue, gas production further destroys tissue Both caused by spores that invade
Outline the method of transmission for the rabies virus and highlight some of the symptoms of rabies. Explain the precautions that might take for one who has been bitten by a dog believed to be rabid. Compare the older and newer methods for immunization to rabies.
Transmission- injection of skin with fluid from infected animal, often by a bite Symptoms- early: pins and needles at the bite, flu-like symptoms. Later virus travels to brain: anxiety, paranoia, hallucinations, paralysis, saliva dripping from mouth, hydrophobia, inability to swallow and thirst Vaccine: post-exposure prophylaxis: old vaccine- 24 injections of duck embryo in abs. New vaccine- 4 injections of human diploid cell vaccine in muscle. Pre-exposure immunization- for at risk animal workers, 3 injections.
Write a summary of the anthrax bacillus, including its transmission, symptoms, and historical importance.
Transmission- not really from host to host. A disease or large grazing animal that becomes infected when they inhale the spores in the soil while grazing. Bloodstream invasion. Spores released from carcass upon decay. Symptoms- skin anthrax- boils with black crusts, fever, headache, malaise. Gastro- vomiting, loss of appetite, fever, nausea. Pulmonary- shock and death within a day. Memory loss in survivors Historical importance- first microbe to be proven a cause of disease. First grown in pure culture. First to satisfy Koch's postulates. Among first used for immunization
Describe the sequence of events that takes place when tetanus spores are introduced in a puncture wound. Explain how the effects of tetanus toxin can lead to the symptoms of patients who have tetanus.
Transmission: wound entry by spores. One nerve has electric signal to give to another nerve to signal movement of muscle. Tetanus blocks release of neurotransmitters. Tetanus toxin is a neurotoxin and potent at low doses. Symptoms target short neurons first: lockjaw, stiffness of facial and swallowing muscles, then arching of back and rib muscles and seizures in diaphragm.
Compare measles and German measles with respect to virus, symptoms, congenital transfer, and complications.
Virus- rubeola for measles and rubella for german. Rubella is milder. Both cause red rash Symptoms of measles- early symptoms- hacking, coughing, sneezing, red eye, sensitivity to light. Koplik spots- 2 days after onset. Red patches with white grain-like centers. Rash- begins at hairline. Looks like scarlet fever but sore throat Symptoms of german measles- mild. Occasional fever. Variable pink rash similar to measles. Fast recovery but relapse possible Congenital transfer (mother infecting fetus)- german measles- 30% chance of birth defects if contracted in 1st month of pregnancy. Measles- women who have had measles within ten days of delivery can spread it to their fetuses
relationship between mumps and orchitis
orchitis is the most common complication of mumps
relationship between influenza, chickenpox, and reye's syndrome
reye's syndrome develops in children recovering from influenza and chickenpox
