Final Flashcards
- The cell of gram-positive bacteria may contribute to the develpment of septic shock..*
- identify the component which is most associated with the induction of septic shock.*
Teichoic Acid
Teichoic acid is any of a class of strongly acidic polymers found in the cell walls*, *capsules, and membranes of all gram-positive bacteria and containing residues of the phosphates of glycerol and adonitol.
It is one of two types of polymers* present in *gram-positive bacteria, especially in the cell walls.
This acid is formed through the joining of either glycerol phosphate or ribitol phosphate groups linked together with phosphodiester bonds.
19 year old woman comes to your office after being bitten by a bat on the ear while camping in a primative shelter. She is unable to produce a vaccination record. On physical examination, she is afibrile and appears well. Where are two small puncture marks on the pinna of her left ear. what is an appropriate vaccination strategy in this context?
a. Intravenous ribavirin
b. No vaccination
c. Rabies immunoglobulins
d. Rabies inactivated virus vaccine
e. Rabies inactivated virus vaccine plus immunoglobulins
E) Rabies inactivated virus vaccine
plus
immunoglobulins
In recent years, rabies virus has been most frequently transmitted by bats in the United States. Usually a bite is noted but not always. Therefore, patients who have unexpected, unmonitored (i.e., while they are asleep) close contact with bats should be told to seek medical attention and likely vaccination. A bite is a clear indication for the most effective immunization strategy involving both active (inactivated virus vaccine) and passive (human rabies immunoglobulins) immune activation unless the offending bat is captured and found to be rabies negative with further testing. The vaccination schedule for nonimmunes is intensive, with doses at 0, 3, 7, 14, and 28 days. Although there has been at least one report of successful antiviral treatment of rabies, there is no indication for prophylactic antiviral therapy.
Define
Capsular protein
The bacterial capsule is a large structure of many bacteria. It is a polysaccharide layer that lies outside the cell envelope, and is thus deemed part of the outer envelope of a bacterial cell. It is a well-organized layer, not easily washed off, and it can be the cause of various diseases.
The capsule—which can be found in both gram negative and gram-positive bacteria—is different from the second lipid membrane – bacterial outer membrane, which contains lipopolysaccharides and lipoproteins and is found only in gram-negative bacteria
Most bacterial capsules are composed of polysaccharide, but some species use other materials, such as poly-D-glutamic acidin Bacillus anthracis.
The capsule is considered a virulence factor because it enhances the ability of bacteria to cause disease (e.g. prevents phagocytosis). The capsule can protect cells from engulfment by eukaryotic cells, such as macrophages.
A capsule-specific antibody may be required for phagocytosis to occur
define
endotoxin
A poisonous lipopolysaccharide formed in the cell wall of a GRAM-NEGATIVE bacterium by means of which the organism causes its damage to the host.
Bacterial endotoxin, lipid A
A heat-stable lipopolysaccharide on the outer coat of gram-negative bacteria–eg, those causing cholera , meningitis , pneumonia, plague, whooping cough, et al Clinical Leukopenia, thrombocytopenia, fever, chills, hemorrhagic shock, dec resistance to infectioe
define
Peptidoglycan
a polymer that is composed of polysaccharide and peptide chains and is found especially in bacterial cell walls
— called also mucopeptide, murein-
serves a structural role in the bacterial cell wall, giving structural strength, as well as counteracting the osmotic pressure of the cytoplasm. Peptidoglycan is also involved in binary fission during bacterial cell reproduction.
define
Phospholipids
any of various phosphorus-containing complex lipids (such as lecithins and phosphatidylethanolamines) that are derived from glycerol and are major constituents of the membranes of cells and intracellular organelles and vesicles
NOTE: Phospholipids typically consist of a hydrophilic polar phosphate head and a hydrophobic tail of two fatty acids. In aqueous environments, phospholipids typically form semipermeable bilayers in which the hydrophilic heads point outward and the hydrophobic tails point inward toward each other.
Name common cause of urethritis
in
Men
- Mycoplasma genitalium
- Neisserial gonorrhea
- Trichomonal vaginalis
- ureaplasma urealyticum
- Chlamydia trichomonas
what type of bacteria that cause either
a type of respiratory or a form of sexually transmitted illness?
Chlamydia includes certain species of bacteria that cause either a type of respiratory or a form of sexually transmitted illness in people depending on what species is involved.
The infections are caused by two different species of bacteria, Chlamydia trachomatis and Chlamydia pneumoniae that live inside the cells of the host.
define
Gardnerella vaginalis
G. vaginalis is associated with bacterial vaginosis, which may be asymptomatic, or may have symptoms including vaginal discharge, vaginal irritation, and a “fish-like” odor.
In the amine whiff test, 10% KOH is added to the discharge; a positive result is indicated if a fishy smell is produced. This and other tests can be used to distinguish between vaginal symptoms related to G. vaginalis and those caused by other organisms, such as Trichomonas and Candida albicans
G. vaginalis produces a pore-forming toxin, vaginolysin, which affects only human cells
All of the following individuals receiving tuberculin skin purified protein derivative (PPD) reactions should be treated for latent tuberculosis EXCEPT:
a. A 23-year-old injection drug user who is HIV negative has a 12-mm PPD reaction.
b. A 38-year-old fourth grade teacher has a 7-mm PPD reaction and no known exposures to active tuberculosis. She has never been tested with a PPD previously.
c. A 43-year-old individual in the Peace Corps working in sub-Saharan Africa has a 10-mm PPD reaction. Eighteen months ago, the PPD reaction was 3 mm.
d. A 55-year-old man who is HIV positive has a negative PPD result. His partner was recently diagnosed with cavitary tuberculosis.
e. A 72-year-old man who is receiving chemotherapy for non-Hodgkin’s lymphoma has a 16-mm PPD reaction.
B) A 38-year-old fourth grade teacher has a 7-mm PPD reaction and no known exposures to active tuberculosis. She has never been tested with a PPD previously.
The aim of treatment of latent tuberculosis is to prevent development of active disease, and the tuberculin skin test (purified protein derivative [PPD]) is the most common means of identifying cases of latent tuberculosis in high-risk groups. To perform a tuberculin skin test, 5 tuberculin units of PPD are placed subcutaneously in the forearm. The degree of induration is determined after 48 to 72 hours. Erythema only does not count as a positive reaction to the PPD. The size of the reaction to the tuberculin skin test determines whether individuals should receive treatment for latent tuberculosis. In general, individuals in low-risk groups should not be tested. However, if tested, a reaction larger than 15 mm is required to be considered as positive. School teachers are considered low-risk individuals. Thus, the reaction of 7 mm is not a positive result, and treatment is not required. A size of 10 mm or larger is considered positive in individuals who have been infected within 2 years or those with high-risk medical conditions. The individual working in an area where tuberculosis is endemic has tested newly positive by skin testing and should be treated as a newly infected individual. High-risk medical conditions for which treatment of latent tuberculosis is recommended include diabetes mellitus, injection drug use, end-stage renal disease, rapid weight loss, and hematologic disorders. PPD reactions 5 mm or larger are considered positive for latent tuberculosis in individuals with fibrotic lesions on chest radiographs, those with close contact with an infected person, and those with HIV or who are otherwise immunosuppressed. There are two situations in which treatment for latent tuberculosis is recommended regardless of the results on skin testing. First, infants and children who have had close contact with an actively infected person should be treated. After 2 months of therapy, a skin test should be performed. Treatment can be discontinued if the skin test result remains negative at that time. Also, individuals who are HIV positive and have had close contact with an infected person should be treated regardless of their skin test results.
One goal of immunization programs is to eliminate a specific disease. In 2010, indigenous transmission of which of the following diseases had been eliminated in the United States?
a. Diphtheria
b. Mumps
c. Pertussis
d. Varicella
e. None of the above
a. Diphtheria
Immunization programs have the goals to control, eliminate, and eradicate disease. Disease control refers to decreases the impact of a specific illness on both health-related and societal outcomes. Examples of vaccinations that have lead to improved control of disease include the pneumococcal and influenza vaccines. Elimination can have two meanings. The first definition is to have zero cases in a defined geographic area. A second meaning is to reduce or eliminate the indigenous sustained transmission of an infection in a specific geographic area. In 2010, vaccine programs had eliminated measles, rubella, poliomyelitis, and diphtheria in the United States, although increasing numbers of cases of measles have been reported is some parts of the United States because of incomplete vaccination in children. Disease eradication is the most difficult goal to achieve. A disease can be considered eradicated when its elimination can be sustained without ongoing interventions. The only disease that has been globally eradicated at this point is smallpox. Poliomyelitis has been eradicated in most of the world although Afghanistan, Pakistan, India, and Nigeria continue to have ongoing transmission of the disease.
A 63-year-old man has chronic obstructive pulmonary disease and presents to your office for routine follow-up. He has no complaints currently and feels well. He is being managed with tiotropium 18 μg once daily with albuterol metered-dose inhaler as needed. His most recent forced expiratory volume in 1 second (FEV1) was 55% predicted, and he is not on oxygen. He has received one dose of pneumococcal vaccine 5 years previously. He is asking if he should receive another dose of pneumococcal vaccine. According to the guidelines of the Centers for Disease Control and Prevention, what is your recommendation?
a. He does not require further vaccination unless his FEV1 drops below 50% predicted.
b. He does not require further vaccination until he reaches age 65 years.
c. He should be revaccinated today.
d. He should be revaccinated 10 years after his initial vaccine.
e. No further vaccination is recommended because a single dose is all that is required.
b. He does not require further vaccination until he reaches age 65 years.
Pneumococcal vaccination has been recommended for all individuals at any age with a variety of chronic medical conditions, including chronic respiratory disease, chronic heart disease, chronic liver failure, diabetes mellitus, asplenia, and chronic kidney disease. Determining when to revaccinate individuals has been somewhat controversial. The current recommendations are to revaccinate individuals ages 19 to 64 5 years after the initial vaccine if they have chronic renal failure or nephrotic syndrome, asplenia, or other immunocompromising conditions. All other individuals should receive a one-time revaccination at age 65 years and older if they were vaccinated 5 or more years previously and younger than 65 years old at the time of original vaccination.
In which of the following patients is it appropriate to administer the vaccination against herpes zoster?
a. A 35-year-old woman who has never had varicella-zoster infection who is 12 weeks pregnant with her first child
b. A 54-year-old man who has never had varicella-zoster infection and is otherwise healthy
c. A 62-year-old man with HIV on antiretroviral therapy with a CD4+ lymphocyte count of 450/μL
d. A 64-year-old woman with dermatomyositis-associated interstitial lung disease treated with prednisone 20 mg daily and azathioprine 150 mg daily
e. A 66-year-old woman who was recently diagnosed with non-Hodgkin lymphoma
c. A 62-year-old man with HIV on antiretroviral therapy with a CD4+ lymphocyte count of 450/μL
The varicella-zoster vaccine is a live virus vaccine that was recently introduced for prevention of shingles in older adults. The current recommendation is all adults older than 60 years be offered the zoster vaccine regardless of whether they report a childhood history of chickenpox. As this is a live virus vaccine, it cannot be administered to anyone who has severe immunodeficiency. Specific recommendations for whom the zoster vaccine is contraindicated include:
- Pregnancy
- Anyone younger than 60 years
- Patients with leukemia, lymphoma, or other malignant neoplasms affecting the bone marrow. If a patient is in remission and has not received chemotherapy or radiation therapy within 3 months, the vaccine can be given.
- Individuals with AIDS or HIV with a CD4+ count <200/μL or ≤15% peripheral lymphocytes
- Individuals taking immunosuppressive therapy equivalent to prednisone ≥20 mg/day, methotrexate 0.4 mg/kg/wk, or azathioprine <3 mg/kg/day
- Anyone with suspected cellular immunodeficiency (e.g., hypogammaglobulinemia)
- Individuals receiving a hematopoietic stem cell transplant
- Individuals receiving recombinant human immune mediators or modulators, especially antitumor necrosis factor agents
A 39-year-old woman received a liver transplant 2 years ago and is maintained on prednisone, 5 mg, and cyclosporine, 8 mg/kg per day. She has had two episodes of rejection since transplant, as well an episode of cytomegalovirus syndrome and Nocardia pneumonia. She intends on taking a 2-week gorilla-watching trip to Rwanda and seeks your advice regarding her health while abroad. Which of the following potential interventions is strictly contraindicated?
a. Malaria prophylaxis
b. Meningococcal vaccine
c. Rabies vaccine
d. Typhoid purified polysaccharide vaccine
e. Yellow Fever Vaccine
e. Yellow Fever Vaccine
Live-attenuated viruses are generally contraindicated as vaccines for immunocompromised hosts for fear of vaccine-induced disease. The most cited example of this is smallpox vaccine resulting in disseminated vaccinia infection. However, yellow fever vaccine is another example of a live virus vaccine. The other examples listed in this example are inactivated organisms (rabies, IM typhoid) or polysaccharide (meningococcal) and are therefore noninfectious. Oral typhoid vaccine is a live-attenuated strain, so the IM form is likely preferable in this host. Malaria prophylaxis currently involves chemoprophylaxis rather than vaccination. Although safe from an infectious standpoint, potential interactions with cyclosporine should be monitored.
Which of the following diagnostic features characterizes
bacterial vaginosis?
A) Vaginal Fluid pH+4.5, clue cells and profouse mised microbiota on microscopic examination
The diagnosis of BV is generally made by using the Amsel criteria : This encompasses fulfilling three of the following four criteria:
(i) presence of abnormal vaginal discharge,
(ii) elevated vaginal pH (>4.5),
(iii) positive amine odor test,
(iv) presence of clue cells on vaginal Gram smear.
Which of the following immunizations is required for entry into many countries in sub-Saharan Africa?
a. Hepatitis A
b. Cholera
c. Meningococcus
d. Typhoid fever
e. Yellow fever
e. Yellow fever
When traveling abroad, it is important to plan ahead and consider the potential infectious agents to which one might be exposed. The Centers for Disease Control and Prevention and the World Health Organization publish guidelines for recommended vaccinations before travel to countries around the world. Before travel, it is certainly recommended that an individual be up to date on all routine vaccinations, including measles, diphtheria, and polio. Influenza is perhaps the most common preventable illness in travelers, and the influenza vaccine should be administered per routine guidelines. There are, however, very few required vaccinations in most countries. Yellow fever is one exception, and proof of vaccination is required by many countries in sub-Saharan Africa and equatorial South America. This is especially important for individuals traveling from areas where yellow fever is endemic or epidemic. The only other required vaccinations are meningococcal meningitis and influenza vaccination to travel in Saudi Arabia during the Hajj.
Deficits in the coplement memebrane attack complement (C5-8) are associated with infections of what variety?
Neisseria mengitiditis
or
Nesseria Gonorrhea
ONLY 2 colonize human mucosal surfaces- nesseria have thin cell wall and little to no glycocalyx.
Glycocalyx also known as the pericellular matrix, is a glycoprotein and glycolipid covering that surrounds the cell membranes of some bacteria, epithelia, and other cells
define
dimorphic Fungi
occurring in or representing two distinct forms
Dimorphic fungi are fungi that can exist in the form of both mold and yeast
Which of the following fungi is considered Dimorphic?
a. Apergillus Fumigatus
b. candida albicans
c. cryptococcus neoformans
d. histoplasma
Histoplasma
Name
Dimorphic Fungi
which also cause what type of infections?
Systemic infections
define
Herpangina
called mouth blisters, is a painful mouth infection caused by coxsackieviruses.
Usually, herpangina is produced by one particular strain of coxsackie virus A (and the term “herpangina virus” refers to coxsackievirus A) but it can also be caused by coxsackievirus B or echoviruses.
Most cases of herpangina occur in the summer, affecting mostly children. However, it occasionally occurs in adolescents and adults
Match the following Viruses with their primary clinical manifistations:
a. Adenovirus
b. Coronavirus
c. human respiratory syncytial virus
d. parainfluenza
e. rhinovirus
a. are common viruses that cause a variety of illnesses in humans. Most commonly, they cause respiratory tract infections or conjunctivitis (inflammation of the lining of the eyes)
NOT Herpangina
b. severe acute respiratory syndrome
c. bronchiolitis in infants and young children
d. croup
e. common cold
A 48-year-old woman is traveling to Haiti with a humanitarian aid group. What is the recommended prophylaxis against malaria for this patient?
a. Atovaquone–proguanil
b. Chloroquine
c. Doxycycline
d. Mefloquine
e. Any of the above can be used
e. Any of the above can be used
Malaria remains endemic in many parts of the world, and an estimated 30,000 travelers from the United States and Europe are infected with malaria during travel yearly. The areas of highest risk are in sub-Saharan Africa and Oceania with the lowest risk in South and Central America, including Haiti and the Dominican Republic. Chloroquine resistance is growing throughout the world and is especially notable in parts of South America, Africa, and Southeast Asia. However, in Haiti, the incidence of chloroquine resistant malaria is low. For a traveler to Haiti, the Centers for Disease Control and Prevention states that travelers have a choice of chloroquine, doxycycline, atovaquone–proguanil, or mefloquine. In addition, travelers should be cautioned to use appropriate techniques for malarial prevention, including protective clothing, DEET-containing insect repellants, permethrin-impregnated bednets, and screened sleeping accommodations, if possible.
name all statements regarding
Norwalk virus gastroenteritis
that are true.
(5 statements)
- fever is common
- incubation period is typically 12-48 hours
- infection is common worldwide
- transmission is typically fecal-oral
- it is major cause of nonbacterial diarrhea in infants
A 46-year-old man wishes to travel to Kenya for a 2-week vacation. He is HIV positive and is taking antiretroviral therapy. His last CD4+ count was 625/μL and viral load was undetectable. His nadir CD4+ count was 250/μL. He has never had an AIDS-defining illness. In addition to HIV, he has a history of hypertension and is known to have proteinuria caused by to HIV-associated nephropathy. What is your recommendation to this patient regarding his travel plans?
a. He should not receive the live measles vaccine before travel.
b. He should receive the yellow fever vaccine before travel.
c. He will be required to show proof of HIV testing upon entry into the country.
d. His likelihood of response to the influenza vaccine would be less than 50%.
e. With a CD4+ count greater than 500/μL, he is at no greater risk during travel than persons without HIV.
e. With a CD4+ count greater than 500/μL, he is at no greater risk during travel than persons without HIV.
Individuals with HIV are generally considered at high risk of infectious complications when traveling abroad. However, individuals who have no symptoms and a CD4+ count greater than 500/μL appear to be at no greater risk than individuals without HIV infection. Before travel, it is important to research the travel requirements for the specific country of travel. Many countries routinely deny entry for HIV-positive individuals for prolonged stays, and proof of HIV testing is required in many countries for stays longer than 3 months. Consular offices should be contacted before travel to determine if any special documentation is required. HIV-infected travelers should have all routine immunizations before travel, including influenza and pneumococcal vaccinations. The response rate to influenza in an asymptomatic HIV-positive person is greater than 80%. Generally, live-attenuated viruses are not given to HIV-infected individuals. However, because measles can be lethal in those with HIV, this vaccine is recommended unless the CD4+ count is less than 200/μL, and the expected response rate would be between 50% and 100%. In contrast, the live yellow fever vaccine is not given to HIV-infected travelers, and individuals with CD4+ counts below 200/μL should be discouraged from traveling to countries with endemic yellow fever. Some countries in sub-Saharan Africa require yellow fever vaccination. However, because this patient is traveling from a low-risk area, a medical waiver would likely be issued.
All of the following statements regarding interferon-gamma release assays for the diagnosis of latent tuberculosis are true EXCEPT:
a. There is no booster phenomenon.
b. hey are more specific than tuberculin skin testing.
c. They have a higher sensitivity than tuberculin skin testing in high HIV-burden areas.
d. They have less cross reactivity with BCG and nontuberculous mycobacteria than tuberculin skin testing.
e. They may be used to screen for latent tuberculosis in adults working in low prevalence U.S. settings.
c. They have a higher sensitivity than tuberculin skin testing in high HIV-burden areas.
T-lymphocyte release of interferon-gamma in response to highly specific tuberculosis antigen stimulation is the basis for the commercially available interferon-gamma release assays (IGRAs). IGRAs are more specific than tuberculin skin testing caused by less cross-reactivity with non-mTB organisms, including Bacillus Calmette-Guérin and nontuberculous mycobacteria. The absolute sensitivity of IGRAs is not clearly known because of the difficulty in establishing a gold standard, but most studies demonstrate superior performance in detecting latent tuberculosis in low-incidence settings. They also are more user friendly because there is no administration expertise, interpretation is less subjective, and results do not require a second visit. The results are far less clear in settings of high tuberculosis or HIV burden. The tuberculin skin testing booster phenomenon, a spurious conversion caused by serial testing, does not occur with IGRAs; however, a tuberculin skin test may cause a false-positive IGRA result. In the United States, IGRA is preferred for most persons older than 5 years of age being screened for latent tuberculosis
a 25 year old woman presents with 2 days of urinary frequency, urgency and pelvic discomfort. She has no pain in her vulva on urination. She has no other medical problems and does not have fevers. she is sexually active. a microscopic examinationof her urine shows pyuria but no pathogens. after 24 hours, her urine curlture does not grow any pathogens which test will likely confirm her diagnosis?
Nucleic acid amplification test of urine for
Chlamydia trachomatis
- Enteric pathogens can produce diarrheal illness thuogh a variety of mechanisms that lead to specific clinical characteristis. All of the following characterisics of diarrhea caused by Vibrio Cholera Except?*
a. Disease localized to the proximal small intestine
b. fecal leukocytes
c. non-bloody diarrhea
d. toxin production
e. watery diarrhea
b. fecal leukocytes
20 year old woman is 36 weeks pregnant and presents for her first evaluation. she is diagnosed woth chlamydia trachomatis infection of the cervix Upon delivery, for what complication is her infant most at risk?
Conjunctivitis
Pink eye (conjunctivitis) is an inflammation or infection of the transparent membrane (conjunctiva) that lines your eyelid and covers the white part of your eyeball. When small blood vessels in the conjunctiva become inflamed, they’re more visible. This is what causes the whites of your eyes to appear reddish or pink.Pink eye is commonly caused by a bacterial or viral infection, an allergic reaction, or — in babies — an incompletely opened tear duct
What is the common manifestation of
Clostridium difficle infection?
Fever
non-bloody diarrhea
adynamic ileus
recurrence after therapy
(all of the above)
define
Clostridium difficile
is a germ (bacterium) that causes severe diarrhea and colitis (an inflammation of the colon).
About 1 in 6 patients who get C. diff will get it again in the subsequent 2-8 weeks.
name Respiratory viruses that are a cause of the common cold syndrome in children or adults.
Except …
- Adenoviruses
- cononaviruses
- Human respiratory syncitial viruses
- Rhinovirus
EXCEPT: Enteroviruses
define
Enterovirus
a genus of positive-sense single-stranded RNA viruses
Enteroviruses are named by their transmission-route through the intestine (enteric meaning intestinal)
On the basis of their pathogenesis in humans and animals, the enteroviruses were originally classified into four groups, polioviruses, Coxsackie A viruses (CA), Coxsackie B viruses (CB), and echoviruses
- all of the following statements regarding intestinal disease caused by strain of Shiga toxin-producing and enterohemorrhagic E. coli are true except?*
- a. antibiotic therapy lessens the risk of developing hemolytic uremic syndrome*
- b. groud beef is the most common source of contamination*
c. gross bloody diarrhea without fever is themost comon clinical manifiestation
d. infectionis more common in industrialized than developing countries
e. 0157:H7 is the most common stereotype
a. antibiotic therapy lessens the risk of developing hemolytic uremic syndrome
a 46 year old woman travels to a rular area fo Guatemala. three days after arriveal, she develops watery diarrhea with sever abdominal cramps. she resport 2 unformed stools daily for the past 2 days. she has noticed no blood in the stool and has not experienced fever. what is the most likley cause of the patients illness?
a. campylobacteri jejuni
b. ETEC
c. norovirus
d. shigella sppl
e. EHEC
b. ETEC
define
campylobacteri jejuni
Campylobacter jejuniinfection causes cramping, diarrhea, abdominal pain and fever within 2 to 5 days after a person has been exposed to the organism.
Campylobacter infection occurs in the small intestine from bacteria called Campylobacter jejuni.
jejuni is commonly associated with poultry, and is also commonly found in animal feces. Campylobacter is a helical-shaped, non-spore-forming, Gram-negative, microaerophilic, nonfermenting motile bacterium with a single flagellum at one or both poles,[5] which are also oxidase-positive and grow optimally at 37 to 42 °C.
- Enterotoxigenic Escherichia coli (E. coli),*
- or*
- ETEC*
Escherichia coli is a bacterium that normally lives in the intestines of humans and other animals. Most types of E. coli are harmless, but some can cause disease. Disease-causing E. coli are grouped according to the different ways by which they cause illness. Enterotoxigenic Escherichia coli, or ETEC, is the name given to a group of E. coli that produce special toxins which stimulate the lining of the intestines causing them to secrete excessive fluid, thus producing diarrhea. The toxins and the diseases that ETEC causes are not related to E. coli O157:H7
leading cause of travelers’ diarrhea
Norovirus
Norovirus infection can cause the sudden onset of severe vomiting and diarrhea. The virus is highly contagious and commonly spread through food or water that is contaminated during preparation or through contaminated surfaces. You can also be infected through close contact with an infected person.
Norovirus infection occurs most frequently in closed and crowded environments such as hospitals, nursing homes, child care centers, schools and cruise ships
EHEC
Enterohemorrhagic Escherichia coli (EHEC) serotype O157:H7
EHEC is a strain of E. coli that produces a toxin called Shiga toxin.
The toxin causes damage to the lining of the intestinal wall
EHEC was found as the cause of bloody diarrhea that developed after eating undercooked or raw hamburger meat contaminated with the bacteria.
E. coli O157:H7 was first isolated from hamburger and cattle are considered to be the primary reservoir for EHEC O157:H7. Tissue tropism of EHEC at the rectal-anal junction and its stable colonization at this anatomical location ensures its persistence and shedding in feces
Shigella spp.
Shigella is a non-spore forming, non-motile, rod-shaped Gram-negative bacterium which aids in the facilitation of intracellular pathogens. It is able to survive the proteases and acids of the intestinal tract, which allows the bacteria to infect in very small amounts.
As few as 10 cells have been reported to cause infection. Shigellosis primarily affects humans.
Fecal-oral transmission is the main route of Shigella infection. Other modes of transmission include ingestion of contaminated food or water, contact with infected objects, or sexual contact. Outbreaks of Shigella infection are common in places with poor sanitation standards.
5 healthy college roommates develop a rapid (less than 8 hrs) onset of abdominal pain, cramping, fever, to 38.5 C(101.3) vomiting and coupious nonbloody diarrhea while capming. They immediatley return for hydration and diagnosis. A stool culture grows Salmonella enteritidis. all of the statements regarding their clinical syndrome are true except?
a. antibiotic therapy is not indicated
b. bacteremia occurs in fewer that 10% cases
c. the most likely source was undercooked eggs
d. there is no vaccine available for this illness
e. They have enteric (typhoid) fever
e. They have enteric (typhoid) fever
A 33-year-old man sustained compound fractures of his right tibia and fibula during a car accident. Within hours, surgical debridement of the wound and a leg immobilization was completed. The patient improved until four days following the surgery, at which time he became febrile (38°C), tachycardic (120bprn) and complained that his leg was painful. After opening the cast, the lower leg was noted to be swollen, reddish-purple, and exuding a foul- smelling exudate. Crepitations were palpable over the entire gastrocnemius. A Gram-stain of the exudate revealed both Gram-negative and Gram-positive rods. What is the function of the toxin produced by Gram-positive rod most likely growing in this man’s leg?
Degrades lipids in host cell memebrane
Antitoxin is an important component
in the treatment of?
Food-borne botulism
Production of diphtheria toxin is regulated by a repressor that is usually active, but in certain circumstances (such as in a patient) this repressor becomes inactive.
What is the factor which causes the inhibition of the diphtheria toxin repressor?
C. Iron
Note: A and B bind to glycoprotein receptors on cel membrane
The possession of a capsule is often considered to be an important feature of pathogenic bacteria. Which of the following organisms does not possess a capsule?
D. Corynebacterium Diphtheria
Tracheal cytotoxin, involved in the pathogenesis of whooping cough by Bordetella pertussis, is released from the bacterial cell via which mechanism?
Cell wall degrading enzyme
Scarlet fever (scarietna) is known to be caused by bacterial production of which toxin?
Erythrogenic toxin
In May 2011, an outbreak of foodborne illness, presenting with bloody diarrhea and complicated in many cases by hemolytic uremic syndrome, was seen in Germany. In thousands of patients, the causative agent was identified as a lactose-fermenting, Gram- negative, oxidase-negative rod of the novel 0104:H4 serotype. Interestingly, while the pathogen causes a disease similar to that caused by the 0157:H7 strain, it does not have the attaching/effacing genes found in this latter organism. What virulence factor is most likely responsible for the similarities in clinical presentation between the new strain and the 0157:H7 strain?
Shiga toxin
The capsule surrounding Streptococcus pneumoniae makes bacteria pathogenic by what mechanism?
It inhibits phagocytoss by preventing activation of complement and preventing binding of C3b to bacteria
An 18-year-old college student presents with fever, headaches, photophobia, nuchal rigidity, and petechiae. Gram-staining of both blood cultures and cerebrospinal fluid reveals red pairs of kidney bean-shaped bacterial cells. One of the ways this organism is able to survive in the bloodstream is by evading phagocytosis. What is the general structure of the virulence factor most responsible for this ability?
Surface-anchored polysaccharide
all of the following are examples of superficial mycoses except?
a. Tinea versicolor
b. tinea nigra
c. black piedra
d. tinea pedis
e. white piedra
tinea pedis = cutaneous
A 6-week-old infant is brought to the emergency room with a 10-day history of coughing and choking spells. The white blood cell count is elevated with 80% lymphocytes. The child is gasping for breath, experiencing paroxysms of coughing, and vomits twice in the examination room. Encapsulated, gram-negative rods grow out on Bordet-Gengou media. Which of the following microorganisms is the likely cause of these symptoms?
Bordetella Pertussis
