Describe the diseases caused by each and the species included in each:

Describe the diseases caused by each and the species included in each:Answer: Nontyphoidal: Salmonella enteritidis and Salmonella choleraesuis cause...

Salmonella species are divided into typhoidal or nontyphoidal types?

Salmonella species are divided into typhoidal or nontyphoidal types?Answer: Typhoidal: Salmonella typhi and Salmonella paratyphi cause typhoid f...

What is the treatment of Shigella and what medications should be avoided?

What is the treatment of Shigella and what medications should be avoided?Answer: Treatment includes fluid/electrolyte replacement and antibiotics...

What populations are most often affected by Shigella?

What populations are most often affected by Shigella?Answer: Nursing home residents and very young children (ages 2-4 years), especially those in...

How is Shigella transmitted?

How is Shigella transmitted?Answer: Four Fs: fingers, food, flies, fe...

What symptoms are often seen with shigellosis?

What symptoms are often seen with shigellosis?Answer: Dysentery, bloody diarrhea, fever, and lower abdominal cra...

Why is Shigella nonmotile?

Why is Shigella nonmotile?Answer: It lacks the H antigen that codes for motili...

Why does Shigella only cause superficial ulcers and not invade blood vessels?

Why does Shigella only cause superficial ulcers and not invade blood vessels?Answer: Once Shigella enters M cells in the intestine, it uses actin...

What are the reservoirs for Shigella?

What are the reservoirs for Shigella?Answer: Only humans, there are no animal carri...

What are the mechanisms of the two subunits of Shiga toxin?

What are the mechanisms of the two subunits of Shiga toxin?Answer: Subunit A: Inhibits 60S ribosome, stopping protein synthesis, killing the intestinal...

What other bacteria besides Shigella contain the Shiga toxin?

What other bacteria besides Shigella contain the Shiga toxin?Answer: The hemorrhagic and invasive strains of E. c...

Which is more virulent, Salmonella or Shigella?

Which is more virulent, Salmonella or Shigella?Answer: Shigella. Less than 10 organisms are required for Shigella to cause infection because it is...

Salmonella and Shigella are the two important gram-negative bacteria that do not ferment lactose and cause enterocolitis. How are they differentiated?

Salmonella and Shigella are the two important gram-negative bacteria that do not ferment lactose and cause enterocolitis. How are they differentiated?Answer: Salmonella...

Escherichia coli is the most common cause of UTIs, what is the key virulence factor?

Escherichia coli is the most common cause of UTIs, what is the key virulence factor?Answer: P-pili that mediate adhesion to urinary epithel...

Who does EPEC commonly affect?

Who does EPEC commonly affect?Answer: Children, associated with nursery breako...

EPEC adheres to but does not invade intestinal cells and results in flattening of the intestinal villi. What is the consequence of this and how does it present?

EPEC adheres to but does not invade intestinal cells and results in flattening of the intestinal villi. What is the consequence of this and how does it...

How do patients with EIEC present?

How do patients with EIEC present?Answer: Fever and bloody diarrhea with inflammatory white blood cells (compare to EH...

How do these plasmid-encoded proteins act?

How do these plasmid-encoded proteins act?Answer: These plasmid-encoded proteins allow for adherence and direct invasion of epithelial cells in the...

The main virulence factors of EIEC are encoded by a plasmid shared by what other diarrhea causing bacteria?

The main virulence factors of EIEC are encoded by a plasmid shared by what other diarrhea causing bacteria?Answer: Shige...

How is EHEC treated?

How is EHEC treated?Answer: Fluids and supportive therapy. Antibiotics are not useful and may predispose to H...

How are patients typically exposed to EHEC O157:H7?

How are patients typically exposed to EHEC O157:H7?Answer: Undercooked hamburger meat and direct contact with animals (child presents following a...

What is the mechanism that causes hemolytic uremic syndrome (HUS)? What are the features of HUS?

What is the mechanism that causes hemolytic uremic syndrome (HUS)? What are the features of HUS?Answer: HUS occurs when Shiga-like toxin (verocytotoxin)...

How do patients with EHEC present?

How do patients with EHEC present?Answer: Afebrile and bloody diarrhea without inflammatory white blood cells. EHEC strain O157:H7 is associated...

What toxin mediates EHEC diarrhea? What is the mechanism of action?

What toxin mediates EHEC diarrhea? What is the mechanism of action?Answer: Shiga-like toxin (verocytotoxin) inhibits 28S component of the 60S ribosome...

Which other bacterial toxin is similar to LT toxin?

Which other bacterial toxin is similar to LT toxin?Answer: Cholera to...

What is the mechanism of action for ST?

What is the mechanism of action for ST?Answer: Constitutively activates guanylate cyclase leading to increased cyclic guanosine monophosphate (cGMP)...

What is the mechanism of heat LT?

What is the mechanism of heat LT?Answer: Constitutively activates Gs via adenosine diphosphate (ADP) ribosylation leading to constant activation...

What two toxins does ETEC traveler's diarrhea produce?

What two toxins does ETEC traveler's diarrhea produce?1. Heat-labile toxin (LT)2. Heat-stable toxin (...

What are five strains of virulent enteric E. coli?

What are five strains of virulent enteric E. coli?1. Enterotoxigenic E. coli (ETEC)2. Enterohemorrhagic E. coli (EHEC)3. Enteroinvasive E. coli (EIEC)4....

Why would E. coli with the K1 antigen be troubling to physicians?

Why would E. coli with the K1 antigen be troubling to physicians?Answer: K1 strains cause neonatal meningitis, bacteremia, and urinary tract inf...

What does the lack of H antigen signify?

What does the lack of H antigen signify?Answer: H antigen is part of the flagellae. Strains without it lack flagellae and are nonmoti...

What larger structure is the O antigen a part of?

What larger structure is the O antigen a part of?Answer: O antigen is part of lipopolysaccharide (LPS) (endotoxi...

Escherichia coli is classically associated with what three antigens? Which two are commonly used for serology?

Escherichia coli is classically associated with what three antigens? Which two are commonly used for serology?1. O antigen (somatic antigen)2. K antigen...

How is an E. coli infection diagnosed?

How is an E. coli infection diagnosed?Answer: Laboratory culture. Escherichia coli is gram negative, oxidase negative, lactose fermenting, and β-hemolytic...

Where does E. coli normally colonize and how is it transmitted?

Where does E. coli normally colonize and how is it transmitted?Answer: Escherichia coli is considered normal flora of the colon that is transmitted...

Name the common diseases caused by Escherichia coli:

Name the common diseases caused by Escherichia coli:Escherichia coli can cause diarrhea (bloody and nonbloody), urinary tract infections (UTIs) (most...

An 18-year-old woman presents with a sore throat. She is sexually active with a new boyfriend who was recently treated for an unknown sexually transmitted disease (STD). What is the most likely diagnosis? How do you diagnose this?

An 18-year-old woman presents with a sore throat. She is sexually active with a new boyfriend who was recently treated for an unknown sexually transmitted...

A 19-year-old college student presents to the ER with headache, malaise, and fever (102°F). On examination, there is nuchal rigidity and on the lower extremities there are petechiae and purpura. What is the most likely diagnosis?

A 19-year-old college student presents to the ER with headache, malaise, and fever (102°F). On examination, there is nuchal rigidity and on the lower...

A 23-year-old college student presents to his school's student health office complaining of painful urination and purulent urethral discharge for the last 3 days. Analysis of the discharge reveals gram-negative diplococci. What is the offending pathogen and what is the treatment of choice?

A 23-year-old college student presents to his school's student health office complaining of painful urination and purulent urethral discharge for the...

What is the treatment of N. meningitidis infection?

What is the treatment of N. meningitidis infection?Answer: Penicillin G (it does not eradicate N. meningitidis from the nasopharynx) or a cephalosporin...

How are N. meningitidis infections prevented?

How are N. meningitidis infections prevented?Answer: Purified polysaccharide vaccine for groups A, C, Y, and W135. A conjugate vaccine for those...

How is N. meningitidis spread to close contacts? How can N. meningitidis infection be prevented in close contacts?

How is N. meningitidis spread to close contacts? How can N. meningitidis infection be prevented in close contacts?Answer: Spread via asymptomatic...

What is Waterhouse-Friderichsen syndrome and what are its most common manifestations?

What is Waterhouse-Friderichsen syndrome and what are its most common manifestations?Answer: Fulminant meningococcemia leading to septic shock and...

What are typical lumbar puncture findings in bacterial meningitis?

What are typical lumbar puncture findings in bacterial meningitis?Answer: Increased intracranial pressure, turbid cerebrospinal fluid (CSF) with...

What are the key signs of meningitis associated with N. meningitidis infection?

What are the key signs of meningitis associated with N. meningitidis infection?Answer: Fever, nuchal rigidity, vomiting, lethargy, altered mental...

What virulence factor causes the petechiae seen in meningococcal infections?

What virulence factor causes the petechiae seen in meningococcal infections?Answer: Endotoxin-mediated blood vessel destruction leading to blood...

What are the key clinical aspects of a patient who leads to a diagnosis of meningococcemia?

What are the key clinical aspects of a patient who leads to a diagnosis of meningococcemia?Answer: Prodrome of fever, headache, nausea followed by...

What type of immunodeficiency has the greatest risk of N. meningitidis bacteremia?

What type of immunodeficiency has the greatest risk of N. meningitidis bacteremia?Answer: Persons deficient in terminal complement components C6...

What are the two highest risk groups for N. meningitidis infection?

What are the two highest risk groups for N. meningitidis infection?1. Infants 6 months to 2 years (<6 months protected by maternal antibodies)2. Young...

Name one mechanism that allows N. meningitidis to escape host defenses.

Name one mechanism that allows N. meningitidis to escape host defenses.Answer: Antiphagocytic polysaccharide caps...

How does N. meningitidis spread?

How does N. meningitidis spread?Answer: Spread via respiratory secreti...

Name the most important clinical diseases caused by N. meningitidis:

Name the most important clinical diseases caused by N. meningitidis:Answer: Meningitis, meningococcemia (fulminant form: Waterhouse-Friderichsen...

Which part of N. gonorrhoeae undergoes antigenic variation making it difficult to completely eradicate or develop a vaccine?

Which part of N. gonorrhoeae undergoes antigenic variation making it difficult to completely eradicate or develop a vaccine?Answer: Pili, outer membrane...

What other bacterial coinfection must be considered in treating N. gonorrhoeae infections?

What other bacterial coinfection must be considered in treating N. gonorrhoeae infections?Answer: Chlamydial infection is a common coinfection with...

How is N. gonorrhoeae treated?

How is N. gonorrhoeae treated?Answer: Ceftriaxone or a fluoroquinolone. Prophylaxis for neonatal conjunctivitis with silver nitrate or erythromycin...

Describe the key symptoms of both forms of disseminated gonococcal infection.

Describe the key symptoms of both forms of disseminated gonococcal infection.1. Fever, petechial lesions, and arthralgias with erythematous macules over...

What complication of pelvic inflammatory disease often caused by N. gonorrhoeae involves perihepatitis?

What complication of pelvic inflammatory disease often caused by N. gonorrhoeae involves perihepatitis?Answer: Fitz-Hugh and Curtis syndrome. Patients...

What are the major long-term complications of N. gonorrhoeae- induced pelvic inflammatory disease?

What are the major long-term complications of N. gonorrhoeae- induced pelvic inflammatory disease?Answer: Sterility, ectopic pregnancy, abscess,...

What are the most common complications in men of gonococcal urethritis?

What are the most common complications in men of gonococcal urethritis?Answer: Epididymitis, prostatitis, urethral strictu...

Identification of gram-negative diplococci in urethral discharge within which cell type is sufficient for the diagnosis of gonorrhea in men?

Identification of gram-negative diplococci in urethral discharge within which cell type is sufficient for the diagnosis of gonorrhea in men?Answer:&n...

Is vaginal and penile discharge caused by N. gonorrhoeae usually purulent or clear and why?

Is vaginal and penile discharge caused by N. gonorrhoeae usually purulent or clear and why?Answer: Purulent due to a neutrophilic exud...

Name a mechanism by which N. gonorrhoeae evades host defenses:

Name a mechanism by which N. gonorrhoeae evades host defenses:Answer: Antigenic and phase variation of its surface proteins (pi...

Which growth media is used for the isolation and identification of N. gonorrhoeae?

Which growth media is used for the isolation and identification of N. gonorrhoeae?Answer: Thayer-Martin vancomycin, colistin, and nystatin (VCN)...

Name the most common pathologic manifestations of infection by N. gonorrhoeae:

Name the most common pathologic manifestations of infection by N. gonorrhoeae:Answer: Purulent urethritis, cervicitis, epididymitis, pelvic inflammatory...

What enzyme common to both N. gonorrhoeae and N. meningitidis allows them to colonize mucosal surfaces?

What enzyme common to both N. gonorrhoeae and N. meningitidis allows them to colonize mucosal surfaces?Answer: IgA prote...

Describe the sugar fermentation patterns of N. gonorrhoeae and N. meningitidis:

Describe the sugar fermentation patterns of N. gonorrhoeae and N. meningitidis:Answer: N. gonorrhoeae ferments only glucose whereas N. meningitidis...

What is the characteristic appearance of both Neisseria gonorrhoeae and Neisseria meningitidis under the microscope?

What is the characteristic appearance of both Neisseria gonorrhoeae and Neisseria meningitidis under the microscope?Answer: Gram-negative kidney-shaped...

A 55-year-old drum maker presents with nonspecific respiratory symptoms, low-grade fever, and substernal discomfort. Chest x-ray reviews a widening mediastinum. What is the likely diagnosis?

A 55-year-old drum maker presents with nonspecific respiratory symptoms, low-grade fever, and substernal discomfort. Chest x-ray reviews a widening mediastinum....

A young girl presents with fever, sore throat, and regurgitating fluids through her nose. Physical examination reveals cervical lymphadenopathy and a thick, gray, adherent pseudomembrane over the tonsils and throat, and paralysis of the soft palate. What is the likely diagnosis and causative organism?

A young girl presents with fever, sore throat, and regurgitating fluids through her nose. Physical examination reveals cervical lymphadenopathy and a...

Spores of this bacterium enter the body through a traumatic wound, causing pain, edema, and cellulitis. Degenerative enzymes produce gas in tissues, evident by crepitation. Hemolysis, jaundice, and bloody exudates are common. Mortality rates are high. What is the causative organism and disease?

Spores of this bacterium enter the body through a traumatic wound, causing pain, edema, and cellulitis. Degenerative enzymes produce gas in tissues, evident...

CLINICAL VIGNETTES A 43-year-old man who has been taking amoxicillin for 3 weeks to treat an upper respiratory tract infection suddenly develops low-grade fever and diarrhea. What has he most likely developed, which pathogen is causing his new symptoms, and what is the treatment of choice?

CLINICAL VIGNETTES A 43-year-old man who has been taking amoxicillin for 3 weeks to treat an upper respiratory tract infection suddenly develops low-grade...

How is Listeria treated?

How is Listeria treated?Answer: Ampicillin (with gentamicin for serious cases or trimethoprim-sulfamethoxazole for penicillin-allergic patients)....

How is Listeria transmitted?

How is Listeria transmitted?Answer: Most commonly via unpasteurized dairy, meats, and vegetables. Also transplacental spread during deliv...

What patient populations are typically affected by Listeria monocytogenes? Why?

What patient populations are typically affected by Listeria monocytogenes? Why?Answer: Pregnant women, newborns of infected mothers, elderly, and...

What diseases are caused by Listeria?

What diseases are caused by Listeria?Answer: Meningoencephalitis, sepsis, infections in pregnancy (leading to premature birth or fetal death), and...

What type of motility does Listeria display?

What type of motility does Listeria display?Answer: Tumbling motil...

What is unique about the mechanism in which Listeria infects cells?

What is unique about the mechanism in which Listeria infects cells?Answer: Listeria has the ability to spread from cell to cell without entering...

What is the most prominent virulence factor in Listeria? How does it work?

What is the most prominent virulence factor in Listeria? How does it work?Answer: Listeriolysin O toxin penetrates host cell's phagocytic vacuole...

What is unique about the growth characteristic of Listeria?

What is unique about the growth characteristic of Listeria?Answer: It grows well in cold temperature (4°-10°...

LISTERIA MONOCYTOGENES Describe the morphology and special characteristics of Listeria:

LISTERIA MONOCYTOGENES Describe the morphology and special characteristics of Listeria:Answer: Small gram-positive bacillus, facultative intracellular,...

How is diphtheria treated? Prevented?

How is diphtheria treated? Prevented?Answer: Immediate administration of horse serum antitoxin and antibiotics (penicillin G and erythromycin). Prevented...

How is C. diphtheriae diagnosed?

How is C. diphtheriae diagnosed?Answer: Laboratory diagnosis is based on gram-positive rods with metachromatic (blue and red) granul...

What type of agar is used for culturing C. diphtheriae?

What type of agar is used for culturing C. diphtheriae?Answer: Tinsdale potassium tellurite a...

What are the major complications of diphtheria?

What are the major complications of diphtheria?Answer: Physical airway obstruction, myocarditis, demyelination/paralysis of peripheral nervesMnemonic:Diphtheria...

What is exotoxin's mechanism of action?

What is exotoxin's mechanism of action?Answer: ADP ribosylation of elongation factor-2 (EF-2) which blocks tRNA translocation causing inhibition...

How is C. diphtheriae's exotoxin encoded?

How is C. diphtheriae's exotoxin encoded?Answer: β-Prophage ...

How is C. diphtheriae transmitted?

How is C. diphtheriae transmitted?Answer: Via airborne dropl...

What disease is caused by C. diphtheriae? Name its typical symptoms:

What disease is caused by C. diphtheriae? Name its typical symptoms:Answer: Diphtheria. Lymphadenopathy (bull neck) and pseudomembrane pharyngitis...

CORYNEBACTERIUM DIPHTHERIAE Does Corynebacterium diphtheriae form spores or have a capsule?

CORYNEBACTERIUM DIPHTHERIAE Does Corynebacterium diphtheriae form spores or have a capsule?Answer: No, it is nonspore forming and nonencapsulat...

What is in a diphtheria, tetanus, and pertussis (DTaP) childhood vaccine?

What is in a diphtheria, tetanus, and pertussis (DTaP) childhood vaccine?Answer: Diphtheria toxin, tetanus toxoid, and acellular pertussis anti...

What is the tetanus vaccine made of?

What is the tetanus vaccine made of?Answer: Formalin-inactivated tetanus tox...

How is tetanus treated?

How is tetanus treated?Answer: Antitoxin, antibiotics, sedatives, and muscle relaxants to prevent spasms, and debridement of wo...

What are the symptoms of tetanus? Why?

What are the symptoms of tetanus? Why?Answer: Spastic paralysis due to prolonged muscle contracture results from lack of inhibition (ie, loss of...

CLOSTRIDIUM TETANI How does Clostridium tetani cause tetanus?

CLOSTRIDIUM TETANI How does Clostridium tetani cause tetanus?Clostridium tetani acquired from traumatic wound releases tetanus toxin (exotoxin), which...

How is C. perfringens food poisoning treated?

How is C. perfringens food poisoning treated?Answer: Supportive care treatment because it is a self-limiting dise...

How does C. perfringens food poisoning usually present?

How does C. perfringens food poisoning usually present?Answer: Abdominal cramps, diarrhea, and fever that presents 8 to 18 hours after ingestion...

How is gas gangrene treated?

How is gas gangrene treated?Answer: Surgical debridement of necrotic tissue, antibiotics (penicillin plus clindamycin), and hyperbaric oxygen chamber...

What is the role of α-toxin in myonecrosis?

What is the role of α-toxin in myonecrosis?Answer: α-Toxin lyses red blood cells, endothelial cells, leukocytes, and platelets. This facilitates...

Name two major toxins by C. perfringens:

Name two major toxins by C. perfringens:1.α-Toxin (lecithinase)2. Enterotoxin (heat-labile tox...

CLOSTRIDIUM PERFRINGENS Name the conditions most often associated with Clostridium perfringens:

CLOSTRIDIUM PERFRINGENS Name the conditions most often associated with Clostridium perfringens:Answer: Myonecrosis (gas gangrene), cellulitis, food...