Infectious Disease - Details not in Sketchy Bacteria Flashcards
There are about 15 Staphylococcal species that cause disease in humans. Which are most important to know?
- S. aureus*
- S. epidermidis*
- S. saprophyticus*
Besides cluster pattern on plating, what test can be used to differentiate between Staphylococci and Streptococci?
Catalase test
(Staphylococci are catalase-positive)
What does coagulase do?
What Staphylococcal species produce it?
Cleaves fibrinogen to fibrin;
S. aureus, S. argentus (rare)
How does the exfoliative toxin produced by S. aureus cause scalded skin syndrome?
It targets desmoglein I
(both SSS and the autoimmune disease pemphigus vulgaris target desmosomes)
Rapid-onset food poisoning caused by S. aureus will resolve when what happens?
The enterotoxinsareeliminated from the body
Superantigens cross-links ___ cells indiscriminately (can activate up to ___%!) and leads to massive ________ ________.
Superantigen cross-links T cells indiscriminately (can activate up to 50%) and leads to massive cytokine storms.
Superantigens cross-link what?
TCRs and MHC II
(indiscriminate T cell activation)
True/False.
Only a fraction of S. aureus strains produce enterotoxins or TSSTs or exfoliative toxins.
True.
Why does scalded skin syndrome typically only happen in children?
Less desmoglein I in adults
How do bacteria burrow through tissues?
Lytic enzymes
(e.g. collagenases; hyaluronases; etc.)
What bacterial species have Protein A?
S. aureus only
How does S. aureus adhere to mucosal surfaces?
Fibronectin-binding protein
All S. aureus species produce an ______-toxin that lyse human cells.
All S. aureus species produce an α-toxin that lyse human cells.
Which Staphylococci produce toxins?
S. aureus only
S. saprophyticus is normal flora where?
The perineum;
the female genital tract
S. saprophyticus is the ____ most common cause of UTIs and cystitis in young women (after E. coli).
S. saprophyticus is the 2nd most common cause of UTIs and cystitis in young women (after E. coli).
Why does S. saprophyticus need urease?
To survive in urine
Can S. saprophyticus produce biofilms?
Yes.
Where does our microbiota come from?
Breathing, birth canal, touching, eating
True/False.
Lactobacilli, coliforms, and anaerobes are part of the microbiota.
True.
Lactobacilli, coliforms, and anaerobes are part of the microbiota.
You determine that a gram-positive coccus is catalase-negative. What can you test next to determine narrow down the species?
The hemolysis pattern
Describe the differences between α-, β-, and γ-hemolysis.
α-hemolysis (Hgb oxidized to methemoglobin) (greenish-brownish)
β-hemolysis (the bacteria produces hemolysins) (clear, yellow)
γ-hemolysis (no hemolysis) (whiteish)
Identify which respective square represents each of the following:
β-hemolysis
α-hemolysis
γ-hemolysis
β-hemolysis (the bacteria produces hemolysins) (clear, yellow) – Lower right
α-hemolysis (hemoglobin oxidized to methemoglobin) (greenish-brownish) – Lower left
γ-hemolysis (no hemolysis) (whiteish) – Upper right and left
Name the relevant bacteria species classified as each of the following:
Group A strep.
Group B strep.
Group D strep.
Non-groupable
Viridans
Group A strep. — S. pyogenes
Group B strep. — S. agalactiae
Group D strep. — S. bovis
Non-groupable strep. — S. pneumoniae
Viridans strep. — S. mutans, S. sanguinis
What term describes catarrhal inflammation of the mucous membrane in the nose, caused especially by a cold or by hay fever.
Coryza
The roles of S. pyogenes M protein are to mediate ___________ and ___________. It also has anti-__________ activity and degrades _____.
Where is it found?
The roles of S. pyogenes M protein are to mediate adherence and internalization. It also has anti-phagocytic activity and degrades C3b;
bound to the bacterial cell membrane
Besides degrading C3b, S. pyogenes also secretes a peptidase that degrades what other complement factor?
C5a
S. pyogenes secretes streptolysin ____ and ____.
S. pyogenes secretes streptolysin O and S.
C. Acute rheumatic fever
Some S. pyogenes M proteins are similar in structure to proteins found on _______________.
Some S. pyogenes M proteins are similar in structure to proteins found on cardiomyocytes.
Rheumatic fever is a type ____ hypersensitivity reaction.
Poststreptococcal glomerulonephritis is a type ____ hypersensitivity reaction.
Rheumatic fever is a type II hypersensitivity reaction.
Poststreptococcal glomerulonephritis is a type III hypersensitivity reaction.
Poststreptococcal glomerulonephritis typically occurs ~___ _______ after original strep. infection.
Poststreptococcal glomerulonephritis typically occurs ~2 weeks after original strep. infection.
Scarlet fever typically follows streptococcal ___________ and is mediated by ___________ toxin that is activated by lysogenic conversion via a bacteriophage.
Scarlet fever typically follows streptococcal pharyngitis and is mediated by erythrogenic toxin that is activated by lysogenic conversion via a bacteriophage.
Scarlet fever typically follows streptococcal pharyngitis and is mediated by erythrogenic toxin that is activated by __________ conversion via a __________.
Scarlet fever typically follows streptococcal pharyngitis and is mediated by erythrogenic toxin that is activated by lysogenic conversion via a bacteriophage.
The human body does not typically mount immune responses against the S. agalactiae capsule because they are composed of _____ _____ (which is not immunogenic as it is naturally occurring in the body).
The human body does not typically mount immune responses against the S. agalactiae capsule because they are composed of sialic acid (which is not immunogenic as it is naturally occurring in the body).
S. agalactiae can be either β-hemolytic or ___-hemolytic (but is usually β-hemolytic).
S. agalactiae can be either β-hemolytic or γ-hemolytic (but is usually β-hemolytic).
S. pneumoniae utilizes ____________. It is a pore-forming toxin that lyses ________ and ________ and also activates complement. It is not secreted; it is only released upon auto-lysis.
S. pneumoniae utilizes pneumolysin. It is a pore-forming toxin that lyses RBCs and platelets and also activates complement. It is not secreted; it is only released upon auto-lysis.
S. pneumoniae utilizes ___________. It is a pore-forming toxin that lyses RBCs and platelets and also activates complement. It is not _________; it is only released upon _____-_____.
S. pneumoniae utilizes pneumolysin. It is a pore-forming toxin that lyses RBCs and platelets and also activates complement. It is not secreted; it is only released upon auto-lysis.
The most important virulence factors for S. pneumoniae infection are their polysaccharide _________ (which are immunogenic and anti-phagocytic).
The most important virulence factors for S. pneumoniae infection are their polysaccharide capsules (which are immunogenic and anti-phagocytic).
True/False.
Alcohol use disorder increases the risk of S. pneumoniae infection.
True.
S. pneumoniae can be identified by the __________ reaction (methylene blue indicates presence of a __________).
S. pneumoniae can be identified by the Quelling reaction (methylene blue indicates presence of a capsule).
How does S. pneumoniae inhibit C3b activity?
The capsule binds Factor H
____________ bacteria have extra protection against immune/leukocyte responses and are much more likely to have the time to cross the blood-brain barrier and cause meningitis.
Encapsulated bacteria have extra protection against immune/leukocyte responses and are much more likely to have the time to cross the blood-brain barrier and cause meningitis.
What makes the capsule around B. anthracis unique?
It is a polypeptide
(D-glutamate)
What is an eschar?
A cutaneous lesion with central necrosis
What are the three general types of infection caused by B. anthracis?
Cutaneous, pulmonary, GI
How B. anthracis colonies appear when plated?
γ-hemolytic;
sticky, ‘medusa head’ forms on agar
What does it mean if an organism is saprophytic?
It grows out of decaying organic matter
What does it mean if an organism is fastidious?
It only grows when very specific nutrients are included in its medium
Identify which of the following are catalase-positive:
- Staphylococci*
- Streptococci*
- Enterococci*
- Bacilli*
- Cornyebacteria*
Staphylococci
Bacilli
Describe the difference in ingestion of B. cereus toxins or spores.
Ingestion of toxin-containing foods: heat-______ enterotoxin (cereulide) –> rapid-onset ______ (<6 hours).
Ingestion of spores (activation in gut): heat-_____ enterotoxin –> slow-onset ______ (>6 hours).
Ingestion of toxin-containing foods: heat-stable enterotoxin (cereulide) –> rapid-onset emesis (<6 hours).
Ingestion of spores (activation in gut): heat-labile enterotoxin –> slow-onset watery diarrhea (>6 hours).
- Bacilli* are _______ ___robes.
- Clostridia* are _______ ___robes.
- Bacilli* are obligate aerobes.
- Clostridia* are obligate** **anaerobes.
Name the following toxins of C. perfringens:
___-toxin – pore-forming toxin
___-toxin (aka lecithinase or phospholipase)
σ-toxin – pore-forming toxin
α-toxin (aka lecithinase or phospholipase)
What bacteria results in this hemolysis pattern?
Which toxin causes the interior and which toxin causes the exterior?
C. perfringens;
Interior: σ-toxin
Exterior: α-toxin
Describe the C. perfringens hemolysis pattern.
Double zone of hemolysis
What test can be used to identify C. perfringens due to its phospholipase activity?
What toxin is it showing?
The Nagler reaction;
α-toxin
Why is hyperbaric O2 useful in treating cases of C. perfringens infection?
It is an obligate anaerobe
Which Gram-positive bacteria are a small part of the normal gut flora?
C. difficile
What are four gram-positive rods that are NOT spore-forming?
- C. diphtheriae*, L. monocytogenes;
- A. israelii*; N. asteroides
Why is C. tetani infection more likely in geriatric patients?
Waxing immunity to toxin
(toxoid vaccine wears off)
What is the usual cause of death in patients with untreated C. tetani infection?
Suffocation
(respiratory muscles continually tensed/exhausted)
Identify which of the following are part of the normal body flora:
Salmonella enteridis
E. coli
Shigella dysenteriae
Yersinia pestis
P. mirabilis
K. pneumoniae
E. coli
P. mirabilis
K. pneumoniae
True/False.
All Enterobacteriaceae are bile-sensitive and oxidase-positive.
False.
All Enterobacteriaceae are bile-resistant and oxidase-negative.
Identify which of the following are part of the Enterobacteriaceae class:
- H. pylori*
- C. diphtheriae*
- E. coli*
- Y. pestis*
- S. dysenteriae*
- P. aeruginosa*
- C. jejuni*
- V. cholerae*
- S. typhi*
E. coli
S. tyhpi
Y. pestis
What are two key factors that help differentiate Enterobacteriaceae from one another?
Motility;
H2S production
_________ ________ agar is used to select for Gram-negative H2S-producing organisms.
This is especially important in differentiating Salmonella and Shigella.
Hektoen enteric agar is used to select for Gram-negative H2S-producing organisms.
This is especially important in differentiating Salmonella and Shigella.
Hektoen enteric agar is used to select for Gram-negative H2S-producing organisms.
This is especially important in differentiating _________ and _________.
Hektoen enteric agar is used to select for Gram-negative H2S-producing organisms.
This is especially important in differentiating Salmonella and Shigella.
On Hektoen enteric agar, Salmonella produces _______ colonies and Shigella produces _______ colonies.
On Hektoen enteric agar, Salmonella produces black colonies and Shigella produces green colonies.
On Hektoen enteric agar, __________ produces black colonies and __________ produces green colonies.
On Hektoen enteric agar, Salmonella produces black colonies and Shigella produces green colonies.
Identify which of the following can ferment lactose:
E. coli
Enterobacter spp.
Salmonella spp.
P. mirabilis
E. coli
Enterobacter spp.
What is indicated by the ‘O’ and ‘H’ in O157:H7 E. coli?
Types of O antigen and H antigen
True/False.
All Enterobacteriaceae have endotoxins and produce exotoxins.
True.
Most E. coli is flushed from the bladder/urethra via normal voiding because there are no type ___ pili receptors in the bladder.
E. coli can stick in the bladder if they have the __-pili as well as type 1 pili.
Most E. coli is flushed from the bladder/urethra via normal voiding because there are no type 1 pili receptors in the bladder.
E. coli can stick in the bladder if they have the P-pili as well as type 1 pili.
Citrobacter are lactose-fermenting bacteria similar to __________ that are biochemically and serologically similar to __________.
Citrobacter are lactose-fermenting bacteria similar to Enterobacter that are biochemically and serologically similar to Salmonella.
- Shigella* ______ (are/are not) H2S-producing.
- Shigella* ______ (are/are not) motile.
- Shigella* are not H2S-producing (green colonies on Hektoen enteric agar).
- Shigella* are not motile.
Name a few species of Shigella spp.
Which one produces Shiga toxin and the most severe disease?
S. dysenteriae,
- S. sonnei*,
- S. flexneri*,
- S. boydii*
- Salmonella* ______ (are/are not) H2S-producing.
- Salmonella* ______ (are/are not) motile.
- Salmonella* are H2S-producing (black colonies on Hektoen enteric agar).
- Salmonella* are motile.
_________ (Shigella/Salmonella) are H2S-producing (black colonies on Hektoen enteric agar).
_________ (Shigella/Salmonella) are not motile.
Salmonella are H2S-producing (black colonies on Hektoen enteric agar).
Shigella are not motile.
Describe the difference between how enteropathogenic, enterotoxigenic, and enterohemorrhagic E. coli interact with human enterocytes.
Describe the difference between how enteroaggregative, enteroinvasive, and uropathogenic E. coli interact with human enterocytes.
Describe the different types of E. coli as shown in the attached image.
B. P. mirabilis
(Note: urease-producing; lactose-negative; swarming motility in right image)
Name a few Gram-negative, oxidase-positive, motile rods.
- Campylobacter jejuni.*,
- Pseudomonas aeruginosa*,
- Helicobacter* pylori,
- Vibrio cholerae*
Which of the following are oxidase-positive?
Campylobacter jejuni
Pseudomonas aeruginosa
Helicobacter pylori
Vibrio cholerae
Campylobacter jejuni
Pseudomonas aeruginosa
Helicobacter pylori
Vibrio cholerae
Which of the following are motile?
Campylobacter jejuni
Pseudomonas aeruginosa
Helicobacter pylori
Vibrio cholerae
Campylobacter jejuni
Pseudomonas aeruginosa
Helicobacter pylori
Vibrio cholerae
D. Pseudomonas aeruginosa
True/False.
Pseudomonas aeruginosa is rare but can be found sometimes in water.
False.
Pseudomonas aeruginosa is ubiquitous and is often found in soil, vegetation, water, moist reservoirs, etc.
How are Pseudomonas aeruginosa flagella oriented?
Polar flagella
Pseudomonas aeruginosa produces a blue-green pigmentation (via pyocyanin and pyoveridin) that can be seen on _______ and in _______.
Pseudomonas aeruginosa produces a blue-green pigmentation (via pyocyanin and pyoveridin) that can be seen on agar and in wounds.
How common is Pseudomonas aeruginosa in hospital settings?
Pseudomonas aeruginosa are able to adhere well to mucosal surfaces via _______ and _______.
Pseudomonas aeruginosa are able to adhere well to mucosal surfaces via pili and biofilms.
With what form of hemolysis does Pseudomonas aeruginosa present on agar?
β-hemolysis
Burkholderia cepacia are 17 different species that cause ___________, ___________, and ___________ infections.
These infections are more common in CF, immunocompromised, chronic granulomatous disease patients, and neonates.
Burkholderia cepacia are 17 different species that cause septicemia, respiratory, and urinary tract infections.
These infections are more common in CF patients, immunocompromised, chronic granulomatous disease patients, and neonates.
Burkholderia cepacia are 17 different species that cause septicemia, respiratory, and urinary tract infections.
These infections are more common in _______ patients, _________ patients, __________________ patients, and _________.
Burkholderia cepacia are 17 different species that cause septicemia, respiratory, and urinary tract infections.
These infections are more common in CF patients, immunocompromised patients, chronic granulomatous disease patients, and neonates.
____________ ___________ are 17 different species that cause septicemia, respiratory, and urinary tract infections.
These infections are more common in CF patients, immunocompromised patients, chronic granulomatous disease patients, and neonates.
Burkholderia cepacia are 17 different species that cause septicemia, respiratory, and urinary tract infections.
These infections are more common in CF patients, immunocompromised patients, chronic granulomatous disease patients, and neonates.
V. cholerae is a _____-volume, watery diarrhea.
The rice water stools are caused by little pieces of _______ in stool.
V. cholerae is a high-volume, watery diarrhea. (Fluid lost is often measured in liters.)
The rice water stools are caused by little pieces of biofilm in stool.
V. cholerae is halophilic. What does this mean?
What is the typical cause of death in patients with cholera?
How is cholera treated?
V. cholerae is salt-requiring;
dehydration;
ORS
C. Vibrio vulnificus
(flesh-eating bacteria associated with salt water with very rapid progression)
- Campylobacter
Name a disease that can cause flesh-eating infection that is often associated with exposure to salt water and seafood (with very rapid progression to death).
Vibrio vulnificus
Name a species of the Vibrio family that causes a food-borne gastroenteritis with a 2% mortality rate (or wound infection with a 25% mortality rate). There are ~45,000 U.S. cases per year.
Name a species of the Vibrio family with a 50% mortality rate (100% if antibiotics are not started within 72 hours of illness onset) that is associated with contact with salt water. There are ~100 U.S. cases per year.
- Vibrio parahaemolyticus*
- Vibrio vulnificus*
Describe the infections, incidence rates, and mortality rates for the following bacteria.
- Vibrio parahaemolyticus*
- Vibrio vulnificus*
A food-borne gastroenteritis (86% of cases) with a 2% mortality rate (or wound infection with a 25% mortality rate).
There are ~45,000 U.S. cases per year.
A 50% mortality rate (100% if antibiotics are not started within 72 hours of illness onset) that is associated with contact with salt water.
There are ~100 U.S. cases per year.
Vibrio vulnificus is especially likely to cause septicemia in patients with underlying medical conditions, especially ________ disease.
Vibrio vulnificus is especially likely to cause septicemia in patients with underlying medical conditions, especially liver disease.
Name three members of the Vibrio family.
Vibrio cholerae (causes cholera)
Vibrio parahaemolyticus (fairly common cause of vibriosis)
Vibrio vulnificus (deadly cause of vibriosis)
Campylobacter jejuni is a fastidious organism that requires very selective media and growth conditions. It has to be incubated at ___ C, under micro_________ conditions.
Campylobacter jejuni is a fastidious organism that requires very selective media and growth conditions. It has to be incubated at 42°C, under microaerophilic conditions.
It is significant that Campylobacter jejuni must be cultured at 42°C as that is the natural temperature of ________, a commonly colonized carrier of C. jejuni.
It is significant that Campylobacter jejuni must be cultured at 42°C as that is the natural temperature of birds, a commonly colonized carrier of C. jejuni.
Campylobacter jejuni are very, very ________ in gut epithelia, thus explaining why infection often causes bloody diarrhea.
Campylobacter jejuni are very, very invasive in gut epithelia, thus explaining why infection often causes bloody diarrhea.
How long does infection with Campylobacter jejuni typically last without treatment?
And with treatment?
1 - 3 weeks;
<3 days
What does the CDC estimate is the most common cause of bacterial diarrhea in the U.S.?
C. jejuni
___ / 1000 cases of C. jejuni result in Guillan-Barre syndrome, usually ocurring ~___ weeks after infection.
1 / 1000 cases of C. jejuni result in Guillan-Barre syndrome, usually ocurring ~2 weeks after infection.
~___% of the world is colonized by H. pylori (~___% are asymptomatic).
~50% of the world is colonized by H. pylori (~90% are asymptomatic).
An individual presenting with duodenal ulcers is asked to drink a solution containing radiolabeled urea. If the individual has an overgrowth of H. pylori, what do you expect to occur?
Exhaled radiolabeled CO2
What is the general source of most Pseudomonas infections?
What is the general source of most Campylobacter infections?
What is the general source of most Helicobacter infections?
What is the general source of most Vibrio infections?
Ubiquitous in moist reservoirs;
contaminated poultry (or other animals);
fecal-oral;
contaminated water, shellfish
N. meningitidis
The petechiae seen in N. meningitidis are caused by membrane shedding of _______.
N. meningitidis _______ (are/are not) motile.
What does N. meningitidis use to sequester iron?
The petechiae seen in N. meningitidis are caused by membrane shedding of Lipid A.
N. meningitidis are not motile.
What does N. meningitidis use to sequester iron? Siderophores
N. gonorrheae ______ (are/are not) motile.
N. gonorrheae are not motile.
True/False.
Lipopolysaccharide (LPS) is a major virulence factor for both N. meningitidis and H. influenzae.
False.
Lipooligosaccharide (LOS) is a major virulence factor for both N. meningitidis and H. influenzae.
In what age range do most meningitis cases caused by N. meningitidis meningitis occur?
Childhood
(also a small bump in cases around age 20)
Why don’t we produce a vaccine against type B N. meningitidis?
Type B capsule has sialic acid
(we don’t want to increase the likelihood of autoimmunity)
B. pertussis
Bortadella pertussis are:
oxidase-__________
______capsulated
very _______ diplococci/coccobacilli
Bortadella pertussis are:
oxidase-positive
encapsulated
very small diplococci/coccobacilli
Why is completely eliminating B. pertussis very possible?
It is a strictly human pathogen
(could be eliminated through vaccinations)
What agar is necessary for B. pertussis to grow?
Bordet-Gengou agar
(agar treated with nicotinamide and charcoal)
L. pneumophila
(high fever + pneumonia + diarrhea + absent organisms)
True/False.
L. pneumophila stains poorly with Gram stain
True.
L. pneumophila are facultatively intracellular within ____________ (normally reside within environmental amoebas).
They are typically found in watery or moist environments due to their ability to form what?
L. pneumophila are facultatively intracellular within macrophages (normally reside within environmental amoebas).
Biofilms
B. Haemophilus influenzae type B
H. influenzae requires V-factor and X-factor.
What is V-factor?
What is X-factor?
Both of these are found in what agar?
NAD
hematin
chocolate agar
B. (often transmitted by birds — only the turkey farm is useful information here. All the other S/Sy are farily non-specific.)
As C. trachomatis cannot produce muramic acid, it also cannot produce __________, of which muramic acid is a component.
As C. trachomatis cannot produce muramic acid, it also cannot produce peptidoglycan, of which muramic acid is a component.
C. trachomatis is an obligate intracellular energy parasite that has a strong ability to infect cells at the ____________ ________.
C. trachomatis is an obligate intracellular energy parasite that has a strong ability to infect cells at the squamocolumnar junction.
C. trachomatis is cultured in _______ cells with _______ stain used to illustrate the inclusions.
C. trachomatis is cultured in McCoy cells with iodine stain used to illustrate the inclusions.
Why is Listeriosis more common in pregnant women?
Due to decreased cell-mediated immune activity
(because of increased estrogen / progesterone)
Why doesn’t Listeriosis need a capsule to cause meningitis?
It’s an intracellular pathogen
L. monocytogenes are Gram-_________, ______capsulated, facultative intracellular ________ (shape).
L. monocytogenes are Gram-positive, unencapsulated, facultative intracellular coccobacilli.
What membrane-damaging toxin does L. monocytogenes produce?
Listeriolysin O
Name three bacterial families that all form actin rockets for transport.
- Listeria spp.*
- Shigella spp.*
- Rickettsia spp.*
What are the three genuses within the Ricketsiae family?
- Rickettsia*
- Coxiella*
- Ehrlichia*
How are most genuses within the Ricketsiae (Rickettsia, Coxiella, Ehrlichia) family transmitted?
Do the infections arise rapidly or slowly?
Arthropods;
rapidly
Rickettsia ricketsii adhere to and have a predilection for what cell type?
What is the result?
Endothelial cells;
vasculitis
Why might a Rickettsial infection present with negative serological tests and blood cultures?
They are obligate intracellular organisms
- Rickettsia prowazekii* typically causes a centri_____ rash.
- Rickettsia rickettsii* typically causes a centri_____ rash.
- Rickettsia prowazekii* typically causes a centrifugal rash (trunk to extremities).
- Rickettsia rickettsii* typically causes a centripetal rash (extremities to trunk).
Where is Rickettsia rickettsii infection (and RMSF) most common?
- Rickettsia* ____________ can cause Rocky Mountain spotted fever (RMSF).
- Rickettsia* ____________ can cause epidemic typhus.
- Rickettsia* rickettsii can cause Rocky Mountain spotted fever (RMSF).
- Rickettsia* prowazekii can cause epidemic typhus.
The rash associated with epidemic typhus (Rickettsia prowazekii) characteristically avoids what part(s) of the body?
The palms and soles
Brill-Zinsser disease manifests years after infection with what organism?
Rickettsia prowazekii
True/False.
Treatment for RMSF or typhus should be started on clinical suspicion alone (don’t wait for confirmatory labs).
True.
- R. typhi* (the cause of endemic typhus) is transmitted to humans via what arthropod?
- R. prowazekii* (the cause of epidemic typhus) is transmitted to humans via what arthropod?
- R. ricketsii* (the cause of RMSF) is transmitted to humans via what arthropod?
Flea;
louse;
Dermacentor tick
A. Ehrlichiosis
Ehrlichia and anaplasma are both characterized by:
Invasion/destruction of __________ / __________
Being ______-borne
Obligate intracellular organisms
A _________ lifecycle (like Chlamydia and Coxiella)
A similar presentation to _______ but without the rash
Ehrlichia and anaplasma are both characterized by:
Invasion/destruction of monocyes / macrophages
Being tick-borne
Obligate intracellular organisms
A biphasic lifecycle (like Chlamydia and Coxiella)
A similar presentation to RMSF but without the rash
__________ and __________ are both characterized by:
Invasion/destruction of monocyes / macrophages
Being tick-borne
Obligate intracellular organisms
A biphasic lifecycle (like Chlamydia and Coxiella)
A similar presentation to RMSF but without the rash
Ehrlichia and anaplasma are both characterized by:
Invasion/destruction of monocyes / macrophages
Being tick-borne
Obligate intracellular organisms
A biphasic lifecycle (like Chlamydia and Coxiella)
A similar presentation to RMSF but without the rash
Cat scratch fever (B. henselae)
Describe the lifecycle of Bartonella henselae between its arthropod host and infected humans.
All zoonotic infections have vectors except ________.
All zoonotic diseases have vectors except Coxiella.
All zoonotic diseases are obligate intracellular except ___________.
All zoonotic diseases are obligate intracellular except Bartonella.
Actinomyces israelii
What is the likely diagnosis?
Nocardia asteroides
Nocardia asteroids:
Typically causes ________ infection in immunocompromised patients
Acid-fast + produces _________ lung lesions similar to TB
May cause cutaneous lesions follow minor ______
Nocardia asteroids:
Typically causes pulmonary infection in immunocompromised patients
Acid-fast + produces pulmonary lung lesions similar to TB
May cause cutaneous lesions follow minor trauma
Name an abcess-forming filamentous Gram-positive rod besides Nocardia asteroides.
Nocardia brasiliensis
A homeless man presents with bacillary angiomatosis and chronic lymphadenopathy. He reports having felt feverish most of last week. He is hospitalized for other reasons and is noticed over the next two weeks to have a fever that lasts about 5 days at a time before remitting and then relapsing.
What is the likely diagnosis?
Bartonella quintana
(‘trench fever’)
True/False.
Tularemia is a fairly common endemic infection and is most often seen in children playing with rabbits purchased at pet shops.
False.
Tularemia is a fairly rare endemic infection and is most often seen in hunters, gardeners, and veterinarians.
D. Bacteriodes fragilis — gram-negative rod (Normally found in gut; anaerobic but aerotolerant; abcess former)
Bacteriodes are gram-________ rods that are:
normally found in the ____,
___robic but ____tolerant,
_______ formers.
Bacteriodes are gram-negative rods that are:
normally found in the gut,
anaerobic but aerotolerant,
abcess formers.
What is the most commonly isolated gram-negative anaerobic rod in peritoneal infections (e.g. ruptured appendix)?
Bacteroides fragilis
What in this history might steer you towards a diagnosis of Mycoplasma infection?
Dry cough,
no bacteria on Gram stain,
X-ray more severe than presentation,
slow onset,
Summer instead of Winter,
high fever
Mycoplasma lacks a _____ _____ and so is resistant to antibiotics that target _____ _____s.
Mycoplasma lacks a cell wall and so is resistant to antibiotics that target cell walls.
Identify any of the following that Mycoplasma has:
Cell wall
Peptidoglycan
LPS
None of these
Mycoplasma uses a __________ organelle to attach to _____ acid on pulmonary cells. It then burrows where?
Mycoplasma uses a P1 adhesion organelle to attach to sialic acid on pulmonary cells.
The intercellular space (burrowing between cells)
Mycoplasma and Ureaplasma are both types of __________, meaning they are tiny and have no cell wall.
Mycoplasma and Ureaplasma are both types of mollicutes, meaning they are tiny and have no cell wall.
True/False.
Mycoplasma and ureaplasma exhibit both antigenic variation and free radical production.
True.
Mycoplasma typically has a very _____ infectious dose.
Mycoplasma typically has a very low infectious dose.
What is a common cause of community-acquired ARDS?
Mycoplasma
True/False.
The cold agglutinins seen in Mycoplasma are complement-mediated.
False.
The cold agglutinins seen in Mycoplasma are antibody-mediated.
True/False.
Infection with Mycoplasma will typically show up as an IgM response.
True.
Mycoplasma adhere to pulmonary cell sialic acid via __ _______ organelles.
They inhibit the mucociliary escalator via _________.
Mycoplasma adhere to pulmonary cell sialic acid via P1 adhesion organelles.
They inhibit the mucociliary escalator via ciliostasis.
Which strain of Mycoplasma typically causes an atypical bronchopneumonia?
Which strain typically manifests as adult genitourinary infections or neonatal respiratory and genitourinary infections?
Which strain typically manifests as adult genitourinary infections only?
- Mycoplasma pneumoniae* (transmitted via respiratory droplets)
- Mycoplasma hominis* (transmitted via sexual contact)
- Mycoplasma genitalium* (transmitted via sexual contact))
Which strain of Mycoplasma typically manifests as adult genitourinary infections or neonatal respiratory and genitourinary infections?
What other mollicute presents similarly?
- Mycoplasma hominis*;
- ureaplasma urealyticum*
Where did she likely acquire TB?
How did it become reactivated?
AIDS work in South Africa;
the TNF-α inhibitor
Besides tuberculosis infection, what might be some other disorders in your differential?
Sarcoidosis, Nocardia, some fungi, etc.
Cell wall ________ acid – very hydro______ lipid layer — does not let ______ stain through.
Cell wall mycolic acid – very hydrophobic lipid layer — does not let Gram stain through.
Describe the structural differences between Gram-negative, Gram-positive, and acid-fast bactera.
What does it mean that Mycobacteria are acid-fast?
Must use non-Gram-stain pigments which are then washed with acid (acid can’t make it through the lipid layer)
What prevents most antibiotics from entering Mycobacteria?
The thick, hydrophobic mycolic acid layer
What endo- or exotoxins do Mycobacteria have?
None
Mycobacterium tuberculosis requires complex, ____-rich media for growth (e.g. L__________-J______; M_________).
Mycobacterium tuberculosis requires complex, lipid-rich media for growth (e.g. Lowenstein-Jensen; Middlebrook).
How is M. leprae grown in vitro?
It is not
What is indicated by a positive PPD test?
Prior TB infection
Is TB transmitted via aerosols or respiratory droplets?
Aerosols
Cause(s) of PPD false negatives:
Cause(s) of PPD false positives:
Cause(s) of PPD false negatives: immunocompromise or very recent infection (< 3 months)
Cause(s) of PPD false positives: BCG
Latent TB has a ___% general likelihood of lifetime reactivation, but a __% likelihood per year for HIV/AIDS patients.
Latent TB has a 10% general likelihood of lifetime reactivation, but a 10% likelihood per year for HIV/AIDS patients.
Where is multi-drug resistant TB most common?
Mycobacteria virulence factors:
Intracellular growth
Highly antigenic mycolic acid
Prevents formation of _______________ (TB-specific)
Inhibits MHC ____ function
Prevents host ______sis
Mycobacteria virulence factors:
Intracellular growth
Highly antigenic mycolic acid
Prevents formation of phagosomes (TB-specific)
Inhibits MHC II function
Prevents host apoptosis
Mycobacteria virulence factors:
_____cellular growth
Highly _________ic mycolic acid
Prevents formation of phagosomes (___-specific)
Inhibits MHC II function
Prevents host apoptosis
Mycobacteria virulence factors:
Intracellular growth
Highly antigenic mycolic acid
Prevents formation of phagosomes (TB-specific)
Inhibits MHC II function
Prevents host apoptosis
Name a few ‘atypical’ Mycobacteria spp. that cause TB-like disease.
Bold the more common of the three.
M. kanasii
M. avium-intracellulare (MAC) complex
M. scrofulaceum
Name a few ‘atypical’ Mycobacteria spp. that cause soft tissue infections.
- M. marinum*
- M. ulcerans*
- M. fortuitum*
- M. abcessus*
What pre-disposing conditions place individuals at increased risk for infection by M. kanasii and M. avium-intracellulare?
Previous TB;
COPD;
lung malignancy
AIDS
True/False.
Non-TB Mycobacteria are not acid-fast and are transmitted from person-to-person.
False.
Non-TB Mycobacteria are acid-fast and are transmitted environmentally, not from person-to-person.
In what countries is infection with M. leprae more common?
India;
Brazil
Which is more effective at fighting M. leprae, the TH1 or TH2 response?
TH1 response
(TH2 is less effective as the organism is intracellular)
True/False.
A vaccine is being prepared for M. leprae.
True.
Which Mycobacteria spp. is especially associated with AIDS?
M. avium-intracellulare
Which Mycobacteria spp. causes ‘fish-tank granulomas’?
M. marinum
Which Mycobacteria spp. is associated with trauma and surgical wounds?
M. fortuitum
Hansen’s disease
(M. leprae)
Where do M. leprae replicate?
Schwann cells and histiocytes
What infectious agent is known as ‘the great imitator’?
Why?
Treponema pallidum;
multiple presentations over several stages that all appear similar to multiple diseases
Describe the timeline of syphilis.
C. Check for antibodies to cardiolipin antibodies (titers decrease with treatment; although anti-treponemal antibodies will remain)
In infection with T. pallidum, __________ titers decrease with treatment and __________ titers are unchanged by treatment.
In infection with T. pallidum, anti-cardiolipin titers decrease with treatment and anti-treponemal titers are unchanged by treatment.
In infection with T. pallidum, anti-cardiolipin titers __________ with treatment and anti-treponemal titers __________ by treatment.
In infection with T. pallidum, anti-cardiolipin titers decrease with treatment and anti-treponemal titers are unchanged by treatment.
VDRL and RPR both check for ___________ (which is found in all __________ membranes).
VDRL and RPR both check for cardiolipin (which is found in all mitochondrial membranes).
What animals can carry Treponema pallidum?
Humans only
Which stages of syphilis are infectious?
All stages
True/False.
Treponema pallidum expresses LPS as a virulence factor and coats itself in a fibronectin coat to avoid detection by the immune system.
False.
Treponema pallidum does not express LPS as a virulence factor and coats itself in a fibronectin coat to avoid detection by the immune system (a ‘self’ protein).
The _______–__________ reaction is a reaction to endotoxin-like products released by the death of harmful microorganisms within the body during antibiotic treatment.
The Jarisch–Herxheimer reaction is a reaction to endotoxin-like products released by the death of harmful microorganisms within the body during antibiotic treatment.
The Jarisch–Herxheimer reaction is a reaction to endotoxin-like products released by the death of harmful microorganisms within the body during _________ treatment.
The Jarisch–Herxheimer reaction is a reaction to endotoxin-like products released by the death of harmful microorganisms within the body during antibiotic treatment.
Name the following Treponema pallidum spp. (subspecies):
Endemic syphilis (Bejel) — oral papules, gummas (Africa, Asia, Australia)
Yaws — destructive lesions of skin and bone (Africa, Asia, South America)
Pinta — disseminated hypopigmentation –> scarring and disfigurement
- T. pallidum spp. endemicum*
- T. pallidum spp. pertenue*
- T. pallidum spp. carateum*
Name the following Treponema pallidum spp. (subspecies):
T. pallidum spp. endemicum — oral papules, gummas (Africa, Asia, Australia)
T. pallidum spp. pertenue — destructive lesions of skin and bone (Africa, Asia, South America)
T. pallidum spp. carateum — disseminated hypopigmentation –> scarring and disfigurement
Endemic syphilis (Bejel)
Yaws
Pinta
What part of Borrelia burgdorferi is characterized by antigenic variation?
Outer membrane proteins
Borrelia burgdorferi binds factor ___ to degrade ____; it also binds fibronectin. It lacks classic ____.
Borrelia burgdorferi binds factor H to degrade C3b; it also binds fibronectin. It lacks classic LPS.
Ixodes ticks in what stage of the lifecycle causes 90% of cases of Lyme disease?
How many cases occur due to human-to-human transmission?
Nymph Ixodes ticks;
0%
What parts of the U.S. have the highest rates of Lyme disease?
Describe what proportion of Lyme disease cases are characterized by each of the following S/Sy:
Erythema chronicum migrans
Systemic symptoms
Severe fatigue and migratory pain
Nearly all
Some
50%
Describe what proportion of Lyme disease cases are characterized by each of the following S/Sy:
Neurologic presentation
Cardiac dysfunction
Migratory polyarthritis
15%
8%
60%
C. (spirochetes in salivary glands –> must get abdomen and head out together; suffocation is ineffective)
True/False.
The only spirochete that can be visualized via dark-field microscopy is Treponema pallidum.
False.
Is Leptospira interrogans aerobic or anaerobic?
Aerobic
What organism causes louse-borne relapsing fever?
Is it epidemic or endemic?
Borrelia recurrentis (epidemic)
What organism causes tick-borne relapsing fever?
Is it epidemic or endemic?
Borrelia hermsii (endemic)
What organism causes tick-borne relapsing fever?
What organism causes louse-borne relapsing fever?
- Borrelia hermsii*
- Borrelia recurrentis*
Why does relapsing fever occur over and over?
Antigenic variation
Which of the following is characterized by high bacterial levels in the blood? How about thrombocytopenia? Which is fatal?
Lyme disease
Relapsing fever
All relapsing fever
(myocarditis is the most common cause of death)
