What are the 7 most common normal respiratory tract flora? (think: B.S. C.O.A.C.H.!)
Branhamella
Streptococcus mutans
Corynebacteria
Oral streptococci
Anaerobic cocci
Candida albicans
Haemophilus influenzae
Match the following. May repeat more than once.
Invade healthy respiratory tract via:
1. adhesion to mucosal surface
2. interfere with cilia
3. resist alveolar macrophages
4. damage local tissue
A. Influenza virus
B. Mycobacterium tuberculosis
C. S. pyogenes
D. Rhinovirus
E. Corynebacterium diptheria
F. Chlamydia pneumoniae
G. B. pertusis
H. S. pneumoniae
I. Legionella pneumophila
J. Mycoplasma pneumoniae
1. adhesion to mucosal surface - A. Influenza virus, D. Rhinovirus, C. S. pyogenes, H. S. pneumoniae, J. Mycoplasma pneumoniae, F. Chlamydia pneumoniae
2. interfere with cilia - G. B. pertusis, H. S. pneumoniae, J. Mycoplasma pneumoniae
3. resist alveolar macrophages - I. Legionella pneumophila, B. Mycobacterium tuberculosis
4. damage local tissue - H. S. pneumoniae, E. Corynebacterium diptheria
What 3 organisms are the main cause of bacterial oral URIs?
oral anaerobes
A. israelii
V. streptococci
What organism is the main cause of fungal oral URIs?
C. albicans
What 2 organisms are the main cause of bacterial ear and sinus URIs?
S. pneumoniae
H. influenzae
What 3 organisms are the main cause of bacterial pharyngeal URIs?
C. diptheriae
B. pertussis
S. pyogenes
What are some specific laboratory tests to ID C. albicans that causes URIs?
specimen collection
KOH or gram stains: gram+ round yeast cells with hyphae
germ tube formation
What is the mode of transmission for C. albicans that causes URIs?
antimicrobial treatment
compromised patients: AIDS, leukopenia, corticosteroid use
indwelling devices or cancer chemotherapy
diabetes
Clinical ID of an organism that is gram+ lancet-shaped, diplococci, sensitive to Optochin and has a polysaccharide capsule is descriptive of what upper respiratory tract pathogen?
Streptococcus pneumoniae
What is the mode of transmission for S. pneumoniae that causes URIs?
What is the mode of transmission for H. influenzae that causes URIs?
colonization of nasopharynx
causes otitis media and sinusitis, can lead to meningitis
vaccine available
What are some specific laboratory tests to ID S. pyogenes that causes URIs?
throat swab of tonsils or pharynx
culture on BAP > beta-hemolysis
gram+ cocci in chains
Lancefield Ggroup A
Catalase-
Bacitracin sensitive
What is the mode of transmission for C. diptheria that causes URIs?
inhalation of droplets
contact with cutaneous infection or fomites
What are some specific laboratory tests to ID B. pertussis that causes URIs?
deep nasopharyngeal culture, must be done immediately - very slow growth
CAP + antibiotic media
gram- coccobacillus (looks like H. influenzae)
direct fluorescent antibody detection
What is the mode of transmission for B. pertussis that causes URIs?
spread through droplet
only infects human respiratory tract
highly contagious, may cause edema and hemorrhages in brain
A 22-year old male goes to his dentist with complaints of bleeding gums after flossing or brushing. He tells the dentist that he hasn't always had great dental hygiene, but he decided to change his habits after his medical student friend told him that he could develop acute necrotizing ulcerative gingivitis (trench mouth) and/or tooth loss if left untreated. If a biopsy of his gums were taken and examined, what pathogen(s) would you most likely find?
B. oral anaerobes
If you examined a sample of an oral abscess, following a tooth extraction, under a microscope and found PMNs, lymphocytes, and predominately gram- rods with some gram+ cocci (like peptostreptococcus), you can conclude that the likely pathogen(s) involved are:
B. oral anaerobes
An 18-year old female comes into your office complaining of a "sinus headache". Upon further examination, you find that her sinuses are inflammed and filled with pus. She goes on to tell you that she just had her wisdom teeth pulled a week ago. What is the most likely pathogen involved?
A. Actinomyces israelii
An 18-year old female comes into your office complaining of a "sinus headache". Upon further examination, you find that her sinuses are inflammed and filled with pus. She goes on to tell you that she just had her wisdom teeth pulled a week ago. You take a sample of the pus, stain it and view it under a microscope. You find gram+ filamentous rods that resemble fungi and look "hairy", and yellow granules that resemble sulfur. What is her diagnosis and what pathogen(s) are involved?
A. Upper respiratory tract infection, Actinomyces israelii
A 19-year old boy who claims to have pretty good dental hygiene is consistently having problems with getting cavities. He denies eating sweets and hates soda. He brushes twice a day, in the morning and at night, and flosses throughout the day in between meals. You ask him if he's had any recent surgeries. He tells you that he just had a tooth extraction a few months ago. What is the most likely cause of these newly-formed cavities?
D. Viridans streptococci
A 27-year old female otherwise healthy individual has developed a mild case of endocarditis following a recent tooth extraction. You take a sample of her blood and identify gram+ cocci. You then do a blood culture and perform a catalase test. It comes back negative. What would be the most likely pathogen involved?
C. Viridans streptococci
A 35-year old HIV patient comes into your office and presents with oral thrush, and inflammatory patches on their esophagus. You take scrapings of the infected mucosa to view them under a microscope. You find oval cells with hyphae and germ tube formation. What is the most likely involved pathogen?
D. Candida albicans
A woman brings her 6-month old baby into your office, because she has been crying uncontrollable, is fussy and irritable, and has not been feeding well. The woman is extremely worried and goes on to tell you that she noticed that whenever she tried to touch the baby's right ear, she would pull away or cry even more. The woman says that the baby has received all of the necessary vaccines to date, including Hib. You exam the baby's ears and find that the tympanic membrane of the right ear is swollen. You then perform a needle aspiration and find pus formation with the otitis media. What is the most likely pathogen involved?
B. Streptococcus pneumoniae (H. influenzae not likely because the baby has been vaccinated with Hib)
Why are infants more susceptible to middle ear infections than adults?
shortness and pliancy of infants' eustachian tubes
You perform a needle aspiration on an infant who is believed to have a middle ear infection (otitis media). Upon further examination in a lab, you find small, gram- coccobacillus organisms with a capsule. The organisms require X and V factors to grow in lab and demonstrate "satellite growth". What is the causative agent?
A. Haemophilus influenzae
What are the the most important virulence factors involved in Streptococcus pyogenes infection of the upper respiratory tract and what are their mechanisms of action?
hyaluronan capsule - evasion
protein F - adhesion
M protein - evasion
lipoteichoic acid - toxin
streptolysin O and S - beta-hemolysis, tissue damage
A 5-year old girl is brought into your office and presents with "strawberry tongue", pharyngitis with pus on her tonsils, and a rash that spreads from her mouth and face to her trunk and extremities. What is her diagnosis?
E. Scarlet fever
What is the most common sequelae associated with group A streptococcus infection?
acute glomerulonephritis
What is the sole virulence factor for Corynebacterium diphtheriae?
diptheria toxin
All of the following are true of diptheria toxin (DT) except:
B. Holotoxin is taken up by receptor-mediated pinocytosis (taken up via receptor-mediated endocytosis)
What is the enzymatic mechanism of action for diptheria toxin (DT)?
ADP-ribosylation of elongation factor 2
True or false. The synthesis of diptheria toxin (DT) is positively regulated by iron.
False, the synthesis of diptheria toxin (DT) is negatively regulated by iron.
You're examining an isolation from a throat swab and find gram+ club-shaped rods that resemble "Chinese letters". What organims is this?
C. Corynebacterium diptheriae
Which virulence factor allows Bordetella pertussis to colonize in the upper respiratory tract?
filamentous hemagglutinin
_____ is the major virulence factor of B. pertussis.
pertussis toxin
What is the enzymatic mechanism of action for pertussis toxin (Ptx)? What other toxin is this mechanism similar to and how does it differ?
ADP- ribosylates Gi protein, double negative action (inhibits an inhibitor > cAMP production via AC); similar to cholera toxin (CT) and it differs by inhibiting Gi which leads to cAMP production via AC, while CT stimulates Gs and leads to cAMP production via AC
What is the mechanism of action for invasive adenylase cyclase and what does it require?
enters cells and directly stimulates cAMP production; calmodulin
True or false. The pertussis toxin (Ptx) receptor is homogenous.
False, the pertussis toxin (Ptx) receptor is heterogenous.
_____ responds to environmental signals (increase in temperature) by phosphorylating _____, which then activates transcription of genes for filamentous hemagglutinin and toxin production.
BvgS; BvgA
A 3-year old boy is brought into your office because his mother is concerned about a persistent, paroxysmal cough that the child has had for the past week. The teachers at the boy's preschool are concerned that whatever he has may be highly contagious and has forbidden that he return until he is cleared by his pediatrician. You take a deep nasopharyngeal swab for culture on a Charcoal blood agar (with antibiotics) media. It takes about 3 days for the culture to grow. You also examine the sample under a microscope and find gram- coccobacillus organisms. What is the most likely diagnosis and what pathogen is involved?
