Wed Respiratory infectious disease Flashcards
two main obstacles that bacteria has to avoid in order to colonize the respiratory tract
overcome the mucus (would make them go to the stomach)
overcome phagocytosis
what cells in the respiratory tract produce mucus
goblet cells
common causes of bacterial sinusitis
s. pneumo, H. flu
adhesion molecule that rhinoviruses use to infect the cells lining the nasal passages
binds to ICAM-1 on the cells
(intercellular adhesion mollecule
details of a rhinovirus
Class IV RNA (ss+)
icosahedral
nonenveloped
picornavirde
the one virus that causes common colds that is a DNA virus
adenovirus
3 most common organisms in conjunctivitis
h. flu
Adeno
S. pneumo
common antibiotic prescribed for bacterial sinusitis
amox
azith
What bacteria is alpha hemolytic and optochin sensitive
strep pneumo
what are the virulence factors associated with s. pyogenes binding to mucosal epithelial cells
what is the capsule made out of?
M protein, lipoteichoic acid, fibronectin-binding protein (protein F)
hyaluronic acid - prevents phagocytosis by macrophages
group A and group B beta hemolytic strep
what antibiotic can you introduce to cultures in order to tell them apart
group A - strep pyo (bacitracin sensitive)
group b - strep agalactiae (bacitracin resistant)
classification of diptheriae
gram +
bacilli
non spore formin
non motile
how do you get scarlet fever
Sx?
certain groups of s. pyo that secrete exotoxins (ssa, speA, speC)
scarlet rash with sandpaper-like texture, strawberry tongue, cercumoral pallor
croup
low fever, barklike cough, begins with common cold like Sx
RSV
what is it
what do you see histiologically
respiratory syncytial virus
it is a Paramyxovirus
(PaRaMyxo - parainfluenza (croup), RSV, Measles, Mumps)
see multinucleated cells
What does rhinovius bind to
icam -1
parainfluenza virus uses what to infect
causes what disease
viral fusion F surface proteins for fusion and causes multinucleated giant cells in croup
Inhaled through aerosols. Infects the larynx mucosa via contact of the viral hemagglutinin (HA) envelope protein with sialic acid on cell surfaces (leads to endocytosis). The viral neurominidase (NA) envelope protein is important for cleaving HA bound to sialic acid, this permits viral spread.
coxsackie a and b
how do you get it
A: Hand-foot-and-mouth disease can be seen as vesicles on the hands, feet, and mouth and typically occurs in young children. herpangia - fever, sore throat, red oropharynx vesicles
Coxsackie B virus is associated with 50% of cases of viral myocarditis. pleurodynia (pain when breathing)
fecal oral
what are you thinkning if you see conjuctivitis with the common cold
adenovirus
major virulence factors of strep pyo
streptokinase (converts plasminogen to plasmin fibrinolysis), M protein (resists phagocytosis), hyaluronidase (breaks down connective tissue), DNase (breaks down DNA).
what are you thinking if you see erysipelas
aka st. anthony’s fire.
caused by group A strep (strep pyo)
what strep is bacitracin sensitive? what is resistant
Strep pyo - sensitive
Strep agalactiae - resistant
biochemical factors that can aid in diagnosis of moraxella
hydrolyzes tributyrin, produces DNase, reduces nitrite and nitrate, does not ferment sucrose, glucose, maltose, or lactose.
Tx - augmentin (95% of cases are beta lactamase positive)
what does diphtheria toxin do
it is an AB toxin that ADP rybosylates EF-2 and prevents protein synthesis in all cells
general bacterial characteristics of diptheriae
gram + rod, aerobic, black colonies on potassium tellurite
may look like chinese characters under the microscope
clinical presentation of diphteriae
pseudomembrane on the nasopharynx. systemic = myocarditis and polyneuritis
what is meant by quellung +
bacteria has an antiphagocytic capsule
general identifiers of strep pneumo
gram (+) diplococcic, α-hemolytic, catalase (-), susceptible to optochin (virdans is resistant)
what type of H flu has a capsule
type B
types with capsule are more likely to go systemic.
non typable are usually just local infections
H flu can go systemic much more easily if you don’t have this organ
spleen
the spleen is where opsonized bacteria get digested
what bacteria has an IgA protease
H flu
general bacterial characteristics of H flu
gram -, requires hemin (x factor) and NAD (V factor) on chocolate agar, + Quellung test
respiratory syncytial virus virulence factors
g surface protein important for attachment to host cells. F surface protein causes infected cells to fuse (aka form syncytia)
respiratory syncytial virus presents as
bronchiolitis, pneumonia in children
common cold in adults with weezing like asthma
worldwide outbreaks occur every winter
what do you give for severe cases of RSV
ribavirin
virulence factors of influenza C
HA (hemeagglutinin)
NA neuroaminidase
