Diebel: Causative Microorganisms of LRT Infections Flashcards
How many RNA segments do influenza A and B have vs. C?
And B- 8
C- 7
How are influenza C infections different in terms of sxs?
Much less virulent than A and B and many infections are ASYMPTOMATIC
Which influenza viruses have NO antigenic shifts?
B and C ( no animal reservoir)
Which influenza viruses are unresponsive to amantadine or rimantadine?
B and C
Which influenzas go through antigenic drift?
ALL
Which influenza exhibits antigenic shift and drift?
Type A
What is the clinical presentation of influenza?
Common cold and flu that can lead to
SECONDARY bacterial pneumonia
Describe the pathology of the influenza virus.
Aersols> infects the larynx mucosa> Viral HA protein contacts SIALIC ACID on cell surfaces> endocytosis> NA cleaves HA bound to sialic acid> viral spread
How does influenza cuase damage?
Viral replication in host cells>
death of host cell>
tissue damage/ disease
IR produces IL-1 and IFN y
How do you diagnose influenza?
pt sxs
How do you confirm influenza?
Rapid antigen test on nasophyrngeal swab
Culture swab to detect HA type and RBC agglutination test
What vaccines are available for influenza?
Inactivated type A and B virus HA and NA ags
What is the clinical presentation of bordatella pertussis?
Whooping cough
What is the pathogenesis of pertussis?
Airborne transmission>
adheres to CILIA of RT via FHA>
release of toxins>
disease
What is the pertussis toxin?
AB toxin> inactivates Gi proteins> increase in cAMP> increase in lymphoctye numbers impairs phagocytosis
What is tracheal cytotoxin?
Kills epithelial cells and impairs mucous clearance
What are the three stages of whooping cough?
- Catarrhal (1-2 weeks)
- Paroxysmal ( 3rd week to 2 mos)
- Recovery (2-3rd month)
What sxs are associated w/ the catarrhal stage?
flulike sxs
highly contagious
What sxs are associated with the paroxysmal stage?
Coughing bouts w/ whooping inspiration
What characterizes the recovery stage?
coughing subsides
Gram - coccobacillia
Bordet gengou medium
Bordatella pertussis
How do you prevent whooping cough?
DTaP
How do you tx whooping cough?
Erythromycin for STAGE 1 only
What can strep. agalactiae cause?
Neonatal pneumonia a day after birth
How does strep. agalactiae colonize?
Carried in the maternal GI tract>
obstetric complication>
colonization of neonate
Neonatal pneumonia caused by…
Gram +
Beta hemolytic
Bacitractin resistant
strep. agalactiae
How do you treat strep. agalactiae?
Penicillin G
What microorganism most commonly affects young people that live in close quarters?
Mycoplasma pneumoniae
What is the microorganism: No cell wall Marked pleomorphism Resistant to Beta lactam antibiotics NO gram stain
Mycoplasma pneumoniae
What microorg causes tracheobronchitis and atypical pneumonia?
Mycoplasma pneumoniae
This bacteria adheres to the respiratory epithelium, inhibits ciliary motion and destroys mucosa. B cell response to the infection causes IgM cold agglutinatinins.
Mycoplasma pneumoniae
How do you treat Mycoplasma pneumoniae?
Erythromyacin
Tetracycline
Chlamydia pneumoniae (TWAR) most commonly infects what population?
Young adults
How does TWAR usually present?
Atypical pneumonia
What is the pathogenesis of TWAR?
Obligate intracellular parasite> enters URT> phagocytosed by mphages> lymphocytes infiltrate> pulmonary edema, necrosis and hemorrhage
What is the infective form of TWAR?
EB
How do you diagnose TWAR?
Giemsa stain to visualize INTRACYTOPLASMIC inclusions
How do you treat TWAR?
Doxycyline
What respiratory disease can s. Aureus cause?
Pneumonia w/ cavitations
How does S. Aureus cause Pneumonia?
Bacteria colonize nasopharynx>
neutrophils localize to site of infection>
purulent abscess forms>
Pneumonia
How does s. aureus evade host defenses?
Protein A
coagulase
hemolysins
leukocidins
A bacteria that has gram + clusters, catalase + and coagulase + is?
s. aureus
How do you treat pneumonia caused by s. aureus?
penicillinase resistant penicillins
vancomycin
What is an important cause of community acquired pneumonia in elderly smokers?
Legionella pneumophillia
What is the clinical presentation of legionella pneumophillia?
Legionnaire’s disease (atypical pneumonia)
How does legionella cause pneumonia?
Inhaled> adheres to RT via pili> phaygocytosed by alveolar mphages> mphages secrete neutrophil attractants> neutrophils arrive from microabscess> severe atypical pneumonoia
Silver stain, charcoal yeast extract, and Urinary antigen are used to detect…
Legionella
How do you treat legionalla pnepumophila?
Erythromycin
What causes pneumocystis pneumonia?
Pneumocystis jirovecii
What is the pathogenesis of PCP?
cyst inhaled in childhood>
stays latent in lungs>
mild/asymptomatic pneumonia
How do you diagnose PCP?
silver stain
cysts form dark oval bodies
How do you treat PCP?
TMP-SMX or pentamide
What bacteria can cause pneumonia in immunocompromised pts and resembles TB in presentation?
Nocardia asteroides
What bacteria causes a pneumonia w/ cavitations that can lead so abscesses in the kidneys and brain?
Nocardia asteroides
What bacteria is: gram + aerobic beaded filaments w/ a filamentous growth weakly acid fast?
Nocardia asteroides
How do you treat nocardia asteroides?
TMP SMX
drain the surgical abscesses