Microbiology Flashcards
Swollen, cherry-red epiglottis – most common cause?
Epitglottitis - fever, sore throat, dysphagia, drooling, airway obstruction with stridor
most commonly caused by H. flu
Hib vaccine now part of routine vaccination schedule in first few months
What is Strep pneumo’s major virulence factor?
outer polysaccharide capsule
prevent phagocytosis and removal/neutralization with antibodies takes away pathogenicity
Gram +, catalase -, beta hemolytic, bacitracin resistant? How to prevent?
Group B Strep
causes neonatal sepsis, pneumonia, meningitis
universal prenatal screening for group B by maternal vaginal and rectal culture at 35-37 weeks
culture-positive women take ampicillin prophylaxis
penicillin used to treat
Which bacteria are found in soil and form spores? Other spore-forming bacteria?
Spore-forming in soil:
Bacillus anthracis, Clostridium perfringens, Clostridium tetani
Spore-forming:
Bacillus cereus, Clostridium botulinum and difficile, Coxiella burnetii
Mucicarmine stain?
Cryptococcus neoformans
capsule stains red
Cold hemagluttinins?
Mycoplasma pneumoniae
cross-reacting antibodies between M. pneumo and RBCs – can cause mild anemia that resolves with resolution of infection
What stains red in an acid-fast stain?
mycolic acids in the cell walls of Mycobacteria and Nocardia
NADPH oxidase deficiency leads to vulnerability to which organisms?
catalase-positive organisms:
- Staph. aureus
- Pseudomonas
- Serratia marcescens
- Nocardia
- Aspergillus
Barking cough, dyspnea, and recent history of URI? Most common cause?
viral laryngotracheitis (croup) most common cause is parainfluenza virus
croup:
- obstruction of inspiration (inspiratory stridor)
- obstruction of expiration (barking cough)
High fever, watery diarrhea, headache – sputum gram stain with many neutrophils and no bacteria?
Legionella pneumophila – Legionnaire’s disease!
hyponatremia
need to silver stain (gram negative but doesn’t often not detected on gram stain)
Grows with hematin (X factor) and NAD+ (V factor) and can cause fever, malaise, swollen right knee after history of otitis media? Major virulence factor is?
H. flu
septic arthritis
major virulence factor is antiphagocytic capsule
needed for pathogenicity
Strep. pneumo – bile solubility? Hemolysis pattern?
Alpha-hemolytic bile soluble (cannot grow in the presence of bile)
Fungus that forms small ovoid bodies within macrophages and causes cough, low-grade fever, and hepatosplenomegaly? Associated with what type of transmission?
Histoplasmosis
(Histo “hides” in macrophages)
Bird or bat droppings contain spores that are inhaled
What infectious agent is associated with progression to brochiectasis?
Allergic bronchopulmonary aspergillosis (ABPA)
due to Aspergillus fumigatus
causes transient recurrent pulmonary infiltrates and eventual proximal bronchiectasis
What CD4 count is normal? What CD4 count puts you at risk for Pneumocystic jiroveci? What is the most common cause of pneumonia above that?
CD4 > 500 considered normal
CD4 < 200 puts you at risk for opportunistic P. jiroveci infection
most common cause of community-acquired pneumonia in immunocompetent host is Strep. pneumo