Micro Basics (Doesn't cover last 2 lectures) Flashcards
What immunoglobulins are present in mucus?
IgA
What are the common causative agents of acute bronchitis?
Influenza (a & b); parainfluenza, RSV, rhinovirus, coronavirus
What is the most common causative agent of bronchiolitis?
RSV
What is the most common causative agent of community-acquired PNA?
S. pneumonia
What is a common PNA causative agent in HIV-positive patients?
Pneumocystis jirovecii
What is the most common causative agent of hospital-acquired PNA?
S. aureus
What are two organisms associated with PNA in cystic fibrosis patients?
Burkholderia and Psuedomonas aeruginosa
Your patient recently stayed in a hotel and now has PNA. What organism comes to mind?
Legionella
What constitutes a good sputum sample?
From lower respiratory tract
Neutrophils present in good numbers
10 or fewer squamous epithelial cells per low-power field (if shown a picture, look like fried eggs - don’t want many eggs.)
What are some virulence factors of Legionella?
Production of biofilms;
Chlorine resistance;
Pore-forming toxin
Your patient has PNA symptoms and is an HVAC tech. What are some things the lab needs to take into consideration when culturing the sample you send?
Legionella needs buffered charcoal yeast extract with L-cysteine and iron.
You suspect Legionella. What’s the best way to dx?
Urine antigen test
What will be seen in a culture positive for Legionella?
Faintly-stained, Gram-negative bacilli; use silver stain or direct antibody fluorescence to better visualize. Ground glass appearance after ~5 days.
Which organism is associated with deer fly/tick bites (or with animals bitten by deer flies/ticks)?
Francisella tularensis
What special media is used for culture of Francisella tularensis?
Cysteine heart agar
What are some virulence factors for F. tularensis?
Capsule
LPS that evades recognition by our TL4s
Replication that can occur in various cell types
Hematogenous spread
What organism is associated with birthing of goats, sheep, and cows, or the veterinarians/farmers that are around them?
Coxiella burnetti
What organism is associated with ingestion of unpasteurized milk?
Coxiella burnetti
What organism causes Q fever?
Coxiella burnetti
What are some virulence factors associated with Coxiella burnetti?
Forms spore (stays stable in the environment for long periods of time)
Resists digestive enzymes and the acid pH in phagolysosomes (replicates inside the phagolysosomes)
Patient has chest CT with patchy areas of necrotizing consolidation and cavitating nodules. Culture shows a pink, branching organism on acid-fast stain. It looks beaded/chalky on Gram stain. What is a likely organism?
Norcardia asteroides, a type of partially-acid-fast, aerobic actinomycite that causes disease in immunocompromised patients (often fatal).
Patient presents with fever, cough, and weight loss. Culture shows a red-staining bacilli on acid-fast stain. What is the likely organism?
Mycobacteria tuberculosis, an acid-fast bacilli.
Word association: “Rough, buff, tough” colonies
Mycobacteria tuberculosis
College-aged patient presents with PNA-like symptoms but has no fever. What organism do you suspect?
Chlamydia pneumoniae
Your patient lives with one thousand parakeets and has fever with a dry cough. What organism/disease do you suspect?
Chlamydophilla psittaci - causes psittacosis
You have a young patient with very mild PNA during the summer. What organism do you suspect?
Mycoplasma pneumoniae (not S.pneumo)
Which influenza virus is associated with epidemics and severe disease?
A
What type of antigenic variation is associated with small outbreaks within a community?
Antigenic drift: occurs because of lack of proof-reading mechanism in RNA replication
What type of antigenic variation is associated with epidemics/pandemics?
Antigenic shift (occurs when two strains combine and re-assort within a cell)
