Micro: Lower Respiratory Tract Infections Flashcards
What are the organisms that make up the normal flora of the Lower Respiratory Tract ?
PSYCH ! Trick question, the LRT is a sterile environment and should not have a colonization by bacteria.
Infections in the LRT are cause by Virus, Fungi and Bacteria. Where do bacteria that cause infections usually come from ?
Typically from upper respiratory tract infections --> LRT Ear Infections/ URT S.pneumoniae H. Influenzae Moraella
Mycoplasma pneumoniae
In acute brochitis, what kind of fever will you see ?
Either none or a very low grade. If it is high grade, most likely pneumonia not bronchitis.
What must be excluded in order to come to a diagnosis of Acute Bronchitis
COPD
Pneumonia
Define pneumonia
Inflammation of the lungs accompanied by fluid filled alveoli and bronchioles
Most common cause of death due to infection in the elderly
How are pneumonias classified ? (3)
Causitive agent
Where acquired (Community, Nosocomial)
Typical v. Atypical (Productive cough)
What is the #1 cause of typical pneumonia ?
S. pneumoniae
Describe the signs and symptoms of an Typical Pneumonia
abrupt onset
Fever, chills, Congestion SOB
PRODUCTIVE COUGH (the hallmark)
Describe the Lab diagnostics for S.pneumoniae
Gram + Catalase - Pairs of chains Alpha Hemolytic Optochin Sensitive
What is the most important virulence factor for S.pneumoniae ?
The Capsule (allows for adhesion)
List other virulence factors for S.pneumoniae besides the capsule
Adhesin (for adhesion)
IgA protease (Breaks down IgA. This is very important in the lungs
Pneumolysin (lyses ciliated epithelial cells)
What may predispose someone to pneumococcal pneumonia ?
Previous Viral infection Alcoholism (this is not specific, more telling for Kleb) Children Elderly SPLENECTOMY NON_IMMUNIZED !
How would you describe the productive cough associated with S.pneumoniae ?
Rust Colored Sputum
What would you see in microscopy with S.pneumo ?
Gram + cocci, and NUMEROUS PMN’s (neutrophils)
PPSV23
AKA Pneumovax, 23 most common capsule serotypes –> Adult !!
PCV13
Pneumococcal conjugate vaccine
Children 2 moths - 59 months
What is the most important virulence factor for Klebsiella pneumonia >
Capsule
Describe the productive cough associated with Kleb Pneumoniae ?
Current Jelly Sputum (due to blood and capsule)
Is Klebsiella CAP or HAP ?
BOTH !
Is S.pneumos CAP or HAP ?
CAP
Being hospitalized and on a ventilator are big risk factors for Kleb pneumoniae . What is the another huge risk factor ?
Alcoholism
Why is Kleb pneumoniae associated with higher mortality than pneumococcal pneumonia ?
Causes necrosis of the lung tissue.
LPS can be released (Gram -) leading to shock.
Describe the Lab diagnostics for K. pneumonia
Gram- rod
Lactose fermenter ( Lac + leads to purlple discoloration of agar due to acid)
Indole - ( not e.coli)
Grows on MacKonkey Agar
DOC for K.pneumoniae
Gentamicin
Ciprofloxacin
Why may K.pneumo be difficult to treat ?
Carbapenem resistence (contains a carbapenamase)
Describe the lab finding for H.influenzae
G- coccobacillus
Grows on Chocolate Agar (Factor V(NAD)and X)
Although G-, it will not grow on MacKonkey.
Often a normal fluora of the URT.
List the main virulence factors for H.influenzae
CAPSULE
LPS (endotoxin, can cause shock)
Adhesisn
Who is at risk for H.influenzae ?
Elderly
Smokers
COPD
Describe the lab diagnostics for S.aureus
G+ coccus
Catalase and Coagulase +
Describe the productive cough caused by S.aureus
“Salmon Pink” sputum
How is S.aureus typically disseminated to the LRT ?
Aspiration Hematogenous (bacteremia or endocarditis
What is a typical area of the lung for S.aureus to infect ?
Pleural cavity (Empyema = pus filled pleural cavity) Abscesses (causes or inhabits ?)
Suppose you encounter a patient with severe hemoptysis and shock. You notice Gram + cocci on microscopy. What organism do you suspect
CA- MRSA
What will you see on gram stain with organisms that cause atypical pneumonia ?
NOTHING !
Most eitehr do not have a gram reaction or they are intracellular pathogens.
mycoplasma pneumoniae is CAP or HAP ?
CAP
Pneumonia due to mycoplasma pneumonia is also known as ..
Walking pneumonia (#1 cause)
Why does mycoplasma not show on gram stain ?
No cell wally !
T or F: Mycoplasma is encapsulated
True !
what virulence factor allows mycoplasma to bind to ciliated epithelial cells ?
Adhesin
What will you see on microscopy of aspirate from a lung with mycoplasma infection ?
large # of PMN’s w/o organisms !
What are the characteristics associated with mycoplasma ‘walking pneumonia’ ?
Non- productive, persistent cough.
Excessive sweating !*
Igm for Mycoplasma and RBC’s that are diagnostic for the organism are also known as..
Cold Agglutinins
Why will you not see Chlamydophila pneumonias on gram stain ?
It is an intracellular pathogen !
It is gram - however, so if it were to be out of the host organism, you would see it as a pink blot.
What is the infectious stage of Chlamydophila ?
Elementary body
What is the replicative form of Chlamydophila ?
Reticulate body
What would you see upon microscopy of a patient suspected of having chlamydophila ?
Large amount of PMN’s but no organisms
What is treatment for Chlamydophila ?
Azythromycin
Arythromycin
Doxycycline
(Treatment for G-)
Chlamydophila psittaci cause what disease ?
Parrot fever
Although it does not show up on gram stain, how could we classify Legionella ?
Gram - (does not gram stain well however)
What two building structures are associated with legionella ?
water cooling towers and air conditioning units.
Besides, not gram staining well. Why would yu not see legionella on gram stain ?
Intracellular bacteria
What cells does legionella infect within the body ?
Alveolar macrophages
how is legionella transmitted ?
Aerosolized droplets (really likes h20)
Describe the signs and symptoms of legionella infection
ABRUPT ONSET of fever Pleurisy Chills Myalgia Dry Cough --> Hyponatremia
Complications with liver or kidneys are common
Patients at risk for legionella include:
Smokers
COPD
Elderly
RENAL TRANSPLANT or DIALYSIS !
What media will Legionella grow on ?
Buffered Charcoal Yeast Extract. (Iron and cysteine salts)
In What body fluid can you detect legionella antigen with fluorescence ?
Urine.
What are the common causes of nosocomial pneumonia ?
Pseudomonas aeruginosa
S.aureus
H.influenzae
Enterics (due to aspiration)
Enterobacter
Kleb
E.coli
SerratiaIn cystic fibrosis, what bacteria colonizes the lung prior to pseudomonas ?
S. aureus
Pseudomonas colonizes by 5 yo
What are some key signs of pseudomonas infection
copious green sputum , grape smell
Hot tub folliculitis also caused by pseudomonas.
Why is pseudomonas difficult to treat ?
resistant to many antimicrobials
How do most anaerobes get into the lungs to cause pneumonia ?
Aspiration of gastric material into the respiratory tract.
What are the major classes of anaerobes that are found in aspiration pneumonia ?
Bacteriodes and Fusobacterium
What do bactericides and fusobacterium typically cause within the lung ?
Necrotizing lung disease
Lung abscess and empyema (pyothorax)
Describe the productive cough associated with anaerobes
Copious amounts of foul smelling sputum.
What is the DOC for anaerobic bacteria ?
Metronidozole for 2-4 months.
Bacillus anthrax is gram + or gram - ?
Gram +
describe the shape of bacillus anthrax
Boxcar shaped
How is anthrax transmitted ?
Inhalation of endospores
what is the most important virulence factor associated with anthrax ?
Anthrax toxin
Describe the course of inhalation anthrax infection
Early: Sore throat, mild fever, myalgia and cough
After a few days : Severe coughing, NV, Lethargy, Shock and Death.
How would you treat inhalation anthrax
Penicillin, Ciprofloxacin, doxycycline. Prayer.
Yersinia pestis is less affectionatel known as ..
PLAGUE !
What kind of gram stain organism is yersinia pests
Gram -, Coccobacillus.
Describe the productive cough seen in Yersinia infection ?
Frothy bloody sputum
Fever, chills, cough, difficulty breathing.
What would you seen on microscopy with stained Yersinia samples ?
Bi-polar coccobacilli (Safety pin staining, darker at the ends)
What is the treatment for yersinia pestis?
Streptomycin/Gentimycin
Tetracycline/Doxycycline
Chloramphenicol
What organism is responsible for Q fever ?
Coxiella burnetti
Why will you not see Coxiella on gram stain ?
Although it is gram - , you will not see it since it is an intracellular parasite.
What are the primary carriers of Coxiella ?
Cattle, Sheep and goats.
How is Coxiella transmitted ?
Inhalation of contaminated dust
Ingestion of unpasteurized milk
Working in a slaughterhouse farm or vet office
Describe the symptoms associated with coxiella
acute onset, severe headache, non-productive cough, muscle pain and fever.
What animal is Francisella tularensis associated with ?
Rabbitts –> Tularemia
Will you see Francisella on gram stain ?
No, it is an intracellular pathogen (although, it is gram -coccobacillus)
What culture media will Francisella grow on ?
BCYE and Cysteine Glucose blood agar !
TOC for francisella ?
Streptomycin
