28 - Bacterial Infections of the Lower Respiratory Tract I Flashcards
1
Q
What is the difference between lower respiratory and upper respiratory infections?
A
LRIs are less common than URI, but more severe
2
Q
What are the different types of bacterial LRT infections that you can get?
A
- Laryngitis
- Tracheitis
- Epiglottitis
- Pertussis
- Bronchitis
- Bronchiolitis (mainly viral)
- Pneumonia
3
Q
What is pertussis?
A
An infection that involves the trachea and bronchi and is commonly called “whooping cough”
4
Q
What is pneumonia?
A
Inflammation of the lung parenchyma with fluid accumulation in the alveoli which blocks effective gas exchange
5
Q
How does the airway defend against pathogens?
A
Ciliated epithelium
- Cilia beat 1000/minute
- Coated in mucous
6
Q
How much ciliated epithelium is there in the airway?
A
- 80% of the conductive airway
- 150-300 cilia per cell
7
Q
What is the mucociliary escalator?
A
Movement of mucous & trapped particles up the bronchioles, bronchi, and trachea to be swallowed
8
Q
When will you see impaired airway defense?
A
- Viral infections
- Tobacco smoking
- Alcohol consumption
- Narcotic use
9
Q
What is the goal of pathogens?
A
Circumvent the mucociliary escalator and avoid being swallowed to cause disease
10
Q
What is bacterial pneumonia?
A
Inflammation of the lung as a result of a bacterial infection
11
Q
What are the general features of bacterial pneumonia?
A
- Fever
- Malaise
- Cough
- Pleuritic chest pain
- Dyspnea
- Sputum production
- Crackles
12
Q
Why is the sputum production a SIGNATURE FEATURE?
A
The appearance
- Rust-colored
- Currant-jelly appearing
- Purulent
- Mucoid
- Foul-smelling
- Scant/watery
13
Q
Bacterial pneumonia is often secondary to ________________.
A
A viral respiratory tract infection
14
Q
What populations of people are at an increased risk of developing bacterial pneumonia?
A
- Comorbidities: Heart disease, diabetes, lung disease / cancer, immunosupression
- Age extremes: infants & > 50 yrs
- Smoking, alcohol, narcotics (effects on mucociliary escalator)
15
Q
What is the pathogenesis of bacterial pneumonia?
A
- Bacteria enter small airways or alveoli and grow in rich lung environment
- The bacteria will cause damage to the lungs using their virulence factors
- Local effects due to inflammatory immune response to bacteria
16
Q
What are the common virulence factors seen in bacterial pneumonia?
A
- Capsules
- Intracellular growth
- IgA protease
- Exotoxins
- LPS (endotoxin)
17
Q
What will the local effects due to inflammation lead to?
A
- Irritation
- Pain
- Dyspnea (SOB)
18
Q
What will you find accumulating in the lungs in bacterial pneumonia?
A
- Fluid
- Bacteria
- Neutrophils
- Fibrin
19
Q
What do we call this accumulation in the lungs?
A
Consolidation
20
Q
How will this appear on an x-ray?
A
The consolidation leads to opacity on a chest x-ray (CXR)
21
Q
Why is consolidation problematic?
A
The lungs become full of liquid, so full they aren’t expanding very well
22
Q
How will the lungs feel if you palpate them?
A
They will feel full
23
Q
What is a “lobar pattern” on a CXR?
A
Typical - caused by…
- Streptococcus pneumoniae
- Staphylococcus aureus
- Haemophilus influenzae
- Most Gram-negative bacteria
24
Q
What is a “patchy pattern” on a CXR?
A
Atypical - caused by…
- Mycoplasma pneumoniae
- Chlamydophila pneumoniae
- ***Legionella pneumophila
25
What is the difference between lobular pneumonia and bronchopneumonia?
- Lobular (alveoli are filled with fluid)
| - Bronocho (alveoli are filled with pus and cavities form)
26
How else can you distinguish between typical and atypical?
Symptoms or labs
27
What are the common symptoms of typical pneumonia?
- Sudden onset
- Productive cough
- Bloody sputum
- High fever (103-104)
- Consolidation frequent
28
What are the common symptoms of atypical pneumonia?
- Gradual onset
- Nonproductive cough
- Scant, watery sputum
- Low fever (less than 103)
- Rarely consolidation
29
Which type, typical or atypical, will raise the RBC count?
Typical ONLY
Atypical will not have elevated levels
30
What is the most common cause of typical pneumonia?
Streptococcus pneumoniae
31
What is the most common cause of atypical pneumonia?
Mycoplasma pneumoniae
32
Is Legionella pneumophila typical or atypical?
It does NOT fit into this scheme - It causes a toxic pneumonia… More to come on this
33
What is damaged in lobular pneumonia?
- Damage to alveolar wall
| - An entire lobe is affected
34
What complications can arise from pneumonia?
- Pleural effusion
- Hematologic effects
- Chronic complications (of chronic pneumonia)
35
What is a pleural effusion?
Sterile effusion in the pleural space
36
What hematologic effects will you see?
- Anemia with chronic pneumonia
- Disseminated intravascular coagulation
- Thrombocytopenia
37
What are the complications of chronic pneumonia?
- Low arterial pO2
- Weight loss and muscle atrophy
- Bronchiectasis
38
What is bronchiectasis?
- Localized, irreversible dilation of the bronchi and bronchioles caused by muscle and elastic tissue damage
- Can permanently damage the lung
39
What is aspiration pneumonia?
Introduction of foreign material into the bronchial tree (usually fluid) - it is a secondary bacterial pneumonia
Saliva, food, nasal secretions
40
Why is this aspiration problematic?
- Carry bacteria in
- Also “dilute out” your lung immunity (surfactant, immune cells, other protective factors)
- Large volume of liquid dilutes / prevents proper host response / clearance
41
What is aspiration pneumonia commonly associated with?
- Alcoholics
- Coma patients
- Stroke patients
When alcoholics pass out, they can inhale vomit
42
What is community acquired pneumonia?
Any pneumonia not acquired in a healthcare setting
43
What is hospital acquired pneumonia?
Nosocomial, acquired in a health-care setting (HAP, HCAP)
44
What is HAP typically associated with?
- Immunocomprimised
- Ventilator use (VAP)
Even if you’re not immunocompromised by labs, the ventilator itself can be an easy pathway for bacteria to enter the lungs
45
What type of bacteria commonly cause HAP?
Multi Drug Rresistant (MDR) gram-negative bacteria
46
What are the typical causative agent of HAP?
Gram negative
- Pseudomonas aeruginosa
- Escherichia coli
- Klebsiella pneumonia Acinetobacter spp.
- Haemophilus influenzae
Gram positive
- Staphylococcus aureus
- Streptococcus pneumoniae
47
What other diseases will be on your list of differentials when your patient has pneumonia?
All of these conditions can appear as pneumonia
- Hypersensitivity to drugs (can cause edema in the lungs)
- Vasculitis of the lungs
- Lymphoma / carcinoma
- Systemic lupus erythematosus
- Congestive heart failure
48
What else may be relevant to ask your patient that may have pneumonia?
Travel and recent exposures
49
What labs will you order?
- WBC count
- Blood culture
- Sputum analysis
50
What will you see in a WBC test?
Elevated WBC (AKA a “left shift”) typically means there is an increase in immature neutrophils (band cells)
This is typical of bacterial pathogens causing pneumonia
51
What would a positive blood culture indicate?
A severe disease
52
What would a sputum analysis tell you?
>25 PMNs and <10 epithelial cells per 100x field indicates pneumonia
53
What would you test for if you think it is a CAP?
Majority of community acquired cases are treated empirically based on clinical diagnosis and chest x-ray
54
Streptococcus pneumoniae is known to cause what type of pneumonia?
TYPICAL bacterial pneumonia
55
Where does Streptococcus pneumoniae usually colonize?
In the URT (nasopharynx)
56
When Streptococcus pneumoniae causes pneumonia, what do we call the pneumonia?
Pneumococcal pneumonia
57
What type of bacteria are Streptococcus pneumoniae?
Gram positive diplococci in chains
| di= they are paired up
58
What type of hemolysis will you see in Streptococcus pneumoniae?
Alpha hemolysis
Clearing
59
Is Streptococcus pneumoniae catalase positive or negative?
Negative (diagnostically important)
(Catalase - breaks down reactive oxygen species)
This is how it is different from staph
60
How many serotypes are there of Streptococcus pneumoniae?
Many >90
61
Do Streptococcus pneumoniae have a capsule?
Yes - a polysaccharide capsule
62
There are five types of pneumococcal virulence factors that you NEED to know
***
1 - Surface adhesins
2 - IgA proteases
3 - Pneumolysin ***
4 - Teichoic acid and peptidoglycan
63
What does the pneumococcal virulence factor of surface adhesins do?
Colonization in the pharynx
They stick there
64
What does the pneumococcal virulence factor of IgA protease do?
Cleaves IgA antibodies against it, so it prevents the immune system from clearing it
65
What does the pneumococcal virulence factor of pneumolysin do? ***
It is a pore forming toxin that works in...
- COLONIZATION INVASION
- Inflammation
- Complement activation (away from surfaces, so the bacteria is not affected by the complement, but tissue is damaged)
66
What does the pneumococcal virulence factor of teichoic acid and peptidoglycan do?
Inflammation
67
What does the pneumococcal virulence factor - thick polysaccharide capsule do?
It makes the bacteria antiphagocytic
68
What is the clinical presentation of a patient with pneumococcal pneumonia?
- Cough
- Fever
- Dyspnea (SOB)
- Chest pain
- Crackles (crepitations / rales)
- Sputum production
- Rust-colored sputum (***rare but considered indicative)
69
What will pneumococcal pneumonia be proceeded by?
Several days of rhinorrhea
70
What pattern will you notice in the fever pattern?
Abrupt spiking of fever with chills
71
What type of pain will be present?
Severe, pleurtic chest pain
72
How will oxygen levels appear?
Poor oxygenation
73
What happens if untreated?
Untreated, uncomplicated cases should resolve in 7-10 days
74
How do you use laboratory tests to diagnose pneumococcal pneumonia?
- Gram stain sputum
- Cultures of blood and sputum
- Biochemical testing
- Urine collection
75
What biochemical tests can you run on pneumococcal pneumonia?
- Hemolysis = alpha hemolytic
- Catalase = catalase negative (diff. from staph)
- Bile solubility
- Optochin sensitive
76
What does a bile solubility test tell you?
If it is negative (opaque appearing liquid), bacteria are present and blocking the light
If it is positive (clear) bile salts have lysed the bacteria
77
What can you test urine for in pneumococcal pneumonia?
The presence of pneumococcal polysaccharide from the capsule
78
How do you treat pneumococcal pneumonia?
Empiric therapy
- Penicillin for sensitive strains
- Macrolide - azithromycin
- Serious cases- azithromycin plus cephalosporin
79
What would you do to treat pneumococcal pneumonia in severe cases?
Antimicrobial susceptibility testing for directed therapy in severe cases
80
How do you prevent pneumococcal pneumonia?
Vaccination
81
What two options do we have for pneumonia vaccines?
23-valent
(pneumococcal polysaccharide vaccine)
13-valent
(conjugated-pneumococcal vaccine - Pneumococcal polysaccharides conjugated to diphtheria toxoid)
82
How many hospitalizations do we see each year from Pneumococcal pneumonia?
175,000
83
What percentage of CAP and HAP is due to Pneumococcal pneumonia?
36% CAP
| 50% HAP
84
What is staphylococus aureus?
A bacteria that can be considered normal microbiota in some individuals (in the nares), but can also be the causative agent in pneumonia
85
What type of bacteria is staphylococus aureus?
- Gram positive cocci in clusters
86
Will staph aureus test catalaste positive or negative?
POSITIVE
Different from strep
***
87
Will staphylococus aureus test positive or negative for coagulase?
Positive - it can clot blood
Classically used to differentiate from other staphylococci
88
Does staph aureus have virulence factors?
Yes, but you don't need to memorize them
89
What does protein A of the staph aureus do?
Binds to the Fc portion of an antibody, making it ineffective
90
What does the Panton-Valentine leukocidin (PVL) of staph aureus do?
- It leads to severe necrotizing pneumonia
| - It is apore-forming cytotoxin
91
What is Methicillin resistant Staphylococcus aureus?
MRSA
92
Why is MRSA resistant?
- Resistant to all beta-lactam antibiotics, including cephalosporins
93
Is MRSA more virulent/severe than other staph?
- Not necessarily more virulent, just harder to treat
- You don’t necessarily see more severe disease
- They can eventually become more severe because the bacteria has more time to stay in the body and get worse
94
How do you treat staph aureus?
Not MRSA...
- Penicillins/cephalosporins if not resistant
MRSA
- Linezolid (newer 50S inhibitor class) or vancomycin
95
What is a facultative anaerobe?
An organism that can grow in low or high oxygen
96
What is an aerobe?
An organism that needs oxygen to survive
97
Which gram-negative bacteria that is a facultative anaerobe is the number one causer of pneumonia?
Kiebsiella pneumoniae
98
Which gram-negative bacteria that is a aerobe is the number one causer of pneumonia?
Pseudomonas aeruginosa
99
What is unique about these gram-negative bacteria that cause pneumonia?
- They are normal human and environmental microbiota
- They are more likely to be nasocomial (HAP)
- They are common in aspiration pneumonia
100
When patients develop a gram negative pneumonia, what is usually the case?
They have an underlying disease
101
What are the symptoms of gram negative pneumonia?
- Cough
- Purulent sputum
- Fever
- Chest pain
- Dyspnea
- Crackles (crepitations / rales)
- Anaerobic bacterial etiology = fouls smelling sputum
102
Which lobe is typically affected in gram negative pneumonia?
Any lobe may be affected
103
What percentage of patients have pleural effusion with gram negative pneumonia?
25%
104
What is the biggest problem we face in treating gram negative pneumonia?
***
ANTIBIOTIC RESISTANCE
This is a big problem - very important
***
105
What labs will you order to diagnose a gram negative pneumonia?
- Sputum culture
- Gram-staining
- Blood culture (only 20% are positive, but it's worth doing – usually comes up positive in the most severe cases)
106
How do you treat gram negative pneumonia?
- Broad spectrum antibiotics
| - Multi drug therapy
107
Why do we use numerous drugs at once?
- In order to prevent emergent antibiotic-resistant strains
| - Drug synergism: the sum of the parts together is greater then they are alone
108
What "drug cocktail" is given?
Given IV
- Aminoglycoside and beta-lactam (Getamycin/cephalexin, tobramycin/ampicillin)
- Ticarcillin or piperacillin + amikacin (to target Pseudomonas)
109
What type of pneumonia is caused by klebsiella pneuoniae?
Gram negative pneumonia
110
What type of bacteria is klebsiella pneuoniae?
- Gram negative rod
- Non-motile
- Capsulated (mucoid colonies)
111
What will strains of klebsiella pneuoniae typically produce?
Extended-spectrum beta-lactamases
112
How will klebsiella pneuoniae test on a oxidase test?
Negative
```
Positive = purple
Negative = stays a “peachy” color
```
113
Where do we find klebsiella pneuoniae?
Present in the respiratory tract and feces of 5% of normal individuals
114
What is the clinical presentation of a patient with klebsiella pneumoniae?
- Classic lobar pneumonia
- Bloody sputum from necrosis and abscess
- "currant jelly sputum"
You have a necrosis and absess and you’re coughing up part of your lung and blood
115
What virulence factors do you find in klebsiella pneumoniae?
- LPS (exotoxin)
| - A capsule (in 80 of the serotypes)
116
How do you treat klebsiella pneumoniae?
Same way as other gram negative pneumonias
117
What is a concern about the treatment of klebsiella pneumoniae?
There is an increasing rate of antibiotic resistance
Extended-spectrum beta-lactamase (ESBL) producing strains are very problematic
118
What is the mortality rate of klebsiella pneumoniae?
Even with treatment, 50%
119
How do you prevent klebsiella pneumoniae?
- Disinfection of the environment
| - Use of sterile respiratory equipment (plastic that can be thrown out and replaced)
120
What is pseudomonas aeruginosa?
A gram negative bacteria that is another causative agent of pneumonia
121
What type of bacteria are pseudomonas aeruginosa?
- Gram negative rods, flagellated
| - Obligate aerobes
122
Since they are obligate aerobes, do they demonstrate sugar fermentation?
No - negative for lactose or glucose
123
Are pseudomonas aeruginosa oxidase positive or negative?
Positive (= purple)
They convert to purple, showing that they are oxidase positive
124
What type of color pigments will you see in these bacteria?
Blue/yellow-green pigments
125
What does a culture of pseudomonas aeruginosa smell like?
Grapes
126
What are pseudomonas aeruginosa capable of metabolizing?
Capable of metabolizing nearly all known organic compounds (No fermentation, must be aerobic)
127
Where do pseudomonas aeruginosa readily grow?
- Water with minimal nutrients
- Hand soaps
- Dilute antiseptics
128
Will pseudomonas aeruginosa form biofilms?
Yes, most strains will
129
What are some sources of the pseudomonas aeruginosa infection?
Sources of infection include humidifiers, respirators sink traps = contaminated aerosols
130
We know Pseudomonas aeruginosa can cause pneumonia. What else can it cause?
- Septicemia
- UTI’s
- Wound infections
- Meningitis in patients with extensive burns
- Folliculitis
- Ocular infection (contact lenses)
131
What infections can form from Pseudomonas aeruginosa in IV drug abusers?
Endocarditis and osteomyelitis
132
What else can Pseudomonas aeruginosa lead to in cases of sepsis?
Ecthyma gangrenosum lesions
133
What are predisposing factors to contracting Pseudomonas aeruginosa?
- Burns
- Immunosuppressive therapy
- Ventilator use
- Cystic Fibrosis
134
What are the virulence factors of Pseudomonas aeruginosa?
- Toxin A (ADP-ribosylation of EF-2)
- Leukocidin- pore-forming toxin that targets leukocytes
- Phospholipase C – membrane disruption
- Capsule- Anti-phagocytic
- Pyocyanin- blue compound toxic to host cells
- Pyoverdin- fluorescent green iron uptake protein ***
135
Why is pyoverdin, the fluorescent green iron uptake protein important?
***
It can be very indicative of pseudomonas aeruginosa
136
What is the treatment for Pseudomonas aeruginosa diseases?
Two drugs
1 - Antipseudomonal penicillin
(Ticarcillin or piperacillin)
2 - Aminoglycoside
(gentamicin, tobramycin, amikacin)
137
Why is Pseudomonas aeruginosa prevalent in CF patients?
- Impaired mucous secretion = significantly impaired mucociliary escalator
- The majority of CF patients will get this in their life
138
How does this affect pulmonary function?
Strains convert from non-mucoid to mucoid (overproducing extracellular polysaccharide) = significant affects pulmonary function
139
How easily is this eradicated from the respiratory tract
- Almost impossible to eradicate from the respiratory tract
- Continued impairment of respiratory tract immunity
- Biofilms in the lungs
140
What is the most frequent cause of death in the CF population?
Pseudomonas aeruginosa
