Pneumonia Flashcards
Pneumonitis
Causes
Inflammation of parenchyma (alveoli)
Caused by viruses, bacteria, radiation therapy, sepsis, adverse drug rxns, hypersensitivity rxns, smoking, and chemicals.
Pneumonia
Inflammation w/ fluid buildup in alveoli that may cause decreased gas exchange
Pathogenesis of pneumonia
Colonization of upper respiratory tract w/ injury to mucociliary escalator (such as smoking or virus).
May aspirate oral flora / vomit.
Sometimes organisms are directly inhaled (TB). Hematologic seeding by septic emboli from endocarditis may occur as well, mainly in lower lobes due to higher perfusion.
Clinical signs of pneumonia
Fever, chills, dyspnea, cough (dry or productive), pleuritic chest pain, anorexeia, headache, systemic sxs (weight loss / night sweats suggest TB or fungal cause). Hemoptysis is rare (more common w/ bronchitis).
Physical exam (4 things) What is needed for diagnosis?
Need CXR for diagnosis
•Ronchi / wet rales (alveoli “popping” open)
•Egophony and fremitus (vibratory tremors that can be felt through the chest by palpation) both suggest consolidation
•Dullness to percussion suggests a pleural effusion
•Auscultation may be unremarkable if area of consolidation is not close to chest wall.
Radiography ( 3 types of findings)
- Lobar – typically bacterial.
- Interstitial pneumonia / pneumonitis – viral, Pneumocystitis jiroveci, or atypical bacteria. Diffuse.
- Nodules / cavities – mycobacterial / fungal cause
Labs (5 things)
- Sputum or BAL gram stain – must not contain lots of spit due to oral microbiota. Compare ratio of neutrophils to squamous epithelial cells
- Blood cultures
- Urinary antigen testing for Strep pneumoniae or Legionella pneumophila
- Pleural fluid analysis / culture
* Empyema = bacterial infection w/in pleural space. Must be drained immediately to prevent scar tissue from building up overnight, restricting the lungs.
Community Acquired Pneumonia (CAP) Organisms When is it most common? Tx What vaccines are available and for who?
- Caused by S pneumoniae, H influenzae, Legionella pneumophila, M pneumoniae, Chlamydophila pneumoniae, or viruses.
- More common in winter
- Tx – doxycycline, macrolide, or FQ.
- Vaccines are available for Strep pneumoniae and Haemophilus influenza. Useful in children, adults, and elderly.
Hospital Acquired Pneumonia (HAP)
Onset
Tx
Occurs 48+ hrs after intubation
Tx - FQ or beta lactam + macrolide.
Healthcare Associated Pneuonia (HCAP)
Prior hospitalization w/in last 90 days, live in nursing home, or IV antibiotics w/in last 30 days
What type of pneumonia affects the small airways?
Bronchiolitis obliterans organizing pneumonia / cryptogenic organizing pneumonia
Eosinophilic pneumonia caused by?
Parasites or autoimmune disorders
Necrotizing pneumonia caused by?
Oral anaerobes or chemical burn (gastric aspiration).
What is the difference b/w typical / atypical pneumonia?
What organisms cause typical?
What organisms cause atypical?
Typical pneumonia shows organisms w/ gram stain.
Atypical pneumonia shows neutrophils w/ gram stain but no organisms.
2 main typical strains are Strep pneumoniae and Haemophilus influenze.
3 main atypical strains are Chlamydophila pneumoniae, Mycoplasma pneumoniae, and Legionella pneumophila
General characteristics of Chlamydia / Chlamydophila
Type of bacteria
What are inclusions?
Cell wall characteristics
Obligatory intracellular Gram Neg Forms inclusions (phagosomes full of EBs and RBs) Rigid, but lack peptidoglycan
Elementary Body vs Reticulate Body Size Infectious? Replicating? Released?
EB small / dense. RB large / loose.
EB infectious, RB not.
EB non-replicating, RB does binary fission.
EB is released when cell ruptures. RB only found inside cells.
5 steps of Chlamydia life cycle
- Small EB is passively engulfed by host cell and prevents fusion of lysozomes w/ phagosomes.
- EB reorganizes itself into RB, which is metabolically active and starts to divide.
- RB uses host’s ATP. Energy parasite. Replicates.
- When many RB’s are present, they condense into large infectious EB’s.
- Inclusion bursts after 2-3 days and cell dies.
Chlamydia trachomatis causes which 5 disorders?
STD causes urethritis, mucopurulent cervicitis, and PID.
Eye infections cause trachoma and opthalmia neonatorum (acute conjunctivitis in newborns)
Chlamydophila pneumonia Diseases (5 things) Transmission Pneumonia sxs Diagnosis Tx (mild vs severe)
Causes CAP, bronchitis, sinusitis, AOM, and atherosclerosis.
•Transmitted person-to-person via respiratory droplets.
•Pneumonia sxs include sore throat, dry cough, low fevers.
•Diagnose w/ 4x increase in Ab titer
•Tx for mild cases of CAP includes doxycyline or a macrolide. Quinolone used for severe infections.
Chlamydia psittaci Cause Transmission Sxs Diagnosis Tx
Caused by parrots
•Transmitted by inhaling EB from infected bird or bird feces. Rarely transmitted person-to-person.
•Sxs include fever, chills, headache, and dry cough. “Parrot fever”. Often asymptomatic.
•Diagnosed w/ 4x increase in Ab titer
•Tx w/ tetracycline, macrolide, or FQ
Long term complications of Chlamydia infections (4 things)
- Trachoma → blindness
- PID → infertility, pain, ectopic pregnancy
- Urethritis → reactive arthritis
- Cervicitis → C trachomatis may cause cervical cancer
General properties of Mycoplasma species Genome Cell wall Agar Broth Action against host cell Adhesion Tx Vaccine?
Smallest known genome
Lack peptidoglyan –> squishy
Grown on PPLO agar
May form filamentous structures in broth (“myco”, like fungi)
Inhibits host cells catalase –> increased peroxide / superoxide –> host cell damage
Adhere to epithelium via P1 adhesins –> stops ciliary motion –> dry cough
Tx - doxycyclin, macrolide, or FQ
No vaccine
Mycoplasma pneumoniae AKA Transmission Sxs Diagnosis
AKA “walking pneumonia”. Type of CAP.
•Transmitted person-to-person via respiratory droplets. High attack rate in families (contagious).
•Sxs are usually mild w/ dry cough
Diagnosis is rarely confirmed. Best w/ combination of specific IgM and cold agglutinins (Abs directed against blood group I that show up before specific Abs).
Mycoplasma hominis
Appearance
Diseases
Fried-egg appearance
Causes tubo-ovarian abscess, salpingitis, and PID
Mycoplasma genitalium causes?
Causes urethritis and PID
General characteristics of Legionella species Morphology and Gram stain Agar Environment Transmission Peak time of year
•Slender, motile aerobic rods. Gram Neg but take up stain poorly
•No capsule
•Do not form spores
•Grown on buffered charcoal yeast extract (BCYE) w/ increased CO2.
•Found in fresh water and moist soil. Can withstand heat / chlorination so often found in water systems, air conditioning towars, hot tubs, or shower heads. May cause nosocomial infections.
•Transmitted via inhalation of droplets, such as while taking a shower. No person-to-person transmission.
•Infections peak in summer / fall.
Severity increases in elderly.
Most important strain of Legionella
Legionella pneumophila serogroup 1. Causes 80% of Legionella infections.
Legionella’s effect against host cells
Ingested by macrophages by binding to complement receptor. Engulfed by phagosomes, but fusion w/ lysosomes is inhibited. Proliferation → host cell rupture / spread → lung inflammation / tissue destruction
Sxs of legionella pneumonia
Headache, fever, malaise, muscle aches, dyspnea, non-productive cough, abdominal pain, diarrhea, and confusion
Diagnosis of Legionella
ELISA test for urine Legionella antigen (most common method, but only detects serogroup 1).
Sputum DFA stain may also be used
Tx or Legionella
Macrolides, tetracyclines, or FQ
Pontiac Fever
Cause
Sxs
Tx
Influenza-like illness caused by hypersensitiviy rxn to Legionella proteins.
Sxs include fever, myalgia, arthraglia, and headache. NO respiratory sxs. High attack rate (very contagious).
No tx needed, resolves in 2-5 days.
Prevention of Legionella infection
Find / treat environmental water sources w/ superheating or copper-silver ionization.
