Respiratory Infections Flashcards
Location of Respiratory Infections
Trachea, Bronchi, Bronchioles, Alveoli
Barriers to infection
Nasal hair, Mucosillary cells, Coughing, Normal flora, Phagocytic inflammatory cells
Normal flora
- changes with time (due to hospitalization)
- alpha hemolytic colonies in pharyngeal culture
Pathogens
- alpha hemolytic colonies in sputum or bronchial aspirate
Differentiating infection
- look at method and site of infection
- presence of white blood cells
- number of organisms present
- clinical syndrome present
- some pathogens are always present (M.TB)
Respiratory Infections (Risk Factors)
- Imunnologic status
- Age (elderly, young at higher risk)
- Reduced clearance promotes infection
- Airway obstruction (H. flu epiglottitis)
- Seasonal patterns contribute (M. pneumo has none)
Empirical treatment
- antibiotics should be given before ID for ICPs
- infections with hard-to-reach specimens
- infections with known/recurring pathogens
Virulence factors
- adherence, fimbrae (Enterics, Streps)
- toxin elaboration (C. diphtheriae, Pseudomonas, pertussis)
Evasion of host defense
- capsules for preventing phagocytosis (S. pneumo, H. flu, Pseudomonas, Klebsiella)
- intracellular (TB, Chlamydia)
- Proteases (cleave antibodies)
Upper Respiratory Tract Infections
Pharyngitis, Sinusitis, Otitis media, Epiglottitis, Pertussis
Pharyngitis
- commonly Group A strep in kids or viral (with rhinorrhea)
- symptoms of Group A strep
- culture or rapid antigen testing
- person-to-person transmission
- pain, difficulty swallowing, fever with bacterial
- C. diphtheriae: pharyngeal membrane
URT Infections (pathogenesis)
inflammatory effects of bacteria
URT complications
sinusitis, otitis media, pneumonia
URT lab diagnosis
- primary: differentiate between viral and bacterial
- secondary: detect uncommon bacterial causes
URT culture
- streak SBA
- Latex agglutination
- Rapid antigen test
- treat with penicillins and cephalosporins
Sinusitis (causes)
- commonly viruses (rhinovirus, influenza)
- 2% are bacteria (S. pneumo, H. flu, S. pyogenes, M. catarrhalis, S. aureus)
- fungal is uncommon
Sinusitis (pathogenesis)
- swelling and blockage of sinuses
- pain and possible complications
- complications: orbital cellulitis, osteomyelitis, meningitis
Sinusitits (lab diagnosis)
- direct sinus puncture or aspiration
- culture on SBA, MAC, Chocolate
- empirical information
Otitis media
- most common in preschool aged kids
- fever, irritability, ear pain, drainage, red tympanic membrane
Otitis media (pathogenesis)
- due to anatomic immaturity
- causes damage to tympanic membrane
Otitis media (lab diagnosis)
- empirical
- antibiotic treatment in kids < 2 y/o
Epiglottitis
- caused by Hib
- preschool-aged kids
Epiglottitis (pathogenesis)
- severe pharyngitis, sore throat, severe pain on swallowing
- edema in soft tissues
- sudden onset of airway obstruction
- requires hospitalization and IV fluids
Epiglottits (lab diagnosis)
- direct swab culture and blood cultures
- direct smear (WBC’s, pleomorphic GNR’s = H. flu)
- culture on chocolate
Pertussis
- caused by Bordetella
- highly transmissible in ICPs, babies
- vaccine available
Pertussis (pathogenesis)
pertussis toxin
Pertussis (lab diagnosis)
- nasopharyngeal swab using Dacron/Calcium alginate
- plate on Bordet-Gengou
- serology: DFA testing, PCR testing
Lower Respiratory Tract Infections
- Bronchitis, Bronchiolitis, Influenza, SARS, Pneumonia, Empyema, TB
- caused by inhalation of aerosols, aspiration of oral/gastric contents, or hematogenous spread
Bronchitis and Bronchiolitis
- follows epidemics of influenza, RSV, and other viruses
- more frequent in winter months
Bronchitis and Bronchiolitis (pathogenesis)
- infection and damage to the airway
- inflammatory response, necrotic debris, edema
- begins as URT infection
- acute is infectious form
- chronic requires 3 months of symptoms for 2 years
Bronchitis and Bronchiolitis (lab diagnosis)
- similar procedure as pharyngitis
- secondary infection easily obtained from sputum
- hospitalized patients tested for RSV for infection control
Influenza
- late fall, early winter
- Influenza A and B
Influenza (pathogenesis)
- antigenic shift (production of new virus)
- fever, myalgia, fatigue
Influenza (diagnosis)
- detection of virus, viral antigen, or viral nucleic acid
- treat with neuraminidase inhibitors or vaccine
Severe Acute Respiratory Syndrome (SARS)
- fever without cough
- dyspnea
- progressive respiratory failure
LRT (Viral causes)
Adenovirus, Metapneumovirus, Bocavirus
Community-acquired pneumonia
- most affected are elderly or have underlying disease
- kids/elderly: RSV, parainfluenza
- adults: S. pneumo, Hib, M. pneumo
- atypical: M. pneumo, Legionella pneumophila
C-A pneumonia (pathogenesis)
- fever, lung infiltrates
- cough with blood-tinged sputum, left shift WBC count
C-A pneumonia (lab diagnosis)
- therapy is empirical
- blood cultures and sputum on hospitalized patients
- PCR and other molecular tests
- antigen tests
- direct examination of sputum
Direct examination of sputum
Acceptable: < 10 epithelial cells, > 25 PMN’s
Expectorated sputum
- no WBCs
- heavy epithelial and bacteria
- saliva, not sputum
Aspirated sputum
- no WBCs or organisms
- specialized cells from bronchial tree and mucus
Health Care-Associated Pneumonia (HCAP)
- hospitalized or in a nursing home facility
- can also be ventilator associated pneumonia (VAP)
- greater risk of multi-drug resistant pathogens
- Pseudomonas, Kleb. pneumo, Acinetobacter, MRSA
HCAP (pathogenesis)
- patients own respiratory flora, GI tract or hospital flora
- due to aspiration of flora
- intubation of lower airway pushes flora deeper
- nasogastric intubation
- fever, altered WBC count, purulent sputum
HCAP (lab diagnosis)
- same as community-associated
- expectorated sputum specimen
- SBA, Chocolate and MAC
- anaerobic cultures if no contamination
Empyema
- collection of purulent fluid in pleural cavity
- S. aureus, S. pneumo, S. pyogenes
Empyema (pathogenesis)
- fever, chills, night sweats
- complicates chest surgery
- limits motion and function of lungs
- resistant to antimicrobials
Empyema (lab diagnosis)
aspirate of pleural fluid (thoracentesis)
Tuberculosis
- Mycobacteria in ICP’s
- NTM’s (Mac, M. kansasii, M. chelonae)
- Opportunistic fungal pathogens
Tuberculosis (lab diagnosis)
- acid-fast stain
- skin test
- serology, nucleic acid tests
Aspiration pneumonia
- gastric or oropharyngeal are inhaled into LRT
- C-A: S. pneumo, H. flu, Staph, Enterics
- HACP: Gram-negatives like Pseudomonas
- use broad spectrum antibiotics
Respiratory Infections in ICPs
- Pneumocystis
- Bacterial pneumonia and tuberculosis
- Cryptococcus
- Lab: sputum and blood culture, acid-fast, fungal tests
Bioterrorism respiratory infections
B. anthracis (anthrax attack in 2001)
