Airborne Bacterial Diseases

Upper Respiratory Tract (URT)

  1. Streptococcal Pyogenes

  • Streptococcal Pharyngitis:

    • sx: red sore throat w/ white patches

    • can develop into Scarlet Fever: strep throat w/ skin rash (capillary damage)

    • rheumatic fever: antibodies against M-protein attack connective tissue and potentially myofiber

    • Acute glomerulonephritis: rare immune response to M-protein

    • complications:

      1. Erysipelas: deep red inflammation

      2. puerperal sepsis: infected uterus, “childbed fever” 1-10 days postpartum

    • Necrotizing Fasciitis: flesh-eating bacteria

  1. Corynebacterium diphtheria

  • diphtheria: localized infection of the throat

  • produces exotoxin inhibiting protein synthesis

  • results in accumulation of pseudomembrane on tonsils/pharynx

    • Toxins can circulate:

      • Bull neck, heart damage, and nerve damage

  • Vaccine: DTaP (or DTPa/TDaP) protects against diphtheria, tetanus, and pertussis

  • Tx: abx, and antitoxin

  1. Neisseria meningitidis

  • meningococcemia (sepsis) and meningococcal meningitis

  • rapid onset (as soon as 2 hrs)

  • sx: bright red patches and blue/black spots

  • dx: spinal tap

  • complications:

    • Waterhouse-Friderichsen Syndrome: lesions in adrenal glands

  1. Haemophilus influenza type B (HIB)

  • Vaccine: HiB or DTaP+HiB vaccine

Lower Respiratory Tract (LRT)

  1. Bordetella pertussis

  • Pertussis “Whooping Cough”

  • effects: paralyzes cilia

  • Vaccine: DTaP/TDaP

  • Sx: multiple paroxysms of coughs, followed by “whoop” sounding inhalation

    • Catarrhal stage: 1-2 wks

    • Paroxysmal stage: 1-6 wks (can be up to 10 wks)

Mycobacterium tuberculosis

  • 2 billion people infected globally

  • 90% of people carrying latent TB will never develop an active infection

  • TB Complex:

    1. M. tuberculosis

    2. M. africanum

    3. M. bovis

  • contain Mycolic acid in the cell wall

  • sx: cough, fever, night sweats greater than 3 wks

    • weight loss

    • breathing pain

    • hemoptysis (blood-stained sputa)

  • following inhalation of aerosol bacilli, bacteria invade alveoli, where cells are taken up by macrophages

  • granuloma: cell infiltrate serving as a survival niche where bacteria can disseminate

  • Ghon’s complex: lesion in the lung caused by TB, calcified focus

  • Tubercules (hard nodules) or caseous masses (lrg cheeselike mass) break down respiratory tissues, forming cavities in the lungs

  • Miliary tuberculosis: form of TB w/ wide dissemination (hematogenous spread) in body

  • discharge of caseating tubercle from veins into bronchi can be swallowed, causing TB in the GI tract

  • Dx: Quantiferon Gold (latent TB infections)

  • can be multidrug-resistant TB (MDR-TB)

  • Tx: PRIEST

    1. Pyrazinamide

    2. Rifampin

    3. Isoniazid

    4. Ethambutol

    5. STreptomycin

  • Vaccine: Bacillus of Calmette and Guerin (BCG)

    • only 60-80% effective

    • not given in the US

    • can complicate ppd skin test

Mycobacterium avium complex (MAC)

  • isolate in more than 95% of AIDS pts

  • highly resistant to abx

  • Mortality rate: 70-90% w/i 4 months

Mycobacterium marinum

  • opportunistic infections in humans

  • causes aquarium granuloma

Healthcare-acquired pneumonia (HAP pneumonia)

  1. Staphylococcus Aureus

    • Methicillin-resistant Staphylococcus Aureus (MRSA)

    • can cause necrotizing pneumonia

  2. Pseudomonas aeruginosa

    • mucus-looking

Community-Acquired Pneumonia (CAP)

  1. Streptococcus pneumonia

    • pneumococcal pneumonia

    • causes 80% of bacterial pneumonia

    • sx: rust-colored sputum

    • types of pneumonia:

      • lobar: entire lobe

      • double: bil lungs

      • bronchopneumonia: respiratory passageways

  2. Mycoplasma pneumonia

    • “walking pneumonia”

    • no cell wall

    • dx: Cold Agglutination screening test (CAST)

    • tx: abx (not B-lactams)

  3. Legionella pneumophila

    • Legionnaire’s disease

    • Pontiac fever: a milder form of pneumonia

    • relation to water collection systems

  4. Coxiella burnetti

    • Q Fever: results from breathing airborne particles

    • “walking pneumonia”

    • obligate intracellular parasite

    • prevalent in livestock

  5. Chlamydophilia psittaci

    • “walking pneumonia”

    • from infected psittacine birds

  6. Chlamydophilia pneumoniae