Respiratory Infectious Diseases
Streptococcus pneumoniae- (G+ cocci)
Normal flora of nasopharynx
Disease: pneumococcal pneumonia- typical wet pneumonia
Large capsule layer produced as virulence factor (avoid phagocytosis)
Transmission: Opportunistic when large quantity is inhaled into lungs, inflammatory
response causes fluid build-up
Treatment and prevention: typical antibiotics, vaccine
Mycoplasma pneumoniae- (bacteria without cell wall)
Pleomorphic, fragile bacteria
Disease: primary atypical (walking) pneumonia
Fever, fatigue, dry and unproductive cough
Transmission: respiratory droplets person to person
Treatment: typical antibiotics (but not those that inhibit cell wall synthesis)
Mycobacterium tuberculosis- (AF+, waxy bacillus)
Kills 2-3 million people annually worldwide
Disease: Tuberculosis (TB)
90%- mild fever, flu-like (bacteria become captured by macrophages in lungs, but
not digested)
10%- severe cough, chest pain, high fever, bloody sputum due to
ruptured/perforated lungs
(can spread from lungs to other organs like kidneys, liver, bone, etc.)
Transmission- direct respiratory droplets and infected sputum
Streptococcus agalactiae- (known as Group B Strep)
Disease: most prevalent cause of neonatal pneumonia and neonatal meningitis in U.S.
Transmission: normal flora of vagina, pharynx, large intestine
Pregnant women screened for vaginal colonization in 3rd trimester
Treatment: antibiotics and immunotherapy
Streptococcus pyogenes- (Group A Strep)
Normal flora of throat, nasopharynx, sometimes skin
Virulence: release of toxins, harmful enzymes, damage from strong immune response
Transmission: 5-15% population carriers…direct respiratory droplets, food
Disease: pharyngitis and tonsillitis (strep throat)- red, enlarged, tender throat, fever,
headache, nausea, white pus nodules
strep throat can lead to:
Scarlet fever- red rash of skin
Rheumatic fever- delayed inflammation of joints, subQ tissue, heart causing
endocarditis and heart valve damage
____________________________________________________________Also causes: Skin infectionsPyoderma: burning, itchy lesions…contagious yellow crusty skin
Erysipelas: red, swollen skin with elevated edges
Cellulitis: diffuse, spreading, deep skin infection of subcutaneous, reddened and painful
____________________________________________________________
Bordetella pertussis- (small G- bacilli)
Disease: pertussis (whooping cough)
7-10 day incubation, 1-2 weeks non-specific resp symptoms, 2-4 week whooping
cough
Caused by- attachment to cilia of upper resp tract, produce 5 toxins which
increase mucus secretions, inhibit phagocytosis, paralyze cilia
Transmission: respiratory droplets, human only known reservoir
Treatment and prevention: macrolides (reduce duration, do not eliminate symptoms),
vaccine
Mumps Virus- (a Paramyxovirus)
Disease: mumps (12-25 day onset)- infected salivary glands, swollen cheeks, fever,
muscle aches, malaise
Complications can be encephalitis, meningitis, swelling of testes or overies,
permanent deafness, spontaneous abortion
Transmission: (Human only host) saliva and resp droplet direct or by fomite into lungs
Prevention: vaccine (in MMR vaccine)
Influenza virus- (enveloped RNA)
Rapidly mutated virus, many known strains
Disease: Flu- rapid onset of fever, fatigue, headache, muscle pain
(often complicated by secondary infection)
Transmission: respiratory droplets into lungs (humans, pigs, avian all known reservoirs)
Treatment and Prevention: Tamaflu™ and vaccine available
Respiratory Syncytial Virus- (enveloped RNA)
Disease: RSV (viral pneumonia)
Most common lower resp infection in children under 2
Causes respiratory cells to fuse (syncytium formation) and lose function
Flu-like symptoms in adults
Transmission: resp droplets
Rhinovirus, Echovirus, Coronavirus, etc. (a big group of naked RNA viruses)
Disease: Common Cold- runny nose, cough, mild fever
Transmission: resp droplets