Chapter 22 Respiratory Infections

1.    Barrier Protection and Anatomical Review

a.    Anatomy (11,500 liters of air per day filtered)

                                                         i.      Eyes and Nose = portals

                                                        ii.      Lymphoid tissue

                                                       iii.      Mucus Membrane & Cilia

                                                       iv.      Epiglottis to physically separate

  v.      Coughing, spitting, sneeze -

approximately 4,600 droplets

at a muzzle velocity of 152 feet per second

30 minute hang time potentially containing some 35 million viruses

b.    Normal flora (URT)

                                                        i.      Diphtheroids – Corynebacterium sp.

                                                       ii.      Staphylococcus epidermidis

                                                      iii.      Streptococcus sp.

                                                      iv.      Neisseria sp.

                                                       v.      Fungi and viruses

c.    Sterile areas (LRT) – below the epiglottis,

trachea alveoli

Respiratory Infections

Disease	Etiologic Agent	Pathogenesis (mediated by exotoxins and virulence factors)	Symptoms	Transmission	Prevention and Treatment
Bacterial Infections of the Upper Respiratory Tract
Streptococcal Pharyngitis	Streptococus  pyogenes GPCch, catalase-β hemolytic Lysogeny in scarlet fever & possibly necrotizing fasciitis	b hemolysins, M & G proteins interfere with phagocytosis), F(attachment),  DNAase, SPE’s superantigens, streptolysins	Sore throat – fever Other 2° sequela rheumatic fever, glomerulo-nephritis, SPSE	droplet  through air or contact	Penicillin Quick treatment limits sequela Lifelong immunity but many strains
Diptheria	Corynebacterium diphtheriae GPR, pleomorphic, Irregular staining   Disease is caused by lysogenic bacteria	Diphtheria toxin – gene repressed when iron is present – interferes with protein synthesis ADP	Sore throat, fever, fatigue, malaise Pharyngeal membrane, heart and kidney damage, paralysis	Droplet - air  Reservoir = convalescent & asympto-matic people Some fomites	Controlled by vaccine Requires immediate treatment w/antitoxin
Related URT infections of ears - otitis, sinus – sinusitis & eyes - conjunctivitis	Haemophilus influenzae GNR – coccobacilli fastidious Streptococus  pneumoniae GPDC, catalase- α hemolytic	Capsule     Capsule, adhesions,	Earache (perforated eardrum)   Weepy, itchy eyes	Droplet, air & contact Carrier rate >80% Viral infections predispose 2° bacterial	Antibiotics Otitis media = 30 mill Dr. visits Wash hands Minimize touching   HIb vaccines
Disease	Etiologic Agent	Pathogenesis	Symptoms	Transmission	Prevention and Treatment
Viral diseases of the URT
Colds	1.       Rhinoviruses –picornaviridae >100 serotypes 2.       Coronaviruses 3.       Adenoviruses >45 types	Attachment via receptors to resp. mucosa   Damage from inflammation	Runny nose, mild sore throat, cough, malaise, occasional fever	Droplet, contact & air All can lead to 2°infections	Adenovirus infections are harsher – fever bed ridden Control from interferon

Disease	Etiologic Agent	Pathogenesis (mediated by exotoxins and virulence factors)	Symptoms	Transmission	Prevention and Treatment
Bacterial Infections of the Lower Respiratory Tract
Typical Pneumonia	Streptococus pneumoniae GPDC, catalase- α hemolytic, sensitive to Optochin - Taxo P disc	Capsule,   α hemolytic, pneumolysins, sputum invasive Septicemia & meningitis	May begin URT, then fever, productive cough, hemoptysis, pleurisy-pain on breathing	droplet  through air or contact	Penicillin Quick treatment Vaccine Lifelong immunity but many strains >80
Nosocomial Pneumonia	Enterobacteriaceae GNR Klebsiella pneumoniae, Serratia sp, E. coli	Capsule, requires an immuno-suppressed status	Like above hard to distinquish	Droplet - air Endogenous	Control exposure, do culture and sensitivity requires specific therapy
Walking Pneumonia	Mycoplasma pneumoniae No Gram Stain, no routine culturing	Attach to respiratory mucosa, destroy cells & cilia	Fever, headache, myalgia, and fatigue	Travel in smallest droplets through air or contact	Erythromycin or tetracycline families
Whooping Cough	Bordetella pertusis Small GNR – bipolar staining Strict aerobe, not on routine culture	Attachment proteins, inhibits cilia, tracheal cytotoxin = Nitrous oxide	Cold-like, paroxysmal coughing – making distinctive whoop	Droplet – air (can’t survive outside long)	Vaccine Erythromycin Reservoir are mild infections in adults & older children
Tuberculosis	Mycobacterium tuberculosis, Mycobacterium bovis, Mycobacterium avium, Mycobacterium sp. Aerobic AFB	Intracellular in macrophages, granuloma = tubercle	Chronic – slight fever, consumption, night sweats, cough (hemoptysis)	Droplet – air, coughing, spitting (survive outside a longtime)	Multi-drug therapy INH, Rifampin, Streptomycin, Skin test MDRTb BCG Most common amongst HIV, elderly, ethnic groups
Disease	Etiologic Agent	Pathogenesis	Symptoms	Transmission	Prevention and Treatment
Viral diseases of the LRT
Influenza	Orthomyxoviruses 8 RNA segments	H and N antigens that change	Headache, fever, myalgia, fatigue	Droplet, contact & air Can lead to 2°infections	Vaccines – multivalent Reyes syndrome
RSV	Respiratory Syncytial Virus	Fuses or clumps epithelial cells into syncytia	Cold-like, croup cough	Droplet, contact & air 2°infections	Very serious for infants Isolation, ribavirin synagis - bioengineered monoclonal abs http://www.pharmaceuticalonline.com/article.mvc/Synagis-humanized-monoclonal-antibody-protect-0001
Hantavirus http://www.cdc.gov/ ncidod/diseases/ hanta/hps/noframes/ prevent3.htm	Hantavirus – bunyavirus family	Virus invades mucosal epithelium, inflammatory reaction results in bleeding into lungs	Fever, myalgia, nausea, vomiting, diarrhea, cough, shortness of breath, possible death	Aerosols from rodent urine & feces	No person to person transmission, control exposure to rodent droppings, etc.
SARS Severe acute respiratory syndrome	Coronavirus SARS Co-V	Virus induced or immune mediated??	high fever [>38.0°C or 100.4°F], headache, myaligia, diarrhea, dry cough,  pneumonia	Droplet, contact & air	Isolation
Disease	Etiologic Agent	Pathogenesis	Symptoms	Transmission	Prevention and Treatment
Fungal diseases of the LRT
Valley Fever	Coccidioides immitis	Arthrospore -> spherules Invasive	Mild, chronic, immune response initiated – rash, fever, headache	Not communicable	Fluconazole Endemic Avoid dust Skin tests
Histoplasmosis	Histoplasma capsulatum	Enters macrophages forms granulomas	Fever, cough, chest pain	Immune suppressed particularly HIV	Fluconazole Endemic Bat and bird droppings Avoid caves Skin tests
Parasitic diseases of the LRT
Lung fluke http://www.k-state.edu/parasitology/ 625tutorials/FIGkellicott02.jpg	Paragonimus westermanii	Large worm 10mm – in lungs, disables but mot fatal	coughing	worms produce eggs coughed up & spit out or swallowed passed in feces-> first intermediate host is a snail.  2nd host crab human eat undercooked crab or crayfish	Wash hands, don’t eat raw seafood

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