Lecture 32 to 37 Respiratory system Flashcards

Question

Influenza

Answer 1

* orthomyxo virus (-) ss RNA * TBC sialic acid Adults Sx: * rapid: onset after short incubation of 1 to 4 d * sudden: malaise and headachle lasting a few h * abrupt: rise of fever, chills, severe muscle aches. Loss of appetite, non-productive cough lasting 3 to 8 d * recovery: complete in 7 to 10 d * Pt contagious before sx appear (end of 1st d) for next 7 d * risk of secondary infection highest in time from 6 to 12 d after infection Children's Sx: * same as those in adults, PLUS * high fever * G.I. sx: vomiting, ab pain * earache (otitis media) * muscle pain and sometimes swelling * febrile convulsions (rare but occurs in children \< 3 y) Complications * primary viral pneumonias * secondary bacterial pneumonias * muscle inflammation: cardiac involvement * rare neuro syndromes: Guillain-Barre, encephalitis, Reye's syndrome in Children (made worse by aspirin and aspirin containin drugs) Types * Type B: found only in humans; less severe than type A; 2 valences against B (Victoria-like & Yamagata-like) * Type C: cause mild illness in humans & do not cause epidemics, pandemics. * Type A: disease of birds -\> all 15 H and 9 N types Virulence factors: Matrix protein (M1), NA, HA, ion channel M2 protein (type A only), RNA segments (below) * 8 segments: Influenza A & B * 7 segments: Influenza C * M1 & M2 proteins common to all A viruses * - caveat: hidden from immune system Influenza virus increases the susceptibility of the lower respiratory tract to bacterial invasion by destroying cilated cells. Entry of influenza into cell * Stage 1: attachment * Stage 2: Entry & Fusion w endosomal vesicle (not cell membrane) * Stage 3: Uncoating

Answer 2

* Rod-shaped * Hemagglutinin is **Major Ag** against which neutralizing Ab are directed * **highly variable**: responsible for evolution of new strains * **4 HA subtypes** described in humans: HA1-3, HA5 * carried out by **cell proteases** * **Note: **HA spikes extend like a spring bringing viral and cell envelope together * Receptor Mediated Endocytosis (RME) involving sialyloligosaccharide on cell membrane bring Both NA & HA intracell so neutralising Ab cannot reach.

Answer 3

* A type of sialidase enzyme: removes terminal sialic acid residues from glycoproteins and glycolipids * Functions/roles * enables release of newly formed budding virus from host cells * helps virus move thru mucin layer * 2 subtypes: N1 and N2

Answer 4

Etiopath: - aerosol droplets - contacts respiratory epithelium of middle RT. - desquamation of cells - triggers T-cell response - interferon response - leading to 2o endogenous infections from several microbes causing pneumonia

Answer 5

* Shift: A * Drifts: ABC

Answer 6

* Type B is as severe as A but not as common (epi less sevre) * Only A has animal reservoir and cause pandemics * Types A & B can cause epidemics

Answer 7

Prokaryotes * mycoplasma sp. - mycoplasma = walking pneumonia; most common cause of walking pneumonia; kids under 5; crowded institutions - no quick, simple or cheap etiologic lab dx * Chlamydia sp. * Chlamydophilia -\> walking pneumonia * C. psittaci -\> parrot fever causing pneumonia, post-strep rheumatic fever, and giant cell myocarditis * Legionella sp. C. pneumoniae & mycoplasma infections present w same RT sx Eukaryotes * usually fungi; Respiratory fungi in middle US (appalachians) * Histoplasma sp. * Blastomyces sp. * Coccidiodes sp. * Candida sp. Broad-spectrum antibiotics do not treat walking pneumonia effectively

Answer 8

* All strep are aerotolerant anaerobes (facultative) -\> can survive reduced O2 levels -\> deep in RT - part of nl flora - cause of lobar pneumonia * Clinical sx: pneumonia, sinusitis, otitis media * S. pneumoniae on blood agar * Note alpha-hemolysis = strep * p disk=optochin antibiotic inhibits pneumococcus * Epi: commonest cause of community acquired pneumonia * part of nasopharyngeal flora * no animal or env. reservoir -\> humans are the reservoir * Tranmission: * Exogenous: person to person via droplets * Endogenous: if there is predisposing condition such as influenza

Answer 9

* capsule * IgA protease * pneumolysin * autolysin * transformation Prevention: polyvalent capsular polysaccharide vaccine ex. pneumovax, pnu-immune * immunises against 23 of the most common serotypes * indicated for protection of high risk individuals such as young and elderly and those w: chronic disease, HIV, alcoholism * also: 7-valent conjugated vaccine: T-cell dependent response

Answer 10

* inhibits ciliated epithelial cell activity * cytotoxic for alveolar and endothelial cells * causes inflammation * decr. PMN effectiveness

Answer 11

Viral agents * influenza virus * adenovirus * RSV * SARS * Metapneumovirus * Bunyavirus Bacterial agents * strep. pneumonia * mycoplasma pneumonia * Legionella pneuphilia * chlamydia pneumonia * Ricketssia sp. * Coxiella burnetti * Pseudomonas sp. * bacillus anthracis * mycobacterium tb

Answer 12

* Sx: bronchopneumonia, lung abscesses, common in alcoholics and addicts * Enterobacteriaeceae, Gram -ve bacillus, large capsule (mucoid apperance) * part of microbial flora: nl in GIT * 2 high affinity iron uptake systms: aerobactin & enterochelin * necrosis of lung tissue due in part to LPS * can cause severe and destructive nosocomial pneumonia -\> **red currant jelly sputum & putrid odour**

Answer 13

* lung abscesses/aspiration pneumonia * \>1 area of lung parenchyma replaced by cavities filled w debris. * large % of cases are polymicrobial (\>1 species) -\> putrid odour to breath & sputum * range of microrganism in addition K. pneumoniae can include: * S. aureus * anaerobes and microaerophiles from nl mouth flora * microaerophiles on outside use up O2; anerobes grow on inside

Answer 14

* Sx: Legionnaire's disease (pneumonia), pontiac fever (self-limiting) Family: Legionellaceae * single genus: Legionella * Gram -ve rods, motile, non-spore forming * 49 species, 70 serogroups * \>80% of all infections due to L. pneumophilia sergroup 1 * can be associated w epidemics * uptake is via phagocytosis; prevent fusion of phagosome-lysosome. * much of damage = host inflammatory response. * virulence factors * intracell growth * endotoxin * extracell protease * Epi: expsure = inhalation of contaminated aerosols * person to person transmission = rare * can survive ~50C for \> 30 min. * Does not take saffranin couterstain so is invisible under gram stain -\> silver stain * *

Answer 15

* Gram -ve rods, strictly **aerobic,** * highly motile w multiple flagella, versatile metabolism * opportunist ubiqitous in fresh water sources * Catalase + * Oxidase + * encapsulated * thrives in aquatic environment * non-hemolytic; produces very mucoid colonies on conventional agar * some strains produce pigments: **Pyocyanin, pyoverdin/Fluorescein** giving a **green colour** to colourles media; **smells like Grapes!** **Etiopath:** * Toxin inactivates E2-F by ribosylation (same as Diphtheria toxin) **Sx** * only weakly pathogenic to persons w normal innate acquired immunity; most common infection is **Otitis Externa** (Swimmer's ear) * Dangerous for persons w structural defects in body defenses. * burn victims * CF: causing necrotising bronchial pneumonia * pseudomonas aeruginosa & Burkholderia cepacia are now considered CF pathogens * often fatal nosocomial infection * osteomyelitis in diabetics & IV drug users * nosocomial UTI * Eccthyma gangrenosum: black necrotic lesions on skin Rx: * Pipericidin * Fluoroquinolones for UTI * Aminoglycosides

Answer 16

* grow in long parallel chains "cords" * aerobic * non-spore forming * resist drying but still sensitive to heat * unusual cell wall -\> does not take up Gram stain -\> afb stain - killed by gentle heating -\> pasteurization * Cell wall structure: * mycolic acid = straight chain hydrocarbon = wax * Lipoarabinomannan (LAM) = inactivates macrophages and scavenge free radicals * grows slowly in lab: 2 to 8 wk * Etiopath: intracell survival in alveolar macrophages * prevent oxidative burst & inhibit phagosome-lysosome fusion -\> role of sulfolipids * resist lysosomal enzymes, reactive O2 species * escape phagosome * LAM & mycolic acids * secrete siderophores: exochelins Tb & AIDS * resistance to Tb largely dependent on subset of CD4+ helper T cells that produce alpha-interferon * normally: enhance antimicrobial activity of macrophages * in active AIDS, total population of CD4+ helper T cells reduced. Culture & Dx of M. tb * M. Tb is hydrophobic so grows on top of agar instead of inside agar; requirees * Lowenstein-Jensen agar * Oleic acid - albumin broth * Also Z-N & R-A stains

Answer 17

* multiple combination therapy * antimycotic agents include: 1st line: * isoniazid * rifampin * streptomycin * ethambutol 2nd line: * para-aminosalicyclic acid * cycloserine * fluoroquinolones Prevention * prophylactic antimycotics * BCG (Bacillus Calmette-Guerin) vaccine * attenuated M. bovis strain

Answer 18

* MDR-TB: resistant to both isoniazid (INH) and rifampin * XDR-TB: MDR + resistant to any fluoroquinoloine + 1 of 3 following injectable drugs: amikacin, capreomycin, kanamycin * TDR-TB: XDR-TB that is completely resistant to all tested drugs (preliminary definition)

Answer 19

* Teleomorph = recognized sexually reproducing form of fungs * Anamoprhin = asexually reproducing form; usually ill-defined * Ex. Ajellomyces capsulatus & dermatitidis

Answer 20

* 2 presentations: 1. pulmonary & 2. extrapulmonary disseminated * Epi * similar to that of histoplasmosis * found in decaying organic matter * outbreaks associated w contact w soil * most infections: N. America

Answer 21

* most virulent of all human mycotic pathogs; expsoure is through inhalation of arthroconidia (endospores) from soil * Spherule protects spores from phagocytosis (fig. below) * mostly in desert areas of US but not exclusive (SW USA, Arizona, Cali), N. Mexico, S. & Central America * Self-limited flu-like illnesses