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Micro-RespInfxon
Micro- Respiratory infxon
| Question | Answer |
|---|---|
| What are the risk factor for sinusitis? | URI viral infxon, dental infxon, mutations of CFTR gene, smoking in the household, nasal polyps, structural problems (Deviated septum, etc) |
| What is thought to be the mechanism of otitis media infection | a viral infection in the middle ear preceeding a bacterial infxon. |
| What are the risk factor for otitis media? | young age, viral URI, low angle of eustachian tubes, daycare, bottle feeding, smoking in household, prematurity, GERD, cleft palate. |
| when a pt comes in with otitis media due to effusion (not a bacterial infxon) what is the recommended tx? | rx antibiotic but tell parent not to fill it unless symptoms persist for another 48 hours. (wait to see if effusion progresses to a bacterial infection.) |
| What are the PE findings of sinusitis? | pain exacerbated when pt leans forwards, opacification of sinus on transillumination, |
| What are the PE findings of otitis media | gentle pulling on pinna elicits pain, otoscopy to visualize bulging ear drum, pneumatic otoscopy for pressure, pinna red and tender, rx is usually empiric |
| What is the expected outcome of a perforated eardrum? | most perforations re-epithliize and repair themselves. |
| Rx for sinusitis / otitis media ? | augmentin (for moraxella), Amox or TMS empirically (rx and tell pt to not fill unless symptoms don't go away in 2 days). 1.5% of cases are resistnat strep pneumonia serotype 19a, which require levofloxacin |
| What agents most commonly cause otitis media and sinusitis? | Strep. Pneumoniae, H. influenzae, moraxella catarrhalis, fungi (SINUSITIS) (Aspergillus especially) |
| What is the most common fungal agent of sinusitis? | aspergillus |
| Describe the key identifying features of strep pneumoniae | Gram positive, encapsulated lancet shaped diplococci, *atalase negative* , *alpha hemolysis (dark green in color)*, **optochin sensitive** |
| What feature is key to the pathogenesis of strep pneumoniae? | encapsulation. Smooth (encapsulated) strep is pathogenic, rough is not. |
| What virulence factor of strep activates compliment? | pneumolysin. |
| What viruelnce factor of strep prevents phagocyosis? | polysaccharide capsule |
| What virulence factor of strep binds to PAF receptor on epithelial cells ? | phosphorylcholine |
| What are the key identifying features of Haemophilus influenza? | small, non-motile, gram (-) **REQUIRES X (HEMIN) AND V (nicotinamide) FACTORS FOR GROWTH** coccobaccili/pleomorphic baccili |
| H. influenza is in the normal flora of: ? | uppe resp. |
| What is the potentially fatal strain of H. flu ? | tHype b stain "Hib" (5% of isolates) |
| How is H flu idenitified in lab ? | growth on chocolate agar (supplies the required X and V factors (hemin and nicotinamide respectively) |
| What virelence factors are produced by h. flu? | Endotoxin and igA protease (strep also produces IgA protease) |
| What does the PRP vaccine protect against? | H. influenzae |
| Vaccine for H. Influenzae? | PRP vaccine |
| Key features of Moraxella catarrhalis ? | Gram (-) diplococci, aerobic, oxidase + (like neisseria and pseudomonas) in normal flora of URT in almost all children and some adults |
| What disease is a Moraxella infection most likely to cause in a pt with COPD? | bronchitis or pneumonia. |
| Moraxella infection is involved most commonly in what conditions ? | sinusitis, otitis media, and pharnygitis in children |
| Most common bacterial agent of otitis externa? | pseudomonas (can also becaused by staph, less commonly, a fungal (aspergillus) infection (~10%) |
| Rx for otitis externa? | Clean out canal, acidifying solutions (boric acid or acetic acid), topical rx containing neomycin, hydrocortisone, and polymyxin B, topical oloflaxin otic if TM is perf'd. |
| Malignant otitis externa is most commonly seen in what pts? | diabetics and IC'd pts. |
| Most common bacterial cause of malignant otitis externa? | pseudomonas |
| What is malignant otitis externa? | Infection of deeper tissues, cartilage, and bone. Presents with perulent discharge, edema/erythema of pinna, and necrosis. 50% mortality due to cellulitis and osteomyelitis if untreated |
| What is the most common cause of pharyngitis? | viral |
| What is the standard for determination of the etiology of pharyngitis? | culture. Clinical dx based on observation alone is only correct ~70% of the time. |
| Common bacterial agents of pharyngitis (4) | Streptococcus pyogenes, H. influenzae, corynebacterium diphtheriae, bordtella pertussis |
| What is the bacterial agent of strep throat | Strep pyogenes (Group A) Beta hemolytic streptococci. |
| What kind of hemolysis is observed in strep pyogenes? | Beta hemolysis |
| Small pinpoint colonies when grown on blood agar... what bacteria ? | Strep pyogenes |
| A positive PYR test is characteristic of what bacteria ? | strep pyogenes |
| What is the most common cause of bacterial tonsilopharyngitis? | strep pyogenes (but 70% are viral) |
| Pt presents with strep throat + erythemetous rash and red tongue... dx? | scarlitina (scarlet fever) |
| What is erysipelas? | Acute skin infection on face. Often caused by strep pyogenes (group A streP) |
| What are the virulence factors of strep pyogenes? | Capsule (hyaluronic acid), M protein, hemolysins (streptolysin O --> hemolyzes erythrocytes) (streptolysin S -> damages membranes of neutrophils, PLTs, etc) |
| What is that function of streptolysin O and streptolysin S? | Streptolysin S hemalyzes erythrOcytes, while Streptolysin S damages membranes of neutrophils and pLTs, etc |
| What is the mechanism of rheumatic heart disease? | antibodies against group A carbohydrates cross react with heart valves and sarcolemmal membranes (acute rheumatic fever) |
| What is the cause of the strawberry tongue seen in rheumatic heart disease? | Due to an erythrogenic toxin produced by the bacterial strains |
| Titer for what serum antibody is useful in dx of rheumatic heart disease? | serum streptolysin O antibody. (b/c pt maay not recall having sore throat) |
| Rx for group A strep? | Penillin G or erythromycin if they have a penicillin allergy |
| Rx for prophylaxis of recurrences ARF | penicillin |
| What is the cause of the tissue damage seen in erysipelas? | invasion of the bacteria into the tissue. It can be thought of as a superficial cellulitis |
| What are the common bacterial agents of cellulitis (2) | Group A strep and staph aureus. Most commonly due to wounds, cuts, bites, or burns |
| What is an aschoff body? what disease is this seen in ? | A nidus of macrophages with adjoining lymphocytes and fibrosis. Seen in rheumatic carditis. |
| In an H&E stain, red cells suggest.... | Red cells are dead or dying "red is dead" |
| What are the two major type of H. flu. | Capsulated type B serotype: most deadly form. Potentially life threatening meningitis and epiglotittis. 2) non-encapsulated (not-typable strains): cause local infections of sites contigious with URT (pharyngitis, otitis media) |
| PRP capsule is a characteristic virulence factor of what bacteria? | H. influenzae (PRP is all the target of the vaccine) |
| What ist he most common cause of childhood meningitis? | Used to be H. flu, but since advent of vaccine, pneumococcile and meningococcal meningitis are now most common |
| Growth on chocolate agar is characteristic of what bacteria? | H.flu |
| Tx of H. flu infxon? | 3rd gen cephalosporine (ceftriaxone or cefotaxime. Strain can be ampicillin resistant with OR WITHOUT B-lactamase |
| When can the PRP vaccine be given ? How does the body resist infection prior to this ? | 2 months of age. Acquired maternal immunity is present for the first 2 months. |
| Describe the key feature of corynebacterium diptheriae | gram +, catalase +, aerobic (or fac. anaerob), non spore forming rod. |
| Culture that only grows on medium containing POTASSIUM TELURITE... what bacteria? | Corynebacterium diptheriae. |
| What is the diagnostic feature (microbiologic lab finding) of diptheriae ? | It will only grow in the presence of telurite |
| "Bloody tears" is a finding of what disease ? | diphtheriae (due to ruptured membrane of conjunctive) |
| Mechanism of diptheriase toxin? | Lysogenic bacteriophage encoding tox+ gene, creating a diphtheriae causing strain. A fragment = active. B fragment = binding. A fragment enters cytosol and inactivated EF2 (MRNA and TRNA can no longer interact) |
| What disease feature the formation of a pseudomembrane in the throat. How is this formed. | Diphtheria. **This pseudomembrane forms as a result of dead epithelial and inflammatory cells plus fibrin rich exudate coalescing** |
| What is the tx for diphtheria ? | Antitoxin is the only specific treatment. Penicillin is sometime given as an adjunct tx because bacteria is not invading anything, so it is difficult to get penicillin to it. |
| What is the vaccine for diphtheria ? | DPT (toxoid vaccine) |
| What are the key features of bordtella perstussis? | gram negative, pleomorphic coccobacilli, STRICT AEROBES |
| What is the "whoop" in whooping cough caused by ? | seconadry narrowing of the air ways |
| What is the toxin formed by bordtella pertusus ? | A-B toxin: ADP ribosylates (inhibits) the G protein that is inhibitor to adenyl cyclase (inhibition of the inhibitor) --> increase cylic AMP. This results in inhibition of phagocytosis and death of cilliated epithelium |
| Clinical findings of whooping caught | paroxysms of cough followed by inspiratory whoop (due to airway narrowing), emesis, and seizure sometimes present. |
| What are the 3 stages of whooping cough ? | Initial catarrhal: indisting. from other URIs: this is the most contagious phase. 2nd parox stage: intense coughing lasting several min. under 6mos old may not have whoop. 3rd parox stage: chronic cough for weeks. old people may not show distinct stages. |
| CBC finding of whooping caught? | **lymphocytopenia** |
| Whooping cough is best dx'd via ... | direct flourescent antibody (DFA) |
| What viruses commonly cause colds during the summer? | Rhinovirus (over 50% of the colds seen during summerm onths) Also major agent of winter colds. Adenovirus is second most common cause of summer colds |
| Most common agent of the common cold? | rhinovirus |
| Increase in nasal secretion of what cytokines correlate with cold symptoms ? | IL-8 and Kinins |
| What is the cause of nasal secretion (runny nose) seen with a cold ? | Increased vascular permeability |
| Describe key features of rhinovirus ? | Picornaviridae: (+)ssRNA. Naked icosahedral capsid. 30 nm. Early fall to late spring but still acount for over 50% of summer colds. |
| Describe the key features of coronavirus? | Coronaviridae : (+)ssRNA, enveloped pleomorphic (100-150 nm). Winter to spring seasonality. |
| Describe the key features of influenzae virus | Orthomyxoviridae: segmented (7-8) (-) ssRNA, Evenloped spherical, 120nm, Winter to early spring. Wide host range: birds, swine. humans |
| What are the common viral causes of colds and pharyngitis ? | Coronavirus, influenza A & B (orthomyxoviridae), rhinovirus (picornaviridae). |
| Pharyngitis in children under 3 is almost always due to... | viral infection |
| Compare the duration of pharyngitis to the common cold... | pharyngitis = 3 to 7 days. Common cold = 1 to 2 weeks |
| List three factors thats can inhibit alveolar macrophages? | alcohol, hypoxemia, hyperoxemia, cigarette smoke |
| What are the two major classes of pulmonary injury? | pneumonia: inflammation within the aleolus itself and interstitial pneumonitis: typically confined to the interstitium, but may spread to involve alveoli (diffuse alveolar damage). |
| What are common agents of interstitial pneumonitis? | M. tuberculum and viruses |
| Why are cases of interstitial pneumonitis not commonly seen? | because it is a self limiting disease. Recovery occurs fairily quick |
| What type of influenza is most commonly involved in pandemic/epidemic flu outbreaks | Influenza A |
| Compare influenza A to influenza B... | inf. A: unique protein = M2, human, swine, avian, or marine animal borne. Common agent of epidemic flu outbreak. Var. by ANTIGENIC DRIFT and SHIFT Influ B: humans are only vector, unique protein = NB. Var. by ANTIGENIC DRIFT ONLY. *BOTH HAVE 8 SEGMENTS* |
| What virus is M2 protein found in? What is it's function? | found in Infuenza A. M2 is an ion channel |
| What are the virus specific glyproteins of influenza A? | M2, hemagglutin (agglutinates RBCs in vito and functions as attachment to N-acetyluramic acif on host cells. |
| What is the function of neuroaminidase ? | glyoprotein of INfluenza A that aids inthe release of newly formed virus particles form the infected cell |
| What is the difference beween antigenic shift and antigenic drift? | shift: major change (>50%) in H & N due to *RE-ASSORTMENT* Occurs when two different strains of virus infect the same cell.(example: H3N2 + H1n1 -> H3N2, H1N1, H1N2, H3N1) ; DRIFT: subtle antigenic changes in H&N of strains. Only Slight diff from orginal |
| What is the H5N1 strain ? | bird flu. No human to human transmission Due to direct contact with chickens |
| How effective is antibiotic prophylaxis of superinfectiion secondary to viral infection | not very effectove! |
| What are amantidine and ramantidine used for? What is their mech ? | short term prophylaxis against influenza. They work by blocking the M2 channel thus inhibitting uncoating and virion assembly. |
| What treatments are available for influenza | amantadine, romantadine (short term prophylaxis) neuramidase inhibitors: zanamavir, tamaflu (oseltamivir). Only effective if give early on. KILLED VACCINE = VACCINATION |
| FAtal cases of H1N1 flu (swine flu) are commonly due to: | secondary staph aureus infection. |
| Rx for H1N1 flu ? | neuraminidase inhibitors. (must be started early on) |
| Dx os H1N1 swine flu? | antigenic test for influenza A confirmed with RT-PCR |
| Blackened hilar lymph nodes is a common finding of... | smoking |
| What does the H and the N in H1N1 (H2,N1; etc...) ? | Hemoglutting and Neuroamidase. H-1,2, and 3 and N-1 and 2 are the the most important H's and N's |
| What type of antigen variation is responsible for epidemics? What kind is responsible for keeping the virus circulating from year to year? | epidemics are caused by *genetic shift*. Viruses are kept active from year to year by genetic drift |
| What kind of cough is characteristic with influenza infxon? | DRY cough *non-productive* |
| What is the incubation period of influenza ? | 2-3 days |
| What is reye's syndrome ? | Cerebral edema and fatty infiltration of liver. Seen in infant & children. *Caused by giving aspirin to children in treatment of influenza* |
| In general, intracellular pathogens (ie viruses) are controlled by what type of immune response? | cell mediated... interferon/cytotoxic T-cells. |
| Describe Respiratory Synctial Virus | RSV is in the paramyxovirus family, it produced cell fusion ** in vitro AND IN-VIVO**(synctium), ENVELOPED (-)ssRNA, NON-segmented. *contains no hemogluttin or neuroaminidase. Causes bronchiolitis and pneumolitis in infants, elderly and immunocomp'd |
| What virus is a major problem on pediatric wards and causes bronchiolitis and pneumolitis in infants? | RSV |
| **What determines the severity of RSV infection? ** | The degree to which Th2 response is posted. High Th2 response causes a more severe disease** |
| WHo are at highest risk of fatality due to RSV infection ? | pediatric patients on Chemo (ALL, etc) |
| Incubation period of RSV? When are peak symptom severity seen? | 2-4 days. Peak symptoms seen in 1-3 days. (very fast onset) |
| Most effective method for RSV dx? | rapid immunofluorescence or immuno assay |
| Describe the BVZ virus | Herpes varicella zoster. Causes chickenpox in children, shingles in adults. ENVELOPED LARGE DNA VIRUS |
| All herpes viruses are... | large enveloped virus |
| What is zoster? | shingles. |
| Major complication of zoster? | Post herpetic neuralgia (PHN). Severe pain for months to years following a herpes outbreak. Common in cancer pts or dehabilitated pt |
| What is a tzanck smear? | Detects multinucleated cells with viral inclusions due to herpes virus. Used in dx of herpes. Does not distinguish HZV from herpes simplex |
| When performing a tzanck smear, where is the sample taken? | vessicle must be scraped in a manner that collects from the bottom of the vessicle to ensure collection of *polykaryons with viral nuclear inclusions* |
| Fatality due to HZV related respiratory damage, what disease | pneunonitis |
| Descibe key features of adenovirus ? | DsDNA. Naked, so it replicated in nucleus of human cell. |
| What does adenovirus cause ? | Can cause Respiratory, GI, and systemic disease. Respiratory can mimic strep, otitis media or cause tracheitis or LRI. Most cases self limited. No vaccine or tx available |
| Describe Hantavirus. | Bunyaviridae family. Eveloped, (-)ssRNA virus. Zoonotic - transmitted from deer mouse in desert regions- with no human to human xmission. Causes hantavirus pulmonary syndrome. |
| Clinical presentation of hantavirus | Fever, myalgia, headache, vomiting, cough. Can rapidly progress to ARDS |
| What virus causes SARS ? | a coronavirus SARS-CoV. |
| Clinical presentation of SARS. | Fever, dry cough, SOB, progressive pneumonitis |
| Vector of SARS? | Palm civets. USed a soup popular in guangdong china |
| Describe CMV? | Cytomegalovirus. A beta-herpes virus. Very large (300 genes!), enveloped, DsDNA. Mostly assymptomatic in healthy individuals (70% of people are seropositive by age 50). Serious life threatening illness in IC pts and neonates. |
| "Owl-Eye inclusion* in cells seen in a pulm. bx. Dx? | CMV infection. 1) Bronchiectasis. |
Created by:
rkirchoff
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