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Micro- Respiratory infxon

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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