Term
| is respiratory illness the leading cause of acute morbidity/visits to a physician? |
|
Definition
| yes - ranging from a common cold -> pneumonia |
|
|
Term
| what are a majority of infectious respiratory illnesses due to? |
|
Definition
|
|
Term
| what are the most severe respiratory illnesses typically? |
|
Definition
|
|
Term
| can viral respiratory infections lead to a secondary bacterial infection? how might this occur? |
|
Definition
| yes, viral infection or allergic response can predipose the host for superinfection by bacteria. viral infections cause inflammatory responses/edema that lead to obstructions of the airway that favor bacterial colonization. the ciliated epithelial cells are often specifically damaged - which leads to impairment of mucociliary transport |
|
|
Term
| how does the type of virus or bacteria differ in importance in respiratory infection of one vs the other? |
|
Definition
| specific viruses are not usually identified b/c there is no specific tx and thus the general symptoms are what therapy is designed to target. however, tx for respiratory bacterial infection is dictated by the type of bacterial pathogen as |
|
|
Term
| what are the most common infections caused by viruses? |
|
Definition
| rhinoviruses (colds), pharyngitis, laryngitis, laryngotracheobronchitis (croup), tracheobronchitis, bronchitis, and bronchiolitis |
|
|
Term
| what are the most common infections caused by bacteria? |
|
Definition
| pharyngitis, sinusitis/rhinosinusitis, otitis, epiglottitis, and pertussis (whooping cough) |
|
|
Term
| can both viruses and bacteria cause pneumonia? |
|
Definition
| yes, though bacterial pneumonia tends to be more severe |
|
|
Term
| where do bacterial pathogens infecting the respiratory tract come from? |
|
Definition
| bacterial pathogens infecting the respiratory tract can simply be resident flora (this + obstruction commonly leads to sinusitis and otitis media) or transient colonization by more pathogenic organisms can take place via inhalation of aerosols, where smaller particles can deposit lower in the RT and altered host defenses leads to clinical disease. (*the smaller the particle - the lower in the RT it will deposit*) |
|
|
Term
| what are anerobic resident bacterial flora that may cause RT infections? |
|
Definition
| peptostreptococcus, fusobacterium, veillonella, actinomyces, and bacteriodes |
|
|
Term
| what are aerobic resident bacterial flora that may cause RT infections? |
|
Definition
| nonpathogenic streptococcus and neisseria, non typable haemophilus influenzae, and moraxella catarrhalis |
|
|
Term
| what are occasional or transient bacterial flora that may cause RT infections? |
|
Definition
| str pyogenes, str pneumoniae, and n meningitidis |
|
|
Term
| what is the most important cause of pharyngitis? |
|
Definition
|
|
Term
| what bacteria are commonly associated with pharyngitis? |
|
Definition
| *str pyogenes, corynebacterium diptheriae, mycoplasma pneumoniae, and chlamydia pneumoniae |
|
|
Term
| what bacteria are commonly associated with otitis media? |
|
Definition
| str pneumoniae, haemophilus influenzae, and moraxella catarrhalis (normal flora of nasal passages, can become pathogenic w/obstruction) |
|
|
Term
| what bacteria are commonly associated with otitis externa? |
|
Definition
| staphylococcus aureus, str pyogenes, pseudomonas aeruginosa, and aspergillus/candida |
|
|
Term
| what are the most common causative organisms associated with community-acquired rhinosinusitis? |
|
Definition
| same as otitis media - str pneumoniae, haemophilus influenzae, and moraxella catarrhalis (normal flora of nasal passages, can become pathogenic w/obstruction) |
|
|
Term
| what are the most common causative organisms associated with hospital-acquired rhinosinusitis? |
|
Definition
| gram negative bacilli - pseudomonas aeruginosa, *klebsiella, proteus, enterobacter, and staph aureus - have to worry about antibx resistance |
|
|
Term
| what is the bacterial cause of epiglottitis in children 2-6 yrs? |
|
Definition
| haemophilus influenzae *type b* - to which there is a vaccine |
|
|
Term
| what symptoms are associated with a cold? |
|
Definition
| stuffy nose, sneezing, rhinorrhea (runny nose), general malaise, headache, watery eyes, sore throat, fever (depends on severity), cough (if pathogen spreads to trachea & bronchi or due to postnasal drip) |
|
|
Term
| how can bacterial and viral causes of colds be differentiated? |
|
Definition
| viral infections: clear, mucoid nasal secretions. bacterial infection: mucopurulent secretions (often secondary to viral infection and can spread to the ears and sinuses) |
|
|
Term
|
Definition
| inflammation or infection of the nasal passages and sinuses (cold symptoms, facial pressure/pain, and headache) |
|
|
Term
| what defines acute rhinosinusitis? |
|
Definition
| most colds that involve both the nasal passages & sinuses. 1-2% are complicated by bacterial infections. |
|
|
Term
| what defines chronic rhinosinusitis? |
|
Definition
| >8 wks or >4 episodes a year lasting more than 10 days - usually due to bacteria or fungi |
|
|
Term
| what is bacterial rhinosinusitis usually preceded by? |
|
Definition
| acute viral rhinosinusitis and allergic rhinits that lead to excess mucous secretions or obstructions - allowing overgrowth of bacteria |
|
|
Term
| what are risk factors for bacterial rhinosinusitis? |
|
Definition
| allergies, anatomic factors causing obstruction of sinuses, swimming/diving, smoking, dental infections or procedures |
|
|
Term
| what are the 2 most common causes of bacterial rhinosinusitis? is there a bacteria that specifially causes bacterial rhinosinusitis in children? |
|
Definition
| str pneumoniae and haemophilus influenzae. moraxella catarrhalis is commonly seen in cases of bacterial rhinosinusitis in children. |
|
|
Term
| what characterizes cases of anerobic bacterial rhinosinusitis? |
|
Definition
| anerobic bacterial infections tend to be polymicrobial, associated with dental infections/procedures and are more common in chronic infection |
|
|
Term
| when are gram-negative bacteria more commonly seen causing bacterial rhinosinusitis? |
|
Definition
|
|
Term
| can str aureus and pyogenes cause bacterial rhinosinusitis? |
|
Definition
|
|
Term
| what characterizes noninvasive fungal sinusitis? |
|
Definition
| most commonly aspergillus colonizes immunocompetent pts without invading |
|
|
Term
| what characterizes invasive fungal sinusitis? |
|
Definition
| aspergillus and mucor directly invade bone (rhinocerebral disease) in immunocompromised individuals |
|
|
Term
| what characterizes allergic fungal sinusitis? |
|
Definition
| commonly aspergillus will infect pts with a hx of allergic rhinitis or asthma |
|
|
Term
| what are most cases of pharyngitis due to? |
|
Definition
| viruses, which are self-resolving and rarely cultured |
|
|
Term
| what is the most common bacterial cause of pharyngitis? |
|
Definition
| str pyogenes (group A str, GAS) |
|
|
Term
| how will pharyngeal infections of str pyogenes present clinically? |
|
Definition
| fever, sore throat, tonsillar & pharyngeal erythema - there may or may not be exudate and anterior cervical lymphadenopathy |
|
|
Term
| what are objectives for diagnosing pharyngitis? |
|
Definition
| ID strep throat so the pt can be treated - avoid treating pts w/viral pharyngitis |
|
|
Term
| b/c EBV can cause pharyngitis, how can you differentiate if it is the cause or GAS such as str pyogenes is at root? |
|
Definition
| str pyogenes: yellow exudate, tender cervical lymphadenopathy, sudden onset and soft palate petechiae. EBV: gray-white exudate, splenomegaly, and generalized lymphadenopathy |
|
|
Term
| how is pharyngitis due to GAS such as str pyogenes differentiated from influenza, adenovirus, HSV, enterovirus, HIV, |
|
Definition
| influenza: has a cough, no exudate, no lymphadenopathy. adenovirus: has conjuncitivitis, no exudate, no lymphadenopathy. HSV: has gray white exudate, ulcers, no lymphadenopathy. enterovirus: has a rash, little exudate, little lymphadenopathy. HIV: no exudate, some splenomegaly, and generalized lymphadenopathy. |
|
|
Term
| what are the different kinds of airway infections? |
|
Definition
| croup/laryngotracheobronchitis (mainly viral), epiglotitis (haemophilus influenzae type b), bronchitis & bronchiolitis (mainly viral), pertussis (whooping cough, infection of the trachea - bordetella pertussis), influenza, pneumonia - bacterial/viral infection of the alveoli |
|
|
Term
| what does bacterial pneumonia often follow? what are common symptoms? |
|
Definition
| a flu-like illness or upper respiratory tract infection (viral). common symptoms include: acute onset, fever, chills, productive cough, SOB, and tachycardia (viral pneumonia is usually less severe and has more of a gradual onset) |
|
|
Term
| what is important for diagnosing pneumonia? |
|
Definition
| CXR, on which a defined density, lobular pneumonia indicates typical pneumona, however - diffuse, nondefined infiltrates or interstitial pneumonia indicates an atypical pneumonia |
|
|
Term
| what are common pathogens associated with community acquired acute pneumonia? |
|
Definition
| *str pneumonia, haemophilus influenzae, moraxella catarrhalis, staph aureus, and klebsiella pneumonia |
|
|
Term
| what are common bacterial pathogens associated with community acquired atypical pneumonia? |
|
Definition
| mycoplasma pneumoniae, chlamydia, legionella pneumophilia, and coxiella burnetti (Q fever) |
|
|
Term
| what are common viral pathogens associated with community acquired atypical pneumonia? |
|
Definition
| respiratory syncytial virus, parainfluenza virus, influenza virus, and adenovirus |
|
|
Term
| what pathogens will be seen more commonly in pts with hospital-acquired pneumonia? |
|
Definition
| gram negative enterobacteriaceae, klebsiella pneumonia, serratia marcescens, pseudomonas aeruginosa and staph aureus (MRSA) |
|
|
Term
| what pathogens will be seen more commonly in pts with aspiration pneumonia? |
|
Definition
| anearobic oral flora: bacteroides, prevotella, fusobacterium, and peptostreptococcus. aerobic bacteria: str pneumoniae, staph aureus, haemophilus influenzae, and pseudomonas aeruginosa |
|
|
Term
| what pathogens will be seen more commonly in pts with chronic pneumonia? |
|
Definition
| mycobacterium TB, atypical mycobacteria, and the fungal pathogens: histoplasma capsulatum, coccidiodes immitis, and blastomyces dermatitidis |
|
|
Term
| what pathogens will be seen more commonly in pts with necrotizing pneumonia and lung abcesses? |
|
Definition
| anaerobic bacteria (abscesses are characteristic for these), staph aureus, klebsiella pneumonia, and nocardia asteroids |
|
|
Term
| what pathogens will be seen more commonly in pts with pneumonia in immunocompromized hosts? |
|
Definition
| CMV, pneumocystis jiroveci, mycobacterium avium-intracellulare, aspergillus, and candida. (these are the more opportunistic pathogens) |
|
|
Term
| how do the typical vs atypical pneumonia compare? |
|
Definition
| atypical pneumonia tends to be of a more gradual onset (several days -> 1 wk) and lower temp. (<39.C) coughing is nonproductive, there is no or mucoid sputum (nonpurulent), monocytes are seen in cxs (PMNs are seen in typical) |
|
|
Term
| what is the most common pathogen causing typical pneumonia? atypical? |
|
Definition
| typical: streptococcus pneumoniae, atypical: mycoplasma pneumoniae |
|
|
Term
| what bacteria are common causes of pneumonia in neonates (< 4 wks)? |
|
Definition
|
|
Term
| what are common causes of pneumonia in children (4 wks-18 yrs)? |
|
Definition
| *RSV, mycoplasma pneumoniae, chlamydia pneumoniae, and streptococcus pneumoniae |
|
|
Term
| what are common causes of pneumonia in adults (18-40 yrs)? |
|
Definition
| mycoplasma pneumoniae, chlamydia pneumoniae, and streptococcus pneumoniae |
|
|
Term
| what are common causes of pneumonia in the elderly? |
|
Definition
| streptococcus pneumoniae, viruses, anaerobes, haemophilus influenzae, and gram negative bacilli |
|
|
Term
| what causes of pneumonia are associated with alcoholism? |
|
Definition
| *klebsiella pneumoniae, anaerobes, staph aureus, and strep pneumoniae |
|
|
Term
| what causes of pneumonia are associated with COPD? |
|
Definition
| *haemophilus influenzae, *moraxella catarrhalis, strep pneumoniae, and legionella pneumophila |
|
|
Term
| what causes of pneumonia are associated with poor dental hygiene? |
|
Definition
|
|
Term
| what causes of pneumonia are associated with IV drug use? |
|
Definition
| *staph aureus, step pneumoniae, anerobes, and mycobacterium TB |
|
|
Term
| what are possible causes of pneumonia in HIV infected pts (CD4 count <200)? |
|
Definition
| *pneumocystis jiroveci, histoplasma capsulatum, mycobacterium TB, strep pneumoniae, haemophilus influenzae |
|
|
Term
| what are possible causes of pneumonia in smokers? |
|
Definition
| strep pneumoniae, haemophilus influenzae, moraxella catarrhalis, legionella pneumophilia (similar and often connected to that seen in COPD pts) |
|
|
Term
| what are possible causes of pneumonia in cystic fibrosis pts? |
|
Definition
| *pseudomonas aeruginosa, staph aureus, and burkholderia cepacia |
|
|
Term
| what are possible causes of pneumonia due to outbreaks in military camp? |
|
Definition
| strept pneumoniae, chlamydia pneumoniae, mycoplasma pneumoniae, and adenovirus |
|
|
Term
| what are possible causes of pneumonia due to outbreaks in a jail or homeless shelter? |
|
Definition
| strep pneumoniae and mycobacterium TB |
|
|
Term
| what are possible causes of pneumonia due to outbreaks in nursing homes? |
|
Definition
| strep pneumoniae, chlamydia pneumoniae, influenza A, and RSV |
|
|
Term
| what are possible causes of pneumonia due to contaminated A/C units or hot tubs? |
|
Definition
|
|
Term
| how do the streptococcus spp stain? what shape are their colonies? do they have catalase? |
|
Definition
| streptococci are gram + in chains and are catalase negative (differentiates them from staph) |
|
|
Term
| what is the serological group for strep pyogenes? hemolysis? |
|
Definition
| strep pyogenes is group A serological group and beta hemolytic |
|
|
Term
| what is the serological group for strep agalactiae? hemolysis? |
|
Definition
| strep agalactiae is group B strep and beta hemolytic |
|
|
Term
| what is the serological group for viridans streptococci? hemolysis? |
|
Definition
| viridans strep are not serologically groupable and are alpha hemolytic |
|
|
Term
| what is the serological group for strep pneumoniae? hemolysis? |
|
Definition
| strep pneumoniae are not serologically groupable and are alpha hemolytic |
|
|
Term
| are strep pyogenes sensitive to bacitracin? |
|
Definition
| yes, b/c they are group A |
|
|
Term
| are strep pyogenes PYR positive? |
|
Definition
| yes, l-pyroglutamylaminopeptidase is an enzyme produced by strep pyogenes |
|
|
Term
| does strep pyogenes have a hyaluronic acid capsule? |
|
Definition
| yes, which is an important anti-phagocytic virulence factor |
|
|
Term
| what are the exotoxins/superantigens produced by strep pyogenes? |
|
Definition
| exotoxin A (TSS) and the rash of scarlet fever (erythrogenic toxin) can activate cytokines |
|
|
Term
| does step pyogenes have the M protein? what does this do? |
|
Definition
| strep pyogenes has the M protein which acts as an adhesin, it is anti-phagocytic and inhibits complement. this is an important virulence factors. |
|
|
Term
| what are the functions of streptolysin S and O? does strep pyogenes have both? |
|
Definition
| yes, strep pyogenes uses both streptolysin S and O to lyse leukocytes, platelets and RBCs. ASO titers detect antibody to streptolysin O, which can indicate a recent infection. |
|
|
Term
| what is the function of both streptokinase and the DNases that strep pyogenes codes for? |
|
Definition
| strep pyogenes uses streptokinase to lyse blood clots and DNases to degrade DNA in pus. both of these actions will help increase the spread of strep pyogenes |
|
|
Term
| who is "strep throat" usually seen in? |
|
Definition
|
|
Term
| how does strep throat present? |
|
Definition
| a sudden onset of sore throat, high fver, chills, malaise, and a headache |
|
|
Term
| how does the throat appear upon inspection in pts with "strep throat"? |
|
Definition
| erythematous pharynx, exudate in ~50% of cases, petechiae on the soft palate in some cases, and anterior cervical lymphadenopathy |
|
|
Term
| how common are complications with "strep throat"? |
|
Definition
| rare w/appropriate use of antibx |
|
|
Term
| what are possible complications of strep throat? |
|
Definition
| scarlet fever, streptococcal toxic shock syndrome, rheumatic fever |
|
|
Term
| what happens if strep throat progresses to scarlet fever? |
|
Definition
| scarlet fever can occur if the infecting strain produces a pyrogenic exotoxin. the rash will appear 1-2 after the onset of phayngitis and starts on the chest and spreads to the extremities. the rash then fades over 5-7 days and is followed by desquamation. |
|
|
Term
| what happens if strep throat progresses to rheumatic fever? how is this prevented? |
|
Definition
| rheumatic fever occurs ~2 wks after pharyngitis and presents as fever, migrating polyarhritis and carditis. antibodies may form against the capsule and cross react with the joint tissue and some other antibodies may form against M proteins and cross react with the heart. this is prevented by tx of the GAS pharyngitis with PCN. (antibiotics may be given prophylactically to prevent a 2nd episode of strep throat - damage is cumulative) |
|
|
Term
| can strep infections affect the kidneys? how would this be treated? |
|
Definition
| yes, though acute glomerulonephritis occurs more commonly after skin infections than pharynitis. acute glomerulonephritis (AGN) is caused by antigen-antibody complexes in the kidney, but the M serotypes associated with AGN are different than those associated with RF. this can only be prevented by antimicrobial tx of the initial infection, not after onset of AGN symptoms. |
|
|
Term
| how is a strep throat diagnosed? |
|
Definition
| cx - beta hemolytic, catalase negative, gram + cocci. latex agglutination tests can ID the lancefield grouping or bacitracin/PYR tests. rapid antigen detection assay may also be used in place of a cx. |
|
|
Term
| how are GAS & viral infections differentiated? |
|
Definition
| viral infections are marked by conjunctivitis, a cough, and coryza (cold symptoms) while bacterial infections are more consistent with severe symptoms and tender lymph nodes |
|
|
Term
| what do pharyngitis and conjuntivitis point to diagnostically? |
|
Definition
|
|
Term
| what does a grayish pseudomembrane point to diagnostically? |
|
Definition
|
|
Term
| what do exudates suggest diagnostically? |
|
Definition
|
|
Term
| what do vesicles and ulcers suggest? |
|
Definition
|
|
Term
| what is the most common bacterial respiratory pathogen? |
|
Definition
|
|
Term
| does strep pneumoniae cause infection in both community acquired and nosocomial infections? |
|
Definition
|
|
Term
| what levels of the respiratory tract are affected by strep pneumoniae? |
|
Definition
| sinusitis, otitis media, and pneumonia |
|
|
Term
| what are strep pneumoniae respiratory infections a common complication of? |
|
Definition
| viral respiratory tract infections |
|
|
Term
| how are strep pneumoniae shaped? what kind of hemolysis do they display? |
|
Definition
| strep pneumoniae are alpha hemolytic and lancet-shaped diplococci. |
|
|
Term
| how are the over 90 different serotypes of strep pneumoniae differentiated? how many of these serotypes is the vaccine preventative against? |
|
Definition
| the quellung reaction. 23 serotypes are protected against by the vaccine |
|
|
Term
| is strep pneumonia soluble in bile? |
|
Definition
|
|
Term
| is strep pneumoniae inhibited by optochin? |
|
Definition
| yes (as tested for with the p-disk) - this defines strep pneumoniae as group B strep |
|
|
Term
| what virulence factors does strep pneumoniae possess? |
|
Definition
| capsules (antiphagocytic), IgA protease, pneumolysin (lyses epithelial cells & phagocytes), hydrogen peroxide (tissue damage), and teichoic acid & peptidogylcan (activate the alternative complement pathway, induces cytokine production) |
|
|
Term
| how can strep pneumoniae be confirmed as the cause of sinusitis and otitis media? |
|
Definition
| gram stain and cx of aspirates - strep pneumoniae does not generallly cause bacteremia with sinusitis and otitis media |
|
|
Term
| does strep pneumoniae cause bacteremia with pneumonia? |
|
Definition
| yes, which yields a positive blood cx as well as potential for gram stain and cx from the sputum (want to ensure the sputum sample does not contain skin cells - which is a sign of contamination from the mouth) |
|
|
Term
| is staph aureus a normal component of skin flora? what kind of infections is staph aureus usually responsible for? |
|
Definition
| yes and ~15% of adults are nasopharyngeal carriers of staph aureus - therefore it can cause both community-associated and nosocomial infections |
|
|
Term
| how does staph aureus appear in colony? what is its gram stain? does it have catalase? coagulase? what hemolysis? can staph aureus ferment mannitol? doe it have protein A? exotoxins? |
|
Definition
| staph aureus is gram positive cocci in clusters and is catalase positive. staph aureus is coagulase positive, is beta-hemolytic, ferments mannitol, has exotoxins and protein A (which binds the Fc region of IgG) |
|
|
Term
| what are some of the virulence factors associated with staph aureus? |
|
Definition
| hyaluronidase: lyses connective tissue. staphylokinase: lyses thrombi or clots. lipase: degrades fats and oils. proteases: destroy tissue proteins |
|
|
Term
| what are the types of clinical disease associated with staph aureus? |
|
Definition
| toxin mediated: food poisoning, toxic shock syndrome, scalded skin syndrome. cutaneous: impetigo, folliculitis, furuncles, carbuncles, wound infections. other: endocarditis, bacteremia, *pneumonia, *empyema, osteomyelitis, septic arthritis, *otitis externa |
|
|
Term
| can staph aureus cause infections of the ear? |
|
Definition
|
|
Term
| what characterizes the respiratory infections caused by staph aureus? |
|
Definition
| pneumonia due to staph aureus is often nosocomial and due to: aspiration of oral secretions, hematogenous spread from a distant site, *following influenza, associated with IV drug use, and seen in extremes of age or individuals w/lung disease |
|
|
Term
|
Definition
| empyema is purulent pleural fluid (pleural pus) composed of PMNs and microorganisms due to a complication in pts with pneumonia 2% of the time. empyema is due to a staph aureus infection 10-40% of the time and gram negative bacteria 25-50% of the time. |
|
|
Term
| can MRSA cause pneumonia? |
|
Definition
| yes, MRSA can cause pneumonia - though it is usually considered a skin infection. it is not usually associated with community acquired pneumonia but as a complication of influenza - leading to a necrotizing pneumonia. |
|
|
Term
| what characterizes pneumonia due to MRSA? |
|
Definition
| rapid clinical progression and MRSA being isolated w/in ~3 days of respiratory symptoms. this suggests that influenza and staph aureus infections *occur together b/c the non-MRSA pneumonias generally take longer to set in after the influenza infection |
|
|
Term
| what kind of bacteria is haemophilus influenzae? does it require any particular factors for growth? |
|
Definition
| a *gram negative coccobacillus. haemophilus influenzae requires X factor (hematin) and V factor (NAD) for growth (will grown on chocolate agar) |
|
|
Term
| what virulence factor does haemophilus influenzae posess? |
|
Definition
|
|
Term
| what kinds of respiratory infections does haemophilus influenzae usually cause? |
|
Definition
| children, sometimes adults: sinusitis, epiglottitis, & otitis media. elderly, adults w/chronic pulmonary disease: pneumonia |
|
|
Term
| what characterizes the nonencapsulated/non-typable strains of haemophilus influenzae? |
|
Definition
| these are normal flora of the URT, and can be opportunistic pathogens causing sinusitis and otitis media |
|
|
Term
| what characterizes the encapsulated/typable strains of haemophilus influenzae? |
|
Definition
| there are 6 serotypes (a-f), of which type b was the most pathogenic & prevalent in the prevaccine era (was the leading cause of meningitis in children) |
|
|
Term
| what is the leading cause of epiglottitis? who is usually affected? |
|
Definition
| haemophilus influenzae type b, which can cause epiglottitis in children with poor response to the vaccine/incompletely vaccinated or some adults (rare due to Hib vac). |
|
|
Term
| what characterizes epiglottitis due to haemophilus type b? |
|
Definition
| colonization of the nasopharynx extends to the epiglottis, an inflammatory response produces erythema and edema and the sore throat progresses to difficulty breathing, stridor, and obstruction of airways & respiratory distress. |
|
|
Term
| how do pts with epiglottis due to haemophilus influenzae type b present? what is a caution in terms of diagnosing this? is this considered a medical emergency? |
|
Definition
| pts w/epiglottis due to haemophilus influenzae type b present with acute onset fever, pharyngitis, hoarseness, and a barking cough. *examining the larynx under these conditions can contribute to airway closure and asphyxiation - this is considered a medical emergency. |
|
|
Term
| what are the "4 D's" associated with epiglottis due to haemophilus influenzae type b? |
|
Definition
| dysphagia, dysphonia, drooling, and distress |
|
|
Term
| what are the possible complications due to epiglottis due to haemophilus influenzae type b? |
|
Definition
| bacteremia resulting in meningitis, septic arthritis or osteomyeltis |
|
|
Term
| what happens when pts are not given full Hib vaccination? |
|
Definition
| there is an increase in haemophilus influenzae type b-related deaths, indicating that the pathogen is still present and lethal given the opportunity. (unvaccinated children are still protected by more of the population being vaccinated - keeps rate of transmission down) |
|
|
Term
| what characterizes moraxella catarhallis? |
|
Definition
| moraxella catarhallis is a *gram negative diplococci that can be normal flora in the URT - it is seen in the same kinds of circumstances as haemophilus influenzae |
|
|
Term
| what is clinical disease induced by moraxella catarhallis characterized by? |
|
Definition
| similar to haemophilus influenzae, moraxella catarhallis infections are frequently associated with otits media and community acquired sinusitis and occasionally associated with community acquired pneumonia (more likely in elderly, chronic lung/COPD pts) |
|
|
Term
| what is bordetella pertussis? |
|
Definition
| a small *gram negative coccobaccillus - a *strict anerobe |
|
|
Term
| what kind of respiratory disease does bordetella pertussis usually cause? what is its reservoir? is there a vaccine? |
|
Definition
| whooping cough is caused by bordetella pertussis, which only has humans as its reservoir and spreads via infectious aerosols, it is maintained in the community via unrecognizable infections. there is a vaccine available. |
|
|
Term
| what is the pertussis vaccine that has been used since 1996? |
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Definition
| an acellular vaccine = inactivated pertussis toxin w/1+ bacterial adhesins. it is given in combination with tetanus and diptheria vaccines (DTap/Tdap). |
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Term
| what may be the reason for the recent increase in pertussis? |
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Definition
| possibly a waning immunity in vaccinated individuals or bacterial strains are not recognized by the current vaccine |
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Term
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Definition
| DTaP: higher dose diptheria, tetanus, acellular pertussis vac licensed for use in children (<7 yrs) Tdap: lower dose diptheria, tetanus, acellular pertussis vac licensed for use in adults |
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Term
| what are the virulence factors associated with bordetella pertussis? |
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Definition
| filamentous hemagglutinin & pertacin (which mediate attachment to ciliated respiratory epithelial cells), tracheal cytotoxin (which is cytotoxic for respiratory epithelium), adenylate cyclase (which catalyzes the conversion of ATP to cAMP and inhibits leukocyte chemotaxis, phagocytosis & killing), A-B exotoxin (A: active, subunit 1, B: binding, subunits 2-5) |
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Term
| what is the mechanism of action of the AB exotoxin associated with bordetella pertussis? |
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Definition
| A: active, subunit 1, B: binding, subunits 2-5. S1 *covalently adds ADP-ribose to a membrane G-protein (ADP ribosylation), which inactivates a GTP-binding regulatory protein and prevents deactivation of adenylate cyclase (results in the accumulation of large amounts of cAMP and *increased mucus secretion as well as death and sloughing of ciliated epithelial cells). S2 binds lactosylceramide - glycoprotein on the ciliated resp cell. S3 binds receptors on phagocytes. |
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Term
| what is the incubation period for a bordetella infection? |
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Definition
| 7-10 days, during when the bacteria attach and proliferate on ciliated epithelial cells. |
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Term
| what is the most infectious stage of a pertussis bordetella infection? |
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Definition
| the first 1-2 wks (catarrhal stage), which are usually characterized by cold-like symptoms (runny nose, sneezing, low-grade fever) |
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Term
| when does the coughing associated with bordetella pertussis/whooping cough infection start? |
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Definition
| 2-4 wks - which can lead to vomiting, this is when the disease is often recognized. this is due to a loss of ciliated cells, a thick mucus and impaired mucociliary clearance. |
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Term
| when are cx's for bordetella pertussis more likely to be positive? where is the best specimen likely to come from? does it require a special media to cx? |
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Definition
| earlier on the infection, though it may not be suspected at this point. culturing for pertussis is 100% specific, but only ~50% sensitive. the cx specimen should come from the nasopharyngeal aspirate - oropharyngeal cells aren't helpful (need ciliated epithelial cells). this cx will require a *bordet-gengou media which may take 7-14 days and is sensitive to drying. |
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Term
| what kind of bacteria are corynebacterium diptheriae? |
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Definition
| gram positive rods in V or L shaped formations |
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Term
| does corynebacterium diptheriae have an exotoxin? |
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Definition
| yes, though it is expressed by a lysogenic bacteriophage (beta phage), without which: no exotoxin. the A subunit inhibits the elongation factor 2 (EF-2), shutting down protein synth and the B subunit binds heparin-binding epidermal growth factor on many cells, esp heart and nerve cells |
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Term
| how is the DTap/Tdap vaccine effective against corynebacterium diptheriae? |
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Definition
| the organism can colonize the oropharynx - but cannot cause disease if the toxin is neutralized by the vaccine |
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Term
| what is the reservoir for corynebacterium diptheriae? |
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Definition
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Term
| how does a corynebacterium diptheriae infection present clinically? what is the severe end of the clinical presentation spectrum? |
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Definition
| a sudden onset of exudative pharyngitis (pseudomembranous - bacteria/cell debris/fibrin/WBCs which attach to tonsils/uvula/palate, removal of which can make the tissue bleed) and fever , accompanied by lymphadenopathy ("bull neck" appearance). in severe disease: breathing obstruction, cardiac arrhythmia, coma, and occasionally death may result (rare in US due to vaccine) |
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Term
| how is infection by corynebacterium diptheriae diagnosed? |
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Definition
| infection by corynebacterium diptheriae is diagnosed by the clincal presentation of pseudomembrane and severe cervical lymphadenopathy. the *elek test can be utilized as well as PCR for the tox gene to determine the presence of the exotoxin |
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Term
| what are some of the opportunistic pathogens associated with respiratory disease? what types of circumstances are infections with these pathogens associated with? |
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Definition
| gram negative rods: enterobacteriaceae, pseudomonas (aerobes), and glucose non-fermenters. these are associated with nosocomial infections, CF, alcoholism, and aspiration pneumonia |
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Term
| which of the enterobacteriacea are associated with respiratory tract infections? what is a problem with treating pts with these infections? |
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Definition
| *klebsiella pneumonia*, serratia marcensens, proteus, and enterobacter - to all of which antibx resistance can be a problem |
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Term
| what kind of metabolism does klebsiella pneumoniae have? |
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Definition
| klebsiella pneumonia is a lactose fermenter |
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Term
| what virulence factors does klebsiella pneumoniae express? |
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Definition
| a very thick anti-phagocytic capsule (very mucoid in cx) |
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Term
| what pt population is most affected by klebsiella pneumoniae? |
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Definition
| pts w/predisposing conditions such as: age, chronic pulmonary disease, DM, or alcoholism |
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Term
| what are the most common diseases caused a klebsiella pneumoniae infection? |
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Definition
| UTI and pulmonary disease |
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Term
| what characterizes the pneumonia caused by klebsiella pneumoniae? |
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Definition
| pneumonia caused by klebsiella pneumonia produces a thick, bloody sputum referred to as "currant jelly" sputum |
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Term
| what kind of bacteria are pseudomonas aeruginosa? |
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Definition
| aerobic non-fermenting organisms |
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Term
| where is pseudomonas aeruginosa found? |
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Definition
| pseudomonas aeruginosa is ubiquitous in the environment; soil/moist environments, hospitals (sinks, flowes, water filtering systems, respiratory therapy equipment, and dialysis equipment) |
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Term
| what is a problem with pseudomonas aeruginosa? |
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Definition
| it tends to be resistant to multiple antibx |
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Term
| what characterizes the appearance of pseudomonas aeruginosa? |
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Definition
| there is a sweet, grape-like odor associated with it and it has a blue-green pigment. |
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Term
| what characterizes the polysaccaride capsule of pseudomonas aeruginosa? |
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Definition
| it is alginate w/a slime (mucoid) layer of glycocalyx. this can exacerbate the thick mucus of CF pts and is anti-phagocytic as well as a barrier to antibx |
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Term
| how do pseudomonas aeruginosa infections present clinically? |
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Definition
| pseudomonas aeruginosa can cause RTIs in CF pts, otitis externa (swimmer's ear, can be necrotizing), burn victims, eye of contaminated contact wearers, and UTIs in catheterized pts |
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Term
| what is another important pathogen related to pseudomonas aeruginosa? |
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Definition
| burkholderia cepacia - which also affects CF pts, though has worse prognosis than pseudomonas aeruginosa. CF pts with this infection are kept more in isolation and are often not candidates for lung transplants |
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