URT Bugs Flashcards
what bugs are part of the normal flora?
- diphtheroids (gram + rods)
- alpha/gamma strep
- Neisseria spp.
what are 3 URT protective mechanisms?
- nasal hairs
- mucociliary elevator
- sIgA
what URT infections are found in adults?
- sinus infections
- chronic sinusitis
- pharyngitis
- epiglottitis - rare
- diphtheria - very rare
what URT infections are found in kids?
- pharyngitis
- acute otitis media
- sinusitis
- epiglottitis
- diphtheria
what are the top 3 most common URT infections overall?
- sinus infections and chronic sinusitis (adults)
- pharyngitis (kids)
predisposing factors for acute otitis media
- daycare
- sibling w/ otitis media
- parents smoking
- drinking from bottle on back
- males
physical findings for otitis media?
- otorrhea
- bulging tympanic memb w/ cloudy or yellow fluid behind it
- tympanic memb = red
- local ear pain
- FEVER
signs & symptoms for acute otitis media in a young child?
- crying
- irritability
- anorexia
- lethargy
- hx of pulling at ear
what signs & symptoms would be seen w/ otitis media in an older child/adult?
- earache w/ or w/o drainage
- febrile
- vertigo, tinnitus, decreased hearing
what are the 3 major bacterial pathogens for URT infections?
- Strep pneumo
- H. flu
- Moraxella catarrhalis
- these are the same 3 that are involved in sinusitis
strep pneumo lab results?
- gram (+) cocci (lancet-shaped)
- alpha hemolytic
- optochin sensitive
- bile soluble
- has polysaccharide capsule that cause B cell immune response
what is the virulence factor for strep pneumo?
- capsule
- helps w/ attachement and prevents phagocytes from grabbing it
what are the available strep pneumo vaccines?
- PPSV23 = polysaccharide vaccine
- conjugate vaccines = PCV7 & PCV13
PPSV23 vs. PCV13 vaccines
PPSV23 = adults 65+, polysaccharide vaccine PCV13 = pts 6 weeks-71 months, age 19+ w/ IC conditions, NOT recommended for healthy adults, conjugate vaccine = incorporated protein
Haemophilus influenza lab results? what does it grow on? what factors does it need?
- gram (-) coccobacillus
- grows on chocolate agar
- needs factors X and V
what is the H. flu virulence factor for the vaccine?
- capsule
- only encapsulated forms are covered by the vaccine NOT the forms that cause AOM
what kind of H. flu causes AOM: capsulated or non-encapsulated? what other type of infections can this cause?
- non-encapsulated H. flu causes AOM
- also can cause eye infections
H. flu causes unilateral or bilateral AOM in kids?
bilateral
symptoms of H. flu epiglottitis
- acute, severe cellulitis of epiglottis
- abrupt onset –> epiglottis swells
- acute inflammation
- edema with infiltration of PMNs
- considered a true EMERGENCY
what is the presentation of H. flu epiglottitis in kids?
- boys age 2-3
- high fever, sits forward drooling
- cherry red epiglottis
- tachypnea
- auscultation = inspiratory stridor, expiratory rhonchi
what are the other possible bugs that cause epiglottitis besides H. flu type b?
- staph aureus
- strep pneumo
- strep pyogenes
what are the virulence factors for H. flu?
- capsule = #1
- IgA protease
- endotoxin: associated w/ LPS; intrinsic part of gram (-) cell wall
characteristics of the H. flu capsule
- polyribitol phosphate (polysaccharide)
- type b was most common; now c, f are on the scene
- vaccine is based on type b still
what would be in your ddx with epiglottitis?
- croup
- angioedema
- foreign body aspiration
- retropharyngeal or peritonsillar abscesses
what symptoms differentiate epiglottitis from croup?
- abrupt onset
- child appears toxic; very sick pt
- drooling, dysphagia
- no barking cough (croup)
- check if pt has gotten Hib vaccine
how can you dx epiglottitis clinically?
- neck xray –> enlarged edematous epiglottis w/ normal subglottic space
what is the main priority w/ epiglottitis pts? what is suggested for all peds pts?
- concerned mainly w/ keeping the airway patent
- suggest peds pts be intubated
what are the types of Hib vaccine
- all are conjugated
- PRP-HbOC conjugated w/ nontoxic diphtheria toxin
- PRP-OMC conj w/ outer memb protein of N. meningitides
- PRP-T conj w/ tetanus toxoid
- PRP-D conj w/ diphtheria toxoid
at what age is it suggested to get Hib vaccine?
2, 4, and 6 months of age
what is different about the PRP-D?
- not recommended for kids <12 months
why do you want a conjugate vaccine? what immune response does it activate?
- you use the conjugate b/c the previous polysaccharide vaccine was not providing effective protection
- activates a T cell immune response
what is caused by Haemophilus aegypticus?
- conjunctivitis aka pink eye
lab results for Moraxella catarrhalis? where is it found?
- gram (-) diplococcic
- found in normal flora
what does M. coatarrhalis produce? implication of this?
- produces beta lactamase
- means you can’t use beta lactams to tx it i.e. no penicillins
characteristics of acute LOCALIZED otitis externa
- similar to skin, follicular infections
- intense pain and tenderness
- canal has local erythema, heat, and tenderness over the tragus
- could be preauricular lymphadenopathy
characteristics of acute DIFFUSE otitis externa
- aka swimmers ear
- hot humid climates; hot tub baths
- pain and itching in canal
- canal is erythematous, edematous; sometimes hemorrhagic
MALIGNANT otitis externa
- aka invasive otitis externa
- severe necrotizing infection
- invasion into surrounding tissues including blood vessels, cartilage and bone
- IC pts; elderly, diabetics at risk
- dx by culture
what but most often causes malignant otitis externa?
- Pseudomonas aeruginosa
P. aeruginosa lab results
- gram (-) rod
- oxidase +
- grows on blood, chocolate, MacConkey agars
- lactose non-fermenter
- blue-green pigmentation from pyanocyanin and pyanoveridin
- grape-like odor
what type of infection do you most often get w/ a new piercing?
- P. aeruginosa
- causes destruction of the pinna and you may have to remove some cartilage
- can also cause a keloid to form
abx selection for Pseudomonas
- Pseudomonas is very resistant
- resistance mechs = mutation of porin proteins & production of beta-lactamase
- typically use a combo therapy to tx
causative agents of pharyngitis
- viral = #1 cause
- bacteria
- yeast (Candida)
what are all the bacteria that can cause pharyngitis?
- strep pyogenes, GABHS are top causes
- non-group A strep
- corynebacterium diphtheria
- N. gonorrhoeae
- arcanobacterium hemolyticum = teenagers
- anaerobic bacterial spp. = very smelly
what makes streptococcal pharyngitis different from viral pharyngitis?
- winter, early spring
- peak in ages 5-11
- abrupt onset
- FEVER
lab results for strep pyogenes?
- gram (+) cocci
- beta hemolytic
- catalase (-)
virulence factors for strep pyogenes?
- M protein
- pyrogenic exotoxins = Spe’s and superantigens
other virulence factors for strep pyogenes?
- hemolysins: lyse RBCs; streptolysin O = ASO titer is good for dx; streptolysin S
- hyaluronic acid capsule
- enzymes: hyaluronidase = can break down their own capsule; streptokinase = useful for clot busting
what is weird about the M protein strains and the protective antibodies?
- your body will only make antibodies for the one type of M strain it was exposed to
- you will not be protected from any other M strains
recall the JONES criteria for dx rheumatic fever
J = joints O = heart (carditis) N = nodules E = erythema marginatum S = syndenham chorea
nephrogenic strains of strep pyogenes
- can be skin or pharyngitis
- kids age 6-10
- immune complexes deposited in kidney
- onset of acute post-streptococcal glomerulonephritis (APSGN) 10d after pharyngitis and 3wks after cellulitis
- type III HS rxn
symptoms of nephritic syndrome
- hematuria = “cola-colored”
- mild proteinuria
- edema = periorbital, abdomen, feet, ankles, hands
- HTN
virulence factors for strep pyogenes
- major mech = in situ immune complex formation d/t deposition of streptococcal nephritogenic antigens w/in glomerulus
what antigens are virulence factors for strep pyogenes?
- NOT M protein
- NAPlr = nephritis-associated plasmin receptor
- SPE B = associated w/ a lot of the pathologic manifestations
- possible that separate antigens are responsible in different people
tx for strep pyogenes?
- no specific tx
- relieve symptoms: blood pressure meds; diuretics
strep pyogenes lab results
- gram (+) cocci; beta hemolytic
- streptozyme test = gives you everything
pyrogenic exotoxins = Spe
- formerly “erythrogenic toxins”; now pyrogenic
- four distinct toxins = SPE A, B, C, & F
- lysogenized strains make A, C = superantigens; manifest as scarlet fever
lab results for strep pyogenes
- gram (+) cocci; beta hemolytic on BLOOD agar
- bacitracin sensitive
- PYR positive
what is the other organism that is PYR positive?
Enterococcus
- but they don’t cause sore throat or skin infections
- more commonly they cause UG or GI infections
what is the causative agent for diphtheria?
C. diphtheriae
lab results for C. diphtheriae; lysogenized strains make ?? spread through ??
- gram (+) rod w/ club-like swellings on ends
- lysogenized strains produce exotoxin
- spreads through resp droplets
toxigenic strain of C. diphtheriae
- beta-prophage carrying tox gene
- DTxR = diphtheria toxin repressor; iron regulated i.e. low iron –> high toxin production
- induces necrosis = formation of pseudomembrane
- 10-20% develop myocarditis
clinical signs & symptoms of diphtheria
- low grade fever, sore throat, malaise
- pseudomembrane: initially white and smooth; later becomes gray w/ patches of green and black necrosis; bleeds upon removal = DANGER b/c toxin gets into the blood
- cervical adenopathy and swelling; “bull neck” = BUZZ
what about giving vaccines to kids w/ diphtheria?
- don’t give vaccines while they are sick
- you want to vaccinate once they are healthy again
epidemiology of diphtheria
- droplet spread
- uncommon in developed countries
- suspect in unimmunized pts w/ rapidly spreading tonsillar exudate
clinical dx of diphtheria
- presence of pseudomemb that bleeds on removal
- deficits in CN IX & X
- EKG changes
lab dx for diphtheria
- loeffler’s or tellurite selective media
- modified ELEK test
- PCR for tox gene, ELISA for toxin, immunochromatography for toxin
tx for diphtheria
- abx = penicillin and erythromycin
- give antitoxin
prevention of diphtheria
- vaccination = toxoid
- DTaP –> kids get 5 doses
- Tdap –> adulescents, adults single dose; anyone going to be around babies has to get it to prevent spread of pertussis
- DT –> no pertussis part
- Td –> 10 yr booster for adolescents/adults
gram stain and shape of Bordetella pertussis
- Gram (-) coccobacillus
virulence factors for pertussis
- filamentous hemagglutinin
- pertactin
- pertussis toxin
- adenylate cyclase toxin
- other toxins = tracheal cytotoxin –> cough/fever
filamentous hemagglutinin
allows binding to ciliated cells of trachea
pertussis toxin
- ADP ribosylation of Gi
- causes fluid/mucus buildup
adenylate toxin
- increases conversion of ATP to cAMP
- causes fluid/mucus buildup
pertactin
- binds to ciliated cells in trachea
tracheal cytotoxin
- causes cough
- stimulates IL-1 which causes fever
prevention of pertussis
- whole-cell inactivated vaccine: can cause neurological s/e especially
- acellular vaccine = less s/e; currently recommended; has pertussis toxin + FH, fimbriae, pertactin –> the organism won’t be able to bind OR produce toxin
what vaccines are available for pertussis?
- DTP
- DTaP
- Tdap –> now given to prego women in 3rd trimester, family members and caregivers; the mom passes antibodies to the baby until they are old enough to get the vaccine
dx of pertussis
- nasopharyngeal aspirate best
- Regan Lowe charcoal medium –> inoculate at bedside
- DFA (direct fluorescent antibody) staining
- PCR = best if available
tx of pertussis
- ID contacts –> erythromycin; immunize
- hospitalize w/ supportive care
- DOC = erythromycin x 14d
what are other Bordetella bugs that cause infections?
- B. parapertussis = milder whooping cough; no pertussis toxin produced
- B. bronchiseptica = usually animal pathogen (kennel cough, rabbit snuffles, atrophic rhinitis in pigs); rare human infections –> assoc w/ animals, some underlying diseases
