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Flashcards in LRT infections Deck (95):
1

primary agent of viral croup (laryngotracheobronchitis)

hPIV (hum. parainfluenza v)
pk: 2-6yo

2

PIV

paramyxovirus, types: 1-->4, no grp. sp. Ag
Hamagglutinin and neuraminidase activity

3

causes of peds bronchitis and pneumonia

1. RSV 2. *PIV* 3. Adenovirus 4. hMPV

4

agents of viral croup

*PIV*, influenza A/B, RSV, hMPB, Ad, non-polio enteroviruses, measles

5

viral croup is the most common cause of what in 6mo to 6 yo children

RT obstruction

6

croup presents with this..
in contrast to acute epiglottitis

SUBglottal edema vs. AE: SUPRAglottal edema

7

in croup..symptoms first manifest here, then migrate here

in URT 1st then larynx, trachea, bronchi

8

croup clin. manifest: Laryngotracheitis

rhinitis first, then sudden onset sore throat, hoarse/bark, stridor, SOB
*steeple sign* (not pathog.)
apprehension, rhonchi, crep, wheeze, dim. BS
*symps vary in intens. last 3-4d if mild

9

other croup clin. manifest:

bronchiolitis-bronchopneumonia

10

major complications of croup

1. Secondary bac laryngotracheitis:
as recov. from viral croup; px w. high fever, toxicity, RD
2. OM

11

viral croup dx

DFA/EIA, viral Cx, direct exam/endoscopy (be careful), NXR ("steeple sign") to ddx from virus-like, bac., AE, airway obstr, asthma

12

viral croup tx

supportive
oral/IM dexamethasone (better than neb. budesonide) or racemic epinephrine (bronchodilate)
*NO VACCINE* for viral croup

13

this is the most common infection of LRT in infants & leading cause of hosp. in childhood...
and the #1 agent is..

bronchiolitis
RSV

14

is chronic bronchitis an infectious disease?

no (inflamm), but low #s may be present
def: dyspnea, airflow limit, sputum production, chronic prod. cough (3mo/year for 2 yrs)

15

is COPD an infectious disease?

no (inflamm), but low #s may be present
reduction in FEV1:FVC

16

AE-CB or AE-COPD

acute exacerbation; frequently causes by viral/bacterial inf. disease

17

neonate acute inf. bronchiolitis (AIB) agents

Strep agalactiae, E. coli, Klebsiella pneumoniae, Ureaplasma urealyticum, and U. parvum, Chlamydia trachomatis

18

infants/young kids: inf. bronchiolitis (AIB) agents

primarily VIRAL:
RSV*, hMPV, influenza v*, PIV, Ad, HBoV, Rhinovirus, coronavirus
much less bac: B. pertussis, Mycoplasma pneumo, Chlamydia pneumo

19

sig. manifest. of AIB

tachypnea, wheezing
NO PNEUMONIA: only scattered wheezing at lung base, but clear lung field

20

bronchitis and bronchiolitis: infectious diseases?

may or may not be

21

bronchitis common etiology: viral or bac?

viral more common: (RSV, influenza, etc)
bac: Mycoplasma pneumo, Chlamydia pneumo, Bordetella pertussis

22

bronchitis prodrome

URT s/s: ha, sore throat, coryza then LRT symps: cough (if prod: sloughing of tracheobronch. epi) +/- bronchospasms, SOB, etc

23

distinct bronchitis negatives

NO FEVER (typically, or low)
NO tachycardia, tachypnea
NO pneumonia: clear CXR, no rales, no egophony, *scattered wheezing @ base

24

bronchitis tx: abx?

NO! not for immuncomp pts, also NO antivirals
*if Dr. decides on abx: macrolide, may decided on antivirals for susp. influenza otherwise tx: bed, fluids, cough suppressants, expectorants

25

AE-CB and AE-COPD bac pathogens:

NTHi**, Moraxella catarrhalis, Strep pneumo

26

AE-CB, AE-COPD: more commonly exacerbated by bacteria or virus?

bacteria! freq. a new strain
if virus: influenza*, RSV
other cause: allergies, immpath

27

how to dx AE-CB/COPD

bronchoscopy spec. collection: Cx, sens.
>10^3 CFU/mL of agent needs to be det.

28

AE-CB/COPD: abx?

no evidence that can prevent, complex decision

29

the most important agent of LRT infections in infants?
characteristics...

RSV:
paramyxovirus, F and G surface glycoproteins
strain A* and B (A is the more virulent strain)
danger!: high attack rate (95%), no vaccine

30

ped. pneumonia, bac or viral more common?

90% viral (50% of that is RSV)
all kids have been inf. w/ RSV by 2-3 yrs

31

RSV is #1 cause of these in infants

LRT diseases: bronchitis, bronchiolitis, pneumo
RSV bronchiolitis can lead to asthma

32

these kids are especially at risk for RSV-caused pulm disease

premature and underlying disease(cardiac, resp, cong: pulm HTN, CLD edt.), American Indian infants
and disease will be more severe

33

RSV affects adults as

reinfection: common cold, minor URT disease

34

RSV affects elderly w/

COPD/CB, immune comp. (organ transplant), LRT disease
*cause bronchopneumonia

35

LBW
VLBW
ELBW

36

RSV patho. (bronchiolitis)

virus replicates in resp. epi (nasal, throat, bronchi)-->syncytia formation-->necrosis-->sloughing of epi-->inflammation, edema-->inc. sec. or mucus from epi-->obstr. airflow
*immpath exacerbations:
type 1 hypersent. to viral AG (IgE) and rel. of mediators

37

RSV bronchiolitis manifestations (infant)

rhinorrhea, cough, NO/LOW GRADE FEVER( + suggests 2 bac inf), dyspnea, cyanosis +/- exp. wheezing/emphysema, hyperinflation, atelectasis
-inc. AP chest diameter, tachy x2, wheezing (whistling), retraction, hepatosplenomegaly

38

RSV bronchiolitis CXR findings

inc. AP diameter
loose floppy diaphragm

39

RSV bronchiolitis: self-lim? tx?

is self-limited, but do tx

40

reinfect. pres

children: sev. rhinitis and pharyngitis (lim. bronchi)
adults: afebrile rhinitis, viral pharyngitis
elderly: ARDS-->viral pneumo

41

RSV bronchiolitis lab collections

nasopharyngeal sec, resp asp. w/ epi cells-->DFA/IF/ELISA

42

RSV bronchiolitis tx: antiviral?

YES: Ribavirin: broad-spec. antiviral (inhib capping and elong. of viral RNA): improv. O2
also: aeorosolized bronchodil. w/ IV theophylline
corticosteriods, mucolytics (Dornase alpha)
*MAINTAIN AIRWAYS* keep air moist`

43

give passive immunization therapy to pt. presenting w/ RSV bronchiolitis?

NO! it only works for prevention
RSV-IGIV, Anti-RSV MoAb (Palivizumab, Motavizumab)*to replace the IGIV
-give ev. mo. to premie infants/infants w. CLD
*NO VACCINE CANDIDATES

44

hMPV (hum. Metapneumovirus)

paramyxovirus
causes dis. sim to RSV, but more mild

45

HBoV (hum. Boca virus)

family: Parvoviridae (B19)
causes both URT/LRT inf.
*pk incidence MARCH-MAY no inf. Aug-Sept.
-pertussis-like syndrome, diarrhea*

46

causes of whooping cough..
where affected?
when?

Bordetella pertussis ("pertussis")
tracheobronchial tree
*LATE SUMMER/EARLY FALL
high attack rate! affects infants*/y. kids

47

Bordetella pertussis

sm. aerobic G-rod, ox +
Pertussis TOXIN (PT)-->ADP ribosylation of GTP BP-->LYMPHOCYTOSIS-->PT induces prot. Ab
(7-16 d incubation) non-invasive and exotoxin (exc. PT) remain localized

48

hallmark of pertussis

LYMPHOCYTOSIS (entrapment in vasc/lymph compartments): 12-20,000 per mm3

49

other factors of pertussis: FHA, Pertactin, TCT

FHA (filamentous hemagglytinin): adherence factor, acts w/ PT to induce leukocytosis/ prot. Abs
Pertactin (69 kDa protein): adhesion, ind. Ab
TCT: (Tracheal cytotoxin) + endotoxin induce NO production-->kills ciliated epi cells

50

pertussis epidemics occur every 2-5 yrs despite vaccinations! main reason:

circulating strains w. INCREASED VIRULENCE ("breakthru" strains)
other reasons: vaccine failure, failure to comply w/ immun., waning adult immunity

51

the most commonly rep. vaccine-prev. dx in kids

Pertussis

52

damage by pertussis exotoxin

to ciliated epithelium:
aggr bac in cilia, sticky mucus, PMN accum.
dec. act/loss of cil. epi, prod. of fluid/mucus/eduma

53

does pertussis vaccination/disease confer immunity?

YES: prolonged (7-20 yrs) but not permanent

54

Pertussis stages: Cartarrhal

highly inf., URT cold-like disease (cough, slight fever, etc) 1-2 wks
Cx/abx effective here but NOT INDICATED
Cx would be done via aspiration > Dacron nasopharyngeal swab, DFA

55

Pertussis stages: Paroxysmal/spasmodic

classic, 4-6 wks, 5-10 coughs + mucus then inspirational "whoooop"!, +/- vomiting, apnea, lymphocytosis* in kids, NO FEVER** (unique for bac inf) few syt. signs--> need hosp.

56

Pertussis stages: Convalescent

gradual, cough dec. (may continue 2-6 wks)
superimposed viral resp inf. can trigger recurrence

57

differences in adult pertussis

paroxysmal cough (>14d), NON-PRODUCTIVE, worse at night, PERIPH. LYMPHOCYTOSIS IS RARE

58

breakthrough pertussis infections in vaccinated children due to

high virulence of B. pertussis

59

complications of pertussis

secondary bac. pneumo (main cause of mort)
toxic enceph. or anoxia
substn. weight loss/sleeping problems

60

pertussis tx: abx?

YES, but only effective @ catarrhal stage
eryth, clarith, azithromycin or TMP-SMZ

61

pertussis: vaccine?

YES:
DTP: P: whole cell (SE: fever, NOT rec. for kids w. seizure/neuro risk), 5 doses, last 4-12 yrs
DTaP/dTaP: aP: acellular, 5 doses: 2,4,6 mos then 12-15 mos and 4-6 yrs, 6 yr duration (need adult booster)
*protective by 1 wk post vaccine*

62

pertussis close contacts: vaccine or abx?

abx ppx

63

influenza virus
+ typing

orthomyxovirus, 3 types: A*, B*, C : all have both envelope glycoproteins (H and N), but stereotyping only done for A
(Hemagglutinin: attachment, Neuraminidase: entry into uninf. cells, del of new virus from infected cells)
H1,2,3 and N1,2 (so 6 variants total)

64

antigenic drift

minor change: point mutation for H or N genes, occurs in both A and B types
may cause epidemics

65

antigenic shift

MAJOR change due to recombin. event for H genes
ONLY in type A (mult. animal hosts-->new viruses for which humans have no herd immunity)
may cause pandemics

66

influenza deaths occur most in...

the young and the old (65)
and medically compromised

67

variant viruses

typ. circulate in swine but cause sporadic human infection
H1N1v, H3N2v*, H1N2v
*most do not result in human to human spread

68

influenza and kiddos

2-10x more susc. than adults BUT typ. less ill and rarely die, so not vaccinated
-serve as reservoirs-->infect adults/elderly (higher mortality)

69

other influenza risk factors (besides age)

pulm/CV disease (COPD, CD, CHF), pregnancy, neurological, neumomuscular disorders (aspiration)

70

influenza comprimesse this imp. defense mech of RT

destruction of ciliated columnar resp. epi (esp. lg airways)

71

immunity in influenza

CMI (CTLs+ IFN prod)-->recovery
Humoral (IgA2 to HA and NA)-->protects against reinfection

72

influenza distinct manifestations

ABRUPT onset (no prodrome) (vs. M/C pneumo)
infants 1: URT dis
***HALLMARK: PERSISTENT HIGH FEVER*** (>100)
-non-prod cough, chest discomfort, ha, myalgias, prol. convalescence (1-2 wks)

73

major cause of mortality in influenza

secondary bac. pneumonia: asp. of throat flora
orgs: Strep pneumo, Staph aureus, Hib
another complication: primary influenza viral pneumonia

74

influenza: abx?

NO! will predispose pt to sec. bac pneumo!!

75

influenza complication in kids admin. ASA

Reye's syndrome : hepatitis, encephalopathy

76

DO NOT give ASA to tx

influenza virus A or B, VZV
(use acetaminophen instead)

77

other complications of influenza

CNS (enceph.) or PNS (Guillain-Barre's)
cerebrovascular, cardiac, OM*, sinusitis

78

influenza lab dx

EIA/DFA, Cx, Hemagglutination inhibition

79

vaccination will not end outbreak if..

incubation period is LESS than time needed for primary immune response (7-10 days for flu)
ALSO antiviral tx is NOT effective for vaccination (resistance may occur)

80

no longer recommended antivirals for influenza

Amantadine, Rimantadine (against A, block m2 protein)

81

influenza antivirals against which types?
inhibit what?

A and B (7yo, ppx>5 yrs
(less resistance to Zanamivir)
Oseltamivir (Tamiflu): tx/ppx >1yo

82

influenza: vaccine?

YES: "good fit" vaccines, Oct-mid Nov (wanes by summer, Feb for elderly)
heterosubtypic immunity is poor; vacc. ind. can still get flu (diff subtype then vacc. for)

83

influenza vaccine types

-killed/inactivated: trivalent (BAA) quad (BBAA)
double strength for oldies, prod. in eggs
-split virus (subvirion): for egg hypersn
-LAIV: intranasal (BA) approv. for 2-49 yo

84

if incubation period is less than time req for primary immune response (7-10d) then..

OUTBREAK
1st defense: anti-infective therapy
2nd: vaccination (so ppx can be stopped in about 14 d)
3rd: barrier

85

how to tx influenza preggos

if confirmed: Oseltamivir x5 (w/in 2 d onset)
if exposed: ppx Zanamivir or Oseltamivir x 10

86

Bacillus anthracis

G+ boxcar, spore forming, non-motile rod
aerobic, catalase +, encapsulated
gamma hemolysis
facultative IC pathogen of *MACROPHAGES*
(member of Bacillus cereus complex) B. cereus gen. non-encaps

87

B. anthracis potency

produces exotoxins: cause edema and death

88

anthrax common in US?

NO; disease of herbivores, humans dir. contact spores in soil, animals, an. prod
contact w/ sick/dying animals

89

3 types of anthrax

cutaneous
GI
pulm(inhal): spores in alv. spaces-->phago by macros-->migr. to mediastinal and peribronchial LNs where spores germinate-->lyse macro
veg. cells prod. exotoxins-->toxemia, hem. LM and massive septicemia (local and syst.)

90

length of anthrax course

(10d incubation)
fulminant 3-6 days!

91

anthrax prodrome: specific?

no: FEVER, myalgia, N/V
*no rhinitis or pharyngitis (unlike flu)
-->rapid prog. to alt. ment stat (conf/coma), seizures, resp distr, cyanosis (pulm. consol. may be absent)-->death

92

anthrax hallmark on CXR

WIDENING mediastinum and pleural effusions +/- pulmonary involvement
ACUTE onset (unlike influenza, TB, syst. mycoses)

93

other anthrax sp. s/s

raised HCT
diaphoresis

94

anthrax tx: abx?

YES: oral cipro, doxy for 60 DAYS

95

anthrax: vaccine?

YES: for ppx after potential exposure (3 dose)
LAV for animals
AVA (BioThrax): subunit purified Ag (induction of Ab to B. anthracis proteins: PA*, EF, LF)

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