Flashcards in LRT infections Deck (95):
primary agent of viral croup (laryngotracheobronchitis)
hPIV (hum. parainfluenza v)
paramyxovirus, types: 1-->4, no grp. sp. Ag
Hamagglutinin and neuraminidase activity
causes of peds bronchitis and pneumonia
1. RSV 2. *PIV* 3. Adenovirus 4. hMPV
agents of viral croup
*PIV*, influenza A/B, RSV, hMPB, Ad, non-polio enteroviruses, measles
viral croup is the most common cause of what in 6mo to 6 yo children
croup presents with this..
in contrast to acute epiglottitis
SUBglottal edema vs. AE: SUPRAglottal edema
in croup..symptoms first manifest here, then migrate here
in URT 1st then larynx, trachea, bronchi
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
other croup clin. manifest:
major complications of croup
1. Secondary bac laryngotracheitis:
as recov. from viral croup; px w. high fever, toxicity, RD
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
viral croup tx
oral/IM dexamethasone (better than neb. budesonide) or racemic epinephrine (bronchodilate)
*NO VACCINE* for viral croup
this is the most common infection of LRT in infants & leading cause of hosp. in childhood...
and the #1 agent is..
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)
is COPD an infectious disease?
no (inflamm), but low #s may be present
reduction in FEV1:FVC
AE-CB or AE-COPD
acute exacerbation; frequently causes by viral/bacterial inf. disease
neonate acute inf. bronchiolitis (AIB) agents
Strep agalactiae, E. coli, Klebsiella pneumoniae, Ureaplasma urealyticum, and U. parvum, Chlamydia trachomatis
infants/young kids: inf. bronchiolitis (AIB) agents
RSV*, hMPV, influenza v*, PIV, Ad, HBoV, Rhinovirus, coronavirus
much less bac: B. pertussis, Mycoplasma pneumo, Chlamydia pneumo
sig. manifest. of AIB
NO PNEUMONIA: only scattered wheezing at lung base, but clear lung field
bronchitis and bronchiolitis: infectious diseases?
may or may not be
bronchitis common etiology: viral or bac?
viral more common: (RSV, influenza, etc)
bac: Mycoplasma pneumo, Chlamydia pneumo, Bordetella pertussis
URT s/s: ha, sore throat, coryza then LRT symps: cough (if prod: sloughing of tracheobronch. epi) +/- bronchospasms, SOB, etc
distinct bronchitis negatives
NO FEVER (typically, or low)
NO tachycardia, tachypnea
NO pneumonia: clear CXR, no rales, no egophony, *scattered wheezing @ base
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
AE-CB and AE-COPD bac pathogens:
NTHi**, Moraxella catarrhalis, Strep pneumo
AE-CB, AE-COPD: more commonly exacerbated by bacteria or virus?
bacteria! freq. a new strain
if virus: influenza*, RSV
other cause: allergies, immpath
how to dx AE-CB/COPD
bronchoscopy spec. collection: Cx, sens.
>10^3 CFU/mL of agent needs to be det.
no evidence that can prevent, complex decision
the most important agent of LRT infections in infants?
paramyxovirus, F and G surface glycoproteins
strain A* and B (A is the more virulent strain)
danger!: high attack rate (95%), no vaccine
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
RSV is #1 cause of these in infants
LRT diseases: bronchitis, bronchiolitis, pneumo
RSV bronchiolitis can lead to asthma
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
RSV affects adults as
reinfection: common cold, minor URT disease
RSV affects elderly w/
COPD/CB, immune comp. (organ transplant), LRT disease
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
type 1 hypersent. to viral AG (IgE) and rel. of mediators
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
RSV bronchiolitis CXR findings
inc. AP diameter
loose floppy diaphragm
RSV bronchiolitis: self-lim? tx?
is self-limited, but do tx
children: sev. rhinitis and pharyngitis (lim. bronchi)
adults: afebrile rhinitis, viral pharyngitis
elderly: ARDS-->viral pneumo
RSV bronchiolitis lab collections
nasopharyngeal sec, resp asp. w/ epi cells-->DFA/IF/ELISA
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`
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
hMPV (hum. Metapneumovirus)
causes dis. sim to RSV, but more mild
HBoV (hum. Boca virus)
family: Parvoviridae (B19)
causes both URT/LRT inf.
*pk incidence MARCH-MAY no inf. Aug-Sept.
-pertussis-like syndrome, diarrhea*
causes of whooping cough..
Bordetella pertussis ("pertussis")
*LATE SUMMER/EARLY FALL
high attack rate! affects infants*/y. kids
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
hallmark of pertussis
LYMPHOCYTOSIS (entrapment in vasc/lymph compartments): 12-20,000 per mm3
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
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
the most commonly rep. vaccine-prev. dx in kids
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
does pertussis vaccination/disease confer immunity?
YES: prolonged (7-20 yrs) but not permanent
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
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.
Pertussis stages: Convalescent
gradual, cough dec. (may continue 2-6 wks)
superimposed viral resp inf. can trigger recurrence
differences in adult pertussis
paroxysmal cough (>14d), NON-PRODUCTIVE, worse at night, PERIPH. LYMPHOCYTOSIS IS RARE
breakthrough pertussis infections in vaccinated children due to
high virulence of B. pertussis
complications of pertussis
secondary bac. pneumo (main cause of mort)
toxic enceph. or anoxia
substn. weight loss/sleeping problems
pertussis tx: abx?
YES, but only effective @ catarrhal stage
eryth, clarith, azithromycin or TMP-SMZ
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*
pertussis close contacts: vaccine or abx?
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)
minor change: point mutation for H or N genes, occurs in both A and B types
may cause epidemics
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
influenza deaths occur most in...
the young and the old (65)
and medically compromised
typ. circulate in swine but cause sporadic human infection
H1N1v, H3N2v*, H1N2v
*most do not result in human to human spread
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)
other influenza risk factors (besides age)
pulm/CV disease (COPD, CD, CHF), pregnancy, neurological, neumomuscular disorders (aspiration)
influenza comprimesse this imp. defense mech of RT
destruction of ciliated columnar resp. epi (esp. lg airways)
immunity in influenza
CMI (CTLs+ IFN prod)-->recovery
Humoral (IgA2 to HA and NA)-->protects against reinfection
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)
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
NO! will predispose pt to sec. bac pneumo!!
influenza complication in kids admin. ASA
Reye's syndrome : hepatitis, encephalopathy
DO NOT give ASA to tx
influenza virus A or B, VZV
(use acetaminophen instead)
other complications of influenza
CNS (enceph.) or PNS (Guillain-Barre's)
cerebrovascular, cardiac, OM*, sinusitis
influenza lab dx
EIA/DFA, Cx, Hemagglutination inhibition
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)
no longer recommended antivirals for influenza
Amantadine, Rimantadine (against A, block m2 protein)
influenza antivirals against which types?
A and B (7yo, ppx>5 yrs
(less resistance to Zanamivir)
Oseltamivir (Tamiflu): tx/ppx >1yo
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)
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
if incubation period is less than time req for primary immune response (7-10d) then..
1st defense: anti-infective therapy
2nd: vaccination (so ppx can be stopped in about 14 d)
how to tx influenza preggos
if confirmed: Oseltamivir x5 (w/in 2 d onset)
if exposed: ppx Zanamivir or Oseltamivir x 10
G+ boxcar, spore forming, non-motile rod
aerobic, catalase +, encapsulated
facultative IC pathogen of *MACROPHAGES*
(member of Bacillus cereus complex) B. cereus gen. non-encaps
B. anthracis potency
produces exotoxins: cause edema and death
anthrax common in US?
NO; disease of herbivores, humans dir. contact spores in soil, animals, an. prod
contact w/ sick/dying animals
3 types of anthrax
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.)
length of anthrax course
fulminant 3-6 days!
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
anthrax hallmark on CXR
WIDENING mediastinum and pleural effusions +/- pulmonary involvement
ACUTE onset (unlike influenza, TB, syst. mycoses)
other anthrax sp. s/s
anthrax tx: abx?
YES: oral cipro, doxy for 60 DAYS