4-Lower Respir Infections Bacteria Flashcards
bronchitis bugs
bordetella pertussis
mycoplasma pneumoniae
acute bacterial bronchitis clinical
acute onset cough W/O fever, tachypnea, rales (pneumonia signs)
-usually viral
bordetella pertussis
fastidious so require complex media, specific environ
-adheres to ciliated respir mucosa
-restricted to humans (person to person spread) esp unvac or <1 yr
pertussis presentation stages
- incubation ~7-10 days
- catarrhal- fever, malaise, sneezing, anorexia ~1week
- paroxysmal- repetitive cough w whoops, cyanosis, vomit ~2 weeks
- convalescent- diminished paroxysmal cough, secondary comps ~3 weeks
bordetella pertussis virulence factors
- filamentous hemagglutinin to attach to ciliated cells
- pertussis toxin- AB toxin, inc cAMP to inc respir secretions = paroxysmal cough
pertussis dx
multiplex NAAT PCR test (specific and sens)
treat with antibiotics
prevent with DTaP vac
pneumonia symptoms
fever + cough + chest pain + dyspnea + sputum production (rust colored or purulent or foul or water)
in older pts maybe no fever but major complaint of mental status changes
tachycardia, tachypnea, hypoxemia, abnormal auscultations (crackles/rhonchi)
risk factors pneumonia
secondary to viral RTI
-heart dz, diabetes, lung dz, cancer, immunosup, cystic fibrosis
-age extremes
-smoking, alc, narcotics
pneumonia pathogenesis
enter small airways then grow in rich lung environ
-capsules, intracell growth, IgA protease, exotoxins LPS virulence factors
inflamm + acc fluid, neutrophils, fibrin = consolidation or infiltrate
-irreversible if caseous necrosis or cavitation
aspiration pneumonia
foreign material into bronchial tree
-saliva, food, nasal secretions carry bacteria
alcoholics, coma pts, stroke pts
secondary bacterial pneumonia after aspiration
lobar pneumonia
localized to only one lobe of lung
most gram neg bacteria
-strep pneumoniae
-staph aureus
-H. influenzae
bronchopneumonia
pus thru bronchi
-multi lobes or places not just one lobe
mycoplasma pneumoniae
chlamydophila pneumoniae
legionella pneumophila
typical pneumonia features
- sudden onset
- toxic facies
- productive cough
- purulent/bloody sputum
- fever
- inc neutrophils
- strep pneumoniae usually
lobar
atypical pneumonia
- gradual onset
- well appearing facies
- non productive cough
- scant watery sputum
- normal or elevated WBC not huge inc
- patchy infiltrate on Xray
- mycoplasma pneumoniae
community acquired pneumonia
not from healthcare setting
MDR gram neg less likely
hospital acquired pneumonia
hospitalized pts
-ventilator associated pneumonia
-MDR gram negatives more likely in VAP > HAP > CAP
pneumonia dx
not need testing for etiologic agent and no definitive ID of agent made
do culture, urine antigen test, gram stain, PCR
-pos blood culture = severe dz
CAP dx
made via clinical signs/symptoms with chest xray
-hard to disting b/t bacterial or viral
-antibiotics
-do CBC and blood culture
strep pneumoniae
normal colonizer of URT
-has capsule of polysacs so vaccines have polysacs from various serotypes
-IgA protease and polysac anti phagocytic virulence factors
classic pneumococcoal pneumonia presentation
-abrupt onset of cough, fever, chest pain, crackles, sputum (rust)
-poor oxygenation
should resolve in a week
S. pneumoniae lab dx
- PCR tests
- gram stain
- culture blood (bile sol, optochin sens)
- urine collection for pneumococcal polysac
S. pneumoniae treatment
antibiotics
vaccines:
23 valent and 13 valent (conjugate)
Staph aureus
normal microbiota
-catalase and coagulase pos (differentiate from other staph)
virulence factors: protein A for Fc portion of antibody, panton valentine leukocidin for pore forming cytotoxin, coagulase
MRSA
methicillin resistant Staph aureus
-resist all beta lactams but not more virulent just harder to treat
treat with linezolid (50S inhib) or vancomycin
gram neg causing pneumonia
- klebsiella pneumoniae (fac anaerobe)
- pseudomonas aeruginosa (aerobes)
more likely in HAP and secondary to aspiration pneu
part of normal microbiota
gram neg pneumonia features
- often have comordibities
- foul smelling sputum
- any lobe affected
- antibiotic resistance big problem
gram neg pneumonia dx
multiplex PCR test/sputum culture/gram stain, blood culture
treat with braod spectrum antibiotic cocktails
Klebsiella special features
-produce extended spectrum beta lactamases
-have mucoid colonies for capsule, very sticky
Kleb pneumonia clinical
present as classic lobar + bloody sputum ‘currant jelly’
treat with broad spectrum antib but inc rate of resistance
prevent by disinfecting environ and use sterile respir equipment
Kleb virulence factors
- LPS
- capsule
pseudomonas special features
-motile
-obligate aerobe
-blue/yellow/green pigments
-smells like grapes
-likes to grow in hand soaps, dilute antiseptics, water with no minimal nutrients
-forms biofilms
pseudo pneumonia risk factors
- burns
- immunosupp therapy
- ventilator use
- cystic fibrosis
pseudo virulence factors
- toxin A = cell death from ADP ribosylation of EF-2
- antiphagocytic capsule
- leukocidin
- phospholipace C
- blue pigments
cystic fibrosis
from pseudo
-convert non-mucoid to mucoid = sig affects pulmonary fxn
-almost impossible to eradicate bc biofilms and continued impairment
atypical pneumonia
aka bronchopneumonia
- walking - mycoplasma pneu, chlamydia pneumoniae
- toxic - legionella pneumophila
patchy pattern xrays
atypical pneumonia dx
-gradual onset of fever, headache, muscle ache, watery sputum
treat with empiric therapy based on CAP/HAP/VAP
mycoplasma pneumoniae special features
-no peptidoglycan, sterols instead
-look like fried egg
-restricted to humans
mycoplasma pneu virulence factor
-P1 adhesin binds to ciliated epi cell to damage = loss of escalator
cough > pneumonia
mycoplasma pneu clinical
-gradual onset bronchopneumonia
-anemia (IgM resp)
-patchy infiltrates
-self limiting to 2 weeks
mycoplasma pneu dx
-NAAT PCR
-NOT culture, cold aggultinin, or serology
treat with antibiotics but not beta lactams bc no peptidoglycan
-no prevention
chlamydia pneumoniae
atypical CAP but not clinically disting from other causes
-associated with atherosclerotic plaque form, refractory asthma, MS, rheumatoid arthritis
dx with multiplex NAAT
treat with antibiotics not beta lactam
legionella pneumophila
causes legionnaires dz and pontiac fever
-pontiac is self limiting, no person person spread, low mortality, no pneumonia, very mild
-legionnaires has underlying pulm dz, in late summer or autumn, must treat with antibiotics
legionella special features
-2 morphologies dep on location
-slow growing
-needs special agar with high humidity so ubiquitous in freshwater, intracellular pathogen esp amoeba
legionella spread
-where disinfectants are diluted out/improper disinfection
-cooling/humidifying systems old buildings, hotels, factories, hospitals, aerosols from manmade water supplies
legionella virulence
-attach to alveolar macrophages
-inject protein into host cell via type 4 secretion system to hijack (induces uptake, prevents fusion with lysosome, recruits organelles)
-lyse macrophage to release enzymes = inflamm, lung necrosis, systemic toxicity
legionella pneumophila clincal
-progressively worsening over 3-6 days
-rapid onset fever with fatigue
-chills, pleurisy, vomit, diarrhea, confusion, delirium
-high mortality esp HAI
legionella pneumophila dx
-exposure hx linked by location indicating outbreak
-patchy infiltrates on xray
-hyponeutremia (low sodium)
NAAT of sputum or lavage
legionella urine antigen test
mycobacteria categories
- M. tuberculosis complex
- non tuberculosis (NTM) > rapid or slow growing
- M. leprae and M. lepromatosis
mycobactera structure
-rods with lipid rich cell wall (waxy)
-acid fast staining (Ziehl Neelsen or Kinyoun)
-humans only reservoir but usually latent carriers
drugs for mycobacterium
- isoniazid- targets mycolic acid
- ethambutol- targets LAM
primary TB outcomes
- clearance
- latent
- active
latent TB features
-cannot spread to others, not infectious
-small viable inactive bacteria in body
-not feel sick
-pos TB skin test or IGRA
-normal chest xray
-sputum cultures neg
-not require isolation but strong consider treat
active TB features
-large amount of active bacteria
-may spread to others via aerosols
-feel sick and cough, weight loss, night sweat, fever
-pos TB skin test or IGRA
-normal or abnormal chest xray
-pos sputum cultures
-isolation and require treat
TB pathogenesis
-taken up by phagocytes then survives and recuits B/T/NK cells
-if macrophage migrates to hilar lymph node then granuloma to prevent spread (latent) or systemic spread
-if active TB then CMI cannot control Mtb
TB and CMI
most of pathology and dz from CMI resp bc inc activation = more necrotic lesions and inflamm, tissue damage
active TB symptoms
fatigue + unexpected weight loss + weakness + fever + night sweats + cough +2/3 weeks
-sputum range from scant to yellow/blood streaked
primary TB is asymptomatic
how latent TB gets active
granulomas fall apart and allow Mtb to move to other parts of lung
disseminated TB
AIDS or immunocomp/HIV
-granulomas in any body tissue
aka miliary or extrapulmonary TB
TB dx
-tuberculin skin test
-interferon gamma release assay IGRA
-chest radiograph
-med history important
-culture or NAAT test or microscopy for acid fast rods
AFB sputum smears
for acid fast bacterium using auramine-O to bind mycolic acid
-can confirm mycobacterial dz but not specific for Mtb
tuberculin skin test
intradermal injection of purified protein derivatives (PPDs) from Mtb envelope
-BCG vac people can test pos
measure wheel size
cannot rule out if neg
IFN-y release assay IGRA
IFN-y release by T cells in blood stim with Mtb antigen so good for BCG-vac people
cannot rule out if neg
drugs to treat TB
- isoniazid INH- inhib mycolic acid
- ethambutol EMB- disrupt arabinogalactan syn
- rifampin RIF- inhib RNA syn
- rifapentine RPT- inhib RNA syn
- pyrazinamide PZA-prevents vitamin B5
bad side effects so low compliance, need direct observation
treating latent TB
3-4 mo of daily or weekly drugs (1-2) to reduce chance of reactivation
treating active TB
DOT required + 6.5 months of daily 2-4 drugs
direct observation therapy
drug resistance TB
- multidrug resist TB = isoniazid and rifampicin
- extensive drug resist TB = MDR + any fluoroquinolone and 1+ second line inject drug
BCG vaccine
live attenuated or inactive M. bovis
-in endemic countries not in US tho
-limited efficacy after infancy
drawback is that skin tests pos
nontuberculous mycobacteria
atypical, environment
-usually immunocomp, elderly, lung comorbid
-M. avium or M. intracellulare = pulmonary active TB like
-M. kansasii = chronic granulomatous pulmonary dz
-distinguish from Mtb by culture
no latency or reactivation but treat similar to Mtb
