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MSII Micro Unit 4 > Bacterial Pneumonia 1 > Flashcards

Bacterial Pneumonia 1 Flashcards

1
Q

Pseudomonads

A
  • P aeruginosa
  • B cepacia
  • B pseudomallei
  • B mallei
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2
Q

P. aeruginosa bacteriology

A
  • gram neg rod
  • strict aerobe
  • non-fermenters
  • oxidase positive
  • produces pyocyanin (exotoxin) and pyoverdin (siderophore)
  • glycocalyx (anti-phagocytic slime layer)
  • usually free living environmental
  • can be normal flora
  • minimal growth requirements
  • resistent to detergens and disinfectants
  • extremely antibiotic resistance
  • motile
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3
Q

P. aeruginosa pathogenesis

A
  • fairly common saprophyte; opportunistic pathogen
  • ability to grow in water, plus its antibiotic resistance, plus vulnerable patients make it a nosocomial pathogen
  • grows easily in IV fluid and irrigation solutions
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4
Q

vulnerable patients to P. aeruginosa?

A
  • extensive burns
  • chronic respiratory disease (CF)
  • immunosuppression
  • long term catheterization, IVs
  • neonates
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5
Q

impact of P. aeruginosa

A
  • causes 10% of all nosocomial infections
  • # 2 cause of nosocomial pneumonia
  • # 1 for ICU pneumonia
  • # 1 cause of osteocondritis
  • # 2 cause of nosocomial UTIs
  • # 4 cause of surgical site infections
  • most common gram neg isolate from corneal ulcerations and endocarditis
  • second most common cause of brain abscess in cancer patients
  • sneaker puncture!
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6
Q

community acquired pathogenesis of P. aeruginosa

A
  • endocarditis in IV drug users
  • otitis externa/folliculitis in underchlorinated hot tubs
  • osteochondritis in puncture wounds through sneaker souls, most common in kids
  • corneal infection in contact lens wearers
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7
Q

virulence factors of P. aeruginosa

A
  • endotoxin- cell wall component, causes sepsis (like LPS)
  • exotoxin- can be released into tissue (ExoA) or injected into cells via a T3SS, damages cytoskeleton
  • enzymes- elastase, protease, facilitate invasion of blood
  • pyocyanin- interferes with terminal electron transfer system and gives green color
  • glycocalyx is anti-phagocytic
  • efflux pumps toss antibiotic out of cytoplasm
  • outer membrane is 10-100x less permeable to antibiotics than e coli
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8
Q

P. aeruginosa dx on exam

A
  • can infect anywhere, but predominantly nosocomial UTI, CF pneumonia, burns
  • local infections in previously healthy hosts
  • if immunocompromised or neonate, can progress to sepsis, with >50% mortality
  • pneumonia, endocarditis, meningitis
  • ecthyma gangrenosum- patch of infected skin, came from the inside out
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9
Q

non bacteremic CXR of P. aeruginosa

A
  • pneumonia resembles S aureus
  • diffuse bronchopneumonia
  • usually bilateral with distinctive nodular infiltrates with small areas of radiolucency and pleural effusions
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10
Q

bacteremic CXR of P. aeruginosa

A
  • progresses rapidly
  • poorly defined, hemorrhagic, often subpleural nodular areas with small central area of necrosis
  • multiple 2-15 mm necrotic, umbilicated nodules with hemorrhagic parenchyma
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11
Q

P. aeruginosa dx on lab

A
  • 2 sets of culture- aerobic and anaerobic (anaerobic will fail)
  • culture from relevant fluids- sputum, biopsy/aspirate joints, CSF for CNS, blood for sepsis
  • nonfermenting, oxidase positive
  • metallic sheen on triple-sugar-iron agar
  • green on nutrient agar
  • fruity aroma
  • biochemical tests available
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12
Q

P. aeruginosa trt

A
  • remove/change catheters/ IVs
  • being antibiotics without delay
  • antibiotic sensitivity testing
  • continue testing during treatment, resistance can develop
  • for uncomplicated UTI- ciprofloxacin
  • everything else:
  • antipseudomonal penicillin: piperacillin/tazobactam or ticarcillin/clavulanate plus gentamicin or amikacin
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13
Q

prevention of P. aeruginosa

A
  • keep neutrophils up
  • remove/ change catheters and IVs
  • burn unit precautions
  • handwashing
  • experimental vaccines for CF patients
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14
Q

B cepacia bacteriology and pathogenesis

A
  • grows easily in IV fluid, irrigation solutions
  • very limited ability to infect otherwise healthy patients
  • may be considered colonizing rather than infecting
  • CF pneumonia, pneumonia in other pre-existing diseases with neutropenia, catheter associated UTIs
  • IV associated septicemia
  • wound infectoins
  • foot rot in swamp deployed military
  • doesn’t have virulence factors like p aeruginosa
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15
Q

B cepacia and CF

A
  • CF/ cepacia pneumonia experience has become more common as pts with CF live longer
  • cepacia pneumonia in CF centers forms outbreaks
  • cepacia syndrome- accelerated pulmonary course with rapidly fatal bacteremia
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16
Q

B cepacia dx and trt

A
  • no pyocyanin
  • no treatment if healthy pt
  • if CF, cancer, HIV- treat with trimethoprin-sulfamethoxazole
  • alternates: 3rd gen cephalosporins, cipro, ampicillin-sulbactam, chloramphenicol, merpenem
  • experimental vaccines for CF patients
17
Q

B pseudomallei bacteriology

A
  • primarily developing nation veterinary: meliodiosis
  • transmission by direct contact with contaminated water/ soil
  • motile gram neg rod
  • human to human transmission rare, standard precautions, mask on pt
  • US has a few cases per eyar- travelers, immigrants, IV drug users
18
Q

B pseudomallei pathogenesis

A
  • initial symptoms flu like (fever, sweats, rigors, headache) and muscle tightness, light sensitivity
  • range of severity, acute local to septicemia with abscesses in all organs
  • septicemia sx:
  • flushing, cyanosis, disseminated pustular eruption, high fever, rigor, bloody/purulent sputum
  • if untreated, septicemia fatal in 7-10 days
  • risk factors: diabetes, renal dysfunction, chronic pulm disease
  • milder infections may resolve and then reactivate years later, reactivation resembles TB
  • reactivation seen in Vietnam vets
19
Q

B pseudomallei dx

A
  • patient history, culture and gram stain from blood, urine, skin lesions
  • PCR and immunoassays exist
  • imaging studies may be helpful- abnormal CXR plus multiple small abscesses in liver and spleen on ultrasound
20
Q

B pseudomallei treatment

A
  • several weeks of ceftazidime alone or with either trimethoprim-sulfamethoxazole or amoicillin-clavulanate
  • reportable
21
Q

B mallei

A
  • primarily developing nation veterinary: Glanders
  • bacterium is non-motile
  • both melioidosis and glanders have been used as biowarfare agents
  • WWI- used to infect Russian horses and donkeys
  • both could theoretically be used against humans in aerosolized formed
  • rare zoonosis, it is assumed that infected discharge passes through broken skin
  • maintained in animal reservoirs, not in soil or water
  • cleared from US livestock in 1945
  • therefore patients are from abroad or have smuggled animals
22
Q

B mallei pathogenesis

A
  • human to human rare, standard precautions, mask on pt
  • symptoms flu-like- fever, sweats, rigors, headaches
  • severity varies:
  • acute localized- nodule at infection site
  • acute pulmonary- bronchitis–> pneumonia
  • acute septicemic- fulminant, multiorgan involvement- flushing, cyanosis, disseminated pustular eruption, fatal if not treated in 7-10 days
  • milder infection may establish a chronic form called farcy
23
Q

B mallei dx

A
  • patient history
  • culture and gram stain from blood, urine, skin lesions
  • PCR and immunoassays exist
24
Q

B mallei trt

A
  • long term antibiotic trt with amoxicillin and clavulanate, doxy, or trimethoprim-sulfamethoxazole
  • reportable
  • if no evidence or animal occupational exposure, inform CDC and FBI as well as local health authorities
25
Q

chlamydia pneumoniae

A
  • respiratory secretions transmit from human to human

- 3-10% of community acquired pneumonia

26
Q

chlamydia psittaci

A
  • infected birds transmit to humans via respiratory route through direct contact or aersolizatoin
  • quite rare, but serious
27
Q

chlamydia trachomatis

A
  • transmitted when infant passes through infected birth canal
  • conjunctivitis and pneumonia
28
Q

C pneumoniae history and presentation

A
  • incubation 3-4 weeks
  • infection common, often asymptomatic, most sx relatively mild
  • fever is more often present in the first few days, often gone by time of examination
  • rhonchi and rales present even in mild disease
  • headache, sinus percussion tenderness
  • symptoms may be prolonged
  • pear shaped elementary bodies
29
Q

C psittaci history and presentation

A
  • exposure to birds, especially sick birds
  • incubation is 5-14 days or longer, abrupt onset
  • severity ranges from asymptomatic to severe pneumonia
  • non-productive cough, chest pain, splenomeg
  • fever is most common symptom and may reach 103-105
  • horder spots- erythematous, blanching, maculopapular rash; not universal
  • severe cases may progress to meningitis, encephalitis, endocarditis
30
Q

C trachomatis history and presentation

A
  • 12,000 cases/ year from infected moms
  • nasal obstruction and discharge
  • cough, tachypnea
  • conjunctivitis
  • middle ear abnormality
  • scattered crackles with good breath sounds
  • most patients are afebrile and only moderately ill
  • may also present in severely immunocompromised adult
31
Q

C pneumoniae dx and trt

A
  • microimmunofluorescence antibody tests, serology
  • cell culture impractical
  • CXR- single subsegmental infiltrate mainly in lower lobes
  • treat with doxy, alt erythromycin, azithromycin, clarithromycin, telithromycin
  • most cases are mild and respond to trt in outpatient setting
32
Q

C psittaci dx and trt

A
  • complement fixing or MIF antibody tests, serology
  • cell culture is hazardous
  • CXR- consolidation in a single lower lobe
  • trt with tetra or doxy
  • usually curable in 7-14 days
33
Q

C trachomatis dx and trt

A
  • culture or hybridization like genital chlamydia
  • CXR- bilateral interstitial infiltrates with hyperinflation
  • treat infants with erythromycin. if prophylactic, use oral and eye ointment
  • most pts are moderately ill and respond to appropriate antibiotics
  • course is protracted if untreated

MSII Micro Unit 4 (6 decks)

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