Bacterial Pneumonia 1 Flashcards
1
Q
Pseudomonads
A
- P aeruginosa
- B cepacia
- B pseudomallei
- B mallei
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
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
4
Q
vulnerable patients to P. aeruginosa?
A
- extensive burns
- chronic respiratory disease (CF)
- immunosuppression
- long term catheterization, IVs
- neonates
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!
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
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
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
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
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
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
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
13
Q
prevention of P. aeruginosa
A
- keep neutrophils up
- remove/ change catheters and IVs
- burn unit precautions
- handwashing
- experimental vaccines for CF patients
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
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
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
chlamydia pneumoniae
- respiratory secretions transmit from human to human
| - 3-10% of community acquired pneumonia
26
chlamydia psittaci
- infected birds transmit to humans via respiratory route through direct contact or aersolizatoin
- quite rare, but serious
27
chlamydia trachomatis
- transmitted when infant passes through infected birth canal
- conjunctivitis and pneumonia
28
C pneumoniae history and presentation
- 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
C psittaci history and presentation
- 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
C trachomatis history and presentation
- 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
C pneumoniae dx and trt
- 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
C psittaci dx and trt
- 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
C trachomatis dx and trt
- 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
