Bacterial pneumonia Flashcards
Pseudomonas aeruginosa
Gram(-) rods
Strict aerobes
Nonfermenters
Oxidase(+)
Produces pyocyanin (exotoxin) & pyoverdin (siderophore)
Glycocalyx (slime layer) (anti-phagocytic)
Usually free-living environmental
Can be normal flora
Minimal growth requirements
Resistant to detergents & disinfectants
Extremely Ab resistant
What are the 7 virulance factors for P. aeruginosa
Endotoxin: cell wall component; when bloodborne causes sepsis
Exotoxins: can be released into tissue (ExoA, similar to diphtheria tox) or injected into host cells (type III secretion sys, ExoS, damages cytoskeleton)
Enzymes: elastase, protease: histotoxic, facilitate invasion of bloodstream, collapse alveoli and rupture blood vessels
Pyocyanin interferes with the terminal electron transfer system
Glycocalyx of alginate is antiphagocytic, biofilm glue
Efflux pumps: toss antibiotics back out of cytoplasm
What is the exotoxin released into tissue by P. aeruginosa
ExoA
What allows release of exotoxin released into tissue by P. aeruginosa
type III secretion sys,
ExoS, damages cytoskeleton
What virulance factor of P. aeruginosa antiphagocytic and acts as a biofilm glue
Glycocalyx of alginate
Which virulance factor of P. aeruginosa interferes with the terminal electron transfer system?
Pyocyanin
T/F Outer membrane of P. aeruginosa is is 10-100X less permeable to antibiotics than E. coli’s
true
What factors enable pseudomona aeruginosa to cause nosocomial (hospital induced) infections?
grows in water
highly resistant to antibiotics
hospital is filled with vulnerable patients (e.g. burns/cuts etc)
Where is psuedomona aeruginosa typically found?
Environmentally ubiquitous (water and plants)
What conditions does psuedomona aeruginosa cause?
pneumonia
osteocondritis
nosocomial UTIs
surgical site infections
brain abscess in cancer patients
Otitis externa / folliculitis
Endocarditis
Corneal infection
psuedomona aeruginosa is the most common Gram(-) isolate from what conditions?
corneal ulcerations and endocarditis
What the most commoncomminuty aquired psuedomona aeruginosa infections
Otitis externa / folliculitis - from unchlorinated hot tubs
Endocarditis - IV drug users
Osteochondritis - puncture wounds through sneaker soles (most common in children)
Corneal infection in contact lens wearers
What is the mortality rate for immunocompromised infected with psuedomona aeruginosa?
> 50%
What are the most common diseases caused by psuedomona aeruginosa in immunocompromised pts?
Pneumonia
Endocarditis
Meningitis
Ecthyma gangrenosum
What are most common causes of psuedomona aeruginosa infection in healthy hosts?
nosocomial UTI, Cystic fibrosis pneumonia, burns, local infections
What does a non-bacteremic pneumonia typically look like on chest x-ray?
diffuse bronchopneumonia (usually bilateral with distinctive nodular infiltrates with small areas of radiolucency) and pleural effusions
What does a bacteremic pneumonia typically look like on chest x-ray?
progresses rapidly,
(1) poorly-defined, hemorrhagic, often subpleural, nodular areas with a small central area of necrosis
(2) multiple, 2-mm to 15-mm, necrotic, umbilicated nodules with hemorrhagic parenchyma
Two cultures are ruitinely done for pneumonia (aerobic and non-aerobic) which will grow psuedomona aeruginosa?
aerobic
What are features that allow diagnosis of psuedomona aeruginosa?
Nonfermenting, oxidase(+)
Metallic sheen on triple-sugar-iron (TSI) agar
Green color on nutrient agar (pyocyanin)
Fruity aroma
For an uncomplicated psuedomona aeruginosa UTI what would you treat with?
ciprofloxacin
for all other psuedomona aeruginosa infections what treatment would you use?
IV anti-pseudomona penicillins
piperacillin/tazobactam
or
ticarcillin/clavulanate plus gentamicin or amikacin
What would be an indicator of pseudomona aeruginosa infection at a lesion site?
green color caused by pyocyanin virulance factor -
what are similarities and differences between pseudomona aeruginosa and Burkholderia cepacia
Both grow easily in IV fluid, irrigation solutions
Unlike P. aeruginosa, Burkholderia cepacia doesnt usually infect healthy patients, “colonizing” rather than “infecting”
What diseases does colonization of Burkholderia cepacia lead to infection in?
Cystic fibrosis pneumonia, pneumonia in other preexisting diseases with neutropenia, catheter-assoc UTIs, IV-assoc septicemia, wound infections, foot rot in swamp-deployed military
Burkholderia cepacia infection in CF, cancer, HIV should be treated with what?
trimethoprin-sulfamethoxazole
alternatives include third-generation cephalosporins, ciprofloxacin, ampicillin-sulbactam, chloramphenicol, or meropenem
T/F Experimental vaccines for Burkholderia cepacia are available to CF patients
true
Burkholderia pseudomallei causes what in primarily developing-nation veterinary cases?
melioidosis
What is transmission of Burkholderia pseudomallei?
Transmission by direct contact with contaminated water, soil
What is the structure gram stain of Burkholderia pseudomallei?
Motile Gram(-) rod
T/F Human-to-human transmission can rarely occur; standard precautions, mask on patient
true
T/F US has only few cases of Burkholderia pseudomallei per year and usually found in travelers, immigrants, IV drug users
true
What describes the appearance of B pseudomallei in culture?
Unusual “wrinkled” colony morphology
What are the initial symptoms of Burkholderia pseudomallei infection?
Initial Symptoms flulike (fever, sweats, rigors, headache) + muscle tightness, light sensitivity
pregression can range from acute local infection to septicemia with abscesses in all organs
Septicemia of B pseudomallei is associated with what course and symptoms?
Flushing Cyanosis Disseminated pustular eruption High fevers Rigor Bloody, purulent sputum
If untreated fatal ==> 7-10d
What are the risk factors for B pseudomallei infection?
diabetes,
renal dysfunction,
chronic pulmonary disease
B pseudomallei infection may resolve and then reactivate years later resembling what disease?
TB
B pseudomallei infection should be treated with what?
Ceftazidime alone
or in combination with either trimethoprim-sulfamethoxazole or amoxicillin clavulanate
True or false B pseudomallei infection is reportable infection to authorities because it is weaponizable
true
inform CDC and FBI as well as local health authorities
True or false Burkholderia cepacia infection has extreme antibiotic resistance
true
Where is B. mallei found?
Primarily developing-nation veterinary: Glanders
T/F melioidosis (B pseudomallei) and glanders (B. mallei) have been used as biowarfare agents: during WWI, used to infect Russian horses&donkeys
true
Transmission of B. mallei is through what?
from animals (zoonosis)
What is resevior for B. mallei?
Maintained in animal reservoirs, not soil or water
What is “Farcy”?
Milder B. mallei infection that establishes a chronic form
T/F B. mallei Septicemia: flushing, cyanosis, and a disseminated pustular eruption untreated fatal 7-10 days
true
treat B. mallei with
amoxicillin and clavulanate
doxycycline,
or trimethoprim and sulfamethoxazole
Chlamydophilia pneumoniae can be transmitted from human-to human – how?
Respiratory secretions
What transmits Chlamydophilia psittaci to humans ?
Infected birds - transmit via the respiratory route through direct contact or aerosolization. Quite rare, but serious.
What are the three clamydia pneumonia causing species?
C pneumoniae
C psittaci
C. trachomatis - infants from infected birth canal (CLAP)
What is the incubation period of C pneumoniae?
3-4 weeks
true/false C pneumoniae Infection is common, often asymptomatic, most symptoms relatively mild
true
When does fever present in course of disease with C pneumoniae?
first few days, often absent by the time of examination.
What clinical signs can be found in even mild course of infection with C pneumoniae?
What are other clinical signs?
Rhonchi and rales
Headache, sinus percussion tenderness
clamydia undergoes 2 form life cycle:
elementary bodies and reticulate bodies
What features describe C. trachomatis infection?
Nasal obstruction and discharge, cough, tachypnea, “inclusion conjunctivitis”, middle ear abnormality, Scattered crackles with good breath sounds
What is most common cause of pneuromnia from C. trachomatis
12,000 cases/yr in infants from infected mothers
Treat C. pneumonea with?
Doxycycline
Alternatives include erythromycin, azithromycin, and clarithromycin, Telithromycin
Treat C psittaci
Tetracycline or doxycycline
curable within 7-14 days
Treat C. trachomatis
infants with erythromycin
If prophylactic treatment of C. trachomatis treat with
oral erythromycin, not just eye ointment
prevents progression to pneumonia
Four Pseudomonas and Burkholderia pneumonia causing bacterial pathogens
P. aeruginosa
B. cepacia
B. pseudomallei
B. mallei rare in US but can be lethal
Have what common attributes?
Gram(-), strict aerobes, nonfermenters, Oxidase(+), grow easily in culture.
common&serious nosocomial pathogen
P. aeruginosa
common, serious in context of CF
B. cepacia (P. aeruginosa is also dangerous for CF)
Which species are rare in US?
B. cepacia
B. pseudomallei
B. mallei
B. pseudomallei and B. mallei rare in US but can be lethal
P. aeruginosa and B. cepacia have minimal growth requirements which allows what?
contaminate hospital solutions
what is biggest cause of anitbiotic resistance in bacterial pulminary infections caused by gram (-) bacteria?
All, but particularly P. aeruginosa, have extreme antibiotic resistance from combination of low-permeability outer membrane and efflux pumps
endocarditis in IV drug addicts, Otitis externa in underchlorinated hot tubs, Osteochondritis in sneaker punctures, corneal infections under contact lenses
Caused by what bacterial pneuomea causing species?
P. aeruginosa
Most common presentations for serious disease:
P. aeruginosa
B. cepacia
B. pseudomallei
B. mallei
P. aeruginosa in hospitals,
B. cepacia in CF centers,
B. pseudomallei in previously-ill travelers/immigrants or Vietnam veterans,
B. mallei in previously-ill travelers/immigrants with animal handling history.
All can present as septicemia/pneumonia with poor prognosis.
How would you diagnose?
P. aeruginosa
B. cepacia
B. pseudomallei
B. mallei
culture and Gram stain
Treat with latest combinations of antibiotics, test Ab sensitivity both before and during treatment
Clyamydia summary slide
Chlamydia is a small, obligate intracellular bacterium (so must use drugs that penetrate the human cell membrane).
Chlamydia replicate in a unique manner beginning with tiny, infectious, rugged, elementary bodies which “unpack” into reticulate bodies after infection.
Reticulate bodies form intracellular inclusions that are visible on microscopy; within the inclusions they multiply by binary fission, forming new reticulate bodies and later new elementary bodies.
Unusual life cycle complicates research; one known virulence factor is T3SS used for entry & establishing inclusion body.
C. trachomatis is the cause of several human diseases, particularly the common urogenital infection (safe sex practices!).
C. pneumoniae, C. psittaci, and C. trachomatis can all cause pneumonia.
Treatment can often be initiated based on physical findings, additional diagnostics are available and may be desired in various situations (tissue culture for C. trachomatis in rape victims; serology or MIF to differentiate pneumonias).
Treat with tetracyclines (doxycycline) EXCEPT for pregnant/pediatric/allergic patients, who get erythromycin or other alternatives. Patients who get alternatives may need follow-up testing and retreatment.
. What is problematic about P. aeruginosa as a nosocomial infection?
A Extreme antibiotic resistance
B Propensity to grow in low-nutrient aqueous solutions
C Ability to cause bacteremia
D All of the above
D: P aeruginosa is a formidable opponent for your hospital infection control
To which patient(s) is a B. cepacia infection dangerous despite treatment?
A A pediatric CF patient
B A geriatric cancer patient
C A previously-healthy woman undergoing urinary catheterization
D A and B not C
E All of the Above
A
Cystic Fibrosis is the most important predisposition for poor outcomes of cepacia infection.
