Pseudomonas and Non-Fermenters Flashcards
What are the general characteristics of Pseudomonas and other Non-fermenters?
- Gram-negative, non-spore forming bacteria, may be rods, or coccobacilli
- Obligateaerobes
- Good growth usually seen in 24h
- Glucose not fermented
What is the reservoir of Pseudomonas and NFs?
Soil and water in the environment.
What are the characteristics of P. aeruginosa?
- Aerobic Gram negative rod
- Motile with polar flagella
- Mucoid polysaccharide slime layer
- Pili on cell surface
What is the reservoir of P. aeruginosa?
Grows in unsterile water, medications, disinfectants
What are the main patients that are susceptible to P. aeruginosa?
- Burn patients
- Cystic fibrosis patients
- Patients with hematologic malignancies
- Immunocompromised patients
What are some of the main P. aeruginosa infections?
Pulmonary
“Swimmer’s Ear”
Bacteremia with ecthyma gangrenosum
What are the main P. aeruginosa virulence factors?
Exotoxin A
Exoenzyme S
Elastase
What is the function of Exotoxin A?
Blocks protein synthesis much like diphtheria toxin
What is the function of Exoenzyme S?
ADP-ribosylating toxin
What is the function of elastase?
Results in tissue destruction and hemorrhagic lesions via the degradation of elastin
How is P. aeruginosa identified?
- Glucose Non-Fermenter
- Oxidase positive
- Grape-like odor
- Produces Pyocyanin
What is the only bacteria that produces pyocyanin?
P. aeruginosa
What antibiotics are used against P. aeruginosa?
Resistant to many antibiotics due to changes in porins.
Combination therapy of cell wall active agent + aminoglycoside for serious systemic infections.
A gram‐negative rod grows as a colorless colony on a MacConkey agar plate. Further laboratory testing shows the organism is oxidase positive, does not ferment glucose, produces a sweet grape‐like odor and grows at 420C. Which of the following clinical infections is most likely to be caused by this organism?
A. Ear infection after swimming in a fresh water lake
B. Melioidosis
C. Community acquired urinary tract infection
D. Community acquired pneumoniae
E. Gastroenteritis following ingestion of
contaminated water
A. Ear infection after swimming in a fresh water lake
What is the associative odor with P. aeruginosa?
Grape-like odor
What is the reservoir of Buckholderia pseudomallei?
Soil, water, vegetation of S.E. Asia, 20˚ north and south of equator. Primarily found in India, Thailand, Vietnam, northern Australia. Also endemic in China, Taiwan, Laos.
What disease is caused by B. pseudomallei?
Melioidosis
What are the 3 possible manifestations of B pseudomallei infection?
- Acute Disease: septicemia with metastatic lesions. 95% mortality if untreated
- Subacute Disease: most common. TB like pneumonia with cellulitis and lymphangitis
- Chronic Disease: localized chronic cellulitis. Treat with antibiotics before draining otherwise become bacteremic
What is the reservoir of B. cepacia?
Recovered from water sources, wet surfaces,
detergent solutions
What diseases does B cepacia cause?
Opportunistic infectious agent that mainly causes respiratory infections
What is B. cepacia mainly problematic in?
Cystic Fibrosis patients
Why is B. cepacia especially problematic in CF patients?
It will cause more dry sticky mucus which is a good breeding ground as well as have increased inflammation of the airway
What is the mutation in CF?
There is a mutation in the CFTR gene which causes innate immunity and decreased NO level that will lead to increased airway inflammation and increased mucus. It also causes a failure to internalize bacteria.
What are the CF pathogens of chronic lung disease?
– S. aureus
– P. aeruginosa
– B. cepacia complex
What are the characteristics of B. cepacia?
- Glucose non-fermenter
- May be yellow pigmented
- Slow oxidase-positive
- Resistant to most antibiotics
What is the reservoir of Stenotrophomonas maltophilia?
– Soil, water, animals, vegetation, crops
– Not part of normal skin or gastrointestinal flora but can be recovered from almost any clinical site
What is the most common infection caused by S. maltophilia?
Respiratory tract
What is the 2nd leading cause of gram-negative nonfermentative bacillary infections?
S. maltophila. The most common is E. coli.
Is S. maltophilia oxidase positive or negative?
Oxidase negative
What is the main reservoir of Elizabethkingia meningoseptica?
Soil, water, plants, food-stuffs
May exist in water systems and wet surfaces in hospital environment with breast pumps as a common contaminated agent
What is E. meningoseptica associated with in infants?
Meningitis
What are the characteristics of E. meningoseptica?
- Oxidase Positive
- Pale yellow pigment on BAP
- Poor growth on MacConkey
What is the reservoir of Acinetobacter baumannii?
Free living in water and soil
Isolated foods, hospital air, inanimate objects,
numerous human sources
What are the characteristics of A. baumannii?
– Coccobacilli on Gram stain
– Good growth on BAP and MacConkey
– Oxidase negative
– Non-motile
A gram-negative rod was recovered from the CSF of a newborn with meningitis. It was an oxidase-positive, glucose non-fermenting rod, that failed to grow on MacConkey agar and was indole-positive. An epidemiologic investigation revealed that the mother was using a breast pump that belong to the hospital nursery and may have been the source of the causative agent. What is the likely agent of meningitis in this case.
A. Elizabethkingia meningoseptica B. Citrobacter koseri C. E. coli D. Listeria monocytogenes E. Neisseria meningitidis
A. Elizabethkingia meningoseptica
Main Infection P. aeruginosa
Skin/Lungs
Main Infection S. maltophilia
Pneumonia and UTI
Main Infection B. pseudomallei
Meliodosis
Main Infection B. cepacia
Respiratory tract infections especially for CF patients
Main Infection E. meningoseptica
Neonatal meningitis
Main Infection A. baumanii
Nosocomial infection
