Curved Gram Negative Flashcards
How could you identify a colony of Pseudomonas?
Gram stain?
Oxygen requirement?
Motile?
Oxidase?
Capsule?
MacConkey agar?
Other distinguishing characteristics?
Naturally occurring location?
General infection locations?
- Gram stain?
- pigmented gram negative slightly curved rod
- Oxygen requirement?
- obligate aerobe
- Motile?
- yes, mobile
- flagella clustered at one end of the rod
- Oxidase?
- oxidase positive
- Capsule?
- Yes, some are mucoid
- capsules lost in repeated lab cultures
- Yes, some are mucoid
- lactose non-fermenting growth on MacConkey agar
- Grape-like odor & green color on nutrient agar
- Naturally occurring location
- not part of normal human microbiome
- soil, vegetation, moist hospital locations
- URT & GIT in hospital patients (patient to patient spread)
What are the major virulence factors of P. aeruginosa?
The great number of toxins
unusual for gram negative bacteria
What baceria is the leading colonizer in patients with cystic fibrosis?
P. aeruginosa
mucus stasis & accumulation
In vivo, makes no pili/flagella & reduces virulence
attenuate host immunity = slow lung injury
What bacteria is a major cause of ventilation assisted pneumonia; causing symptoms of fever, chills, purulent sputum
tracheobronchitis to necrotizing brochopneumonia
P. aeruginosa
What group of individuals most commonly become infected with P. aerugionsa bacteremia?
What other pathology does this cause?
Immuno-compromised individuals (high mortality)
- may cause ecthyma gangrenosum
- mostly in neutropenic and AIDS patients
- small or large painful maculopapular lesions
- Pink–> purple–> black and necrotic
What disease is characterized by the symptoms shown in the image provided? The patient had been in a Jacuzzi.
Pseudomonas folliculitis
frequently after immersion in water
What disease is characterized by the image provided? The patients is a frequent contact user.
acute irritation, corneal perforation, vision loss
Corneal ulcer under soft contact lens
P. aeruginosa- Eye infection
Infection after trauma to cornea (abrasion from contact lens)
What diseas is characterized by the image provided? Patient was recently in a pool.
mild irritation of external ear to desrruction of cranial bones
itching, pain (may be sever), mucopurulent exudate
Otitis externa (swimmer’s ear)
can be malignant in diabetic and elderly patients
What is unique about the endocarditis caused by P. aeruginosa?
What are the other 3 diseases that can be caused by P. aeruginosa?
tricuspid valve
Osteomyelitis, arthritis
UTI for patients w/ long-term indwelling urinary catheter
How would you identify a infection caused by Vibrio cholerae?
gram stain?
motility?
growth on what agar?
oxidase test?
growth requirement
capsulated?
genetic material?
- gram stain?
- curved, gram negative bacilli
- motility?
- darting motility (polar flagella)
- growth on what agar?
- TCBS agar (thiosulfate citrate bile-salt sucrose
- yellow
- oxidase test?
- oxidase positive
- growth requirement
- non-fastidious
- can grow in a wide temperature range
- capsulated?
- virulent strains are non-capsulated
- 2 circular chromosomes (one lager & one smaller)
Which two serotypes of V. chlerae produce cholera?
Where is it acquired from?
- serotypes O1 and O139 produce cholera toxin
- acquired from water contaminated with human feces
- acid sensitive
Major virulence factors of V. cholerae?
- Toxin (bacteriophage encoded) and toxin co-regulated pilus
- Toxin regulated pilus
- mediates adherence to intestinal mucosal
- site to where bacteriphage binds
- Toxin regulated pilus
- Colonization factors
- tcp & cep encoded proteins allow binding to mucosal cells
- bacteria don’t wash out with diarrhea
- tcp & cep encoded proteins allow binding to mucosal cells
- Toxins
- Zonnula occludens toxin: incrases intestinal permeability
- Accessory cholera enterotoxin: increases fluid secretion
- Neuraminidase: increase GM1 bindign sites for cholera toxin
- ALL strains produce LPS (O1 & O139 produce cholera toxin)
- Cholera toxin: AB5 , binds to ganglioside, who complex endocytosed, (follows opposite route of protein excretion)
- adenalate cyclase activated == incrases cAMP, turns on PKA CFTR phosphorylated and turned on, starts leaking chloride and sodium into the lumen, which causes passive diffusion of water into the lumen = diarrhea
- O1 can cause cholera even in absence of cholera toxin
What disease is characterized by the following symptoms?
1-3 day incubation, severe diarrhea, no fever
metabolic acidosis, hypokalemia, hypovolmeic shock
muscle cramps
rice water stool (flecks mucus)
What is the bacterial cause?
Cholera
C. cholerae
Milder diarrhea by toxin negative = gastroenteritis
How could you identify an infection caused by Vibrio parahaemolyticus?
Gram stain?
Growth requirement?
How is it acquired?
What agar would you grow it on?
- Gram stain?
- gram negative curved bacilli
- Growth requirement?
- facultative
- non-fastidious
- requires salt
- How is it acquired?
- eating contaminated seafood
- TCBS agar
- dark blue-green colonies b/c not fermenting sucrose
What diseases are caused by V. parahaemolyticus?
What are its important virulence factors?
- GI infection
- self-limiting diarrhea to mild cholera-like
- no blood or mucus
- Virulence
- thermostable direcy hemolysin (TDH)
- increases Cl- secreation by raising Ca++ in epithelial cells
- Produces dark blue-green colonies on TCBS agar
How could you identify an infection caused by Vibrio viulnificus?
gram stain?
motility?
oxidase?
growth on what agar?
growth requirement?
How is it acquired?
- gram stain?
- curved, gram negative bacilli
- motility?
- darting motility (polar flagella)
- oxidase?
- oxidase positive
- growth on what agar?
- TCBS agar (thiosulfate citrate bile-salt sucrose)
- green
- growth requirement?
- facultative
- non-fastidious
- halophilic (saltloving)
- How is it acquired?
- contaminated food or wound exposed to seawater
What diseases are caused by Vibrio vulnificus?
What are its important virulence factors?
- Syndromes (considered a flesh-eating bacteria)
- pre-existing wound contaminated
- rapidly occuring cellulitis– in healthy and debilitated
- wound edema, erythema, necrosis, –> septicemia
- Consumption of raw shellfish
- rapid onset septicemia followed by cutaneous lesiosn
- in elderly alcoholic men w/ liver abnormalities (more free iron available)
- Rare acute diarrhea after shellfish consumption
- pre-existing wound contaminated
- Virulence factors
- Vapsule, cytolysins, collagenase, protease, siderophores
- organism enhances virulence in the presence of optimum iron
How could you identify an infection caused by Gardnerella vaginalis?
gram stain?
how is it acquired?
What other distinguishign characteristics?
- gram stain?
- gram variable but appread gram-negative b/c LPS
- clusters
- how is it acquired?
- probabl STD
- Epithelial cells with clusters of gram negative rods
- “clue cells” in vaginal secretions
How could you identify an infection caused by Campylobacter?
gram stain?
growth preference?
motility?
- gram stain?
- small, gram negative S-shaped rods (filterable through 0.45 micrometers) ** ask micro to look for it specifically
- LOS (not LPS)
- motility?
- yes, motile
- growth preference?
- low oxygen (5-7%), increased CO2 (5-10%) at 42 degrees celcius
- slow growth
- Caampy-BAP (inhibit growth bowel flora)
- Skirrow’s medium (vancomycin, polymyxin B, trimethoprim)
- Blood free medium (CSM)
- need serine, proline, aspartate, glutamate in medium
Describe the virulence of C. jejuni?
Adhesins, cytolysins, entertoxins important for virulence
C. jejuni is engulfed by monocytes, intestinal epithelial & M cells
this induces cell death, bowel ulceration & inflammation
PMNs, monocytes & eosinophils infiltrate lamina propria
How would you identify a sample of Helicobacter pylori?
gram stain?
growth requirement?
urease test?
other specific tests?
typical colonization location?
How is its spread?
- gram stain?
- gram negative spiral rods 4-6 polar flagella
- Warthin-Starry silver stain
- Growth requirement
- moist microaerophilic conditions
- urease test?
- positive (increase pH)
- Urea breath test
- fasting patient drink solution 13C/14C-urea
- air breathed out will have detectable radioactive CO2
- Serology sensitive & inexpensive
- typical colonization location?
- interface gastric epithelium & overlying mucous layer
- Spread by close personal contact (fecal-oral & oral-oral)
- infection lasts for life (unless treated with antibiotics)
Important virulence factors for H. pylori
urease (neutralizes stomach pH)
flagella, proteins that reduce acid production
factors secreted into stomach epithelial, causes necosis of cells
