Lesson 11: Pseudomonas, Vibrio, Haemophilus Flashcards
It is an opportunistic pathogen that infects burns, wounds, surgical incisions, and sites of catheterization
Most common cause of infections of burn injuries and outer ear (otitis externa)
Pseudomonas aeruginosa
Is P. aeruginosa motile?
Yes, it is a flagellated bacterium with a polar flagellum, arranged in an amphitrichous manner
P. aeruginosa is non-capsulated but some strains posses a _________
slime layer
Is P. aeruginosa gram positive or negative?
Gram negative
2 commonly used media for the cultivation of P. aeruginosa
Nutrient Agar Medium
MacConkey Agar Medium
Optimum pH of P. aeruginosa
5.6 - 9.0 = can survive
6.6 - 7.6 = maximum growth
Some strains of P. aeruginosa show what type of hemolysis?
Beta hemolysis
P. aeruginosa is an obligate aerobe meaning?
It can only grow in the presence of oxygen
What media is used for P. aeruginosa when the growth of the bacterium occurs as “dense turbidity” in the broth medium with a “surface pellicle”?
Trypticase Soy Broth
Nutrient Broth
4 Types of Pigments of P. aeruginosa
Pyocyanin
Fluorescein
Pyorubicin
Pyomelanin
In Nutrient Agar Medium, Pseudomonas aeruginosa produces what type of odor?
Sweetish odor
Musty or Earthy smell
It is a selective medium for P. aeruginosa and other species of Pseudomonas which consists of “Cetrimide” that inhibits the growth of gram-positive bacteria and normal flora
Cetrimide Agar Medium
Vibrio cholera on Monsur’s Gelatin Taurocholate Trypticase Tellurite Agar Medium
24 hours incubation:
- small colonies
- 1-2 mm in size
- grayish color with black centers
48 hours of incubation:
- increase to 3-4mm in size
What is the expected color in Cetrimide Agar Medium if there is presence of P. aeruginosa?
Greenish-blue coloration
In MacConkey Agar Medium, P. aeruginosa shows what color since it is a non-lactose fermenter unlike E. coli and Klebsiella which are lactose fermenters?
None, since it is a non-lactose fermenter
Klebsiella and E. coli = Pink colony
He isolated “vibrions” from cholera patients because of their motility
Filippo Pacini
Identify the name of the Pigment
Bluish-Green
Pyocyanin
Identify the name of the Pigment
Greenish-Yellow
Fluorescein
Rigid, curved rods, or “Comma shaped” and are highly motile-single polar flagellum
Vibrio
Identify the name of the Pigment
Reddish-Brown
Pyorubicin
Identify the name of the Pigment
Brown to Black
Pyomelanin
It is the most important pigment from the diagnostic point of view since it is not produced by any other species of Pseudomonas but only by the Pseudomonas aeruginosa
Pyocyanin
It is characterized by sudden effortless vomiting, profuse rice water stool followed by rapid dehydration
Cholera
The motility of Vibrio cholerae is called as?
Darting motility (swarm of gnats)
Most medically important member of the genus Vibrio
Vibrio cholerae
Vibrio cholerae was first isolated by him from cholera patients in Egypt
Robert Koch
Growth of Vibrio cholerae is better on acidic or alkaline medium?
Alkaline medium (6.4 -9.6) (optimum 8.2)
Vibrio cholera on Gelatin Stab Culture
After 3 days of incubation, a “White Line” of growth appears
Selective Medium used for Vibrio cholera
Yellow colony
Sucrose fermentation
Readily visible against a dark green background of the agar
Thiosulphate citrate bile sucrose (TCBS) agar
An Enrichment Medium used for Vibrio cholera
Rapid growth: 6 hours
Formation of Thick Surface Pellicle
1mL stool/10mL alkaline peptone water
37C for 4-6 hours incubation
Alkaline Peptone Water (pH 8.5)
Vibrio cholera ferments what carbohydrates?
Glucose
Mannitol
Maltose
Mannose
Sucrose
True or False
Vibrio cholerae are non-halophilic
True, they cannot grow in media with more than 6% sodium chloride
Vibrio cholera on Nutrient Agar
Round
Moist
Translucent
“Bluish” colonies
1-2mm size
Vibrio cholera on Blood Agar
A zone of “green discoloration” and will become “clear”
Vibrio cholera on MacConkey Agar
Colorless colony, but will change to pink after a while
Vibrio cholera on Alkaline Bile Salt Agar
Similar colonies on Nutrient Agar Medium since it is just a modified version
Vibrio cholera does not ferment what carbohydrates?
Inositol
Arabinose
Lactose
True or False
Carbohydrate metabolism is fermentive, producing acid, but no gas
True
Vibrio cholera is:
Catalase and oxidase: positive
Nitrate Reduction: positive
Indole: positive
Methyl Red: Negative
Urease: Negative
True
What test is used to identify V. cholera colonies and performed when a loopful of growth is mixed with a drop of 0.5% sodium deoxycholate on a slide.
Mixture loses turbidity: mucoid and forms a “string” when loop is drawn away slowly = positive test
String Test
Route of Transmission of Vibrio cholera
Fecal-Oral route
Infectious dose of cholera in WATER
10^9
Infectious does of Cholera in FOOD
10^3
Incubation period of cholera
1 to 4 days
Assists the enterotoxin of vibrio cholera as it serves as a mucosal receptor for subunit B, which promotes entry of subunit A into the cell
Ganglioside GM1
Activation of this subunit of the enterotoxin of Vibrio cholera yields increased levels of intracellular cAMP and results in prolonged “hypersecretion” of water and electrolytes
Activation of subunit A1
This toxin of cholera binds to cell membrane via B sub-unit and this reverts back to allow A sub-unit to enter the cell membrane
Cholera Toxin
Cholera Enterotoxin
Choleragen
Habitat of Haemophilus
Upper Respiratory Tract of Humans (Nasopharynx of approximately 75% of healthy people)
Can H. influenza growth in a candle jar with 5% CO2?
Yes
This occurs when the colon cannot absorb the fluid fast enough. These factors contribute to decrease blood pressure.
Diarrhea
“Vibrio cholerae” colony color on TCBS (Thiosulfate Citrate Bile Salt Sucrose) Agar
Yellow
“Vibrio parahaemolyticus and Vibrio vulnificus” colony color on TCBS (Thiosulfate Citrate Bile Salt Sucrose) Agar
Green
Identify the bacteria:
Small
Pleomorphic
Gram-negative bacilli or coccobacilli with random arrangements
Found on mucous membrane of the URT
Haemophilus influenza
True or False
Encapsulated strains appear more mucoidal than non-encapsulated strains, which appear as smaller, compact grey colonies for H. influenza
True
True or False
H. influenza required hemin (X factor) and NAD (V factor) for growth
True
Standard Medium used for the growth of H. influenza
Chocolate Agar Plate (CAP)
prepared with: heat-lysed horse blood( a good source of hemin and NAD) ; can also use sheep blood
Characteristic of H. influenza on CAP
Large
Round
Smooth
Convex
“Colorless to grey”
Opaque
What is the smell of H. influenza on plates?
Pungent indole smell
What agar is used for H. influenza that shows a characteristic:
“Flat pinpoint” colony
Shows “satellitism” with S. aureus
Blood Agar
What type of hemolysis does H. influenza show on Horse Blood Agar?
Beta-hemolysis
What type of H. influenza colonizes the nasopharynx, and may penetrate the epithelium and capillary endothelium to cause “bacteremia”
Type b H. influenza
This type of H. influenza can cause meningitis, epiglottitis, bacteremia, and cellulitis
Type b H. influenza
This type of H. influenza can cause otitis media, sinusitis, tracheobronchitis, and pneumonia
Nontypable H. influenza
Haemophilus species that causes “pneumonia and endocarditis”
H. parainfluenza
Haemophilus species that causes “genital chancre”
H. ducreyi
Haemophilus species that causes “conjunctivitis or Brazilian purpuric fever”
H. aegyptius
