28 Questions
What is the optimal growth temperature for Bacteroides fragilis?
37°C
What is the pH range for optimal growth of Bacteroides fragilis?
5-7
What structures does B. fragilis use for adhesion to other molecular structures?
Peritrichous fimbriae
What type of bacterium is Bacteroides fragilis?
Gram-negative
What type of metabolism does Bacteroides fragilis have in the gut microbiome?
Aerotolerant, anaerobic chemoorganotroph
How does B. fragilis survive the volatile intestinal micro-environment?
By utilizing outer membrane vesicles
What is the role of cytochrome bd oxidase in B. fragilis?
It is essential for oxygen consumption and can allow other obligate anaerobes to survive in the oxygen-reduced microenvironment.
What does the environmental-sensory system of B. fragilis effectively handle?
Bacteriocins secretion and resistance, bile salt resistance, and oxidative stress response
What is the main attributed factor for the high resistance to antibiotics of B.fragilis?
Genetic plasticity
What is a characteristic feature of the antibiotic resistance mechanisms in members of the genus Bacteroides?
High resistance rates amongst anaerobic bacteria
Which organism is the most prevalent in the B. fragilis group?
B. fragilis
What do animals lacking gut bacteria require to maintain body mass?
30% more caloric intake
What do Bacteroides species accumulate in their gastrointestinal tract?
A variety of antibiotic/antimicrobial resistance genes
Which enzymes are utilized by B. fragilis to resist the degrading effects of bile salts?
Bile salt hydrolase
What permits growth in the presence of nanomolar concentrations of O2?
Catalase, superoxide dismutase, & alkyl hydroperoxide reductase
What permits B. fragilis to survive/adapt in the ever-changing human gut microbiome?
The complex environmental-sensory system
What is the cofactor required for Haemophilus species growth, known as the V factor?
NAD+
Which agar is an excellent growth medium for Haemophilus due to increased accessibility to the required factors?
Chocolate agar
In the 'Staph streak' technique for culturing Haemophilus, what produces the necessary blood factor byproducts required for Haemophilus growth?
Staphylococcus colonies
Which species is an exception to the requirement of X and V factors and can grow well on both blood and chocolate agars?
Haemophilus haemoglobinophilus
What is the main attribute of the 'V factor' for Haemophilus species growth?
Nicotinamide adenine dinucleotide
What is the primary function of the 'Staph streak' technique in culturing Haemophilus organisms?
To enhance Haemophilus growth
What do most species of the genus Haemophilus require for growth on blood agar plates?
Both hemin and nicotinamide adenine dinucleotide
What prevents the growth of many Haemophilus species on blood agar plates?
Absence of X-factor bound to the blood cells
Why are Haemophilus bacteria categorized as pleomorphic?
Because of their wide range of shapes
Which genus includes significant pathogenic species such as H. influenzae and H. ducreyi?
Haemophilus
Where do Haemophilus organisms typically inhabit?
Upper respiratory tract, mouth, vagina, and intestinal tract
What prevents most species of the genus Haemophilus from growing on blood agar plates?
Absence of blood factors for growth
Test your knowledge about Bacteroides fragilis, an anaerobic, Gram-negative bacterium that is part of the normal microbiota of the human colon. Learn about its habitat, role in gastrointestinal function, and its potential to cause infections.
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