Gram-negative bacteria Flashcards
What are virulence factors?
Any product or strategy that contributes to pathogenicity
Name some colonisation factors
adhesins, invasins, nutrient acquisitio
What shape are coliforms?
Rod-shaped
Are coliforms motile?
Most are due to peritrichous flagella
What do coliforms colonise?
The intestinal tract
True or false: negative bacteria are facultatively anaerobic
True
Enterobacteriaceae consists of multiple gram negative ___-shaped bacterial species
rod
Lactose fermentation produces ____
acid (used to distinguish between bacteria)
Which 2 bacteria show lactose use (ferment it to make acid) on appearance on MacConkey?
Escherichia coli and Klebsiella pneumoniae
MacConkey-lactose agar shows lactose fermenters in what colour?
Red (due to acid)
What colour do lactose fermenters turn phenol red in media?
Yellow
Do either salmonella or shigella ferment lactose?
No, neither
What are the flagellum made of?
Protein
What are the principal infections caused by pathogenic E. coli
Wound infections, UTIs, Gastroenteritis, Travellers’ diarrhoea, bacteraemia, meningitis (infants)
ETEC stimulates a chlorine transporter in the intestinal lumen to release i___ and w___ through toxins which leads to watery diarrhoea
ions and water
What does shigellosis cause?
Severe bloody diarrhoea
Where is shigella common?
In developing countries where sanitation is poor
True of false: Shigella is acid-tolerant
True
How does shigella spread?
Person-to-person, contaminated water and food
Shigella enters through colonic _ cells which overlie lymphoid follicles and deliver antigens to underlying immune cells
M
How does the shiga toxin in shigella cause cell death?
inhibits protein synthesis
What are the 2 species of salmonella?
S. enterica and S. bongori (rare - contact with reptiles)
What are the 3 forms of salmoellosis caused by S. enterica
Gastroenteritis
Enteric fever - typhoid
Bacteraemia
How does salmonellosis occur?
invades gut epithelium
Transcytosed to basolateral membrane
Enters submucosal macrophages
Intracellular survival
Pseudomonas aeruginosa
Ubiquitous (found everywhere), free-living, motile, rod-shaped, opportunistic, resistant to multiple antibiotics
Thick mucus in cystic fibrosis increases risk of infection via m____ version of P. aeruginosa
mucoidal
Vibrio Cholerae
Facultative anaerobe (makes ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation), saline environments
True of false: Cholera is the most severe diarrhoeal disease
True
How is V. cholerae spread?
Faecal-oral (not person-to-person)
Most cases of V. cholerae can be treated with ___
ORT (oral rehydration therapy)
Campylobacter shape
Spiral rods
The flagella of campylobacter are either u_____ or b___
unipolar or bipolar
Symptoms of campylobacter
Mild to severe diarrhoea, often with blood
True or false: salmonella is the most common cause of food poisoning in UK and US?
False - campylobacter is
Helicobacter pylori shape
Spiral-shaped
Helicobacter pylori plays a major role in gastritis and p__ u___ disease
peptic ulcer
Haemophilus influenzae is an opportunistic injection seen mainly in young children and adult _____
smokers
H. influenzae can penetrate the n__________ epithelium
nasopharyngeal
H. influenzae has built resistance to phagocytosis and c_____ system
complement
Bordetella pertussis
Short rods, fastidious (depends on cleanliness)
What is pertussis also known as
Whooping cough
True or false: Bordetella pertussis is highly contagious through aerosol transmission
true
Legionella pneumophila
Immunocompromised, causes severe inflammatory pneumonia, infection from man-made aquatic environments
Can legionella pneumophila replicate within alveolar macrophages
Yes
Legionella pneumophila r______ within freshwater protosoa (intracellular parasite of amoeba)
replicates
Bacteroides
Non-motile rods, commensal flora *large intestine), opportunistic
What is the most frequent cause of anaerobic infections?
Bacteroides (B. fragilis)
Bacteroides is often present in polymicrobial infections with e_______
enterobacteria (Presence of facultative anaerobes depletes O2, allowing anaerobes such as Bacteroides to proliferate)
Neisseria is a non-flagellated d_____
diplococci
What does neisseria meningitidis cause?
Neisseria gonorrhoeae causes
Gonorrhoea (second most common STD worldwide)
Can gonorrhoea be asymptomatic?
Yes
Gonococci are non-c____
capsulated
Spirochaetes are longer, slender, h_____ and highly flexible
helical
Borrelia burgdorferi causes what disease?
Lyme disease
