Pathogenic Bacteria Flashcards
Staph aureus? Characteristics?
Gram positive cocci:
- abscess-forming bacteria
- can also cause internal infection at joints, discs, pneumonia and infective endocarditis
- can also live harmoniously
- sticks well to prostheses
Coagulase enzyme +ve:
- converts fibrinogen to fibrin (clotting - camouflage)
- resistant to penicillin due to beta-lactamase presence
Common shapes of bacteria? Description?
Cocci:
+ve; circular with peptidoglycan layer
-ve; circular with lipopolysaccaride layer
Rod:
+ve; long rod-shaped peptidoglycan later
-ve; long rod-shaped lipopolysaccardie layer
Cocci? Gram classifications? Examples?
+ve: strep and staphy
-ve: neisseria meningitidis/gonorrhea and moraxella catarrhalis
Rods? Gram classifications? Examples?
+ve: listeria, clostridium difficile/botulinium/perfringens/tetani and bacillus anthracis
-ve: salmonella, E.coli, campylobacter, shigella, pseudomonas, haemophilus influenza and bacteriodetes
Antibiotics? Ranges? Examples?
Broad spectrum: eliminates all bacteria (good and bad)
Narrow spectrum: eliminates a specific type of bacteria
Gentamycin: -ve rods
Coamoxiclav: +ve cocci and -ve rods
Amoxicillin: +ve cocci
Streptococci? subtypes?
alpha-haemolytica: (turn blood agar green) pneumoniae; causes infective endocarditis
beta-haemolytica: (urn blood agar clear) A-G
Strep throat: can cause rtheumatic/scarlet fever
- abs cross react with the tissue causing problems
Beta-haemolytic streptococci? subtypes, characteristics and examples?
A: pyogenes; sore throat and necrotising fasciitis
B: agalactiae; neonatal sepsis (meningitis), carried in genital tract
D: enterococcus faecalis; non-haemolytic in gut but can cause UTI
Clostridium difficile? Characteristics?
- Present in healthy gut (+ve)
- causes of diarrhoea (toxin production)
- increased risk with antibiotic use (disrupt gut flora)
- detect by ELISA
Clostridium perfringens? Characteristics?
- present in soild and commensal in human gut and faeces
- pathogenic in food casuing food-poisoning (enterotoxin)
- cause gangrene
Clostridium tetani? Characteristics?
- toxins cause tetanus (uncontrolled msucle spams due to loss of inhib at NMJ
- modified toxin used for immunisation
Neisseria meningococcus? Characteristcs?
- causes meningitis (inflammed meninges)
- important when isolated from a sterile site (CSF)
- PCR available
- ve
Neisseria gonorrhoeae/ Characteristics?
- causes urethritis (men) and pelvic inflam (women)
- sexual contact
- ve
Moraxella catarrhalis? Characteristics?
- cause resp tract infect
- especially in underlying lung pathology
- ve
E.coli? Characteristics?
- human and animal reservoirs
- virulence mech via pili, capsule, endo.exotoxins produced
- ferments lactose
- 160 serotypes
- cause UTIs
- Enterotoxogenic: traveller’s diarrhoea
- Enterohaemorrhagic: bloody diarrhoea
Salmonella enterica? Characteristics?
- self limiting enterocolitis with or without diarrhoea
- 2nd most common cause of bacteria diarrhoea