Classification of Pathogenic Bacteria Flashcards
What are the two types of aerobic gram positive cocci?
Staphylococci (clusters)
Streptococci and enterococci (chains)
What aerobic gram positive bacteria are clusters?
Staphylococci.
What aerobic gram positive bacteria are chains?
Streptococci and enterococci.
What test do staphylococci undertake?
Coagulase test.
What does the coagulase test do?
Classifies staphylococci as positive or negative- they can be further isolated as MSSA/MRSA.
What is an example of a positive coagulase staphylococci?
Staphylococcus aureus- major pathogen, commensal in nose, wide range from boils to septicaemia.
What are staphylococcus aureus resistant to and why?
Penicillin due to production of penicillinase (B-lactamase).
What more serious complication is seen in staphylococcus aureus?
Methicillin resistance- MRSA, becomes a major clinical issue for infection prevention and control in hospitals.
What are examples of negative coagulase staphylococci?
S. epidermis, S. haemolytic, S. saprophytic, S, lugunensis, many commensals, form biofilms, pathogens in present of foreign objects.
When do negative coagulase staphylococci often become pathogens?
In presence of foreign agents (e.g. foreign bodies/transplant).
What structure are streptococci/enterococci?
Chained.
What are the classifications of streptococci/enterococci?
Alpha-haemolytic
Beta-haemolytic
Non-haemolytic
What do alpha-haemolytic streptococci do to blood agar?
Turn green.
What do beta-haemolytic streptococci do to blood agar?
Turn clear.
What streptococci is alpha-haemolytic?
Strep. pneumonia.
What does Strep. pneumoniae do?
Pneumonia, meningitis, septicaemia.
What are beta-haemolytic streptococci ordered by?
Type A-G.
What streptococci is beta-haemolytic Type A?
Strep. pyogenes.
What does Strep. pyogenes do?
Pharyngitis, meningitis, septicaemia.
What is an anaerobic gram positive bacteria?
Clostridium difficle.
What does C. difficle do?
Causes diarrhoea through toxin production- assymptomatic gut carriage.
What are the types of gram negative pathogenic bacteria?
Aerobic- E.coli, Salmonella, Pseudomonas, Campylobacter spp, helicopter pylons, haemophilus influenzae.
Anaerobes- polymicrobial infection e.g. bacterioides.
What does Escherichia coli. do?
Found in human/animal reserves, causes diarrhoea.
Many virulence mechanisms, ferment lactose.
Does E. coli ferment lactose?
Yes.
What does salmonella do?
Causes self-limiting enterocolitis, can invade bloodstream causing septicaemia, no fermentation of lactose.
How does salmonella cause sepsis?
Invasion of bloodstream.
Does salmonella ferment lactose?
No.
What do pseudomonas do?
Soil/water coloniser, can contaminate medical equipment causing sepsis, feared pathogen in cystic fibrosis.
How do pseudomonas cause sepsis?
Contamination of medical equipment.
What are pseudomonas the feared pathogen in?
Cystic fibrosis.
What do campylobacter spp. do?
Found in domestic animals/chickens, spread through faecal-oral route, cause foul-smelling bloody diarrhoea.
How are campylobacter spp. spread?
Faecal-oral route from domestic animals/chickens.
What do helicopter pylons do?
Damage mucus, cause gastrointestinal ulceration, curved rod shape and human stomach commensal.
What do helicopter pylons increase the risk of?
Gastric adenocarcinoma.
What shape are helicopter pylons?
Curved rods.
What do haemophilia influenzae do?
Cause respiratory tract infection.
What shape are haemophilia influenzae?
Mixed appearance.
What are anaerobic gram negative bacteria an example of?
Polymicrobial infection.
What are an example of gram negative anaerobes?
Bacterioides.
What are 2 examples of bacterioides?
Prevotella.
Porphyromonas.
