Bacterial Pathogens. Know your enemy. Flashcards
What are the 2 main types of bacteria?
G+ve and G-ve
What differentiates G+ve from G-ve bacteria?
- G+ve has a thick peptidoglycan wall and stains blue/violet with gram stain.
- G-ve has thin peptidoglycan wall under a membranous outer layer. It stains red/pink under Gram stain.
What two froms do bateria take when seen under the microscope?
- Diplococci (pairs of grapes)
* bacilli (Rods)
Name 3 types of G+ve cocci?
- Staphylococci
- Streptococci
- Enterococci.
Name 4 types of G+ve bacilli?
CCBL
- Corynebacteria eg C. diptheriae (diphtheria)
- Bacillus anthracis (anthrax)
• Listeria monocytogenes (listeria)
–Meningitis in elderly, immunosuppressed & pregnant
–Sepsis/meningitis in neonates
• Clostridium sp.: spore-forming
–C. tetani – tetanus
–C. botulinum – botulism
–C. perfringens – gas gangrene, food poisoning
–C. difficile – antibiotic-associated diarrhoea, pseudomembranous colitis
Name 2 types of G-ve cocci
nm
• Neisseria (Gram-negative diplococci)
–N. meningitidis – meningococcus – sepsis, meningitis
–N. gonorrhoeae – gonococcus - gonorrhoea
• Moraxella catarrhalis
–Respiratory infection
Name 7 types of G-ve bacilli
- Escherichia coli & other Enterobacteriaceae (‘coliforms’), e.g. Klebsiella, Proteus, Serratia
- Haemophilus
- Salmonella, Shigella
- Campylobacter (‘seagulls’;’commas’)
- Pseudomonas aeruginosa
- Acinetobacter sp
- Stenotrophomonas maltophilia
What are the 2 major bacteria that live on the skin? and 2 others and a yeast?
- Staphylococcus and streptococcus
- Corynebacteria (‘diphtheroids’)
- Propionibacteria
• Yeasts
–Candida sp
–Pityrosporum
–Trichosporum
Which is worse, staphyloccus coagulase -ve or +ve?
Staph aureus is the only coagulase +ve staph and is by far the worst!
Name 2 staphylococcus coagulase -ve bacteria that can cause problems?
- S. epidermidis is a commensal of the skin, but can cause severe infections in immune-suppressed patients and those with central venous catheters.
- S. saprophyticus is part of the normal vaginal flora, is predominantly implicated in genitourinary tract infections in sexually-active young women.
What types of streptococcus bacteria are there?
- Alpha-haemolytic
* Beta-haemolytic
What is the primary group A streptococcus beta haemolytic bacteria that I should be aware of?
Streptococcus pyogenes.
What can Streptococcus pyogenes cause?
–Puerperal sepsis
–Tonsillitis
–rheumatic fever & glomerulonephritis
–Necrotising fasciitis
–Cellulitis, skin and soft tissue infections
–Scarlet fever
–Toxic shock syndrome
What is the primary group B streptococcus beta haemolytic that can cause issues with neonates and the elderly?
• Strep. agalactiae
–Neonatal sepsis and meningitis
–Skin and soft tissue/cellulitis
–Bacteraemia/Osteomyelitis
What is a yeast that lives on the skin and what can it cause?
• Candida albicans
–thrush – genital, oral
–Line infections/bacteraemia in the
• become and issue in immunocompromised/critical care
What are the 2 likely causes of cellulitis?
- Group A streptococci - pyogenes
* Staphylococcus aureus
What are the likely bacteria to be found in the nasopharynx?
- Streptococci (viridans type) (GPC)
- Neisseria (GNC)
- Haemophilus (GNR)
- Moraxella (GNC)
- Mixed anaerobes
- Candida
What is the 3 primary Alpha haemotlytic that I need to be aware of?
- S. pneumoniae – diplococci - pneumonia/meningitis
- S. mutans – tooth decay
- S. bovis - ??association with bowel Ca
Alpha haemolytic strep can ba a cause of sub-acute infective endocarditis
–‘milleri group’- deep abscesses
Streptococcus beta haemolytics are split into groups a+b (and c+d+e+f) what are the most important pathogens of A+B?
Group A = Streptococcus pyogenes
Group B = Streptococcus agalactiae
What are the 2 primary strains of Neisseria?
- N. meningitidis – meningococcal sepsis/meningitis
- N. gonorrhoeae – gonorrhoea, septic arthritis
- Some other sp found as nasopharyngeal flora
whay are the 4 atypical bacteria that can cause pneumonia?
LMCCC
‘Atypical’
- Mycoplasma
- Chlamydophila pneumoniae
- Chlamydophila psittacci
- Legionella
What are the 5 main causes of community acquired pneumonia?
- Streptococcus pneumoniae
- Haemophilus influenzae (COPD)
- Moraxella catarrhalis (COPD)
- Staphylococcus aureus (post-flu/nosocomial)
• Klebsiella pneumoniae
(but often nosocomial)
What are the 3 likely causes of meningitis in adults?
- Streptococcus pneumoniae
- Neisseria meningitidis
- Listeria monocytogenes (elderly, immunosuppressed, pregnant)
What bacterial pathogens are you likely to find in the bowel?
- Enterobacteracieae
- Enterococci
• Anaerobes
–Bacteroides
–Clostridia
- Bifidobacteria
- Lactobacilli
- Candida
What are the 3 main groups of enterobacteriaceae?
- Escherichia coli, Klebsiella sp
- Enterobacter sp, Serratia sp, Citrobacter sp, Morganella sp
- Proteus sp
Are enterobacteriaceae G-ve or G+ve?
G-ve
What pathology can enterococci cause?
- Urinary tract infections,
- Abdominal sepsis
- endocarditis
Name 2 gut anaerobes and what they cause?
•Bacteroides fragilis - bowel sepsis
•Clostridium sp, e.g.:
–C. difficile – antibiotic-associated diarrhoea, pseudomembranous colitis
–Spore-forming
What are the 3 likely types of bacteria to cause bowel sepsis?
–E. coli and other enterobacteriaceae
–enterococci
–anaerobes
What are the 3 most likely causes of UTI’s?
–E.COLI, Proteus or other enterobacteriaceae
–Enterococci
–Staphylococcus saprophyticus (young women)
What are the 2 most likely causes of pylonephritis?
- E. coli
* Proteus
What is the most important environmental oppertunist and where are you likely to see it?
Pseudomonas aeruginosa → likely to show up in hospital esp. ITU
What are the 4 most likely types of bacteria to cause hospital acquired infection?
–Enterobacteriaceae
–Pseudomonads
–MRSA
–If aspirated - anaerobes
