Infectious Diseases (basics) Flashcards
Define Eukaryotes?
cells containing membrane bound organelles e.g. nucleus, mitochondria or chloroplasts, can be unicellular e.g. fungi, or part of a complex multicellular organism e.g. a human
Define prokaryotes?
cells lack any membrane bound organelles – usually unicellular e.g. bacteria and archaea
What are archaea?
- Archaea are a domain of single cell organisms that live at extremes (type of prokaryote)
Describe difference in way DNA is organised in prokaryotes vs eukaryotes?
- DNA in prokaryotes and therefore bacteria is circular including the circular chromosome and plasmids – this is in contrast to eukaryotes where DNA is arranged in a linear fashion e.g. in chromosomes
- prokaryotes can do co-transcriptional translation (all happening at the same time) because nothing is membrane bound
Proteins are synthesised in the ______
ribosome
What is essential for synthesis and regulation of DNA within the bacteria?
folic acid
Explain the process of gram staining and what it involves?
- This allows organisms to be classed as gram positive or negative
- Atypical organisms cannot be classed this way – definition = organisms that cannot be stained or cultured in normal ways
- Gram staining involves first using a crystal violet stain which will stain gram positive organisms purple, then a counterstain which will stain gram negative organisms pink
- Gram staining is to do with differences in thickness of peptidoglycan cell walls
Name 6 gram positive rods?
- Propionibacterium
- Clostridium
- Lactobacillus
- Corneybacteria
- Actinomyces
- Listeria
2 genus of gram positive cocci? How can you differentiate?
streptococci - grow in chains - catalase negative
staphylococci - grow in clusters - catalase positive
2 species of staph that are clinically relevant?
aureus and epidermidis
Describe classification of streptococci?
Alpha haemolytic – viridans and pneumonia
Beta haemolytic (complete) – Group A and Group B
Gamma haemolytic – Enterococcus
Describe neisseria genus?
gram negative cocci in pairs
includes neisseria meningitidis and neisseria gonorrhoea
What are the coliforms? List 3?
COLIFORMS- gram negative non spore forming bacilli
E. coli
Klebsiella
Enterobacter
Pseudomonas shape and gram stain?
gram negative rod
Moraxella Catarrhalis shape and gram stain?
gram negative diplococcus
List 4 gram positive anaerobes?
Clostridium, lactobacillus, actinomyces, Propionibacterium
Name a gram negative anaerobe?
Bacteroides
Define bacteriostatic vs bacteriacidal?
- Bacteriostatic – stops reproduction and growth of the bacteria
- Bacteriacidal – kills the bacteria directly
Antibiotics that inhibit cell wall synthesis?
- Antibiotics that inhibit cell wall synthesis can be split into beta lactam and non beta lactam antibiotics
- Beta lactam – penicillins, carbapenems and cephalosporins
- Non beta lactam – vancomycin and teicoplanin
Antibiotics that inhibit folic acid metabolism?
- Antibiotics that inhibit folic acid metabolism – sulfamethoxazole, trimethoprim, co-trimoxazole (combination of the above 2)
Antibiotic that affects nucleic acid synthesis?
- Antibiotic that affects nucleic acid synthesis – metronidazole – this only converts to active form in anaerobic cells so is only effective against anaerobes
Antibiotics that affect protein synthesis by targetting the ribosome?
- Inhibition of protein synthesis by targeting the ribosome – macrolides, clindamycin, tetracyclines, gentamicin, chloramphenicol
Amoxicillin coverage
widely covers gram positive and some gram negative organisms, covers most strep, enterococcus and listeria
Co-amoxiclav coverage?
widely covers gram positive, gram negative and anaerobes
Metronidazole coverage?
treats anaerobic infections
Gentamicin coverage?
mainly gram negative coverage against pseudomonas, E. coli, proteus, klebsiella, Enterobacter, can also treat Staph
Vancomycin coverage?
coverage for gram positive organisms, oral vancomycin is used for C diff GI infection
Doxycycline coverage?
broad spectrum covering gram positive, negative and anaerobes and some atypical infections
Clindamycin coverage?
active against gram positive and anaerobes
Clarithromycin coverage?
gram positive and atypical organisms
Ciprofloxacin coverage?
gram negative cover
6 antibiotics you could get gram positive cover with?
Amoxicillin
Co-amoxiclav
Vancomycin
Doxycycline
Clindamycin
Clarithromycin
4 antibiotics you could get gram negative cover with?
Gentamicin
Doxycycline
Co-amoxiclav
Ciprofloxacin
4 antibiotics you could get good anaerobe cover with?
Metronidazole
Doxycycline
Clindamycin
co-amoxiclav
Define sepsis?
- Dysregulated host response to infection (overreaction by host to presence of infection)
- Essentially clinically can view it as NEWS > 5 and signs of infection
Define septic shock?
- Septic shock is a subset of sepsis where there is circulatory and cellular/ metabolic dysfunctions associated with high risk of mortality
- Criteria for septic shock: persistent hypotension requiring vasopressors to maintain MAP greater than or equal to 65, lactate greater than or equal to 2 mmol (despite adequate volume resuscitation)
Explain why lactate is measured in sepsis?
- Lactate is measured in sepsis as a high lactate suggests hypoperfusion of tissues (as they are switching to anaerobic respiration)
What is the sepsis 6?
- Sepsis 6 needs commenced in 1 hour: take blood cultures, measure urine output, take lactate, give empirical antibiotics, give high flow oxygen, give fluids
What type of antibiotic is ceftriaxone? What does it cover? What is it especially good for?
cephalosporin
it is broad spectrum covering both gram positive and gram negative
it is good for CNS infections - it reaches a high bacteriacidal titre in the CSF and persists at the site of infection longer than any other beta lactam
(ceftaxime is similar and also good for this)
What antibiotic is used to treat C diff infection?
ORAL vancomycin
As well as bacterial infection what can metronidazole also treat?
some parasitic infections
What antibiotic can treat some parasitic infections?
metronidazole
Co-amoxiclav covers gram negative, positive and anaerobes but does not cover?
pseudomonas
Pseudomonas is sensitive to ?
ciprofloxacin
Name an antibiotic that cover MRSA?
vancomycin
C diff treatment?
1st line is oral vancomycin
2nd line is for patients who fail to improve after 7 days or worsen on oral treatment - findaxomicin twice daily for 10 days or oral vanc plus Iv met
choose oral vanc plus IV met if life threatening infection
