bacteria/ abx

  1. what is augmentin?
    • amoxycillin trihydrate (B lactam antibiotic) -
    • w
    • potassium clavulanate (B lactamase inhibitor)
    • -> abx w inc spectrum of action and restored efficacy against amocxicillin-resistant bacteria that produce B-lactamase
  2. how do b-lactam antibiotics work?
    • attack cell walls of bacteria (inhibit the synthesis of the peptidoglycan layer of bacterial cell walls). - bacteria develop resistance by synthesizing beta-lactamase (attacks b-lactam ring)
    • used in prophylaxis and rx of bacterial infections caused by susceptible organisms.
    • mainly active against gram-positive bacteria.
    • broad spectrum b-lactam abx is active against various gram-neg organisms.
  3. what are some common b-lactam abx?
    • penicillins: flucloxacillin (narrow s), amoxicillin/ampicillin (mod s), co-amoxiclav (broad s)
    • cephalosporins: cephalexin(mod s), cefaclor (mod s), ceftriaxone (broad spectrum)
    • carbapenems and penems: imipenem
    • monobactams: nocardicin
    • b-lactamase inhibitors: clavulanic acid
  4. what colour do gram-positive bacteria stain?
    • stained dark blue or violet by gram staining - able to retain crystal violet stain bcoz of high amount of peptidoglycan in the cell wall.
    • gram-pos cell walls typically lack outer membrane of gram-neg bacteria.
  5. what is the structure of gram positive bacteria?
    • cytoplasmic lipid membrane
    • thick peptidoglycan layer
    • capsule polysaccarides (only in some species)
    • flagellum (only in some species)
  6. what is the hierarchy of gram positive bacteria?
    • gram positive:
    • bacilli:
    • non spores = corynebacterium, listeria,
    • spore-forming = clostridium- obligate anaerobe, bacillus - facultative anaerobe
    • cocci:
    • staphy (catalase +)
    • -S. aureus (coagulase +)
    • - (coag -) S. epidermis, S. saprophyticus
    • strep (catalase -)
    • - b-haemolytic (clear) - pyogenes or agalactiae
    • - y-haemolytic - enterococcus, E. faecalis, E. faecium
    • - a-haemolytic (green) - pneumonia, viridans mutans, sanguis
  7. what is rifampicin used for?
    • treats mycobacterium infections incl. tb and leprosy
    • used for tb for 6-12/12 w isoniazid, ethambutol, pyrazinamide
    • stop etham and pyra after 2/12
    • also used for
    • rx of MRSA w fusidic acid
    • prophylactically for neisseria meningitidis
    • listeria species, neisseria gonor, haem inf, legion. pneumophilia (test sensitivity 1st)
    • enterobacteriaceae, acinetobacter and pseudomonas resistant
  8. what is amoxycillin?
    • mod. spectrum bacteriolytic
    • b-lactam penicillin (mainly gram pos, a little gram neg)
    • better absorbed following oral adminnthan other b-lactams
    • rx for cystic acne
    • s/e (as for other b-lactams):
    • n and v, rashes, abx assoc colitis, diarrhea
  9. what is penicillin?
    • derived from penicillium fungi
    • 1st drugs effective against syph and staph
    • many bacteria are now resistant
    • all pens are b-lactams - used usually for gram-pos
  10. what are gram neg bacteria?
    and what is their heirarchy?
    • counterstains red (safranin)
    • have lipopolysaccharide outer membrane
    • gram neg
    • coccobacilli:
    • h.influenzae
    • B. pertussis
    • Brucella
    • F. tularensis
    • P. multocida
    • L. pneumophila
    • cocci: neisseria
    • N. meningitidis
    • N. gonorrhoeae
    • bacilli:
    • lactose + = klebsiella, e.coli, enterobacter
    • lactose - =
    • -oxidase + (V. cholerae, P.aeruginosa),
    • -oxidase - (P. mirabilis, H. Plori, S dysenteriae, Salmonella, Y. pestis, Y. enterolitica)
    • -strict anaerobe (B fragilis)
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bacteria/ abx
bacteria/ abx