Gram +ves Flashcards
describe the process of start smart
take history and begin appropriate antibiotic
then focus and clinical review after 48 hours and potentially switch antibiotic/route/dosage etc or stop the antibiotic
name a coagulase negative staph
staph epidermidis
name 3 types of enterococci
E. faecalis
E. feacium
vancomycin resistant enterococcus
3 types of bacilli?
listeria monocytogenes
clostridia (C. diff, C. perfringens - wound infections)
corynebacterium (diptheroids - not the same as diphtheria)
6 examples of Beta lactam antibiotics?
penicillin flucloxacillin amoxicillin cephlasporins piperacillin/tazobactam carbepenems
what is the significance of the Beta lactam antibiotics?
if you are allergic to one, probably allergic to the others
- allergy is due to a degredation product of the beta lactas
general rule for sepsis antibiotics?
always IV apart from C. Diff
structure of penicillin?
beta lactam ring is like a garage on the side of a thiazolidine ring which is like a house with a roof
what can deactiviate beta lactam antibiotics?
beta lactamase
what is bioavailability?
the proportion of a drug or other substance which enters the circulation when introduced into the body and so is able to have an active effect.
what is the importance of bioavailability?
different routes of delivery result in different bioavailability due to absorption
therefore different routes are used depending on severity of infection (i.e sepsis is usually IV while mild infections can usually be treated orally)
why are Beta lactam antibiotics needed to be given several times a day?
mode of action depends on amount of time you spend above the minimum inhibitory concentration (concentration required to inhibit the organism)
why does gentamicin only need to be given once per day?
concentration dependant killing
what drugs act via concentration dependant killing?
aminoglycosides (gentamicin)
quinolones (….floxacins)
how can the structure of a target site affect antibiotic action?
more difficult for antibiotics to get into areas with tight junctions (CNS, eyes, prostate)
are members of same class all the same?
no
can have different spectrum and site penetration
describe characteristics of strep?
gram +ve cocci in chains
catalase positive
nutritional fastidious, require complex media, preferably supplemented with blood
strep are facultative anaerobes, what does this mean?
grow aerobically and anaerobically - technically though they do not use oxygen in metabolism, some are capnophilic (grow well in high CO2), some prefer anaerobic conditions for growth
alpha vs beta vs gamma haemolysis?
alpha = partial = green beta = complete = clear/yellow gamme = none = no colour change
what is the lancefield antigen/classification?
classification of strep via differences in carbohydrate but not useful for all strep
group A beta haemolytic strep?
strep pyogenes
- pharyngitis, skin
- immunologic sequelae
group B beta haemolytic strep?
strep agalactaiae
- pregnancy and neonates
what type of strep is strep pneumonia?
alpha haemolysis
strep bovis renamed to what?
strep gallollyticus
- typical endocarditis pathogen
additional investigation in strep gallollyticus and why?
colonoscopy as associated with carcinoma
what can strep pneumonia cause?
otitis media
pneumonia
meningitis
what is the general antibiotic for strep pneumonia and when is this not the case?
penicillin (works by binding enzymes needed to synthesise peptidoglycan)
not after travel to certain countries due to resistant strains which exist
what is penicillin G?
benzylpenicillin AKA IV penicillin
what is oral penicillin known as?
phenoxymethylpenicillin
where do enterococci live int he body?
Gut
- i.e can occur from perforation, biliary etc
can also occur in the heart causing endocarditis
what is the main antibiotic for enterococcus?
amoxicillin IV
step down = amoxicillin or co-trimoxazole oral
what is used for enterococcus if penicillin resistant?
vancomycin
drug of choice in sepsis for staph aureus?
flucloxacillin
what drug is used for staph aureus sepsis if penicillin allergic or MRSA?
vancomycin IV
what other drugs can be used for staph aureus not causing sepsis?
oral doxycycline
cotrimoxazole
clindamycin
describe staph epidermidis?
coagulase negative
less virulent than staph aureus
most are flucloxacillin resistant
only a likely cause of endocarditis in specific stories (i.e pacemaker, prosthetic valve, present in all cultures)
relevant gram +ve bacilli?
listeria (gastroenteritis)
bacillus (reheated rice)
clostridium (C. Diff)
why is oral vancomycin used instead of IV in C. Diff?
so it acts directly on bacteria in stomach (topical treatment)
