Antimicrobials Flashcards
Gram stain results and meaning
o Positive is PURPLE- one cell membrane with peptidoglycan outer layer
o Negative is NAGENTA- 2 cell membrane with peptidoglycan in-between and lipposacchurides on outside
Gram positive Cocci
Staph- coagulase +- aureus, - epidermis and strep
Gram Negative Bacilli
A Actinomyces (branching) B Bacillus (cereus, athracis) C Clostridium (difficile, perfringens, botulinum, tetani) D Diphtheriae (Corynebacterium diphtheriae) L Listeria
Broad Spectrum Meds
These Meds Can Cover T Tazocin (Piperacillin/Tazobactam) M Meropenem C Co-amoxiclav C Ciprofloxacin
Resistant mechanisms to antibiotics
Bypass Enzymes (beta-lactamases) Accumulation impaired (tetracyclines) Target modified (MRSA)
Which antibiotics inhibit cell wall synthesis
Penicillin
Cephalosporins
Carbapenems
Glycopeptides
Which antibiotics interrupt protein synthesis
Chloramphenicols Oxazolidnones Aminoglycosides Tetracyclines Macroloides
Which AB inhibit DNA synthesis
Fluoroquinilones
Nitroimidazoles
Which AB inhibit RNA synthesis
Rifamycin
Which AB inhibit folate synthesis
Sulfonamides
Diaminopyrimidines
What types of microbes are b lactase effective against
Penicillin- +
Cephs- as generation increases more negative
Carbs- wide spectrum
What types of microbes are vancomycin effective against
MRSA, C diff
What types of microbes are aminoglycosides effective against
Gram - sepsis
What types of microbes are tetracyclines effective against
Intracellular- chlamydia
What types of microbes are macrolides effective against
Gram + usually PCN allergy
What types of microbes are chloramphenicols effective against
Bacterial Conjunctivitis
What types of microbes are fluoroquinilones effective against
Negative
What types of microbes are Nitroimidazoles effective against
Anaerobes and protozoa
What types of microbes are rifamycin effective against
Mycobacteria
What is used for cellulitis
Flucloaxcillin
What Is used for pharyngitis
Benzylpenicillin
What is used for CAP
Mild- amoxicillin
Servere- Co-amox and clarithromycin (for atypical)
What is used for HAP
Non servere- Coamox/doxy
Servere- Piptazobactam/Cef+gent
MRSA- Vanc
Pseudo- Piptazobactam / Tazocin
What is used for bacterial meningitis
Ceftriaxone
What is used for community and nosocomial UTI
Com- Trimethoprim/Nitro
Noso- Co amox
What is used for C diff
Metronidazole
If fail- vanc
What is used in sepsis
Tazocin/cef or Met+ Gent
What is the MIC
Minimum inhibitory concentration
o This is the minimum drug concentration that is required to inhibit the growth of the organism in a culture
Type 1 antimicrobial pattern of activity
o Peak above the MIC (Cmax) is the MOST IMPORTANT factor (these drugs have concentration-dependent effects)
o Therefore, aminoglycosides are given as one big dose once a day, to try and get the Cmax as high as possible
o The higher the Cmax the better the clinical outcome for infections treated with aminoglycosides
Type 2 antimicrobial pattern of activity
These are time-dependent, so you want to maximise the time above the MIC
e.g penicillin
Type 3 antimicrobial pattern of activity
o Sort of a combination of Type I and Type II
o The AUC (area under curve) above the MIC is the MOST IMPORTANT factor (both concentration and time-dependent effects)
o Infusions can maintain an AUC above the MIC
e.g vancomycin
What is the eagle effect
Penicillin works by inhibiting cell wall synthesis, but cell wall synthesis only occurs when the bacteria are dividing
o In cases of extremely high bacterial burden, bacteria may be in the stationary phase of growth - hence penicillin will have little effect
What antibiotics commonly cause c diff
Cephalosporins
Cirpro (quinilone)
Clindamycin
