Abx and infections pt.2 Flashcards
Why not use Augmentin for everything?
- Cost ($10/15 vs $50)
- 3x more side effects
- Resistance
- In the person exposed, primarily
- Stewardship
- Analogy – moving from studio/1BR apartment
Why risk using amoxicillin rather than clindamycin?
Risk of using amoxicillin:
* No risk if the reaction is?
* Any non-SJS rash history to amoxicillin? re-exposed?
* Risk of a severe reaction is ?
* Risk for sever reaction if initial ‘allergy’ was immediate onset, ?
Why risk using amoxicillin rather than clindamycin?
Risk of using amoxicillin:
* No risk if the reaction is GI, headache, yeast infection, family history
* Any non-SJS rash history to amoxicillin, re-exposed to amoxicillin 93-94% tolerate with no subsequent reactions
* Risk of a severe reaction is 0.001%
* Risk for sever reaction if initial ‘allergy’ was immediate onset, 0.29%
Risk of Clindamycin
Among oral antibiotics commonly prescribed by dentists, clindamycin has
the highest fatal (2.9/million prescriptions), serious (233.2/million
prescriptions), and overall (337.3/million prescriptions) ADR rates.
* Double any other dental antibiotic
* >15 times higher than amoxicillin
* Amoxicillin has the lowest fatal
(0.1/million prescriptions), serious
(11.9/million prescriptions), and overall
(21.5/million prescriptions) ADR rates
Risk of C. difficile Infection By Antibiotic
* Clindamycin
* Augmentin
* Cephalexin
* Amoxicillin
* Penicillin
- Clindamycin 25-fold increased risk (greatest risk)
- Augmentin 8.5-fold
- Cephalexin (Keflex) 3-fold
- Amoxicillin 2-fold
- Penicillin 1.8-fold
Recurrence and Mortality of c dif
Antibiotic Duration Impacts CDI Risk
use under 3 days to decrease risk
PPI and Abx
lower ph of stomach reduicing sporicidal emzyme ability
probiotic use with Abx?who can benefit?
May consider for higher risk individuals:
* 65yo+
* recent hospitalization or nursing home
* weak immune system (HIV/AIDS, cancer, or
taking immunosuppressive drugs)
* previous C. diff infection
* taking proton pump inhibitors
amox or clindamyacin?
amox when no contraindications for type 1 allergy
low risk signs for amoxicillin allergy
tree analogy
Why is the Penicillin Allergy Label Bad?
Cephalosporins
* beta-lactamases?
* Active against?
* generations?
* Each successive generation includes?
* side effects?
* Safely tolerated in?
* Poor against?
- Most beta-lactamases do not reduce activity of cephalosporins
- Active against Gram negatives producing b-lactamase
- Several “Generations”
- Each successive generation includes more Gram-negative activity
- Limited side effect profile
- Safely tolerated in penicillin intolerance history
- Poor against anaerobes (particularly gram-)
ceph moa
binds PBP
1st gen cephs names
1st Generation Cephalosporins
* Excellent coverage of?
* gram activity? spp?
* oral gram -?
- Excellent GRAM POSITIVE Coverage – Strep. spps. & Staph aureus
- some gram negative activity:
- Proteus, E. coli, and Klebsiella (PEcK)
- Limited oral gram negatives- NO P. gingivalis
kelfex Rx
RX: Cephalexin 500mg po QID x 5 days
2nd gen cephs names
2nd gen cephs
* gram coverages?
* oral gram -?
- Still excellent GRAM POSITIVE Coverage – Strep. spps.
- Some additional gram negatives:
- Morexella, Haemophilus, Enterobacter, Neisseria
(More HEN PEcK) - Still overall limited oral gram negative- YES P. gingivalis
when would 1st and 2nd gen cephs be used in dentistry
1st gen more used for prophylaxis/allergies where as 2nd gen can be used for infections due to increased gram - coverage, however amoxicillin is preferred
Cefuroxime rx
Cefuroxime 500mg po BID x 5 days
less doing with longer t1/2
how can we use 1st and 2nd gen ceph in mouth
: may be used for early odontogenic infections. (no perio indications)
ndividuals allergic to amoxicillin may receive cephalexin?
ndividuals allergic to amoxicillin may receive cephalexin as long as the reaction was not anaphylactic-like.
Metronidazole (Flagyl)
●Bactericidal against all?
spp?
●MOA
●additional targets?
●Bactericidal against all obligate ANAEROBES
Bacteroides spps. and Fusobacterium
●Breaks DNA structure directly through production of free radicals via redox rxns
●Antiprotozoal: amoeba (Entamoeba), Trichomonas, Giardia.
metro ADRs
- Metallic taste, dry mouth
- Dark urine
- Skin rashes
- Disulfiram reaction? (headache, flushing, N/V) avoidance of alcohol no longer required
metro interactions
other antimicrobials increasing warfarin con./ INR
TMP-SMX and fluconazole
warfarin interactions
majority activtity from s isomer which is increased due to CYP2C9 inhib= INR increased
Empiric Warfarin Dose Reduction with metro
Metronidazole (Flagyl)
●General Medical Uses:
●Resistance ?
●General Medical Uses:
Deep space abscesses
Gastrointestinal infections
●Resistance is not a problem. Given IV or orally.
Metro DENTAL USES:
●Combined with? used when?
nickname
●Management of?
●Rx:
●Combined w/ -Lactams - 1st Line for serious orofacial
infections
“poor man’s Augmentin”
●Management of refractory or progressive periodontitis.
●Rx: Metronidazole 500mg po Q8h x 5days, #15
metro coverage
General Antibiotic Mechanisms of Action: cell wall action vs non-cell wall active
Protein Synthesis Inhibitors
- Clindamycin – STATIC
- Macrolides - STATIC
- Tetracyclines – STATIC
- Clindamycin, Macrolides, Tetracyclines MOA
inhibits RNA to stop pro synthesis (30s/50s subunit)
Clindamycin (Cleocin™) – IV and PO
Activity for?
* gram + spp?
gram- spp? Problem?
* No cover of?
Activity for Gram Positives and Anaerobes
* Strep. & Staph. including MRSA
* Anaerobic gram negatives: Actinomyces, Bacillis, Bacteroides (increasing resistance)
* No aerobic gram-negatives
clindamyacin clinical adv
- PVL toxin inhibition
- Biofilm inhibition/penetration
clindamyacin Disadvantages
* infection?
* oral suspension?
* High doses of oral clindamycin (>450 mg Q6H) may cause?
- C. difficile infection
- Clindamycin oral suspension unpleasant taste
- High doses of oral clindamycin (>450 mg Q6H) may cause esophagitis
Clindamycin (Cleocin™) – IV and PO Additional Dental Advantages
●penetration?
●Minimal concerns with?
●In dentistry:
●High penetration into saliva, gingival tissues, and bone
●Minimal renal concerns
●In dentistry: Late or severe endodontic infections & abscesses
with severe PCN allergy