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Why is it important to know the correct drug to treat?
Because there is a growing amount of antibiotic resistence
What do we need to know to chose an antibiotic?
1. The SOURCE of the pathogen
2. Common PATHOGENS associated with that infection.
3. Which antibiotics are ACTIVE against that type of pathogen.
4. What is the patients risk for a RESISTANT organism.
5. SIDE EFFECTS of antibio tx
6. What is the appropro DOSE and route.
The hallmark of infection is?
Controlled elevation of temp.
Note, fever is not always caused by infection. Thrombus, surgery, autoimmune disease, etc.
Does the lack of fever rule out infection?
No, patients can be infected without fever. Ex. Elderly, Immunosuppressed and those taking antipyretic meds.
Normal range of WBCs is?
4000-11000 cells/mm
Define bandemia (left shift)?
This is an increase in the percentage of immature band nutriphils.
What does leukocytosis tell the practitioner?
Nothing, it does not rule in or out infection.
Leukopenia is a sign of?
Severe infection, because WBC are being used so quickly the bone marrow cannot keep up.
Are fever and WBC specific signs?
Fever and WBC are not specific signs
Microbiological cultures are important because...
They confirm the diagnosis and identify the pathogen.
Every attempt should be made to obtain cultures prior to antimicrobial initiation.
What does a gram stain tell the practitioner?
If dye taken up then gram pos (blue)
If not taken up then gram neg (pink)
Why won't gram neg take a stain?
Because it has a lipid polysaccaride outer membrane that prevents the stain from entering.
When is a gram stain done?
it is dependent on the sight of the sample. Blood cultures have the gram stain done after incubation and non-blood cultures have it done before incubation.
Emperic therapy is treatment of?
The likely pathogens. It includes the use of broad spectrum antibiotics.
What is the MIC?
Minimal Inhibitory Concentration. It is the minimal concentration needed to inhibit growth in-vitro
How is the MIC tested/ the susceptibility tested?
Broth Dilution
What does one do with the MIC?
It is compared to the break point, which is the MIC value that seperates bacteria that are likely to respond to a specific drug treatment from those which are not.
What is the break point used for?
guide antibiotic selection. Bacteria can be sensitive, resistant, or intermediate.
Define de-escalation
important strategy that helps to limit antibiotic utilization and resistance. Changes from the broad emperical spectrum to a narrow spectrum.
Four types of bacteria
Gram positive
Gram negative
Gram positive include?
Gram negatives include?
Haemophilus spp, Ecoli, klebsiella ssp, enterobacter spp, proteus spp, psuedomonas aeruginosa
Anaerobes include?
Bacteroides Fragillis
Atypicals include?
Respiratory pathogens: chlamydia pneumoniae, mycoplasma pneumoniae, legionella pneumoniae
(these are seen with comm aquired pnemo)
Types of antibacterial action include?
Bacteriostatic and bacteriocidial
Bateriostatic is defined as?
The antibiotic inhibits cell replication, does not cause cell lysis. However, it requires a strong immune system to clear the pathogens.
Define bacteriocidal
causes cell lysis and death of the bacteria

Beta Lactams have what MOA?
They are bacteriocidal . They inhibit cell wall synthesis.
The cell wall is made-up of repeating peptoglycans that are cross linked by proteins. The crosslinking is catalyzed by penicillin binding protein (PBP). Beta lactams inhibit PBP. Therefore, the cell wall becomes unable to deal with osmtic gradients.
Four things occur within the bacteria making them resistant. They are?
The bacteria make betalactamaze.
They change in the binding of PBP so antibiotics can no longer bind.
They decrease penetration of the outer mombrane.
They efflux the drug across the outer membrane.
(the last two only apply to gram neg)
What organism arouse due to changes in PBP?
MSSA became MRSA. MSSA was treated with betalactam until it became resistant. Now MRSA is resistent to all betalactams and most other antimicrobials.
Beta lactam Adverse Reactions
Allergic (pcn): rash, urticaria, anaphylaxis

neutropenia or thrombocytopenia
seizures (imipenem)
interstitial nephritis
Allergic cross reactivity occurs in?
It is related to the spectrum of activity. The closer the spectrum the higher the reactivity.
What are the two main types of antibiotic reactions?
immediate: anaphylaxis, urticaria, hives
delayed: rash (some believe it is ok to trial other beta latams with close supervision)
Natural PCNs and there spectrum of activity
PCN G (IV/IM) and PCN V (Oral)

Gram pos

IM PCN G (AKA. Benzathine) is the drug of choice for what?
drug of choice for shypillis
Name the three penicillinase resistant pcns
IV are Naficillin and Oxacillin

Oral is Dicoxacillian
What is the spectrum of activity of penicillinase-resistent pcns?
Designed to cover staph aureus
Aminopenicillin's spectrum of activity is?
gram pos. with lesser amounts of gram neg
Name two aminopecicillins
Piperacillin is what type of antibiotic and what is it's spectrum of activity?
antipseudomonal pcn

gram pos, with much broader gram negative. obviously good for pseudomonas aeruginosa
Betalactimase combinations have been form. Their spectrum of activity is?
staph aureua, gram neg, anaerobic bacteria.
Cephalosporins all share the same core structure. How is activity altered?
activity is altered by changing the side chain at positon R1 and R2
First generations cehalosporins are have what spectrum of activity?
mainly gram pos
First generation cephalosporins include?
Cefazolin IV
Cephalexin Oral
What is the spectrum of activity of second generation Cephalosporins?
Gram pos with enhanced gram negative.
Name a second generation cephalosporin?
Cefuroxime, oral currently IV formulas are not availible
What is the spectrum of activity of third generation Cephalosporins?
loss of some gram pos, but enhanced gram negative
Name three third generation cephalosporins?
Cefiaxone IV and ceftazidime IV and cefpodoxime Oral
Side effects of Ceftriaxone?
biliary slugishness, use caution in patients with hepatic disfunction
Describe third generation resistence.
Two ways that are allowing for evasion of tx:

extended-spectrum beta lactamase production

Amp C inducible beta lactamase
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