Antibiotics Flashcards
What makes mycobacterial infections like TB difficult to treat?
Slow-growing and resistant microbes - require prolonged treatment
Tuberculosis
Treatment regimen
Determine drug sensitivty
At least 2 drugs
6 month course for active TB
TB
Diagnosis
Chest x-ray
Sputum culture
Why is active TB treated with multiple antibiotics?
Some infecting bacilli are inherently resistant
How do you test for latent TB?
-TB skin test (PPD test)
-QuantiFERON-TB blood test
Standard treatment for latent TB
Isoniazid
Isoniazid
Uses
-Part of combo therapy for active TB
-Latent TB
Isoniazid
Adverse effects
Risk of liver damage
Neuropathy (tx is Vit B6 pyroxidine)
Optic neuritis (inflammation of optic nerve)
Pyrazinamide
Ethambutol
Use
Antituberculosis drugs
(active TB)
Rifampin
Use
Broad spectrum antibiotic
TB
Rifampin
Adverse effects
-Liver damage
-Discoloration of body fluids (turns body fluids red) - not serious
Pyrazinamide
Use
Active TB
Pyrazinamide
Adverse effects
Liver damage
Ethambutol
Use
Active TB
Ethambutol
Adverse effect
Optic neuritis
Penicillin
Family
Beta-lactam
What antibiotics are in the beta-lactam family?
-cillins
-Cephalosporins
-Carbapenems (Imipenem)
Penicillin
Main adverse effect
Low toxicity, main adverse effect is allergic reaction
Penicillin
Mechanism of action
Weaken the cell wall, causing bacteria to take up excessive water and rupture
Beta-lactamase (e.g. penicillinase)
Mechanism of bacterial resistance where bacterial enzymes inactivate penicillin
Penicillin is active against gram ______ bacteria
positive
Gram negative bacteria have an extra ____ that make it difficult for antibiotics to penetrate
envelope / membrane
Penicillin and Nafcillin are ____ spectrum antibiotics
narrow
Ampicillin (Principen) and amoxicillin (Amoxil) are _____ spectrum penicillin
Broad
Piperacillin/tazobactam is a _____ spectrum penicillin
extended
Penicillin G (Benzylpenicillin)
Use
-Strep
-Kills a number of gram-positive organisms and some gram-negative organisms
Penicillinase-Resistant Penicillins effective against most Staph (but NOT MRSA)
Nafcillin
Oxacillin
Dicloxacillin
Broad-spectrum Penicillin
(Ampicillin, Amoxicillin)
Adverse effects
Rash
Diarrhea
What does the Tazobactam in piperacillin/tazobactam do?
Beta lactamase inhibitor
Clavulanic acid
Class
Beta-lactamase inhibitor
What antibiotic can be prescribed if patient has mild penicillin allergy?
Cephalosporin
Can you prescribe cephalosporin in a patient with history of anaphylaxis from penicillin?
NO (only in mild allergy)
Anaphylaxis
Signs and symptoms
Severe hypotension
Systemic hives (urticaria)
Laryngeal edema
Wheezing
Fluoroquinolones
Use
Broad spectrum agents
Fluoroquinolones
Route
IV
PO
Fluoroquinolones
Mechanism
Disrupt replication and cell division
Fluoroquinolones
Adverse effects
Can cause tendon rupture (low risk) - usually affects Achilles tendon
Who is at greatest risk of tendon rupture from fluroquinolones?
-Patients older than 60
-Patients taking glucocorticoids
Fluoroquinolones
end in -
Floxacin
Ciprofloxacin
Class
Fluoroquinolone
Ciprofloxacin
Uses
BROAD SPECTRUM
Ex: anthrax, respiratory, UTI, GI, bones, joints, skin, soft tissue
Ciprofloxacin
Adverse effects
CNS: dizziness, headache, restlessness, confusion
Tendon rupture
Increased risk of C. Diff
Ciprofloxacin
Interactions
-Food/drugs that have ionic compounds / salts
-Absorption reduced by antacids
-Milk and dairy products
-Can elevate levels of other drugs
Metronidazole [Flagyl]
Uses
C. diff
Anaerobes
Protozoal infections (e.g. Giardia)
Metronidazole [Flagyl]
Interaction
Antabuse-type reaction
What antibiotics have cross-reactivity with penicillin?
Cephalosporin
Carbapenem
Cephalosporin
Class
beta-lactam antibiotics (like penicillin)
Cephalosporin abx have what in their name?
Prefix of ceph or cef
Cephalosporin
Toxicity
Like penicillin, toxicity is low
Cephalosporin
Route
Usually IV
Also available PO
Cephalosporin
Mechanism
Bind to penicillin-binding proteins disrupt wall synthesis and cause cell lysis
How do drugs grow resistance towards Cephalosporin?
Beta-lactamases (cephalosporinases)
1st generation Cephalosporin are commonly used for _____ in the hospital
prophylaxis
Advantages to later generations of Cephalosporin
(like 3rd on)
-Broader spectrum
-Can kill more gram negative bacteria
-Can kill Bacteria that make beta-lactamase
-at 3rd generation - can penetrate blood brain barrier like meningitis
Which cephalosporin is active against MRSA?
5th generation
Ceftaroline
What can 4th generation cephalosporin kill that earlier generations cannot?
Pseudomonas
Cefotetan (a cephalosporin)
Interactions
-Combination with alcohol causes antabuse-like reaction
-Warfarin (increased risk for serious bleeding)
Celphalosporin
Adverse effects
Allergy
Thrombophlebitis
Carbapenems (e.g. Imipenem [Primaxin])
Spectrum
Extremely broad spectrum
Carbapenems
(e.g. Imipenem [Primaxin])
Use
Severe, hard to treat infections
but NOT MRSA
Vancomycin
Spectrum
Narrow spectrum
Only gram-positive bacteria (e.g. staph, strep)
Vancomycin
Uses
Severe infections (IV)
Pts with penicillin allergy
MRSA (IV only)
C. Diff (PO)
Vancomycin
Adverse effects
-Nephrotoxicity
-Ototoxicity
-Thrombophlebitis
-“Red” syndrome - caused by histamine release when a pt takes too much too fast - signs are fever, tachycardia, itchiness (but no wheezing, or hypotension) - can treat with antihistamine
