Peds 5 Flashcards
MOA of Vancomycin
Inhibition of cell wall synthesis by directly binding to D-alanyl-D-alanine oligopeptide
Binds directly to peptidoglycan instead of PBP
What type organisms (not specific) does Vancomycin work againse
Only against gram POSITIVE bacteria
Describe Vancomycin’s susceptibility to beta-lactamase
Resistant to beta-lactamase since they are not beta-lactams
Specific organisms that Vanc is used for
MRSA, meningitis (often combined with CTX), MRSA osteomyelitis, staph epidermidis, endocarditis
Common empiric tx of meningitis
Ceftriaxone + Vancomycin
Describe resistance to Vancomycin
Due to modification of D-ala-D-ala binding site within peptidoglycan structure (D-ala replaced with D-lac)
Adverse effects of Vancomycin
Red man syndrome, thrombophlebitis at injection site, ototoxicity, nephrotoxicity, DRESS syndrome
How do you treat Red man syndrome
Anti-histamines (flushing is due to release of histamine)
What is DRESS syndrome
Drug reaction with eosinophilia and systematic symptoms (fever, generalized lymphadenopathy, skin rash)
MOA of Daptomycin
Daptomycin is a cyclic lipopeptide that inserts lipid tail into cell membrane, leading to depolarization of the cell and cell death
What type of organisms (not specific), does Daptomycin work against
Gram positives only (recall that they work via insertion into cell wall and gram positives have thick cell wall)
Uses of Daptomycin (specific)
Vancomycin resistant bug (enterococcus), staph species (MRSA, VRSA, endocarditis)
What disease will Daptomycin NOT work for
Pneumonia (Daptomycin is antagonized by pulmonary surfactant)
Adverse effects of Daptomycin
Myopathy and rhabdomyolysis
Describe MOA of Tetracyclines
o Inhibition of bacterial protein synthesis by binding to and interfering with ribosomes – this inhibits translation
- Bind reversibly to 30S ribosome subunit, inhibiting translation – bacteriostatic
- Only other 30S ribosome binder is Aminoglycoside
What organisms (not specific) do tetracyclines work against
Both gram positive and gram negative
What are tetracyclines used for (specific)
MRSA, Rickettsia, Brucella, Coxiella, Yersinia, Chlamydia, Mycoplasma pneumonia, Acne
Adverse effects of Tetracyclines
♣ Tooth discoloration in children ♣ Teratogenic (bone deformation) ♣ GI side effects (N/V/D) ♣ Photosensitivity ♣ Fanconi Syndrome – Type II renal tubular acidosis caused by administration of expired Tetracyclines
Describe resistance to Tetracyclines
- Production of efflux pumps to move the drug out of bacterial cell
- Alteration of ribosome
What type of drug is Azithromycin
Macrolide
MOA of Macrolides
Interferes with 50S ribosome – inhibiting translocation
Uses of Macrolides
- Bordatella pertussis
- Community acquired pneumonia caused by Strep Pneumo, H. flu, Moraxella
- Atypical pneumonia caused by Mycoplasma, Legionella, Chlamydia
- Urethritis and cervicitis caused by Chlamydia and Gonorrhea
- Bartonella
- Diptheria
- Mycobacterium Avium
- H. Pylori
Adverse effects of Macrolides
- Increased GI motility
- Acute cholestatic hepatitis
- Prolonged QT (torsades)
MOA of Clindamycin
♣ Inhibits 50S ribosome, blocking translocation and protein synthesis – bacteriostatic
What broad categories of organisms are treated by Clindamycin
Gram positives, Anaerobes
What is the general rule of thumb for treatment of anaerobes
Clindamycin treats anaerobic infections above the diaphragm and Metronidazole treats anaerobic infections below the diaphragm
What type of gram positives does Clindamycin treat
- Strep pyogenes (skin and soft tissue infection)
- MRSA
What type of anaerobic infections does Clindamycin treat
- Lung abscesses
- Aspiration pnemonia (e.g. Bacteroides fragilis)
- Clostridium perfringens
- Moderate to severe inflammatory acnes
- Endometritis caused by retained products of conception, septic abortion, abscess, or foreign body (not caused by Chlamydia or Gonorrhea)
- Bacterial vaginosis caused by Gardnerella vaginalis
Adverse effects of Clindamycin
Diarrhea, pseudomembranous colitis
What is rickets/osteomalacia
♣ Defective mineralization of osteoid
• Osteoblasts still produce osteoid, but it cannot be mineralized with Ca2+ and phosphate to form bone
♣ Due to Vitamin D deficiency, which causes low calcium and phosphate
• Deficiency can be due to poor diet, decreased sun exposure, malabsorption, renal failure, liver failure
Describe net effect of PTH on bones
New effect of bone resorption/breakdwin = increases calcium
Describe effects of PTH on the kidney
- Increases calcium reabsorption
- Decreases phosphate reabsorption
- Increases production of Vitamin D activating enzyme
Effects of vitamin D on the kidney
- Increases reabsorption of Calcium AND phosphate
Effects of vitamin D on intestines
Increases absorption of calcium AND phosphate
Effects of Vitamin D on bone
Increases bone turnover (both osteoclasts and osteoblasts)
Describe effects of Vitamin D on PTH
Negative feedback - inhibits PTH production by the parathyroud gland
How can biliary atresia lead to rickets?
Lack of bile salts = no absorption of fat-soluble vitamins (ADEK) = low vitamin D
What is Kasai procedure
An operation to correct biliary atresia - bowel loop forms a duct to allow bile to drain from liver with biliary atresia
Describe labs in Vitamin D deficiency:
- Calcium
- Phosphate
- PTH
- Alkaline phosphatase
- Decreased Ca2+
- Increased PTH
- Decreased phosphate
- Increased alkaline phosphatase (hyperactivity of osteoblasts)
Tx of Vitamin D deficiency in the following age groups:
- < 1 mont
- 1-12 months
- > 12 months
< 1 month = 100 IU Vitamin D daily
1-12 = 1000-2000 IU
> 12 = 2000 IU
How much Vitamin D should be given as supplement in infants and children
< 12 months = 400 IU
1-18 years = 600 IU
What is vaso-occlusive crisis
Episode of severe pain caused by increased sickling of RBCs, which leads to bone marrow ischemia and infarction
What is dactyltitis
A form of vaso-occlusive crisis that involves painful swelling of hands and/or feet
What is acute chest syndrome
A new pulmonary infiltration on chest x-ray in addition to one of the following signs: fever, chest pain, SOB, tachypnea, or low O2 sats
What is aplastic anemia
Caused by Parvovirus B19 infection in sickle cell patients. Causes depletion of bone marrow, leading to cessation of RBC formation. Reduced lifespan of RBCs in SCD coupled with reduced production can result in profound anemia
Tx of vaso-occlusive crisis
IV fluids and pain management (e.g. narcotics)
Tx of acute chest syndrome
Empiric abx, supplemental O2, pain meds, and IVF
Long term tx of recurrent sickle cell crisis
Hydroxyurea will increase the concentration of fetal hemoglobin, thus reducing the frequency of sickle cell crisis episodes
Why should transcranial doppler US be performed annually in sickle cell patients
To monitor for signs of stroke
Causes of unilateral kidney masses
- Multicystic, dysplastic kidney
- Hydronephrosis
- Renal vein thrombosis
- Mesoblastic nephroma
- Wilms Tumor
Causes of red urine with no RBCs
Myoglobinuria!
Beets, Rifampin, Blackberries, porphyrin
