ANTIBIOTIC THERAPY
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PRINCIPLES OF EMPIRIC ANTIMICROBIAL THERAPY
Decision making process in which clinician
chooses agent based on characteristics and site of
infection
What is/are the most common likely pathogen(s)
causing this infection?
What bug will this antibiotic kill?
Likelihood of resistant pathogen?
Danger if treatment failure?
What is optimal safe dose?
What duration is shortest but effective?
TETRACYCLINE
Gram -; Atypicals; MRSA
Do not use in pregnancy or children < age 9
May cause permanent discoloration of teeth and
skeletal defects if used in last half of pregnancy
Treat for acne age 13-14 as all teeth have erupted
o Do not use for mild comedones – start
with OTC topicals such as salicylic acid and
benzoyl peroxide
o Try RX topicals benzamycin, Retin A and
azelaic acid cream first for 2-3 months
Photosensitivity
Esophageal ulcerations (swallow with full glass of
water)
Take on empty stomach
May decrease effectiveness of birth control pills
 Throw away expired pills – they degenerate and
may cause nephropathy
LINCOSAMIDE - CLINDAMYCIN
Gram +, Aerobes, Anaerobes
Associated with C. Diff
ANTIBIOTICS
GRAM POSITIVE
 Strep
 Staph
 Enterococcus
GRAM NEGATIVE
 H. influenzae
o Cephalosporin, Augmentin, macrolides,
resp. fluoroquinolones, doxycycline
 Everything else
MACROLIDES
Atypical pathogens
 Associated with potential QT prolongation and ↑
risk of CV death
Contraindicated in myasthenia gravis
Drug-drug interactions (anticoagulants, digoxin,
theophylline, select statins)
Erythromycin GI side effects are common
Macrolide allergic: doxycycline, quinolones
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CEPHALOSPORIN
1 generation: Gram +; Beta-lactam; Cephalexin,
Cefadroxil Group A Strep, S. aureus – not MRSA –
Keflex (pregnancy UTI, cellulitis, impetigo)
2nd generation: Gram +/- Broad spectrum –
Ceftin, Cefzil – otitis media, rhinosinusitis, CAP,
chronic bronchitis
3rd generation: Gram – with weak Gram +; Betalactam; Cefixime
Extended 3rd generation: Gram +/-; Beta-lactam;
Rocephin, Cefdinir – gonorrhea, PID,
pyelonephritis, otitis media
Cross reactivity between PCN and cephalosporin
usually occurs with 1st generation
st
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RISK FOR ANTIBIOTIC RESISTANCE
Age <2 or >65
Antibiotic use within the last month
o 3 months for pneumonia
Hospitalization within 5 days
Comorbidities
Immunocompromised
PENICILLIN
Diarrhea, C. Diff, Vaginitis, StevensJohnson syndrome
Avoid amoxicillin for patients with
mono (generalized rash)
Dicloxacillin – mastitis & impetigo
Anaphylaxis and angioedema are type
1 IgE
PCN allergic: macrolides
AUGMENTIN
Gram +/-, beta-lactamase. NO MRSA
High-dose 3-4g/day amoxicillin needed
for drug-resistant Strep pneumoniae
(DRSP)
Clavulanate as beta-lactamase
inhibitor so amoxicillin can work on H.
influenzae, M. catarrhalis
FLUOROQUINOLONES
 Cipro: Gram -; atypical pathogens
 Levaquin: Gram +/-; Atypical, DRSP
 Achilles Tendon rupture (esp. with
steroid use
 Contraindicated – less than 18,
pregnancy, breast feeding,
myasthenia gravis
 QT prolongation, hypoglycemia
ANTIBIOTIC THERAPY
SULFONAMIDE
Gram -; MRSA; NO STREP, NO E COLI
Contraindications
o G6PD anemia causes hemolysis
o Newborns and infants < 2 months
HIV patients are high risk for Stevens-Johnson
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MEDICATIONS THAT REQUIRE EYE EXAM
Digoxin (yellow to green, blurred vision, halos if
blood level too high)
Ethambutol and linezolid (optic neuropathy)
Corticosteroids (cataracts, glaucoma, optic
neuritis)
Fluoroquinolones (retinal detachment)
Viagra, Cialis, Levitra (cataracts, blurred vision,
ischemic optic neuropathy, others)
Accutane (cataracts, decreased night vision)
Topamax (acute angle-closure glaucoma,
increased intracranial pressure, mydriasis)
Plaquenil (neuropathy and permanent loss of
vision)
SOUTHEAST ASIAN CULTURE
Vietnamese, Hmong, Filipinos
Pt may have difficulty verbalizing questions about
treatment
May consult family about major health decisions
Will not tell provider if not compliant
Would never verbalize disagreement in loud
voice – have high regard for physicians
Imbalance of hot and cold (yin/yang)
Male is head of house
Alpha thalassemia is common in Asians, Filipino
View surgery as last resort
Infants and small children may wear amulet
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BETA-LACTAMS
Penicillin – Penicillin, Amoxicillin, dicloxacillin,
ampicillin and others
Cephalosporin – ceph- or cef- prefix
Carbapenem – imipenem usually given with
cilastatin
Monobactam – aztreonam
High rate of allergic reactions
NITROFURANTOIN
 Urinary pathogens
METRONIDAZOLE (FLAGYL)
RANDOM HERB FACTS
 Echinacea – immunological effects
 Black cohosh, roasted soy beans – acts
similar to estrogen for some people
 Kava Kava - anxiety
 St John’s wort – depression
o interacts with oral
contraceptives, cyclosporine
and select antiretrovirals
 Saw Palmetto – BPH
 Fish oil and ginseng can cause bleeding
 Milk thistle – lower cholesterol, liver
problems and diabetes
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 Anaerobes
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FOOD FACTS
 Tetracycline and dairy interact
 Avoid MAOI and high tyramine containing foods
(fermented foods)
 Eat salmon and omega-3 for heart disease; plant
sterols and stanols reduce cholesterol
 Collard greens are high in vitamin K
 Magnesium - decreases BP and dilates blood
vessels (nuts, beans, wheat, laxatives)
 Potassium – decreases BP – most fruits, leafy
greens and nuts
 Non-dairy calcium includes: tofu, spinach and
sardines
 Celiac Disease - Avoid gluten, wheat, rye, barley,
oats. Gluten free foods: corn, rice, potato, quinoa,
tapioca, soybeans
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VITAMIN D DEFICIENCY
Vitamin D inhibits abnormal cellular
growth; encourages reabsorption and
metabolism of calcium and phosphorus;
reduces inflammation
Skin exposure to sun produces greatest
values
Someone taking phenytoin needs 2-5x
vitamin D
Symptoms of vitamin d deficiency
o Rickets, osteomalacia, antigravity
muscle weakness
25-hydroxyvitamin D is lab measurement
A child must drink 32 oz of milk daily to
receive recommended 400 IU (infants) of
daily vitamin D
600 IU for those age 1-70 including
pregnant; 800 IU > 70
Darker skin tones synthesize less vitamin D
Sunscreen increase risk of vitamin d
deficiency
Vitamin d deficiency is common in hepatic,
renal and after gastric bypass.
Vitamin D3 is preferred form
o 50,000 IU per week x 8 weeks
o 1000-2000 daily