Lecture 1: Antibiotic choices in primary care Flashcards
Which bacteria are gram positive?
Strep pneumoniae (aka Pneumococcus) Strep group A beta hemolyticus (aka Strep pyogenes) Staph aureus (MSSA, MSRA)
Which bacteria are gram negative?
Hemophylus influenza (H.flu) Pseudomonas E.coli Proteus Klebsiella
Which bacteria are atypical?
Mycoplasma Chlamydia pneumoniae (C. pneumoniae)
What characteristics are unique to gram positive bacteria?
thick wall (that can be stained)
What characteristics are unique to gram negative bacteria?
thin wall (can be stained) mostly bacteria that live in colon- except H. influenza (lives in nasopharynx) and pseudomonas (skin “bully”- attacks weak, immunocompromised/ anatomical problems- never attacks normal, healthy patients)
What characteristics are unique atypical bacteria?
no walls (cannot be stained). Intracellular organisms; they can be atypical regardless of presentation of illness- just depends on the bacteria causing illness.
What bacteria will cause pharyngitis?
Strep group A beta hemolyticus (aka streptococcus pyogenes)
What bacteria will cause otitis media and sinusitis and pneumonia?
Strep pneumoniae (aka pneumococcus) or H. Influenzae (they are BFF) so when treating these things, you need coverage for both gram +/-
What things can be caused by strep group A/ strep pyogenes?
strep pharyngitis, skin infections, rheumatic fever and post-streptococcal glomerulonephritis
What other things can be caused by strep Pneumoniae?
pneumonia and meningitis
Why do we treat strep pharyngitis?
to prevent rheumatic fever
Strep pneumoniae causes?
sinusitis, otitis and pneumonia BUT NOT pharyngitis
How does rheumatic fever occur?
antibodies that were produced to kill strep pyogenes will also attack proteins in the heart because they are structurally similar and cause RF. Antibody- mediated reaction
strep pyogenes also causes what (other than pharyngitis) that can lead to what?
skin infections that can lead to post-streptococcal glomerulonephritis (abx will not reduce risk of getting this)
What is the most common bacteria that causes pneumonia?
Strep pneumoniae
Which bacteria causes pneumonia?
strep pneumoniae (gram +) H. flu (gram -) mycoplasma (atypical) chlamydia pneumonae (atypical) *so when treating PNA, need to cover for all 3 groups
What is #1 cause of death in US in terms of infectious diseases?
pneumonia
strep pneumoccocal vaccine good at protecting against what? and not good at protecting against what?
good for preventing invasive disease (bacteria that spread to places it isn’t in normally like meninges or blood) but not too good at preventing non invasive disease like sinusitis, otitis
skin infections only caused by what type of bacteria?
gram positive
With skin infections, what is the difference between Strep. spp (group A, B) and Staph spp ( MSSA, MRSA)?
strep is non- purulent, MRSA is purulent
What infections can be caused by Strep. spp (group A, B) or Staph spp ( MSSA, MRSA)?
Skin infections Osteomyelitis Septic joint Endocarditis Otitis externa Conjunctivitis
Otitis externa ( in swimmers) and conjunctivitis (in contact lenses wearers) are also associated with what bacteria?
Pseudomonas- the bully that loves water
bacteria found in the colon include?
E.coli
Proteus
Klebsiella
these bacteria (E.coli, Proteus, Klebsiella) cause what infections?
Cystitis Pyelonephritis Prostatitis Diverticulitis Cholecystitis Cholangitis
What antibiotic is most narrow and covers only strep pyogenes?
PCN
This antibiotic covers strep pyogenes and some strains of gram negatives- E. Coli , Proteus, and H. flu
Amoxicillin (can be used for UTI in pregnant women and also for children with otitis media because it covers for h. flu)
side effects of PCN/ amoxil?
rash and diarrhea
Can PCN/ amoxil can be given in pregnant women, lactating women and children?
yes
Amoxicillin w/ clavulanate covers what?
Gr+ (only Strep) , Gr– (H.flu, Moraxella)
What is the major advantage of cephalosporins?
in addition to strep, they also cover staph. (but they do NOT cover MRSA)
Good abx choice for skin infection without purulent drainage?
Keflex (cephalosproin) (only non purulent because doesn’t cover MRSA)
2nd or 3rd generation cephalosporins also cover what in addition to staph & strep?
Gram negatives, may be good option for otitis media or sinusitis
The major side effect of cephalosporins?
rash and diarrhea
Who can/ can’t be prescribes cephalosporins?
Good for children, pregnant women, people who have mild allergy to PCN (depending on the reaction- if only rash, can give). Not good for pts who have anaphylactic rxns to PCN.
What covers MRSA?
Bactrim
Clina
Doxy
“MRSA” - “BC & D”
Can you give bactrim to pregnant women?
No. Because it is a folate antagonist
What does clinda cover?
Only Gr+ (Strep and Staph). Covers MRSA, but not reliable strep coverage
What does doxy cover?
Broad coverage (Gr+, Gr-, atypical). Covers MRSA but unreliable coverage against Gr – and Strep
What does Bactrim cover?
Gr+ (including MRSA), Gr- but unreliable coverage against Gr- and Strep
Major doxy side effect?
Photosensitivity
Doxy ok for pregnant women, breast feeding women, or children under 8 years old?
No- effects teeth development
What do macrolides will cover what bacteria?
Broad coverage (Gr+, Gr-, atypical) covers
Major side effect of macrolides?
Diarrhea
Who id OK to be prescribed macrolides and who is not?
OK for children and pregnant women, not good in people with arrythmias- will cause multifocal ventricular tachycardia/ torsides de point- they prolong QT
which classes of abx prolong QT?
macrolides and fluroquinolones- widest coverage= prolonged QT
If patient is on these type of meds, you will not give macrolides or FQ
antiarrthymics and antipsychotics- all prolong QT
FQ ok to give to children or pregnant women?
No- affects bone development “fluroquinobones”
Respiratory FQ (levo-, moxi) cover what bacteria?
Broad coverage (Gr+, Gr-, atypical)- wide coverage
Non-respiratory FQ (cipro-) cover what?
Mostly Gr – ;also covers Pseudomonas
Amoxicillin w/ clavulanate will cover what?
Gr+ (only Strep) , Gr– (H.flu, Moraxella)- better coverage for H. flu than amoxil
What is different about viral pharyngitis?
viral- always involves at least 2 mucous membranes involved (cough, nasal discharge, fever, conjunctivitis, etc.)
What will be different in peritonsilar abcess?
“hot potato voice,” pushes uvula to normal/ unaffected side of pharynx), drooling because inability to open mouth & trismus- unable to open mouth
What will be different in mononucleosis?
pt will develop myalgia 1st- before sore throat. Also posterior cervical lymphadenopathy and abdominal pain because of enlarged spleen. This virus is never cleared, stays latent in body like herpes, varicella. Epstein barr virus associated with Hodgkins lymphoma
What will be different in bacterial pharyngitis? How do you diagnose?
1 mucous membrane involved, high fever, exudate, anterior lymphadenopathy. It is NOT clinical diagnosis, need positive rapid antigen test to dx/ prescribe meds
Who can get a rapid strep test?
need to follow Centor criteria:
tonsilar exudate +1
tendor anterior cervical lymphadenopathy +1
fever +1
absence of cough +1
<15 years +1
- need at least 2 of these criteria to do a rapid strep test
What kind of blood work results would you expect in mono? Is this diagnostic?
Not diagnostic- only supports your diagnosis. You will see elevated WBC’s- predominantly lymphocytosis, atypical lymphocytes on a blood smear, and elevated liver enzymes (self- limiting)
If you suspect mono- what test should you order for diagnosis? If negative?
monospot. If negative repeat monospot or do serum serology for Igm (immediate). Also could order labs to support diagnosis (CBC, LFT’s, blood smear)
If you suspect peritonsilar abscess what should you order? How do you diagnosis it?
Diagnosis is clinical but need to order CT to see if it’s only cellulitis or if there is also an abscess inside that needs to be drained
When to order IV contrast vs no contrast CT?
if suspect infection/ abscess or tumor- need contrast so you can see blood vessels. If you do not suspect these no need for contrast.
+ rapid strep test, treat with what?
PCN, only need narrow coverage. Can give amoxicillin to kids because it tastes better.
+ mono spot, treat with what?
supportive therapy, need to make sure spleen doesn’t rupture- no sports 4 weeks after onset
How do you treat a peritonsilar abscess?
drain it if needed, and antibiotics (amoxil or clinda)- but should send to hospital
How do you diagnose bacterial rhino sinusitis? What is different about it?
clinically; do not need any tests. Will have unilateral discharge, high fever
What is different about allergic rhinitis?
itchiness major symptom, discharge always bilateral and clear
If a patient has recurrent sinusitis/ is unresponsive to treatment what should you do?
CT with contrast to r/o obstruction- if none then do a culture from sinus aspirate (most accurate test for all infectious diseases)
What are the rules on when to treat sinusitis?
Treat when:
- pt has severe sx for 3 consecutive days without improvement OR
- sx prolonged (may not be so severe) but prolonged for 10 days OR
- double sickening aka it was bad, it got better, then it got worse again
How would you treat sinusitis?
Augmentin (since it could be H. flu or strep pneumoniae so need coverage for gram +/-) If pt has an allergy, levofloxacin (respiratory FQ)
How would you treat allergic rhinitis?
nasal corticosteroids (most effective therapy) but to help with blockage, add decongestants, to help with discharge add antihistamines
When do you treat otitis media?
It is a clinical diagnosis- to treat you need both TM effusion and s/s of inflammation-
- TM effusion (shown by bulging and/ or non moveable, - TM inflammation (shown by pain and fever)
How will otitis media with effusion present?
fluid but no infection. hearing loss but NO pain, NO fever
What is malignant otitis externa?
bacteria spread to the bone- actually osteo- common in patients with diabetes or if they are immunocompromised
When should you do Rinne/ Weber tests?
Only if patient is complaining of hearing loss- these are not screening tests to do on everyone. If you note conductive hearing loss on Weber, then do Rinne next to confirm.
Explain Weber.
Normal response is to hear sound equally in both ears. If patient has conductive hearing loss, pt will hear better in affected ear aka the sound will lateralize/ be louder to the side WITH conductive hearing loss. If pt has sensorineural loss the affected side will not be working at all- so the pt will hear better in the normal side/ unaffected side.
Explain Rinne.
Normally- air conduction longer than bone conduction but if there is conduction hearing loss, it won’t be longer than bone. Bone conduction will be longer than air on side of affected ear. It CONFIRMS conductive hearing loss if established with Weber
