1. Human nasopharynx is a reservoir for neisseria meningitis; use droplet precautions.
2. PPD skin test cutoffs for TB
- 5: HIV, transplant, immunosuppressed (ie. lupus, >15mg/day of prednisone for >1mo). Close contact with TB+ person. Suspicious CXR (c/w prior TB)
- 10: Recent immigrants (<5 yrs) from high prevalence countries, IV drug users, people close to jails, homeless shelters, hospitals, kids < 4 years old, kids exposed to high risk adults, some chronic diseases (DM, renal failure, some cancers like leuk, lymph, head+neck, lung, silicosis, gastrectomy, some GI bypass procedures)
3. TB: 
- BCG vaccine induced false-positive PPDs should fade after 10 years, so anyone >10 years out should be treated like anyone else and the tests interpreted accordingly.
- Exposure in the distant past may lead to a false neg PPD; repeat testing in 1-3 weeks may reveal a positive test. Indicated in older people, people who may have had a distant exposure
- B6: 2% of people develop peripheral neuropathy on isoniazid without B6. People at esp high risk for neuropathy: diabetes, uremia, alcoholism, malnutrition, pregnancy, HIV, seizure disorders.
- Screen for latent TB before getting solid organ transplant, starting chemo, or starting TNF-a inhibitor (infliximab, adalimumab, etanercept). Any PPD >5 qualifies as + in these people (regardless of their other risk factors) and should get 6-9 months of INH + B6. You can probably start the TNF-a inh 2 months into INH therapy but this is a matter of debate.
4. Severe CAP
- Pseudomonas risk factors: bronchiectasis, recent (<1 month) steroid/broad spectrum antibiotic use, malnutrition.
- MRSA risk factors: severe, rapidly progressive course, infection during flu season, cavitary infiltrates on CXR, history of MRSA
5. Legionella
- Risk factors: smoking, DM, HIV, CKD, liquid and solid tumors.
- Often presents with high fevers, hyponatremia, GI sx,
- Urine legionella test: 70-90% sens and 99% spec for L. pneumophila serogroup 1-- doesn't detect other serogroups. Neg test does not r/o. Test will be pos day 1 of infection and remain + for weeks.
- Blood and thora cx will not grow + cultures so don't bother
6. CKD + immunity
- Uremia causes an immunocompromised state
- CKD associated with dysfunction in innate and adaptive immunity, TLR, etc
7. Erythromycin does not cover h.flu.
8. Criteria for antibiotic prophylaxis before dental procedures: 
- Prosthetic valve
- History of infective endocarditis
- Congenital heart disease that is unrepaired/not fully repaired or has been repaired within last 6 mos
- S/p heart transplant with valve disease
9. Antibiotic prophylaxis before dental procedure:
- Cover for strep viridians
- PO amox
- IV amp, cefazolin, ceftriaxone for people who can't take PO
- Clinda, azithro, clarithro for people who are pen allergic
- Take 30-60 mins before procedure
10. Injection drug user, multifocal pneumonia, heart murmur:
- Think septic emboli from tricuspid valve endocarditis
- Usually s.aureus, cover MRSA, pseudomonas until cx come back proving they're not present.