Infectious Diseases

  1. Antibiotics
  2. CNS Infections
  3. Head and Neck Infections
  4. Lung Infections
  5. GI Infections
  6. Viral Hepatitis
  7. Sexually Transmitted Infections
  8. Urinary Tract Infections
  9. Skin Infections
  10. Bone Infections
  11. Endocarditis
  12. Lyme Disease
  13. AIDS

ANTIBIOTICS

Staph and strep infections rx w ox, clox, diclox, and naf. If get rash w these, rx w 1st gen cephalosporins. If get anaphylactic rxns from penicillins, rx w non beta lactams. Instead, if infection mild, use macrolide or clindamycin (rx staph, strep, anaerobes).

4 types of beta lactams: penicillins, cephalosporins, carbapenems, and sulbactam. Pen and ceph have less than 10% cross reactivity. Pen and carbapenems have less than 1%. Pen and monobactam (Aztreonam) have 0% cross rxn but monobactam only can rx gram neg, so can’t use for staph or strep.

Don’t use methicillin bc have renal toxicity. Instead use related penicillins like ox, clox, diclox, and naf.

Strep mutans and viridans only in endocarditis.

Rx MRSA w vancomycin, linezolid, dapromycin, or tigecyclin (rx gram neg, anaerobes, and MRSA)

G neg rods cause pyelonephritis, peritonitis, ascending cholangitis, cholecystitis. Rx G neg w aminoglycosides, carbapenems, aztreonam, fluroquinolones, 3/4 gen ceph (cephtazidine, cefepine), anti-pseudomonas penicillins (pipercillin, ticarcillin). All cover 80-90% of all G neg rods.

Respiratory anaerobes infection rx w Clindamycin.
GI anaerobes infection rx w metronidazole (c diff)

Doxycycline rx chlamydia, rickettsia, early Lyme disease.

TMP/Sulfa (Bactrim) rx PCP and uncomplicated cystitis.

Ampicillin + sulbactam
Amoxicillin + Clavulanic acid
Piperacillin + Tazobactam
Adds staph coverage and extends g neg coverage.

Oseltamivir, Zanamivir – rx Influenza
RitonAvir, IndinAvir, SaquinAvir — rx AIDS (protease inh)
AcyclOvir, GanciclOvir, ValacyclOvir — rx Oh sh*t I got herpes.

CENTRAL NERVOUS SYSTEM DISEASES

Meningitis, encephalitis, abscess all can cause headache and seizure.
Meningitis also stiff neck, photophobia
Encephalitis also confusion (bc is inflamed brain)
Abscess also focal neurological findings

Do CT scan before lumbar puncture when see confusion, focal neuro damage, papilledema bc these may be due to high intracranial pressure, in which LP may be contraindicated. Do LP before give empirical antibiotics bc will change csf culture results. All others just do lumbar puncture to test CSF for protein (elevated in meningitis), glucose (low), PMN count (high). Cell culture is most accurate but takes too long (3 days). Testing for glucose and protein levels is not specific or accurate. Bact decr glucose. Bact, virus, and all incr protein. Therefore test for WBC count.

If see 1000s of PMNs, then is bacterial meningitis. Rx bacterial meningitis w ceftriaxone and vancomycin. Add steroids if acute bacterial and TB meningitis to relieve inflammation. Intravenous, never intrathecal, bc RIPES cross bbb.

Most common meningitis in adolescents is neisseria, bc kiss a lot and spread thru salivary contact. Also isolate pt and give close contacts (salivary or home contacts) rifampin and ciprofloxacin (on top of ceftriaxone and vancomycin).

If see 10-100 Lymphocytes (and neg gram stain, no bact culture etc), then could be cryptococcal, Lyme, RMSF, TB, or viral meningitis.

If have meningitis, AIDS, and low T cells, suspect cryptococcal neoformans. best initial test is India Ink but most accurate test is Cryptococcal antigen test. If positive, rx w amphotericin and flucytosine, followed by fluconazole. Stay on fluconazole life long unless T cells go up.

When u treat an infection, antigen levels change, but antibodies dont.

Lyme disease and RMSF both from ticks, camping etc. but Lyme has bulls eye rash and RMSF rash start in limbs and move centrally.

TB meningitis you most likely see high protein level in csf. Rx like TB lung w RIPES but also add steroid for TB meningitis to rx inflammation.

Don’t delay treatment of meningitis! go ahead and treat patient w ceftriaxone and vancomycin before do CT or lumbar puncture. Do CT if pt has other suspicious signs like arm or leg weakness.

If meningitis is recurrent or pt has leukemia, lymphoma, HIV, elderly, neonate, or on steroids, then pt may have listeria (have risk factors). Rx w ampicillin bc listeria intrinsically resistant to all cephalosporins.

Acute fever and confusion suggests herpes encephalitis. Do CT of brain. But best diagnostic test is PCR. Much better than brain biopsy. Rx Acyclovir.

If had fever, headache, in HIV pt, and see ring enhancing lesion on Head CT, suspect toxoplasma or lymphoma. rx w pyrimethamine and sulfadiazine (or clindamycin if allergic to sulfa). Do head CT in 2 wks again. If lesion smaller then u know it is toxoplasma. If not, then do biopsy. If see ring enhancing lesion in HIV negative pt, then go straight to biopsy bc unlikely toxoplasma.

Most common cause of meningitis is strep pneumo, neisseria meningidites, and haemophilus influenza. Neisseria and Hib are both Gram negative, and are treated w ceftriaxone, which rx both Gram neg and pos. Strep pneumo is gram positive and is treated with vancomycin, which rx gram pos only. Strep pneumo used to be suseptible w ceftriaxone, penicillin, etc but most have gained resistance, so therefore vanco is used nowadays. However if you find out that the pneumococcus is beta lactam sensitive, then discontinue vanco bc ceftriaxone will be enough.

HEAD AND NECK

Sinusitis and otitis media have same etiology.
Caused by strep pneumo, h. Influenza, and moraxella.

Otitis media you have immobility of the tympanic membrane (bulgy)
Best initial test for sinusitis is CT, XR, but u only can tell u have sinusitis, but not which organism. most accurate test is sinus aspirate and biopsy, then culture.

Best initial therapy for Otitis and sinusitis is amoxicillin bc cheapest and just as effective as all the other drugs. But if there is resistance to amoxicillin, rx w 3rd generation cephalosporin.
Azithromycin and clindamycin covers atypical bacterial causes. Atypical means u can’t stain it or it doesn’t show up on cultures
Fluoroquinolones best for penicillin-resistant pneumococcus (VRSE). Most of time use this in recurrent sinusitis, which often is penicillin resistant.
Although different drugs have different ranges of treatment, they all have same efficacy. Most otitis media resolves spontaneously without treatment.

Pharyngitis has sore throat, positive nodes, exudate (white at back of throat). No hoarseness or cough. Hoarseness is laryngitis. If no exudate, then viral cause.

Strep pharyngitis (strep throat) can cause glomerulonephritis and rheumatic fever.
Strep skin rash (scarlet fever) can cause glomerulonephritis only.

Rapid strep test just as accurate as culture. Positive is always positive. Negative is negative in adult, but not necessarily in children.

Fever, myalgia, headache, aches, sore throat, cough — influenza. Rx w oseltamivir and Zanamivir within 48 hrs, maybe bc any more days after that it will solve quickly on its own? Good for Influenza A&B. Rimantadine and Amantadine only good for Influenza A.

Give flu vaccine above 50, pregnant women, and health care workers, every year.
Give pneumococcal vaccine above 65, just once.

Strep throat becomes scarlet fever becomes rheumatic fever. Caused by strep pyo.
Strep throat = pharyngitis
Scarlet fever = fever + rash
Rheumatic fever = Jones criteria: joints, carditis, nodules, erythema marginatum, sydenhams chorea.

LUNG INFECTIONS

Bronchitis most likely caused by strep pneumo. You get mild cough, fever, and neg CXR.

TB and lung abscess both have fever, cough, air-fluid levels on CXR. Difference is TB more often find in recent immigrants, homeless, prisoners, and health care workers. Abscess more often find in ppl w bad teeth, and risks of aspiration, like in seizure, intubation, alcoholics. THey aspirate bad stuff that infects their lungs and cause them pneumonia. Then parts of their lungs start to cavitate and rot… This is a lung abscess, and it smells baaaaad. Most accurate Dx test for abscess is biopsy. Rx. W penicillin and clindamycin – For above the diaphragm or respiratory anaerobes.

Most pneumonia caused by strep pneumo. What is important is not necessarily the organism, but how serious the patient is (and therefore whether or not to admit the pt).

Pneumonia – fever, cough, sputum.

Mycoplasma (walking pneumonia) – young healthy ppl in community. Get cold agglutinin test best initial, serology most accurate. Macrolide, quinolone, doxycycline – rx atypicals

Legionella – more often older ppl w/ COPD. Have GI, CNS problems. Get urine antigen test first, but culture most accurate. Macrolide, quinolone, doxycycline.

PCP – HIV pt under 200 T cells w/ SOB. Rx TMP/SMX and oxygen. Add steroids if severe (PO2 less than 70, or AA gradient greater than 35). Rash most common AE w/ TMP/SMX (Bactrim). If have rash, use IV Pentamidine for active disease rx instead. If for prophylaxis use dapsone or atorvaquone.

Coxiella – pt w/ close contact w/ animals (sheep) exposure. Macrolide, quinolone, doxycycline.

Community Acquired Pneumonia – most likely from pneumococcus
Hospital Acquired Pneumonia – most likely from gram neg (ecoli, pseudomonas, klebsiella, enterobacter, citrobacter, morganella – often get these at hospital).

You don’t know what organism causes the pneumonia until 3 days of sputum culture, so don’t base rx decision on organism but on whether or not you admit the pt.
Outpt – macrolides first choice, new fluoroquinolone (levo, moxi, gatefloxacin)
Inpt – new fluoroquinolones, 2/3 gen cephalosporins w/ doxy or macrolide, or betalactam/betalactamases.

TB pneumonia – fever, cough, sputum. Often from immigrants, prisoners, homeless. Not lung abscess bc not smelly. CXR best initial test for all respiratory infection. For TB, show apical infiltrate (where more air is). After this, do sputum acid-fast bacilli stain and culture (but results take 6 weeks). Why not do empiric therapy before? Bc u’ll destroy the results of culture. You don’t hafta wait for results for culture. When stain is positive, start empiric rx: RIPE. Use INH/RIF/PZA/Ethambutol for first 2 months, followed by INH/Rifampin for 4 months. 6 months rx total. Pyrazinamide reduce rx down from 9 mo to 6 mo.

All of them are hepatotoxic. INH cause urinary loss of B6, causing neuro problems (folate def no neuro prob). Rifampin causes Red bodily fluids. Eye problems in Ethambutol. Uricemia in Pyrazinamide, but harmless.
Rifampin = Red bodily fluids, but harmless
Ethambutol = Eye problems. Stop if develop optic neuritis.
INH = Neuro problems. Give pyridoxine.

TB osteomyelitis, TB Brain infection, Miliary TB, Pregnant (bone, brain, military, pregnant) – rx tb for more than 6 months.
TB meningitis and TB pericarditis – also add steroids.

PPD is only for screening! Not for acutely symptomatic pts! Only screen in asymptomatic ppl!
Pos if greater than 10mm. But in close contacts, HIV, ppl on steroids, greater than 5mm is Pos dx. Pos PPD = 10% lifetime risk of developing TB. If PPD pos, do CXR. If CXR neg, Give INH for 9 months to reduce risk of developing TB to 1%. If CXR pos, then check sputum, then give the normal TB rx.

If first PPD neg, give second test in 1-2 wks to make sure is true negative. When reading PPD, redness doesn’t matter. Induration matters.

Don’t consider BCG vaccination history when interpreting PPD. There is little correlation. Still continue to give INH for 9 mo if pos.

TB Pericarditis (calcification and fibrosis) – needa remove the pericarditis

Zeel-Nielson stain – acid fast stain for TB

EMPIRICAL ANTIBIOTIC TREATMENT FOR COMMUNITY ACQUIRED PNEUMONIA

CAP – rx macrolide, or doxy.
CAP + comorbidities – rx macrolide + BL, or resp quinolone.
HAP non-ICU – rx macrolide + BL, or resp quinolone.
HAP ICU – rx BL + Macrolide, or BL + resp quinolone

Community Acquired Pneumonia (CAP) – likely strep pneumo
Hospital Acquired Pneumonia (HAP) – likely staph aureus or G neg rod 

Preferred macrolide: clarithromycin, azithromycin
Preferred BL: high-dose amoxicillin, amox/clav, ceftriaxone, others

If suspect MRSA, add linezolid or vanco
If suspect Pseudomonas, use antipseudomonal/antipneumococal BL like piperacillin/tazobactam, cefepim, imipenem, meropenem. 

If allergic to BL, substitute w aztreonam.

Resp fluoroquinolones are: levofloxacin, moxifloxacin, gatifloxacin, and gemifloxacin. These got their nickname bc of they are especially good at fighting strep pneumo while still being effective against Hib, atypical. They can fight PCN/Macrolide-resistant strep pneumo, and therefore can be used as monotherapy for CAP.

GI INFECTIONS

Diarrhea – first find out if there is RBC or WBC or not.

If there is blood, could be campylobacter (most common bloody diarrhea, guillian barre), salmonella, shigella (HUS), yersinia, or ecoli O157 (HUS, hamburger), all invasive pathogen. If have serious life-threatening infection like fever, diarrhea, abd pain, hypotension, then rx fluoroquinolone.

If there is no blood, could be viral, staph (creamy foods), b. cereus (Chinese food), giardia (campers/hikers), or cryptosporidium (HIV pts). Blood excludes these 5.

Hemolysis, high creatinine, low platelets, think HUS.

Shellfish, seafood – think vibrio parahemolyticus and vibrio vulnificus (liver, skin disease)

Best dx test is stool culture. Rx most likely effective is quinolone (ciprofloxacin)

Vomiting, no blood – think staph or b.cereus bc have preformed toxin – irritate stomach, making you vomit.

Giardiasis — stool ELISA antigen-antibody test better than 3-ovum detection for dx. Rx w metronidazole or tinidazole. Obstruct lacteals in villi so looks like fat malabsorption.

Cryptosporidium – not seen in stool ovum, but seen in modified acid fast stain. Rx by raising T cells w/ retrovirals.

Viral diarrhea – no specific dx test and doesn’t require rx.

C diff – associated w antibiotics. Dx test is toxin bc difficult to culture. Rx metronidazole. If pt gets better w metronidazole and recurs in 2 weeks, then retreat w metronidazole. Only give vanco if metronidazole didn’t get better in the first place.

Rotavirus most common diarrhea in kids.

ACUTE VIRAL HEPATITIS INFECTIONS

Dark urine, light stool, big liver, big spleen, weight loss, increased ALT,increased bilirubin – just know have hepatitis.

Hep A/E from food/water. Travelers need Hep A vaccine. Pregnancy worst in Hep E. No rx. Self resolves.

Hep B/C/D from blood, sex, perinatal. No rx for acute.

Pt w chronic liver disease should be vaccinated for all Hep.

Chronic Hep C most common cause of needing liver transplant in US, not alcohol.

Dx Hep B w surfaceAg, eAg (DNA polymerase), core Ab, surface Ab etc. Dx all others w just IgM (acute), IgG (chronic).
Acute Hep B has surface Ag and E Ag. E Ag most direct way of knowing amount of viral replication.
Chronic Hep B has surface Ag for more than 6 mo.
Vaccinated pt only make surface Ab.

Rx Hep C w interferon and ribavirin together.
Interferon ae flu-like sx – aches, pain.
Ribavirin ae RBC anemia.

Rx Hep B w interferon or lamivudine or entacavir or adefovir. Best to rx w eAg pos pts bc block polymerase most.

SEXUALLY TRANSMITTED INFECTIONS

Cystitis or urethritis: both have frequency, urgency, burning, dysuria, but urethritis also has discharge. Discharge without dysuria would still be urethritis.

Swab, stain, DNA probe, culture then treat. Rx w one gonorrhea drug and one Chlamydia drug.
Gonorrhea: Cefixime, ciprofloxacin, ceftriaxone.
Chlamydia: Doxycycline, Azithromycin.
Ceftriaxone+Azithromycin is a single dose drug.

Tetracycline is never the answer because it is replaced by doxycycline!!

Lower abd pain + cervical motion tenderness and increased WBC = pelvic inflammatory disease. Also rx with 1 chlamydia drug + 1 gonorrhea drug.

Best initial step for cervical motion tenderness and lower abdominal pain in women of child-bearing age: bHCG (pregnancy test) best to rule out pregnancy (rule out ectopic preg), then do culture from cervix swab.

If have gonorrhea, also rx for chlam
If have chlam, don’t need to also rx for gonorrhea, bc much less common.

Disseminated gonorrhea – polyarticular disease – lotsa petechial skin lesions, tenosynovitis (tendon). Culture pharynx, cervix, rectum, urethra to find it. Culture all around bc just joint tap isn’t very sensitive.

Gonorrhea doesn’t cause ulcerative genital disease. Doesn’t ulcerate!! Instead, Syphilis, Chancroid (h ducreyi), Lymphogranuloma venereum, granuloma inguinale, herpes when vesicles become unroofed, can all become ulcerative.

Syphilis – Chancre painless ulcer/nodes firm vs Chancroid painful and soft (ducreyi = “do cry”). Rx Chancroid w Azithromycin.

Lymphogranuloma venereum – painful lymph nodes. Chlamydia (L1-L3 subtypes). Not seen on gram stain bc intracellular, therefore dx w serology. No capsule, no vaccine (bc rapid antigenic variation), glucose fermentation (vs. meningococci does both maltose and glucose, has polysach capsule, and vaccine). Remember Gonorrhea cause septic arthritis, neonatal conjunctivitis, PID, Fitz Hugh Curtis. Remember Chlamydia cause Reiter’s Syndrome (reactive arthritis – cant see, cant pee, can’t climb a tree).

Granuloma inguinale – beefy red ulcers – donovanosis – dx w bx. See Donovan bodies. Rx w sulfa or ceftriaxone.

Syphilis – dx primary syphilis w darkfield bc RPR only 75% sensitive during this stage. Spontaneous resolution of chancre w/o rx. Secondary syphilis can do RPR bc have 100% sensitivity, bc now have lotsa ab, but get condylomata lata, rash, alopecia. Tertiary syphilis RPR back to 75% se. Neurosyphilis – mainly see neuro problems. Aortitis and gummas (skin) rare.

Syphilis – screen w/ RPR/VDRL. Confirm w/ FTA. But darkfield in primary syphilis!!!

Primary and Secondary Syphilis rx w 1 IM shot of Pen. Tertiary IV Pen. If allergic, rx Doxycycline, or do Penicillin Desensitization (give gradually more and more dose in controlled setting). If pregnant, still use penicillin (and do desensitization if needed).

Herpes Simplex – only one that cause multiple genital vesicles. Therefore go straight to rx w acyclovir, famciclovir, or valacyclovir. If roof comes off vesicles, can’t tell if it’s ulcer, so dx w Tzank prep first, then viral culture next. Rx acyclovir-res herpes w foscarnet.

URINARY TRACT INFECTION

Cystitis –> pyelonephritis –> abscess.

Cystitis and pyelonephritis both give freq, urg, burn, dysuria. But cys cause suprapubic pain and pyelo cause flank pain. Cystitis common in women, but not in male, so scan for obstruction, stricture, stone, or tumor bc is anatomic prob. Can progress to pyelonephritis. Pyelo and abscess much greater fever than cys.

Dx see inc WBC in UA. Culture most accurate test. But if see dysuria and inc WBC, go ahead rx cystitis w Bactrim (TMP-SMX) or quinolone for 3 days. If complicated w stones, strict, tumor, obstruction, or have diabetes (bc neutrophils weak w glucose), then rx for 7 days. If in male, rx 14 days. Don’t wait for cult.
Bacteria in urine insig except in preg women.

For pyelo and abscess, rx w any Gram neg rx l ampicillin or gentamicin. Know it’s pyelo if have flank pain and big fever along w dysuria and inc WBC.

Abscess must be dx w US, CT MRI, or Biopsy (best). Rx w ab then drain bc is anatomical problem.

Nitrofurantoin only used for UTI in preg.

SKIN INFECTIONS

Strep viridans is a one-disease organism. Only causes endocarditis, so get an echocardiogram.

Scabies must be scraped out of skin burrows. Lice and crabs is on surface of skin. Scabies itch. Rx both w permethrin.

Fluconazole rx superficial fungal infections. Amphoteric in rx more severe fungal diseases, like in heart, brain, or blood. It has bad ae l hypo kalmia, tubular necrosis.

Molluscum contagiosum is contagious. To rx, just burn it off or use imiquimod to who’ve your body slough it off.

BONE INFECTIONS

See osteomyelitis in diabetic pt w periph arterial disease w ulcer that has spread to bone. Red swollen tender.

first test to rule out osteomyelitis is XR. If XR neg do MRI. If no MRI, do bone scan instead.

If XR pos, do biopsy. If find is staph rx w ox clox diclox naf. If find is gram neg, rx ciprofloxacin which goes into bone, only oral med for osteomyelitis. If find is MRSA rx w vanco linezolide. Track the infection w ESR to decide how long to rx.

U can also do joint tap. If see less than 2000 cells, then is normal. If see up to 20,000 then is inflammation l gout, pseudogout, RA. If see above 50,000 then is infection.

Artificial joint causes most joint infection vs osteoarthritis or RA.

ENDOCARDITIS

Fever + murmur = endocarditis. May also have risk factors like drug use or valve replacement.

Endocarditis has a 100% mortality rate, even though takes a while to get there. Most ppl w endocarditis die from post infectious glomerulonephritis. Roth spots, janeway lesions, and osler nodes (all caused by clots) for the most part are irrelevant, and are only useful as symptoms for diagnosis (along w fever and murmur and risk factors) when blood cultures come back negative.

First initial diagnostic test is blood culture, NOT echocardiogram! After have pos bcx, do tte or tee to confirm (bc echo in general less sensitive). Tee more sensitive than tte bc esophagus is right behind left atrium.get great view.

Dx w duke’s criteria.

Empirical rx for endocarditis while waiting for bcx is vanco and gentamycin. Vanco rx the possible staph or strep. Genta rx possible G neg bugs. Also both synergistic as vanco pokes hole and aminoglycoside enters to kill ribosome.

After bcx comes back, then change rx. If staph, rx ox clox diclox naf. If MRSA, rx vanco, linezolid, or daptomycin. If viridans, rx penicillin or ceftriaxone. Rx at least 4 wks but if resistant l in MRSA or mre, rx 6 wks. If strep bovis, also do endoscopy bc associated w colonic pathology.

If neg bcx, prob hacek, which r g neg.

Single strongest indication for surgery is CHF which is irreversible.

Do endocarditis prophylaxis for ppl who have both a heart defect and major procedure that may let endocarditis bacteria in.
Major defects: AS, MS, AR, MR, VSD
Procedures: dental extraction, GI surgery, hemicolectomy, prostate bx, transurethral prostate resection.
These don’t cause bacteremia: cardiac cath, skin biopsy, gyn procedures, flexible GI scopes.
These defects aren’t endocardio risky: ASD, pacer, CABG. Bc cabg and pacer happen outside of heart. In ASD, LA and RA pressure about the same… No damage risk.
Needa have both bacteria and place for bact to stick in order to be at risk for endocarditis.

PPx: for dental procedures, give amoxicillin 1 hr before. If pen allergic, give clinda.
For GI or urinary procedures, give ampicillin. If pen allergic, give vanco.

LYME DISEASE

Lyme rash is actually more accurate than serology in telling u dx. Do serology only if you don’t see rash and have joint pain or bells palsy. Rx w doxycycline, ceftriaxone.

If someone got bitten by tick but asymptomatic, no need to do serology or rx.

AIDS

What is important is when to give prophylaxis and what the ae are.

When t cells under 200, give PCP ppx… TMP/SMX , but ae rash l all sulfa. If allergic, rx dapsone (unless have g6pd def), or atovaquone (also ppx malaria).

When t cells under 50, give MAI/MAC ppx… Azithromycin, give once a week

No routine herpes (acyclovir)/cmv (gancyclovir) prophylaxis.

Bactrim is toxoplasmosis ppx so already on it.

Ppd > 5mm at any t cell count. Give INH 9 mo.

Everyone w HIV should get Flu and Pneumovax vaccine at any t cell count.

Anemia — Zidovudine
Hyperglycemia, Hyperlipidemia – protease inhibitors
Peripheral neuropathy – Stavudine, Didanosine
Renal stones — Indinavir

Lamivudine – also rx hep B

Efavirenz – CI in pregnancy (only one). But if woman becomes pregnant while already on HIV meds bc t cell low, continue meds, bc death of mother is greatest birth defect.

High viral load in pregnancy = above 1000.

Start antiretrovirals when t cells dip below 350, but this guideline keeps changing, so usmle step 2 wont ask.

If woman w HIV has high T cell count, doesn’t need HIV meds for herself, but need just to prevent transmission to her baby. Give during 2nd and 3rd trimester.

Do C section only if viral load is not controlled (greater than 1000) or t cell is low.

Transmission of HIV from mother to child is 25-30% w no meds. W meds, it’s less than 2%.

If you accidentally get poked by HIV pos needle or if condom broke, give 2 NRTI (often emtricitabin or tenofovir bc 1 pill once per day easy) and PI or efavirenz for 1 month prophylaxis. If get stuck on HIV unknown needle, no ppx.

Can’t get HIV from kissing.

Oral thrush, kaposi’s sarcoma, herpes zoster, – happens in moderate immunosuppression (t cell 200-500). Oral thrush rx w oral or topical antifungals (nystatin, fluconazole, etc.). Kaposi’s – no antiviral drug, so rx HIV. Herpes Zoster rx w acyclovir.

Less than 200: PCP: start TMX/SMX! Severe PCP means Po2 less than 70 Aa gradient greater than 35 = start steroids. If allergic bactrim for ppx, rx dapsone atovaquone. If allergic to bactrim for rx, rx IV pentamidine!

Less than 100: Toxoplasma – rx pyrimethamine, sulfadiazine, and see if go away. Prefer over brain biopsy.

Less than 50: CMV: blurry vision. Rx ganciclovir ae decreased WBC. Foscarnet ae renal toxicity.
If taking antiretrovirals and T cells go up, don’t stop antiretroviral drugs! But you can stop ganciclovir and foscarnet, bc increased T cell will prevent further CMV, etc.

MISCELLANEOUS

RMSF – actually happen in the South, not Rocky Mountains. Fever and headache, then rash later. Rx Doxycycline.

Types of Aspergillus
Allergic Bronchopulmonary Aspergillus – like asthma. Rx w steroids.
Necrotizing (esp in neutropenic ppl) – rx amphotericin (ae distal renal tubular acidosis and hypokalemia), Voriconazole, Caspofungin, echinocandins

Blastomycoses, Cryptococcus, etc. also rx amphotericin, voriconazole, caspofungin,echinocandins.

Toxic Shock Syndrome vs. Staph Scalded Skin. TSS has hypotension, liver, kidney disease.