HIV (+) patients who are not on HAART should have CD4 count measured every 3-‐4 months to determine optimal time to commence therapy.
HIV post-‐exposure prophylaxis in high-‐risk situations within 72 hours (e.g., post-‐ needle stick; exposure to any secretion with blood, breast milk, semen, rectovaginal, eye, mucous membrane, non-‐intact skin) = two NRTIs + either an NNRTI, integrase inhibitor or protease inhibitor = three drugs total for FOUR weeks.
In treatment-‐naïve HIV-‐positive patients, a three-‐drug HAART therapy should reduce viral load to <50/mL within six months. Virologic failure is defined as not having achieved <200 viral copies/mL by 24 weeks.
If presents >72 hours post-‐exposure of source of HIV was low-‐risk (urine, nasal secretions, saliva, sweat, tears [no visible blood in any as well]), post-‐exposure prophylaxis is not recommended.
Examples of NRTIs: tenofovir, lamivudine, emtricitabine, zidovudine Integrase inhibitor: raltegravir
Protease inhibitors: atazanavir, ritonavir
Gonorrhea Tx = single intramuscular dose of 250mg ceftriaxone plus oral doxy 100mg bid or 1g oral azithro stat
Tx for Strep pharyngitis is ten days of penicillin to prevent rheumatic fever.
Tx for bacterial conjunctivitis = erythromycin ointment, sulfa drops, or polymyxin/trimethoprim drops. Ciprofloxacin only for contact wearers (Pseudomonas).
Indication of adding steroids to TMP-‐SMX in pneumocystis infection is A-‐a gradient >35 mm Hg or PaO2 <70 mm Hg.
Tick paralysis is caused by toxin made in the salivary glands of Dermacentor ticks in North America and Ixodes in Australia. Paresis and ascending paralysis, and even respiratory failure/death, occur within 2-‐7 days of tick bite. Pupillary abnormalities are uncommon in tick paralysis. Removal of the offending agent (tick) is the treatment.
Intertrigo = candida/fungal infection of intertriginous areas (skin folds). Treatment is topical antifungals.
Erythrasma is a red/brown intertriginous plaque caused by Corynebacterium minutissimum. Treatment is topical fusidic acid or oral macrolides.
For C. difficile, Tx is oral metronidazole if pseudomembranous colitis is mild or moderate: WBC <15,000, creatinine <1.5 baseline and serum albumin >2.5g/dL. If outside these parameters (severe), start with oral vancomycin first. If ileus occurs (exacerbation of severe), add IV metronidazole or switch to rectal vancomycin. Surgery reserved for life-‐threatening cases.
The first recurrence of C. difficile is treated with oral metronidazole again if mild or vancomycin is severe. This is because it’s thought the first recurrence is due to germination of spores from the initial infection rather than being a second genuine infection. For the second recurrence, use pulsed oral vancomycin over 6-‐7 weeks. For subsequent recurrences, use fidaxomicin.
Tuberculous meningitis, military TB, and TB osteomyelitis are all treated with anti-‐TB therapy for twelve months, with RIP given for two months followed by RI for the remaining months.
Patients with TB are considered non-‐infectious after three negative sputum smears on three different occasions.
Prophylaxis of latent TB is INH for 9 months, rifampin for 4 months, rifampin + isoniazid for 4 months, or isoniazid + rifapentine for 3 months.
HIV-‐infected patients with syphilis of unknown duration or late-‐latent syphilis should have lumbar puncture performed before treatment with penicillin.
Tx for syphilis: Primary, secondary, or early latent (<12 months since Dx): IM benzathine penicillin G, 2.4 million units, as a single dose. Late-‐latent (>12 months since Dx), unknown duration syphilis, gummatous or cardiovascular tertiary syphilis: IM benzathine penicillin G, 2.4 million units, given once/wk for three weeks (3 doses total)
Neurosyphilis: IV aqueous crystalline penicillin G, 3-‐4 million units, every 4 hours, for 10-‐14 days
Early neurosyphilis can present with symptomatic meningitis, ocular syphilis and otosyphilis. Ocular syphilis can present as posterior uveitis, retinitis or optic neuritis. Otosyphilis can present with sensorineural hearing loss and/or tinnitus. Neurosyphilis can present during any stage of syphilis but most commonly occurs during secondary syphilis.
Congenital syphilis: IV aqueous crystalline penicillin G, 50,000 units/kg/dose, every 8-‐12 hours, for 10 days
Contagious ecthyma (orf) is caused by a poxvirus from the occupational exposure of herding sheeps/goats and begins as an erythematous papule on the hand that can blister.
Milkmaid’s blister (or milker’s nodule) is caused by a parapoxvirus from occupational exposure to the udders of cows and presents similarly to orf and can be maculopapular/vesicular.
Extrapulmonary blastomycosis can present as wart-‐like or pustular skin lesion
Patients with just a positive anti-‐HBcAb on serology need to have repeat HepB serology testing to ensure these results are correct. Then anti-‐HBcAb IgM and transaminases need to be measured, where presence of anti-‐HBcAb IgM indicates acute HepC infection in the window period (HBsAg and anti-‐HBsAb both absent). If anti-‐HBcAb IgM is negative but transaminases are positive or there are signs of liver disease, HBV DNA must be ordered.
Acute HepC infection: usually asymptomatic, but symptoms can include nausea, jaundice, and RUQ pain lasting 2-‐12 weeks. Aminotransferases are often elevated 10-‐20x upper limit. Diagnosis is made with HepC RNA PCR. After 12 weeks, positive anti-‐HCV antibodies will be seen.
HepC infection is resolved once: normal aminotransferases, negative HepC RNA PCR, and positive anti-‐HCV antibodies.
Window period for HepB is when HBsAg and anti-‐HBsAb are both negative. Anti-‐ HBcAb is often positive in this window period.
Eosinophilia can be seen in Addison disease, eosinophilic gastroenteritis, intestinal helminthosis.
The Centor criteria are used to predict the likelihood of Strep pharyngitis. The criteria are: 1) Fever, 2) Absence of cough, 3) Tonsillar exudates, 4) tender anterior cervical lymphadenopathy. The presence of three equates to a PPV of 50% (not so helpful), but 0-‐2 has an NPV of 80%. If two or more criteria are present, do a rapid strep test. If 0-‐1 criteria are present, don’t do the rapid strep test and it is likely viral. If the rapid strep test is negative and strep pharyngitis is strongly suspected, throat culture is the next best step.
Rectovaginal swabs for GBS are done at 35-‐37 weeks gestation in all women unless they meet the following criteria which obviates testing.
Indications for GBS penicillin prophylaxis: Hx of early-‐onset GBS disease in prior pregnancy, current pregnancy tested (+) for GBS within 5 weeks of delivery, current pregnancy had GBS bacteriuria or UTI regardless of proximity to delivery; and unknown GBS status PLUS at least one of the following: maternal fever >38, prolonged rupture of membranes >18 hrs, or preterm delivery <37 weeks.
Mere colonization with GBS in prior pregnancy is not an indication for prophylaxis in current pregnancy.
Penicillin, ampicillin or cephazolin prophylaxis for GBS is given 4+ hours before delivery.
If GBS prophylaxis is given 4+ hours from delivery, observe neonate for ≥48 hours. If GBS prophylaxis given <4 hours from delivery, you ask: is neonate <37 weeks gestation at birth (preemie) and/or were ROM >18 hours; if no to both, then observe neonate for ≥48 hours; if yes, then observe ≥48 hours AND perform a blood culture + full blood
Prophylaxis for meningococcus is rifampin (4 doses, one every 12 hours over two days), but ciprofloxacin (once orally, not routinely used in children) can also be used, and ceftriaxone (single IM shot) can be used in pregnancy.
Chlamydia trachomatus is strictly sexually transmitted. Young or high-‐risk pregnant women should be screened again in third trimester even if first trimester screening was negative.
Tx of chlamydia in pregnancy is erythromycin base (500 mg, qid, 7 days) or amoxicillin (500 mg, tid, 7 days). Azithromycin (1 g stat) is an alternative but has not been thoroughly tested in pregnancy. Erythromycin estolate and doxy are contraindicated in pregnancy.
Mechanism of EBV exanthema following inappropriate administration of ampicillin/amoxicillin is immune-‐mediated from circulating antibodies against penicillin derivatives.
Amoxicillin-‐clavulanate is the prophylaxis for P. multocida infection following a cat/dog bite, not erythro Doxy can be given in penicillin-‐allergic pts.
Tinea versicolor diagnosed is diagnosed with skin scrapings followed by KOH preparation showing hyphae and yeast. M. furfur inhibits transfer of pigmentation to keratinocytes.
Tx for ecthyma gangrenosum is IV antibiotics (antipseudomonals) alone, without surgical debridement.
Acyclovir/valacyclovir is indicated for 7-‐10 days within 72 hours of onset of Sx.
Varicella zoster vaccine is recommended for all adults >60 yrs. If zoster occurs once in an individual, there is only a 5% chance of another recurrence (i.e., one zoster experience doesn’t mean risk is high of another), but vaccine is still recommended.
Transmission of zoster is through direct contact only, whereas primary chickenbox infection is through direct contact and respiratory droplet. Those with mild varicella who are immunocompromised or those with disseminated varicella should be hospitalized.
Post-‐herpetic neuralgia can be treated with TCAs (amitriptyline), capsaicin cream, gabapentin, and long-‐acting oxycodone.
Pyelonephritis is Tx with IV antibiotics in unstable patients, recurrent pyelo, or stable patients with vomiting. Oral Abx are used only in first-‐time pyelo without vomiting.
Dx of Lyme disease is via ELISA then western blot of serum serology, not of arthrocentesis-‐derived fluid.
Lyme disease is Tx with a 28-‐day-‐course of doxycycline or amoxicillin. Use amoxicillin in children <8 or in pregnant women.
Tx of pneumonia in CF must cover Staph and Pseudomonas. Staph is most common cause of pneumonia <20 years of age in CF; pseudomonas is most common >20 years; at 20 years the incidence is roughly the same. Treatment therefore must be vancomycin (to cover MRSA due to increased risk of resistant staph in CF), tobramycin (an aminoglycoside more effective against pseudomonas than gentamicin), and either ticarcillin/clavulanate or pipericillin/tazobactam or meropenem or imipenem/cilastatin or ceftazadime or
If a healthcare worker incurs a needlestick injury and the patient refuses to give blood to test for HIV/HepB/HepC, do not draw the patient’s blood AND start post-‐ exposure HIV prophylaxis (2 NRTIs for 4 weeks +/-‐ protease inhibitor) immediately.
Hepatitis A vaccine should be given to all unimmunized patients with underlying chronic liver disease (e.g., HepC). HepC that presents with normal liver enzymes, mild hepatic inflammation and no fibrosis may be treated with observation.
Interferon and ribavirin are initiated if LFTs are raised, inflammation is at least moderate, or fibrosis is present.
Rheumatic fever: peak incidence 5-‐15 yrs, twice as common in girls; major criteria = JONES = Joints (polyarthritis), (supposed to be round heart shape = O = carditis), Nodules, Erythema marginatum, Sydenham chorea; minor criteria = FEAP = Rever, ESR/CRP, Arthralgias, Prolonged PR interval.
Diagnosis of RF = two major, or one major + one minor, or Sydenham chorea alone, or carditis alone.
Sydenham chorea develops 1-‐8 months after the Strep infection; carditis and arthritis develop within 3 weeks. Tx for Sydenham chorea is penicillin to eliminate carriage of Group A Strep. Corticodsteroids are reserved for severe cases.