Infectious Disease

Question 1

MRSA?

Answer 1

Px: Boil or pimple type lesion; described as “pustules on an erythematous base”.

TX: HA- IV Vancomycin
CA- Oral Clindamycin
Oral Bactrim

Question 2

Sepsis?

Answer 2

Px: Fever, RR >20, Hypotension, WBC count less than 4,000 or greater than 12,000, HR > 90.

Dx: Lactate > 18. Respiratory alkalosis with a metabolic acidosis.

Tx: Fluid- Iv crystalloid if fails, norepi. Empiric Piperacillin-tazobactam (Zosyn) + Vancomycin.

Question 3

Scarlet fever?

Answer 3

GABHS (Streptococcus pyogenes)
PX: Winter/Spring; “sandpaper feel” rash to neck/trunk –> UE. Pastia’s lines. strawberry tongue, circumoral pallor.

Dx: RADT/Throat cx

Tx: Amoxicillin, if ax clindamycin.

Question 4

Diptheria?

Answer 4

Px: grayish-white membrane, bull neck, chronic non-healing ulcer, myocarditis.

Dx: Throat swab –> gram-positive rods with blue and red metachromatic granules, + Elek Test.

Tx: Diphtheria antitoxin immunoglobulin, PEN G.

Question 5

Tetanus?

Answer 5

Gram-positive, spore-forming rod –> tetanospasmin.
Px: Trismus, difficulty in feeding

Dx: Clinical or cx or test serum anti-tetanus immunoglobulin G.

Tx: Human tetanus immune globulin (TIG) and Metronidazole.

Question 6

Botulism?

Answer 6

gram-positive bacillus, anaerobic, spore-forming bacteria.
Raw honey, canned foods.
Px: Symmetric cranial nerve palsies and descending flaccid paralysis. “4 Ds”, diplopia, dysarthria, dysphonia, dysphagia. Floppy baby syndrome w/ hypnotic & weak cry.

Dx: Toxin Assays

Tx: Antitoxin (equine-derived heptavalent) For infant, human botulinum immunoglobulin (BIG-IV). For wound, penicillin or metronidazole.

Question 7

Clostridial Myonecrosis (Gas Gangrene)?

Answer 7

Traumatic inoculation with Clostridium perfringens (obligate anaerobe, gram-positive rod).
Px: Intense pain, bullae and crepitus.

Dx: Clinical, X-rays = air in the soft tissues, Cx = gram-positive bacilli.

Tx: surgical debridement and excision – possible amputation
IV antibiotics (Penicillin plus Clindamycin).

Question 8

Cholera?

Answer 8

Gram-negative rod. Fecal contamination of water and food. Shellfish w/o adequate cooking.
Px: Large volumes of watery diarrhea -> “rice water stool”.

Dx: Culture

Tx: Water and electrolytes. etracyclines/fluroquinolones –> Shorten symptom duration.

Question 9

Lyme?

Answer 9

Motile spirochete and transmitted via the Ixodes scapularis (“blacklegged”) deer tick. May to September.

Px: expanding, warm, annual, erythematous rash w/ central clearing (bull’s eye/target appearance). Facial nerve palsy, Arthritis, Cardiac block, Erythema migrans.

Dx: Clinical. ELISA -> if positive (or equivocal) then Western Blot for confirmation.

Tx: Early localized, disseminated, & prophylaxis- Doxycycline.
Preg.- Amoxicillin
Late To Severe: IV Ceftriaxone

Question 10

Rocky Mountain Spotted Fever?

Answer 10

Rickettsia rickettsia. Gram-negative, very short rods & obligate intracellular bacteria.
Dog ticks.
Px: Macules to petechiae first on palms & wrists and soles & ankles THEN moves inward to the trunk.

Dx: Clinical. ELISA testing is used to test for IgM and IgG antibodies.

Tx: Doxycycline
Chloramphenicol is 2nd line, and used in pregnancy.

Question 11

Varicella Zoster Virus (HHV-3): Chicken Pox ?

Answer 11

Px: Erythematous macules that become papules then vesicular (crops) then crust over on the face and then goes to the trunk before spreading to the extremities.
Scabs in various stages of evolution.

Dx: Clinical. PCR for viral DNA

Tx: Healthy children < 12: Acetaminophen & Calamine lotion. Adults, adolescents > 12, immunocompromised = acyclovir.

Question 12

Varicella Zoster Virus (HHV-3): Shingles?

Answer 12

PX: Pain. Unilateral rash within a single dermatome that does not cross the midline. Hutchinson’s sign. Ramsay Hunt syndrome.

Dx: Same as chickenpox.

Tx: Valacyclovir
Post Post herpetic neuralgia tx = Gabapentin.

Question 13

Epstein-Barr Virus: HHV-4?

Answer 13

infectious mononucleosis. Also associated with Hodgkin’s disease.

Px: Triad: lymphadenopathy (MC posterior cervical), splenomegaly (wk 2-3), exudative pharyngitis.

Dx: Lab tests reveal lymphocytosis w/ > 10% atypical lymphocytes (Downey cells) w/ levated LFT’s, ↑ bilirubin and
Heterophile antibody test (monospot) (wk. 3)

Tx: Supportive and Increased risk of splenic rupture so avoid contact sports.

Question 14

Cytomegalovirus (CMV): HHV-5?

Answer 14

Px: Like mono but reactivation, Colitis: diarrhea, fever, abdominal pain, bloody stools. (MC)
Retinitis: decreased visual acuity and floaters. (important cause of blindness in AIDS)
Esophagitis: odynophagia with large superficial ulcers on upper endoscopy.

Dx: Labs w/ atypical lymphocytosis; Heterophile antibody-negative and Cytopathology: shows intracellular inclusions surrounded by a clear halo “owl eye cells”.

Tx: Primary = supportive
Reactivation = Ganciclovir but for HIV + with CD4 < 50 cells/uL, Valganciclovir is prophylactic.

Question 15

Roseola Infantum: HHV-6?

Answer 15

Px: Fever, resolves, then rose pink, maculopapular, blanchable rash beings on the trunk and peripherally.

Dx: Clinical

Tx: Supportive

Question 16

Erythema Infectiosum?

Answer 16

Human parvovirus B19.

Px: “slapped cheek”. Erythematous maculopapular rash on proximal extremities (usually arms and extensor surfaces) and trunk, which fades into a classic lacelike reticular pattern.

Dx: clinical, IgM/IgG serology and PCR assay can be performed if pregnant/immunocompromised.

Tx: Symptomatic

Question 17

Influenza?

Answer 17

Orthomyxoviridae family. In fall/winter.

Px: Abrupt onset ever/chills, muscle/body aches, headache.

Dx: Clinical, RADT, GS = Viral culture, RT-PCR.

Tx: Oseltamivir (Tamiflu) PO. For A, Amantadine

Question 18

Measles (Rubeola)?

Answer 18

Paramyxovirus.

Px: Prodrome of Cough, Coryza, Conjunctivitis (the 3 C’s) +/- Koplik spots. Followed by macular rash and fever. Rash typically starts on the head (especially the hairline/ears) and spreads downwards can include palms and soles.

Dx: Clinical. Serology: IgM in a single specimen of serum or oral fluid and IgG antibody levels. RT-PCR to confirm.

Tx: Supportive care: fever reduction, rehydration, superinfection prevention measures
High-dose vitamin A: In patients with known nutritional deficiencies
Ribavirin: In cases of pneumonia
Measles immune globulin (if high risk for complications).

Question 19

Rubella (German Measles)?

Answer 19

Togavirus

Px: Rash (generalized maculopapular) typically begins on face and spreads distally. “3-day measles”.
Petechia on soft palate (Forchheimer spots), Lymphadenopathy, particularly occipital and postauricular

Dx: serologic testing- (IgM) antibody in a single serum sample or rise in (IgG) antibody titer.

Tx: Supportive.

Question 20

Mumps?

Answer 20

Paramyxovirus.

Px: Parotid gland swelling + pain.

Dx: Clinical. serologies or PCR. w/ increased amylase.

Question 21

Rabies?

Answer 21

Rabid animal bites. rhabdoviridae.

Px: pain, paresthesia, itching at initial site of the bite. encephalitis, hydrophobia (painful laryngospasm after drinking, seeing or hearing water).

Dx: Negri bodies. Direct fluorescent antibody testing of a biopsy specimen of skin from the nape of neck.

Tx: None. Coma induction.

Question 22

Gonorrhea?

Answer 22

Gram-negative bacteria.

Px: septic arthritis. Men- urethritis. Mucopurulent/copious urethral discharge.
Women- mucopurulent vaginal discharge and intermenstrual bleeding, urethritis
Infection of Bartholin’s gland, Pelvic inflammatory disease (PID):lower abdominal pain and tenderness, Fever Cervical motion tenderness (CMT), Adnexal tenderness
Perihepatitis (Fitz-Hugh-Curtis syndrome)

Dx: Nucleic acid amplification tests (NAATs) using the patient’s urine or a vaginal swab*. Gram stain- gram-negative intracellular diplococci.

Tx: Ceftriaxone and Azithromycin (you ALWAYS treat for chlamydia also)
PID: Ceftriaxone + doxycycline. Disseminated gonococcal infection management IV ceftriaxone.

Question 23

Syphilis?

Answer 23

Treponema pallidum; gram-negative spirochete bacteria.

Px: Primary- painless ulcer and Nontender regional lymphadenopathy. Secondary- Diffuse bilateral maculopapular lesions (including the palms and soles), wart-like, moist lesions involving the mucous membranes & other moist areas. Tertiary- noncancerous granulomas on skin, Tabes dorsalis (ataxia, areflexia, “lightning-like” burning pain and weakness), small, irregular pupil that constricts with accommodation but is not reactive to light, & cardio.

Dx: Rapid Plasma Reagin (RPR) & Venereal Disease Research Laboratory (VDRL) - looks for titers (of antibodies) to non-treponemal antigens. Fluorescent treponemal antibody absorption (FTA-ABS) and Darkfield microscopy.

Tx: Penicillin G benzathine; Neurosyphilis- IV Penicillin G potassium

Question 24

Chlamydia?

Answer 24

Chlamydia trachomatis MC.

Px: Women: cervicitis, urethritis, salpingitis, PID
Men: urethritis, epididymitis, proctitis
Urethritis = watery – mucopurulent discharge, pruritis, dysuria.
Reactive arthritis = arthritis, urethritis, and uveitis.
Fitz-Hugh-Curtis syndrome: perihepatitis.

Dx: NAATs

Tx: Azithromycin OR Doxycycline.

Question 25

Chlamydia: Lymphogranuloma Venereum (LGV)?

Answer 25

C. trachomatis L1-L3 immunotypes. Px: Painless genital ulcer Secondary stage 2-6 weeks later w/ painful inguinal and/or femoral lymphadenopathy. Dx: Clinical Tx: Doxycycline

Question 26

Genital Herpes HSV-2?

Answer 26

Px: Prodrome of systemic features (fever, headache, malaise) with localized pain and itching, dysuria, or tender lymphadenopathy Painful genital ulcers: begins as erythematous lesions then develops into group of vesicles and pustules Dx: PCR, Direct microscopy- multinucleated giant cells, and +/- eosinophilic intranuclear inclusions, & Direct fluorescent antibody or type-specific serologic tests. Tx: Acyclovir, valacyclovir

Question 27

Human Papillomavirus?

Answer 27

Px: Serotypes 1-4 = skin warts Serotypes 6, 11, 16, 18 = genital warts = Condylomata acuminata. "Cauliflower-like" lesions, asymptomatic, but itching, burning, pain, and tenderness are frequent. Dx: Clinical, PCR testing, or biopsy of lesion. Tx: Wart removal (cryoablation w/ liquid nitrogen), Topical Imiquimod & Podofilox are patient applied, Podophyllin, Bichloroacetic acid, Trichloroacetic acid (TCA) are clinician applied.

Question 28

HIV?

Answer 28

Human T-cell lymphotropic retroviruses. PX: Acute- Fever, lethargy, sore throat and generalized lymphadenopathy Maculopapular rash on the trunk, arms and legs. Middle/Latent- AIDS-related complex (ARC)-->fevers, fatigue, weight loss and lymphadenopathy. Late/Immunodeficiency- CD4 count below 200 u/uL or a CD4+ T cell percentage of total lymphocytes of < 14% And/or at least 1 AIDS-defining condition (opportunistic infection(s) or illnesses associated with immunosuppression). Pneumocystis pneumonia and Kaposi’s sarcoma. Dx: 4th-generation enzyme immunoassay (EIA) for HIV-1 and -2 if +, HIV-1 and -2 antibody differentiation immunoassay. Indeterminate result: FDA-approved HIV-1 nucleic acid test. CD4+ T cell count (assess immune function) Viral RNA load (assess viremia) Tx: Highly Active Antiretroviral Therapy (HAART). 2 different NRTIs plus an INSTI. Post exposure prophylaxis: taken within 72 hours of exposure, 3 drug regimen x 28 days. Pre-exposure prophylaxis (PrEP): Reduce the risk in uninfected high-risk individuals: 2 drug regimen.

Question 29

Trichomonias?

Answer 29

Protozoa Trichomonas vaginalis, a pear-shaped organism with flagella. Px: malodorous, frothy yellow-green vaginal discharge, vaginal itching and dysuria. Cervical petechiae (strawberry cervix). Dx: NAAT Tx: Metronidazole

Question 30

Congenital syphilis?

Answer 30

Px: Early < 2 y/o = mucocutaneous (syphilitic rhinitis, rash), hematologic abnormalities, CNS & pulmonary complications Late > 2 y/o = facial abnormalities (saddle nose deformity, Hutchinson teeth), saber shins (anterior bowing of tibia), chorioretinitis, sensorineural hearing loss and developmental delays. Tx: IV Penicillin G

Question 31

Congenital Herpes?

Answer 31

Px: Localized to the skin, mouth and eyes CNS disease: seizures, tremors, lethargy, poor feeding, encephalitis Disseminated: temperature instability which can lead to respiratory distress, DIC and septic shock Tx: IV acyclovir

Question 32

Congenital Varicella?

Answer 32

``` Px: Scarring skin lesions, abnormalities of the limb (hypoplasia of bone and muscle) Ocular abnormalities (cataracts, chorioretinitis) CNS abnormalities (seizures, cognitive deficits) ```

Question 33

Congenital Rubella?

Answer 33

Px: Deafness, cataracts, and cardiac disease. “blueberry muffin lesions” (petechia and purpura), hemolytic anemia, bone lesions and lymphadenopathy.

Question 34

Zika Virus?

Answer 34

Flavivirus transmitted by Aedes mosquito cause Zika virus. Px: 5 main features: severe microcephaly, decreased brain tissue, eye damage (macular and retinal changes), congenital contractures (clubfoot, etc.), hypertonia restricting body movement. Tx: Wait at least 3 months after Zika virus onset or last possible exposure before having unprotected sex. Pregnant women should avoid travel to areas below 6,500 ft where mosquito transmission is ongoing.

Question 35

Malaria?

Answer 35

Plasmodium genus and transmitted by mosquitoes (through bites) of the Anopheles genus. MC falciparum. Px: Paroxysms- “cold stage” and then “hot stage”, fever, chills, headache, exhaustion, sweats. Cerebral malaria symptoms can include altered mental status, delirium, seizures and coma. Blackwater fever symptoms can include severe hemolysis, hemoglobinuria and renal failure. Dx: *Blood film stained with Giemsa. The ”thick” smear is used to screen for the presence of organisms and the ”thin” smear is used for species identification. CBC often reveals leukopenia, hemolytic anemia and thrombocytopenia. Tx: Chloroquine (also prophylaxis). If life-threatening infection: IV Quinidine gluconate Prophylaxis for travel.

Question 36

Chaga's Disease?

Answer 36

Trypanosoma cruzi. When the host is bitten (most commonly around the mouth or eyes, hence the name “kissing bug”) by the infected reduviid bug and trypomastigotes enter the blood. Px: Acute- A bite around the eye can cause unilateral palpebral swelling called Romana’s sign. Facial edema and a nodule (chagoma) near the bite. Chronic- Cardiac = dilated cardiomyopathy, CHF, arrhythmias (most deaths occur b/c arrythmias) GI = megacolon (progressive constipation, colicky abdominal pain and bloating) and megaesophagus (progressive dysphagia and regurgitation of food) CNS = destruction of nerve cell ganglia Dx: Acute- Peripheral blood smear will reveal the trypomastigotes (flagellated motile form). Chronic- ELISA EKG = may show arrythmias Echocardiogram = cardiomegaly with apical atrophy or aneurysm. Tx: Acute phase or the chronic phase, but WITHOUT significant cardiac or GI disease: Benznidazole or Nifurtimox. No treatment for the chronic form with significant cardiac or GI disease.

Question 37

African sleeping sickness?

Answer 37

Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense. Bite by Tsetse fly in Africa. Px: Early- Painless lesion (“trypanosomal chancre”) at the site of the fly bite. Intermittent weekly fever and lymphadenopathy develop. Enlargement of the posterior cervical lymph nodes is often seen (Winterbottom’s sign). Late- Encephalitis characterized initially by headache, insomnia and mood changes. Followed by muscle tremors, slurred speech and apathy that progress to day-time somnolence and coma. The sleepiness is caused by tryptophol released by the disease. Dx: EARLY Blood smears reveal trypomastigotes. Aspirate from enlarged LN can show parasites as well. ELISA = presence of anti-trypanosoma IgM antibodies LATE CNS = the presence of trypanosomes ``` Tx: Trypanosoma brucei gambiense Early = Pentamidine Late = Eflornithine & Nifurtimox Trypanosoma brucei rhodesiense Early = Suramin Late = Melarsoprol (+/- Nifurtimox). ```

Question 38

Toxoplasmosis?

Answer 38

Toxoplamsa gondii. Soil contaminated with cat feces is accidentally ingested. Px: Primary- Mono Reactivation- Encephalitis Chorioretinitis - posterior uveitis - eye pain and decreased visual acuity Dx: Microscopic examination of Giemsa-stained preparations can show crescent-shaped trophozoites during acute infections. Immunofluorescence assay / ELISA for anti-toxoplasma IgG antibodies Neuroimaging = MRI preferred -> multiple ring enhancing lesions Tx: Sulfadiazine (or Clindamycin) AND Pyrimethamine (with folic acid/Leucovorin to prevent folic acid depletion) Prophylaxis -> in patients with CD4 count below 100 First-line = sulfamethoxazole & trimethoprim (Bactrim DS).

Question 39

Toxoplasmosis: Prenatal Transmission?

Answer 39

Pregnant women should never handle cat litter. Treatment for a newly infected pregnant woman Spiramycin Px: chorioretinitis*, encephalitis/hydrocephalus and intracranial calcifications. The infant can also have fever, jaundice, hepatosplenomegaly. Dx: Immunofluorescence assay / ELISA for anti-toxoplasma IgM antibodies Tx: Sulfadiazine & Pyrimethamine

Question 40

Roundworms?

Answer 40

Ascaris lumbricoides. Px: Ascaris pneumonia, with cough, fever and eosinophilia. Abd pain or obstruction. Dx: Stool ova and parasite (O&A) test - microscopic evaluation will show the eggs in the stool Tx: Albendazole or Mebendazole Pyrantel if pregnant (after 1st trimester)

Question 41

Hookworms?

Answer 41

Necator americanus & Ancylostoma doudenale. ``` Px: Phase 1 (skin): resolves in a few days; cutaneous larvae migrans Phase 2 (transpulmonary) may be asymptomatic for this phase Phase 3 (GI): N/V/D Phase 4 (anemia): blood loss at site of attachment (small intestine) ``` Dx: CBC = hypochromic microcytic anemia Eosinophilia = increased IgE Stool guaiac = often positive Stool Ova & Parasite (O&P) - microscopic examination revels eggs in the stool. Tx: Albendazole or Mebendazole or Pyrantel.

Question 42

Pinworms?

Answer 42

Enterobius vermicularis. Px: Perianal pruritis, especially at night. Dx: THE SCOTCH TAPE TEST Tx: Albendazole, Mebendazole or Pyrantel retreat in 2 weeks.