ID Flashcards
Lyme disease
Carrier/Type/Bug + Drug, Sx (early and late), Dx
Carrier: Lxodes scapularis tick
Type: Spirochete
Bug: Borrelia burgdorferi
Sx:
Early: erythema migraines (1-2 weeks after bite and not painful), uni/bilateral CN VII palsy, meningitis, carditis, migratory arthralgia
Late: Arthritis (afebrile, well appearing, can bear weight), encephalitis, peripheral neuropathy
Dx:
- Virology testing is often falsely negative in early infection due to incomplete development of antibodies. Therefore, patients with early localized disease are diagnosed clinically and treated empirically.
- Patients with early disseminated or late disease should undergo testing with ELISA then Western blot analysis
Drug:
- 1st line: Doxycycline (can reange from 10-28 days)
- Amoxicillin or cefuroxime for children and pregnant woman
- If treating for <21 days, patients <8 can use doxy
Rocky Mountain spotted fever
Carrier/Type/Bug + Drug, Sx, labs, Dx, Comp
Carrier: dog tick
Type: bacteria
Bug: Rickettsia rickettsii
Sx:
- Nonspecific fever, headache, myalgia, arthralgia
- Macular and petechial rash on wrist and ankles
Labs: decreased platelets & sodium and increased AST & ALT
DX: Rickettsia serology , skin biopsy
TX: Doxycycline
Comp: encephalitis, pulmonary edema, bleeding, shock
Syphilis
Type/Bug, Early congenital manifestation, Dx + Tx with stages, Reaction with treatment
Neurosyphilis (Sx, Dx)
Tabes dorsalis
Type: Spirochete
Bug: Treponema pallidum
Early Congenital features:
- Perinatal: Fetal demise, prematurity, low birth weight, focal necrosis of umbilical cord
- Mucocutaneous: snuffles, desquamating/maculopapular rash, fissures near orifices, jaundice
- MSK: Long bone abnormalities
- Reticuloendothelial: hepatosplenomegaly, lymphadenopathy, anemia, thrombocytopenia, leukopenia/leukocytosis
Dx:
- Nontreponemal (RPR, VDRL)
- Tremonemal (FTA-ABS)
Drugs
- Primary and Secondary: Benzathine Pen G IM (single dose)
- Latent (>12mo): Benzathine Pen G IM once weekly for 3 weeks
- Neuro/tertiary: Aqueous Pen G IV every Q4H for 10-14days
- Congenital: Aqueous Pen G IV Q8-12H for 10 days
- In pregnancy, if there is a penicillin allergy, the patient requires penicillin desensitization
Jarisch-Herxheimer reaction: acute febrile syndrome within 24hrs of treatement. No prevention, self-resolve within 48hrs. If severe, can be given acetaminophen.
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Neurosyphilis
- Asx at first –> HA, blurry vision
- Dx: LP
- Rapid plasma reagin titers >1:129
Tabes dorsalis
- Late neurosyphilis
- Years to decades after initial infection
- Involved posterior spinal column and nerve roots
Increased incidence/more rapid progression in HIV patients
Path: Treponema directly damages dorsal sensory roots
Sx:
- Neurogenic urinary incontinence
- Posterior column effects: Impaired vibration/proprioception, Sensory ataxia
- Nerve root effects: Lancinating pains (sharp, shooting, sudden)
- Associated with Argyll Robertson aka prostitute pupil
Tx: 10-14 days of IV aqueous penicillin G
Malaria
Carrier/Type/Bug + Drug
Why is P. Falciparum different
Something about vivax and ovale
Carrier: Mosquito
Type: Parasite
Bug: Plasmodium
Plasmodium falciparum: most severe because it can infect erythrocytes –> parasitemia. Erythrocytes form sticky membrane knobs –> bind to receptors on endothelial cells in capillaries and small venules –> partial vessel occlusion, inflammation, and organ dysfunction.
Plasmodium vivax and ovale form dormant hypnozoites in the liver
Drug:
Chloroquine (intraerythrocytic phase)
- Primaquine is aded for the dormant hepatic phase with vivax and ovale. Uses combo to prevent relapse
Viral meningoencephalitis
Bugs, Dx + Drugs
Bugs: Coxsackie (enterovirus) most common, HSV (herpes), West Nile (arbovirus)
Dx: LP –> CSF aseptic pleocytosis, viral serologies
Drug: supportive, Acyclovir for HSV, Vanco, 3rd gen cephalosporin empirically
UTI
Recurrent definition, Bugs, prevent, Dx, Tx, ppx, comp to pyelo and criteria for admission
Vaginitis (dx)
Recurrent definition: >2 in 6 months or >3 in 1 years
Pathogens: E.Coli (most common), Proteus mirabilis, Klebsiella pneumoniae
Prevent: genital hygiene, increased fluid intake, postcoital voiding, avoid spermicides
Dx:
- History alone (phone consultation) is usually sufficient for dx
- If seen in office: UA is sufficient
- PE is required for complicated cases (fever, chills, CVA tenderness, pregnant)
Tx:
- Non-pregnant: Nitrofurantoin, Trimethoprim-sulfamethoxazole (bactrim), Fosfomycin. If complicated, can used fluoroquinolone, CTX, Zosyn
- Pregnant: Nitrofurantoin & Trimethoprim-sulfamethoxazole (bactrim) (both only used in 2nd trimester) Amoxicillin-clavulante, Fosfomycin, Cefpodoxime
PPX: Nitrofurantoin, Trimethoprim-sulfamethoxazole (bactrim), and cephalexin
Comp: if progresses to pyelonephritis, patients can be treated with oral abx unless
1. Hemodynamically unstable
2. inability to tolerate oral medication (vomit)
3. Failure to improve with oral abx
4. Infant age <2mo d/t increase risk of sepsis
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Vaginitis
History alone is NOT reliable so patient should undergo pelvic exam examination and sample collection for testing.
HIV
Reporting guidelines
Pre treatment labs
Post-exposure guidelines
Rules before starting school
Oral candidiasis
PCP : CD#, Dx, Tx
Kaposi (association and cell type)
Primary CNS lymphoma (association, prognostic factors)
HIV-associated lipodystrophy (path, tx)
Physicians are required to report + HIV test to Department of Health but not always to the 3rd party (depends on the state)
Labs to obtain before starting treatment in newly dx patient:
- CD4 count, viral load, HIV genotype for staging and drug resistance.
- Testing for coinfection with Hep B (some meds can help treat both).
- Screen for TB, Hep C, STI’s
Post-exposure treatment:
- High risk (exposed to blood, semen, vaginal secretions, or any body fluids with visible blood): Urgent treatment with >3 drugs and continue for 4 weeks
- Low risk (exposed to urine, feces, nasal secretions, saliva, sweat, tears): ppx not recomended
School
- Recommended to attend school in a normal manner and participate in all sports. No requirement to disclose status to school.
Oral Candidiasis (scrapable lesion) that can raise suspicion for HIV.
Pneumocystis jirovecii pneumonia (PCP)
- CD4 <200
- Dx: Induced sputum cultures are accurate 50-90% of the time. Bronchiolar lavage is most accurate.
- Tx: Trimethoprim-sulfamethoxazole + Steroids.
Resp decompensation is common during first 2-3 days of tx d/t organism lysis –> inflammation. Steroids indicated if A-a gradient is >35 and PaO2 <70
Kaposi Sarcoma
- CD4 ~100
- strongly associated with HIV and HHV-8
- infects vascular and lymphatic endothelial cells –> differentiate into a mixed phenotype thought to increase oncogenic potential.
Primary CNS lymphoma
- Common malignancy in patients with advanced HIV infection
- Strongly related to EBV
- Usually associated with a significant degree of immunosuppression (persistently depressed CD4 count <50).
- Starting HAART therapy is associated with improved prognosis (with increased CD4 count and decreased viral load), because the degree of immunosuppression seems to be a major determinant of patient survival
HIV associated lipodystrophy
- Alteration of fat deposition
- Lipoatrophy: loss of subcutaneous fat from face, arms, legs, abdomen and/or butt
- Fat accumulation: dorsocervical “buffalo hump” and vascular abdominal fat accumulation –> increased abdominal girth (despite minimal subcutaneous abdominal fat)
- Abnormal lipid and glucose metabolism –> insulin resistance, dyslipidemia, and an increase risk of cardiovascular disease.
- Antiretrovirals can also cause dyslipidemia –> steatosis –> statin
- Statin
Chikungunya
Carrier/Bug, Sx, Tx
Carrier: Aedes mosquitoe :
Bug: Alphavirus
Sx: fever, joint pain, conjunctivitis, rash
Tx: supportive, chronic pain tx with MTX
Helminths
3 types, Sx, Comp, Labs,Dx,Tx
Ascaris lumbricoides (roundworm)
Trichuris trichiura (whipworm)
Ancylostoma duodenale or Necator americanus (hookworm from watching barefoot on the beach)
Sx: Pulmonary (cough, dyspnea), GI (N/V,abd pain, diarrhea)
Comp: Surgery if causes obstruction
Labs: Eosinophilia + fecal occult blood
Dx: O & P
Tx: Albendazole, Mebendazole is better for whip worms)
C. Diff
RF, 3 levels, Histo and Tx
RF: Antibiotics, Gastric acid suppression, Hospitalization, Age >65
3 levels:
- Nonsevere
- Severe: leukocytes >15,000 and creatinine >1.5
- Fulminant: severe with hypotension, ileus or megacolon, necrosis leading to perforation
Dx:
- Histo : yellow-white, patchy peseudomembranes, which consist of neutrophil-predominant inflammatory infiltrate, fibrin, bacteria and necrotic epithelium.
Tx:
- Nonsevere and severe: 10 days of Oral Fidaxomicin or Vancomycin. Oral Metronidazole 3rd line.
- Fulminant: Oral Vanco + IV Metronidazole
- Refractory: fecal transplant, surgical intervention
- NO STEROIDS
Erythema mulitform
Associated Bugs, Description
Associated infection: HSV, Mycoplasma pneumo
- Target lesions on skin: erythematous well-defined borders, with pale/dusky center that is often bullae/ulcerated
- Painful bullae or erosions on mucosa
- Not transmissible from person to person
Tx:
Acute: supportive, possible topical steroids
Recurrent: suppressive antiviral therapy
Animal bites
Oral flora of animal: Pasteurella or oral anaerobes
Skin flora: Strep pyogenes or Staph aureus
Bites with high risk of infection
- Crush injuries
- Bites on hands an feet
- Wounds on body >12hrs old or on face >24hrs old
- Cat and human bites (except on face)
- Bites wounds in immunocompromised hosts
**Wounds with high risk should be left open to heal by secondary intention except the face unless its >24hrs old **
HPV
Virus type, strands, Path
Genitat warts sx,tx
Plantar wart tx
Cervical cancer (4)
dsDNA
6 and 11 associated with genital warts (condylomata acuminata)
16 and 18 associated with cancer
Path: These oncogenes integrate in host genome and produced viral protein E6 and E7 which interact with p53 and Rb respectively –> inhibit cell cycle regulation
Genital warts (condyloma acuminata): pink, skin-colored hyperpigmented lesions. Smooth or cauliflower-like papules/nodules.
Transmission: sexual abuse, autoinoculation from other site, prenatal or perinatal
Sx: Usually asx, but can be pruritic and friable.
Dx:
- Turn white with application of acetic acid.
- if found in children, sexual abuse must be excluded
Tx:
- <1cm: imiquimod, cryotherapy, sinecatechins, podophyllotoxin, trichloroacetic acid.
- >1cm: excision, laser therapy, electrosurgery.
- recurrence is common
Plantar warts (with thrombosed capillaries)
Tx: Salicylic acid and cryotherapy , can take 1-2 months for resolution.
Shave or punch biopsy rarely needed.
Cervical cancer
- CIN 1 (low grade): dysplasia confined to lower 1/3 of cervical epithelium
- CIN 2/3 (high grade): no extending towards epithelial surface. Have a higher risk of progressing to invasive carcinoma.
- Invasive cell carcinoma: basement membrane invasion
- Cervical adenocarcinoma: atypical grandular cells invading BM
HHV-3
Genome make up, presentation, RF, Histo, contact precautions, Who is immune, Tx, postexposure tx, comp with tx
- dsDNA
- HHV-3 Varicella (chickenpox) Zoster (shingles )
- Zoster: unilateral dermatomal rash, crust over in 7-10 days
- RF: impaired cell mediated immunity like advanced age, immunosuppression (chronic steroid used), malignancy, liver/kidney disease.
- Hist: intranuclear inclusions in keratinocytes and multinucleated giant cells
Contact precautions:
- Local infection: standard precautions and lesion covering
- Disseminated infection: standard precautions + contact + airborne
- Not as infectious once crusted over
Management:
- Tx: 7 days course of ORAL VALACYCLOVIR
- Immune if previously had varicella or received varicella vaccine.
- If not immune: Varicella vaccine within 5 days
- Not immune, immunocompromised, pregnant or newborn: Immune varicella-zoster globulin within 10 days or antiviral therapy.
- Zoster vaccine only given if >50y/o
- Pain treatement: NSAIDs –> gabapentin, pregabalin, TCAs
Comp:
Disseminated herpes zoster infection; lesions outside primary or immediate adjacent dermatomes
Tx: hospitalization for IV acyclovir to decrease risk of ocular infection or encephalitis
Tetani
Bug/Type, Path, Sx, Prevention MOA
Clostridium tetani
Gram Positive rod
Anaerobic
Path: Produced neurotoxic exotoxin called tetanospasmin (tetanus toxin) that travels retrograde to CNS –> blocks inhibitory neurotransmission
Sx: increase muscle tone, lockjaw, painful spasms
MOA of vaccine: humoral antibody response against tetanus toxin
TB
Dx
Pleural effusion sx, fluid component, Dx
Tx active tv (with ae) and latent
Sx: Can cause a pleural effusion –> fever, cough, pleurisy and weight loss.
Thoracentesis can be positive for adenosine deaminase
Pleural fluid smear is normally aseptic so pleural biopsy is needed for diagnosis
Dx:
1. Screening test: Tuberculin skin test is generally positive in patient with active TB because lymphocytes recognize injected tuberculin antigens and trigger a strong type IV hypersensitivity response. However, ~25% of patients have false negative d/t impaired lymphocyte response –> minimal or no induration. False negative can also be seen in recent infection, immunocompromised, improper injection technique, or natural waning of immunity.
2. Interferon-gamma release assay
- NO false positives in patients with BCG vaccine
3. Patient with a history of latent TB will likely have positive skin and IGRA test for life, so they should get a chest xray.
4. Confirm test: sputum sample
Active TB
Symptomatic or radiographic findings require confirmation test as well
Tx
R - Rifampin (AE: GI, rash, red/orange body fluids, cytopenia)
I - Isoniazid (AE: Neurotoxicity - B6, hepatotoxicity)
P - Pyrazinamide (AE: Hepatotoxicity, hyperuricemia)
E - Ethambutol ( AE: optic neuropathy)
Latent TB Tx (no sx or xray findings):
- Rifampin daily for 4 month OR Rifampin + Isoniazid daily for 3 month OR Rifapentine + isoniazid weekly for 3 months.
- If Rifampin is not tolerated, Isoniazid monotherapy for 6-9 months can be used
TB meningitis
- eye exam: choroidal tubercles (yellow-white nodules near the optic disc)
- brain imaging: basilar meningeal enhancements
- CSF: elevated protein, Low glucose, lymphocyte pleocytosis, elevated adenosine deaminase
Dx: CSF for acid fast bacilli
Tx:
- prolonged tx for 2 months with 4 drugs (rifampin, isoniazid, pyrazinamide, and fluoroquinolone or injectable aminoglycosides)
- Followed by 9-12 months of continuation therapy (rifampin + isoniazid)
- Adjunctive steroids to reduce morbidity and mortality
HHV-4
Sx, Association, Dx (2), Tx (2)
EBV causing mononucleosis
Sx:
- Fever
- Fatigue
- Exudative pharyngitis or tonsillitis
- Lymphadenopathy (can be generalized)
- Hepatosplenomegaly
- Myalgia
- Weight loss, N/V due to hepatocellular inflammation
- Rash after amoxicillin
Association: Hodgkin lymphoma
Dx:
- Heterophile Ab (Monospot) which can be falsely negative during 1st week of illness
- Atypical lymphocytes are often seen on peripheral blood smear
Tx: supprotive care, HOWEVER steroids can be given when airway obstruction is severe
Parvovirus
Sx
Sx:
- Initially: Flu-like sx
- Yonger: slapped cheek rash, rarely arthralgia
- Adolescents and adults: acute onset symmetric joint pain, swelling, stiffness
- Erythematous lacy reticular rash
- Transient aplastic anemia
Chaga’s Disease
Type/Bug + Drug
Type: Protozoan
Bug: Trypanosoma cruzi
Sx:
- Biventricular heart failure (R>L) with cardiomegaly
- Ventricular apical aneurysm
- Mural thrombosis with embolic complications
- Fibrosis leading to conduction abnormalities (heart block and ventricular tachycardia)
- Progressive dilation of esophagus and colon
Aspergillus (Micro, Assoc, imaging, Dx, Tx)
Mucor/Rhizopus (micro, Ass, Dx, Tx
Aspergillus
- Micro :Monomorphic septate hyphae that branch at 45° Acute Angle
Allergic Bronchopulmonary aspergillosis
- Caused: exaggerated IgE and IgG mediated immune response to Aspergillus fungus.
- Associated with Asthma and CF
- Imaging: recurrently fleeting infiltrates & Bronchiectasis
- Dx: Positive Aspergillus skin test and/or IgE, elevated serum IgE and Eosinophilia
Tx: steroids +/ antifungal (itraconazole or voriconazole). Fluconazole has limited acidity against Aspergillus and is not 1st line.
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Mucor and Rhizopus
Micro: Irregular, broad, nonseptate hyphae branching at wide angles
Rhino-orbital-cerebral mucormycosis:
- Associated: DM, Hematologic malignancy, solid organ or stem cell transplant
Sx: Acute/aggresive. Fever, nasal congestion, purulent nasal discharge, HA, sinus pain, necrotic invasion of palate, orbit, brain
Dx: Sinus endoscopy with biopsy & culture
Tx: Surgical debridement, Liposomal amphotericin B, Elimination of risk factors
Botulism
RF, Path, Tx
Clostridium botulinum spores
RF: environmental dust/soil and honey
Path: Neurotoxin inhibits presynaptic Ach release into neuromuscular junction
Tx: Antitoxin therapy (botulism immuoglobulin), intubation if needed
Pertussis
Bug, Type, Drug
Bug: Bordetella pertussis (gram neg coccobacilli)
Major virulence factors: pertussis toxin (AB toxin), adenylate cyclase toxin, tracheal cytotoxin
Tx: Azithromycin which is only used to reduce transmission risk, doe not help with symptoms.
Tinea Versicolor
Sx, Dx, Tx
Bug: Malessezia furfur
Non-invasive fungal infection
More prominent in the summer
Inhibits pigmented transfer to keratinocytes and makes the affected skin paler
Pruritic
Dx: KOH showing hyphae and yeast
Tx: Ketoconazole, selenium sulfide, terbinafine, clotrimazole
Oral terbinafine or griseofulvin are ineffective
Pneumonia
Most common bug + drug
Preschool OR focal lung findings
Most common bug: Strep Pneumoniae
Tx: Amoxicillin
Older child OR well appearing with b/l lung findings
Most common bug: Mycoplasma Pneumoniae
Tx: Azithromycin
Comp: SIADH
Diphtheria
Toxigenic strains of Corynebacterium diphtheriae (gram neg bacillus)
Sx:
- Fever, malaise, sore throat
- Pharyngitis: grey patches/pseudomembrane (bleeds with scraping)
- Cervical lymphadenopathy
- Toxin-mediated damage to the heart (myocarditis), nervous system (neuritis), and kidney (kidney disease)
Dx:
- Cx from respiratory secretions
- Toxin assay (to prove toxigenic)
Tx:
- Erythromycin or Penicillin G
- Diphtheria antitoxin (if severe)
Cryptococcus neoforman
Bug, Sx, Drug
Encapsulated yeast
Acquired by inhalation
Primarily infects severely immunocompromised patients (AIDS with CD4 count <100/mm3)
Sx:
- Hepatosplenomegaly
- Umblicated skin lesions resembling molluscum contagiosum but develop central hemorrhage or necrosis
- Alveolar infiltrates
- Meningoencephalitis
Dx:
- Sputum culture growing yeast
- Positive serum cryptococcal antigen
- LP: to evaluate for CNS involvement
Tx: Amphotericin B + flucytosine followed by fluconazole
Giardiasis
Type of bug, RF, Pathogenesis, Sx, Dx, Tx, facts on transmission
Protozoan
RF:
- Fecal oral route
- Contaminated food and water
- Fecal incontinence & crowding (day care, nursing homes)
- Immunodeficiency
Pathogenesis:
- Villous blunting, disruption of epithelial high junctions, loss of brush border enzymes –> malabsorption
Sx:
- Subacute (<4 weeks) or chronic
- Loose oily non blood stools
- Bloating, flatulence
- Weight loss, decreased linear velocity, bit deficiency
Dx:
- Stool antigen or PCR testing
- Stool microscopy
Tx:
1st line: Tinidazole or nitazoxanide
Alternative: Metronidazole
Pregnancy (1st trimester): Paromomycin
- Refractory: evaluate for immunodeficiency
- Sx students with + stool culture do not need to refrain from school unless they are incontinent.
- Hand washing help students not pose a risk for transmission.
- Resistant to chlorination and remain viable
- Some exposed people become carriers (asx but + stool culture), and shed cysts in the stool for weeks-months
Cat scratch disease
Bugs, Sx, Dx, Drugs
Bug: Bartonella henselae, fastidious gram neg bacilli
Transmission: cat/kitten scratch/bite
Sx:
- Papular at scratch/bite site
- Regional adenopathy
- +/- fever of unknown origin >14 days
- Oculoglandular syndrome: conjunctivitis
Dx:
- Usual clinically
-Serology
Tx:
Generally self-limiting
- Azithromycin
Sporotrichosis
Bugs, Sx, Dx, Drugs
Sporothrix schenckii (dimorphic fungus)
Decaying plant matter/soil
Gardener, farmer, landscaper
Sx:
- Inoculation –> skin papules –> ulceration –> non purulent, odorless drainage
- Proximal lesions form along lymphatic chain (nodular lymphangitis)
- Distant spread & systemic symptoms are rare
Dx:
- Cultures showing cigar-shaped yeast with narrow base budding
Tx: Prolonged course of itraconazole
Influenza
High risk patients and Tx
- Age >65 y/o
- Pregnant women or up to 2 weeks postpartum
- Underlying chronic medical illness (pulmonary, cardiac, renal hepatic
- Immunosuppressed
- Morbidly obese
- Resident or nursing home or long-term care facility
Oseltamivir
- Used to reduce symptoms duration and potentially reduce risk of complications.
- If patient is not high risk, must be started before 48hrs of symptoms onset
- Can receive after 48hrs if patient requires hospitalization, has severe or progressive illness, is high risk
Neisseria gonorrhoeae
Type and Virulence factor
Intracellular organism
Gram - diplococcus that grows fastidiously
Virulence factors:
Binds to host epithelial cells using pili, proteinaceous projections on the outer surface of the bacteria. The pili undergo both phase variation (on-off expression) and antigenic variation (rapidly later antigenic profile of pills and limits long-lasting immunity.
Species that do not express bile are unable to bind to host cells and cause infection
Rabies
Most common vector are bats
If bitten by a domestic animal (dog), monitor the for 10 days for sx.
If no sx: no treatment
If sx: vaccine and immunoglobulin
If unable to monitor for 10 days: treat
