Infectious Disease Flashcards
Osteomyelitis best initial test, best second-line test, most accurate test
Best initial test: Plain X-ray; Best second-line test (if there is high clinical suspicion and x-ray is negative): MRI; Most accurate test: MRI
Osteomyelitis treatment
M.S.S.A: Oxacillin or Nafcillin IV x 4-6 weeks
M.R.S.A: Vancomycin, Linezolid, Daptomycin
GRAM (-) BACILLI: (salmonella & pseudomonas): treated with oral antibiotics; confirm is gram-negative bone biopsy, organism must be sensitive to antibiotics
Otitis externa: cause, testing, treatment
Cause: Swimming (washes out normal acidic environment), foreign objects (Qtips, hearing aids)
Testing: P/E, do not perform culture
Tx: Topical antibiotics (ofloxacin, polymyxin/neomycin), hydrocortisone (decrease swelling/itching), acetic acid & water solution (to reacidfiy the ear, can help eliminate infection)
Malignant Otitis Externa: cause, best initial test, most accurate test, treatment
Cause: osteomyelitis of skull from psuedomonas in diabetic pt.
Initial test: Skull X-ray or MRI; Accurate: Biopsy
Tx: Surgical debridement + antibiotics active against psuedomonas (cipro, piperacillin, cefepime, carbapanem, aztreonam)
Otitis media: Key features, Testing, Treatment
Redness, Bulging, Decreased hearing, loss of light reflex, Immobility of tympanic membrane
Testing: P/E
Best initial therapy: Amoxicillin 7-10 days (longer for younger pts, shorter for older pts)
Most accurate test: tympanocentesis/aspirate of tympanic membrane only if failed tx/persistent
Sinusitis: Features, Cause, Testing, Tx
Nasal discharge, headache, facial tenderness, tooth pain, bad taste, transillumination of sinus
Cause: Mostly viral; bacterial same as Otitis Media (S. pneumonia MCC, H.influenza, M. Catarrhalis)
Best initial: X-ray; Most accurate: Sinus aspirate for culture (more accurate than CT or MRI)
Tx: Same as for otitis media + inhaled steroids
Use Amox if: -Fever & pain - Persistent symptoms despite 7 days of decongestants and -Purulent nasal discharge
Pharyngitis: Key features, Testing, Tx
Diagnosis of streptococcal diagnosis is certain if the following is present:
-Pain/Sore throat -Exudate in pharynx -Adenopathy in neck -No cough/hoarseness
Testing: “Rapid strep test” (positive test is as specific as throat culture & determines if organism is group A strep). If (-), no further testing or abx
Tx: Penicillin or Amoxicillin;
Pen allergy: Azithromycin or Clarithromycin
What can streptococcal (group A strep) pharyngitis lead to?
Rheumatic Fever or Glomerulonephritis
Influenza (“the flu”): Features, Testing/next best step, Tx
Arthralgia, Myalgia, Cough, Headache, Fever, Sore throat, Tiredness
Testing/Next best step: Viral antigen detection of nasopharyngeal swab
Tx: >/=48 hrs: Osetlamivir (tamiflu) or Zanamivir - neuraminidase inhibitors against A/B
>48 hrs: symptomatic tx (rest, hydration, antipyretics, analgesics)
What are the strongest indications for vaccination against influenza? is the flu vaccine required for Ages 19-64? Ages 65+?
COPD, CHF, Dialysis, Steroid use, Healthcare workers, Age 50+
Ages 16-64: Every Year; Ages 65+: Every Year
Pneumococcal vaccination (S.pneumonia; pneumonia, meningitis, sepsis, etc): Recommendation for Ages 19-65? 65+?
19-64: 1 or 2 doses for high risk pts
65+: 1 dose
Tetanus, Diptheria, Pertussis (Td/Tdap) vaccination recommendations for Ages 19-64? 65+?
19-64: Tdap once as substitute for Td booster, then Td every 10 yrs.
65+: Tdap once as substitute for Td booster, then Td every 10 yrs.
Rabies Vaccination:
What are the two types?
Previously vaccinated person re-exposed? Previously unvaccinated person exposed?
(1) Rabies immune globulin for passive immunization (2) Rabies vaccine for active immunization
Previously vaccinated person re-exposed :
only active w/rabies vaccine
Previously unvaccinated person exposed:
both active and passive immunization
Impetigo: cause, testing, treatment
Cause: S. pyogenes, S. Aureus
Testing: Look for weeping, crusting, oozing of skin
Tx:
Mild disease: Topical agents - Mupirocin or Retapamulin
Severe disease: Oral agents - Dicloxacillin or Cephalexin
CA-MRSA: TMP/SMZ, Clindamycin
Penicillin allergy–
Rash: Cephalosporins are safe.
Anaphylaxis: Clindamycin
Severe infection with anaphylaxis: Vancomycin, Telavancin, Linezolid, Daptomycin
Erysipelas: Cause, Features, Best Initial Tx
Cause: Group A streptococcal infection of the skin
Features: bright red, hot, swollen lesion, well-demarcated lesion on face
Best initial tx: Oral Dicloxacillin or Cephalexin
If confirmed group A streptococci: Penicillin K
Cellulitis: Risk factors, Cause, Features, Testing, Tx
Risk factors: IV drug use, DM, IC, Obesity
Cause: S. aureus = S. pyogenes
Features: warm, red, swollen, tender skin
Testing: If on leg –> Lower extremity Doppler
Tx: Minor disease: Dicloxacillin or cephalexin orally
Severe disease: Oxacillin, nafcillin, Cefazolin IV
Penicillin allergy: Use cephalosporins (Cefazolin)
Anaphylaxis/severe: Vanc, Linezolid, Daptomycin
Anaphylaxis/minor: Macrolides or Clindamycin
Folliculitis<Boils –
Cause, Testing, Tx
Cause: S. Aureus
Testing: Based on appearance
Tx: For larger infections (boils) - drainage;
Antibiotic therapy is identical to cellulitis –
Minor disease: Dicloxacillin or cephalexin orally
Severe disease: Oxacillin, nafcillin, Cefazolin IV
Penicillin allergy: Use cephalosporins (Cefazolin)
Anaphylaxis/severe: Vanc, Linezolid, Daptomycin
Anaphylaxis/minor: Macrolides or Clindamycin
What can pts with skin infections develop? And not develop?
Can develop post-streptococcal glomerulonephritis
Cannot develop rheumatic fever
Fungal infections: Presentation of Tineas? Tinea capitis? Tinea Unguium/Onychomycosis?
Tineas: Pruritic, erythematous, scaly plaques with central clearing
Capitis: Itching of scalp, dandruff, bald patches
Unguium: Nails may be thickened, yellow, cloudy, fragile or broken
Fungal infections: Best initial test, Most accurate test
Best inital test: KOH preperation
1) Scrape skin or nail
2) Place scraping on slide with KOH prep & acid & heat it
3) Epithelial cells will dissolve and leave fungal forms behind, visible on slide
Most accurate test: Fungal culture
Fungal infections: Treatment:
Topical antifungal medications (if not hair/nails):
Clomitrazole, miconazole, ketoconazole, econazole, terconazole, nystatin, ciclopirox
Oral antifungal meds (hair/nail involvement):
Terbinafine: Increased LFTs, must monitor
Itraconazole
Griseofulvin (for tinea capitis): has less efficacy than terbinafine or itraconazole
S/e of Terbinafine?
Increased LFTS
Fungal infections: body, hand, foot, groin, scalp, nail beds
Tinea corporus = body, manus = hand, pedis = foot, cruris = groin, capitis = scalp, unguium/onychomycosis = nail beds
Urethritis: Features, Cause, Testing, Treatment
*Urethral discharge +/- dysuria (burning, urgency, frequency); Cause: chlamydia, gonorrhea
Testing: Urethral swab for Gram stain, WBC count, culture, DNA probe, Nucleic acid amplification
(Single best test for chlamydia/gonorrhea)
Tx: 2 medications due to coinfection risk; drug active against gonorrhea & against chlamydia
–Gonorrhea meds: Ceftriaxone IM, Cefpodoxime oral, Ciprofloxacin oral (2nd line), Ceftriaxone IM (pregnant pts)
–Chlamydia meds: Azithromycin (single dose), Doxycycline (1 week), Azithromycin (pregnant pts)
Urethritis & Cervicitis: Treatment
–2 medications; 1 active against chlamydia, 1 active against gonorrhea.
–Gonorrhea meds: Ceftriaxone IM, Cefpodoxime oral, Ciprofloxacin oral (2nd line), Ceftriaxone IM (pregnant pts)
–Chlamydia meds: Azithromycin (single dose), Doxycycline (1 week), Azithromycin (pregnant pts)
Disseminated gonorrhea features
Polyarticular disease, Petechial rash, Tenosynovitis (inflammation of fluid filled sheath/synovium that surrounds tendon)
If Chlamydia is untreated, what can it lead to?
Infertility
If pt develops recurrent episodes of gonorrhea, what should he be tested for?
Terminal complement deficiency: predisposes pt to recurrent episodes of Neisseria (any form; genital & CNS)
Cervicitis: Features, Testing, Treatment
Cervical discharge/inflamed “strawberry” cervix
Testing: (Same as for urethritis) Urethral swab for Gram stain, WBC count, culture, DNA probe, Nucleic acid amplification
(Single best test for chlamydia/gonorrhea)
Tx: (Same as for Urethritis) 2 medications due to coinfection risk; drug active against gonorrhea & against chlamydia
–Gonorrhea meds: Ceftriaxone IM, Cefpodoxime oral, Ciprofloxacin oral (2nd line), Ceftriaxone IM (pregnant pts)
–Chlamydia meds: Azithromycin (single dose), Doxycycline (1 week), Azithromycin (pregnant pts)
Pelvic Inflammatory Disease (PID): Features, Testing: Measure of severity, Best initial, Most accurate, Treatment
Lower abdominal pain, tenderness, fever, cervical motion tenderness (pain upon pelvic exam)
Testing: no specific blood tests
Measure of severity: Leukocytosis
Best initial test: pregnancy test then cervical culture then DNA probe for chlamydia/gonorrhea
Most accurate test: Laparoscopy (rarely needed)
Tx:
–Outpatient: Ceftriaxone (IM), Doxycycline (oral)
–Inpatient: Ceftoxin or Cefoxitin (IV) and Doxycycline and maybe Metronidazole
Single best test for chlamydia/gonorrhea:
Nucleic Acid Amplification (NAAT): DNA probe;
can be done on voided urine in men and blind vaginal swab in women
What is the most important thing to do in a women with lower abdominal pain or tenderness?
Exclude ectopic pregnancy; perform urine pregnancy test first and then get a cervical culture and start therapy
What antibiotics are safe in pregnancy?
Penicillins, Cephalosporins, Aztreonam, Erythromycin, Azithromycin
Epididymo-Orchitis: Features, Treatment
Epidydymis: connects testicle to vas deferens (transports sperm; infection spread to testicles)
–Extremely painful & tender testicle with a normal position in the scrotum (vs testicular torsion: elevated testicle in abnormal transverse position)
Tx: < 35 years: Ceftriaxone and Doxycycline
>35 years: Fluoroquinolone
General features of Ulcerative Genital Diseases
- Associated with enlarged lymph nodes (inguinal adenopathy)
- -Sexual history is not as important as the presence of ulcers
Chancroid: Cause, Features, Testing, Treatment
Haemophilus ducreyi – highly contagious, rare, tropic areas, gray base, foul odor
Best initial test: Swab for Gram stain (gram negative coccobacilli) and culture (requires specialized medium: Nairobi or Mueller-Hinton)
Tx: Single IM shot Ceftriaxone or
Single Oral dose of Azithromycin
Lymphogranuloma Venereum (LGV): Cause, Features, Testing, Treatment
Chlamydia L1-L3 – developing nations; Large tender nodes (inguinal adenopathy –> swelling –> buboes –> possible draining sinus tract) + Ulcer
Testing: Diagnose with serology for Chlamydia Trachomatis (complement fixation titers in blood)
Tx: Aspirate bubo, treat with Doxycycline or Azithromycin
HSV2/Genital Herpes: Features, Testing, Treatment
Vesicles prior to ulcer + painful
Testing: Tzanck Prep IF roofs come off vesicles and lesion becomes ulcer of unclear etiology
Tx: Valacyclovir/Acyclovir/Famciclovir x 7-10 days
(Acyclovir safe in pregnancy; use if active lesions @ 36 weeks)
What is Tzanck prep?
Test done in HSV2 if roofs come off vesicles and lesion becomes unclear etiology; Scraping of ulcer to look for Tzanck cells (multinucleated giant cells)
Syphilis: Pathogen, Presentation, Most accurate test in Primary syphilis
–Treponema Pallidum
–Painless, firm genital lesion, painless inguinal adenopathy
Most accurate test in primary syphilis: Darkfield microscopic exam (swab lesions);
more sensitive than VDRL & RPR in primary - only 75%, false negative rate of 25%
Primary Syphilis: Symptoms, Testing, Treatment, Jarisch-Herxheimer reaction
Painless Chancre, Adenopathy Initial test: Darkfield, then VDRL/RPR Tx: Single IM shot penicillin; Penicillin allergic - Doxycycline Jarisch-Herxheimer Reaction: Fever, headache, myalgia developing 24 hrs after treatment for early stage syphilis; benign, self-limited reaction caused by release of pyrogens from dying treponemal. Treat with aspirin and continue treatment.
Jarisch-Herxheimer Reaction
Jarisch-Herxheimer Reaction: Fever, headache, myalgia developing 24 hrs after treatment for early stage syphilis; benign, self-limited reaction caused by release of pyrogens from dying treponemal. Treat with aspirin and continue treatment.
Secondary Syphilis: Symptoms, Testing, Treatment
Rash, mucous patch, Alopecia areata, Condyloma Lata
Initial test: RPR & FTA
Tx: Single IM shot penicillin;
Penicillin allergic - Doxycycline
Tertiary Syphilis: Symptoms, Testing, Treatment
Neurological involvement: Tabes dorsalis, Argyll-Robertson pupil, general paresis, rarely a gumma or aortitis
Initial test: RPR & FTA, Lumbar Puncture for neurosyphilis (test CSF w/VDRL & FTA). CSF VDRL is only 50% sensitive.
Tx: IV penicillin; Desensitize if penicillin allergic
What is the treatment for neurosyphilis or syphilis in pregnant patient if pts are penicillin allergic?
Desensitize
