STIS AND IMMUNOCOMPROMISED HOST

Question 1

Treatment of uncomplicated gonococcal infections of the cervix, urethra, and rectum

Answer 1

1. ceftriaxone 500 mg IM x1 (<150 kg)
2. ceftriaxone 1 g IM x 1 (>150 kg)
3. if chlamydia infection is not excluded - + doxycycline 100 mg PO BID x 7 days
4. if chlamydia infection is not excluded and pregnant - + azithromycin 1 g x 1
5. alternative if ceftriaxone not available:
   gentamicin IM x1 + azithromycin 2 g PO x 1
   cefixime 800 mg PO x 1
   -if chlamydia infection not excluded and treating with cefixime -> + doxycycline 100 mg PO BID x7 (azithromycin 1 g PO x 1 if pregnant)

Question 2

Treatment of uncomplicated gonococcal infections of the pharynx

Answer 2

1. ceftriaxone 500 mg IM x 1 (<150 kg)
2. ceftriaxone 1 g IM x 1 (>150 kg)
3. if chlamydia co-infection is identified - doxycycline 100 mg PO BID x 7 days (azithromycin 1 g PO x 1 if pregnant)
4. test-of-cure recommended 7-14 days after initial treatment, regardless of treatment regimen

Question 3

Treatment of syphilis: primary and secondary syphilis

Answer 3

1. benzathine Pen G 2.4 million units IM x 1

2. if allergic: doxy or tetracycline x 14 days

Question 4

Treatment of syphilis: early latent syphilis

Answer 4

1. benzathine Pen G 2.4 million units IM x 1 dose

2. pen-allergic: doxy or tetracycline x 28 days

Question 5

Treatment of syphilis: late latent or latent syphilis of unknown duration

Answer 5

1. benzathine Pen G 2.4 million units IM once weekly x 3 weeks
2. if pen-allergic: doxy or tetracycline x 28 days

Question 6

Treatment of syphilis: tertiary syphilis

Answer 6

1. benzathine Pen G 2.4 million units IM once weekly x 3 weeks
2. if pen allergic doxy or tetracycline x 4 weeks

Question 7

treatment of syphilis: Neurosyphilis

Answer 7

1. aqueous crystalline Pen G 304 million IV q4H x 10-14 days
2. alternative: procaine Pen G IM QD + probenecid PO QID x 10-14 days
3. may administer benzathine Pen G IM weekly for 3 weeks after completion of IV therapy
4. pen-allergic: ceftriaxone 2 g IM or IV daily x 10-14 days

Question 8

Treatment of syphilis: HIV

Answer 8

1. Primary and secondary syph: benzathine pen g IM x 1
2. early latent, late latent or syphilis of unknown duration:
   - early latent: benzathine pen G IM x 1
   - late latent or unknown: benzathine pen G IM once weekly x 3 weeks
3. neurosyphilis: same as non-HIV infected patient

Question 9

treatment of syphilis: pregnancy

Answer 9

penicillin is the only agent that reliably protects and treats the fetus; if pen allergic -> skin testing -> desensitization -> treat with penicillin regimen appropriate for their stage of infection

Question 10

Jarisch-Herxheimer reaction

Answer 10

• acute febrile reaction characterized by flu-like symptoms, HA, fever, chills, malaise, arthralgia, myalgia, tachycardia, peripheral vasodilation
• begins 2-4 hours after initiating therapy; may last 12-24 hours
• do not confuse with penicillin allergy
• more common in patients with early-stage syphilis (increased bacterial load)
• treat with antipyretics

Question 11

Treatment of chlamydia

Answer 11

doxycycline 100 mg PO BID x 7 days

-alternative regimen: levofloxacin 500 mg PO q24h for 7 days

Question 12

treatment of chlamydia: pregnancy

Answer 12

azithromycin 1 gram PO x 1

-alternative amoxicillin 500 mg PO TID x 7 days

Question 13

Treatment of genital herpes: first clinical episode

Answer 13

1. acyclovir 400 mg PO TID
2. Famciclovir 250 mg PO TID
3. Valacyclovir 1 g PO BID

treat for 7-10 days

Question 14

Treatment of genital herpes: regimens for episodic recurrent infections

Answer 14

1. acyclovir 800 mg PO BID for 5 days or 800 mg PO TID for 2 days
2. Famciclovir 125 mg PO BID for 5 days or 1 gram PO BID for 1 day
3. Valacyclovir 500 mg PO BID for 3 days or 1 gram PO QD for 5 days

Question 15

treatment of genital herpes: regimens for daily suppressive therapy

Answer 15

1. acyclovir 400 mg PO BID
2. Famciclovir 250 mg PO BID
3. Valcyclovir 500 mg PO QD or 1 gram PO QD

Question 16

Treatment of genital herpes: severe disease

Answer 16

acyclovir 5-10 mg/kg/dose IV q8h for 2-7 days or until clinical improvement is observed followed by oral therapy to complete at least 10 days

Question 17

Treatment of genital herpes: HIV

Answer 17

1. episodic infection: 
Acyclovir 400 mg PO TID
Famciclovir 500 mg PO BID
Valacyclovir 1 g PO BID
2. daily suppressive therapy: 
Acyclovir 400-800 mg PO BID or TID
Famciclovir 500 mg PO BID
Valacyclovir 500 mg PO BID

Question 18

Acyclovir resistant HSV treatment

Answer 18

foscarnet 40-80 mg/kg/dose IV q8h

cidofovir 5 mg/kg/kg IV once weekly

Question 19

Suppressive therapy in pregnant women with recurrent genital herpes

Answer 19

1. start at 36 weeks gestation
2. acyclovir 400 mg PO TID
3. Valacyclovir 500 mg PO BID

Question 20

Treatment of trichomoniasis

Answer 20

1. women: metronidazole 500 mg BID x 7 days
2. men: metronidazole 2 g PO x 1
3. alternatives: tinidazole 2 g PO x 1

• retest all sexually active women <3 months of initial treatment
• allergy to metronidazole -> desensitization
• avoid alcohol with metronidazole (24 hours) and tinidazole (72 hours)
• HIV positive: metronidazole 500 mg PO BID x 7 days

Question 21

Etiologic agents of PID

Answer 21

1. N. gonorrhoeae
2. C. trachomatis
3. vaginal flora (anaerobes, gardnerella vaginalis, gram (-) bacilli, S. alagactiae)
4. mycoplasma hominis, mycoplasma genitalium
5. ureaplasma urealyticum

Question 22

PID treatment

Answer 22

1. ceftriaxone 1 g IV Q24H + Doxycycline 100 mg IV or PO q12h + Metronidazole IV or PO q12h
2. Cefotetan 2 g q12h OR cefoxitin 2 g IV q6H + doxycycline 100 mg IV or PO q12h
3. alternative parenteral regimen:
   - unasyn 3 g IV q6h + doxycycline 100 mg IV/PO q12h
   - clindamycin 900 mg IV q8h + gentamicin
4. IM/Oral based: ceftriaxone IM x 1 + doxycycline PO AND metrodinazole PO q12h x 14 days

Question 23

Absolute neutrophil count (ANC)

Answer 23

ANC = WBC x (% polys + % bands)

Question 24

Common pathogens in immunocompromised host infections

Answer 24

1. bacteria: S. aureus, S. epidermidis, streptococci, enterococci, E. coli, K. pneumoniae, psuedomonas
2. fungi: candida, aspergillus, zygomycetes (mucor, rhizopus)
3. viruses: HSV

Question 25

Defects in T-lymphocyte and macrophage function (cell-mediated immunity)

Answer 25

• result in reduced ability of the host to defend against intracellular pathogens
• common pathogens:
  1. bacteria: listeria, nocardia, legionella, mycobacteria
  2. fungi: C. neoformans, candida, histoplasma capsulatum
  3. viruses: CMV, VZV, HSV
  4. fungi: pneumocystis jiroveci

Question 26

defects in B-cell function (humoral immunity)

Answer 26

-common bacterial pathogens (encapsulated) - S. pnuemoniae, H. influenzae, N. meningitidis

Question 27

bacteremic episodes in cancer patients are due to___

Answer 27

gram (+) cocci

Question 28

primary risk factor for aspergillus spps infections

Answer 28

prolonged neutropenia

Question 29

Low risk: anticipated neutropenia <7 days, clinically stable, no medical comorbidities, and outpatient fever onset

Answer 29

1. outpatient: oral FQ + augmentin

2. inpatient: zosyn, antipseudomonal carbapenem (not erta), cefepime, ceftazidime

Question 30

high risk: anticipated neutropenia > 7 days, clinically unstable, any medical comorbidities, HSCT, or inpatient at fever onset

Answer 30

1. zosyn, antipseudomonal carbapenem (not erta), cefepime, ceftazidime -add vancomycin for cellulitis, pneumonia, severe sepsis or shock, gram + bacteremia, suspected IV catheter infection
   - for septic shock, gram - bacteremia, or pneumonia: add aminoglycoside or antipseudomonal FQ (cipro, levo)

Question 31

Management of antimicrobial therapy after initiation of empiric therapy for an immunocompromised host

Answer 31

1. re-evaluate the clinical status of the patient after 48-72 hours of empiric antimicrobial therapy
2. addition or modification to the initial regimen may be required, especially in patients with ANC <500/mm3 for > 1 week

• if MRSA - consider addition of van, linezolid, or dapto
• if VRE - consider early addition of linezolid or dapto
• if ESBL producer- consider early use of a carbapenem
• if KPC producer- consider ceftazidime/avibactam =, meropenem/vaborbactam, imipenem/cilstatin/relebactam

Question 32

Antifungal therapy for immunocompromised hosts

Answer 32

1. begin empiric therapy in neutropenic patients who remain febrile with undocumented infection after 4-7 days of broad-spectrum antibiotics (if duration of neutropenia is expected to be >7 days)
2. antifungal treatment options:
   - amphotericin B or liposomal amphotericin
   - azoles: fluconazole, itraconazole, voriconazole, isavuconazole, posaconazole
   - echinocandins
3. continue antifungal therapy for 2 weeks in the absence of signs and symptoms of active fungal disease

Question 33

The most important determinant of patient outcomes in immunocompromised hosts

Answer 33

resolution of neutropenia

Question 34

Prophylaxis of Infections in neutropenic cancer patients

Answer 34

1. reverse isolation with strict adherence to infection control guidelines
2. laminar airflow rooms to reduce the risk of airborne pathogens
3. FQ prophylaxis should be considered in moderate to high-risk patients with expected prolonged and profound neutropenia (ANC <100/mm3 for >7 days) - cipro or levo. If pt develops breakthrough infection during FQ prophylaxis, avoid FQ-based empiric antibiotic regimen
4. antifungal prophylaxis: azoles (fluconazole, itraconazole, voriconazole, posaconazole), echinocandins (capsofungin and micafungin)
5. bactrim reduces risk for P. jiroveci pneumonia
6. anti-viral prophylaxis: acyclovir for HSV, annual influenza vaccine with inactivated vaccine, varicella vaccine