OBGYN: infections

Urinary tract infections

Antibiotics for UTIs

  1. Ceftriaxone [Rocephin®] (IV) — used for hospitalized patients to treat pyelonephritis. Always hospitalize pregnant women with pyelonephritis. After 2 days of no fever (clinical improvement) can switch to oral medication to continue treating pyelonephritis. Remember, pyelonephritis requires 5-14 days of antibiotics to eliminate bacteria from the entire urinary tract (kidney, renal collecting ducts, bladder). 
  2. Cephalexin [Alcephin®, Keflex®] (oral) — safe in pregnancy. 
  3. Fosfomycin [Monuril®] (oral) — safe in pregnancy
  4. Nitrofurantoin (oral) — used for cystitis only, does not achieve enough concentration in kidneys to treat pyelonephritis.
  5. Trimethoprim-sulfamethoxazole [Bactrim®] (oral) — used for cystitis only, does not achieve enough concentration in kidneys to treat pyelonephritis. Avoid in 3rd trimester near term because of risk of neonatal kernicterus. 
  6. Ciprofloxacin [Ciprobay®] — avoided in pregnancy because its fetal effects are not well studied. 

Sexually transmitted infections

Neisseria gonorrhoeae gonococci —> Sexually or perinatally transmitted.

  • Si/Sx: causes gonococcal urethritis/cervicitis, septic arthritis, neonatal conjunctivitis (2-5 days after birth), PID, and Fitz-Hugh-Curtis sydnrome.
  • Diagnosis: NAAT.
  • Treatment: IM ceftriaxone [Rocephin®] single 250mg dose. Add oral azithromycin [zithromax®] single 1 g dose for non-gonococcal (chlamydia) STD treatment — most patients have both at the same time; so unless excluded by diagnostic testing, treat for both. Prevention: condoms reduce sexual transmission; erythromycin eye ointment prevents neonatal blindness.

Chlamydia trachomatis Types D—K –> cause neonatal conjunctivitis (1-2 weeks after birth), neonatal pneumonea, nongonococcal urethritis/cervicitis, PID, ectopic pregnancy, reactive arthritis.

  • Dx: for urethritis/cervicitis treat empirically while awaiting culture because of high risk of complications. Also while waiting for results, empiric treatment should cover both Neisseria gonorrhea (ceftriaxone) and chlamyida (doxycycline or azithromycin if pregnant).
  • Tx: non-pregnant: DC = doxycycline for chlamydia. If pregnant, AC = azithromycin [zithromax®] for chlamydia. “AC and DC = azithromycin or doxycycline for chlamydia”

Trichomonas vaginalis (Trichomoniasis) —> flagellated protozoan infection spread by sexual contact and is responsible for 1/4 cases of vaginal inflammation (vaginitis) in women.

  • Si/Sx: often aysmptomatic (up to 50%) especially men. Men may present with urethritis or prostatitis. Women present with vaginal discharge (profuse, foul-smelling, yellow-green or grey and frothy) along with pruritis, dysuria and dyspareunia.
  • Diagnosis: wet mount (motile parasites, pH ≥4.5, many WBC and infalmmatory cells, may have positive whiff test), antigen detection, culture. Urine PCR in males.
  • Treatment: metronidazole [Flagyl®] for patient and partner(s) even if asymptomatic. PO Metronidazole 2g singe dose is effective. But can give it over 7 days, 500mg bid. Symptomatic pregnant women should get the single 2g oral dose. Warn patients to not take with alcohol. Alternatives: Tinidazole, single 2g dose.

Gardnerella vaginalis —> Bacterial vaginosis. Tx: metronidazole or tinidazole. Tinidazole 2 g once daily for two days or 1 g once daily for five days.

Treponema pallidum —> Syphilis. Treatment: Penicillin G (IM) for all stages, except that in tertiary syphilis, give intravenous penicillin G. Single dose for primary and secondary.

  • Pregnant with Syphilis —> Tx: penicillin G. If allergic, desensitize and treat with penicillin.
  • Primary syphilis (Chancre) —> Tx: a single dose of IM penicillin G; alternative if severe allergy in non-pregnant patients is doxycycline for 14 days.
  • Secondary syphilis (diffuse rash) —> Tx: a single dose of IM penicillin G; alternative if severe allergy in non-pregnant patients is doxycycline for 14 days.
  • Latent syphilis (asymptomatic) —> Tx: 3 doses of IM penicillin G. Alternate if allergic is doxycycline x 28 days. 
  • Tertiary syphilis (gummas, cardiac) —> Tx: IV penicillin G x 14 days. If allergic but have neurosyphilis, desensitize and give penicillin. If allergic and no neurosyphilis, give ceftriaxone x 14 days. 
  • Jarisch-Herxheimer reaction (flu-like illness with fever, chills, headache, and myalgia after antibiotics are started due to sudden release of bacterial antigens) seen with treatment of other spirochete illnesses too. Seen in ~10-35% of patients treated for early syphilis. Spirochetes release large quantities of lipoproteins as they die. Reaction starts <12 hours after starting antibiotic and resolves spontaneously within 48 hours. Symptoms can include worsening of syphilitic rash (diffuse, macular, including palms and soles) in secondary syphilis. Tx: supportive (IV fluids, acetaminophen, NSAIDs). 
  • Congenital syphilis —> classic triad of clear rhinorrhea, desquamating rash on palms or soles and may be seen on buttocks and other areas, and long bone abnormalities on x-ray. Tx: penicillin G. Late complications: saddle nose, Hutchinson teeth, saber shins. 

Toxoplasma gondii —> a widely prevalent intracellular protozoan.

  • Asymptomatic —> Some immunocompetent individuals, including pregnant women, are asymptomatic with infection.
  • Flu-like syndrome —> seen in healthy immunocompetent individuals. Pregnant women, typically have this mild presentation, whereas their fetuses get the more severe congenital toxoplasmosis. Presentation: similar to mononucleosis — fever, lymphadenopathy, myalgias, and/or diffuse non-pruritic maculopapular rash that resolves spontaneously. Diagnosis: rule out mononucleosis by finding a negative heterophile antibody test. Confirm toxoplasmosis with serology or PCR.
  • Transmission: most often ingestion of cysts in meat (contaminated and undercooked) but can also be from unwashed produce. Can also be acquired via oocytes in cat feces (eg contaminated kitty litter) or cross the placenta. Cats are the definitive host of the toxoplamsa oocytes, and pregnant patients should avoid cats. Causes mononucleosis like symptoms in healthy (immunocompetent) individuals, encephalitis in immunocompromised individuals, and congenital toxoplasmosis in the fetus.
  • Diagnosis: get appropriate sample and do either toxoplasma serology (IgA or IgM) or PCR test.
  • Treatment: first line is Sulfadiazine + Pyrimethamine. Add folinic acid for congenital toxoplasmosis.


Ceftriaxone — 3rd generation cephalosporin (broader-spectrum so it covers more gram negative bacteria). Only 1% is bioavailable if given orally, so typically used intramuscularly (IM) or intravenously (IV). Brand: Rocephin®