A female presents with leaking and meconum stained liquior at 32 weaks. She is infected with
“Discolored brownish or meconium stained amniotic fluid is common with fetal infection, even with preterm gestation”
Hence, the correct answer is Listeria, rest of the infections do not lead to preterm labour with meconium stained liquor.
Listeriosis

Causative organism- listeria monocytogenes (facultative intracellular gram positive bacillus)
Mode of infection- Food-borne infection caused by eating food like raw vegetables, Coleslaw, Apple cider, Melons, Milk, Fresh mexican style cheese, Smoked fish, Processed foods.

Clinical features

Can be asymptomatic
Can cause febrile illness.

Maternal complications which can occur due to listeria infection are:

Preterm labor,
Chorioamnionitis,
Menonium stained liquor,
Abortions,
Placental Macroabscesses

Maternal infection can lead to fetal infection characterised by:

Disseminated granulomatous lesions with microabscess in skin
Stillbirth
Overall perinatal mortality-50%.

Management

Drug of choice is combination of Ampicillin + gentamicin or in case of pencillin allergy – Trimethoprim sulfamethoxazole
Maternal treatment may be effective for fetal infection
There is no vaccine for listeriosis.
CMV
Listeria
Toxoplasma
Herpes