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Vertical Transmission of Salmonella typhi

Author Information

Poonia S*, Satia MN**, Torame VP***, Natraj G****.
(* Third Year Resident, ** Prodessor, Department of Obstetrics and Gynecology; *** Assistant Professor, **** Professor, Department of Microbiology; Seth GS Medical College & KEM Hospital, Mumbai, India.)

Abstract

A case of typhoid fever in second trimester of pregnancy with vertical transmission leading to intrauterine fetal death at 14 weeks of gestation has generated curiosity about organisms that cross placenta in pregnancy. Salmonella typhi was isolated in the retained products of conception which were sent for culture and sensitivity as patient presented with symptoms and signs of pelvic infection.

Introduction

Typhoid fever is a major health problem in developing countries. Cases of vertical transmission have been reported from India.[1][2]Pregnant women are susceptible to food  borne infections like typhoid owing to hormonal changes that suppress immunity.[3]Salmonella typhi can cross the placenta and cause miscarriage, still births and preterm labor. We report a case where a Para 1 Living 1 with history of fever and inevitable abortion grew Salmonella typhi on her retained products of conception.

Case Report

A 22 year old Gravida 2 Para 1 Living 1 woman with 14 weeks of gestation came with pain in abdomen and spotting per vaginum since one day. She had history of fever off and on one week back, for which she had taken antibiotics from a private practitioner, the details of which were not available. She had registered at 6 weeks of gestation and pregnancy was confirmed by ultrasonography. She had a fever spike of 380 C after admission. Her vital parameters were stable.  On abdominal examination, her uterus was corresponding to 14 weeks of gestation. Bimanual pelvic examination showed the uterus to be corresponding to 14 weeks, cervical os was open and products of conception felt were through it. Vagina was warm and uterus was tender. Based on history, clinical findings, and geographical endemicity of acute onset fever pathogens, her blood samples were sent. Her hemoglobin was 9.4 g/dL, white blood cell count 7300/cmm, and platelets of 0.66/cmm. Her urine culture was sterile. Widal titre was positive up to dilution of 1: 240 for both Salmonella typhi ‘O’ (somatic) and Salmonella typhi’ H’ (flagella). Rapid test for malaria, dengue and leptospirosis were negative. Liver and renal function parameters were within normal limits. Blood sugars and thyroid profile were normal. A curettage was done for inevitable and septic abortion under antibiotic cover (ceftriaxone and metronidazole). Products of conception were sent for culture and sensitivity. Salmonella typhi was isolated from products of conception and further confirmed by Salmonella polyvalent antisera.
Salmonella typhi was sensitive to ceftriaxone, carbapenems, other third generation cephalosporins, cotrimoxazole and chloramphenicol. The isolate was a nalidixic acid resistant Salmonella Typhi (NARST) which was also resistant to ciprofloxacin. Her blood culture and stool culture sent on day 3 of admission, did not reveal any Salmonella growth. She was treated with same antibiotics for 5 days and was discharged on day 5 of procedure.
In the absence of any other likely cause of spontaneous miscarriage in this case, Salmonella typhi was presumed to be the most likely cause.

Discussion

Incidence of infection with Salmonella in pregnant patients is similar to general population (0.2%).[4] Typhoid is caused by Salmonella enterica serotype typhi. The most common route of transmission is feco-oral route. In humans young, old, pregnant, HIV infected and patients who have undergone transplant are at higher risk for Salmonella infection.[5] Vertical transmission of Salmonella occurs via transplacental spread or because of the bacteraemia during labor or due to inadvertent fecal contamination of birth canal. Incidence of fetal loss in untreated typhoid can be as high as 80%.[4] Salmonella typhi has been associated with abortions in animals like sheep, cattle and horses.[6]
Salmonella typhi is an intracellular bacterium that resides within the modified phagosomes of Antigen Presenting cells (APCs). Innate immunity is important in curtailing infection during the first week of infection and CD4 T-cells response to Salmonella typhi is detectable only after 7 days of infection whereas CD8 T-cells response is delayed until second week post infection.[7] Overall, Salmonella typhi has evolved many mechanisms to evade the host immune system. In pregnancy, there is a shift in immune status from type 1 (cell mediated immunity) to type 2 (humoral immunity).This shift in immune system though is more pronounced at the maternal fetal interface and may also affect systemic immunity.[8]
Various organism other than TORCH (Toxoplasma gondii, Rubella virus, Cytomegalovirus, Herpes Simplex virus) that infect human placenta have been reported in literature.[9] These organisms are intracellular for a portion of their lifetime and infect placenta via hematogenous spread. Salmonella being an intracellular organism are recruited at the fetal implantation site early in illness before treatment or during an episode of bacteremia. The extravillous trophoblast with immune modifications are juxtaposed near these maternal decidual cells. Due to various invasive and evasive strategies Salmonella typhi may cause significant damage to mother and fetus.
As per reports by Hick’s and French, Salmonella typhi may cross placenta and cause miscarriage (65-80%), stillbirths and preterm labour.[10] Transplacental transmission usually presents as spontaneous second trimester abortion without premature rupture of membranes. Neonates born to mother with Salmonellosis are more prone to severe complications like septicaemia and meningitis.[11]
Ampicillin or amoxicillin are considered as first line drugs during pregnancy. Ceftriaxone is the preferred drug in nalidixic acid resistant Salmonella typhi (NARST), also resistant to ciprofloxacin.[12] Typhoid vaccines (both polysaccharide and live vaccine) are category C drugs during pregnancy.
Salmonellosis is usually not included in the differential diagnosis of miscarriage, stillbirth or neonatal sepsis that occur during pregnancy. However it should be considered to prevent fetal and mother morbidity.

References
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Citation

Poonia S, Satia MN, Torame VP, Natraj G. Vertical transmission of Salmonella typhi. JPGO 2015. Volume 2 No. 1. Available from: http://www.jpgo.org/2015/01/vertical-transmission-of-salmonella.html