A Rare Presentation of Salmonella typhi Meningitis in a Seven Month Old Infant

Introduction

Salmonella typhi causes enteric or typhoid fever and is a major public health concern in the developing as well as developed countries. Despite being a common infection, S. typhi remains a rare cause of meningitis in children. The earliest case of Salmonella meningitis was described by Tomkins in 1881.¹ Further, a few cases were described by Cole in 1904 and also by Bayne Jones in 1917. Only a few cases were reported after these, making it a rare condition. A wide array of treatment options have been used with variable success. We describe a case of typhoid meningitis in a 7 month old infant.

Case Presentation

A developmentally normal and nutritionally well grown seven month old, male infant was brought with complaint of fever for past 20 days, responding to antipyretics with intermittent afebrile periods. Vomiting was present for two days prior to admission along with decreased oral intake and reduced activity. No history of loose motions or convulsions was noted. Child was immunised according to the Indian Academy of Paediatrics schedule till age; however, typhoid vaccine was not given.

On examination, infant was febrile, lethargic and refused to feed. Pallor was present. The anterior fontanel was slightly bulging and was pulsatile. Terminal neck stiffness was present. Erythematous rash was present over the face. Heart sounds were normal. Examination of chest and abdomen was normal.

Provisional differential diagnosis included meningitis, incomplete Kawasaki disease and also post-Covid Multisystem Inflammatory Syndrome in children (MIS-c). Complete Blood Count (CBC) showed haemoglobin 5.7 gm/dL, White Blood Cell (WBC) 53,930 U/L (neutrophils predominant) and platelets of 960,000 thou/mL. C-reactive protein (CRP) was 83 mg/L and Erythrocyte sedimentation rate (ESR) 58 mL at the end of 1 hr. N-terminal pro b-type natriuretic peptide (NT Pro BNP) was 2500 (pg/mL), 2D Echo was suggestive of dilated coronaries with a Z score of 2.05 for left main coronary artery (LMCA), 3.40 for left anterior descending (LAD) and 3.29 for right coronary arterial (RCA). IL-6 level was 352.7 pg/mL.

Cerebrospinal fluid (CSF) showed protein 94 mg/dL, sugar 5 mg/dL (simultaneous blood sugar of 273 mg/dL) and neutrophilic pleocytosis (total nucleated cells were 9610/mm³ of which 90% were neutrophils and 10% lymphocytes).

Injection Ceftriaxone 100 mg/kg/day was started. The child was treated with Intravenous Immunoglobulin (IVIG) 2 gm/kg for incomplete Kawasaki disease and with intravenous methyl prednisolone 10 mg/kg, keeping in mind post Covid MIS-c. The infant received packed red blood cell transfusion in view of low haemoglobin. The child’s fever and irritability improved.

After 24 hours of hospitalization, blood and CSF culture showed growth of Non-lactose fermenting organism. Routine biochemical test showed that the strain was motile and produced trace amounts of Hydrogen sulfide (H₂ S) on Triple Sugar Iron (TSI) slant. Identification and antimicrobial susceptibility test were performed on Vitek 2 Compact. The isolate was identified as Salmonella typhi. Identification was confirmed by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) and serotyping. Injection Ceftriaxone 100 mg/ kg/day was started. In view of the same, steroids were stopped.

The clinical condition including irritability, bulging fontanelle improved. The child became afebrile within three days of starting antibiotics. Repeat CSF analysis was done after seven days of antibiotics which showed decrease in the protein levels (72.3 mg/dL) and total nucleated cell count (167/mm³ ) and no growth in cultures was observed after five days of incubation suggesting clearance of infection from the CSF.

In view of pallor, iron studies were performed which showed presence of iron deficiency anaemia; hence, iron supplements were added. His Covid PCR, antibody status was non-reactive. Ceftriaxone at 100 mg/kg/day was given for 28 days. The infant was discharged after the completion of antibiotic schedule with no further complications.

Subsequent reports after three months revealed no evidence of sickle cell disease (normal Hb-electrophoresis) and normal brain stem auditory evoke potential.

Discussion

Salmonella typhi is a gram negative bacillus belonging to the family of Enterobacteriaceae. It is a known cause of enteric fever in both the developed and the developing countries. It is a facultative intracellular organism.

The route of infection is mainly feco-oral. Bacteraemia can lead to various complications almost involving any organ, mainly the bones and the meninges.

CNS involvement is not a common feature of Salmonella infection and can occur in forms of typhoid encephalopathy, meningitis, focal abscess, seizures. It can also lead to upper motor neuron disease.^2,3

Correct diagnosis of Salmonella typhi meningitis is of prime importance as it needs to be treated for prolonged duration of minimum 21-28 days,^2,4 once the repeat culture is negative. Inadequate treatment duration is known to result in relapse or progression of the disease and is associated with long term neurological sequelae.

At presentation, the child was very sick and clinically there were possibilities of post Covid multisystem inflammatory disease, atypical (incomplete) Kawasaki disease which can also present in similar manner. MIS-C can have devastating clinical outcome and hence once coronary dilatation was seen on echocardiogram, IVIG and methyl prednisolone treatment was initiated. However, subsequently when cultures grew gram negative organisms, these treatments were unnecessary and may even be harmful; hence were stopped within 24 hours of initiation.

Salmonella typhi meningitis is a serious and rare presentation of Salmonella typhi infection. A timely diagnosis and early adequate treatment prevents devastating neurological consequences in children. 

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Conflict of interests

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