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Updated: Jul 5, 2025
Author Spotlight: Advancements in Understanding and Combatting Shigella Infections
Published on: February 9, 2024
Shigella as a Cause of Diarrhea Hospitalization in Children Under Five: Evaluation by Conventional and Molecular
Pallavi Bansal1, Dheeraj Shah1, Rajesh Kumar Meena1
1Pediatrics, University College of Medical Sciences, Delhi, IND.
Insights
Shigella infection in young children often presents as watery diarrhea, not bloody diarrhea. Molecular methods like PCR are more effective than stool culture for diagnosing Shigella, which is frequently missed by conventional tests.
Area of Science:
- Pediatric Infectious Diseases
- Microbiology
- Molecular Diagnostics
Background:
- Shigella is a significant cause of diarrhea in children under five.
- Conventional laboratory methods often fail to detect Shigella infections.
- Bloody stools, a common indicator, are absent in many Shigella cases.
Purpose of the Study:
- To determine the frequency of Shigella detection using molecular and conventional methods in young children.
- To analyze the clinical profile and outcomes of children with Shigella diarrhea.
- To evaluate the diagnostic performance of PCR versus conventional methods for Shigella.
Main Methods:
- A prospective observational study involving 150 children under five with acute diarrhea.
- Stool samples were analyzed using microscopy, culture, and DNA extraction for PCR.
- PCR targeted the ipaH gene sequence for specific Shigella detection.
Main Results:
- Shigella was detected by PCR in 8.7% of children, compared to 0.7% by culture.
- PCR showed significantly higher sensitivity than stool culture (7.7%) and blood in stools (15.4%).
- Most Shigella-positive cases (11/13) presented with non-bloody diarrhea; no significant clinical predictors were identified.
Conclusions:
- Watery diarrhea is the predominant presentation of Shigella infection in children, making blood in stools an unreliable diagnostic marker.
- Stool PCR offers superior diagnostic performance for Shigella compared to conventional stool culture.
- Molecular diagnostics are crucial for accurate Shigella detection in pediatric diarrhea cases.
Background And Objectives:
Shigella is an important cause of diarrhea in children under five, often missed by conventional laboratory methods. Blood in stools has always been a syndromic indicator for Shigella diarrhea, but most cases present with watery diarrhea without blood. This study aimed to determine the frequency of Shigella detected by molecular and conventional methods in children under five. Additionally, we aimed to study the clinical profile and outcome of children with Shigella diarrhea managed as per current diarrhea treatment guidelines.
Methods:
In this hospital-based prospective observational study, stool samples from 150 children (age range: one month to five years) with acute diarrhea (duration < seven days) were subjected to routine microscopic examination, stool culture, and DNA extraction. The extracted DNA from stored stool samples was subjected to polymerase chain reaction (PCR) amplification using a specific primer for the invasion plasmid antigen H gene sequence (ipaH) gene at 424 bp. Results were interpreted in the context of the percentage of isolation of Shigella by molecular (PCR) and conventional methods (stool microscopy and culture) and the follow-up outcome in terms of recurrence of diarrhea or dysentery and growth faltering over three months after discharge.
Results:
Shigella infection was diagnosed in stool samples by PCR from 13 (8.7%) children, whereas it was isolated by conventional stool culture in only one (0.7%) child. The sensitivity of culture was only 7.7% against PCR for the diagnosis of Shigella infection, whereas blood in stools had a sensitivity of 15.4%. The majority of Shigella PCR-positive cases (11 out of 13) presented with non-bloody diarrhea. None of the evaluated clinical predictors had a significant association with the Shigella infection. No statistically significant difference was found between PCR-positive and PCR-negative children at the end of follow-up (P>0.05).
Conclusion:
The majority of children with Shigella infection present with watery diarrhea rather than bloody diarrhea, and a history of blood in stools is a poor marker for the diagnosis of shigellosis. The diagnostic performance of stool culture is also very low compared to stool PCR for the diagnosis of Shigella diarrhea.
