**Question:** In a 6 months old baby, floppy infant syndrome is seen commonly due to infection with –

A. Group B Streptococcus (GBS)
B. Cytomegalovirus (CMV)
C. Herpes Simplex Virus (HSV)
D. Respiratory Syncytial Virus (RSV)

**Core Concept:** Floppy infant syndrome (FIS) is a clinical syndrome characterized by poor muscle tone, hypotonia, and feeding difficulties in neonates and infants. It can be caused by various infections, which can affect the central nervous system (CNS) and lead to neurological dysfunction.

**Why the Correct Answer is Right:**

GBS (Group B Streptococcus) is a common cause of sepsis and meningitis in newborns, including preterm infants. Neonatal GBS infection can lead to systemic inflammation, resulting in hypotonia and neurological dysfunction, which is characteristic of floppy infant syndrome.

**Why Each Wrong Option is Incorrect:**

- CMV (Cytomegalovirus): Although CMV can cause neurological complications, it typically presents with a combination of symptoms and may not exclusively present as floppy infant syndrome.
- HSV (Herpes Simplex Virus): Herpes simplex virus infections are usually caused by neonatal herpes, presenting with skin lesions, encephalitis, or meningitis, but not exclusively as floppy infant syndrome.
- RSV (Respiratory Syncytial Virus): Respiratory syncytial virus infection mainly affects respiratory system leading to respiratory distress, cough, and wheezing, not presenting as floppy infant syndrome.

**Why Option A is Right:**

GBS (Group B Streptococcus) is a common cause of sepsis and meningitis in newborns, including preterm infants. Neonatal GBS infection can lead to systemic inflammation, resulting in hypotonia and neurological dysfunction, which is characteristic of floppy infant syndrome.

**Clinical Pearl:** Early diagnosis and treatment of GBS infection are crucial to prevent complications and improve outcomes in newborns presenting with floppy infant syndrome.

**Why Each Wrong Option is Incorrect:**

- CMV (Cytomegalovirus): Although CMV can cause neurological complications, it typically presents with a combination of symptoms and may not exclusively present as floppy infant syndrome.
- HSV (Herpes Simplex Virus): Herpes simplex virus infections are usually caused by neonatal herpes, presenting with skin lesions, encephalitis, or meningitis, but not exclusively as floppy infant syndrome.
- RSV (Respiratory Syncytial Virus): Respiratory syncytial virus infection mainly affects the respiratory system leading to respiratory distress, cough, and wheezing, not presenting as floppy infant syndrome.