What species of bacteria is part of normal flora but can cause infection in neonates?

Escherichia coli is considered a part of the normal flora of the gastrointestinal tract in humans, including neonates. While it typically exists harmlessly within the gut, certain strains can become pathogenic under specific conditions, particularly in vulnerable populations such as neonates. Premature infants or those with compromised immune systems are at a higher risk for infections caused by these pathogenic strains. These infections can lead to conditions like sepsis, meningitis, or necrotizing enterocolitis, all serious complications that require immediate medical attention.

Listeria monocytogenes, while also known to cause infections particularly in pregnant women and neonates, is not a standard component of the normal flora. Campylobacter jejuni is primarily associated with foodborne illnesses and is not a part of the normal flora in healthy individuals. Clostridium difficile generally colonizes the intestines following antibiotic use and is more associated with colitis than with being part of typical flora in healthy neonates.