What is the most likely organism when cultures grew motile gram-negative rods in a case of severe diarrhea?

What is the most likely organism when cultures grew motile gram-negative rods in a case of severe diarrhea?

• A. Proteus vulgaris
• B. Salmonella typhi
• C. Yersinia enterocolitica
• D. E. coli

Answer: (D)

The most likely organism in cases of severe diarrhea, when cultures show motile gram-negative rods, is E. coli. E. coli, particularly enterotoxigenic and enterohemorrhagic strains, are well-known causes of diarrhea, especially in settings of foodborne outbreaks. This organism is prevalent in the gastrointestinal tracts of humans and animals, making it a common pathogen responsible for both non-bacterial and bacterial outbreaks of gastroenteritis. Its motility, due to flagella, aids in its pathogenicity by allowing for colonization and invasion of intestinal mucosa. While Proteus vulgaris is also a motile gram-negative rod, it is typically associated with urinary tract infections rather than gastrointestinal disease. Salmonella typhi, though it is motile and a significant cause of gastroenteritis, specifically causes typhoid fever and is less common in cases of acute diarrhea. Yersinia enterocolitica is also a potential cause of gastrointestinal symptoms and is motile at 25°C, but it is generally less common when compared to E. coli in severe diarrhea cases. Overall, the prevalence of E. coli as a common intestinal pathogen that fits the description of a motile gram-negative rod makes it the most likely

The most likely organism in cases of severe diarrhea, when cultures show motile gram-negative rods, is E. coli.

E. coli, particularly enterotoxigenic and enterohemorrhagic strains, are well-known causes of diarrhea, especially in settings of foodborne outbreaks. This organism is prevalent in the gastrointestinal tracts of humans and animals, making it a common pathogen responsible for both non-bacterial and bacterial outbreaks of gastroenteritis. Its motility, due to flagella, aids in its pathogenicity by allowing for colonization and invasion of intestinal mucosa.

While Proteus vulgaris is also a motile gram-negative rod, it is typically associated with urinary tract infections rather than gastrointestinal disease. Salmonella typhi, though it is motile and a significant cause of gastroenteritis, specifically causes typhoid fever and is less common in cases of acute diarrhea. Yersinia enterocolitica is also a potential cause of gastrointestinal symptoms and is motile at 25°C, but it is generally less common when compared to E. coli in severe diarrhea cases.

Overall, the prevalence of E. coli as a common intestinal pathogen that fits the description of a motile gram-negative rod makes it the most likely