Enterobact Summary:
1. Definition and classification of enterobacteria
Enterobacteriaceae are a large family of Gram-negative, rod-shaped, facultative aerobic,
motile or nonmotile bacteria capable of fermenting glucose and commonly found in the
human and animal digestive tract. They are classified into several genera, including
Escherichia, Salmonella, Shigella, Klebsiella, Enterobacter, Proteus, Serratia, etc.
2. General characteristics
Morphology: Gram-negative bacilli, sporeless, with or without capsule.
Metabolism: Fermentation of glucose, reduction of nitrates to nitrites, catalase positive,
oxidase negative.
Habitat: Present in the environment (water, soil), but especially in the digestive tract of
humans and animals.
3. Pathogenicity factors
They have several virulence mechanisms:
Adhesion factors (fimbriae or pili) facilitating their attachment to host cells.
Production of toxins such as enterotoxins (e.g. Shigella toxin) and endotoxins
(lipopolysaccharides – LPS).
Secretion systems: Type III (T3SS) allowing the injection of proteins into the host cell.
4. Associated pathologies
Enterobacteriaceae can be responsible for various infections:
Intestinal infections: Diarrhea (enterotoxigenic Escherichia coli), dysentery (Shigella), typhoid
fever (Salmonella Typhi).
Urinary tract infections: Uropathogenic Escherichia coli (UPEC).
Lung infections: Klebsiella pneumoniae.
Septicemia and meningitis: Escherichia coli K1 in newborns.
5. Bacteriological diagnosis
The diagnosis is based on:
Culture on specific media: MacConkey (lactose +/-), Hektoen (H2S +/-).
Biochemical tests: Indole, urease, mobility, sugar fermentation.
Serology: Search for Ag O, H, K for Salmonella and others.
Molecular biology: PCR for detection of specific genes.
1. Definition and classification of enterobacteria
Enterobacteriaceae are a large family of Gram-negative, rod-shaped, facultative aerobic,
motile or nonmotile bacteria capable of fermenting glucose and commonly found in the
human and animal digestive tract. They are classified into several genera, including
Escherichia, Salmonella, Shigella, Klebsiella, Enterobacter, Proteus, Serratia, etc.
2. General characteristics
Morphology: Gram-negative bacilli, sporeless, with or without capsule.
Metabolism: Fermentation of glucose, reduction of nitrates to nitrites, catalase positive,
oxidase negative.
Habitat: Present in the environment (water, soil), but especially in the digestive tract of
humans and animals.
3. Pathogenicity factors
They have several virulence mechanisms:
Adhesion factors (fimbriae or pili) facilitating their attachment to host cells.
Production of toxins such as enterotoxins (e.g. Shigella toxin) and endotoxins
(lipopolysaccharides – LPS).
Secretion systems: Type III (T3SS) allowing the injection of proteins into the host cell.
4. Associated pathologies
Enterobacteriaceae can be responsible for various infections:
Intestinal infections: Diarrhea (enterotoxigenic Escherichia coli), dysentery (Shigella), typhoid
fever (Salmonella Typhi).
Urinary tract infections: Uropathogenic Escherichia coli (UPEC).
Lung infections: Klebsiella pneumoniae.
Septicemia and meningitis: Escherichia coli K1 in newborns.
5. Bacteriological diagnosis
The diagnosis is based on:
Culture on specific media: MacConkey (lactose +/-), Hektoen (H2S +/-).
Biochemical tests: Indole, urease, mobility, sugar fermentation.
Serology: Search for Ag O, H, K for Salmonella and others.
Molecular biology: PCR for detection of specific genes.
