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Enterobacteriaceae. Enterobacteriaceae. The most important bacterial family in human medicine Well-defined diseases with typical clinical symptoms: Typhoid fever, dysentery and plague Nosocomial infections: Urinary tract infections, pneumonias, wound infections and sepsis.

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Enterobacteriaceae

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Enterobacteriaceae1
Enterobacteriaceae

  • The most important bacterial family in human medicine

  • Well-defined diseases with typical clinical symptoms:

    • Typhoid fever, dysentery and plague

  • Nosocomial infections:

    • Urinary tract infections, pneumonias, wound infections and sepsis


Definition and significance
Definition and significance

  • 41 genera with hundreds of species

  • Gram-negative, facultatively anaerobic rod

  • Natural habitat: intestinal tract of humans and animals


Enterobacteriaceae

The Most Important Genera/Species/Vars of Enterobacteriaceae and the Corresponding Clinical Pictures


Virulence and pathogenicity
Virulence and pathogenicity and the Corresponding Clinical Pictures

  • The most important pathogenicity factors:

    • Colonizing factors

    • Invasins

    • Endotoxin

    • Exotoxins

  • Enterobacteriaceae are the most significant contributors to intestinal infections


Identification of enterobacteriaceae
Identification and the Corresponding Clinical Picturesof Enterobacteriaceae

  • Gram-negative rod

  • Usually motile (with few exceptions)

  • Facultative anaerobes

  • Grow on simple nutrient media

  • Oxidase test negative

  • Ferment glucose with acid or acid and gas


Sero typing based on antigenic structure
Sero and the Corresponding Clinical Pictures-typing based on antigenic structure

  • O antigens: Somatic antigens (polysaccharide)

  • H antigens: Flagellar antigens (protein)

  • K antigens: Capsular antigens (carbohydrate)

  • e.g., serovar O18:K1:H7


Escherichia coli klebsiella and proteus
Escherichia coli Klebsiella and the Corresponding Clinical Pictures and Proteus


Escherichia coli
Escherichia coli and the Corresponding Clinical Pictures


Enterobacteriaceae

Escherichia coli on and the Corresponding Clinical PicturesChromID CPS agar


Natural habitat
Natural habitat and the Corresponding Clinical Pictures

  • Intestinal tract of humans and animals

  • indicator organism for fecal contamination of water and foods


Infections
Infections and the Corresponding Clinical Pictures

  • Extraintestinalinfections

  • Intestinal infections (Diarrhoealdiseases)


Extraintestinal infections
Extraintestinal and the Corresponding Clinical Pictures infections

  • Urinary tract infections

  • Wound infections

  • Peritonitis

  • Cholecystitis

  • Appendicitis

  • Sepsis and endotoxin induced shock

  • Neonatal meningitis


Diarrheagenic pathovars
Diarrheagenic and the Corresponding Clinical Picturespathovars

  • EnteropathogenicE. coli (EPEC)

  • EnterotoxigenicE. coli (ETEC)

  • EnteroinvasiveE. coli (EIEC)

  • EnterohaemorrhagicE. Coli (EHEC)

  • EnteroaggressiveE. coli (EaggEC)


Enterobacteriaceae
EPEC and the Corresponding Clinical Pictures

  • Frequently cause diarrhea in infants

  • Vomiting, fever and prolonged diarrhoea

  • Infants mainly

  • Many serotypes


Enterobacteriaceae
ETEC and the Corresponding Clinical Pictures

  • Enterotoxins that cause watery diarrhoea similar to cholera

  • Infants and adults

  • Traveler diarrhea

  • Many serotypes


Enterobacteriaceae
EIEC and the Corresponding Clinical Pictures

  • Cause a dysentery like infection of the large intestine (similar to shigellosis)

  • Fever and colitis

  • Many serotypes


Enterobacteriaceae
EHEC and the Corresponding Clinical Pictures

  • Produce verocytotoxins and cause a hemorrhagic colitis (damage to vascular endothelia )

  • Causes life-threatening haemorrhagicdiarrhoea

  • All ages


Enterobacteriaceae
EHEC and the Corresponding Clinical Pictures

  • No pus cells and no fever

  • It can progress to Haemolytic Uremic Syndrome → Renal failure

  • O157:H7 or verocytotoxin-producing E. coli

  • Contaminated meat products, unpasteurized milk and diary products


Eaggec
EaggEC and the Corresponding Clinical Pictures

  • Chronic watery diarrhoea

  • Mainly in children


Klebsiella species
Klebsiella and the Corresponding Clinical Pictures species


Enterobacteriaceae

Klebsiella and the Corresponding Clinical Pictures species


Klebsiella pneumoniae
Klebsiella and the Corresponding Clinical Picturespneumoniae

  • Four subspecies:

    • K.p.pneumoniae

    • K.p. aerogenes

    • K.p. ozaenae

    • K.p. rinhoscleromatis


Infections caused by klebsiella species
Infections caused by and the Corresponding Clinical PicturesKlebsiellaspecies

  • UTI

  • Wound infections

  • Chest infections


Proteus species
Proteus and the Corresponding Clinical Pictures species


Enterobacteriaceae

Proteus and the Corresponding Clinical Picturesspecies on Blood Agar


Medically important proteus species
Medically important and the Corresponding Clinical PicturesProteus species

  • P. mirabilis

    • UTI

    • Wound infection

    • Septiceamia

    • Occasionally meningitis and chest infections

  • P. vulgaris

    • UTI and wound infections


Other enterobacteria
Other and the Corresponding Clinical Picturesenterobacteria


Other enterobacteria1
Other and the Corresponding Clinical Picturesenterobacteria

  • Enterobacter

  • Citrobacter

  • Serratia

  • Opportunistic pathogens:

    • UTI

    • Wound infections

    • Septiceamia

    • Pulmonary infections


Laboratory diagnosis
Laboratory diagnosis and the Corresponding Clinical Pictures

  • Specimens:

    • Urine, pus, faeces, CSF, blood, sputum

  • Direct examination:

    • Gram –ve bacilli

    • Few capsulated

  • Culture aerobically at 36-37° C:

    • Blood agar

    • MacConkey agar

    • CLED

    • XLD and DCA


Enterobacteriaceae
UTI and the Corresponding Clinical Pictures

  • Midstream urine

  • Bacterial count

  • CFU/ml

    • ≥105/ml indicate an infection

    • 104/ml doubtful significance

    • ≤103/ml indicate a contamination


Enterobacteriaceae

MacConkey and the Corresponding Clinical Pictures agar showing lactose and non-lactose fermenting colonies


Enterobacteriaceae

Escherichia coli (Gram negative) and the Corresponding Clinical Pictures


Enterobacteriaceae

Oxidase and the Corresponding Clinical Pictures test


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