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 The most important bacterial family in human medicine  Well-defined diseases with typical clinical symptoms:  Typhoid fever, dysentery and plague.

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Presentation on theme: " The most important bacterial family in human medicine  Well-defined diseases with typical clinical symptoms:  Typhoid fever, dysentery and plague."— Presentation transcript:

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2  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

3  41 genera with hundreds of species  Gram-negative, facultatively anaerobic rod  Natural habitat: intestinal tract of humans and animals

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

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6  The most important pathogenicity factors:  Colonizing factors  Invasins  Endotoxin  Exotoxins  Enterobacteriaceae are the most significant contributors to intestinal infections

7  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

8  O antigens: Somatic antigens (polysaccharide)  H antigens: Flagellar antigens (protein)  K antigens: Capsular antigens (carbohydrate)  e.g., serovar O18:K1:H7

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12  Intestinal tract of humans and animals  indicator organism for fecal contamination of water and foods

13  Extraintestinal infections  Intestinal infections (Diarrhoeal diseases)

14  Urinary tract infections  Wound infections  Peritonitis  Cholecystitis  Appendicitis  Sepsis and endotoxin induced shock  Neonatal meningitis

15  Enteropathogenic E. coli (EPEC)  Enterotoxigenic E. coli (ETEC)  Enteroinvasive E. coli (EIEC)  Enterohaemorrhagic E. Coli (EHEC)  Enteroaggressive E. coli (EaggEC)

16  Frequently cause diarrhea in infants  Vomiting, fever and prolonged diarrhoea  Infants mainly  Many serotypes

17  Enterotoxins that cause watery diarrhoea similar to cholera  Infants and adults  Traveler diarrhea  Many serotypes

18  Cause a dysentery like infection of the large intestine (similar to shigellosis)  Fever and colitis  Many serotypes

19  Produce verocytotoxins and cause a hemorrhagic colitis (damage to vascular endothelia )  Causes life-threatening haemorrhagic diarrhoea  All ages

20  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

21  Chronic watery diarrhoea  Mainly in children

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26  Four subspecies:  K.p. pneumoniae  K.p. aerogenes  K.p. ozaenae  K.p. rinhoscleromatis

27  UTI  Wound infections  Chest infections

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30  P. mirabilis  UTI  Wound infection  Septiceamia  Occasionally meningitis and chest infections  P. vulgaris  UTI and wound infections

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32  Enterobacter  Citrobacter  Serratia  Opportunistic pathogens:  UTI  Wound infections  Septiceamia  Pulmonary infections

33  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

34  Midstream urine  Bacterial count  CFU/ml  ≥10 5 /ml indicate an infection  10 4 /ml doubtful significance  ≤10 3 /ml indicate a contamination

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37 Oxidase test


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