Members of the Family Enterobacteriaceae

Citrobacter Resembles Salmonella but are ONPG (+) & LDC (-) Citrobacter species freundii (UTI, pneumonia, intraabdominal abscess) diversus (neonatal meningitis) amalonaticus (extraintestinal infections) C. freundii S. diversus H2S + - Indole - + KCN + -

Klebsiella Klebsiella -Enterobacter-Serratia-Hafnia K. pneumoniae >Friedlander’s bacilli (encapsulated and mucoid) > (+) String test Klebsiella aerogenes is associated with hospital acquired infections of wounds and of the urinary tract K. rhinoschleromatis – rhinoscleromatis (granulomatous disease of the nose and pharynx with intense swelling and malformation of the entire face and neck)

The patient's K. pneumoniae isolate was string test positive (>5 mm string length).

LABORATORY DIAGNOSES Specimens: Depending on the site of infection, specimens include urine, pus, sputum and infected tissue. Morphology Klebsiellae are Gram negative, non-motile, usually capsulated rods. Culture Klebsiellae are aerobes and facultative anaerobes. Blood agar: Klebsiellae produce large grey white usually mucoid colonies. MacConkey agar and CLED medium: Most klebsiellae are lactose-fermenting, producing mucoid pink colonies on MacConkey agar and yellow mucoid colonies on CLED medium K. rhinoscleromatis is non-lactose fermenting. Biochemical tests Klebsiellae are indole negative, ornithine decarboxylase negative and do not produce H2S.

Klebsiella on CLED medium show yellow lactose fermenting colony Klebsiella on Macconkey medium show large mucoid pink lactose fermenting colony

Enterobacter -species: habitat: soil, water, dairy products -normal flora of the gut of animals & humans -motile, ODC & ONPG (+) LDC ADH ODC Urease Yellow pigment E. cloacae - + + V - E. aerogenes + - + - - E. gergoviae + - + + - E. sakazakii - + + - + E. taylorae - + + - -

Enterobacter

Edwardsiella Edwardsiella tarda (human pathogen – bacteremia and wound infection) hoshinae (snakes, birds and water) ictaluri (enteric septicemia in fish)

Serratia opportunistic pathogens DNAse, lipase, gelatinase S. marcescens S. liquefaciens S. rubidaea S. oderifera

Serratia

Proteus Tow important species , P. mirabilis and P. vulgaris Morphology Proteus is actively motile with peritricous flagella , non capsulate, Gram negative pleomorphic rods. Rapid urease producers Swarming, burned chocolate odor

Proteus with peritricous flagella

Pathogenicity P. mirabilis causes: 1- Urinary infections. in the elderly and young males and often following catheterization or cystoscopy.. 2- Abdominal and wound infections 3- secondary invader of ulcers, burns and damaged tissues. 4- Septicaemia 5- Meningitis and Chest infections.

is electrolyte deficient Biochemical tests Culture aerobically, most Proteus cultures have a characteristic ‘fishy’ Odour and Swarming on the medium MacConkey, CLED, XLD media: non-lactose fermenting colonies after overnight incubation at 35–37 ºC Swarming is prevented on MacConkey agar and XLD agar because these media contain bile salts. Swarming is inhibited on CLED agar because it is electrolyte deficient Biochemical tests Do not ferment lactose. Rapidly hydrolyze urea (within 4 hours), early screening test in differentiating enteric pathogens, e.g. salmonellae and shigellae from Proteus. Phenylalanine deaminase (PDA), positive. Indole negative (P. vulgaris is indole positive).

Proteus P. mirabilis P. vulgaris Indole - + ODC + - Fermentation Maltose - + Xylose + + Salicin - + Chloramphenicol S R

Proteus P. mirabilis P. vulgaris Indole ……… ……. Maltose ……… ……. Xylose …….. ……. Salicin …….. ……. Chloramphenicol …….. ……

Proteus Proteus McConkey Urease test

Swarming on Blood agar Swarming pehomenon

Morganella Formerl known as Proteus M. morganii – only specie UTI’s and wound infections

Providencia Providencia ( 4 species – P. alcalifaciens, P. Rustigianii, P. rettgeri, P. stuartii) P. rettgeri P. stuartii Urease + - Citrate + +

Yersinia 11 species Y. pestis (plague) – bipolar staining (wayson) Agent of bubonic plague, pneumonic and septicemic plagues Bubonic – bite of infected flea Pneumonic Prefered growth at 25 deg C Y. enterocolitica (acute enteritis – appendictis like) Pig, cats and dogs Cold enrichment Motile at RT Y. pseudotuberculosis Pathogen in animals (turkey, geese, doves, farm and domestic animals)

Yersinia Yersinia pestis Safety pin appearance

Revision Question 1- Characteristic of enterobacterceae all of the following except : a- Gram negative rod b- Facultative anaerobic c- Ferment glucose d- Oxidase positive 2-Sworming is special characteristic of: a. Pseudomonades b- Proteus c- E. coli d- Klebsiella 3- Mucoid colony is special characteristic of:  

4- Bacteria which give green metallic sheen on EMB medium is: a. Pseudomonades b- Proteus c- E. coli d- Klebsiella 5- Polysaccharide capsule present on which of the following bacteria: c- Shigella 6- Which of the following bacteria is urease positive : 7- Which of the following bacteria is lactose fermenter:

When we inoculate members of enterobacterceae on MacConkey agar, mention which organism grow producing lactose fermentor colony and which grow producing lactose fermentor colony

الهم لا تجعل الدنيا اكبر همنا و لا مبلغ علمنا klebsiella and e.coli الهم لا تجعل الدنيا اكبر همنا و لا مبلغ علمنا