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Unit 4 Chapter 19

Enterobacteriaceae

QuestionAnswer
key characteristics of the Family Enterobacteriaceae gram-negative, non-spore-forming, faculatively anaerobic bacilli; can appear as coccobacilli or as straight rods; can produce large mucoid colonies, large moist, gray colonies
Enterobacteriaceae *virulence factors* ability to adhere, colonize, produce toxins, and invade tissue; some species harbor plasmids that can provide antimicrobial resistant genes; produce plasmid-mediated extended spectrum β-lactamase
Enterobacteriaceae *antigenic factors* O antigen, H antigen, K antigen
E. coli *colony morphology* motile, generally possess adhesive fimbriae and sex pili and O, H, and K antigens; usually appears as a lactose-positive colony with a surrounding area of precipitated bile salts on MAC agar, green metallic sheen on EMB, facultatively anaerobic
E. coli *gram stain results* gram-negative rods
E. coli *testing results* fermentation of glucose, lactose, trehalose, and xylose; production of indole from tryptophan; glucose fermentation by the mixed acid pathway: methyl red positive and Voges-Proskauer-negative; does not produce H2S, DNase, urease, orphenylalanine deaminase
E. coli *virulence factors* enteropathogenic, enterotoxigenic, enteroaggreative
E. coli *epidemiology* intestinal tract of humans and many other animals
E. coli *infections* UTI, infantile diarrhea, hemorrhagic diarrhea, colitis, HUS, dysentry, traveler's diarrhea, persistent pediatric diarrhea, pediatric diarrhea, septicemia and menegitis
uropathogenic E. coli widely recognized as most common cause of UTIs in humans
enteradherent pathogens EPEC, EHEC, EIEC, ETEC EPEC: pathogenicity islands (infantile diarrhea); EHEC: shinga toxin/ verotoxin (hemorrhagic diarrhea, colitis, HUS); EIEC: invasion (dysentry); ETEC: LT, ST (traveler's diarrhea)
enteradherent pathogens EAEC and DAEC EAEC: AAF fimbriae Afa/Dr adhesions, AIDA-1, pathogenicity islands (persistent pediatric diarrhea); DAEC: (pediatric diarrhea, UTIs)
Klebsiella *colony morphology* variable motility, grow on Simmons citrate and in potassium cyanide broth, moist mucoid colonies
Klebsiella *gram stain results* gram-negative bacilli
Klebsiella *testing results* non produce H2S, few hydrolyze urea slowly, mthyl red-negative, Voges-Proskauer-positive, no indole is produced from tryptophan
Klebsiella *virulence factors* large polysaccharide capsule
Klebsiella *epidemiology* usually found in the GI tract of humans and animals
Klebsiella *infections* wound infections, UTIs, liver abscesses, and bacteremia
Enterobacter, Cronobacter, Pantoea *colony morphology* resembles Klebsiella on MAC agar, grow on Simmons citrate and in potassium cyanide broth, yellow pigment
Enterobacter, Cronobacter, Pantoea *gram stain results*
Enterobacter, Cronobacter, Pantoea *testing results* methyl red-negative, Voges-Proskauer-positive, usually produceornithine decarboxylase; Lysine decarboxylase
Enterobacter, Cronobacter, Pantoea *virulence factors* produce ornithine decarboxylase
Enterobacter, Cronobacter, Pantoea *epidemiology* isolated from human sources such as blood, wounds, and sputum
Enterobacter, Cronobacter, Pantoea *infections* meningitis, bacterimia
Serratia *colony morphology* red pigment when growing at room temp
Serratia *gram stain results* gram-negative rod
Serratia *testing results* positive ONPG, positive for sucrose (biogroup 1), raffinose, and ornithine, (biogroup 2) indole-positive
Serratia *virulence factors* DNase, highly resistant to antimicrobials
Serratia *epidemiology* isolated from human sources
Serratia *infections* nosocomial infections of the urinary tract, respiratory tract, bacteremia
Hafnia *colony morphology* Motility occurs at 30 degrees C. by peritrichous flagella; Colonies are non-lactose-fermenters and may resemble Salmonellae. Most strains are translucent or colorless; rare strains may produce red or pink colonies on media containing sucrose.
Hafnia *gram stain results* gram-negative rod
Hafnia *testing results* Oxidase-negative; Catalase-positive; Lysine- and ornithine-decarboxylase-positive; H 2 S (Triple Sugar Iron - TSI)-negative; Urease-negative; Indole-negative; DNase-negative; ONPG-positive; Reduces Nitrate to Nitrite
Hafnia *virulence factors* no capsules or spores
Hafnia *epidemiology* occurs in man and animals and birds, and in natural environments such as soil, sewage and water; found in clinical specimens, especially from feces, occasionally blood, sputum, urine, and wounds, abscesses, the throat, abdominal cavity and autopsies.
Hafnia *infections* H. alvei seem to be opportunistic pathogens which produce infections in patients with underlying illnesses; a possible causative agent of intestinal disorders; no conclusive evidence has been obtained regarding its enteropathogenicity
Proteus *colony morphology* produces swarming colonies on SBA
Proteus *gram stain results* gram-negative rod
Proteus *testing results some are negative for H2S, differentiated by indole and ornithine decarboxylase tests,
Proteus *virulence factors* have numerous factors including fimbriae, flagella, outer membrane proteins, lipopolysaccharide, capsule antigen, urease, immunoglobulin A proteases, hemolysins, amino acid deaminases, and, finally, the most characteristic attribute of Proteus
Proteus *epidemiology* isolated from urine, wounds, and ear and bacteremic infections
Proteus *infections* responsible for 3% of all hospital acquired infections particularly UTIs, causes lower and upper urinary tract infection,
Morganella *colony morphology* facultative anaerobes, motile
Morganella *gram stain results* Gram-negative bacillus
Morganella *testing results* oxidase negative and catalase positive. acid and gas from the metabolism of D-glucose, indole positive, VP negative, MR positive, can be grown in KCN, urease positive,
Morganella *virulence factors* enzyme, that is resistant to some urease. While, they are resistant to amoxicillin-clavulanic acid, cephalothin, gentamicin, penicillin, piperacillin, tetracycline, and trimethoprim-sulfomethaxzole.
Morganella *epidemiology* intestinal tract of humans and other mammals and reptiles
Morganella *infections* endophthalmitis, central nervous system infections, Ludwig’s angina, bacteremia, and urinary tract infection
Providecia *colony morphology* All are motile, with peritrichous flagella,
Providecia *gram stain results* gram-negative rod
Providecia *testing results* oxidatively deaminate phenylalanine hydrolyze urea
Providecia *virulence factors* invasive isolates
Providecia *epidemiology* The modes of transmission may include nosocomial sources, such as hospital food and equipment, intravenous solutions and human contact through contaminated sk in surfaces. Long-term indwelling catheters are a prime site of colonization and
Providecia *infections* UTI
Edwardsiella *colony morphology* MacConkey agar they form pale coloured colonies which can become pink on further incubation due to fermentation of lactose which can be late.
Edwardsiella *gram stain results* Gram-negative, facultatively anaerobic, rod-shaped bacteria
Edwardsiella *testing results* slow or weak fermentation of sugars by this organism. Only glucose and maltose are fermented. It is indole positive, utilise citrate, urease negative.
Edwardsiella *virulence factors* non-capsulated, motile, produce hydrogen sulphide in KI medium
Edwardsiella *epidemiology* Normal habitat is intestine of cold blooded animals and fresh water. It is mainly pathogenic to water animals
Edwardsiella *infections* causes occasional infection in humans. Its pathogenic role is uncertain but it has been isolated from wound, urine, blood and CSF
Erwinia *colony morphology* appear as white, smooth colonies; may be domed, shining, mucoid-type colonies with radial striations or appear smooth with entire edges. Craters may form around the colonies on some media. Pigments ranging from cream, pale yellow-light pink.
Erwinia *gram stain results* gram-negative rods, pairs or chains
Erwinia *testing results* Catalase-positive. PYR-positive. (Pyrrolidonyl-beta-naphthylamide). ONPG-positive (beta-galactosidase). Acid produced from carbohydrates. Oxidase-negative. Nitrates are not reduced. Moeller's-decarboxylase-negative.
Erwinia *virulence factors* Type III secretion system (T3SS), the exopolysaccharide (EPS) amylovoran, biofilm formation, and motility
Erwinia *epidemiology* major global threat to commercial apple and pear production
Erwinia *infections* plant pathogens, are not significant in human infections
Pectobacterium *colony morphology* n Logan’s medium and did not produce blue pigmented indigoidine on GYCA medium nor “fried egg” colonies on PDA.
Pectobacterium *gram stain results* non-fluorescent, gram-negative, facultative anaerobes
Pectobacterium *testing results* oxidase-negative and catalase-positive; did not produce acid from α -methyl glucoside, sorbitol and maltose, nor reducing substances from sucrose, but utilized lactose and trehalose, and did not produce indole or lecithinase.
Pectobacterium *virulence factors* type II secretion system (T2SS) , adhesions , metalloproteases , and a type III secretion system (T3SS)
Pectobacterium *epidemiology* ubiquitous in soil, wa ter, and atmospheric samples worldwide and can infect species from 24 orders of plants
Pectobacterium *infection* soft rot disease
Citrobacter *colony morphology* grow well on ordinary media producing smooth, convex, non pigmented 2-3 mm colonies
Citrobacter *gram stain results* gram negative bacilli, motile with peritrichous flagella, non-sporing, non-acid fast
Citrobacter *testing results indole= + except C.freundii, MR= +, VP = neg, Citrate positive, urease weakly positive, H2S is produced by C.freundii. Mannitol fermentation- positive. Lactose fermentation-positive variable, always produce β-galactosidase (ONPG positive).
Citrobacter *virulence factors* endotoxins, O (somatic) and H (flagellar) antigen, capsular antigen, adhesion proteins produced by bacteria.
Citrobacter *epidemiology* normal commensals of human gastrointestinal tract
Citrobacter *infections* They can cause UTI, infection of gall bladder, middle ear. C.koseri may occasionally cause neonatal meningitis.
primary intestinal pathogens from the Enterobacteriaceae Salmonella, Shigella, Yersinia
Salmonella *colony morphology* faculatively anaerobic, clear colorless, nonlactose fermenting with black centers
Salmonella *gram stain results* gram-negative bacilli
Salmonella *testing results* do not ferment lactose; indole negative; Voges-Proskauer negative; phenylalanine deaminase negative; urease negative; produce H2S (except Salmonella Paratyphi A); do not grow with potassium cyanide
Salmonella *virulence factors* fimbriae in adherance, ability to transverse intestional mucosa
Salmonella *epidemiology* found in cold-blooded animals as well as in rodents and birds
Salmonella *infections* acute gastroenteritis (food poisoning); Typhoid fever; Nontyphoidal bacterimia; carrier state following infection
Shigella *colony morphology* clear, non-lactose-fermenting
Shigella *gram stain results* Gram-negative, nonmotile, nonspore forming, rod-shaped
Shigella *testing results* nonmotile; only S. flexneri produce gas from glucose; do not hydrolyze urea; do not produce H2S; do not decarboxylate lysine;
Shigella *virulence factors* acid tolerance; effector proteins; the Mxi-Spa T3SS, toxins; motility; adherence;
Shigella *epidemiology* humans are reservoir though can be transmitted by flies, fingers, and food or contaminated water
Shigella *infections* dysentry; fever watery diarrhea; gastroenteritis;
Yersinia pestis *colony morphology* gray-white translucent on BAP and chocolate; may appear opaque and yellow in 48hrs; "fried egg" or "hammered copper" on Ba in older cultures; Clear or white on MAC at 48hrs
Yersinia pestis *gram stain results* gram-negative, short plump bacillis
Yersinia pestis *testing results* non-motile; catalase positive; oxidase negative; urease negative; indole negative; flocculent or "stalacite" growth in broth
Yersinia pestis * virulence factors* encoded with plasmids; codes for phospholipase; codes for a protease, activates plasminogen in human hosts; encode several proteins; adhesion; multiply in macrophages; produce pro-inflammatory cytokines
Yersinia pestis *epidemiology* inhalation, flea bites
Yersinia pestis *infections* plague, bubonic, gladular, septicemic, and pneumonic
Yersinia enterocolitica *colony morphology* motile at 25°C/nonmotile 36°C non-spore-forming, faculatively anaerobic
Yersinia enterocolitica *gram stain results* gram-negative coccobacillus
Yersinia enterocolitica *testing results* Glucose fermenation without gas production, urea usually positive (about 75%), H2S negative. Lactose negative (but ONPG positive), sucrose and mannnitol positive.
Yersinia enterocolitica *virulence factors* some strains can produce small amount of ga
Yersinia enterocolitica *epidemiology* zoonotic disease occurring in humans as well as a wide array of animals such as cattle, deer, pigs, and birds.
Yersinia enterocolitica *infections* usually lead to mild self-limiting enterocolitis or terminal ileitis in humans
screening stool cultures for pathogens
Created by: luceroapril