ENTEROBACTERIACEAE

• Enterobacteriaceae 


  Gram (-) rods

  motile with peritrichous flagella or nonmotile.

  (+) growth on peptone or meat extract media without the addition of sodium chloride.

  (+) Growth MacConkey agar

  Facultative anaerobe

  Glucose fermenter (with gas production)

  (+) Catalase

  (-) Oxidase

  • Can reduce nitrate to nitrite
• Non-lactose fermenters

  Shigella spp., Salmonella spp., Proteus mirabilis, Pseudomonas aeruginosa
• Escherichia coli


  Encapsulated and motile

  ● Facultative anaerobe

  ● Certain strains are beta-hemolytic on blood

  agar

  ● Fast lactose fermenter; (+) Beta-galactose (it

  has the ability to break down lactose into

  glucose and galactose)

  ● Non-fastidious

  ● (+) Catalase
• Natural Reservoir of E. coli

  Intestine and Vagina
• Eosin-Methylene Blue agar


  Form green metallic sheen colonies in
• Serotypes


  based on antigens. These are elements that the host community considers foreign and mount an immune response)
• O antigen


  Somatic antigen that consists of repeating units of polysaccharide
• K antigen


  Capsular antigen whose in which human infections of the respiratory tract are caused particular by capsular types 1 and 2, and for the Urinary Tract: Types 8, 9, 10, 24)
• Pathotype


  same disease; groups of organisms of the same species that causes the disease in the same way.
• EHEC/STEC

  Enterohemorrhagic E.coli


  Bloody diarrhea without pus and fever.
• ETEC

  Enterotoxigenic E. coli


  Causes traveler’s diarrhea.
• EIEC

  Enteroinvasive E.coli


  Invades the intestinal mucosa
• EPEC

  Enteropathogenic E.coli


  cause of diarrhea in infants
• EAEC

  Enteroaggregative E.coli


  acute and chronic diarrhea
• UPEC

  Uropathogenic E.coli


  Causes 50% of hospital acquired UTI and 90% of community acquired UTI
• Treatment:

  Treatment:

  ● Oral rehydration salts

  ● Antibiotics

  Third generation cephalosporins

  Fluoroquinolones

  Doxycyline

  Cotrimoxazole

  • Trimethroprim-Sulfamethoxazole

  ● DO NOT GIVE anti-motility agents

  especially for pedia gastroenteritis.
• Klebsiella pneumoniae


  Causative agent of infections usually occur in immunocompromised individuals.

  ● 3rd most common cause of UTI

  ● Grows well in MacConkey Agar

  ● Major cause of hospital acquired infections

  ● Facultative anaerobes

  ● Non motile

  ● Possesses prominent polysaccharide capsule

  ● Beta-lactamase positive

  ● Urease positive

  ● Lactose fermenter

  ● Iron uptake system

  ● Part of the normal flora of the human mouth

  and intestine
• Diabetes and Alcoholism


  causes formation of lung abscess due to aspiration of the microbe in the oropharynx
• Central Venous Catheters (CVC)


  bacteremia leading to endocarditis and meningitis.
• GET UPS you FAT ALCOHOLIC!

  GET UP: non-motile

  U: Urinary Tract Infection

  P: Pneumonia

  S: Sepsis

  FAT: Fat Capsule

  Alcohol: Alcoholic and Nosocomial patients
• Serratia marcescens


  Opportunistic microorganism

  ● Motile

  ● Facultative anaerobic

  ● Urease (+)

  ● Catalase (+)

  ● Slow lactose fermenter

  ● Prodigiosin (+) - red pigment, not all strains

  can produce this.
• Natural reservoir of Serratia marcescens

  Water and soil surfaces
• Proteus mirabilis


  Common cause of community acquired nosocomial UTIs

  ● Highly motile (swarming motility)

  ● Facultative anaerobic

  ● Swarming growth in discontinuous manner

  on agar

  ● Non-lactose fermenter

  ● H2S (hydrogen sulfide) (+) on TSI (tripe

  sugar iron) agar containing lactose, glucose,

  and sucrose + iron & a pH sensitive dye.

  ● Fishy odor (+) in agar

  ● Urease (+)

  ● Grows well on blood agar and Mac Conkey

  agar.

  ● Natural reservoir: soil, water, intestinal flora

  ● Resistant to polymyxin and tetracyclines
• Shigella spp.


  Causes acute infectious diarrhea

  ● One of the most common causes of bloody

  diarrhea

  ● Facultative anaerobe

  ● Nonmotile

  ● Non-lactose fermenter

  ● Urease and oxidase (—)

  ● H2S (—)

  ● Resistant to low pH of gastric acid

  ● Invades colonic mucosa via microfold cells

  of Peyer patches

  ● Natural reservoir: Humans only
• 4 Species of Shigella

  ● S. dysenteriae

  ● S. flexneri

  ● S. boydii

  ● S. sonnei
• Shigellosis


  Related to dysentery

  • Sudden onset:

  ● Abdominal and rectal cramping

  ● Watery mucous flaked diarrhea

  (may contain blood/pus)

  ● Pain

  ● Fever

  ● Loss of appetite

  ● Fecal incontinence
• Salmonella spp.


  Encapsulated

  ● Facultative intracellular

  ● Facultative anaerobe

  ● Glucose fermenter

  ● Non-Lactose fermenter

  ● Oxidase (–)

  ● H2S (+)

  ● Non-spore forming

  ● Flagella (+)

  ● Type III secretion system (+)
• Salmonellosis


  Gastrointestinal tract dysfunction leads to water and electrolyte efflux into the intestinal lumen leading to diarrhea.
• Typhoid fever


  Appear 1-2 weeks after initial infection ● Takes 4-6 weeks to resolve

  ● High, sustained fever

  ● Abdominal pain

  ● Constipation followed by diarrhea

  ● Rose/Salmon colored spots on

  chest/abdomen

  ● Hepatomegaly and splenomegaly as

  infection spreads
• Pseudomonas aeruginosa

  ● Gram(–)rods

  ● Capsulated

  ● Obligate aerobe

  ● Non-Lactose Fermenter

  ● Non-Spore Forming

  ● Catalase (+) Citrate (+) Oxidase (+)

  ● Pili (+)

  ● Flagellum (+)

  ● Forms greenish-blue colonies

  ● Fruity, Grape-like odor or corn taco-like odor (+)

  ● Opportunistic pathogen

  ● Multidrug resistant