opportunistic enterobact

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Fe A. Bartolome, MD, FPASMAP Department of Microbiology Our Lady of Fatima University

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Page 1: Opportunistic Enterobact

Fe A. Bartolome, MD, FPASMAP Department of Microbiology

Our Lady of Fatima University

Page 2: Opportunistic Enterobact

• commensals of the large intestines

• infections found outside the intestines

• can infect any tissue of the body

• usual type of infection produced:

1.UTI 4. Meningitis

2.Wound infection 5. Septicemia

3.Pneumonia 6. GI disorders

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Klebsiella-Enterobacter-Serratia Group

• Lactose fermenters EXCEPT Serratia group

• Give (+) Voges-Proskauer reactions presence of acetylmethyl carbinol

• Resistant to Ampicillin

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Klebsiella

Characteristics:

1. Non-motile

2. Encapsulated – large polysaccharide capsule

3. Weak urease producer

4. Mucoid appearance of isolated colonies due to capsule

5. IMViC: - - + + TSI: A/A + gas

6. (+) test for lysine decarboxylase & citrate

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Klebsiella

Klebsiella pneumoniae

• Friedlander’s bacillus

• Most commonly isolated member

• Present in respiratory tract & feces of about 5% of normal individuals

• Cause nosocomial or community-acquired infections

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Klebsiella

Klebsiella pneumoniae

• Clinical:

Primary lobar pneumonia

Individuals with underlying medical problems

At risk: alcoholics & people with compromised pulmonary function

Extensive hemorrhagic necrotizing consolidation of lungs (+) blood-tinged, thick, non-putrid sputum

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Klebsiella

Klebsiella pneumoniae

• Clinical:

Others: UTI, wound infection, bacteremia, meningitis, endophthalmitis

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Klebsiella pneumoniae endophthalmitis

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Klebsiella pneumoniae wound infection

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Klebsiella

Klebsiella oxytoca

• Biochemically similar to K. pneumoniae but indole (+)

• Similar infection to K. pneumoniae

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Klebsiella

Klebsiella ozaenae

• Fetid, progressive atrophy of mucous membranes of the nose chronic atrophic rhinitis

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Klebsiella

Klebsiella rhinoscleromatis

• Rhinoscleroma – chronic granulomatous destruction of nose and pharynx

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Enterobacter

• Also known as Aerobacter

• Usually nosocomially acquired

• Characteristics:

1.Motile

2.Usually non-encapsulated

3. (-) urease production

4.Citrate and ornithine decarboxylase (+)

5. IMViC: - - + + TSI: A/A + gas

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Enterobacter

Enterobacter cloacae

• Cause majority of infections

• Most frequently associated with UTI

Enterobacter aerogenes

• With small capsules

• May be found free-living as well as in the intestinal tract

• Cause UTI and sepsis

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Serratia

Characteristics:

1.Able to produce DNase, lipase and gelatinase

2.Resistant to Colistin and Cephalotin

3.Usually non-pigmented

4.Ferments lactose slowly

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Serratia

Serratia marcescens

• Most frequently isolated

• Common opportunistic pathogen

• (+) production of bright red pigment (prodigiosin)

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Serratia

Serratia marcescens

• Infections associated with:

1. Invasive procedures – IV catheterization, resp. intubation & urinary tract manipulation

2.Contamination of water in respiratory therapy devices

3.Narcotics addicts

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Serratia

Serratia marcescens

• Diseases:

1.Pneumonia

2.Bacteremia

3.Endocarditis

4.Wound infection

5.Septicemia

6.Outbreaks of UTI

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PROTEUS-MORGANELLA-PROVIDENCIA

PROTEAE

• Characteristics:

1. Deaminate phenylalanine produce phenylalanine deaminase

2. Motile

3. Grow on potassium cyanide medium (KCN)

4. Ferment xylose non-lactose fermenter

5. Urease (+)

6. Primarily cause UTI, both nosocomial and community-acquired

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PROTEUS

• Active motility via peritrichous flagella (+) “swarming” on solid media (+) expanding rings (waves) of organisms over the surface of the agar

• Cell wall O antigens (OX-2, OX-19 & OX-K) of certain strains (P. vulgaris) cross react with several species of Rickettsiae (+) Weil-Felix test

• Present in human colon, soil and water

• Virulence factors:

1. Rapid motility at 370C

2. Urease production

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Swarming gives rise to a very thin film of bacteria on the agar surface, but swarming periods are interspersed with periods when the cells stop and undergo a cycle of growth and division so that the colony has a distinct zonation, clearly seen in Fig. A. Ability to degrade urea to ammonia, by production of the enzyme urease (Figure B)

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PROTEUS

Proteus mirabilis

• Causes most community-acquired & nosocomial infections

• 2nd leading cause of community-acquired UTI

• Inhibited by penicillins

• Indole (-)

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PROTEUS

Proteus vulgaris

• Cause mainly nosocomial infection

• Indole (+)

• More resistant to antibiotics

• Treatment of choice: cephalosporin

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Proteus

• Both Proteus vulgaris & Proteus mirabilis (+) H2S production blacken butt of TSI agar

• Diseases other than UTI: pneumonia, wound infection and septicemia

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Morganella morganii

• Formerly Proteus morganii

• Urease (+)

• Cause nosocomial UTI

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Morganella morganii panophthalmitis. The conjunctiva was haemorrhagic and necrotic with mucopurulent greenish pus discharge. The cornea was oedematous and opacified.

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Providencia rettgeri

• Formerly Proteus rettgeri

• Member of normal intestinal flora

• Causes UTI

• Often resistant to antimicrobial therapy

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CITROBACTER

• Formerly Bethesda-Ballerup group

• Citrate (+)

• Do not decarboxylate lysine

• Slowly ferment lactose

• Occur in environment and in human colon but majority of isolates from the urinary tract

• Can cause UTI and sepsis in immunocompromised patients

• Citrobacter diversus – most frequent isolate; also an important cause of neonatal meningitis and brain abscess

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Diseases caused by members of the Enterobacteriaceae

Major pathogen Representative diseases Minor related genera

Escherichia UTI, traveler’s diarrhea, diarrhea, neonatal meningitis

Shigella Dysentery

Salmonella Typhoid fever, enterocolitis Arizona, Citrobacter, Edwardsiella

Klebsiella Pneumonia, UTI

Enterobacter Pneumonia, UTI

Serratia Pneumonia, UTI

Proteus UTI Providencia, Morganella

Yersinia Plague, enterocolitis, mesenteric adenitis

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Gram-negative rods causing UTI or sepsis

Species Lactose fermented

Features of the organism

Escherichia coli + Greenish metallic sheen on EMB

Enterobacter cloacae + Usually nosocomial infections & often drug resistant

Klebsiella pneumoniae

+ Large mucoid capsule and viscous colonies

Serratia marcescens - Red pigment produced; nosocomial infections; drug resistant

Proteus mirabilis - Swarming phenomenon; produce urease

Pseudomonas aeruginosa

- Blue-green pigment; fruity odor; nosocomial; drug resistant

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Lactose fermentation by members of the Enterobacteriaceae & related organisms

Lactose fermented rapidly

Lactose fermented slowly

Lactose not fermented

E. coli: motile; flat, nonviscous colonies

Edwardsiella, serratia, citrobacter, arizona, providencia, erwinia, vibrios

Shigella sp.: non-motile; no gas from dextrose

Enterobacter aerogenes: raised colonies; often motile; more viscous growth

Salmonella sp.: motile, acid & usually gas from dextrose

Klebsiella pneumoniae: very viscous, mucoid growth; non-motile

Proteus sp.: swarming on agar; urea rapidly hydrolyzed

Pseudomonas sp.: soluble pigments; sweetish smell

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Triple sugar iron (TSI) agar reactions

Reactions RepresentativeGeneraSlant Butt Gas H2S

Acid Acid + - Escherichia, Enterobacter, Klebsiella

Alkaline Acid - - Shigella, Serratia

Alkaline Acid + + Salmonella, Proteus

Alkaline Alkaline - - Pseudomonas