Unit 4 - Enterics Flashcards by Melanie Laird

What shape are Enterobacteriaceae

GNR
Straight Rods

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What orgs are straight rods

Enterobacteriaceae (enterics)
Non-fermentative GNR

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What orgs are curved rods

Vibrio and relatives

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What orgs are bacilli to coccobacilli, fastidious

Haemophilus

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What orgs are unusual, fastidious rods

The Ella sisters
(eg. pasteurella)

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Where are enterics found?

Everywhere
“Ubiquitous”

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Where is Enterobacteriaceae found as normal flora?

Bowel of humans and animals

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Oxidase result of Enterics family

Negative

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What sugar do all enterics ferment?

Glucose

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What do all enterics reduce?

NitrATES to nitrITES

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What plates do all enterics grow on?

Non-enriched media

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What kind of oxygen environment do enterics require?

Facultative anaerobes
(can grow with or without oxygen)

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Do enterics form spores?

No,
non-spore formers

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What enterics are OPPORTUNISTIC

“run of the mill” E. coli
Klebsiella
Enterobacter
Serratia
Proteus

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Where are opportunistic enterics found?

Normal flora of the bowel (large intestine)

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Where are opportunistic enterics capable of escaping to to cause disease

Blood
Surgical wounds
Urinary Tract

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Which enterics are strict pathogens

Salmonella
Shigella
Yersinia
Some strains of E. coli (O157:H7)

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Enterics virulence factors

Adherence
Colonizing ability
Toxins
Invasiveness

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Antigenic structure of Enterics

O Ag
H Ag
K Ag

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O antigens

Cell wall antiens
Somatic antigens
Heat stabile

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H antigens

Flagella antigens
Only in motile species
Heat labile

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K antigens

Polysaccharide capsule
Heat labile
Only in some species (ex. S. typhi)

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What medias are used to ISOLATE

TSA with SBA - Non-selective, enriched, differential
MAC - Selective & Differential
EMB - Selective & Differential

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What tube medias are used to IDENTIFY
XXXXXX FIX XXXXXX

(Biochemical)
TSI
LIA
Urea
Citrate
(Enzyme production detection)

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How do enteric colonies appear on SBA?

Large, dirty, gray Not distinct Maybe slimy SOMETIMES hemolytic

How do you assess an enteric based on hemolysis?

You don't Not critical for ID

How is MAC Selective and differential?

Selective for GNR Differential for lactose or non-lactose fermentation

how are EMB Selective and differential? XXXX CONFIRM ANS XXXX

Selective for GNR Differential for Lactose fermentation or H2S production

Is E. coli normal flora?

Yes, in bowel

How does E. coli look like on the plate

Dirty gray colony Beta Hemolytic Pink - MAC Metallic Green - EMB

What organism is characteristic based on its metallic green sheen on EMB?

E. coli

What organism is characteristic for possible B hemolysis

E. coli

What organism is a slow lactose fermenter?

E. coli

Is E. coli a lactose fermenter?

No, not always

What are key biochemical reactions for E. coli

Indole positive Methyl red positive

What diseases are caused by garden variety E. coli

Uncomplicated UTIs Septicemia Menigitis (esp. in newborns)

Is Klebsiella normal flora?

Yes, of bowel

What diseases does Klebsiella cuse

UTI Opportunistic infections Pneumonia (K. pneumoniae)

Does Klebsiella ferment lactose?

Yes, always

Key biochemical reactions of Klebsiella

Citrate positive MG neg VP pos Indole neg (except K. oxytoca) Ornithine decarboxylase neg Non-motile

SKY XXXX FINISH XXXXX

Non-motile in Klebsiellae tribe S- K- Klebsiella Y- Yersinia

Is enterobacter normal flora

Yes, bowel

What diseases does Enterobacter cause

Septicemia UTIs

Does Enterobacter ferment lactose?

Yes

Is Enterobacter motile?

Yes

How does klebsiella appear on plate

Mucoid, slimy

How does enterobacter look like on a palte

Mucoid, slimy, less than klebsiella

Biochemical reactions of Klebsiella

Ornithine positive MR negative VR positive

Is serratia normal flora?

Yes of bowel

Where is serratia commonly isolated from?

Nosocomial infections

What organism is very resistant to antibiotics?

Serratia

What are lab characteristics of serratia

Slow lactose fermenter ONPG positive (way to detect if it can ferment lactose at all) Pigmented salmon to orange color DNase positive

What organism is pigmented salmon to orange color

Serratia

What organism In the klebsiellae family is Dnase positive

Serratia

Proteeae = PPM Family

Proteus Providencia Morganella

Are PPM normal flora?

Yes, bowel

What is a specific PPM feature

Deamination of amino acids (phenylalanine and lysine)

What are the only genera of enterics that can deaminate amino acids

PPM

Do PPM ferment lactose

No, none

Do PPM ferment sucrose

Some

What diseases does proteus cause

UTI Wound infection Burns Swimmers ear

What does proteus look like on a plate

Swarming on SBA (not all)

Key reactions of Proteus sp.

Quickly urease pos Deamination of a.a. Motile H2S production

2 most common proteus species?

P. mirabilis P. vulgaris

How to differentiate between P. mirabilis and P. vulgaris

mirabilis - Indole neg vulgaris - indole pos

Providencia sp. key reactions

ALL indole positive H2S negative No swarming

What is the only species of morganella

Morganella morganii

What are the key reactions of M. morganii

Same as providencia

Escherichieae Tribe

E. coli Shigella

Klebsiellae tribe

Klebsiella Enterobacter Serratia

Citrobacteriaceae Tribe

Citrobacter (used to contain Salmonella, Citrobacter, Arizona)

Where is Citrobacter isolated from

UTIs

Citrobacter lab characteristics

H2S production Urea - positive Lysine decarboxylation - Positive Lactose fermentation - Pos

What tests are used to differentiate Citrobacter from Salmonella

urea lysine decarboxylation lactose fermentation

Where is Salmonella carried

Humans AND animals Chicken, turkeys Eggs Dairy

What does Salmonella cause

Gasteroenteritis - non-typhoid species Typhoid fever - Salmonella enterica ser. Typhi

What Salmonella sp. is carried in humans only?

S. enterica serotype Typhi

Where is Shigella carried

Only humans

What does Shigella cause

Bacillary dysentery - Invasive disease of bowel - Mucous and blood in stool

Where is shigella transmitted

Day cares Close quarters Unsanitary conditions

Where is Yersinia carried

Animals

What does yersinia cause

Gastroenteritis - Y. enterocolitica Abdominal infections of lymph nodes - Y. pseudotuberculosis Plague - Y. pestis

Salmonella enterica 6 subspecies

I, II, IIIa, IIIb, IV, VI

Most human pathogens are in what subspecies of Salmonella?

Subspecies I (S. enterica subsp. enterica)

Two species of Salmonella

S. enterica S. bongori