Unit 4 - Enterics Flashcards
What shape are Enterobacteriaceae
GNR
Straight Rods
What orgs are straight rods
Enterobacteriaceae (enterics)
Non-fermentative GNR
What orgs are curved rods
Vibrio and relatives
What orgs are bacilli to coccobacilli, fastidious
Haemophilus
What orgs are unusual, fastidious rods
The Ella sisters
(eg. pasteurella)
Where are enterics found?
Everywhere
“Ubiquitous”
Where is Enterobacteriaceae found as normal flora?
Bowel of humans and animals
Oxidase result of Enterics family
Negative
What sugar do all enterics ferment?
Glucose
What do all enterics reduce?
NitrATES to nitrITES
What plates do all enterics grow on?
Non-enriched media
What kind of oxygen environment do enterics require?
Facultative anaerobes
(can grow with or without oxygen)
Do enterics form spores?
No,
non-spore formers
What enterics are OPPORTUNISTIC
“run of the mill” E. coli
Klebsiella
Enterobacter
Serratia
Proteus
Where are opportunistic enterics found?
Normal flora of the bowel (large intestine)
Where are opportunistic enterics capable of escaping to to cause disease
Blood
Surgical wounds
Urinary Tract
Which enterics are strict pathogens
Salmonella
Shigella
Yersinia
Some strains of E. coli (O157:H7)
Enterics virulence factors
Adherence
Colonizing ability
Toxins
Invasiveness
Antigenic structure of Enterics
O Ag
H Ag
K Ag
O antigens
Cell wall antiens
Somatic antigens
Heat stabile
H antigens
Flagella antigens
Only in motile species
Heat labile
K antigens
Polysaccharide capsule
Heat labile
Only in some species (ex. S. typhi)
What medias are used to ISOLATE
TSA with SBA - Non-selective, enriched, differential
MAC - Selective & Differential
EMB - Selective & Differential
What tube medias are used to IDENTIFY
XXXXXX FIX XXXXXX
(Biochemical)
TSI
LIA
Urea
Citrate
(Enzyme production detection)
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