Micro 107 Unit 6 Flashcards
Which is the only Enteric bacteria whcih is oxidase positive?
Plesiomonas spp.
What are the selective and differential media for Enterobacteriacae(Enterics)?
MAC, EMB, HE(K), XLD.
What is MAC differential for?
Lactose fermentation
What is EMB differential for?
Lactose and Sucrose fermentation
What is HE(K) differential for?
Lactose and Sucrose fermentation. Bile salts inhibit gram-positive and some gram-negative
What color do Shigella colonies apear as on AXD agar?
Colorless or red
What are the two major types of pathogens?
Opportunistic: Normal Flora
Primary: Ingesting contaminated food or water
What are the key 3 primary Enteric pathogens?
Salmonella, Shigella, and Yersinia
What are the general characteristics of Escherichia coli (E. coli)
Dry pink colony with a halo on MAC
Green metallic sheen on EMB
What are the key tests described in the IMViC accryonym
Indole
Methyl red
Voges-Proskauer
Citrate
What is the IMViC for E. coli
++–
What carbs does E. coli ferment
Glucose, Lactose, Trehalose, and Xylose
GTXL
Why is Uropathogenic E. coli clinically significant
Most common cause of UTI’s in humans
What are the 5 major categories of E. coli
ETEC
EPEC
EIEC
EHEC
Enteroadherent
- DAEC
- EAEC
What climate is ETEC generally acquired in giving it the name “travelers diarrhea”
tropical and subtropical climates
Where do EPEC outbreaks occur
Nurseries and daycares
What conditions can EHEC O157:H7 lead to
Hemorrhagic diarrhea
Colitis
Watery diarrhea progressing to bloody diarrhea in young children and elderly
HUS
What are the diagnostic tests for E. coli O157:H7
Primary screening on a stool culture
MAC agar with sorbitol (SMAC)
What seperates E. coli 157:H7 from most other E. coli
Does not ferment sorbitol in 48 hours
Klebsiella, Enterobacter, Serratia, Pantonea, Cronobacter, and Hafnia are associated with what kind of infections
opporunistic and nosocomial
Klebsiella pnumoniae is the most common isolate of the Klebsiella family and appears ______ on a BAP
moist, gray, mucoid colonies
What are the 4 clinically significant species of Enterobacter
E. cloacae
E. aerogenes
E. geroviae
E. hormaechei
Which 2 Enterobacter species are the most commonly isolated
E. CLoacae
E. aerogenes
Proteus Species are what kind of bacteria
normal intestinal microbiota (Normal Flora)
What is the colony morphology of Proteus spp.
Swarming colonies and a distinct “burnt chocolate” smell
The Morganella spp.’s only species, M. morganii is isolated in ___ infections and is a cause of ___
UTI
Neonatal Sepsis
P. stuartii is implicated in nosoomial outbreaks in what unit of the hospital
Burn unit
P. stuartii is isolated in ___ cultres
Urine
What makes Providencia spp. difficult to treat
High resistance to antimicrobials
Edwardsiella does not grow on what medium
Simmon’s citrate
Of the 11 Citrobacter spp. what are the 3 most common isolated
C. freundii
C. koseri
C. braakii
What infection is C. freundii associated with
UTI
What infection is C. koseri associated with
Neonatal Meningitis
What is the colony morphology of Salmonella spp.
Clear, colorless, non-lactose fermenting colonies with black centers on MAC agar
What tests do we run to dfferentiate Salmonella subgroups
Lysine decarboxylase rules out S. paratyphi
Ornithone decarboxylase rules out S. typhi
Trehalose fermentation rules out S. cholaraesuis
What is the primary virulence factor of S. enterica
Enterotoxin: involved in gastroenteritis
Clinical infections of S. enterica present as ____ and are caused by ___
Food poisoning with vomiting and diarrhea
Ingestion of organism in contaminated food
When do symptoms of S. enterica appear
8-36 hours after ingestion of contaminated food
Most cases of Salmonella gastroenteritis (Salmonellosis) are ____
Self Limiting
Development of Typhoid fever, caused by S. typhi can lead to
Fever, malaise, anorexia, lethargy, myalgia, and a dull headache
Define Carrier State
Individuals who recover from infection but harbor the organisms in the gallbladder
All Shigella spp. can cause ___
Dysentery
The only resivoir of Shigella spp. is ___
Humans
Local inflammation and shedding of intestinal lining containing mucus, blood, ulcer formation, and tenesmes (rectal prolapse)
Dysentery
Biochemical identificaton of SHigella spp.
No urease production
No H2S in TSI
Nonmotile
Which Yersinia spp. is considered a class A bioterrorism agent
Y. pestis
Y. pestis causes _____
Plague in the Bubonic, Septicemic, and Pneumonic forms
When does the septicemic form of the plague occur
when the bacteria migrate to the bloodstream
What specialized agar is used for the identification of Y. enterocolitica
CIN agar
What cultures is Kluyvera isolated from
Respiratory, Urine, and Blood
What transport media must labs provide for Enterobacteriaceae
Cairy-blair
Amies
Stuart
What should all fecal specimens be screened for
Salmonella
Shigella
Campylobacter
What selective media should be used for stool specimens
HE(K)
XLD
EMB
What environment is Vibrio commonly found in
Aquatic environments including fresh and salt water
An increase in the isolation of Vibrio can be linked to
Increased consumption of seafood
Undercooked or raw seafood
V. cholera is the causative agent of ____
cholera
Where does V. cholera originate
The Bengal region of India and Bangledesh
What are the clinical manifestations of cholera
Severe acute gastroenteritis
Rice-water stool ( stool with fleks of mucus)
What is the recomended treatment of cholera
IV and oral fluids containing electrolytes
What is the second most common Vibrio spp.
Vibrio parahaemolyticus
V. parahaemolyticus was discovered in ___
Japan in 1950
Known as summer diarrhea
As of 2007 the CDC requires that cases of _____ be reported to local and state public health agencies
V. vulnificus
If clinical history indicates Vibrios use
thiosulfate, citrate, bile salts, sucrose
(TCBS agar)
Biochemical identification of Vibrios spp.
Catalase positive
Oxidase positive
Ferments glucose
Reduces nitrate to nitrite
Susceptible to Vibriostat disc
Biochemical identification of Aeromonas
Oxidase positibe
Indole positive
Where is Plesimonas found
Soil and aquatic environments
What are the 3 major clinical types of gastroenteritis
Watery diarrhea
Subacute or chronic disease( 2 weeks to 3 months)
Dysenenteric form resemblig cholitis
Who is most at risk of Plesimonas
Vets and zookeepers
What agar can be used to enhance the isolation of Plesimonads
IBB
Biochemical Identification of Plesimonas
Oxidase Positive
What is unique to Campylobacter spp.
They are Microaerophillic organisms
- They require oxygen but at a concentration of only 5%
The transmisson of Campylobacterioses has ben attributed to
Infected pets such as dogs cats and birds
What is the most common cause of bacterial gastroenteritis
Campylobacter jejuni
What symptoms follow infection of Campylobacer jejuni
Cramps, bloody diarrhea, fever, chills, and rarely nausea and vomiting
Helicobacter pylori is repsonsible for
Damaging tissue, resulting in gastric, peptic, and duodenal ulcers
What transport medium must be used for Campylobacter
Cary-Blair for stool samples
What environment must Campylobacter plates be incubated in
Microaerophillic, and Capnophilic
5%-10% oxygen and 10% CO2 at 42*C
What is the microscopic morphology of Campylobacter
Non-spore forming gram negative rods
S or segull-wing shape
biochemical identification of Campylobacter
Oxidase positive
Exhibits a “darting” motility on hanging drop preperations
For the laboratory identification of Helicobacter, gastric biopsy can be tested for the presens of a ___
Rapid Urease reaction
Rapid Urease reaction test
Requires christensen’s urea
Rapid color change in 2 hours
Another commercial rapid test for Helicobacter
Urea breath test
Miscellaneous Gram negative bacilli
Do not ferment carbohydrates
grow only in aerobic environments
prefer moist environments
Clinical infections of non-fermenters
Account for 15% of all gram-negative bacilli isolated in clinial infections (Pseudomonas aeruginosa 5-15%)
Pseudomonas aeruginosa accounts for ____ of all nosocomial infections, especially pneumonia and bacteremia
5-15%
Pseudomonas aeruginosa can cause
pulmonary disease, especially among individuals with cystic fibrosis
What is the primary virulence factor of Pseudomonas aeruginosa
Alginate
-A polysaccharide polymer
Overproduction of the Alginate factor in Pseudomonas aeruginosa produces
Mucoid colonies. Seen primarily in cystic fibrosis patients
Laboratory identification of Pseudomonas aeruginosa
Many strains produce a fruity grape like odor caused by the presence of 2-aminoacetophenone
Biochemical identification of Pseudomonas aeruginosa
Motile
Indole negative
ADH positive
Growth at 42*C
Antimicrobial susceptibility for Pseudomonas aeruginosa
Carbapenems
Flouroquinolones
Clinical infections for P. stutzeri
Endocarditis
Septic arthritis
Conjunctivitis
Culture and colony morphology for P, stutzeri
Wrinkled, leathery, adherent colonies that may produce a light yellow or brown pigment
P. mendocina is considered
A contaminant
Acinetobacter spp. appears as
gram negative coccobacilli
