Gram Negative Rods (Exam 1) Flashcards
Where are enterobacteriaceae found
ubiquitous: soil, water, vegetation, intestinal tract of humans and animals
What are the air requirements of enterics
facultative anaerobes: can survive with or without O2
List the gram stain results for enterobacteria
Gram negative
rods
What is the oxidase result of enerobacteriaea
Negative
What is the catalase of enterics
positive
Do enterobacteriae ferment glucose
yes
What type of agar is used to grow enterics
MacConkey agar
What type of transmission is shown by enterics
human to human
animal to human
What are the common virulence factors of enterics
capsule
Flagella
Endotoxin
What are the antigens of the capsule for enterics
K antigen
Vi antigen in salmonella
What are the antigens of the flagella
H antigen
What type of secretion system do enterobacteria use
Type III
How are bacteria typed
H antigen
How are endotoxins typed
O antigen
Where is LPS contained gram negatives
outer membrane
What is MacConkey agar selective for
gram-negative rods
What is MacConkey agar differential for
lactose fermenters
How does MacConkey show when it differentiates
purple growing colonies: lactose +
beige colonies: lactose -
What is EMB agar selective for
gram-negative rods; lactose fermenters
How will EMB colony growth appear
dark colonies
How will E. coli appear on EMB
metallic green
What specific organisms grow on MacConkey
E. coli Salmonella Shigella Yersinia Klebsiella Proteus
What specific organisms are lactose +
E. coli and Klebsiella
What specific organisms are lactose -
Salmonella, shigella, Yersinia, Proteus
What organism can be used as an indicator of fecal contamination of water supplies
E. coli
What enteric is associated with traveler’s diarrhea
ETEC
What does ETEC stand for
Enterotoxin E. coli
What are the two toxins produced by ETEC
LT1
STa
What is LT1
heat labile enterotoxin
What is STa
heat stabile enterotoxin
What is the mechanism of LT1
increases cAMP
What is the mechanism of STa
increases cGMP
How ETEC transmitted
consumption of fecal contaminated food/water
What is the incubation period for ETEC
24-72 hours
What is the duration of ETEC
3-5 days
What are the symptoms of ETEC
explosive watery diarrhea
abdominal cramps
Fever +/-
nausea/vomiting
How does EIEC cause illness
invaded GI epithelium
Does EIEC use an enterotoxin
no
What is the incubation period for EIEC
10-18 hours
What is the durration of EIEC
3-5 days
What are the symptoms of EIEC
watery diarrhea
fever
abdominal cramps
bloody diarrhea
What is unique to the diarrhea of EIEC
starts watery diarrhea then turns to bloody diarrhea
What population is most effected by EPEC
Infants
those in developing countries
How are infants most susceptible during EPEC
dehydration; can be fatal
What does EPEC stand for
enteropathogenic e. coli
How does EPEC cause disease
attachment using pili, destruction of microvilli, cell death
What feature does EPEC cause with disease
lesions in the GI tract
What are the symptoms of EPEC
watery diarrhea, fever, vomiting
What population will be affected by enteroaggregative E. coli
infants and travelers
What are the symptoms of EAggEC
persisten watery diarrhea for >14 days
What is unique about the diarrhea of EAggEC
persisten for > 14 days
How does EAggEC cause disease
cells for aggregates that secrete mucus and form a biofilm
enterotoxins can increase in fluids leading to watery diarrhea
What toxins are released by EAggEC
EAST and PET toxins
What do EAST and PET toxins lead to
increased fluid secretion and watery diarrhea
What type of E. coli will produce a Shiga-like toxin
STEC
EHEC
What does EHEC stand for
enterohemorrhagic
What is the serotype of EHEC
O157:H7
The O part of a serotype is what
O antigen
The H part of a serotype is what
flagellar antigen
Where is EHEC normally found
normally in GI tract of cattle, goats, sheep
How is EHEC spread
fecal-oral (children at petting zoos)
What is the infective dose of EHEC
10-100 organisms
What type of toxin is produced by EHEC
shiga-like toxins
Where are the genes for shiga-like toxins found
phage
What is the mode of action of the toxin produced by EHEC
binds to 28SrRNA and disrupts protein synthesis
Where are the receptors for shiga toxin found
intestinal cells and kidney cells
How might EHEC affect the kidneys
toxin spread throughout the blood stream and binds to the kidney, the bacteria stay in the gut
What are the incubation period of EHEC
3-4 days
How long does EHEC last
3-7 days
What are the symptoms of EHEC
watery diarrhea progresses to gross bloody diarrhea
severe stomach cramps
low grade fever
vomiting
What is unique about the diarrhea of EHEC
starts as watery diarrhea but becomes grossly bloody
What are the two syndromes associated with EHEC
Hemorrhagic colitis
hemolytic uremic syndrome
What is hemorrhagic colitis
bloody diarrhea
How will hemolytic uremic syndrome associated with EHEC present
hemolytic anemia
renal failure
thrombocytopenia
Who is most at risk for developing HUS
children and elderly
What percent of O157:H7 cases progress to HUS
5-10%
What is the treatment for hemolytic uremic syndrome associated with EHEC
fluids, supportive care, dialysis
What antibiotics should be used in HUS
none, it will exacerbate the disease
What agar can be used to diagnoses EHEC
SMAC
What is SMAC
sorbitol MacConkey agar
95% of E. coli cultured on SMAC are what
lactose +
sorbitol +
O157:H7 cultured on SMAC are what
lactose +
sorbitol -
What are the laboratory diagnostic methods for EHEC
serotyping using O157 and H7 antiserums
direct detection of shiga-like toxin (verotoxin)
direct PCR to detect presence of SLT genes
What is the leading cause of UTI
E. coli, endogenous infection
How does E. coli cause UTIs
uses pili to ascend into bladder
What is one of the major causes of neonatal meningitis
E. coli
How does E. coli lead to septicemia
starts in GI tract or urinary tract and spreads
What are the two species of Salmonella
S. enterica
S bongori
What will be the lactose fermentation results of salmonella
Lactose neg
What is the H2S results of salmonella
H2S positive
What are the 2 common diseases caused by Salmonella enterica
Typhoid fever
Enteric infections
What strain of Salmonella enterica causes typhoid fever
S. typhi
What strain of Salmonella enterica causes tyenteric infections with diarrhea
S enteritidis
What animals/reservoir are salmonella enterica associated with
humans and warm blood animals
What animals/reservoir is salmonella bongori associated with
cold-blooded animals
How is salmonella typhi transmitted
fecal oral route
Where does ingested salmonella typhi spread inside the body
small intestine to macrophages, lymphoid tissue, liver, and gall bladder
How can the gall bladder play a role in salmonella typhi carriers
bacteria grow in gall bladder and reach instestine thorugh bile duct
How long can someone shed salmonella in their feces
1 year
What are the symptoms of typhoid fever
fever headache abdominal pain constipation anorexia malais
What is found in 25% of the typhoid fever cases
rose spots (rash) on abdomen
What symptoms are unique to typhoid fever
constipation
rose spots on abdomen
What population is predisposed to salmonella infections
Sickle cell anemia
What can salmonella cause in sickle cell patients
osteomyelitis
What is salmonellosis causes by
S. enteridis
What is S. enteridis
non-typhi serotype of salmonella
What is the transmission of salmonellosis
fecal oral
What is the incubation for salmonellosis
6-48 hours
What are the symptoms of salmonellosis
diarrhea, nausea, vomiting, fever, abdominal cramps
What does a salmonella infection rely on
ability to attach and invade columnar epithelial cells and M cells
Where does salmonella infection divide in epithelial or M cells
phagocytic vesicles
What occurs after duplicating in macrophages
it kills macrophages and spreads to nearby cells
What are the four shigella species that are human pathogens
Shigella dysenteriae
Shigella boydii
Shigella flexneri
Shigella sonnei
Which shigella spp is common in the US
shigella sonnei
Which shigella spp is most severe disease
Shigella dysenteriae
What is the reservoir for shigella
humans only, no animals
What are the lactose of Shigella
nonfermenters
What is the H2S of Shigella
negative
What is another name for shigellosis
bacillary dysentery
How is shigella transmitted
fecal oral route
What is the infection dose for shigella
low; 10 organisms
What population is most at risk for contracting shigella
children, daycare centers, schools
What is the incubation for shigella
1-4 days
What is the duration of shigella
2-3 days
What are the symptoms of shigella
watery diarrhea
abdominal cramps
fever
bloody diarrhea with mucus
What is the treatment for shigella
supportive therapy; prevent dehydration
When will antibiotics be used in shigella infections
immunocompromised individuals
what does shigella use to propel from cell to cell
actin
What are the virulence factors of shigella
invasion proteins
What are the invasion proteins of shigella
IpaA, IpaB, IpaC, IpaD
Where are invasion proteins of shigella located
large plasmid
How are shigella invasion proteins passed on
secreted by type III secretion system
What is the toxin secreted by shigella
Shiga toxin
What is the mode of action for the Shiga toxin
cleaves 28SrRNA to inhibit protein synthesis
What is the lactose result of Klebsiella
fermenter
What is the Indole of Klebsiella result
negative
Which bacterium is indole positive
e. coli
What organisms is associated with a currant jelly sputum
Klebsiella pneumoniae
How will klebsiella pneumoniae present
thick bloody sputum
What are the risk factors for getting klebsiella pneumoniae
elderly males
immunocompromised
What disease is caused by klebsiella granumoatous
granuloma inguinale
How will granuloma inguinale present
painless ulcer on genitalia
How is granuloma inguinal transmitted
sexual contact
What disease is associated with proteius
UTI
What are the two proteus strains
proteus mirabilis
proteus vulgaris
What type of organism will display swarming motility
proteus
What is the main virulence factor of proteus
urease
What does urease do
convert urea into ammonia and CO2
What does urease end up causes
increase in urine pH
What does an increase in urine pH cause
formation of kidney stone
What type of calculus is formed by proteus
staghorn calculi
