Enterobacteriaceae Flashcards
- What are the lactose fermenters Enterobacteriaceae? What colony they will give?
- E. Coli
- Klebsiella pneumonia
- Enterobacter
- Citrobacter
- Serratia
Are they gram positive or negative bacteria?
Gram negative
Are they spore forming bacteria?
Non spore forming
Aerobic, anaerobic or facultative anaerobes?
Aerobic or facultative anaerobes
Catalase and oxidase test results?
Catalase positive, oxidase negative
Motile or nonmotile?
Some of them are motile, others are non motile
What are the non-lactose fermenters Enterobacteriaceae?
- Pertussis
- Providencia
- Salmonella
- Shigella
- Morganella
What do we call them?
Enteric bacteria
What are their antigenic structures?
Capsule, flagella, pili, O antigen and LPS
What are the antigens of the capsule and the flagella?
K antigen for the capsule, H antigen for the flagella
Which Ag induces the production of IgM?
O antigen
What are their virulence factors?
Enterotoxin, capsule, antigenic phase variation, exotoxin production, expression of adhesion factors, intracellular survival and multiplication, sequestration of growth factors, resistance to serum killing and antimicrobial resistance.
What is the antigenic phase variation?
Change of antigenicity depending on phase meaning environmental factors
What is the importance of expression of adhesion factors?
Important for colonization, so for the establishment of the disease
What is the importance of the intracellular survival and multiplication?
In order to spread
What do we mean by sequestration of growth factors?
Growth factors that bacteria cannot produce but need for their growth
What is the resistance to serum killing?
Resistance to killing by common antibodies in the serum with bactericidal properties
What is the biggest problem with Enterobacteriaceae?
Their anti-microbial resistance that spreads very quickly
What are bacteriocins?
Substances produced by bacteria to compete with pathogenic ones
Which one will produce colocins?
E. Coli
Which one will produce marcescens and what’s its color?
Serratia marcescens
Red
Which one will produce pyocins and what’s its color?
Pseudomonas
Can be black, red, blue or green
When do they cause opportunistic diseases?
When they acquire virulence factors and depending on the immune system status of the individual
Which Enterobacteriaceae are pathogenic and are not part of our normal flora?
Salmonella and Shigella
Which structure controls the production of bacteriocins?
plasmids
Which one will infect the central nervous system?
E coli
Which bacteria will infect the lower respiratory tract?
Mostly E coli and enterobacter (which are normally not part of the NF of the respiratory tract)
Klebsiella (part of the normal flora of the upper respiratory tract)
Which one will infect the bloodstream?
Any type can cause bacteremia and thus a septic shock
Which one infect gastrointestinal tract?
Salmonella, shigella, yersinia psedotuberculosis and E. coli
Which one will infect the urinary tract?
E. coli, klebsiella, Proteus, Providencia
How can we differentiate between Proteus and Providencia which have similar aspects?
Providencia is uriase negative
What’s Gastroenteritis?
A syndrome characterized by gastrointestinal symptoms including nausea, vomiting, diarrhea and abdominal discomfort
What’s diarrhea?
Abnormal fecal discharge characterized by frequent and/or fluid stool, usually resulting from disease of the small intestine and involving increase in fluid and electrolyte loss
What’s the definition desentery?
Inflammation disorder of the G.I. tract often associated with blood and pus in feces accompanied by symptoms of pain, fever, abdominal cramps, usually resulting from diseases of the large intestine
Define the enterocolitis.
Inflammation involving the mucosa of the small and large intestine
How Enterobacteriaceae are transmitted?
Fecal oral route: we can be infected boy feces from humans or animals containing pathogenic microbes or the toxins, through food, fluid or fingers.
In which medium they are cultured?
McConky medium: it inhibits the growth of gram-positive bacteria
What are the three classes of E. coli?
- Commensals
- ExPEC
- IPEC
Are the commensals part of our normal flora? Pathogenic?
Yes they are
Not pathogenic
When do they cause a disease?
Suppression of the remaining NF by antibiotics or when the peritoneum is ruptured
What are the ExPEC?
Extra intestinal pathogenic E. coli
Are they pathogenic and do they have the ability to invade other places?
They are pathogenic since they have virulence traits and cause diseases outside the intestinal tract, meaning they have the ability to invade other places, but in their normal place they do not cause diseases
What are clinical presentations of ExPEC?
UTI
Pneumonia
Neonatal meningitis
Septic shock
How do they cause urinary tract infections?
They adhere by strain specific pili to urethra causing urethritis. May ascend to the bladder causing cystitis, and in kidneys cause pyelonephritis.
How do they cause septic shock?
By endotoxin release
Why urinary tract infections are more frequent in females?
Because the urinary tract and the rectum are very close
What are the symptoms of urinary tract infections?
Frequent urination, dysuria, abdominal cramps, large amounts of bacteria and leukocyte in midstream urine.
It can be complicated by hematuria and proteinuria
What are the IPEC?
Intestinal pathogenic E. coli
Are they members of the normal flora?
No, they are pathogenic, from outside, and can cause diseases in small and large intestines
What are the clinical presentations of an infection with IPEC?
Watery diarrhea or dysentery, depending on the strain
What are the types of IPEC?
EPEC ETEC EHEC EIEC EAEC
What are the EPEC?
Enteropathogenic E. coli
What is the target age group of EPEC?
Babies and young children in developing countries where there is poor hygiene or daycare centers
How they are transmitted?
Strictly human-human transmission
What is the incubation period?
1 to 2 days
Do they have virulence factors
No they don’t
How do they cause pathology? What is their effect?
They adhere to small intestinal mucosa but do not invade, inducing structural changes in the mucosal cells.
Their effect is effacement (flattening of the microvilli)
Do they induce an inflammatory reaction?
No