Enterobacteriaceae Characteristics Quiz
44 Questions
6 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What characteristic is NOT shared by all members of the Enterobacteriaceae family?

  • Spore-forming (correct)
  • Gram negative
  • Non-capsulated except Klebsiella
  • Facultative anaerobe

Which type of fermentation is used to identify Enterobacteriaceae on MacConkey agar?

  • Glucose fermentation
  • Lactose fermentation (correct)
  • Nitrate fermentation
  • Mannitol fermentation

Which of the following is a lactose fermenter among the Enterobacteriaceae?

  • Shigella
  • Salmonella
  • Yersinia
  • Klebsiella (correct)

What type of media is used to differentiate between lactose fermenters and non-lactose fermenters?

<p>MacConkey agar (D)</p> Signup and view all the answers

Which pathogen is NOT associated with gastrointestinal diseases caused by Enterobacteriaceae?

<p>Clostridium (B)</p> Signup and view all the answers

What does the 'E' in EHEC stand for regarding pathogenic E. coli strains?

<p>Entero (C)</p> Signup and view all the answers

Which antigenic structure is commonly associated with most motile Enterobacteriaceae?

<p>H antigen (D)</p> Signup and view all the answers

What is indicated by the presence of E. coli in water?

<p>Contamination with animals or humans (D)</p> Signup and view all the answers

What type of test is the Widal test?

<p>A quantitative agglutination test for typhoid and paratyphoid (C)</p> Signup and view all the answers

Which serotype is primarily responsible for salmonellosis?

<p>S.enteritidis (B)</p> Signup and view all the answers

What is a common characteristic of the disease caused by S.choleraesuis?

<p>Responsible for septicemia after invasion (D)</p> Signup and view all the answers

Which statement about typhoid fever is correct?

<p>The organism commonly sheds into the intestine for weeks (B)</p> Signup and view all the answers

What is the primary method of transmission for Salmonella typhi?

<p>Contaminated food and human carriers (D)</p> Signup and view all the answers

What role does the Vi antigen play in typhoid pathogenesis?

<p>Aids in immune evasion (B)</p> Signup and view all the answers

In the case of uncomplicated salmonellosis, what is generally recommended?

<p>Rehydration and supportive care (D)</p> Signup and view all the answers

Which statement about antibiotic therapy for typhoid fever is true?

<p>It is essential for effective treatment (D)</p> Signup and view all the answers

What characteristic differentiates Enterotoxigenic E.coli (ETEC) from Enteroinvasive E.coli (EIEC)?

<p>ETEC primarily causes watery diarrhea, while EIEC leads to bloody diarrhea. (D)</p> Signup and view all the answers

Which virulence factor is specifically associated with Enteropathogenic E.coli (EPEC)?

<p>Bundle-forming pili (D)</p> Signup and view all the answers

What is the primary treatment approach for E.coli infections?

<p>Fluid replacement therapy (A)</p> Signup and view all the answers

What type of toxin is produced by Enterotoxigenic E.coli (ETEC) that causes gastrointestinal symptoms?

<p>Heat-stable toxin (A)</p> Signup and view all the answers

In what way does Enteroinvasive E.coli (EIEC) resemble Shigella?

<p>Both invade the intestinal mucosa and can lead to dysentery. (C)</p> Signup and view all the answers

Which group of E.coli is primarily responsible for causing hemolytic-uremic syndrome?

<p>Enterohemorrhagic E.coli (EHEC) (D)</p> Signup and view all the answers

What is a common symptom of gastroenteritis caused by Enterotoxigenic E.coli (ETEC)?

<p>Watery diarrhea (B)</p> Signup and view all the answers

What is the optimal growth temperature range for E.coli?

<p>10 – 40°C (A)</p> Signup and view all the answers

What type of bacteria is E.coli in terms of its Gram staining characteristics?

<p>Gram-negative bacilli (A)</p> Signup and view all the answers

Which E.coli serovar is most commonly associated with Enterohemorrhagic E.coli (EHEC)?

<p>O157:H7 (B)</p> Signup and view all the answers

What is the role of fimbriae in the pathogenicity of pathogenic E.coli?

<p>They assist in the adhesion to host tissues. (A)</p> Signup and view all the answers

What is the main factor that increases the risk of urinary tract infections (UTIs) related to E.coli?

<p>Short urethra in women (D)</p> Signup and view all the answers

Which testing medium would be suitable for cultivating E.coli from a urine sample?

<p>MacConkey agar (D)</p> Signup and view all the answers

What is a major clinical significance of Enteroaggregative E.coli (EaggEC)?

<p>Results in persistent watery diarrhea in infants. (D)</p> Signup and view all the answers

What is the primary cause of shigellosis?

<p>Shigella species (C)</p> Signup and view all the answers

Which Shigella species is considered the most pathogenic?

<p>S.dysenteriae (B)</p> Signup and view all the answers

What is the main transmission route for Shigella infections?

<p>Fecal-oral route (B)</p> Signup and view all the answers

Which of the following symptoms is NOT commonly associated with shigellosis?

<p>Fatigue (C)</p> Signup and view all the answers

What is the infective dose of Shigella needed to cause infection?

<p>100-200 organisms (B)</p> Signup and view all the answers

Which diagnostic method is used for detecting a Shigella infection?

<p>Immunofluorescent test (C)</p> Signup and view all the answers

How can Shigella species contribute to antibiotic resistance?

<p>By acquiring resistant genes from other bacteria (A)</p> Signup and view all the answers

Which of the following is a common clinical finding in patients with shigellosis?

<p>Bloody stool with mucus and pus (C)</p> Signup and view all the answers

What role does Shiga toxin play in the pathogenesis of shigellosis?

<p>Inhibits protein synthesis (B)</p> Signup and view all the answers

Which measure is NOT recommended for the management of shigellosis?

<p>Surgical intervention (C)</p> Signup and view all the answers

Which organism is NOT a reservoir for Shigella?

<p>Chickens (A)</p> Signup and view all the answers

What is the incubation period for shigellosis?

<p>1-7 days (B)</p> Signup and view all the answers

What bacterial structure is primarily responsible for the movement of Salmonella through intestinal mucus?

<p>Flagella (D)</p> Signup and view all the answers

Which Salmonella species is commonly associated with gastroenteritis?

<p>S.enteritidis (C)</p> Signup and view all the answers

Flashcards

Enterobacteriaceae

A large family of gram-negative bacteria commonly found in the gut.

Characteristics of Enterobacteriaceae

These bacteria are rod-shaped, lack spores, are often motile, and can survive in the absence of oxygen.

MacConkey Agar

A specialized agar media containing bile salts to inhibit growth of most other bacteria except Enterobacteriaceae.

Lactose Fermentation

The ability to break down lactose is a key feature used to categorize Enterobacteriaceae.

Signup and view all the flashcards

Lactose Fermenters (LF)

Enterobacteriaceae that can utilize lactose as a source of energy.

Signup and view all the flashcards

Non-Lactose Fermenters (NLF)

Enterobacteriaceae that cannot utilize lactose as a source of energy.

Signup and view all the flashcards

Triple Sugar Iron (TSI) Agar

A type of agar used to differentiate Enterobacteriaceae based on their ability to ferment lactose.

Signup and view all the flashcards

Pathogenic E. coli Strains

The ability of some bacteria to produce a protein that attaches to cells and causes disease.

Signup and view all the flashcards

What is a Widal test?

A laboratory test used to detect antibodies against Salmonella typhi and paratyphi, indicating a possible typhoid infection.

Signup and view all the flashcards

What is primary immunity?

The body's initial immune response to a new infection, characterized by a slower and less robust reaction compared to subsequent exposures.

Signup and view all the flashcards

What is cell-mediated immunity (CMI)?

A type of immunity that involves specialized cells directly attacking and destroying pathogens.

Signup and view all the flashcards

What kind of immunity is strong and permanent?

The strongest and most durable type of immunity, often achieved after exposure to a pathogen or vaccination.

Signup and view all the flashcards

What is Salmonella?

A genus of bacteria known for causing food poisoning and typhoid fever.

Signup and view all the flashcards

What is typhoid fever?

A severe form of Salmonella infection characterized by fever, headache, and abdominal pain, often transmitted through contaminated food or water.

Signup and view all the flashcards

What is a carrier state for Salmonella typhi?

A common carrier state where individuals harbor and shed Salmonella typhi without experiencing symptoms, potentially spreading the infection to others.

Signup and view all the flashcards

What is Vi antigen in Salmonella typhi?

The outer capsule of Salmonella typhi that plays a role in its ability to cause infection by protecting it from the host's immune system.

Signup and view all the flashcards

What causes watery diarrhea in ETEC infections?

Enterotoxigenic Escherichia coli (ETEC) produces toxins that cause diarrhea by disrupting the balance of fluids and electrolytes in the intestines.

Signup and view all the flashcards

What are the two main toxins produced by ETEC and their mechanisms?

ETEC produces two types of toxins: heat-labile toxin (LT) and heat-stable toxin (ST). LT is similar to cholera toxin and activates adenyl cyclase, leading to increased cyclic AMP production and fluid secretion. ST activates guanylate cyclase, causing increased cyclic GMP and fluid accumulation in the intestines.

Signup and view all the flashcards

How does EIEC cause dysentery?

Enteroinvasive Escherichia coli (EIEC) invades the intestinal epithelial cells, causing inflammation and dysentery.

Signup and view all the flashcards

What are the main symptoms of EIEC infection?

EIEC causes symptoms similar to shigellosis, including fever, severe abdominal cramps, malaise, and watery diarrhea followed by bloody stools.

Signup and view all the flashcards

How does EPEC cause diarrhea?

Enteropathogenic E.coli (EPEC) attaches to the intestinal mucosa via bundle-forming pili (BFP) and disrupts the microvilli, leading to diarrhea and other symptoms.

Signup and view all the flashcards

Who is typically affected by EPEC infections?

EPEC infections are common in infants and young children, often in daycare centers, and cause symptoms like diarrhea, vomiting, and low-grade fever.

Signup and view all the flashcards

What is the key virulence factor of EHEC and its effects?

Enterohemorrhagic Escherichia coli (EHEC) produces Shiga toxin, which damages the intestinal lining, leading to bloody diarrhea and potentially hemolytic uremic syndrome (HUS).

Signup and view all the flashcards

What is hemolytic uremic syndrome (HUS) and how is it related to EHEC?

EHEC can cause hemolytic uremic syndrome (HUS), a serious complication characterized by hemolytic anemia, thrombocytopenia, and kidney failure.

Signup and view all the flashcards

What are the symptoms of EAggEC infection and who is most commonly affected?

Enteroaggregative Escherichia coli (EAggEC) causes persistent watery diarrhea with vomiting and abdominal pain, mainly affecting infants.

Signup and view all the flashcards

What are the main virulence factors of EAggEC and their roles?

EAggEC attaches to the intestinal mucosa and produces enteroaggregative heat-stable toxin (EAST), which contributes to the watery diarrhea and mucosal damage.

Signup and view all the flashcards

What is the primary treatment for E. coli gastroenteritis?

The primary treatment for E. coli gastroenteritis is fluid replacement to prevent dehydration.

Signup and view all the flashcards

When might antibiotics be used for E. coli gastroenteritis?

Antibiotics are usually not recommended for E. coli gastroenteritis but may be used in severe cases or when the infection has progressed to a systemic level, such as hemolytic uremic syndrome (HUS).

Signup and view all the flashcards

What is the clinical significance of E. coli in relation to urinary tract infections?

E. coli is a common cause of urinary tract infections (UTIs), which can lead to bladder infections (cystitis) and kidney infections (pyelonephritis).

Signup and view all the flashcards

What factors increase susceptibility to UTIs?

Factors that increase susceptibility to UTIs include instrumentation, prostatic enlargement, urinary calculi, and pregnancy.

Signup and view all the flashcards

Why are women more susceptible to UTIs?

Women are more prone to UTIs than men due to a shorter urethra and other factors like pregnancy and sexual intercourse.

Signup and view all the flashcards

Shigellosis

A bacterial infection caused by Shigella species, primarily affecting the intestines. It leads to bloody diarrhea, abdominal cramps, and fever.

Signup and view all the flashcards

Shigella

A genus of bacteria responsible for causing bacillary dysentery or shigellosis.

Signup and view all the flashcards

Pathogenesis of Shigella

The mechanism by which Shigella bacteria cause disease, involving invasion of the intestinal lining and production of toxins.

Signup and view all the flashcards

Shiga toxin

A potent toxin produced by Shigella dysenteriae, responsible for severe symptoms like bloody diarrhea and abdominal pain. It has neurotoxic, enterotoxic, and cytotoxic effects.

Signup and view all the flashcards

Transmission of Shigellosis

The spread of Shigellosis is primarily through the fecal-oral route, often through contaminated food or water.

Signup and view all the flashcards

Serogroup Classification of Shigella

The classification of Shigella species based on their O antigens, leading to the identification of four serogroups (A, B, C, and D).

Signup and view all the flashcards

Drug Resistance in Shigella

The ability of bacteria to resist the effects of antibiotics, making treatment more challenging.

Signup and view all the flashcards

Salmonellosis

A bacterial infection caused by Salmonella species, which can manifest as gastroenteritis, enteric fever, or septicemia.

Signup and view all the flashcards

Antigenic Composition of Salmonella

Diverse strains of Salmonella bacteria categorized based on their O, H, and Vi antigens.

Signup and view all the flashcards

Virulence Factors of Salmonella

The factors that contribute to the virulence of Salmonella, enhancing their ability to cause disease, including endotoxin, capsule, adhesions, enterotoxin, outer membrane proteins, and flagella.

Signup and view all the flashcards

Gastroenteritis caused by Salmonella

A common form of salmonellosis characterized by nausea, vomiting, and nonbloody diarrhea. It is often caused by Salmonella enteritidis and associated with poultry and eggs.

Signup and view all the flashcards

Septicemia caused by Salmonella

A severe form of salmonellosis where Salmonella spreads throughout the bloodstream, leading to fever, chills, and potentially organ damage.

Signup and view all the flashcards

Enteric fever

Also known as typhoid fever, is a severe form of salmonellosis where Salmonella enters the bloodstream and causes systemic symptoms like fever, headache, and abdominal discomfort.

Signup and view all the flashcards

Diagnosis of Salmonellosis

The process of diagnosing salmonellosis involves collecting appropriate samples, such as blood, stool, or bone marrow, to identify the presence of Salmonella bacteria.

Signup and view all the flashcards

Carrier state in Salmonella typhi

A significant feature of Salmonella typhi, where the bacteria can remain in the body for long periods, posing a risk for transmission.

Signup and view all the flashcards

Study Notes

Enterobacteriaceae Characteristics

  • Gram-negative, non-spore-forming rods
  • Commonly found in the large intestine as commensals; some are highly pathogenic
  • Motile (peritrichous flagella) or non-motile
  • Facultative anaerobes
  • Not fastidious
  • Non-capsulated (except Klebsiella)
  • Grow on bile-containing media (MacConkey agar)

Enterobacteriaceae Metabolism

  • Ferment glucose
  • Reduce nitrates to nitrites
  • Oxidase-negative
  • Lactose fermentation is key for isolation and identification

Enterobacteriaceae Classification

  • Two major groups:
    • Lactose fermenters (LF): E. coli, Citrobacter, Klebsiella, Enterobacter
    • Non-lactose fermenters (NLF): Salmonella, Shigella, Proteus, Yersinia
  • Selective and differential media (e.g., MacConkey agar, Triple Sugar Iron (TSI) agar) differentiate LF and NLF

Enterobacteriaceae Identification

  • MacConkey Agar:
    • LF organisms form pink colonies
    • NLF organisms form colorless colonies
  • Triple Sugar Iron (TSI) Agar: used for further characterization

Enterobacteriaceae Antigenic Structures

  • Lipopolysaccharide (endotoxin): O antigen
  • Flagella: H antigen
  • Capsule: K antigen (e.g., Vi in Salmonella)
  • Cell envelope proteins
  • Pili (various antigen types, sometimes encoded by plasmids)

Enterobacteriaceae Gastrointestinal Diseases

  • Escherichia coli
  • Salmonella
  • Shigella
  • Yersinia enterocolitica

Escherichia coli (E. coli)

  • Normal GI flora
  • Extraintestinal infections: UTI, septicemia, neonatal meningitis
  • Intestinal infections (pathotypes):
    • ETEC (enterotoxigenic)
    • EIEC (enteroinvasive)
    • EPEC (enteropathogenic)
    • EHEC (enterohemorrhagic)/STEC (Shiga toxin-producing)/VTEC (verocytotoxin-producing)
    • EAEC (enteroaggregative)
    • DAEC (diffuely adherent)
  • Diarrheagenic E. coli: 6 pathotypes associated with diarrhea

E. coli Morphology & Characteristics

  • Gram-negative rods
  • Single or pairs
  • Motile (peritrichous flagella), few strains non-motile
  • Non-spore-forming, non-acid-fast
  • Aerobic/facultative anaerobes
  • Growth range: 10-40°C, optimum at 37°C
  • Simple medium growth
  • Colonies: large, grayish, thick, white, moist, smooth, opaque
  • May contain capsule
  • MacConkey medium: bright pink colonies (lactose fermenters)
  • Numerous O, K, and H antigens

E. coli Virulence Factors

  • Surface antigens
  • Toxins
  • O antigen: endotoxic activity
  • K antigen: protects against phagocytosis
  • Fimbriae: promote virulence (important in UTIs)

Pathogenesis of Pathogenic E. coli Groups

  • ETEC: watery diarrhea, nausea, and cramps; caused by heat-labile and heat-stable enterotoxins
  • EIEC: dysentery, resembling shigellosis, caused by invasion of intestinal cells
  • EPEC: low-grade fever, diarrhea; causes destruction of intestinal microvilli
  • EHEC: bloody diarrhea, possible hemolytic-uremic syndrome (HUS), caused by Shiga toxin
  • EAEC: persistent, watery diarrhea, caused by enteroaggregative heat-stable toxin (EAST)

E. coli, Shigella and Salmonella Infections: Diagnostics and Treatment

  • Diagnostic specimens: stool, urine, blood, bone marrow (as appropriate)
  • Culture/identification, immunological tests
  • Treat with antibiotics, primarily in severe systemic infections
  • Treatment in uncomplicated cases is primarily fluid and electrolyte replacement

Shigella Bacterium

  • Non-lactose fermenters (except S. sonnei)
  • Four serogroups (based on O antigens) causing bacillary dysentery or shigellosis (bloody diarrhea with pain)
  • Shigella invades the intestine, leading to epithelial damage
  • Disease symptoms develop within 2-3 days
  • Viriulence factors: Shiga toxin (neurotoxic, enterotoxic, cytotoxic)
  • Highly contagious & infective dose is low; primarily infections amongst young children
  • Stool specimen collection/culture, immunological tests for diagnosis,
  • Antibiotic treatment for severe cases, supportive care for mild disease

Salmonella

  • Over 2,000 serotypes
  • Transmitted via the fecal-oral route
  • Presents as gastroenteritis, typhoid fever, or septicemia
  • Antigenic components: O, H, Vi antigens
  • Pathogenicity factors: endotoxin, capsule (some strains), adhesions, enterotoxin, outer membrane proteins, flagella
  • Common diseases:
    • Gastroenteritis: usually caused by S. enteritidis (often from poultry/eggs), non-bloody stools, self-limiting
    • Septicemia: S. choleraesuis often involved, high fever, little gastrointestinal involvement
    • Typhoid fever (enteric fever): S. typhi, systemic infection; bacteria multiply in cells of reticuloendothelial system, re-enters intestine; longer duration, human reservoir, diagnosed via blood/bone marrow samples
  • Diagnosis: stool samples, blood cultures
  • Treatment: primarily antibiotics; severe cases require antimicrobials

Sanitary Significance of E. coli

  • Total bacterial count, coliform index are measures for water contamination (standards for drinking water).

E. coli and Urinary Tract Infections (UTIs)

  • Leading cause of UTIs
  • Commonly associated with instrumentation (catheters), prostatic enlargement, urinary calculi, and pregnancy
  • Fecal strains often enter urethra leading to cystitis

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Description

Test your knowledge on the Enterobacteriaceae family with this quiz. Explore characteristics, fermentation types, and pathogen associations specific to this important group of bacteria. This quiz is designed for microbiology students and enthusiasts who want to deepen their understanding of lactose and non-lactose fermenters.

More Like This

Enterobacteriaceae Characteristics Quiz
34 questions

Enterobacteriaceae Characteristics Quiz

FerventSulfur9441 avatar
FerventSulfur9441
Enterobacteriaceae Overview and Classification
48 questions

Enterobacteriaceae Overview and Classification

FormidablePennywhistle avatar
FormidablePennywhistle
Bacteria Review: Enterobacteriaceae
55 questions

Bacteria Review: Enterobacteriaceae

LushChicago avatar
LushChicago
Enterobacteriaceae
6 questions

Enterobacteriaceae

Millie avatar
Millie
Use Quizgecko on...
Browser
Open
Browser
Browser