Gram-Negative Bacteria Overview
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Questions and Answers

What type of infections are primarily caused by Legionella?

  • Gastrointestinal infections
  • Urinary tract infections
  • Skin infections
  • Respiratory tract infections (correct)

Which disease is caused by members of the genus Brucella in humans?

  • Rabbit fever
  • Legionnaires' disease
  • Undulant fever (correct)
  • Whooping cough

Pseudomonas aeruginosa is primarily known as which type of pathogen?

  • Opportunistic pathogen (correct)
  • Primary pathogen
  • Commensal pathogen
  • Zoonotic pathogen

What is tularemia, and what primarily causes it?

<p>A zoonosis caused by Francisella tularensis (A)</p> Signup and view all the answers

What characteristic is true for Bacteroides?

<p>Anaerobic Gram-negative rods associated with peritonitis (C)</p> Signup and view all the answers

What is the most clinically significant species of the genus Yersinia?

<p>Y.pestis (C)</p> Signup and view all the answers

What disease is primarily caused by Yersinia pestis?

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

Which organism is known for causing acute gastritis and ulcers?

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

What common infection is H.influenzae primarily known for causing in infants?

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

Which of the following species is associated with whooping cough?

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

What type of plague presents with more severe symptoms during epidemics?

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

What is a common symptom associated with cholera?

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

What is the mechanism of motility for Helicobacter species?

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

Which organism is primarily associated with infections outside the gastrointestinal tract?

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

Which of the following has the capability to cause both gastrointestinal and extraintestinal diseases?

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

What is the significance of fimbriae in Escherichia coli?

<p>They are important for adherence to mucosal surfaces. (D)</p> Signup and view all the answers

Which of the following is a pathogenic species of the genus Neisseria?

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

Which group of organisms are known to be important nosocomial pathogens?

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

What is the primary mode of transmission for Neisseria gonorrhoeae?

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

Which of the following statements is true regarding Neisseria gonorrhoeae?

<p>It is a gram-negative diplococcus. (C)</p> Signup and view all the answers

Which of these genera mainly causes diseases in the gastrointestinal tract?

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

What characteristic do all the organisms in the gastrointestinal Gram-negative rods group share?

<p>They are true facultative anaerobes. (C)</p> Signup and view all the answers

Which one of these organisms is included in the category of gram-negative rods?

<p>Campylobacter (C), Bacteroides (D)</p> Signup and view all the answers

Which of the following is NOT a pathogen mentioned in the document?

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

Neisseria species are primarily classified as which type of bacteria?

<p>Gram-negative cocci (D)</p> Signup and view all the answers

Fecal contamination is frequently important in the transmission of which type of microorganisms?

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

What is a common clinical observation associated with Neisseria gonorrhoeae?

<p>Presence in neutrophils (D)</p> Signup and view all the answers

Which species is frequently confused with Neisseria gonorrhoeae under the microscope?

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

Which of the following infections does Neisseria meningitidis commonly cause?

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

What is the most important virulence factor of N.meningitidis?

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

Which of the following vaccines is a conjugate meningococcal vaccine approved for use in adolescents and adults?

<p>MCV4 vaccine (B)</p> Signup and view all the answers

What are common symptoms that develop in individuals with meningococcal infections?

<p>Severe headache and vomiting (B)</p> Signup and view all the answers

How quickly can meningococcal septicemia develop in a previously healthy individual?

<p>In less than 12 hours (A)</p> Signup and view all the answers

What is the initial site of colonization for N.meningitidis?

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

Which serogroups are included in the MCV4 vaccine?

<p>A, C, W-135, Y (A)</p> Signup and view all the answers

What can happen within several hours of showing initial meningitis symptoms?

<p>Onset of coma (B)</p> Signup and view all the answers

What commonly accompanies joint symptoms in meningococcal infections?

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

What type of E.coli is primarily associated with traveler's diarrhea?

<p>Enterotoxigenic E.coli (ETEC) (A)</p> Signup and view all the answers

Which strain of E.coli is most commonly associated with severe symptoms, such as hemorrhagic colitis?

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

What is the primary transmission route for intestinal diseases caused by E.coli?

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

Which type of E.coli is particularly dangerous due to its potential to cause hemolytic uremic syndrome (HUS)?

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

What differentiates enteroinvasive E.coli (EIEC) from enterotoxigenic (ETEC) and enteropathogenic (EPEC) E.coli?

<p>It causes a dysentery-like syndrome. (C)</p> Signup and view all the answers

In what situation does E.coli become pathogenic in the case of extraintestinal disease?

<p>When it originates from the patient’s own flora. (B)</p> Signup and view all the answers

Which group is at a higher risk for urinary tract infections (UTIs) caused by E.coli?

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

What type of E.coli is recognized for causing persistent diarrhea in young children?

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

Flashcards

What are Gram-negative bacteria?

Gram-negative bacteria are a group of bacteria that have a unique cell wall structure. They are characterized by their ability to retain the counterstain (usually safranin) during the Gram stain, resulting in a pink or red color under the microscope.

What is Neisseria?

Neisseria is a genus of bacteria that includes two pathogenic species responsible for common infectious diseases.

What is N. gonorrhoeae?

N. gonorrhoeae is commonly known as the gonococcus and is the cause of gonorrhea.

What is N. meningitidis?

N. meningitidis is commonly known as the meningococcus and is a common cause of meningitis.

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What are the characteristics of N. gonorrhoeae and N. meningitidis?

Both N. gonorrhoeae and N. meningitidis are gram-negative diplococci, meaning they are spherical-shaped bacteria that appear in pairs. They are nonmotile, meaning they cannot move on their own.

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What is gonorrhea?

Gonorrhea is a sexually transmitted infection (STI) caused by N. gonorrhoeae.

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How is gonorrhea transmitted?

Gonorrhea is usually transmitted through sexual contact, but can also be passed to a baby during birth.

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Where is N. gonorrhoeae found in infected individuals?

N. gonorrhoeae is often found inside white blood cells called polymorphonuclear leukocytes in samples taken from infected individuals.

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Meningococcal Disease

A type of infection caused by the bacteria Neisseria meningitidis. It can develop rapidly, leading to severe illness, including meningitis and septicemia. It often affects young, previously healthy individuals.

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Enterobacteriaceae

A group of bacteria that are primarily found in the gastrointestinal tract of humans and other animals. They are facultative anaerobes and contain lipopolysaccharide (endotoxin), contributing to their pathogenic potential.

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Meningococcal Polysaccharide Capsule

A capsule surrounding Neisseria meningitidis bacteria. It prevents the bacteria from being engulfed and destroyed by immune cells (phagocytes).

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Escherichia

A genus of bacteria that includes both pathogenic and non-pathogenic species. Some strains are associated with urinary tract infections, while others are a common part of the gut microbiome.

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Salmonella

A genus of bacteria known for causing a variety of diseases, primarily gastrointestinal infections like typhoid fever and food poisoning.

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Meningococcal Pharyngitis

The initial stage of meningococcal infection, often without noticeable symptoms.

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Meningitis

An inflammation of the meninges, the membranes that surround the brain and spinal cord. It's a serious complication of meningococcal disease.

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Shigella

A genus of bacteria responsible for dysentery, which is characterized by diarrhea, abdominal pain, and fever.

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Meningococcal Septicemia

A dangerous condition where the bacteria spread through the bloodstream, causing widespread inflammation and organ damage. Can lead to organ failure and death.

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Yersinia

A genus of bacteria known for their ability to cause gastroenteritis and other diseases, including plague and Yersinia pestis.

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Meningococcal Conjugate Vaccine (MCV4)

A type of vaccine designed to protect against meningococcal disease. Contains capsular polysaccharides from bacteria in serogroups A, C, W-135, and Y.

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Acinetobacter

A genus of bacteria often associated with hospital-acquired infections (nosocomial infections). They are found in the environment and can cause pneumonia, urinary tract infections, and other infections.

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Serogroup B Meningococcal Vaccine (MenB)

A type of meningococcal vaccine that provides protection against serogroup B Neisseria meningitidis.

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Klebsiella

A genus of bacteria that can cause a wide range of infections, including urinary tract infections, pneumonia, and wound infections.

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Enterobacter

A genus of bacteria that can cause various infections, including urinary tract infections, wound infections, and respiratory infections. They are often associated with healthcare settings.

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Moraxella

A genus of bacteria that includes Moraxella catarrhalis. These bacteria are often found in pairs and are generally non-motile and gram-negative.

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Legionella: What is it?

A type of bacteria that causes a respiratory infection. Legionella bacteria are typically found in water sources like showers and hot tubs.

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What causes Brucellosis?

A type of bacteria responsible for causing Brucellosis, a disease transmitted from infected animals (like cows, goats, and pigs) to humans.

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What is Francisella tularensis?

Francisella tularensis is a bacterium that infects animals and can be spread to humans, causing a disease called Tularemia. This infection is often spread through contact with infected animals or by insect bites.

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Pseudomonas aeruginosa: A threat in hospitals

Pseudomonas aeruginosa is a type of bacteria that is known to cause infections, particularly in hospitals. It can be difficult to treat as it is resistant to many antibiotics.

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What is Bacteroides?

Bacteroides is a type of bacteria that can cause peritonitis, an infection of the lining of the abdominal cavity. It is an anaerobic bacteria, meaning it thrives in environments with no oxygen.

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Enterohemorrhagic E. coli (EHEC)

A type of E. coli that causes severe diarrhea with blood in the stool, often associated with contaminated food and water.

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Enterotoxigenic E. coli (ETEC)

A type of E. coli that causes diarrhea in travelers, often due to contaminated food or water.

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Enteroinvasive E. coli (EIEC)

A type of E. coli that causes inflammation in the intestines, leading to bloody diarrhea (dysentery).

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Enteropathogenic E. coli (EPEC)

A type of E. coli that causes diarrhea, especially in infants, due to poor sanitation.

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Enteroaggregative E. coli (EAEC)

A type of E. coli that causes watery diarrhea, especially in travelers. It is known to stick to intestinal cells, making it difficult to get rid of.

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E. coli and Urinary Tract Infections (UTIs)

The most common cause of urinary tract infections (UTIs), including cystitis and pyelonephritis. Women are particularly vulnerable to infection.

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E. coli Strain O104:H4

A special strain of E. coli (O104:H4) that combines traits of both EAEC and EHEC, leading to severe, bloody diarrhea.

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Extraintestinal E. coli Infections

Infections caused by E. coli that occur outside of the intestinal tract, often in sterile areas like the blood or bladder.

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What are the main types of Yersinia bacteria that affect the GI tract?

Yersinia enterocolitica and Yersinia pseudotuberculosis are types of bacteria that can cause gastrointestinal infections.

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What type of Yersinia is responsible for bubonic plague?

Yersinia pestis is the main type of Yersinia responsible for causing the serious infectious disease called bubonic plague.

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To what bacterial family does Yersinia belong?

Yersinia belongs to the family Enterobacteriaceae, which includes many forms of bacteria common in the gut.

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What is the main characteristic of cholera?

Cholera is a severe intestinal disease characterized by profuse watery diarrhea (rice-water stools). Untreated, it can lead to death from dehydration.

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What is Helicobacter and what does it cause?

Helicobacter is a genus of spiral-shaped bacteria that are highly mobile. They are associated with gastritis and ulcers of the stomach and duodenum.

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What is the main clinical significance of Haemophilus influenzae?

Haemophilus influenzae can cause bacterial meningitis, particularly in infants and young children.

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What bacteria causes whooping cough?

Bordetella pertussis is a bacterium responsible for causing whooping cough, a highly contagious respiratory infection.

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What bacterial genus is associated with a type of pneumonia?

Legionella is a genus of bacteria that can cause a type of pneumonia, known as Legionnaires' disease.

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Study Notes

Gram-Negative Bacteria

  • Gram-negative bacteria are a large group of bacteria characterized by their cell wall structure, which distinguishes them from gram-positive bacteria.

Cocci

  • Neisseria:
    • Diplococci (occur in pairs)
    • Gram-negative
    • Aerobic
    • Pathogenic, causing gonorrhea and meningitis.
    • Gonorrhea is a sexually transmitted disease.
    • Meningitis is an inflammation of the membranes surrounding the brain.

Bacilli

  • Straight bacilli:
    • Enteric bacteria (e.g., Legionella, Yersinia, Francisella, Pasteurella, Pseudomonas, Acinetobacter)
      • Some cause intestinal and extraintestinal diseases
  • Curved bacilli:
    • Campylobacter, Helicobacter, Vibrio
      • Campylobacter species cause enteritis and sometimes bacteremia.
      • Helicobacter species cause gastritis and peptic ulcers; are linked to stomach cancer.
      • Vibrio species cause cholera, characterized by profuse watery diarrhea.

Other Gram-Negative Bacteria

  • Moraxella:
    • Nonmotile, gram-negative coccobacilli, usually in pairs
    • Cause infections that include respiratory system, middle ear, eye, CNS, and joints.
  • Acinetobacter:
    • Nonmotile, gram-negative coccobacilli
    • Important nosocomial (hospital-acquired) pathogens.
  • Escherichia coli (E. coli):
    • Part of the normal microbiota of the colon in humans and other animals
    • Can be pathogenic in both the intestinal tract and extra-intestinal sites
  • Enterotoxigenic E. coli (ETEC):
    • A common cause of traveler's diarrhea
    • Transmitted through food, water, and person-to-person contact
  • Enteropathogenic E. coli (EPEC):
    • A significant cause of diarrhea in infants, especially in areas with poor sanitation
  • Enterohemorrhagic E. coli (EHEC):
    • Produces Shiga-like toxin (verotoxin)
    • Causes hemorrhagic colitis with potential for hemolytic uremic syndrome (HUS)
  • Enteroinvasive E. coli (EIEC):
    • Causes a dysentery-like syndrome with bloody stools
  • Enteroaggregative E. coli (EAEC):
    • Causes traveler's diarrhea and persistent diarrhea in young children
  • Urinary tract infections (UTIs):
    • A frequent cause of E. coli infections.
  • Other Gram-negative Rods:
    • Salmonella (gastroenteritis, typhoid fever): food poisoning. -Common cause of food poisoning
    • Shigella (bacillary dysentery): acute gastroenteritis -A common cause of bloody diarrhea -Yersinia (yersiniosis, plague): different diseases in humans; plague can be fatal -Can lead to the potentially fatal plague
    • Legionella (Legionnaire's disease, Pontiac fever): respiratory infections; often transmitted from water sources

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Description

Explore the diverse world of gram-negative bacteria, including their unique cell wall structure and classification. This quiz covers important genera such as Neisseria and various bacilli, focusing on their pathogenic roles and associated diseases. Test your knowledge about these significant microorganisms!

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