Gram-Negative Bacteria Overview
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Questions and Answers

What disease is primarily associated with the genus Brucella?

  • Pneumonia
  • Whooping cough
  • Undulant fever (correct)
  • Tularemia

Which organism is known for causing a mild pertussis-like illness?

  • Legionella
  • Bordetella (correct)
  • Pseudomonas aeruginosa
  • Francisella tularensis

Which of the following pathogens is primarily responsible for hospital-acquired infections?

  • Brucella
  • Pseudomonas aeruginosa (correct)
  • Francisella tularensis
  • Legionella

Which pathogen is primarily a respiratory tract infection agent?

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

Which species of Brucella is specifically associated with swine?

<p>B. suis (C)</p> Signup and view all the answers

What is a common symptom of gonococcal infection in males?

<p>Yellow, purulent urethral discharge (D)</p> Signup and view all the answers

What complication can occur in women due to gonococcal salpingitis?

<p>Tubal scarring leading to infertility (D)</p> Signup and view all the answers

What is the primary treatment for ophthalmia neonatorum?

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

What bacterium is frequently associated with severe epidemics of meningitis in developing nations?

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

Which symptom is characteristic of meningococcemia caused by N. meningitidis?

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

In which situations are outbreaks of meningitis caused by N. meningitidis most commonly favored?

<p>Close contact situations like schools and barracks (D)</p> Signup and view all the answers

What is the most common type of discharge seen in females with gonococcal infection?

<p>Greenish-yellow cervical discharge (C)</p> Signup and view all the answers

What can untreated acute conjunctivitis in newborns lead to?

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

Which species of Neisseria is known to cause meningitis?

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

What type of bacteria is Neisseria gonorrhoeae classified as?

<p>Gram-negative diplococcus (C)</p> Signup and view all the answers

Which is a common mode of transmission for Neisseria gonorrhoeae?

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

Which of the following is NOT a characteristic of Neisseria species?

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

From which type of cells is Neisseria gonorrhoeae often observed in clinical samples?

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

Which gram-negative organism is known for causing infections primarily in humans?

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

What characteristic feature differentiates gonococci from meningococci under the microscope?

<p>They cannot be distinguished (A)</p> Signup and view all the answers

What is the primary significance of Neisseria meningitidis in public health?

<p>It is a frequent cause of meningitis. (C)</p> Signup and view all the answers

What is a major cause of neonatal meningitis occurring within the first month of life?

<p>E.coli (B)</p> Signup and view all the answers

Which of the following symptoms is NOT typically associated with salmonella gastroenteritis?

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

Which type of fever is primarily caused by serotype typhi?

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

What is the mortality rate approximately associated with enteric (typhoid) fever?

<p>15% (A)</p> Signup and view all the answers

Which bacterium is known for causing shigellosis or bacillary dysentery?

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

Which of the following is a characteristic symptom of shigellosis?

<p>Diarrhea with blood and mucus (C)</p> Signup and view all the answers

Which genus is characterized by curved, spiral, or S-shaped organisms?

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

What type of infections can members of the genus Vibrio cause?

<p>Intestinal and extraintestinal infections (B)</p> Signup and view all the answers

Which of the following organisms are primarily responsible for gastrointestinal diseases?

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

What feature is common among enteric gram-negative rods found in the GI tract?

<p>They contain lipopolysaccharide (LPS). (C)</p> Signup and view all the answers

Which of the following organisms can be classified as an opportunistic pathogen?

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

Which characteristic is important for E. coli adherence to host mucosal surfaces?

<p>Fimbriae or pili (C)</p> Signup and view all the answers

What is a common mode of transmission for GI diseases caused by certain pathogens?

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

Which genus is primarily gastrointestinal and does not typically cause extraintestinal diseases?

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

What type of bacteria are members of the genus Acinetobacter?

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

Which of the following diseases is NOT typically caused by organisms primarily found in the GI tract?

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

What is the primary virulence factor of N. meningitidis?

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

Which population is particularly susceptible to N. meningitidis infections?

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

What severe symptom can develop quickly due to meningococcal infection?

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

How quickly can meningococcal septicemia occur in a healthy individual?

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

What type of vaccine replaced the quadrivalent polysaccharide vaccine for meningitis prevention in U.S. adolescents and adults?

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

Which of the following meningococcal vaccines is specifically designed for serogroup B?

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

What is a common presentation in patients with meningococcal infections aside from fever?

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

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

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

Flashcards

What are Legionella bacteria?

Bacteria in the genus Legionella are facultative intracellular parasites, meaning they can live and reproduce both inside and outside of host cells. They primarily cause infections of the respiratory tract, leading to pneumonia, a lung inflammation.

What is Pseudomonas aeruginosa?

Pseudomonas aeruginosa is a widespread bacterium, frequently found in natural environments. It is a significant opportunistic pathogen, particularly in hospitals, where it often causes nosocomial infections - infections acquired during a hospital stay.

What are Brucella bacteria?

Brucella species are primarily pathogenic to animals, infecting both domestic and wild creatures. Brucellosis (undulant fever), a zoonotic disease, can be transmitted from animals to humans. Different Brucella species target specific animal hosts.

What is Francisella tularensis?

Francisella tularensis is a bacterium mainly affecting animals. Tularemia, also known as rabbit fever or deerfly fever, is a zoonotic disease that can spread to humans.

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What are Bacteroides bacteria?

Bacteroides bacteria are a common cause of peritonitis, an inflammation of the peritoneum, the lining of the abdominal cavity. These bacteria are anaerobic, meaning they cannot survive in the presence of oxygen.

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Neisseria meningitidis

A type of bacteria that causes meningitis and septicemia, often in young, previously healthy individuals.

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Meningococcal Polysaccharide Capsule

The capsule surrounding the meningococcus bacteria that protects it from being engulfed by white blood cells.

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Meningitis

Inflammation of the meninges, the membranes that surround the brain and spinal cord. It can be caused by bacteria like N. meningitidis.

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Meningococcal Septicemia

A serious infection of the bloodstream that can be caused by N. meningitidis. It can quickly progress to a life-threatening condition.

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Meningococcal Vaccines

Vaccines that specifically target N. meningitidis. They contain components of the bacteria's capsule to stimulate an immune response.

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Meningococcal Conjugate Vaccine (MCV4)

A type of meningococcal vaccine that contains polysaccharide capsules from serogroups A, C, W-135, and Y.

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Meningococcal Disease

A condition caused by N. meningitidis bacteria that can range from mild throat infection to severe meningitis and septicemia.

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Moraxella

A type of bacteria that typically resides in the throat but under certain conditions can spread to other parts of the body.

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Neisseria

A genus of gram-negative, aerobic cocci, with two notable species pathogenic to humans: Neisseria gonorrhoeae (gonococcus), causing gonorrhea, and Neisseria meningitidis (meningococcus), often causing meningitis.

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Neisseria gonorrhoeae (Gonococcus)

A gram-negative diplococcus, often found inside white blood cells in clinical samples of infected individuals. It is the cause of gonorrhea, a common infectious disease.

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Neisseria meningitidis (Meningococcus)

A gram-negative diplococcus that can cause bacterial meningitis. It is often found in the cerebrospinal fluid of infected individuals.

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Gonorrhea

A common infectious disease caused by Neisseria gonorrhoeae. It is usually spread through sexual contact or during childbirth.

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Coccobacilli

A type of gram-negative bacteria shaped like short rods or ovals. They are often found in pairs.

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Bacilli

A type of gram-negative bacteria shaped like long rods.

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Facultative anaerobes

A type of bacteria that can grow with or without oxygen. They can switch between using oxygen for energy and living in anaerobic conditions.

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Anaerobes

A type of bacteria that can only survive in environments without oxygen. They are poisoned by oxygen.

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Salmonella

A type of bacteria that can cause a variety of diseases, including gastroenteritis and typhoid fever.

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Shigella

The genus of bacteria that causes shigellosis, often seen in children.

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Typhoid fever

A severe, life-threatening illness caused by Salmonella typhi, characterized by fever and gastrointestinal symptoms.

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Campylobacter

A common type of bacteria found in the gut, often causing gastroenteritis. It can also infect other parts of the body, leading to bacteremia.

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Salmonella infection

A bacterial infection that can cause both intestinal and extraintestinal illness. It's characterized by nausea, vomiting, diarrhea, and abdominal cramping.

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Vibrio

A genus of bacteria that is curved and rod-shaped. It's known for causing infections in the digestive system.

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Neonatal meningitis

A type of infection that develops in the first month of life and can be caused by various bacteria including E. coli.

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Nosocomial infections

Infections acquired during a hospital stay. Common examples include sepsis, endotoxic shock, and pneumonia.

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Acinetobacter

A genus of bacteria that are nonmotile coccobacilli, often found in hospital environments and causing nosocomial infections.

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Enteric Gram-negative Rods

Gram-negative bacteria that thrive in the gastrointestinal tract, contributing to the gut microbiome.

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Enterobacteriaceae

A family of bacteria including various genera, some causing gastrointestinal diseases, others primarily affecting areas outside the gut, and some impacting both.

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E. coli (Escherichia coli)

A common inhabitant of the colon, but can also cause infections both inside and outside the digestive system. It contributes to the gut microbiome.

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Yersinia

A genus of bacteria known for causing various diseases, including plague and gastrointestinal infections.

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What are pili?

Tiny hair-like structures found on the surface of some bacteria. They help the bacteria attach to surfaces like host cells and tissues.

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What is gonorrhea?

Neisseria gonorrhoeae is a bacterium that causes sexually transmitted infections (STIs). The infection is more easily diagnosed in men due to clear symptoms like a yellow discharge and painful urination. In women, the infection can spread to the uterus, fallopian tubes, and lead to pelvic inflammatory disease (PID).

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How does gonorrhea affect fertility?

Infection with Neisseria gonorrhoeae can lead to inflammation of the fallopian tubes, which can cause scarring and potentially lead to infertility in women.

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What is ophthalmia neonatorum?

Ophthalmia neonatorum is an eye infection that occurs in newborns during birth if the mother has gonorrhea. The infection can lead to blindness if left untreated.

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What is Neisseria meningitidis?

Neisseria meningitidis is a bacteria that causes meningitis, a serious infection of the membranes around the brain and spinal cord. It can also lead to a severe bloodstream infection called meningococcemia, which can cause organ damage and death.

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When are outbreaks of meningitis more common?

Meningitis caused by Neisseria meningitidis is often more common during winter and early spring, especially in places where people are close together like schools and military barracks.

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What is meningococcemia?

Neisseria meningitidis can cause a severe bloodstream infection called meningococcemia, which can lead to organ damage and death. This occurs without meningitis and can be life-threatening.

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How does Neisseria gonorrhoeae survive?

Neisseria gonorrhoeae is highly sensitive to dehydration and cannot survive long outside the human body. It is primarily transmitted through sexual contact.

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Study Notes

Gram-Negative Bacteria

  • Gram-negative bacteria are a diverse group of microorganisms.
  • They are categorized by morphology (cocci or bacilli) and further classified as straight or curved.
  • Straight bacteria include Enteric bacteria, Legionella, Yersinia, Francisella, Pasteurella, Pseudomonas, and Acinetobacter.
  • Curved bacteria include Campylobacter, Helicobacter, and Vibrio.

Cocci

  • Gram-negative cocci bacteria are often grouped together as diplococci.
  • Neisseria is a genus of Gram-negative diplococci.
  • Infections caused by Neisseria include gonorrhea and meningitis.
  • Neisseria species can be identified as gram-negative diplococci.

Rods (bacilli)

  • Gram-negative bacilli are a category of bacteria.
  • Gram-negative rods are commonly separated into aerobic and anaerobic groups.

Overview

  • The genus Neisseria consists of gram-negative, aerobic cocci.
  • Two Neisseria species are pathogenic for humans: N. gonorrhoeae and N. meningitidis.
  • Gonococci and meningococci are nonmotile diplococci.

Gonorrhea

  • Gonorrhea is a sexually transmitted infection (STI) and a common disease.
  • The causal agent is Neisseria gonorrhoeae.
  • The infection typically involves the urethra and vagina.
  • Infections in both genders manifest differently.

Meningitis

  • Meningitis caused by N. meningitidis is a serious condition.
  • The symptoms appear quickly and include severe headaches.
  • The organism spreads from the throat into the bloodstream.

Clinical Significance

  • N. meningitidis initially colonizes the nasopharynx causing pharyngitis.
  • It can lead to meningitis and/or fulminating septicemia.
  • N. meningitidis currently remains a major cause of meningitis.

Other E. coli infections

  • Enteroinvasive E. coli (EIEC) exhibit a dysentery-like syndrome.
  • Enteroadherent E. coli (EAEC) cause traveler's diarrhea or persistent diarrhea in young children.

UTI-causing organisms

  • E. coli is the leading cause of UTIs.
  • Other Gram-negative bacteria are also involved in UTIs.

Neonatal meningitis/Nosocomial infections

  • E. coli is one of the major causes of neonatal meningitis.
  • Nosocomial infections are infections originating in hospitals or other healthcare settings.

Helicobacter pylori

  • They are curved or spiral-shaped rods.
  • Helicobacter pylori cause gastritis and stomach ulcers.
  • They are also known to potentially cause stomach cancer.

Respiratory Organisms

  • Haemophilus can cause meningitis.
  • Bordetella causes whooping cough.
  • Legionella causes pneumonia.

Gram-Negative Rods Associated with Respiratory Tract

  • Haemophilus influenzae causes meningitis, otitis media, sinusitis, pneumonia and epiglottitis.
  • Bordetella pertussis causes whooping cough.
  • Legionella pneumophila causes pneumonia

Anaerobic Gram-negative Rods

  • Bacteroides are among the bacteria frequently found in the human gut and involved in peritonitis.

Diseases caused by Gram-Negative Rods

  • Escherichia-related infections.
  • Salmonella causes gastroenteritis and typhoid fever.
  • Campylobacter infections (e.g. enteritis).
  • Shigella leads to shigellosis or bacillary dysentery.
  • Vibrio is associated with cholera.
  • Yersinia-related diseases.
  • Pseudomonas can cause infections.

Zoonotic Organisms

  • Pathogens from animals are often transmitted to humans through contact, contaminated food or water.
  • Brucella is a common zoonotic disease.
  • Other zoonotic diseases like tularemia and pasteurellosis are caused by pathogens spread by animals.

Vaccines

  • Meningococcal conjugate vaccines are available and used in adolescents and adults.
  • Vaccination schedules are in place for preventative measures.

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This quiz focuses on the classification and characteristics of gram-negative bacteria, including their morphological types such as cocci and bacilli. Key genera like Neisseria and their associated infections are highlighted. Test your knowledge of these microorganisms and their significance in human health.

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