Bacterial Disease and Virulence Factors

Vocabulary flashcards covering key terms related to bacterial disease, virulence factors, and specific bacterial infections like Meningococcal Disease and Haemophilus influenzae type b (Hib).

Biofilms

A tough bacterial infection formed when a quorum of bacteria produces a matrix, enabling them to cling together and become difficult to remove.

Quorum

A group of bacteria in sufficient numbers that collectively turn on functions to support the colony rather than individual bacteria, such as biofilm production.

Bacterial Disease

Caused by damage from bacteria and the host's innate and adaptive immune responses, with signs and symptoms depending on the affected tissue.

Length of Incubation

The time required for bacteria or the host response to cause sufficient damage to initiate discomfort or interfere with essential functions.

Exotoxins

Proteins produced inside pathogenic bacteria and then secreted into the surrounding medium, which can damage host tissues.

Endotoxins

Constitutive elements of the bacterial membrane (lipids) that are only liberated and cause damage when the bacteria die.

Superantigens

Toxins that bypass normal antigen presentation and directly activate a large fraction of T cells, leading to an excessive immune response.

Meningococcal Disease

A severe illness, often a main cause of meningitis in young adults, with peak incidence among college students.

Neisseria meningitidis

A Gram-negative, encapsulated, aerobic diplococcus bacteria, divided into serotypes, which is a common cause of meningococcal disease.

Diplococcus

A type of bacteria characterized by a spherical shape and occurring in pairs.

Gram-negative bacteria

Bacteria that do not retain the crystal violet stain in the Gram staining procedure and appear red/pink, characterized by a thin peptidoglycan layer and an outer membrane.

Serotypes (Bacterial)

Distinct variations within a species of bacteria identifiable by different antigens that can be targeted by specific antibodies.

Neisseria meningitidis Transmission

Occurs through aerosol droplets or direct contact, such as kissing, with carriage rates higher among adolescents and young adults.

Meningitis

An inflammation of the membranes surrounding the brain and spinal cord, characterized by symptoms like fever, stiff neck, headache, confusion, photophobia, and nausea/vomiting.

Meningococcemia

A severe form of sepsis caused by Neisseria meningitidis, affecting 10-20% of patients with meningococcal disease, often accompanied by a rash.

Nuchal rigidity

Stiffness of the neck, often associated with meningitis, making it difficult to flex the neck forward.

Pathogenesis of Meningococcal Disease

Involves attachment to pharyngeal mucosal cells, replication, entry into the bloodstream, rapid bacterial doubling, release of endotoxins, and an immune system response involved in bacterial clearance.

Hib bacteria (Haemophilus influenzae type b)

A Gram-negative coccobacillus, with serotype b being the most important in human pathogenesis, particularly for meningitis and septicemia, mainly affecting children under 5.

Serotype b (of Hib)

The most important serotype of Haemophilus influenzae in human pathogenesis, distinguished by its polysaccharide capsule, a major virulence factor.

Polysaccharide capsule (Hib virulence factor)

A major virulence factor for Hib bacteria, providing a protective layer of sugars that enhances survival in the bloodstream and helps evade immune cells.

Pathogenesis of Hib infection

Involves entry into the respiratory tract, colonization of mucosa, potential symptom-free carriage, and disease development at distal sites once bacteria enter the bloodstream, causing illnesses like meningitis, cellulitis, pneumonia, and arthritis.

Hib-related illnesses

Include meningitis (most common), pneumonia, severe throat swelling, and infections of the blood, joints, bones, and heart.

Hib Vaccine

A highly effective vaccine for Haemophilus influenzae type B, typically given in doses at 2, 4, 6, and 12-15 months, available as a standalone vaccine or combined with others (tetanus, diphtheria, whooping cough, polio).

Hib virulence factor

Polysaccharide capsule

Sequelae

A condition that is a consequence of previous disease or injury

Meningococcal disease clinical manifestation

Fever

Headache

Stiff neck

Confusion

Increased sensitivity to light

Nausea

Vomiting