Lecture 8 Flashcards
What are Parvobacteria?
Parvobacteria are bacilli that are so short that they are often confused with cocci.
What is the natural habitat of Neisseria?
Neisseria is part of the natural flora in the human nasopharynx and genitourinary tract.
Give examples of Neisseria.
Examples of Neisseria are Neisseria meningitidis and Neisseria gonorrhoeae.
What is the peak age for Neisseria disease occurrence?
Neisseria Disease occurs in infants and at a second peak at approximately 18 years.
What are the symptoms of Neisseria disease?
Symptoms of Neisseria disease include acute meningitis, fever, headache, seizures, mental signs, intracranial pressure, rash, purpura, and thrombocytopenia.
What is the initial step in meningococcal pathogenesis?
The initial step in meningococcal pathogenesis is colonization of the nasopharynx by the bacteria.
How do meningococcal bacteria attach to the epithelial cells of the nasopharynx?
: Meningococcal bacteria attach to the epithelial cells of the nasopharynx via pili and other adhesins.
What is the role of outer membrane proteins in meningococcal pathogenesis?
Outer membrane proteins facilitate the invasion of meningococcal bacteria by allowing them to adhere to and penetrate endothelial cells.
What is the purpose of capsule of n.meningitidis?
The polysaccharide capsule of n.meningitidis prevents phagocytosis.
What is the basis of classification into 13 serogroups for n.meningitidis?
The polysaccharide capsule is the basis of classification into 13 serogroups for n.meningitidis.
Which serogroups of n.meningitidis cause the majority of disease?
The majority of disease caused by n.meningitidis is due to serogroups A, B, C, W-135, and Y.
Is there a vaccine available for serotype B of n.meningitidis?
Vaccination against serotype B of n.meningitidis is difficult due to the presence of sialic acid on the serotype, similar to that found on host cells.
What is the pathogenesis of Neisseria gonorrhoeae?
The pathogenesis of Neisseria gonorrhoeae involves adherence to the mucosal surface of the urogenital tract using fimbriae, invasion of the epithelial cells of the mucosa, triggering of an inflammatory response, dissemination to other parts of the body, and ingestion by macrophages and PMNs.
Which media is used to culture N. meningitidis?
: N. meningitidis is usually cultured from sterile body fluid such as CSF or blood, so no other organism can overgrow.
Which media is used to culture N. gonorrhoeae?
N. gonorrhoeae is usually grown on chocolate agar with antibiotics because the sample is taken from an area with a lot of normal flora.
How does Neisseria avoid surface immune response?
Neisseria avoids surface immune response through antigenic variability and IgA protease.
What is the treatment for N. meningitidis and N. gonorrhoeae infections?
N. meningitidis is treated with Cephalosporins which are often the first choice drug, while newer cephalosporins are used for N. gonorrhoeae as it produces beta-lactamases.
What is the characteristic feature of Moraxella catarrhalis?
Moraxella catarrhalis produces DNAse, indicating the absence of carbohydrates.
What is the primary reservoir for Haemophilus influenzae?
The human respiratory tract is the primary reservoir for Haemophilus influenzae, with 20-50% of people being carriers.
Which Haemophilus species cause sexually transmitted disease?
H. ducreyi is the Haemophilus species that causes sexually transmitted disease in the tropics.
What are the two types of disease h,influ causes and example?
H.infl causes Invasive disease: Meningitis, pneumonia, epiglottitis, bacteraemia cellulitis and Non- invasive disease-Otitis media, conjunctivitis
What are h.influ antigenic types based on ?
H.infl has Six antigenic types based on polysaccharide capsular antigen (a-f)
What is the H.influ vaccine based on and when is it given?
Capsule based vaccine used to immunise children against H.infl (>24mths)
Pathogenesis of h.influ?
The first step in the pathogenesis of H. influenzae is adherence to the respiratory epithelium, pili and outer membrane proteins. Colonize the mucosa. The bacteria produce several factors that help them survive in this environment, including type b capsule, lipooligosaccharides, and adhesins, that facilitate invasion. The type b capsule is particularly important in invasion, as it helps protect the bacterium from phagocytosis by host immune cells. It triggers an inflammatory response. The host immune system produces cytokines and chemokines that recruit immune cells to the site of infection. Neutrophils are the primary immune cells that are recruited, and they play an important role in clearing the bacterium from the host tissue. also cause tissue damage. The release of inflammatory mediators, such as reactive oxygen species and proteases, can damage host tissue and contribute to the symptoms of infection, such as fever and inflammation.
