Neisseria Spp. Flashcards
What are the general characteristics of Neisseria
GN cocci, diploid, aerobic, oxidase and catalase, non motile and non sporing.
What are the important Neisseria
Meningitidis and gonorrrhoeae
What is the medium that the N. meningitidis
Blood, serum or ascitic fluid
What is the selective medium of the N. meningitidis
Modified Thayer martin
What are the 3 virulence factors?
polysaccharide capsule- enables organisms to resist phagocytosis.
Endotoxin - causes fever shock and pathophysiologic changes
IgA protease- cleaves secretory IgA to attach to the RT capsular Ag
What is the epidemiology of Meningococcal disease?
humans only are the natural host.happens through person to person transmission by aerosolization of respiratory tract secretion in crowded conditions. highest incidence in children younger than 5 years and particularly those younger than 1 year as passive maternal antibody declines and as infants immune system matures.
What is the pathogenesis of Meningococcal disease
Specific receptors (GD1 ganglioside) for bacterial fimbriae on non-ciliated columnar epithelial cells in the nasopharynx of host. organisms are internalized into phagocytic vacuoles. replicate intracellularly and migrate to sub epithelial space where excess membrane fragments are released. Hyper-production of endotoxin and bellowing into surrounding environment.
What are the clinical manifestations of N. Meninigiditis
Cerebrospinal and meningococcal septicemia
What are some of the symptoms of N. Meninigitidis
acute fever, chills, malaise and prostration, petechial rash, metastatic involvement. bleeding into the brain and adrenal
What is Waterhouse- Friderichsen syndrome
defined as adrenal gland failure due to bleeding into the adrenal glands, commonly caused by severe bacterial infection: Typically the pathogen is the meningococcus Neisseria meningitidis.[1]The bacterial infection leads to massive hemorrhage into one or (usually) both adrenal glands.[2] It is characterized by overwhelming bacterial infection meningococcemia leading to massive blood invasion, organ failure, coma, low blood pressure and shock, disseminated intravascular coagulation (DIC) with widespread purpura, rapidly developing adrenocortical insufficiency and death.fatal causes shock, disseminated intravascular coagulation and system failure.
What are the lab diagnosis of N, meningitides
CSF examination: has 3 portins
used for gram staining
culture on B/A or C/A incubate at 35 to 26C under 5 to 10%CO2. colonies after overnight incubation are studies for morphology and biochemical reaction.
incubate as it is or with glucose broth and then S/C onto C/A
How is it on blood culture? it is often positive and is kept for 4 to 7 days
what else can be done? nasopharygenal swab, petechial lesion and autospy
What is the treatment and prophylaxis?
intravenous penicillin G is treatment along with chloramphenicol are effective. before etiology you can use ceftriaxone and ceftazidmie.
nasopharynx treatment- rifampicin or ciprofloxacin. also vaccines of capsular polysaccharides of A,C,W-135 and Y can help.
What are the characteristics of N. Gonorrhoaeae
GNDC- has pili for adhesion, aerobic. grows on chocolate agar and MHA. selective medium TMM (thayer-martin) transmitted sexually. newborns can be infected at birth and the women are not symptomatic but men are.
What virulence Factors of N.Gonorrhoeae
Pilin, Por protein, Opa protein, Rmp protein, Transferrin binding, lactoferrin, hemoglobin binding, Hemoglobin binding, LOS, IgA protease, Beta- lactamase
What are features of Gonorrhea?
venereal disease that incubates for 2-10 days. men tend to have acute arthritis with mucopurulent discharge. spread of infection: multiple discharging sinuses ( water-can perineum)
women: urethra and cervix uteri, PID and salpingitis, peritonitis with perihepatic inflammation. conjunctivitis, hematogenous spread. Peritonitis with perihepatic inflammation ( fitz-hugh Curtis syndrome)
