7 - Bacterial CNS and STDs Flashcards
What can lead to acute infection from Neisseria meningitidis? How is it spread?
Acute infection can follow mildly symptomatic or asymptomatic nasopharyngeal carrier state.
Transmitted via aerosolized droplets.
What are characteristics of an acute infection caused by Neisseria meningitidis?
Abrupt onset, chills, fever, severe headache ., cervical and thoracolumbar rigidity.
Altered mental status and photophobia
Hemorrhagic spots, purpura.
How would you do a laboratory diagnosis of Neisseria meningitidis? What is it’s physiology and structure?
Gram stain the CSF: N. meningitidis is a gram negative diplococci with lipooligosaccharide (LOS).
Blood culture.
Oxidase test - they are oxidase +
Does iron uptake
What are the serotypes of N. meningitidis? What structures does it have?
A, B, C, Y, and W135
Has porins A and B, pilli, and a polysaccharide capsule used for serotype designation.
What is the pathogenesis of Neisseria meningitidis?
- Attach to columnar epithelial cells of nasopharynx via pili.
- Internalized into phagocytic vacuoules
- Replication and transcytosis into subepithelial space
- Capsule is major virulence determinant that blocks phagocytosus
- LOS induced vascular damage, inflammation of vessel walls, and thrombosis and IV coagulation.
What is the endemic epidemiology of Neisseria meningitidis? Describe carriage?
Humans only reservoir, many people are asymptomatic carriers (highest for high school age and young adults)
Carriage is transient and clearance correlates with developing Ab specific to capsular polysacc.
Neisseria meningitidis is _____, but most common during ____ months.
Sporadic, most common during dry cold months of the year.
What and where is the menengitidis belt? Which sero group is associated with most epidemics?
Major epidemics on an 8-12 year cycle in sub-saharan Africa during the dry season june-dec.
Most epidemics associated with serogroup A.
What vaccination is available for Neisseria meningitidis?
Serogroup tetravalentvaccine for A, C, Y, and W135 for people >55 for short-term immunity
Tetravalent vaccine-conjugate diptheria toxoid
Epidemic strains in Africa, WHO approved vaccine for $0.5/dose, sero group A conjugate.
What is the drug treatment for Neisseria meningitidis?
Cefotaxime
Ceftriaxone
Penecillin G
What is the prophylaxis for Neisseria meningitidis or for people exposed to pts with disease >8hrs?
Rifampin
Ciprofloxacin
Ceftriaxone
Why don’t any of the vaccine include serotype group B meningitidis? What is the new vaccine to cover group B made from?
Polysaccharide is a polymer of sialic acid which is similar to fetal neuronal tissue - poorly immunogenic.
Vaccine based on whole genome sequencing and identification of surface antigens - called 4CMenB - and contains 2 components of the group B bacterium
According to the CDC, who should get the quadrivalent conjugate vaccine that protects against serogroups A, C, W, and Y?
Travel to sub-saharan africa, military recruits, college freshman, individuals that research N. mengitidis, those with complement deficiency, prolonged contact with active case, and asplenic ppl.
According to the CDC, who should get the meningicoccal polysaccharide vaccine?
Older than 56, traveling or residing in countries in which disease is common, or you’re part of a population identified to be at increased risk due to an outbreak.
According to the CDC, who should get the serogroup B meningococcal vaccine?
Those with complement component deficiency or are taking soliris, damaged spleen, microbiologict working with N. menengitidis, or are in an population at risk due to a group B outbreak.
What CNS infections are neonates, children, and adults each most susceptible to?
Neonates: streptococci groups A, B, E. coli K1 capsule (group B meningitidis)
Children: H. influenza, N. meningitidis
Adults: N. meningitidis, S. pneumoniae
What are key characteristics of Neisseria gonorrhea? What does it eat? What is it sensitive to?
Gram negative diplococcir, oxidase +
Human specific pathogen that requires cysteine, aas, purines, and pyrimidines.
Sensitive to cold.
It has a pili for twitching motility and resistance to neutrophils.
How does Neisseria gonorrhea differ from N. menengitidis? How is it similar in structure?
It does NOT posses a polysaccharide capsule.
It has a pili.
What gonococcal antigen interferes with PMN degranulation, facilitates bacterial invasion, and provides resistance to complement?
Porins: OM proteins that form pores for nutrient uptake;
N. gonorrhoeae has porB.
Besides porB, what are three other important gonococcal antigens?
Opa proteins: mediate binding to epithelial cells
Receptors for human transferrin: mediate iron uptake in host
LOS: lipooligosaccharide
What is the pathogenesis of gonococci?
Acquired via sexual contact and attachment to non-ciliated epithelial cells; transcytosis to subepithelial spaces.
Replication and release of LOS/LPS causes inflammatory response and damage to urethral or vaginal epithelium.
Can infect new person via carry over through immune cells such as neutrophils.
Why is their no vaccine for gonococci?
It doesn’t have a capsule and it has highly variable surface proteins making it hard to create a vaccine that will remain effective.
What is a major reservoir of gonococcal infection? What do the epithelial sites of infection include?
Asympotomatic carriers. Most common in women than men.
Sites of infection include pharynx and rectum.
What is the clinical presentation of gonorrhea in men and women? How can babies get this?
Men: purulent urethral discharge and dysuria 2-5 days post exposure. 95% sympomatic
Women: primary site of infection is cervix/endocervical columnar epithelium. Vaginal discharge, dysuria and abdominal pain. 10-20% ascending infection.
Babies can get ophthalmia neonatorum from exposure during vaginal birth.
How would you get a lab diagnosis of Neisseria gonorrhea?
Gram stain: gram - diplococci within polymorphonuclear leukocytes
Selective medium for culturing
Nucleic acid amplification assay, especially when combined as a multiplex assay for gonorrhea and chlamydia
What is the 1st and 2nd line of therapy for Neisseria gonorrhea?
1st line: Dual therapy with ceftriazone and azithromycin
2nd: cefixime and either azithromycin or doxycyclin
What are the physiological characteristics of chlamydia?
Usually gram - envelope with LPS.
Do not make PG - no cell wall and not susceptible to B-lactams.
What is the life cycle of chlamydia?
Elementary body (EB): infectious form stable in environ b/c of cross-linked OM structure
Reticulate body (RB): replicative intracellular form, metabolicallty active and osmotically fragile, not stable in environ. Replicate by binary fission within the inclusion body.
Chlamydia interferes with normal _____ _____ and replicate within the protective environment of the ____ _____.
Endocytic trafficking
Inclusion body
What are characteristics of chlamydia trachomatis LGV infections?
EB mediates attachment to nonciliated columnar or transitional epithelium
Transcytosis and entry into monocytes and macrophages
Transforms to RB and replicates within immune cells.
Transforms back to EB and spreads/causes inflamm.
What can result from chlamydia trachomatis LGV infections that go untreated?
Go into chronic ulcerative phase with gential ulcers and fistulas.
What is the most common bacterial sexually transmitted disease in the US? How many people reported having it in 2010? How many women are asymptomatic?
chlamydia trachomatis
1.3 mil cases in 2010 (serotypes D-K mostly);
80% women asymptomatic; 25% men asymptom.
What is Reiter syndrome?
Occurs in young caucasion males, 80% have evidence of chlamydia trachomatis infection.
Urethritis, conjunctivitis, polyarthritis, mucocutaneous lesions.
What is trachoma? Where is it endemic?
Chronic keratoconjunctivitus caused by serotypes A, B, Ba, and C of chlamydia trachomatis.
Endemic to north and sub-saharan africa, middle East, south asia, and south americca.
What can result from chlamydia trachomatis infections?
How is it spread? Who gets it?
Follicular conjunctivitus, inflammation, eyelashes turn inward and abrade cornea. Scarring, invasion of blood vessels, and loss of vision.
Infected droplets, contact with contaminated materials. Can be spread during vaginal delivery. (occurs mostly in children w/ crowded living conditions)
What is the lab diagnosis for chlamydia?
Specimens of squamocolumnar endocervical cells. Look for inclusion boddies within cells.
Antigen detection via antibodies specific for major OM protein or chlamydial LPS.
Nucleic acid amplification - sensitive and speicific
