Micro J210 Vaccines/Meningitis
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What is the vaccination impact?
- -Most important weapon against infection that we have
- -Much better than antibiotics
- -Vaccines present multiple foreign antigen to the host immune system
- -Many vaccines use to be diseases that cause problems and still cause problems today.
- -#2 Strep pneumonia, #3 measles
What is a live attenuated vaccines?
- -Contain bacteria or viruses that have been altered (weakened by passage through eggs, cells in cultures or other hosts) so they can cause mild disease which leads to immunity
- -MMR: viral vaccine
- -BCG: (Bacilius, Calmette, Guerin): Mycobaterium bovis, cowpox instead of mycobacterium TB (small pox)
What are heat or chemically killed vaccines?
- -Contain killed bacteria or inactivated viruses
- -Influenza vaccine, Bordetella Pertussis vaccine
What are purified component/subunit vaccine?
- Contain inactivated toxin (toxoid) that are produced by the microbe or purified surface component of the microbe that have been made harmless
- -Corynebacterium diphtheria toxoid vaccine (DPT)
- -Clostridium tetani toxoid vaccine (DPT)
- -Pneumoccal capsular vaccine (PPV), pool of 90 different types of purified capsules
What are recombinant vaccines?
- Genes for desired antigens are inserted into a vector, usually a virus that has a very low virulence. The vector expressing the antigen may be used as the vaccine, or the antigen may be purified and injected as a subunit vaccine
- -Hep B Virus (HBV) vaccine, a recombinant subunit vaccine
What is herd immunity or community immunity?
- -Refers to a reduction in the probability of infection of susceptible members of a population when a significant proportion of the individuals are immune
- -This reduction is observed because the chance of coming in contact with an infected individual is less. In other words, disease transmission is blocked when a critical percentage of the percentage of the population has been vaccinated
- -Measles viral vaccine is only 90% effective but other 10% are protected because virus is not being spread around
- -Depending on the disease, need to vaccinate 75-95% of population to induce herd immunity
What information is contained in the MMWR?
Death rates and vaccines
What is Pertussis?
- -Whooping cough
- -Gram negative, coccobaillus with a capsule.
What is the pathology of pertussis?
- -Highly contagious bacterial infection that causes a severe cough
- -Major cause of morbidity and mortality among infants and children in the US during the 1940s
- -Infants less than a 1 are most susceptible, not a lot of antibodies
- -Binds to ciliated epithelial cells, and releases toxin and damages cells.
What are the symptoms of pertussis?
- -Disease start with symptoms similar to common cold
- -Whooping cough (paroxysms) cause lack of oxygen. Gagging and vomiting may occur after severe coughing spells. May be worse at night and lead to death
What is the DTP vaccine?
- -1942 American scientist Pearl Kendrick combined the whole-cell pertussis vaccine with diphtheria and tetanus toxoids to make DTP.
- The pertussis portion of DTP shot was killed B. pertussis bacteria
- -Though effective, the P vaccines caused unwanted neuro side effects
What happened after the DTP vaccine?
- -Vaccine discomfort permeated the publics state of mind during the late 1970s/1980s. Vaccinations dropped and pertussis causes rose!
- -This started DTap, acellular (toxoid and component) were developed
- -The first DTap, approved in 1991 and was shown to be just as effective with no major side effects.
- -DTP removed from American market in 2001
What is the biology of Corynebacterium Diphtheriae?
-Gram positive bacillus, with cell sticking together to odd shapes called chinese letter appearance
What is the pathology of diphtheria?
- -Very contagious and potentially life-threatening infection that usually attacks the throat and nose. More serious can attack the nerves and heart
- -Bacteria live in upper respiratory tract, person to person transmission via droplets
- -During its growth, produces a toxin that is carried in the bloodstream
- -Coded by a bacteriophage called corynephage which gives the bacteria the extra gene to produce the toxin.
- -Toxin inhibits protein synthesis of hose cells and may damage heart and nervous system
What are the symptoms of diphtheria?
- -Early symptoms are sore throat and mild fever which progresses to lymphadenopathy of the neck and a pseudomembrane that forms over the throat and tonsils that make it hard to swallow
- -Can lead to asphyxiation.
What is the vaccine of diphtheria?
- -Toxoid of organism
- -Protects almost everyone who has received full series of recommended doses. The number of people with diphtheria has fallen from 206,939 in 1921 to only a few year in the US
What is the biology of Clostridium Tetani?
- -Gram positive, anaerobic (loves necrotic tissue), spore forming rods
- -Hardy spores survive in harsh conditions (soil)
- -Spores germinate in suitable environments (wounds)
- -Tennis racket morphology of organism.
- -Needs to be killed in an autoclave
What is the pathology of c. tetani?
- -Tetanus is the only vaccine preventable disease that is not communicable but acquired through environmental exposure to the spores of C. tetani
- -Disease is caused by action of very potent neurotoxin produced during the anaerobic growth of the bacterium in necrotic tissues (dirty wounds) or from the umbilicus following non-sterile delivery.
What are the symptoms of tetani?
-Muscle spams, initially muscles of mastication causing trismus or lockjaw, which results in characteristic facial expression
What is the DTaP schedule?
- -4 childhood shots: 2, 4, 6 , 15-18 months
- -Fifth dose: 4-6 years
- -Booster every 5-10 years
What is the risk/benefit ratio?
- -Vaccine producer: to try to make vaccine as free of side effects as possible
- -Society understand risk/benefit to make informed decision
- -Health professional: To be able to explain the potential benefit vs risk to society
What is meningitis?
- -Inflammation of the protective membranes covering the CNS, known collectively as the meninges.
- -layers: Dura, Arachnoid, and Pia mater
What is the difference between viral and bacteria meningitis?
- -They both infect the skin, urinary system, GI, respiratory tract can be spread by the bloodstream to the meninges through CSF.
- -Most cases of meningitis ( both) result from infection that are contagious, spread via tiny drops of fluid from the throat and nose of someone who is infected. Drops may be airborne.
- -Bacterial meningitis is rare but serious can be life-threatening if it is not treated right away
- -Viral meningitis (aseptic meningitis) is relatively common and far less serious
What is purulent meningitis?
What are common symptoms of meningitis?
- -Fever, greater than 101
- -Severe sudden headache
- -Neck/back stiffness
- -Mental changes
- -Rashes (in some cases)
- -Infants may not have these symptoms and might simply be extremely irritable, lethargic, or have a fever. May be difficult to comfort, even when they are picked up and rocked.
How do you diagnosis meningitis?
-Done by spinal puncture and extraction of CSF which is sent to the lab for a culture
What are the bacterial causes of meningitis?
- They all have capsules!
- -Strep pneumoniae- #1
- -N. meningitidis- #2
- -Haemophilus Influenzae- #3
- -Strep agalactiae (GRP B Strep) -Infants
- -E. Coli (capsule K-1)- infants
What is strep pneumoniae?
- -Leading cause of meningitis
- -Infection of middle ear (otitis media) may lead to meningitis
- -No rash
- -May lead to permanent neurological sequelae
What is E. coli and Group B Strep?
- -Leading causes of neonatal meningitis
- -Diagnosis and treatment is extremely important
- - Both have capsules
What is N. Meningitidis?
- -Gram negative, oxidase positive, aerobic, diplococci
- -Has pili for attachment
- -Has outer membrane LPS
- -Intracellular and extracellular
What is the virulence factor of N. Meningitidis?
- -Capsule, pili, LPS
- -Anti-capsular opsonic antibodies are protectives
What is the pathology of N. Meningitidis?
- -Human nasopharynx is the only known reservoir
- -Carriage rate of 10% in healthy population
- -ONLY transferred from person to person in aerosol form.
- -Upon infection it resides in mucosal membrane by attaching with its pili. It then infects deeper into the tissue until it gains access to the bloodstream where it travels to infect the meninges of the brain. -Only bacteria known to cause epidemic meningitis
- -Affects individuals aged between 3 years and adolescents
What is the Waterhouse-Friderichsen syndrome?
- -Massive usually bilateral, hemorrhage into the adrenal glands (lose it) caused by severe meningococcemia
What is the invasiveness of N. Meningitidis?
- -Infection of the nasopharynx is usually subclinical and resolves within several weeks.
- -In a few individuals it invades the circulation and causes clinical disease:
- 1. An uncomplicated bacteremic process
- 2. A systemic infection that commonly involves the meninges- 3% mortality rate
- 3. A very severe systemic infection (meningococcemia) with circulatory collapse and disseminated intravascular coagulation (DIC) with petechial rash
What are symptoms of N. Meningitidis?
- -Petechial rash
- -Necrosis and vascular collapse
What is the therapy for N. Meningitidis?
- -Penicillin is the drug of choice to treat meningococcemia and meningococcal meningitis
- -Must diagnose quickly
- -Rifampin for chemoprophylactic use for exposed individuals
How many types of N. Meningitidis are there?
- -12 types capsular LPS that cause human disease
- -Most important serogroups are A, B, C, Y, and W135
- -Serogroup B causes the most cases in USA. NO vaccine too similar to own tissue
What is the prevention of N. Meningitidis?
- -There are two vaccines available in the US
- -Meningococcal polysaccharide vaccine (MPSV4) Older adults
- -Meningococcal conjugate vaccine for kids under 4. At routine preadolescent visit
- -Vaccines can prevent all but B
- - If never received vaccine, get in high school and before college freshmen in dorms and military recruits
What is Haemophilus influenzae?
- -Gram negative, pleomorphic rods
- -Grows in chocolate agar which contains NAD and Heme (lysed RBC).
- -Use to be #1 in peds
What is the pathology of Haemophilus Influenza?
- -Lives in the human respiratory tract of up to 90% of all healthy individuals. Most strains are opportunistic pathogens
- -Encapsulated are the pathogenic ones
- -Capsule type B (HiB0 is the most pathogenic one
- -Unencapsulated H. Influenzae (non-b type) causes ear (otitis media) and eye (conjunctivitis) infections and sinusitis in children, and is associated with pneumonia
How has the HiB vaccine improved infection?
- -Until vaccine discovery, HiB was #1 cause of bacterial infection in young children
- -In infants and children (ages 2 months to 4 yrs) Hib caused a variety of diseases such as meningitis, epiglottis, speticemia, pneumonia, and arthritis
- -Due to vaccine, Hib has dcreased to 1.3/100,000 children
What is the therapy of HiB?
- -High mortality if not treated
- -Treat with IV 3rd generation cephalosporin
- -Causes post-infection neurological sequelae
What is the prevention of Hib?
- -PRP vaccine: Mounts a T-independent response, no memory, not appropriate for infants, helpful for older children and adults
- -Conjugate- for kids, carb capsule conjugated to a protein (diphtheria toxoid) to make it more immunogenic
- -Very effectiveness
- -Schedule: 2, 4,6 months, 12-15 months, 16 months to 4 years
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