Lecture 12 Flashcards
What are the general characteristics of Neisseria?
Gram– dipplococci; small nonmotile aerobes that are oxidase-positive, has pili; invasive
What is the reservoir for Neisseria?
STRICTLY human
What exotoxins do Neisseria species produce?
no exotoxins have been identified
What disease do Neisseria species cause commonly?
Gonorrhea
What is the second most common bacterial STI in USA?
Gonorrhea
What is the most (#1) common STI in USA?
HPV
What is the difference between a disease and infection?
one can have an infection without developing a disease
Why is using the term “STI” more accurate than using the term “STD”? (infection vs disease)
one can be infected but not form a disease and have no symptoms = asymptomatic but can pass on infection to another person who may develop symptoms = disease
Who first identified Neisseria species? What year?
Albert Neisser (German physician), 1879
What is another name for the Neisseria species?
Moraxella species
What are the 2 Neisseria species discussed?
N. gonorrheae and N. meningitides
What is another name for N. gonorrheae?
Gonococcus
What is another name for N. meningitides?
Meningococcus
What diseases does Gonococcus cause?
Gonorrhea
What diseases does Meningococcus cause?
bacterial meningitis and septicemia
How many known Neisseria/Moraxella species are found in humans?
10
What is gonorrhea (STI) called in the hood?
The Clap
What kind of pathogen is N. gonorrheae considered to be and why?
mucosal pathogen because it colonizes with mucosal epithelial membranes/surfaces
What are the 2 characteristics of all mucosal pathogens?
cannot survive outside of host and highly sensitive to light
What is the mode of transmission of N. gonorrheae?
vaginal/anal/oral sex (due to genital secretions) with someone infected (does not need to have the disease)
Is gonorrhea a new or old disease? What is the evidence?
old bacteria STI infected men from ancient world as well as Biblical references
What does “gono” and “rrhea” mean?
“gono” = seed and “rrhea” = flow
What does “asymptomatic carriage” mean?
pathogen is carried mostly via asymptomatic persons
What percentage of women are asymptomatic?
~20-40%
What percentage of men are asymptomatic?
~10%
Which gender is more susceptible to develop gonorrhea and why?
men because they are only 10% asymptomatic
Which gender is more likely to transmit gonorrhea and why?
women because they are more asymptomatic = will not know IF they are infected
What are the common symptoms of gonorrhea in women?
vaginitis (mild), increased vaginal discharge, vaginal bleeding between periods
In which gender does painful/burning sensation when urinating occur as a symptom of gonorrhea? What is this due to?
BOTH men and women; due to infection of urethral canal
What are the common symptoms of gonorrhea in men?
penile discharge (white, yellow, or green), painful/swollen testicles (less common)
What are the symptoms of gonorrhea in a rectal infection?
P-DABS = Painful bowel-movements, Discharge, Anal-itches, Bleeding, Soreness
Can symptoms of gonorrhea occur anywhere else in the body other than the reproductive tract?
Yes, like in the liver and pharynx
What is gonococcal conjunctivitis?
N. gonorrheae causes an eye infection in newborns from their infected mothers
How does gonococcal conjunctivitis occur?
women infected with N. gonorrheae (asymptomatic or not) pass the pathogen to the newborn via delivery thus affects eyes of the newborn
How can gonococcal conjunctivitis be prevented?
via prophylactic treatment where drops of erythromycin are applied onto all newborn’s eyes to prevent infection in case if the mother is infected
How many new cases/year of gonorrhea in the US? Is this an estimation or exact? Who does it include?
~700,000 = estimation as it includes reported cases and unreported asymptomatic cases of infected individuals
What are 3 reasons for the many cases of gonorrhea?
1) acquired immunity doesn’t exist = can get reinfected | 2) use of oral contraceptives = help bacteria colonize | 3) symptoms in females may be mild = undetect disease = pass to sexual partners
Between bacterial STIs and viral STIs, which is more treatable and why?
bacterial STIs = antibiotics available; antibiotics cannot treat viral STIs
What is the 3rd most common STI in US?
syphillus
How can one bring a rare STI to the US?
when one travels out of the country and has unprotected sex
Which region of the world has the highest cases of gonorrhea?
Africa
Which part of the US has the highest occurrence of gonorrhea?
south-east USA
Which ethnic group in the US does gonorrhea highly occur in?
African-Americans
What is the reason for the decline in gonorrheal cases (US) during 1945-1955?
war and production of antibiotics
What is the reason for the increase in gonorrheal cases in the US during the 1960s?
sexual revolution #hippienation
What is the reason for the decline in gonorrheal cases in the US from 1981?
increase awareness of STIs due to increase awareness of AIDS and HIV = more people started practicing safe sex
What are the 5 virulence factors of N. gonorrheae?
pili, Opa surface proteins, IgA1 autotransporter, Lipo-oligosaccharide and peptidoglycan endotoxins
What is the function of the pili in pathogenesis?
bind to surfaces
What is the function of the Opa in pathogenesis?
bind to mucosal epithelial and phagocytic cells ; cell-cell signaling
What is the function of the IgA1 autotransporter in pathogenesis?
acts as a protease cleaving IgA1 antibodies
What is significant about the mechanism of the IgA1 autotransporter of N. gonorrheae?
these bacteria have been “born” to fight the host immune system at mucosal surfaces by releasing the IgA1 protease = will degrade and inactivate the IgA1 antibodies | makes sense because gonorrhea=old disease=N. gonorrhea knows how to attach mucosal epithelial cells
Where are IgA1 antibodies found?
on mucosal surfaces
What is the difference in the mode of invasion between Gonococcus and Meningococcus?
Gonococcus = no capsule = infection remains localized only to mucosal epithelial surfaces | Meningococcus = has capsule = infection not localized = can enter bloodstream and infect other organs
What is antigenic variation and how does it occur?
changes in the composition/structure of “main” surface molecules on bacteria’s cell surface = allows them to avoid recognition by specific antibodies during the course of an infection | happens via random genetic rearrangements (change sequence = change structure)
What structure on N. gonorrheae undergoes antigenic variation?
the pili
What is the consequence of the antigenic variation mechanism of N. gonorrhea on us the hosts?
contributes to the lack of protective immunity during infection because the immune system never recognizes the bacteria, its always under some disguise = why people can be reinfected
What are the 2 mechanisms N. gonorrhea uses to escape detection by the immune system?
antigenic variation and phase variation
What is phase variation?
genes that encode for the specific outer-membrane proteins contain repeats | change the number of repeats = change sequence = change structure
What structure on N. gonorrheae undergoes phase variation?
the Opa proteins
What are the 4 methods of diagnosis to detect/identify presence of N. gonorrheae?
1) swab of discharge from infected area | 2) microscopy-Gram stain | 3) culture on selective media, biochemical assays | 4) PCR (4hrs, sensitive/specific)
What was the first antibiotic used to treat gonorrhea and why is it no longer recommended for treatment?
penicillin, many penicillin-resistant strains
What are 2 examples of antibiotics used for treatment?
quinolones and cephalosporins (= QuinoCephs)
What is a rising problem in the treatment of gonorrhea, what is N. gonorrheae then considered as?
multi-drug-resistant strains on the rise - considers N. gonorrheae to be a Super Bug :(
Are there vaccines available to prevent N. gonorrheae infections? Explain.
No vaccines available due to: changes (hyper-variablility) of surface proteins | blocking antiboies like the IgA1 autotransporter | N. gonorrheae spends most of time inside host = intracellular resistance (evolved to fight off host defenses)
What is the reservoir for N. meningitides?
human
What is the mode of transmission for N. meningitides?
direct contact and airborne; asymptomatic carriage also possible
What are the 5 most common serogroups of N. meningitides?
A, B, C, W-135, Y
What is bacteremia?
BACTERIA in the blood
What is septicemia?
INFECTION in the blood
What does the type of infection of N. meningitides that we have refer to?
infection of the membrane that surround the brain
What are the 2 stages of bacterial meningitis?
1) bacteria enters blood and colonizes meninges | 2) inflamed meninges allows phagocytes and blood proteins to enter spinal fluid and brain
What is the sequence of events of bacterial meningitis?
bacteria enters host via respiratory system »_space; it crosses mucosal epithelial cells »_space; enters bloodstream »_space; lands on central nervous system, colonizes membranes of CNS and brain
What causes the inflammation of the meninges?
the infection, colonization of the meninges
What is responsible for most of the damage and why?
the inflammation causes/allows blood proteins and phagocytes to enter the spinal fluid and brain
What are the initial symptoms of bacterial meningitis?
fever, rash, stiff neck, headache (= FRSH)
What percent of cases lead to death and what is significant about this?
3% and includes individuals that have been treated with antibiotics
What are the virulence factors of N. meningitides?
capsule and LOS endotoxin
What specimen is collected for diagnosis?
blood
What are the methods to diagnose/detect the presence of N. meningitides?
culture, microscopy, PCR-based assay
What antibiotics are used to treat bacterial meningitis?
cephalosporins & penicillin (CephaPen)
How many vaccines are available to help prevent infection due to N. meningitides?
4
What are the vaccines that contain the capsular polysaccharide serogroups?
Meningococcal ACWY vaccine (A, C, W-135, Y serogroups included) and Meningococcal B vaccine
Which vaccine is ineffective on infants and why?
Meningococcal ACWY vaccine because it does not contain the B serogroup
