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Nervous and Eye Diseases: Lecture 2 (Bacterial Meningitis (humans inhale N…
Nervous and Eye Diseases: Lecture 2
H. Influenzae
pleomorphic bacillus
different strains distinguished by capsular antigens
most strains have a capsule that resist phagocytosis
does not cause influenza
Listeria Monocytogenes
gram + coccobacillus found on soil, water, and animals
tolerates cold and can grow in refrigerated drinks and foods
enters in contaminated food and drink
rarely pathogenic in healthy humans
meningitis can occur in pregnant woman, fetuses, newborns, elderly, and immunocompromised ones
only mild like flu s/s
produces listeriolysin O protects bacteria from phagocytic digestion
S. Agalactiae
also called lancefield group B streptococcus due to b antigen
in normal vagina microbiota in 1/3 of women
makes protective capsule to allow bacteria to avoid phagocytosis when it gets into the blood
causes bacteremia, pneumonia, and meningitis in newborns
Bacterial Meningitis
humans inhale N. meningitidis, H. influenzae, and S. pneumoniae in respiratory droplets from a person who has it
S. agalactiae is acquired through an infected birth canal
listeria is transmitted through contaminated food
bacteria spread by blood or from infected of lungs, sinuses or inner ear to meninges.
head or neck trauma may allow entry of bacteria into meninges
S. pneumoniae and N. meningitidis are the leading causes of the disease now
S. agalactiae is the leading cause in newborns
S. pneumoniae grows on mouths and throats of 75% of humans without harm
can become an epidemic
spread to those in barraks and droms of college living together
human to human transmission is limited except from mother to fetus
can result is premature birth, miscarriage, stillbirth, or meningitis
dx: s/s are considered SERIOUS and seek medical attention, based on s/s and culturing of bacteria from CSF
Tx: intravenous antimicrobial drugs- typically Vancomycin
vaccines available for S. pneumoniae, H. influenzae, and N. meningitidis
admin. of penicillin at birth whose mothers vagina is colonized with S. agalactiae reduces neonatal meningitis
recommends meningococcal vaccination for freshman in college and military recruits
those at risk for listeriosis should avoid high risk foods
Hansons Disease
also called leprosy
s/s of tuberculoid leprosy
no progressive form of disease due to pts with a strong T cell immune system. strong cell-mediated response, regions of skin have lost sensation as a result of nerve damage
s/s of lepromatous leprosy
more virulent type, weak cell-mediated response, bacteria multiplies in skin and mucous membranes, and nerve cells, destroys tissues and leads to progressive loss facial features, digits, and other structures
s/s come slowlu and could take years
death is rare
pathogen: mycobacterium leprae; gram + bacillus with a cell wall that contains mycolic acid which is responsible for several characteristics of bacterium
bacterium has never grown in a cell free lab culture
nine branded armadillo is the only other natural host
M. leprae grows best in colder regions of the body
reproduces in neuroglia of peripheral nerves and can live in infected cells fro 10-30 years with no s/s
cellular immunity eventually attacks infected cells
transmitted from person to person contact or breaks in the skin; contact with infected person for years
dx: based on s/s of loss of sensation in skin lesions and disfiguration; confirmed by presence of acid-fast bacilli (AFB) or acid-fast rods (AFR) in samples
tx: with multiple antimicrobials; can be lifelong for some pts
BCG- the tuberculosis vaccine can provide some protection
prevent by avoiding exposure to the pathogen