microbio chapter 20

anxenic environment

what kind of environment is the CNS

• it has no normal microbiota

blood brain

inflammation affects _____ barrier permeability allowing pathogens to access CNS

Breaks

__ in the bones and meninges, allows pathogens to access CNS

____ procedures allows pathogens to access CNS

peripheral neurons

pathogens travel in ___ to the CNS

toxins

one of the ways that bacteria cause disease

• bacteria growing elsewhere releases ___ that affect neurons

  • Botulism

  • tetanus

Nervous system

one of the ways that bacteria cause disease

• infect cells of the ____

  • meningitis

  • leprosy

Bacterial meningitis

• sudden high fever, severe meningeal inflammation adn increases white blood cells in the CSF

• inflammation causes the most signs and symptoms

• infection of the brain causes encephalitis

  • can result in behavioral changes, come, and death

• can develop rapidly

• other species are transmitted via respiratory droplets

90

five species cause ___ % of bacterial meningitis cases

• nesseria meningitidis

• streptococcus pneumoniae

• haemophilus influenzae

• listeria monocytogenes

• streptococcus agalactiae

opportunistic members of normal microbiota can also cause meningitis

neisseria meningitidis

• gram negative cocci

• known as meningococcus

• blebbing releases lipid A into the body

  • triggers fever, inflammation, shock, clotting

• frimbriae, capsule, and lipoligosaccaride help the bacteria attach to cells

  • neisseria cells without these structures are avirulent

  • capsule protects bacteria from phagocytic lysis

• most prevalent

streptococcus pneumoniae

• gram positice coccus

• leading cause of meningitis in adults

• capsule protects bacteria from digestion by phagocytes

• enzymes and toxins enable bacteria to counteract immune defenses

• phosphorylcholine triggers endocytosis by cells

• most prevalent

haemophilus influenza

• pleomorphic bacillus

• obligate parasite of humans and some other anials

• capsule resistes phagocytosis

• different ___ strains distingusich by capsular antigens

• prior to vaccination, most disease caused by ____ type b

• leading cause of bactieral meningitits prior to vaccination

listeria monocytogenes

• gram positive coccobacillus

• enters the body in contaminated food or drink

• rarely pathogenic in healthy adults

• meningitis occur in pregnant women, fetuses, newborns, and the elderly or immunocompromised

• production of listeriolysin O protects the bacteria from phagocytic digestion

streptococcus agalactiae

• lancefield group B streptococcus

• normal vaginal microbiota in some women

• capsule allows bacteria to evade phagocytosis

• causes bacteremia, pneumonia, and meningitis in newborns

• leading cause of meningitis in newborns

birth

when is S. agalactiae aquired

contaminated food

what is listeria transmitted

blood

how does bacteria spread to get to the meninges

head or neck

what kind of trauma may allow entry of bacteria into the meninges

mother to fetus

the only way that listeria can be transmitten through humans

meningococcal meningitis

can be come epidemic

IV antimicrobial drugs

how is bacterial meningitis treated

vaccines

what are available for S. pneumoniae, H. influenzae type b, and N. meningitidis

penicillin

administration of what at birth reduces noonatal meningitis due to S. agalactiae

listeriosis

individuals at risk for __ should avaoid high risk foods

Hansens disease

• death is rare

• two types

• lepromatous

  • more virulent form of the disease

  • weak cell mediated immune response

• tuberculoid

  • non-progressice form of the disease

  • strong cell-mediated immune response

• Transmitted person to person contact or breaks in the skin

• treatment may be life long

tuberculoid leprosy

• non-progressive form of leprosy

• strong cell-mediated immune response

lepromatous leprosy

• more virulent form of the leprosy disease

• weal cell-mediated immune response

• becoming rare

mycobacterium leprae

what is the pathogen for leprosy

• gram positive bacillus

• grows best in cooler regions of the body

• can live inside infected cells for years

• cellular immune response eventually attacks infected cells

  • may destroy nerves and other tissues

myolic acid

in mycobacterium leprae the ___ in the cell wall is responsible for several characteristics of the bacterium

• slow growth rate

• protection from phagocytic lysis

• growth within phagocytes

• resistance to many antimicrobial drugs

acid-fast bacilli

the diagnosis of leprosy is confirmed by presence of what in samples

BCG

what vaccines provides protection from leprosy

botulism

• three manifestations

  • foodborne

  • infant —

  • wound —

• about 60 cases of foodborne adn wound per year in US

• infant — most common form in US

• symptoms are diagnositc

honey

infants under 1 should not consume what to avoid botulism

endospores

what should be destroyed in contaminated food to prevent botulism

botulism treatments

• maintain open and functional airways

• wash intestinal tract to remove clostridium

• administer __ immune globuln

• treat with antimicrobial drugs

clostridium botulinum

pathogen for botulism

• gram positive, endospore forming bacillus

• common worldwide in soil and water

• different strains produce one of seven neurotoxins

foodborne botulism

• progressive paralysis on both sides of the body

• slow recovery from growth of new nerve cell endings

infant botulism

• results from ingestion of endospores

• non-specific symptoms

wound botulism

• contamination of a wound by endospores

• symptoms are similar to those of foodborne —-

tetanus

• tightening of the jaw

• spasms and contractions may spread to other muscles

• irregular heartbeat and blood pressure; profuse sweating may occur

• vaccine is available

• diagnosed by on characteristic muscle contraction

• morality rate is about 50 if left untreated

• incidence has decreased worldwide

• most cases occur where immunization or adequte medical care is unavailable

clostridium tetani

• pathogen for tetanus

• produces neurotoxin tetanospasmin

• found in soil, dust, and intestines of humans and other animals

• can acquire through break in skin or mucous membranes

• distance of infection from CNS determines incubation period

tetanus treatment

• through wound cleaning

• passive immunotherapy

• administration of antimicrobials

• active immunization

viral diseases of nervous system

• viruses more readily cross the blood-brain barrier

• occure more frequently than bacterial and fungal infections

• include meningitis, polio, rabies, and encephalitis

viral meningitis

• signs and symptoms similar to those of bacterial meningitis

• usually milder and more common than those of bacterial or fungal meningitis

• spread via respiratory droplets and feces

• diagnosed by characteristic signs adn sumptons adn absence of bacteria in CSF

• no treatment exists

• difficult to prevent spread of enteroviruses

fecal contamination of food, water, or hands

how are the pathogens that cause viral meningitis spread

bloodstream to other organs following ingestion

how is viral meningitis pathogens spread in the body

RNA

viral meningitis

90 % of cases causes by ___ viruses in the genus enterovirus

• Coxsackie A virus, coxsackie B virus, echovirus

damage to cells in the meninges triggers menintitis

Poliomyelitis

• epidemics of — were common in the past

• may become second human disease to be eradicated

• signs and symptoms

  • asymotomatic infectons: almost 90 percents of case

  • minor —: non-specific symptoms

  • non-paralytic —: muslce spasms and back pain

  • paralytic —: produces paralysis

  • post— syndrome can be debilitatiing

• currently exists in a few countrues in africa and asia

• diffcult to control in these regions because of several factos

  • poor sanitation

  • high population density

  • political and religious tensions

poliovirus

pathogen that casues poliomyelitis

transmitten most often by drinking contaminate water

throat or feces

diagnosed through identification of pathogen in throat or feces

no specific treatment exists

two

how many effective vaccines are there for poliomyelitis

rabies

• characteristic neurological signs if virus reaches CNS

  • hydrophocia, seizures, hallucination, paralysis

• zoonotic disease

• diagnosis by unique neurological symptoms

• postmortem detection of negri bodies in the brains

• treated with human —- immunoglofulin, vaccine injections, and cleaning of infection

• prevented by controlling in animals

  • vaccine available for at risk individuals

rabies virus (ssRNA virus)

the pathogen that causws rabies,

• transmitted via bite or scratch from infected animal

• virus replicates in muscle cells adn then moves into neuron

arboviral encephalitis

• are arthropod-borne viruses

  • transmitted via bloodsucking arthropods

• mosquite-borne —- can cause ——

• as zoonatic disease, rarely affect humans

• signs

  • mild, coldlike symptoms

  • can cayse ___ if the blood-brain barrier is crosses

• infect many different animals

west nile virus

siz arboviruses cause most cases of viral encephalitis in americans

• — is the most significant cause in the united states

mycoses

— of the nervous system

• spread from the lungs to the CNS via blood

• mushroom toxins can produce hallucinations adn neurological problems

• may also produce fungal meningitis

cryptococcal meningitis

• signs

  • similar to those of bacterial meningitis

  • loss of vision and coma may occur in later stages

• diagnosed by detection of fungal antigen in CSF

• treated with intravenous antifungal drugs

• hospitals try to prevent entry of — contaminated air

crytococcus neoformans

pathogen for cryptococcal meningitis

• two variants of the yeast found worldwide

resists phagocytosis by defensive cells

• infections follows inhalation of spores or dried yeast cells

• occurs in terminal AIDS patients and in transplant recipients

protozoan

— diseases of the nervous system

• infections of the nervous system are rare

• two diseases caused by this

  • African sleeping sickness

  • Meningocephalitis

African sleeping sickness

• signs

  • three clinical stages

    • site of bite becomes lesion

    • parasites in the blood create fever lymph node swelling, and headache

    • protozoa invade CNS, causing meningoencephalitis

• diagnosed by microscopic observation of trypanosomes in blood, lymohm spinal fluid, or biopsy

• treatment based on stage of disease

  • must begin soon after infection to be successful

• reduce expose to vector inecticide application canhelp reduce occurence

trypanosoma brucei

the pathogen that causes african sleeping sickness

evades immune system by changing surface glycoproteins

primary amebic meningoencephalopathy

• signs

  • same as those of meningitis and encephalitis caused by other microbes

• diagnosis, treatment, prevention

  • detect amoebae in sample from eye, brain, or in CSF

  • brugs have limited success

  • prevented by avoiding contaminated water supplies

acanthamoeba and naegleria

pathogen that causes primary amebic meningoencephalopathy

enters host thoruh abrasions on the skin or the eyelid or by inhalation of contaminated water

rare, but also always fatal (nargleria)

prion disease

• spongiform encephalopathies

  • class of disease that include scrapie and “mad cow” disease

  • leaves brains of victims full of holes due to massive cell death

  • can occur spontaneously in the elderly

  • humans can contract by eating meat from infected cattle

variant crutzfeldt (jakob disease)

a prion disease

• signs

  • insomnia, weight loss, and memory failure

  • progressive worsening of muscle control

• diagnosis, treatment, prevention

  • diagnosed by characteristic signs adn symptoms, can be confused with other forms of dementia in elderly

  • no treatment is available

  • destruction of prions outside of body is difficult

trachoma

microbial disease of the eye

• signs

  • scarring of conjunctive and cornea

• leading cause of non-trumatic blindness

• diangosed by identifying bacteria at site of infection

• treated with antimicrobials

• surgery can correct eyelid deformities

chlamydia trachomatis

• pathogen that causes trachoma

  • purulent discharge causes defored eyelids

  • scarring can lead to blindmess

  • typically effects children

skin and reproductive tract

bacterial infections of the ___ and __ can affect the eyes

ophthalmia neonatorum

inflammation of the conjuctiva and cornea of a newborn

Conjunctivitis

inflammation of the conjunctiva

keratitis

inflammation of the cornea