chapter 17 Flashcards
17.1 The Nervous System and Its Defenses
two components:
CNS - brain and spinal cord
PNS - nerves that come from brain and spinal cord ang disperse into (think nerves going into peripherals)
three important functions of the NS
sensory, integrative, and motor
sensory function of NS
sensory function is fulfilled by sensory receptors at the end of peripheral nerves; they generate nerve impulses that are transmitted to the CNS where they are translated or integrated into sensation or thought which = motor function
cells that make up tissues of the brain and spinal cord that receive and transmit signals to and from the PNS and CNS; make up the ______ and _________
nerves;
brain and spinal cord
soft tissue of the brain and spinal cord is encases within a tough casing of three membranes called the _________; tri layer membrane covering the brain and spinal cord
meninges
consists of the dura mater, arachnoid mater, and pia mater (going outermost to innermost)
meninges
what is in the subarachnoid space?
: subarachnoid space is the space between the arachnoid mater and pia mater
filled with a clear serumlike fluid called cerebrospinal fluid
function of CSF
provides nutrition to CNS and provides a liquid cushion for the sensitive brain and spinal cord
the meninges are a common:
site of infection; ie. meningitis
—> microorganisms can be found in CSF during meningitis, which is supposed to be sterile
bacteria that often cause meningitis
Neisseria meningitidis (the meningococcus) Haemophilus influenzae
swelling in the nerve where the cell bodies of the neuron aggregate; part of PNS
ganglion
PNS consists of _________ and _________
nerves and ganglion
bundles of neuronal axons that receive and transmit nerve signals
nerves
what communicate in the synapse?
the axons and dendrites of adjacent neurons communicate in the synapse
chemicals called ______ are released from one cell and act on the other cell in the synapse
neurotransmitters
the defenses of the NS are mainly ________
structural
list some defenses in the NS
- bony casings of the brain and spinal cord protect from traumatic injury
- cushion of CSF
- vascular system: vessels that serve NS in brain have special permeability creating the BLOOD-BRAIN BARRIER, which allows few molecules to pass through and prohibits more microbes from passing into the CNS
- –> drawback is that drugs and antibiotics are difficult to introduce into CNS
along with the uterus and eyes, the CNS is considered an _____________ ___________ site.
immunologically privileged site, meaning these sites are only able to mount partial or at least a different immune response when exposed to immunologic challenge
the functions of the CNS are so vital for life of organisms that even temporary damage that could potentially result from “normal” immune responses could be __________
detrimental
microglia and brain macrophages
microglia: specialized cells in the CNS; cell with phagocytic capabilities
brain macrophages: phagocytic
—> activity of both of these cells is thought to be less than that of phagocytic ells elsewhere in the body
17.2 Normal Biota of the NS
it is still believed there is no normal biota in either the CNS or PNS
–> finding microbes of any type in these tissues represents a deviation from the healthy state
viruses such as _______-_______ live in a dormant state in the NS between episodes of acute disease, but are not considered _________ _______
herpes simplex
normal biota
there is a lot of research suggesting that the ___ microbiome influences the NS in many ways, in fact: the development of the brain, blood brain barrier, and proper construction of peripheral nerves are influenced by the microbiome in the developing ______
gut
gut
17.3 NS Diseases Caused by Microorganisms
Meningitis (inflammation of the meninges) treatment and diagnosis
when meningitis is suspected: lumbar puncture (spinal tap) is performed to obtain CSF, which is then examined by gram stain and/or culture
—> tx often begins with broad-spectrum antibiotics
most serious forms of acute meningitis are caused by _________, but it is though that their entrance to the CNS is often facilitated by coinfection or previous infection with ___________ _________
- bacteria
2. respiratory viruses
meningitis s and s
no matter the cause the typical sx are:
- severe headache
- painful or stiff neck
- fever
- nausea and vomiting
- photophobia (sensitivity to light) may also be noted
- skin rashes in specific types of meningitis
- usually increased WBCs in CSF
-can be acute or chronic, depends on infectious agent
Meningitis: Neisseria meningitidis (G-)
“meningococcus”
Hint: often associated with epidemic forms b/c of endotoxins which cause rapid decline marked by petechiae and HIGH FEVER, but can be helped with ceftriaxone and cefotaxime; IgA PROTEASE
Trans: droplet contact (reservoir: humans who harbor patho in nasopharynx)
V Factors: capsule, endotoxin, IgA protease
Culture/dx: Gram stain/culture of CSF, rapid antigenic tests, oxidase tests (test CSF, blood, or nasopharyngeal samples); cultivation is preferred method of dx on Modified Thayer-Martin or chocolate agar medium
Prevention: conjugated vaccine; ciprofloxacin, rifampin, or ceftriaxone used to protect contacts
Tx: Penicillin, ceftriaxone, cefotaxime
Distinct Feats: Petechiae(damage to blood vessels by cytokines) on trunk and appendages, meningococcemia (bacteria enter blood), RAPID DECLINE, sudden onset marked by HIGH fever, sore throat, chills, delirium, bleeding in the skin, shock, and coma
Epidemiological Feats:
US 2018: 329 cases
Meningitis “belt” in Africa: 1000 cases per 100,000 annually
Serotypes B, C and Y are responsible for more cases of infection
Highest risk pop: young children, 6-36 months old (3 y/o)
and young adults (10-20 y/o)
Meningitis: Streptococcus pneumoniae (G+) “pneumococcus”
Hint: causes the majority of bacterial pneumonias, and causes meningitis; most frequent cause of community-acquired meningitis
Trans: droplet contact
V Factors: capsule that protects from phagocytosis, brain cell apoptosis, hemolysin and hydrogen peroxide production
Culture/dx: Gram Stain/culture of CSF
Prevention: Two vaccines: PCV13 (Prevnar) and PPSV23 (Pneumovax 23)
Tx: Penicillin, vanco + ceftriaxone; in SERIOUS THREAT cat. in antibiotic resist.
Distinct Feats: serious, acute, MOST COMMON meningitis in adults
Epidemiological Feats:
US incidence before vaccine for children: 7.7 hospitalizations per 100,000 —> after vaccine for children: 2.6 per 100,000
Meningitis: Haemophilus influenzae (G-)
Trans: droplet contact
V Factors: capsule
Culture/dx: culture on chocolate agar
Prevention: Hib (H. influenzae serotype b) vaccine, ciprofloxacin, rifampin, or ceftriaxone
Tx: Ceftriaxone
Distinct Feats: serious, acute, less common in US since vaccine became available; SEVERE
Epidemiological Feats:
Before ***Hib vaccine, 300,000-400,000 deaths worldwide per year
Meningitis: Listeria monocytogenes (G+)
Hint: think Listeria= Listerine which goes in mouth like food, everyone eats food (adults, neonates, elderly, immunocompromised), and everyone can die from choking: range of shapes of bacteria -> think shaped noodles, and think food has different temps and pH needs just like Listeria (not fastidious)
Trans: Vehicle (food) -> most cases but the primary reservoir is water/soil
V Factors: intracellular growth
Culture/dx: cold enrichment, rapid methods ELISA/immunofluorescence/gene probe
Prevention: cooking food, avoiding unpasteurized dairy products
Tx: Ampicillin, trimethoprim-sulfamethoxazole, gentamicin
Distinct Feats: asymptomatic in healthy adults; meningitis in neonates, elderly, pregnant, and immunocompromised -> can result in septicemia
Epidemiological Feats: mortality can be as high as 33%
Meningitis: Cryptococcus neoformans (Fungus)
HINT: think AIDS patients were thought of as FUNGUS right from NEOnate stage, and required lots of TESTING
Trans: vehicle (air, dust)
V Factors: capsule, melanin production
Culture/dx: negative staining, biochemical tests, DNA probes, cryptococcal antigen test
Prevention: no prevention
Tx: Amphotericin B and fluconazole
Distinct Feats: acute or chronic, most common in AIDS patients and is frequently fatal
Epidemiological Feats:
- in US, mainly a concern for HIV+ patients; 90% drop in incidence in the 1990s due to better management of AIDS
- worldwide 1 million new cases per year
most common sx: headache, nausea, neck stiffness
Meningitis: Coccidioides immitis (Fungus)
Hint: Coccidioides causes cocci (spherule) shaped granulomas on Sabouraud’s agar in endemic regions
Trans: vehicle (air, dust, soil)
V Factors: Granulomas (spherule) formation
Culture/dx: identification of spherules, cultivation on Sabouraud’s agar; arthroconidia (arthrospores) grow at incubation of 37-40degrees and develop into spherules in the lungs
Prevention: avoiding airborne endospores
Tx: Fluconazole or Amphotericin
Distinct Feats: almost exclusively in endemic regions, causes Valley Fever
Epidemiological Feats: incidence increasing in recent years
Meningitis: Viruses “aseptic meningitis”
Hint: viral meningitis is ruled out by searching for bacteria, fungi, and protozoa, and then performing antigen tests —> lucky because milder than B or F, BUT is lytic to cells :(
Trans: droplet
V Factors: lytic infection of host cells
Culture/dx: initially, absence of bacteria, fungi, and protozoa, followed by antigen tests
Prevention: no prevention
Tx: usually none (unless specific virus identified and specific antiviral exists)
Distinct Feats: generally milder than bacterial or fungal forms; 90% caused by enteroviruses
Epidemiological Feats:
In US, 4 of 5 meningitis cases are caused by viruses: 26,000-42,000 hospitalizations per year
Neonatal Meningitis
Trans: almost always a result of infection transmitted by the mother in utero or during passage through birth canal
Neonatal Meningitis: Streptococcus agalactiae (G+) group B
Trans: vertical (during birth)
V Factors: capsule
Culture/dx: culture mother’s genital tract on blood agar; CSF culture of neonate
Prevention: culture and treatment of mother between 35 and 37 weeks gest.
Tx: Ampicillin and penicillin G (PENICILLIN IS DRUG OF CHOICE)
Distinct Feats: MOST COMMON; positive culture of mother confirms diagnosis
Epidemiological Feats:
Before intrapartum antibiotics intro’d in 1996: 1.8 cases per 1000 live births
After intrapartum antibiotics: 0l32 cases per 1000 live births
Neonatal Meningitis: Escherichia coli, strain K1 (G-)
Trans: vertical during birth
V Factors: none
Culture/dx: CSF gram stain/culture
Prevention: no prevention
Tx: Ceftazidime or cefepime +/- gentamicin
Distinct Feats: suspected if infant is premature; second most common cause
Epidemiological Feats: estimated as 0.2-5 per 1000 live births; 20% of pregnant women colonized; poor prognosis
Neonatal Meningitis: Listeria monocytogenes (G+)
Trans: vertical
V Factors: intracellular growth
Culture/dx: cold enrichment, rapid methods (ELISA)
Prevention: cooking food, avoiding unpasteurized dairy products
Tx: ampicillin, trimethoprim-sulfamethoxazole
Distinct Feats: none
Epidemiological Feats: mortality can be as high 33%
Neonatal Meningitis: Cronobacter sakazakii
Trans: vertical (baby formula)
V Factors: ability to survive dry conditions
Culture/dx: chromogenic differential agar, or rapid detection kits
Prevention: safe preparation of formula, avoidance of powdered formula
Tx: begin with broad spectrum drugs until susceptibilities determined
Distinct Feats: none
Epidemiological Feats: rare (a handful of documented cases in US annually), but DEADLY (mortality rates as high as 40%)
Zika Virus Disease (RNA virus that is closely r/t viruses causing dengue fever, West Nile fever, and yellow fever)
-starting in 2015 and into 2016 but known since mid-1990’s, in Brazil babies were being born with microencephaly, determined to be Zika virus
Trans: vertical, vector-borne (Aedes mosquito), sexual contact, likely through blood transfusions
V Factors: none
Culture/dx: PCR testing
Prevention: avoiding mosquitos, unprotected sex with infected; vaccines in trial
Tx: supportive measures
S/S:
Adults: skin rash, conjunctivitis, muscle/joint pain, can trigger Guillain-Barre syndrome (immune system attacking peripheral nerves)
Babies: microencephaly, vision problems, seizures, involuntary movements, irritability, swallowing dysfunction
Epidemiological Feats: originated in Africa but spreading throughout world; latest outbreak, leading to many microencephalies, started in 2015
Poliomyelitis (Poliovirus) RNA virus (naked capsid with chemical stability and resistance to acid, bile, and detergents)
-acute enteroviral infection of the spinal cord that can cause neuromuscular paralysis (formerly known as infantile paralysis)
Trans: fecal-oral, vehicle
V Factors: attachment mechanisms (adsorption to receptors of mucosal cells in oropharynx and intestine)
Culture/dx: viral culture, serology
Prevention: live attenuated (OPV) (developing world) or inactivated vaccine (IPV) (developed world)
Tx: none, supportive, palliative
S/S: most infections are contained as short-term, mild viremias; some develop nonspecific sx of fever, headache, nausea, sore throat, and myalgia; if viremia persists, viruses can be carried to the CNS through its blood supply
- –> infiltrates the motor neurons of the anterior horn of the spinal cord, or it can attack spinal ganglia, cranial nerves, and motor nuclei
- in paralytic disease, invasion of motor neurons causes various degrees of flaccid paralysis
Epidemiological Feats:
Eradicated from Western Hemisphere; still endemic in Pakistan and Afghanistan as of 2020. Vaccine strains caused 196 cases of paralytic polio in Africa. :(
Poliovirus is ________, meaning it attacks the nervous system
neurotropic
Bulbar poliomyelitis
rare; the brain stem, medulla, or even cranial nerves are affected
- –> this situation leads to loss of cardiorespiratory regulatory centers, requiring mechanical respirators
- –> unused muscles leads toa atrophy, growth is slowed, and severe deformities of the trunk and limbs develop (spine, shoulder, hips, knees, feet)
Post-polio Syndrome (PPS)
diagnosed in long-term survivor of childhood infection; manifests as a progressive muscle deterioration that develops in 25-50% of patients
Meningoencephalitis: Primary Amoebic Meningoencephalitis (PAM)
Naegleria fowleri (P)
Trans: vehicle (exposure while swimming in water)
V Factors: Invasiveness
Culture/dx: examination of CSF; brain imaging, biopsy
Prevention: limit warm freshwater or untreated tap water entering nasal passages
Tx: Amphotericin B; mostly ineffective
S/S: rapid, massive destruction of brain and spinal tissue after amoeba migrates into brain from olfactory nerve; hemorrhage, coma. and invariably death
Epidemiological Feats: US: 0.7 cases annually; 97% case-fatality rate
Spreading to northern states as climate warms
Meningoencephalitis: Granulomatous Amoebic Meningoencephalitis
Acanthamoeba (P)
Trans: direct contact and invades broken skin, the conjunctiva, and occasionally the lungs and urogenital tracts
V Factors: invasiveness
Culture/dx: examination of CSF; brain imaging, biopsy
Prevention: no prevention
Tx: surgical excision of granulomas; ketoconazole may help
Epidemiological Feats: predominantly occurs in immunocompromised patients
Encephalitis
inflammation of the brain
subacute meaning
indicates an intermediate status between acute and chronic disease
Acute Encephalitis: Arboviruses
(West Nile virus, La Crosse virus, Jamestown virus, St. Louis encephalitis virus, Powassan virus, Eastern Equine encephalitis virus)
Trans: vector (arthropod bites)
C Factors: attachment fusion, invasion capabilities
Culture/dx: history, rapid serological tests, nucleic acid amplification tests
Prevention: insect control
Treatment: none; support measures to control seizures, fever, convulsions, etc.
S/S: extremely variable; can include coma, convulsions, paralysis, tremor, loss of coordination, memory deficits, changes in speech and personality, and heart disorders
Distinct Feat: history of exposure to insect important
Epidemiology Feat: 20% increase in incidence 2014-2018; young children and elderly most sensitive to injury by arboviral encephalitis
Acute Encephalitis: Herpes simplex 1 or 2
Trans: vertical or reactivation of latent infection
V Factors: none (latency?)
Culture/dx: clinical presentation, PCR, Ab tests, growth of virus in cell culture
Prevention: maternal screening for HSV
Tx: acyclovir
Distinct Feat: in infants, disseminated disease present; rare between ages 30 and 50
Epidemiology Feat: HSV-1 more common cause of encephalitis; 2 cases per million per year; can cause in newborns born to HSV-positive mothers
Acute Encephalitis: JC virus
Trans: ? ubiquitous
V Factors: none
Culture/dx: PCR of cerebrospinal fluid
Prevention: none
Tx: Zidovudine or other antivirals
Distinct Feat: in severely immunocompromised, especially AIDS
Epidemiology Feat: affects 5% of adults with untreated AIDS; often asymptomatic
arboviruses
arthropod-borne viruses
- feed on blood of hosts
- infections show peak incidence when the arthropod is actively feeding and reproducing, usually from LATE SPRING through EARLY FALL
S/S of acute encephalitis
vary, but may include behavior changes or confusion b/c of inflammation; decreased consciousness and seizures frequently occur
—> sx of meningitis are often also present
JC Acute Encephalitis can cause a condition called _____________
progressive multifocal leukoencephalopathy (PML)
- uncommon, fatal complication of infection with JC virus (polyoma virus)
- -> result of virus attack on accessory brain cells
Subacute Encephalitis
when encephalitis sx take longer to show up, and when the sx are less striking, the condition is termed subacute encephalitis
- –> most common cause is a protozoan called Toxoplasma
- –> can be caused by persistent measles virus as many as 7 to 15 years after the initial infection
- –> prions can cause spongiform encephalopathy
Subacute Encephalopathy: Toxoplasma gondii (P)
Trans: vehicle (meat), or fecal-oral
V Factors: intracellular growth
Culture/dx: serological detection of IgM
Prevention: personal hygiene, food hygiene
Tx: Pyrimethamine and/or leucovorin and/or sulfadiazine
S/S: most cases are asymptomatic or marked by mild sx like sore throat, lymph node enlargement and low grade fever
Distinct Feat: subacute, slower development of disease; infection in fetus, immunodeficient people is severe and often fatal
Epidemiology Feat:
- 15%-29% of US pop. is seropositive
- internationally seroprevalence is up to 90%
- disease occurs in 3-15% of AIDS patients
- designated a “neglected parasitic infection” in the US by CDC
Interesting Fact: people with hx of Toxoplasma infection are often more likely to display thrill-seeking behaviors and seem to have slower reaction times (researchers are looking into possible association between schizophrenia and hx of Toxoplasma infection)
Subacute Encephalopathy: Subacute sclerosing panencephalitis
Trans: persistence of measles virus
V Factors: cell fusion, evasion of immune system
Culture/dx: EEGs, MRI, serology (Ab versus measles virus)
Prevention: none
Tx: none
Distinct Feat: history of measles; infection sx occur years after an initial measles episode
Epidemiology Feat: occurs in 1 in 609 persons who had measles
Subacute Encephalitis: Prions
Trans: CJD = direct/parenteral contact with infected tissue, or inherited vCJD = vehicle (meat, parenteral)
V Factors: avoidance of host immune response
Culture/dx: biopsy, image of brain
Prevention: avoiding infected meat or instruments; no prevention for inherited form
Tx: none
Distinct Feats: long incubation period; fast progression once it begins
Epidemiological Feats:
- CJD: 1 case per year per million worldwide
- vCJD: 98% cases originated in UK
other conditions that may display subacute encephalitis sx:
Rickettsial diseases Rocky Mountain Spotted fever Lyme disease Bartonella or Anaplasma disease Tapeworm disease Syphilis
Congenital infection with subacute encephalitis occurring in the first or second trimester is associated with what abnormalities?
stillbirth, severe abnormalities such as liver and spleen enlargement, liver failure, hydrocephalus, convulsions, damage to the retina that can result in blindness
list come neglected parasite infections in the US
Chagas disease - Trypanosome cruzi, protozoan
Neurocysticercosis - Taenia sodium, tapeworm
Toxocariasis - Toxocara, roundworm
Toxoplasma - Toxoplasma gondii, protozoan
Trichomoniasis - Trichomonas vaginalis, protozoan
Toxoplasma (protozoa) is an ___________ intracellular parasite; and T. gondii has ______ host specificity, allowing it to attack at least 200 species of birds and mammals
obligate
low
For which disease processes are immunizations available?
a. cryptococcus neoformans
b. Listeria monocytogenes
c. Haemophilis influenzae
d. Streptococcus pneumoniae
e. Neisseria meningitidis
c, d, e
S/S of CJD (transmissible spongiform encephalopathy - prions)
altered behavior dementia memory loss impaired senses delirium premature senility
death usually occurs within 1 year of dx
what does spongiform damage confer
holes in the brain
PrP proteins
fx in normal brain development/function; altered in CJD and then begin to alter other Prp proteins = abnormal proteins; until they accumulate and cause holes in the brain
_______ can withstand prolonged autoclaving
prions
Rabies
only rhabdovirus that infects humans; zoonotic disease characterized by a fatal meningoencephalitis
Rabies S/S
Average inc. period is 2 weeks to even years depending on wound site, its severity, and the inoculation dose
–> inc. period is shorted in facial, scalp, or neck wounds because of closer proximity to the brain
Prodromal phase begins with FEVER, NAUSEA, VOMITING, HEADACHE, FATIGUE, and other nonspecific symptoms
*In the past if you got rabies you would die but now with intensive and long-term tx people are recovering
How does rabies infection work/V factors
infected animal saliva enters puncture site or is inhaled or inoculated through membranes of the eye
virus remains at trauma site for up to a week where it multiplies
virus gradually enters nerve endings toward the ganglia, spinal cord, and brain
viral multiplication throughout the brain is eventually followed by migration to diverse areas such as the eye, heart, skin, and oral cavity
infection cycle is completed when the virus replicates in the salivary gland and is shed into the saliva
V Factor: envelope glycoprotein allows virus to spread in CNS and invade certain neural cells
Primary reservoirs of rabies
wild mammals such as canines, skunks, racoons, badgers, cats, and bats that can spread the infection to domestic dogs and cats
Diagnosis of rabies
requires multiple tests
Reverse Transcriptase PCR is used with saliva samples; but must be accompanied by detection of antibodies to the virus in serum or spinal fluid
Direct fluorescent antigen testing
treatment of rabies
one of few infectious diseases for which a combination of passive and active postexposure immunization is indicated (and successful)
Tetanus
neuromuscular disease whose alternate name, lockjaw, refers to a early effect of the disease on the jaw muscle
Tetanus S/S
C. tetani releases a powerful exotoxin that is a neurotoxin, tetanospasmin, that binds to target sites on peripheral motor neurons in the spinal cord, brain, and sympathetic NS
—>toxin acts by blocking inhibition of muscle contraction = muscles uncontrollably contracting
First Symptoms: clenching of jaw, followed by extreme arching of the back, flexion of arms, and extension of legs
death most often occurs due to paralysis of resp muscles and then resp arrest
*Lockjaw confers the bizarre appearance of risus sardonicus (sardonic grin), which looks eerily as though the person is smiling
tetanus bacteria (G+) is a strict ___________
anaerobe
transmission/epidemiology of tetanus
endospores enter body through accidental puncture wounds, burns, umbilical stumps, frostbite, and crushed body parts
most cases are among geriatric pts and drug users
tetanus tx and prevention
patient with clinical appearance suggestive of tetanus should immediately receive antitoxin therapy with human tetanus immune globulin (TIG) and also Penicillin G
- –> vaccination with DTaP (diphtheria, tetanus, and cellular pertussis) for 1-3 month old babies (three injections two months apart)
- -> offers 10 years of protection
neonate protection = vaccinate pregnant mother
V Factor of tetanus
Tenanospasm exotoxin
Botulism
poisoning that results from the introduction of a toxin (exotoxin) into body tissues through ingestion of injection
—> is associated with eating poorly preserved foods, although it can occur as a true infection
Botulism S/S
sx are largely the same for all three forms
from the circulatory system, an exotoxin called the botulinum toxin travels to its principal site of action, the neuromuscular junction of skeletal muscles
—> effect of toxin is to prevent release of neurotransmitter acetylcholine which initiates the signal of muscle contraction = flaccid paralysis (opposite of tetanus)
usual time before onset of sx is 12 to 72 hours, depending on size of dose
neuromuscular sx first affect the muscles of the head and include double vision, difficulty in swallowing, and dizziness, but there is no sensory or mental lapse
–>later ex are descending muscular paralysis and respiratory compromise
Infant Botulism (66%)
infection followed by intoxication
- most common type of botulism in the US (approx. 140 cases annually)
- food source of cause, ie. raw honey has been implicated
- endospores are common in dust and soil
- endospore can gain foothold in intestine and normal biota in infants
Culture/dx: finding the toxin/organism in the feces confirms dx
Wound Botulism (14%)
infection followed by intoxication
- 3-4 cases per year in the US
- endospores enter puncture or wound and cause sx like in foodborne infection
- cases of this form have increased several-fold in the last several years due to IV drug use
Culture/dx: toxin should be demonstrated in the serum, or the organism should be grown from the wound
Foodborne Botulism (10%)
pure intoxication
- many infections occur in home-processed foods including canned vegetables, smoked meats, and cheese spreads
- endospores can be present on vegetables or meat at the time of gathering and are difficult to remove completely
- when contaminated food is put into jars and steamed in a pressure cooker that does not reach reliable pressure and temp, some endospores survive (botulinum endospores are highly resistant to heat)
Culture/dx: some labs attempt to identify the toxin in the offending food
- alternatively, if multiple pts present with the same sx after ingesting the same food, a presumptive dx may be made
- cultivation of Clostridium botulinum in feces is considered confirmation of fx because the carrier rate is very low
some reasons for botox (exploitation of exotoxin)
vanity migraine excessive sweating MS urinary incontinence tennis elbow
both Clostridium tetani and botulinum are endospore-forming _______, that does its damage through the release of exotoxin
anaerobe
Botulism treatment and prevention
CDC maintains a supply of antitoxin, which, when admin’d soon after dx, can prevent the worst outcomes of the disease
- -> pts also managed with resp and cardiac support
- > 5% mortality
Antitoxin, Penicillin G for wound botulism, supportive care
category A bioterrorism agent
which pathogen has evolved to make its rodent host less avoidant of cats?
Toxoplasma gondii (P) (Subacute Encephalitis)
What cellular structure do several of the organisms that cause meningitis share?
capsules
which of the following organisms is anerobic?
a. poliovirus
b. Cryptococcus
c. Clostridium
d. Coccidioides
c. Clostridium
ie. C. tetani and botulinum
Which disease is caused by an infectious agent that carries no nucleic acid?
a. rabies
b. CJD
c. polio
d. meningitis
b. CJD (prions)
the normal gut microbiota in adults, but not infants, inhibit the growth of which pathogen?
Clostridium botulinum
Infant Botulism
subacute encephalitis may be caused by
a. Toxoplasma gondii
b. Streptococcus agalactiae
c. Naegleria fowleri
d. Haemophilus influenzae
a.
Neisseria meningitidis
Streptococcus pneumoniae
Haemophilus influenzae
Listeria monocytogenes
Cryptococcus neoformans(AIDS patients, lots of testing, fungi)
Coccidioides immitis (fungus) (granuloma spherule formation)
Viruses
causative organisms of meningitis
Streptococcus agalactiae (G+) E. coli strain K1 (G-) Listeria monocytogenes (G+) Cronobacter sakazakii (G-)
causative organisms of neonatal and infant meningitis
Primary Amoebic: Naegleria fowleri (vehicle - swimming)
Granulomatous Amoebic: Acanthamoeba (direct contact)
causative organisms + transmission of Meningoencephalitis
Arboviruses ie. West Nile, La Crosse, Jamestown Canyon, St. Louis, Powassan, Eastern Equine viruses) (vector - arthropod bites)
Herpes Simplex 1 & 2 (vertical or reactivation)
JC virus (ubiquitous)
causative organisms of Acute Encephalitis
Toxoplasma gondii (P) - vehicle (meat)/oral-fecal route
Subacute sclerosing panencephalitis - persistence of measles virus
Prions - CJD or vCJD
causative organisms of Subacute Encephalitis
