LECOM Microbiology Lecture 7 Brain infections

Describe the difference between the blood brain barrier and the blood-CSF barrier

o Blood-CSF: controls the composition of the cerebral spinal fluid (CSF)

§ Separates the CNS from the rest of body.

§ More permeable than BBB

Explain the clinical presentation and symptoms of meningitis

o inflammation of meninges

§ Symptoms:

· Photophobia

· Abrupt fever

· Irritability

· Nuchal rigidity (stiff neck)

Explain the clinical presentation and symptoms of encephalitis

o inflammation of white matter

§ Symptoms:

· Abnormal behavior

· Altered consciousness

· Fever

· Confusion

· Seizures

List which organisms are responsible for meningitis or encephalitis

§ Neisseria menigiditis

§ Streptococcus agalactiae

§ Streptococcus pneumoniae

§ Haemphilus influenzae b (Hib)

what is the gram stain and morphology of Neisseria meningiditis

· Gram stain and morphology

o Gram-negative diplococci

what is the transmission and susceptible population for Neisseria meningitidis infections

· Transmission

o Respiratory droplets

· Susceptible population (community acquired)

o Military, college students, prisons, winter-spring

what is the virulence factor for Neisseria meningitidis

o LOS (lipo-oligosaccharide)- endotoxin

o Pili- attaches to organelles

o Capsule

§ Allows bacteria to cross the BBB

§ Antiphagocytic

§ Serotyping- A, B, C, Y, and W135

what is the clinical presentation of Neisseria meningitidis

o Meningococcal Meningitis

§ Abrupt fever, nuchal rigidity, irritability, photophobia

§ Sore throat, headache

§ Hemorrhagic skin rash

§ Fatal if untreated

what is the diagnosis and prevention for Neisseria meningitidis

· Diagnosis

o Gram stain of blood/CSF

o Culture: chocolate agar (not blood agar)

· Prevention

o There are two types of vaccines.

what is gram stain and morphology of Streptococcus agalactiae

· Gram stain and morphology

o Gram positive, cocci-chain

what is the transmission and susceptible population for Streptococcus agalactiae

· Transmission

o Colonization

§ Genitourinary tract

§ Gastrointestinal

· Susceptible population

o About 1 in 4 pregnant women are carriers

o Most common cause of meningitis in infants

what is the virulence factor for Streptococcus agalactiae

capsule

what is the clinical presentation of Streptococcus agalactiae

o Group B strep (Group A= pyogenes)

-Early and late-onset meningitis

what is the diagnosis for Streptococcus agalactiae

o Gram stain CSF

o Culture

§ Blood agar: beta-hemolytic

§ CAMP test

· Culture with S. aureus

o Leads to a larger hemolysis pattern

§ Bacitracin sensitivity

· It is resistant.

· A zone of inhibition will not appear where culture is treated.

what is the prevention for Streptococcus agalactiae

Getting tested for GBS bacteria and receive antibiotics during labor

what is the gram stain and morphology for Streptococcus pneumoniae

· Gram stain and morphology

o Gram positive diplococci

what is the transmission and susceptible population for Streptococcus pneumoniae

· Transmission

o Respiratory droplets

· Susceptible population

o Found in healthy populations

§ Throat or nasopharynx

o Symptoms

§ Productive cough (sputum may also have blood- will appear rust-colored in stain)

what is the virulence factor for Streptococcus pneumoniae

capsule

what is the clinical presentation for Streptococcus pneumoniae

o Pneumococcal Meningitis

§ Occurs after bacteremia, otitis media, or sinusitis

§ Symptoms

· Meningitis- nuchal rigidity, photophobia, irritability

· Neurological deficits

o Motor handicaps, seizures, intellectual disability, impaired hearing

§ Populations

· Children under 2 years

· Elderly (older than 65 years)

· Immunocompromised patients

what is the diagnosis (lab characteristics) and prevention for Streptococcus pneumoniae

· Diagnosis

o Gram stain CSF

o Culture

§ Blood agar: alpha-hemolytic (green color, partial hemolysis)

§ Optochin sensitivity test

§ Bile solubility test

· Bacteria cant survive

· Prevention

o Vaccine

what is the gram stain and morphology of Haemphilus influenzae b (Hib)

gram negative coccobacilli

what is the transmission and susceptible population for Haemphilus influenzae b (Hib)

· Transmission

o Respiratory droplets

· Susceptible population

o Children under 5 years (Unvaccinated)

what is the virulence factor for Haemphilus influenzae b (Hib)

o Capsule

§ Type B

· Polyribitol phosphate (PRP)

what is the clinical presentation for Haemphilus influenzae b (Hib)

o Hib Meningitis

§ Symptoms

· Nuchal rigidity, photophobia (meningitis symptoms)

· Babies will display:

o Irritability, poor feeding, appear inactive.

· Sequelae

o Deafness, delayed language development, intellectual disability

what is the diagnosis for Haemphilus influenzae b (Hib)

o Gram stain CSF/blood

o Chocolate agar

§ Factor V (NAD) and Factor X (heme)

o Antigen detection

§ Particle agglutination test

what is the prevention for Haemphilus influenzae b (Hib)

o Maternal antibodies

o Hib Vaccine

§ Given to infants starting at 2 months

· Targets the polyribitol phosphate (PRP)

Early onset meningitis

§ Seen within 7 days of birth*

§ Due to mother's colonized with GBS

· Birth canal

§ Can be fatal and those who survive have severe symptoms (blindness, deafness, epilepsy, and intellectual disability)

Late onset meningitis

§ Symptoms present 7 days or 3 months after birth*

· Due to exogenous source (ex: people coming to visit and contact baby)

· Can also be fatal.

Describe how early-onset meningitis caused by Streptococcus agalactiae can be prevented

o There is a decrease in Early-onset due to antibiotics.

§ There is no decrease in Late-onset due to inability to control who contacts the baby (exogenous source)

what are the characteristics of Naegleria fowleri

o Type of parasite

§ Free-living amoeba (doesn't need host)

§ Protozoan parasites

what is the geographic location/environment for Naegleria fowleri

Mainly fresh water

· Lakes, ponds, rivers, etc.

what is the lifestyle for Naegleria fowleri

Trophozoite stage (trophozoite in CSF)

what is the clinical presentation of Naegleria fowleri

§ Primary amebic meningoencephalitis (PAM)

· Symptoms begin about 5 days postexposure.

· Fatal about 5 days after symptoms onset

o Difficult to detect.

· First Stage PAM

o Severe frontal headache, fever, nausea, vomiting.

· Second stage PAM

o Altered smell and taste, stiff neck, seizures, altered mental status, coma, death

What are the lab characteristics and diagnosis for Naegleria fowleri

§ Negative for bacterial/viral causes

§ Microscopy of CSF

· Prescnece of trophozoites

§ PCR

· Detect DNA (not widely available)

§ Autopsy

what parasite is responsible for eating undercooked pork

Taenia solium

what is the geographic location/environment for Taenia solium

§ Africa, Mexico, India, China

§ Occasionally in U.S. (CA, TX, NM)

what is the lifestyle for Taenia solium

§ Ingest the cysts leads to GI issue

Ingest the eggs leads to cysticercosis

what are the clinical presentations for taenia solium: ingesting the eggs

· Cysticercosis -> Neurocysticercosis

o Usually presents in 3-5 years (up to 30 years)

§ Most common parasitic CNS infection

§ Think travelers and immigrants

o Symptoms

§ Seizures

§ Fever, headache, altered vision, meningitis, hydrocephalus, altered mental status

what are the clinical presentations for taenia solium: ingesting the cysts

· Symptoms:

o Diarrhea, abdominal discomfort, indigestion

o Often asymptomatic (proglottids)

what are the lab characteristics and diagnosis for Taenia solium

MRI

serology- detect antibodies in CSF

what is the structure, including genome, of Rabies virus

§ (-) ssRNA (can't use host machinery), enveloped, bullet-shaped.

how is rabies transmitted

§ US

· Racoons, foxes, bats, skunks

§ Worldwide

· Dogs

what is the replication cycle for Rabies

retrograde axonal transport

what is the clinical presentation of rabies

§ Incubation phase (weeks-months)

· Asymptomatic

§ Prodrome phase (2-7 days)

· Fever, chills, weakness, fatigue, itching at bite site

· Neurological symptoms

o Headache, photophobia

§ Neurologic phase (2-7 days)

· Encephalitic rabies

o Hydrophobia, pharyngeal spasms, agitation, hallucinations

· Coma, death

what is the susceptible populations for Rabies

§ Anyone bit by common animals that carry virus

what is the lab characteristics and diagnosis for rabies virus

§ History- being bit by animal

§ Negri bodies

· Neuronal cytoplasmic inclusions

§ Direct immunofluorescence

· Viral antigens

§ PCR

· Detect viral genome

o (-) ssRNA, enveloped, bullet-shaped

what is the prevention of rabies virus

§ Vaccinate animals

§ Pre-exposure prophylaxis

· Due to occupations (veterinarians, lab workers, park rangers, etc.)

§ Post-exposure prophylaxis

· Human rabies immune globulin (IgG) + rabies vaccine

o Injected at site of bite

· Rabies vaccine again on days 3, 7, and 14

What is the structure of Herpes-Simplex Virus 1 and 2

dsDNA, enveloped (nuclear envelope)

what is the transmission of Herpes-Simplex Virus 1 and 2

§ Secretions and direct contact

· Children and sexually active individuals at greatest risk

§ Latency sites

· HSV-1 (cold sores)

o Trigeminal ganglia

· HSV-2 (STIs)

o Sacral

what is the replication cycle of HSV 1 and 2

latency and reactivation stages

what is the clinical presentation of HSV-1

§ HSV-1 encephalitis

· Population: children and older adults

· Due to reactivation from trigeminal ganglia

· Symptoms

o Seizures, altered consciousness, ataxia, behavior changes, increased sexual activity

what is the clinical presentation of HSV-2

§ HSV-2 encephalitis

· Population: neonatal (birth canal)

· Symptoms

o Seizures, irritability, poor feeding, tremors

what is the susceptible population for HSV

§ HSV-1: children and older adults

§ HSV-2: babies

what is the lab characteristics and diagnosis HSV

§ Patient's age

§ PCR of CSF

· Detect HSV DNA (dsDNA)

§ CT and MRI