Microbiology Notes From 4/16

Microbiology Notes From 4/16

Slides: 17-25

Chapter 25: Circulatory and Lymphatic System Infections

Infectious Mononucleosis and Burkitt Lymphoma

  • Also called the Kissing Disease or “Mono” is caused by Epstein-Barr virus (HHV4); direct contact spread; self-limiting after a month for healthy people. Signs/Symptoms: Fever, sore throat, fatigue, and/or enlarged lymph nodes in the neck. It most commonly occurs in adolescents and young adults. Burkitt Lymphoma: May occur in patients with malaria or HIV; Malignant B-cell lymphomas

  • Diagnosis: Antibody test; Biopsy

Ebola

  • BSL-4 Filovirus

  • Direct body fluid contact

  • Signs/symptoms: High fever and extreme tiredness, often accompanied by appetite loss, headache, and body pain.

  • Diagnosis: ELISA; PCR. No approved treatment

Human Immunodeficiency Virus (HIV)

  • HIV: Retrovirus; HIV- 1, HIV-2 (25.6 million people)

  • Transmission: Direct contact with body fluids

  • Three Stages based on CD4-T cell counts

  • (Stage 1– Acute HIV infection; Stage 2– Clinical latency; Stage 3– Acquired Immunodeficiency Syndrome (AIDS))

  • Clinical progression of HIV: Three stages

  • Diagnosis: Serological testing; PCR; Western blot

  • Treatments: No possible to cure; Antiretroviral therapy; Reverse transcriptase inhibitors; Protease inhibitors

Malaria

  • Plasmodium spp.

  • 214 million cases in 2015; 438,000 deaths; Mosquito transmission

  • Complex lifecycle: Multiple developmental stages; Antigenic variation

  • Diagnosis: Microscopic examination; EIA

  • Treatment/Prophylaxis: Chloroquine; Atovaquone; Mosquito control

Toxoplasmosis

  • Caused by Toxoplasma gondii

  • 22.5% of the population over 12 has been infected; Domestic cats shed in feces; Signs/Symptoms: In men, antisocial/high sex drive; In women, becomes a crazy cat lady

  • Diagnosis: Cysts in tissue specimens; CT; MRI

  • Treatment: Pyrimethamine; Sulfadiazine

Microbiology Notes From 4/16

Slides: 1-26

Chapter 26: Nervous System Infections

The Nervous System

  • Central Nervous System (CNS): Brain; Spinal Cord; Fluid that surrounds, protects, and nourishes tissue – cerebrospinal fluid (CSF)

  • useful for diagnosis of infection, obtained by spinal tap

  • Peripheral Nervous System (PNS): Nerves; Any disease affecting the nerves is called neuropathy

The Meninges and The Blood Brain Barrier

  • Coverings of the brain and spinal cord; Three layers: Innermost- Pia mater; Middle- Arachnoid mater; Outer- Dura mater

  • Blood Brain Barrier: Protects CSF from contamination; Most pathogens cannot pass through the blood-brain barrier to infect central nervous system tissues

Cells of the PNS and CNS

  • Neuron: Dendrites; Cell body – soma; Axon: Myelinated - with myelin sheath and Unmyelinated; Synapses: Pre-/Post-synaptic neurons; Neurotransmitters

  • Support cells: Glial cells

Meningitis, Encephalitis, and Meningoencephalitis

  • Inflammation of the meninges; Severe headache; Sensitivity to light (photophobia); Stiff neck (nuchal rigidity)

  • Encephalitis: Inflammation of the brain; Lethargy; Seizures; Personality changes

  • Meningoencephalitis: Inflammation of both brain and meninges

Bacterial Meningitis

  • Caused by Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae

  • Respiratory secretion spread; Cross mucus membranes and enter the blood; Death in hours in some cases

  • Diagnosis: Analysis of CSF; Treatment; Based on the type of meningitis

Meningococcal Meningitis

  • Caused by Neisseria meningitidis

  • Death within hours in some cases; Irreversible nerve damage; Infants, adolescents, young adults; Outbreaks in schools

  • Diagnosis: Petechial rash on the skin; CSF analysis

  • Treatment: Cephalosporins; Vaccine

Pneumococcal Meningitis

  • Caused by Streptococcus pneumoniae

  • Normal microbiota; Leading cause since the introduction of Hib

  • Diagnosis: CSF gram stain; Latex agglutination; Cultures

  • Treatment: Broad-spectrum – Levofloxacin, cefotaxime, penicillin; Vaccines

Haemophilus influenzae Type B

  • Hib: Encapsulated Gram-negative coccobacilli; 16 Virulence factors

  • Diagnosis: PCR; CSF smear

  • Treatment: Vaccine; Doxycycline; Fluoroquinolones

Neonatal Meningitis

  • Caused by Streptococcus agalactiae

  • Up to 3 months of age; Bacteria transferred from the mother's vagina; Signs/Symptoms

  • Diagnosis: CSF cultures; PCR, RT-PCR

  • Treatment: Beta-lactam antibiotics; 10 % mortality rate even with treatment

Tetanus

  • Caused by Clostridium tetani

  • Noncommunicable disease; Localized, Cephalic, General, Neonatal tetanusSigns/Symptoms – opisthotonos(your body will lock up), lockjaw

  • Diagnosis: Clinical signs/symptoms; Culture

  • Treatment: Assisted breathing; Metronidazole; Vaccine

Botulism

  • Caused by Clostridium botulinum

  • Intoxication – botulism toxin; Wound botulism; Signs/Symptoms

  • Diagnosis: Clinical symptoms; Patient history; Culture

  • Treatment: Antitoxin; Recovery takes months

Listeriosis

  • Caused by Listeria monocytogenes

  • Gram(+) rod; Foodborne pathogen; Virulence factors; Signs/Symptoms

  • Diagnosis: Culture; MALDI-TOF

  • Treatment: Ampicillin; Gentamicin

Hansen’s Disease/Leprosy

  • Caused by Mycobacterium leprae

  • Acid-fast bacterium; PNS; Signs/Symptoms: the blacking of the nose

  • Diagnosis: Clinical signs and symptoms; PCR

  • Treatment: Dapsone; Rifampicin; Clofazimin

Rabies

  • Caused by Rhabdoviridae

  • RNA viruses; Transmitted through bite of infected animal

  • Raccoons -> Bats -> Skunks -> Foxes; Vaccines for wild animals

  • Diagnosis: Clinical case history; Negri bodies; RT-PCR

  • Treatment: Vaccination

Poliomyelitis/Polio

  • Fecal-oral, or droplet transmission; Signs/Symptoms

  • Diagnosis: RT-PCR; Serological testing

  • Treatment: Vaccination(2); Supportive measures

Polio Vaccines

  • Salk Vaccine: Inactivated vaccine; Injection; Effective against 3 serotypes of polio

  • Sabin Vaccine: Attenuated virus; Oral delivery; Effective against 3 serotypes of polio

  • Eradication efforts: Polio is currently endemic to a few countries; Vaccine efforts have been disrupted

Transmissible Spongiform Encephalopathies

  • Acellular infections agents; Prions (infectious proteins); Causes Creutzfeldt-Jakob disease(CJD-is a fatal, degenerative brain disorder that causes rapid loss of brain function)

  • Diagnosis: Histological examination of brain biopsies; RT-QuIC

  • Treatment: Supportive

Cryptococcal Meningitis

  • Caused by Cryptococcus neoformans

  • Yeast produces a thick capsule, found in soil; Healthy individuals typically recover; Signs/Symptoms

  • Diagnosis: Culture; Treatment; Amphotericin B plus Flucytosine for 10 weeks

Amoebic Meningitis

  • Caused by Naegleria fowleri

  • Free-living in soil and water; A rare disease, transmission typically occurs while swimming in warm water; Only 3/138 patients in the US have survived; Signs/Symptoms

  • Diagnosis: Observation of CSF; PCR; Indirect immunofluorescence

  • Treatment: Experimental drug – Phosphotidylcholine

Human African Trypanosomiasis/Sleeping Sickness

  • Caused by Trypanosoma brucei

  • Transmitted via the tsetse fly; Signs/Symptoms: early- swelling of cervical lymph nodes(Winterbottom’s sign)

  • Diagnosis: Clinical symptoms; Observation of samples (blood, CSF, Lymph)

  • Treatment: Pentamidine; Suramin

Neurotoxoplasmosis

  • Caused by Toxoplasma gondii

  • Eating infected meat, ingesting oocysts shed in cat feces; Signs/Symptoms

  • Diagnosis: MRI or CAT scans; CSF observation; RT-PCR

  • Treatment: Pyrimethamine, sulfadiazine, folinic acid

Neurocysticercosis

  • Caused by Taenia solium

  • Pork tapeworm; Eating contaminated meat, fecal contamination; Signs/Symptoms – cysts in the brain called cysticerci

  • Diagnosis: MRI, CT; EIA; ELISA

  • Treatment: Albendazole; Praziquantel