Epidemiology of Infections

Epidemiology of Common Infections

• The flu is a viral respiratory infection treated with fluids, rest, pain/fever reducers, and antivirals
  • Sympoms consist of fever, body aches, cough, and fatigue
• Mononucleosis is a viral infection (EBV) treated with rest, OTC pain medication, salt water gargles, and fluids
  • Presents with fatigue, swollen lymph nodes, body aches, rash, and fever
• Meningitis is a bacterial infection caused by Neisseria Meniginidits
  • Treatment involves the miningcoccal conjugate vaccine, antibiotics, and self-isolation
  • Symptoms of fever, soreness/muscle tightness, fatigue, stiff neck, and headache are present
• Streptococcus pneumoniae is a bacterial infection requiring daily antibiotics, rest, and fluids.
  • Evident with sore throat, fever, heavy head, and trouble maintaining homeostasis
• Herpes is a viral infection (HSV) requiring antiviral medication, safe sex practices, trigger/stress avoidance, and good hygiene
  • Common symptoms are cold sores, sore neck, fever, and painful urination

PCR (Polymerase Chain Reaction)

• PCR amplifies DNA into millions or billions of copies for detailed study
• Required components for PCR:
  • Thermocycler
  • DNA Sample
  • Taq Polymerase
  • Primers (2)
  • Free nucleotides
• The three steps of PCR:
  • Denaturation: Double-stranded DNA is heated and separates into single strands
  • Annealing: Primers attach to the template strand's binding site
  • Extension: Taq Polymerase creates complementary DNA strands using free nucleotides

BLAST

• BLAST contains known DNA sequences that you compare to a sequenced unknown DNA to identify pathogens
• Utilizes bioinformatics, a field combining computers, biology, and information technology to store/analyze genetic data

DNA Sequencing

• DNA sequencing determines the order of nucleotides
• A pairs with T, C pairs with G
• The order of operation is PCR, then DNA Sequencing, and then BLAST

ELISA (Enzyme-Linked Immunosorbent Assay)

• ELISA is an assay that produces qualitative (Yes/No) and quantitative (how much) results
• The 5 components of ELISA:
  • Antigen
  • Primary Antibody
  • Secondary antibody with enzyme
  • Substrate that produces a colored product

Antibiotics

• Penicillin stops cell wall formation, mainly affecting gram-positive bacteria
• Sulfonamides inhibit the cell's ability to grow and multiply, affects both gram-positive and gram-negative bacteria
• Tetracyclines inhibit protein synthesis (ribosomes) and affects both gram-positive and gram-negative bacteria
• Fluoroquinolones inhibit bacterial cell formation, affecting both gram-negative and gram-positive bacteria

DNA Transfer Methods

• Conjugation is a one-way DNA transfer between bacterial cells in contact via Pili
• Transduction uses a vector (bacteriophages or viruses) to transfer genetic material
• Transformation is the uptake of foreign DNA by a cell
• Strain one of bacteria is Streptomycin resistant, strain two is Ampicillin resistant

LB Agar Plates

• Results for E. Coli growth on LB agar plates with antibiotics:
  • LB Agar shows growth
  • LB Agar + Streptomycin shows growth for strain one, no growth for the other strain
  • LB Agar + Ampicillin shows no growth for strain one, growth for the other strain
    • LB agar + streptomycin + ampicillin shows no growth for either strain

Antibiotic Resistance

• Antibiotic resistance is when bacteria obtain DNA and are not affected by specific antibiotics
• Antibiotics target the least resistant bacteria first

Conductive and Sensory Hearing Loss

• Conductive hearing loss occurs when sound waves cannot pass through the outer and middle ear
  • The Rinne Test is administered for conductive hearing loss
• Sensorineural hearing loss occurs when the inner ear parts are damaged such as the cochlea or auditory nerve
  • The Weber test is conducted for sensorineural hearing loss, and a tuning fork is placed on the patient's forehead

Anatomy of the Ear

• Outer Ear
  • Pinna collects sound waves and sends to the auditory canal
  • The auditory canal collects sound and delivers to the eardrum
• Middle Ear
  • Ossicles (malleus, incus, stapes) amplify and transfer sound vibrations to the inner ear
  • Eustachian Tube balances air pressure between the middle ear and the throat
  • The tympanic membrane (eardrum) vibrates in response to sound waves
  • Oval window transmits sound vibrations from the stapes to the cochlea
• Inner Ear
  • Cochlea converts sound vibrations into nerve signals
  • Semicircular canals filled with fluid help with balance
  • Sensory hair cells detect sound vibrations, sending them to the brain
  • The cochlear nerve carries sound signals to the brain
  • Vestibule helps with balance and head position
  • Vestibular nerve carries balance information

Vaccines

• Toxoid vaccines first culture and isolate the toxin produced by the pathogen
  • The toxin is neutralized (formaldehyde) and put into a syringe
• Subunit vaccines remove a DNA fragment from a pathogen to immunize against it
  • The DNA segment is added to a yeast culture, then isolate the antigen, and fill the syringe
• Killed vaccines involve culturing and purifying the virus, then "killing" it with heat, radiation, or chemicals.
• Live attenuated vaccines involve culturing a virus in a non-human environment to weaken it
• Conjugate vaccines combine a weak antigen with a strong carrier protein through chemicals

Restriction Enzymes

• Restriction enzymes recognize specific DNA sequences and cut based on sequence
  • The cuts are called restriction sites
  • Sticky ends create recombinant DNA
• Plasmids are manipulated to carry a gene of interest into a cell to produce the desired protein.
  • Plasmids are cut with the same restriction enzyme as the gene of interest and ligase joins the DNA

Screening & Diagnostic Testing in Prenatal Care

Maternal Serum Screening

• Measures certain proteins/hormones in blood to estimate baby's risk for chromosomal conditions/neural tube defects
• It's noninvasive and gives early insights
• It only estimates risk and can cause worry or require follow-up testing

Ultrasound (NT & Anatomy Scan)

• Uses sound waves to create images so you can make sure the baby is growing correctly
• Assesses risk of Down syndrome and ensures baby's organs, limbs, spine are developing correctly
• Is safe, painless, and noninvasive
• NT scan is not a diagnosis, so abnormal results may need more tests.

Noninvasive Prenatal Screening (NIPS/Cell-Free Fetal DNA Test)

• Blood test analyzes baby's DNA in mother's bloodstream to screen for chromosomal disorders
• More accurate than traditional blood tests, especially in high-risk pregnancies
• Highly accurate and noninvasive, can be done at 10 weeks
• Does not diagnose, false positives/negatives can happen, and may not be covered by insurance

Diagnostic Testing (Chorionic Villus Sampling and Amniocentesis)

• CVS takes a piece of the placenta for testing, an amniocentesis collects amniotic fluid
• Recommended if other screenings show a high risk/family history of genetic disorders
• Provides a definite diagnosis and helps parents make decisions
• These are invasive procedures with a small risk of miscarriage/discomfort

Genetic Disorders

• Single Gene
  • Caused by mutations in one gene's DNA sequence, preventing protein production
    • Includes autosomal dominant, sex-linked, and recessive diseases such as:
      • Huntington's (autosomal dominant)
      • Duchenne Muscular Dystrophy (sex-linked)
      • Cystic Fibrosis (recessive)
• Multifactorial
  • Caused by a combination of environmental factors and multiple gene mutations, that can cause:
    • Alzheimer's Disease
• Chromosomal
  • Problems arise from missing or extra chromosomes through deletions, breaks, or rejoicings
    • Ex: Down Syndrome
• Mitochondrial
  • Rare, due to mutations in mitochondrial DNA passed from mother to child -Ex: Leber Heredity Optic neuropathy

Gene Therapy

• Gene therapy edits the human genome to remove genetic diseases by inserting or deleting genes

SNP (Single Nucleotide Polymorphism)

• A germline substitution of a single nucleotide at a specific position in the genome