Intro to Infection (Exam 1) Flashcards
What is an infection?
-Colonization of a host by a MICROBIAL species
-Localized or Systemic
What causes an infection?
Common: Virus (Only DNA or RNA surrounded by a protein cell.) (Most have a host cell) Bacteria (much larger than a virus and are single celled with one strand of DNA)
Rare: Fungal-Spore forming organisms. Protozoa-Typically live in water environment. Helminths- parasitic worms. Prions- Proteinaceocus infections particles. Misfolded proteins that attach and cause terrible disease.
Modes of Transmission
Microorganism must have a RESORVOIR. Can live in water animals humans
Two main types of transmission. Direct and Indirect
Direct transmission
Spread through direct contact of organism. Sneezing, coughing, sex, kissing.
Indirect transmission
Vehicle or Vector Born
Vehicle: Food, Water, Blood. HEP A through contaminated food.
Vector: Something carries disease. Ticks and etc.
How do organisms get into the body. Portal of entry
-Oropharynx and Nasopharynx (Airway, lungs, stomach, and GI tract)
-Genitoruinary Tract (Urninary tract. STD. Catheters
Biggest Barrier to prevent portal of entry
Our skin. Tight Cell Junctions
Translocation. Portal of Entry
-Movement of bacteria across the intestinal lining
-Occurs frequently in the PEROTINEAL cavity
-Bloodstream
Blood. Portal of Entry
-Blood transfusion contamination
-Needle sticks
Maternal-Fetal Transmission. Portal of Entry
-Cross the placental barrier and directly to fetus
-Can occur during childbirth
Largest Portal of Entry
The skin. So it is the biggest barrier and biggest risk
Stages of Infection
Incubation Stage
Prodromal Stage
Acute Stage
Convalescence Stage
Resolution Stage
Incubation Period of infection
The time from when the microorganism gets into the body to when symptoms first appear.
Microorganism is in body growing and spreading with no symptoms
Prodromal Stage of infection
-Onset of non-specific symptoms. Not feeling good a little extra tired. Small fever. No real full out symptoms
Acute stage of Infection
Full blown symptoms. Can not get out of bed.
Convalescent Stage
Starting to fill better and symptoms begin to start disappearing
Resolution Stage
-Complete elimination of the pathogen from the body. Some infectious agents never get to this point. Chicken Pox lives dormant in you for the rest of your life. Never inter resolution stage
The Infectious Process (6 processes)
- injury
- Increased Permeability
- Immigration of leukocytes
- Phago-cytosis
- Exudate
- Systemic Symptoms
Infectious process: Injury Stage
-Initial insults to area occurs
-Fell on dock and cut hand
-Short period of vasoconstriction. To stop bleeding and prevent movement of invading organisms
-Prolonged period of VASODILATION. Allows for blood cells to flow freely into area and bring immune cells to the area. Contributes to symptoms of inflammation. Warmth-Redness-Swelling
Infectious Process: Increased Permeability Stage
-Happens at site of injury
-Fluid begins to pulled out of vascular space. Fluid starts going into the tissue space.
-Fluid moves out of the vessel to site of injury. This allows from the immigration of Leukocytes
Infectious Process: Immigration of Leukocytes Stage
-From the fluid out of the vascular space. Neutrophils attracted to area of injury.
-Neutrophils attach to the endothelium of injured cells and move through into surrounding injured tissues
Infectious Process: Phagocytosis Stage
-The white blood cells begin PHAGOCYTOSIS. They recognize and engulf and destroy the evader cells
Infectious Process: Exudate
-The stuff that comes from fluid leaking from blood vessels along with cells and derbis from phagocytosis.
- Its’ purpose is to transport the leukocytes to injured area, dilute toxins that might be present, and transport nutrient fro healing process.
-Helpful in the beginning but can become a problem.
Infectious Process: Systemic Symptoms
-Last part
-Can occur if the process doesn’t remain localized
-Total body response. Stimulate fever
-Helps body concern heat. Stimulates defense mechanisms to help rid body of organisms. In heat, some bacteria less virulent and divide slower.
-Higher body temp also improves our own immune system. Neutrophil and macrophage function better and improves antibody release and T-cell activation
If an infection sticks around longer is systemic infection.
Colonization occurs.
Colonization
Inhabit a specific body site
Do not cause S/S of infection
People who have non symptomatic infection on skin and etc.
Infection
-Clinical S/S of illness, inflammation
-Tissue damage and invasion of micro-organsim
Who do we know when there is an infection
-Vital Signs. Typically increase because higher rate
-Labs: cultures-urinlysis
Cultures
-Gram Stain: Returned within hours. Takes a STAIN of the bacteria and shows whether gram + or gram -. Ex: Gram + cocci in clusters. GRAM - more dangerous
-Culture and Sensitivity: Takes at least 24 hours for a basic result. May take up to 72 hours for full identification and sensitivity pattern.
What can you culture?
-Sputum
-Urine
-Blood
Culturing Blood
-Aerobic and Anaerobic Bottles
-Ideally 2 sets obtained
-Ideally at least on a PERIPHERAL stick
-High likelihood of skin contamination
Urine Culture: Urinalysis
-Dipstick: pH 5.0-9.0
-Nitrites (normal negative): Postive for nitrites is indicative of bacteria infection
-Leukocyte esterase (normal negative) Enzyme produced by WBC’s. Indicates leukocytes in the urine which can mean infection
-Blood: Normal = <5 RBC’s. (If higher can be indicative of infection)
Infections within the healthcare setting
-Nosocomial infections. (More virulent) (Drug resistance HUGE problem)
-MRSE-CRE-MDRO. Resistant organsims.
Superinfections
-New infection that occurs during treatment for a different infection
-Typically caused by a resistant organism
-GI tract and Skin
Superinfection: C-Diff
Clostridium Difficile
-Normal intestinal flora killed by antimicrobial administration.
-C diff able to grow without normal control factor
-Orange watery diarrhea. Abdominal cramping and tenderness. Can occur days to months after antibiotic treatment
-Do not culture C.diff. USE a PCR
-Treatment with PO/IV metronidazole (Flagyl) or PO Vancomycin
-Never give antidiarrheal medications until sure patient does not have C. DIFF
-Pseudomembranous colitis: Life threatening. Dilation of the colon which may need decompression. May require surgery
Superinfection: Candidiasis
-Antimicrobial Agent kill normal flora along as the pathogens they are supposed too. Which can cause overgrowth of fungus.
-Typically occurs in the mucous membranes. Oral/Vaginal. (Thrush is mouth)
To prevent: Mycostatin: Swish and spit anti-fungal medication. Can also be in vaginal suppositories. Nystatin: Anti-fungal powder. Think athletes foot spray/powder
