Introduction to Infection Flashcards
Infection
Colonization of a host by a microbial species
-Can be localized or systematic (whole body)
Cause of infection
Common:
-Virus
-Bacteria
Rare:
-Fungal
-Protozoa
-Helminths
-Prions
Virus
-Only DNA or RNA, surrounded by a protein shell
-Viruses have to have host to divide and multiply
Ex. COVID, Chickenpox, Influenza
Bacteria
-Much larger than a virus, single-celled organisms
-Can reproduce inside or outside of cells
-Adapt & suppress human body defenses
Ex. Strep, TB, UTI
Fungal
-Spore forming organism
Ex. Yeast infection
Protozoa
Typically live in water/environment
Ex. malaria
Helminths
Parasitic worms
Ex. Roundworm, hookworm
Prions
Proteinaceocus infectious particles, only composed on protein
-Rarest
-Misfolded proteins (small) that attach to other proteins
Ex. Madcow disease (aka creutzfield-jacob disease)
Microorganisms must have a _____
Resorvoir
Resorvoir
Habitat where organism usually lives and grows
-Can be human, animals, insects, environments
Direct mode of transmission
-Direct contact w/ contamination
-Kissing
-Sex
-Soil or vegetation
-Droplet: sneezing or coughing
Indirect mode of transmission
-Airborne or droplet (nuclei stay in air)
Ex. Measles, TB
Vehicle
Indirect transfer of infectious material through water, food, blood
Ex. Hep A (food)
Vector
Something else carries disease like ticks, mosquitoes, fleas
Ex. Malaria, Rocky mnt spotted fever, Lyme disease
How do organisms get into the body? Portal of entry?
-Oropharynx
-Nasopharynx
-Genitourinary tract: STDS, Catheter
-Translocation
-Blood
-Maternal-Fetal transmission
-Wounds
-Cuts
-Skin integrity issues
What is the bodies biggest barrier to organisms getting into the body?
The Skin
Translocation
-Movement of bacteria across the intestinal lining
-Occurs frequently in the perotineal cavity
-Bloodstream
Ex. Infection in blood & blood takes nutrients to bone can get bone infection
Blood Portal of entry
-Blood transfusion contamination
-Needle sticks
Maternal-Fetal transmission
-Cross the placental barrier and directly to fetus
-Can occur during childbirth
Ex. Zika, listera
What are the stages of infection?
- Incubation period
- Prodromal stage
- Acute stage
- Convalescent stage
- Resolution phase
Incubation
Time when microorganisms gets into body to when symptoms 1st appear. Typically no symptoms it is just growing and multiplying
Prodromal stage
Onset of nonspecific symptoms like not feeling goof or extra tired
Acute stage
Specific S/S, full blown can’t get out of bed
Convalescent stage
Coming out of acute stage, symptoms starting to get better, illness disappearing
Resolution phase
Pathogen is eliminated from your body
The infectious process (aka inflammatory process)
Process where body begins fighting somethings thats going on
- Injury
- Increased permeability
- Immigration of leukocytes
- Phagocytosis
- Exudate
- Systemic symptoms
The infectious process: Injury
-Initial insult to area occurs
-Short period of vasoconstriction followed by longer period of vasodilation
Purpose of vasoconstriction in Injury stage
To stop bleeding & prevent movement of invading organisms
Purpose of vasodilation in 1. injury phase
-Free flow of blood to injury site
-Bring immune cells (WBCs)
-Contribute to inflammation: warmth, redness, swelling
The infectious process: 2. Increased permeability phase
At site of injury fluid pukked out of vascular space to site of injury
-Becomes leaky and permeable
The infectious process: 3. Immigration of leukocytes phase
Neutrophils attracted to area of injury
-Neutrophils attach to endothelium of injured cells and move through into surrounding injured tissue
-Eosinophils, NK cells, monocytes involved too
The infectious process: 4. Phagocytosis Phase
-Once leukocytes make it to injury site, phagocytosis occurs
-Neutrophils and monocytes recognize, engulf, and destroy invading organisms
The infectious process: 5. Exudate Phase
-Exudate: the stuff that comes from fluid leaking from blood vessels, along with cells and debris from phagocytosis
-purpose is to transport leukocytes to injured site, dilute toxins, and transport nutrients for the healing process
-Types: Serous, Serosanguinous, Purulent, Hemorrhagic
The infectious process: 6. Systemic Symptoms Phase
-Occurs if infectious process doesn’t remain localized
-total body response
-Fever set point increases
What does a fever do for the body?
- Conserve heat
- Stimulate defense mechanisms to rid body of organisms
- In heat, some bacteria less virulent and divide slower
- Improves our own immune system: improve neutrophil and macrophage function & improve antibody release and T-cell acivation
What happens if we don’t get rid of infection and it goes on past systemic infection?
Colonization or injection
Colonization
-Inhabit a specific body site but doesn’t cause S/S of infection
-Immune system keeps it to a minimum
Ex. Non-symptomatic staph infection on skin or vancomycin resistant entercoccus
-Colonization w/o infection can turn into infection if immune system compromised
Infection
-Clinical S/S of illness, inflammation
-Caused by tissue damage r/t invasion of microorganisms
How do we know there is an infection?
Vital signs: Temp, HR, RR, Higher metabolic rate
Labs: cultures, urinalysis
Gram stain
-take body fluid and stain it
-returned within hours
-Gram + or Gram -
-Gram - more dangerous due to camouflagedC
Culture and sensitivity time
Takes atleast 24 hours for basic result and 72 hours for full identification and sensitivity pattern
What can you culture
-Sputum
-Urine
-Blood: Aerobic & Anaerobic bottles, peripheral stick, skin contamination, 2 sets preferred
Septic
infection of blood
What is normal urine suppose to include?
No bacteria
No Leukocyte esterase
No nitrites
<5 WBC
<5 RBC
<5 Epithelial cells
pH 5.0-9.0
When bacteria is found in urine _____ becomes ______
nitrates becomes nitrites
Nosocomia
Infections that occur while in healthcare facility
-more virulent
Drug resistant bacteria:
- MRSA: resistant to specific drug
- CRE: resistant to entire class of medications
- MDRO: Multi drug resistant organism
- VRE
Superinfections
New infection that occurs during treatment for a different infection
-Antimicrobials we use to treat initial/ primary infection, inhibit or kill normal helpful flora
-GI tract, skin, mucosal surfaces
C-diff Superinfection
Clostridium Difficile
-Normal intestinal flora killed by antimicrobial administration
-able to control w/o normal control factors
-can occur days to months after antibiotic treatment
-IV antibiotics or intense oral antibiotics
Identification and Treatment of C-diff
-Identify in stool by PCR
-Treat with PO/IV metronidazole (flagyl) or PO vancomycin
-NEVER give antidiarrheal meds
Complications of C-diff
Pseudomembranous colitis
-Life threatening
-Dilation of the colon which may need decompression (Air removal)
-May require surgery
Candidiasis Superinfection
-Yeast infection
-Antimicrobial agents kill normal flora with the pathogen intended to kill
-Overgrowth of fungus
-Oral (Thrush, vaginal, esophagus, Skin)
How do you prevent Candidiasis
- Mycostatin- swish & spit anti-fungal medication
- Nystatin- Antifungal powder, think athletes foot spray/ powder
