Week 1 Intro to Infection Flashcards
WHAT IS AN INFECTION?
- Colonization of a host by a MICROBIAL species
- Can be localized= in a specific place
- Systemic= spread to several regions/areas of the body
WHAT CAN CAUSE AN INFECTION?
Virus, bacteria, fungi, protozoa, helminths, prions
WHAT CAN CAUSE AN INFECTION? VIRUS
only DNA or RNA, surrounded by a protein shell
Cannot do anything without host cell
Covid, AIDS, chicken pox, influenza
WHAT CAN CAUSE AN INFECTION? BACTERIA
much larger than a virus, single-celled organisms
Reproduce inside or outside of cell, 1 strand of DNA
Strep, TB, UTIs
WHAT CAN CAUSE AN INFECTION? FUNGI
spore-forming organisms
yeast infection
WHAT CAN CAUSE AN INFECTION? PROTOZOA
live in water
malaria
WHAT CAN CAUSE AN INFECTION? HELMINTHS
parasitic worms
round worms, hook worms
WHAT CAN CAUSE AN INFECTION? PRIONS
proteinaceous infectious particles, only composed of protein
Mad Cow disease
Resorvoir
habitat where organism lives and grows
humans, animals, insects, environment
Direct vs indirect
Direct: Kissing, sex, direct contact w/ environment, droplets (pertussis,
meningitis)
Indirect: airborne (measles)
Vehicle vs Vector born
Vehicle: Food, h2o, blood. (food contaminated with Hep A)
Vector born: Mosquitos carry Malaria
HOW DO ORGANISMS GET INTO THE BODY?
PORTAL OF ENTRY
- Oropharynx & Nasopharynx
- Bronchial airways, lungs, stomach and GI tract
- Genitourinary tract
- Urinary tract
• Bodies biggest barrier = SKIN
- Translocation
- Movement of bacteria across the intestinal lining
- Occurs frequently in the PEROTINEAL cavity
- Bloodstream
- Movement of bacteria across the intestinal lining
- Blood
- Blood transfusion contamination
- Needle sticks
- Maternal-Fetal Transmission
- Cross the placental barrier and directly to fetus
- Can occur during childbirth
STAGES OF INFECTION
- Incubation period: mircroorganism gets in, first symptoms, growing
- Prodromal stage: onset of non-specific syptoms
- Acute stage: specific symptoms, can’t get out of bed
- Convalescent stage: symptoms get better
- Resolution phase: pathogen eliminated from body, exception –> chickenpox
The Infectious Process
- Injury
- Increased permeability
- Immigration of leukocytes
- Phagocytosis
- Exudate
- Systemic Symptoms
INFECTIOUS PROCESS: INJURY
• Initial insult to area occurs
- Short period of vasoconstriction
- To stop bleeding & prevent movement of invading organisms
- Prolonged period of VASODILATION
- Allows for blood to flow freely into area
- Brings immune cells to the area
- Contributes to symptoms of inflammation
- Warmth, redness, swelling
INFECTIOUS PROCESS: INCREASED PERMEABILITY
- At site of injury:
- Fluid pulled out of vascular space
- **Because injury rarely occurs directly in vascular space (blood vessel)
- Fluid moves out of vessel to the place of injury
- Fluid pulled out of vascular space
INFECTIOUS PROCESS: IMMIGRATION OF LEUKOCYTES
• From the fluid out of the vascular space neutrophils attracted to area of injury
• These neutrophils attach to the endothelium of injured cells and move
through into surrounding injured tissues
• Other cells involved: eosinophils, NK cells, monocytes
INFECTIOUS PROCESS: PHAGOCYTOSIS
• Once leukocytes (white blood cells) make it to area of injury, PHAGOCYTOSIS
can occur
• Neutrophils and monocytes are the specific WBCs involved
• They recognized, engulf, and destroy invading organisms
INFECTIOUS PROCESS: EXUDATE
• Exudate: the ‘stuff’ that comes from fluid leaking from blood vessels, along
with cells and debris from phagocytosis
• Its’ purpose is to transport the leukocytes to injured area, dilute toxins that
might be present, and transport nutrients for the healing process
- Types:
- Serous
- Serosanguinous
- Purulent
- Hemorrhagic
INFECTIOUS PROCESS: SYSTEMIC SYMPTOMS
• Can occur if infectious process doesn’t remain localized
- Total body response stimulate the hypothalamic fever set point
- Fever set point increases
- Helps body conserve heat
- Stimulates defense mechanisms to help rid body of organisms
- In heat, some bacteria less virulent and divide slower
- Improves our OWN immune system
* Better neutrophil and macrophage function
* Improves antibody release and T-cell activation
- Fever set point increases
Colonization vs infection
Colonization:
Inhabit a specific body site
Do not cause S/S of infection
Infection:
Clinical S/S of illness, inflammation
Caused by tissue damage r/t invasion of micro-organism
CULTURES
- Gram stain
- Returned within hours
- Takes a STAIN of the bacteria and shows whether gram (+) OR gram (-)
* Also shows shape and arrangement
* Ex. Gram (+) cocci in clusters
- 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
- Aerobic and anaerobic bottles
- Ideally 2 sets obtained
- Ideally at least one a PERIPHERAL stick
- High likelihood of skin contamination
URINE CULTURE: URINALYSIS
- Dipstick
- pH 5.0-9.0 normal
- Nitrites (normal negative)
- Bacteria change nitrate into nitrites
- So positive for nitrites indicative of bacteria
- Leukocyte esterase (normal negative)
- Enzyme produced by WBCs
- Indicates leukocytes in the urine and indicative of infection
- Blood (normal <5)
- If higher can be indicative of infection
INFECTIONS WITHIN THE HEALTHCARE SETTING
- Nosocomial –> infections that occur while in a healthcare facility
- These infections are more virulent
- Drug resistance HUGE problem
- MRSA- methicillin resistant Staph aureus
* Resistant to specific drug - CRE- Carbapenem resistant enterobacteriaceae
* Resistant to entire class of medications
• MDRO- multi drug resistant organism
SUPERINFECTIONS
- New infection that occurs during treatment for a DIFFERENT infection
- Typically caused by a resistant organism
• The antimicrobials we use to treat initial/primary infection, inhibit or kill
NORMAL helpful flora
• Typically occurs within the GI tract
• Skin or mucosal surfaces
SUPERINFECTION: C DIFF
- Normal intestinal flora killed by antimicrobial administration
- C diff able to grow without normal control factor
- What does it look like:
* Diarrhea- orange like color, watery
* Abdominal cramping and tenderness
* Can occur days to months after antibiotic treatment - Identify with stool for C. diff toxin= PCR
* NOT CULTURE
How do you treat C Diff?
With PO/IV metronidazole (Flagyl) or po vancomycin
What do you not give to C Diff patients?
antidiarrheal meds; until sure patient does not have C Diff
Complications of C Diff
- Pseudomembranous colitis
- Life threatening
- Dilation of the colon which may need decompression (air removal)
- May require surgery
SUPERINFECTION: CANDIDIASIS
• Antimicrobial agents kill normal flora along as the pathogens they are.
supposed too
- Can cause an overgrowth of fungus
- Typically occurs in the mucous membranes
* Oral/vaginal
* Thrush when it is in the mouth
- Typically occurs in the mucous membranes
- Can also descend into the esophagus
- Skin surfaces
• Try and prevent this
• Mycostatin- swish and spit anti-fungal medication
• Can also be in vaginal
suppositories
• Nystatin- antifungal powder
• Think athletes foot spray/powder
