Intro To Infection Flashcards
Reservoir
Habitat microorganisms need to grow (humans, water, organisms)
direct mode of transmission
Kiss, sex, touch, droplet, contaminated soil
Indirect mode of transmission
Airborne, vector (comes from animal host), vehicle born (comes from water, food, blood (Hepatitis A))
Portals of entry
Oropharynx, nasopharynx, genitourinary, skin, translocation, blood, maternal-fetal transmission
Body’s best defense
Skin
Translocation
Movement of bacteria across intestinal lining, often in peritoneal cavity (gut leaks), to bloodstream
Maternal-fetal transmission
Cross placenta or during childbirth (Zika)
Stages of infection
Incubation, prodromal, acute stage, convascelent, resolution
Incubation
Btwn pathogen entering body and when sx appear
Prodromal
Nonspecific mild sx
Acute stage
When person is ILL; specific sx
Convalescent stage
Coming down from illness and getting better
Resolution
Pathogen gone; some people never reach this stage
Infectious process
Injury, increased permeability, Immigration of leukocytes, phagocytosis, exudate, systemic sx
Injury
Initial insult to area, short period of vasoconstriction to stop blood flow and prevent movement of invading organisms followed by prolonged vasodilation bringing blood to area; get 5 signs of inflammation
Increased permeability
Fluid pulled out of vascular space and vessel to place of injury
Immigration of leukocytes
Neutrophils attracted to area of injury and attach to endothelium; also some eosinophils, NK cells, monocytes
Phagocytosis
Occurs when WBCs reach area, specifically neutrophils and monocytes; recognize, engulf, destroy organisms
Exudate
Exudate transports leukocytes to injured area, dilutes toxins, transports
systemic sx
Occurs if infection doesn’t stay localized; total body response stimulates increase of hypothalamic fever set point, helping the body conserve heat and stimulating defense mechanisms to help rid the body of organisms (some bacteria is less virulent and divides slower in heat; also improves antibody release and T-cell activation)
Colonization
When pathogens inhabit specific body sites and bacterial growth is at a minimum so no s/s of infection; inactive infection but can become active
How to know when infection occurs
VS, labs—cultures, urinalysis, sputum, blood
Gram stain
Stain of bacteria shows if gram negative or positive, gives shape and arrangement of bacteria; gram negative is more dangerous bc has a capsule that hides the bacterial antigens, making it harder to fight
Blood, urine, sputum culture
Takes 24h basic, 72h for full ID and sensitivity (what drug it is sensitive to (susceptibile) and what wont work (resistant)), watch for needle sticks, get 2 bottles, at least 1 from peripheral stick, get 1 aerobic, 1 anaerobic bottle
Urinalysis
Normal is 5-9 pH, no nitrites, leukocytes, epithelial cells, RBCs under 5
Nosocomial infection
Get in HC setting, spread quick and high chance of drug resistance; MDRO, MRSA, CRE (resistant to whole class)
Superinfection
New infection that occurs during tx for a different infection that involved antibiotics (antimicrobials often kill healthy flora too, especially in GI tract)
C. Diff
Extreme diarrhea, cramps and tenderness caused by normal GI flora being killing by antimicrobials; can occur months after antibiotics; identified with PCR test and treated with vancomycin and metronidazole (not anti diarrheal bc need to get the bacteria out)
Pseudomembranous colitis
Life threatening condition that can be caused by C. Diff in which the colon dilates with air; may require surgery for colon decompression
Candidiasis
Fungus overgrowth caused by antimicrobial agents killing healthy flora; often in mucus membranes like mouth (thrush), vagina, esophagus, skin surface; treat with mycostatin (antifungals) and prevent with nystatin powder
