bacterial pathogens quick flashcards

what is virulence

the capacity of a microbe to cause disease

what is pathogenesis

refers to the development of disease

examples of opportunistic bacteria infections

streptococcus pneumoniae cause pneumococcal pneumonia

staph. epidermidis causes IV line infection

what does contracting a disease depend on

virulence of the microbe

inoculum

site of infection

host susceptibility & capacity to resist

what are the portals of entry for infection

ingestion

inhalation

penetration

sexual

what are fimbriae and pili

attach bacteria to the host cells

what are slime layers and capsules

help bacteria avoid the immune system

what is a biofilm

protective communities of bacteria

eg dental plaque

what are invasins

proteins that allow the bacteria to enter the cell by phagocytosis

what is the importance of iron in infection

iron is essential for bacterial growth

many bacteria are able to bind human transferrin, lactoferrin, ferritin and hemin and use these as their iron source

what is collagenase

bacterial enzymes that breaksdown collagen

spread of pathogen through tissue

eg C. perfringens

what is streptokinase

bacterial enzyme that dissolves fibrin clots

spread of pathogen through tissue

what is lecithinase

bacterial enzyme that breaksdown lecithin (cell membrane component)

what is hyaluronidase

bacterial enzyme that breaks down hyaluronic acid (cement between cells in tissue)

spread of pathogen through tissue

what are exotoxins

toxins produced by pathogens which diffuse from the cells

what are endotoxins

toxins which are actual components of the bacterial cell envelope

high concentration results in endotoxic or septic shock

results from excessive immune response

lipopolysaccharide or peptidoglycan

what are type I toxins/superantigens

exotoxin

results in excessive immune response

what are type II toxins

exotoxin

damage host cell membranes

what are type III toxins or A-B toxins

exotoxin

B-component brings toxin to host cell

A-component causes damage to cell

what are some bacteria that cause skin infection

staphylococcus aureus - stye, folliculitis, etc

streptococcus pyogenes - necrotizing fasciitis

pseudomonas aeruginosa

what are some bacteria that cause respiratory tract infections

ear, sinus - streptococcus pneumoniae

throat - streptococcus pyogenes

lungs - streptococcus pneumoniae, mycobacterium tuberculosis

what are some bacteria that cause tissue infections

brain - neisseria meningitidis

heart - oral streptococci and staphylococci

what is infective endocarditis

inflammation of endocardium

alpha-hemolytic streptococci from mouth (slow)

staphylococcus aureus (fast)

what is rheumatic fever

complication following pharyngitis

heart valve inflammation

caused by streptococcus pyogenes

what does clostridium tetani toxin cause

spores contaminate wound, germinate, release toxin on lysis

targets cells of spinal cord and brain stem

trismus (lockjaw) followed by general rigidity

death by interference with mechanisms of respiration

what is clostridium botulinum toxin

blocks transmission of nerve signals to muscles

antagonist of acetylcholine

treatment : antitoxin, ventilator

what is gangrene

death of soft tissue

clostridium perfringens grows in necrotic tissue

treatment - surgical removal

what are some bacteria that can cause upper GI tract infections

helicobacter pylori - stomach ulcer, cancer

what are some bacteria that can cause urinary tract infections

E. coli

staphylococcus saprophiticus

what are some sexually transmitted bacterial infections

chlamydia trachomatis

treponema pallidum

neisseria gonorrhoea