Exam 2: Staphylococci
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enzymes that can lyse red blood cells
hemolysins
for bacteria that can secrete hyemolysins
Blood hemolysis plating
inhibits fungal growth
cycloheximide
inhibits peptidoglycan synthesis
LB
mimic D-ala-D-ala
LB+penicillin+cycloheximide
what happens when we are infected with the flu?
• flu penetrates airway epithelium • “send help” –> CD8+ T cell • cytotoxic response (killing infected cells) • decrease phagocytes antimicrobial function • decrease phagocytosis • decrease ROS production • increase susceptibility to bacterial infection
what happened during the 1918 spanish flu H1N1?
• 50% of the world was infected • 40-50 million died • even healthy young adults died • 95% actually died from bacterial pneumonia (secondary ico-infection)
how does the flu infect humans and how does it work?
• endocytosis • membrane engulfs flu cell • forms endosome (has H+, hydrolytic enzymes, flu cell) • virus RNA replicate and go into host cell
• help degrade H and N proteins * help with viral-endosomal membrane fusion
staph proteases
what does the epidermis consist of?
• keratinocytes • hair • basal layer • Dendritic cells • CD8+
what does the dermis consist of?
• SALT - lymph blood vessels
where does bacteria most likely grow in the skin?
most likely grow by hair follicle
what defenses does the skin provide against bacteria?
• hard to penetrate • slough off; hard to adhere • dry, low pH • antimicrobial fatty acids • dendritic cells • CD8 T cells • SALT
what kind of dendritic cells are on the skin?
Langerhans cells (antigen presentation)
skin associated lymphoid tissue
SALT
how do we also prevent bacterial penetration on our skin?
• handwashing - skin microbiota
how do our skin microbiota protect us?
occupy a nutrient niche and secrete antimicrobial compounds
how can bacteria be classified?
• gram staining (+/-. shape/size) • O2 requirement • salt • temperature • pH • nutritional (autotroph/heterotroph, etc)
what are the two types of positive bacteria from gram staining?
rod shape and cocci
what are the rod shape bacteria?
• Listeria - clostridium bacillus
what are the divisions of cocci bacteria?
*they can either be catalase + (bubbles) or catalase - (H2O2–> O2 + H2O)
if a coccus bacteria is catalase +, what kind of bacteria is it?
Staphyloccocus
if a coccus bacteria is catalase -, what kind of bacteria is it?
streptococcus
what are the divisions of staphylococcus?
coagulase + (clot) and coagulase -