lab test review from labs.. Flashcards
(41 cards)
Group A streptococci cause what
(S. pyogenes) pharyngitis, skin infections
Group B streptococci cause what
(S. agalactaie) colonize in genital tract.. cause neonatal meningitis and sepsis
Group D strepptococci..
(Enterococcus faecalis and enterococcus faecium, non enterococci) memebers of normal flora as long as in colon, can leave and cause urinary, biliary and cardio infections
a hemolytic
shows up green, partial hemolysis
b hemolytic
shows up clear, complete hemolysis. Production of hemolysin enzymes called streptolysin S and O
y hemolytic
no hemolysis, no space
Plasmids and Bacteriophages. Virulence genes.
plasmids and bacteriophages= extra chromosomal DNA elements that replicate independent of genomic DNA, allow exchange between strains and types of bacteria
Plasmids contain Virulence genes= which encode toxins, enzymes, etc that help bacteria overwhelm host tissues and immunity and obtain nutrients (ex staphylococcal toxins hemolysin and fibrinolysis) plasmids also carry genes that effect resistance to antimicrobials
Bacterial growth curve
Lag (vigorus metabolic activity but no divide), Log ( rapid cell division), Stationary (nutrient depletion or toxic products slow growth), Death (decline in number of viable bacteria)
bacteria adapt to their enviornment by ???
controlling gene expression (most common = changing amount of mRNA transcription)
Bacteria cell division
- elongation and dna replication 2. cell wall and plasma membrane divide, formation of septum 3. cross wall form around divided DNA 4. seperation
bacterial enzyme- Catalase
WBC produce h202 to kill bacteria, bacteria produce cataalse which converts h202 to water and 02 (subvert immune cells)
bacterial enzyme- Coagulase
forms clot around bacteria to protect it from immune cell ** pathogenic staphylococcus have this but non path don’t
Gram pos vs gram neg membrane components
Pos= has techtoic acid
neg= outer membrane, periplasmic space, etc
Cytoplasmic membrane ( plasma memebrane)
primary bacteria cell membrane, phospholipids (70% of membrane mass), has proteins ( selective perm, electron transport, oxidative phosphoralization, excretion hydrolytic exoenzymes, enzymes, receptors etc)
what chemical used to do gram staining test
crystal-violet
facultative anaerobes
with or without 02 ex. E coli. (normal gut, pathogenic otherwise cause uti or wound infection)
obligate anaerobes
need 02 (aerobic metabolsim). ex. staphylococcus epidermis
Anerobes
no 02. most vaginal and gut flora. ex gardinella vaginalis
cocci
small spheres
3 cocci subtypes
diplococci (2), stretococci (strips), staphylococci ( grapes)
bacilli
pills
spirochetes
worms
bacteria
smaller than one um ( except bacillus anthracis)… most abundant and tolerant organisims
prokaryotes (bacteria)
no neuc, genomic DNA single chromosome, plsmids, t&T carrried out from genomic DNA, protective think cell wall and lipid layers
