microbio lab exam 2 uiowa

colonization factors

proteins that allow bacteria to colonize in a certain part of the body

fibrin

Makes shield around bacteria preventing phagocytosis

virulence factor

biofilms

communities of bacteria that take in and share nutrients

play a role in chronic infections

Virulence factor

biofilm immune response blockers

requires adhesion and colonization proteins

examples of biofilms

dental plaque on teeth or algae in swimming pools

hemolysis

lyse red blood cells

toxins

bacteria that release poisons and destroy tissue

c. diff uses which toxins

toxin a and b

m proteins

similar to host cell proteins which help bacteria evade phagocytosis

coagulases

enzyme that produces fibrin from fibrinogen at the site of infection; clot offers protection from phagocytosis

coagulases can be identified by

clumping on tests

capsule

glycocalyx that surrounds the bacteria cell and prevents phagocytosis

DNAse

lyses DNA, allows DNA to escape neutrophils spit out DNA nets

positive DNAse test will look like

a clear zone around a streak of bacteria (yellow overtakes the agar)

where do you need to look for hemolysis?

isolated colonies

leukocydins

lyse white blood cells

gamma hemolysis

no change around isolated colonies

alpha hemolysis

brown or green coloring around colonies, but not a full lyse

beta hemolysis

complete lysis of RBCs which leaves a yellow hue

plasma

liquid portion of blood

white blood cells

involved in immune health

platelets

involved in blood clotting

red blood cells

involved in carrying oxygen

when would a white blood count indicate infection

greater than 10,000/μl

plasma %

55%

red blood cell %

45%

neutrophils

eat bacteria; high numbers indicate local bacterial infection

neutrophil looks

multi lobe

lymphocytes

T and B cells; high numbers suggest intracellular viral infection and low numbers indicate HIV

lymphocyte looks

unilobe

eosinophils

high numbers indicate allergic reactions or parasitic infections

eosinophil looks

horseshoe with some granules

basophil looks

thick nucleous very grainy

ABO stand for

sugar molecules on RBC surfaces

should you give a patient an antigen that they don't already have?

no

a blood specs

has a antigens, has anti-b antibodies, can receive a or o blood

b blood specs

has b antigens, has anti-a antigens, can receive b or o blood

ab blood specs

has a and b antigens, has no antibodies, can have any blood

o blood specs

has no antigens, has a and b antibodies, can receive only o blood

universal donor

type o- blood

universal receiver

type ab+ blood

how is blood type determined?

anti-sera testing will cause antibody-mediated crosslinking of cells and agglutination

clumping in a blood test shows

antigens present

if someone has the D antigen they will be what?

Rh positive

is Rh factor natural?

no, you develop IgG after first exposure

is Rh factor genetically determined?

yes, DD is dominant

fetal-maternal incompatibility

the mother's Rh status does not match the baby's so mom produces antibodies against baby

are a and b antibodies natural?

yes, they are IgMs

can Rh + patients receive Rh - blood

yes

PCR

test for the presence or absence of a gene using restriction enzyme or endonuclease

DNA fingerprinting

comparing the difference of isolates which tells us if its from the same source or not

primers for PCR

each products requires two individual primers using restriction enzyme or endonuclease

mecA gene presence means

methicillin resistance

DNA fingerprinting (PFGE) commonly used for

common sourcing

catalase negative means

strep

catalase postive means

staph

coagulase positive means

staph aureus

coagulase negative means

other staph

kirby bauer assay

tests for antibiotic sensitivities

alpha hemolysis optochin sensitive means

strep pneumoniae

alpha hemolysis optochin resistant means

viridans strep

beta hemolysis group a means

group a strep; pyogenes

beta hemolysis group b means

group b strep; newborns

gamma hemolysis means

enterococcus

selective media

prevents some type of bacteria from growing

differential media

distinguishes bacteria by using some visual marker; does not inhibit growth

MSA (mannitol salt agar) type of media

both: selects for salt, but differentiates mannitol fermentors

MacConkey Agar type of media

both: selects for gram negatives, but differentiates lactose fermentors

in which quadrant can you find transient bacteria?

first quadrant

in which quadrant can you find normal flora?

quad 2, 3, and 4

bubbles on a catalase test means

presence of catalase, positive test

a coagulase-positive test will present with what?

agglutination (clumps)

pathogens contain many

antigens

antigens

specific components of a pathogen that are recognized by your immune system

antibodies

recognize and bind to antigens

how do antibodies bind?

the epitope (nucleotide sequence)

good reasons to use an ELISA

- pathogen cannot grow on a plate

- an asymptomatic disease

- sensing antibodies from a previous illness

direct ELISA

detecting a pathogen (is this antigen currently in your body?)

indirect ELISA

detecting antibodies (did you form these from having an illness?)

further test for positive ELISA HIV screening

PFGE or Western Blot

strep pyogenes causes

strep throat, scarlet fever, rheumatic fever

a positive strep test will show

a line on the test section; give antibiotics

strep pyogenes is sensitive to what?

bacitracin

first step of a blood culture

identify the bacterial pathogen

primary medias for identifying pathogens

sheep blood, macconkey, chocolate, TSA

fastidious organisms

those that require many growth factors (chocolate)

identifying E. coli

gram-negative, + lactose fermentor

identifying pseudomonas

gram-negative, non lactose fermentor, blue fluorescent pigment with fruity odor

identifying proteus

gram-negative, non lactose fermentor, oxidase negative, swarming positive

identifying staph aureus

gram-positive, catalase positive, coagulase-positive

identifying strep pyogenes

gram positive, catalase negative, beta hemolysis, group a +

identifying enterococcus

gram- positive, catalase-negative, gamma hemolysis

for stool cultures non lactose fermenting is ...

BAD

hektoen enteric agar type of media

both: selective for gram negative rods, but differentiates lactose fermentors

non lactose fermentors differential in HTA

shigella is pale green while salmonella is black centered

blood agar media type

just differential

TSA agar type of media

none, grows everything

parasitic infection generally manifest as

gastrointestinal infections

What is the purpose of a hemolysis test

to look for lysis of Red Blood Cells

community MRSA

Mec A gene present

Pvl gene present

give antibiotics other than vancomycin