Microbiology Final Exam Study Guide

1) crystal violet is applied to heat fixed smear 1 min. this stains all cells, called a primary stain. rinse w/ water 2) an iodine mordant is added; 1 min, rinse 3) wash with ethanol (some species of bacteria are decolorized and some are not. if smear retains purple dye, organism is gram positive. if alcohol removes the dye, organisms are no longer visible.) 4) safrinin is used as a counterstain. it is applied and the decolorized bacteria are visibly red. these are gram negative.
list the steps of a gram stain in order
gram positive-crystal violet and gram negative-safrinin. the gram stain reflects a basic difference in the cell wall structure of bacteria. it is the first step in identification and the susceptibility of miocroorganisms to antibiotics is often related to the gram reaction.
what are the two possible responses of a gram stain?
gram positive
will retain crystal violet dye and become purple. peptidoglycan layer is thick.has many teichoic acids. has no periplasmic space. has no outer membrane. has little to no LPS content. has low lipid and lipoprotein content because acid fast bacteria have lipids linked to peptidoglycan. has 2 flagellar rings in basal body. produces exotoxins. has very high resistant to physical disruption. has a high cellwall disruption by lysozyme. susceptible to penicillin and sulfonamide. not susceptible to streptomycin, chloramphenicol, and tetra cycline. highly inhibited by basic dyes.highly susceptible to anionic detergents. highly resistant to sodium azide. resistant to drying.
gram negative
can be decolorized to accept the counterstain safranin and stain pink/red.peptidoglycan layer is thin. has no teichoic acids. has periplasmic space. has outer membrane. has high LPS content. has high lipid and lipoprotein content because of the presence of the outer membrane. has 4 flagellar rings in basal body. produces endotoxins and exotoxins. has very low resistance to physical disruption. has a low cell wall disruption by lysozyme because it requires pretreatment to destabilize the outer membrane. not susceptible to penicillin and sulfonamide. susceptible to streptomycin, chloramphenicol, and tetra cycline. not inhibited by basic dyes. not susceptible to anionic detergents. susceptible to sodium azide. susceptible to drying.
scanning acoustic
what is the best microscope for biofilms?
transmission electron microscope. 10,000x-100,000x
which microscope has the highest magnification?
biofilms
microbial communities that reside in a matrix called slime made of hydrogel. enable bacteria to share nutrients and shelter them from drying and other harmful environmental factors. play an important role in the digestive system of ruminants. 70% of all human infections involve this. and these are 1,000 x more resistant to antibiotics than normal bacteria. pass around antibiotic resistance (DNA) through conjugation. they especially infect humans through nosocomical infections from indwelling medical devices like catheters and ventilators. everything has biofilms on it but it becomes dangerous and an infection when it gets inside the body
biofilms
pts with catheters are at risk because of what?
helminths
Nutritional type: Chemoheterotroph,ATP
Cellular Arrangement: Multicellulare, has tissues and organs
Food Acquisition Method: Ingestion/absorbtion
Charecteristic features: elaborate reproductive system; transmitted via ingestion.
latent viruses
HSV1 and HSV2(cold sores), HTLV1 and HTLV2(Luekemia), and Varicellovirus(shingles) are examples of this type of virus
persistent viruses
HIV1 and HIV2/AIDS, HPV(cervical cancer),measles(SSPE), HBV(Hepatitis B virus) are examples of this type of virus
the CAUSE of infectious disease. *important to note that not all diseases are caused by microoganisms therefore this method cannot be used to find the cause to all infectious diseases.*
Koch’s postulate is used to prove _______________
epidemiology
the study of WHERE and WHEN diseases occur and HOW they are transmitted. Center for Disease and Control (CDC) collects data and it is published in the Morbidity and Mortality Weekly
endemic
disease that is constantly present in a population(ex: common cold)
epidemic
disease acquired by many hosts in a given area in a short time(ex: Influenza).
pandemic
worldwide epidemic.(ex: AIDS, FLU H1-N1)
nosocomial infections
infections that are acquired as a result of hospital stay. Affect 5-15% of all hospital patients. In order for a nosocomial infection to develop, 3 things must be present:
1.)microorganisms in a hospital environment
2)compromised host
3)chain of transmission
cellulose
what is the major component of the plant cell wall?
chiton
what is the major component of the fungi cell wall?
peptidoglycan. ***note: pseudomurein for archaea****
what is the major component of the bacterial cell wall?
NAG and NAM
what is peptidoglycan made of?
mycobacterium
has a thick waxy wall
mycoplasma
has no cell wall
no cell wall
animal cells and protozoa have __________
mesophile
most common bug to cause food spoilage in terms of temperature. 10-50 degrees Celsius. room temp
psychrophiles
-10-20 degrees celsius
pyschrotrophs
0-30 degrees celsius
thermophiles
40-70 degrees celsius
hyperthermophiles
67-110 degreees celsius
mycoplasmas. because they have no cell wall
what group would you expect penicillin to be uneffective against?
1,000x more resistant to microbicides. 70% of human infections associated with biofilms
biofilms are _____________
gram positive. no porin protein like gram negative has. penicillins prevent the cross-linking of the peptidoglycans, which interferes with the final stages of the construction of the cell walls.
which cell wall is sensitive to penicillin?
viruses are not cells; bacteria are. bacteria are treated with antibiotics; viruses arent. viruses are obligate intracellular and they have DNA or RNA but never both and they all have a protein coat that surrounds the nucleic acid-capsid.
what is the difference between bacteria and viruses?
enveloped viruses
contain and envelope around the outside of the genetic material and the capsid. ex. influenza
polyhedral viruses
virus structure that contains capsomere, Nucleic acid, and capsid and lack envelope.
complex viruses
virus structure with a virion, and in addition having feet like apparatus to help inject its genetic material into the host cell. has spikes for attachment
helical viruses
virus structure that contains a cylindrical capsid with helical/spiral genetic information
most particles of some viruses do not induce cancer. Don’t develop until long after the viral infection. Cancers do not seem to be contagious and viral diseases usually are.
why are cancers hard to link to viruses?
subclinical
viruses that infect without causing symptoms
lysogenic cycle
virus cylce where virus infecs host and does not destroy cell when released
exotoxin
Source: Mostly Gram +
Relation to Microbe: by products of growing cell
Chemistry: Protein
Fever: NO
Neutralized by Antitoxin: YES
LD50: small
endotoxin
Source: Gram –
Relations to Microbe: outer membrane
Chemistry: Lipid A and LPS
Fever: YES
Neutralized by Antitoxin: NO
LD50: Relatively Large
****role: cause DECREASED BP*****
siderophore
take iron from host cells. Protein that bacteria release that can bind to iron and take it away(compete w/ tranferin iron complex[keeps iron for you] )
innate immunity
defenses we are born w/;rapid; always there
lytic cycle
virus cycle that ends with the death of the host cell as the virus is released
Attachment(Lytic Cycle)
stage of cycle wherre phage attaches(chance collision)by tail fibers to host cell
Penetration(Lytic Cycle)
stage of cycle where phage lysozyme opens cell wall; tail sheath contracts to force tail core and DNA into cell.
Biosynthesis(Lytic Cycle)
stage of cycle where there is production of phage DNA and proteins using the host cell’s ribosomes, enzymes, and amino acids.
Maturation(Lytic Cycle)
stage where assembly of phage particles takes place
Release(Lytic Cycle)
stage where phage Lysozyme breaks cell wall
incidence
fraction of a population that contracts a disease DURING A SPECIFIC TIME.
symptoms
change in body fxn that is felt by a patient as a result of a disease(subjective)(what patients tell you)ex: pain and malaise
signs
a change in a body that can be measured or observed as a result of disease (objective) ex: fever, rash, swelling, paralysis.
neutrophils
which WBC has the highest phagocytic activity?
eosinophils
which WBC is associated with parasites?
fungi
Nutritional Type: Chemoheterotrophic
Cellular arrangement: unicellular, multicellular, filamentous, fleshy
Charecteristics: Fungi are classified according to sexual and asexual spores. Fungi grow in HIGH osmotic pressure, LOW pH, and LOW moisture environments.
human pathogens: YES
Food source: Organic
diapedesis
Phagocytes squeeze between endothelial cells
margination
Phagocytes stick to endothelium
pseudomonales
Order of bacteria that has efflux pumps, Responsible for 10% of Nosocomial infections. on soil and plants. cystic fibrosis patients are susceptible to this.
it is a bacteria that is stalked for increased nutrient absorption. occurs in low nutrient environments such as lakes.
what is unusual about caulobacter?
candida albicans
what are yeast infections caused by?
direct aggultination
antigens on a cell(ex:blood typing)
attenuated whole agent vaccine
use living organism but weakened microbes; provides long lasting lifetime immunity derived from mutations accumulated during long term artificial culture; not recommended for patients with weakened immune systems(ex: measles, mumps, rubella, chickenpox)
inactivated whole agent vaccine
uses microbes that have been killed, usually by Formalin or Phenol. (ex: rabies, influenza, and salk polio)
sub unit vaccine
use only those antigenic fragments of a microorganism that best stimulates an immune response; inherintly safer because they cannot reproduce in the recipient; fewer side effects(B. Pertussis)
recombinant vaccine
used in new Hep B.; consists of a portion of the viral protein coat that is produced by genetically modified yeast.
conjugated vaccine
developed in recent years to deal with the poor immune responses of children to vaccines. based on capsular polysaccharides. These are combined with toxoid leading to a very successful vaccine such as H Flu Type B even at 2 mnths.
nucleic acid vaccine
this vaccine Uses DNA insterted into plasmids
agglutination
particular antigens
precipitation
soluble antigens
mediators
cause the unpleasant and damaging effects of an allergic reaction(histamine,leukotrienes, and prostaglandin)
histamine
mediator that causes swelling, mucous secretion, tightening of airway, increase of permeability of blood capillaries
prostaglandin
mediator; effect is the longest and takes longest to release
leukotrienes
mediator; longer reacting; slower to happen
degranulation
process that releases mediators; mast cells and basophils undergo this.
anaphylactic reactions type 1
-occur within 2-30 min after re exposure to antigen
-can be systemic or localized
-IgE attached to Mast cells and Basophiles
-Antigen binds to two adjacent IgE
-Mast cell and basophils undergo degranulation which release mediators(histamine,leukotrienes,and prostaglandin)
cytotoxic reactions type 2
reactions that are directed against antigens located on cell tissue surfaces. Involve IgG and IgM antibodies and complement. Complement activation cause cell lysis or damage by macrophages.(ex: blood typing)
immune complex reactions type 3
these reactions involve antibodies against soluble antigens circulating in the serum. Antigen AB complexes can be deposited in organs and cause damage. IgG antibodies and antigens form immune complexes-circulate in the blood-pass between endothelial cells of blood vessels and become lodged in basement membranes. Here they activate complement and may cause transient inflammatory reaction(ex: glomurulonephritis)
cell mediated reactions type 4
involves cell-mediated immune responses. Delayed type hypersensitivities(DTH) due to T cells, not apparent for a day or more. Cytokines attract macrophages and t-cells(initiate tissue damage ex: transplant rejection, TB skin test, allergic contact dermatitis)
desensitization
objective is to cause the production of IgG using INJECTIONS of ANTIGENS rather than IgE-hoping that the circulating IgG Abs will act as blocking Abs.
part of the penicillin is produced by the mold and part is added synthetically. Nucleus is the natural part. side chains are synthetic.
what is the difference between natural penicillins and semisynthetic?
jock itch
tine cruris
amphrotercerin B and Griseofulvin(both are types of Polyenes)
list some antifungal drugs
toxoplasmosis, cytomegalovirus, and syphilis
what are the diseases that cross the placenta?
metronidazole
whats the treatment for bacterial vaginosis and trichinosis?
gonorrhea
most common reportable disease in US
rickettsia has an insect vector.
major difference between rickettsias and chlamydias
cysticerci
encysted larvae of tapeworms
chloramphenicol
binds to 50s portion of ribosome and inhibits formation of peptide bond(amino acids)*side affect: it can suppess bone marrow leading to aplastic anemia; potentially fatal* -also macrolides
streptomycin
changes shape of 30s portion of ribosome, causing code on mRNA to be read incorrectly. -aminoglycosides
tetracycline
(broad spectrum) interefere with attachment of tRNA to mRNA-ribosome complex which prevents the addition of amino acids to the growing protein chain. **serious side effect: cannot be used on children because it turn teeth brown. cannot be used on pregnant women because it can cause liver damage.**
cephalosporins 1st
generation of cephalosporins; narrow spectrum, gram+
cephalosporins 2nd
generation of cephalosporins; extended spectrum includes gram-
cephalosporins 3rd
generation of cephalosporins; includes pseudomondales;injected; also oral
cephalosporins 4th
generation of cephalosporins; injections, but have the most extended spectrum
bacitracin
inhibits cell wall formation earlier than Penicillin. Against gram+(staph and strept)
vancomycin
very important antibiotic. should be used as a last resort against MRSA. IV administered only. known as “The Big Boy”.*VRE is considered a medical emergency.*
cephalosporins
inhibit cell wall synthesis; consists of 4 generations. have beta lactam ring like penicillin which inhibits the replication of bacterial cell walls.
penicillins
all have beta lactum ring called the nucleus. A group of over 50 related chemicals. they differ by the side chains of the nucleus and prevent crosslinking of peptidoglycan of gram +. inhibits cell wall synthesis.
macrolides
the newest class of antibiotics. it binds to the 50s subunit which prevents translation by blocking the tunnel of the ribosome. best known is Erythromycin, but also includes azithromycin(which has the highest levels of resistance from overuse).
aminoglycosides
broad spectrum, interferes with protein synthesis by changing the 30s subunit causing mRNA to be read incorrectly.**serious side effect: causes permanent damage to auditory nerve(ototoxic) and damage to kidney(nephrotoxic)**
rifampin
inhibits mRNA synthesis. used in combo to treat tuberculosis. **serious side effect: turns saliva, urine, tears, sweat and feces orange.**
polymixin B
topical application. treats gram(-) and is available over the counter. causes injury to the plasma membrane.
quinolones and flouroquinolones
hese inhibit DNA gyrase activity. Drug of choice to treat urinary tract infections. common drugs on the market: Gatifloxacin, Gemifloxalin, moxifloxin & Ciprofloxcin. ***Cipro most common one used for UTI’s & anthrax.
antihelminth drugs
Niclosamide – prevents ATP generation. used to treat tapeworms.
Mebendazole – inhibits nutrient absorption in most intestinal
worms.
what type of drugs are these?
structurally & functionally similar to human cells, therefore hard to treat since medication can affect host.
why are helminthic diseases hard to treat?
70s
oxazolidinones(zyvox) prevents the formation of this ribosome?
30s
when altered this ribosome prohibits translation
50s
when altered this ribosome inhibits formation of peptide bond