Chapters 9, 24, 25 and 26

Endospores are called resting bodies because


they do not metabolize and are resistant to heating, various chemicals and many harsh enviromental conditions


Endospores are not for


reproduction.  They form when essential nutrients or water are not available.

Once an endospore forms in a cell


The cell will disintergrate


Endospores can remain dormant


for long periods of time



Endospores are impermeable to most stains, so _________________


heat is usually applied to drive the stain into the endospore.



Once stained, the endospores do not readily





Endospores are stained with what type of stain?



Schaeffer – Fulton stain



Most capsules are composed of


Polysaccharides, which are water soluble and uncharged



Because of the capsule’s NONIONIC nature,


simple stains will not adhere to it.



Most capsule staining techniques stain the bacteria and the background leaving the capsules



unstained – essentially a negative capsule stain.



When bacteria such as streptococcus pneumoniae have a capsule, the body’s white blood cells cannot



phagocytize the bacteria.


Many, bacteria are Motile, meaning  



They have the ability to move from one position to another in a direct manner.



Myoxybacteria move by exhibiting a


gliding motion



Spirochetes move by

undulating using axial filaments



_________________ can be stained after being carefully coated with mordant.




Flagella stain reagent contains


alum and tannic acid mordants and crystal violet stains



Flagella have two main types


Peritrichous (all around the bacterium)


polar (at one or both ends of the cell)



Motility can be determined by observing


hanging drop or wet mount preparations of unstained bacteria, flagella stains, or inoculation of soft (or semisolid) agar deeps.


Wide variety of chemicals called _______ are available for controlling the growth of microbes.


antimicrobial agents



These are chemical agents used on inanimate objects to lower the level of microbes




These are chemicals used on living tissue to decrease the number of microbes on their surfaces.




This causes the temporary inhibition of bacterial growth


Bacteriostatic agents



These agents cause bacterial death


Bacteriocidal Agents



No single chemical is the best to use in all situations.


Antimicrobial afents must be matched to specific organisms and enviromental conditions



Additional variables to consider in selecting an antimicrobial agent include


PH, solubility, toxicity, organic material present adn the cost.



The important criteria for evaluating the effectiveness of antimicrobial agents are


Their concentration, length of contact, whether it is lethal (cidal) or inhibiting (static)



Before a disinfectant is selected, the ___________ for the most common and persistent microbe identifies at a health facility should be determined


Decimal reduction time (DRT)



The DRT (Decimal reduction time) is the time it takes

to kill 90% of the test microbial population.



The standard method for measuring the effectiveness of a chemical agent is


The American Official Analytical Chemist’s

Use-dilution test



In the use-dilution test the effectiveness of a disinfectant can be determined by the



amount of resulting growth



The use-dilution test is limited to bactericidal compounds and cannot be used to evaluate


bacterial static compounds


The observation that some microbes inhibited the growth of others was made by





Pasteur observed that by


infecting an animal with pseduomonas aeruginosa protected the animal against bacillus antracis

_____________ is a substance produced by one microorganism that inihits other microorganism






_____________ produces nearly 70% of all antibiotics


Streptomeces bacteria



Antimicrobial drugs are used


internally whether natural (antibodies)

or synthetic.

To treat an infectious disease the doctor needs to


select the correct antimicrobial agent intelligently and administer the appropriate dose and follw that treatment to be aware of the resistant forms of teh organism that might occur

The clinical laboratory isolates the


pathogen (disease causing organism) from a clinical sample and determines its sensitivity to antimicrobial agents.

in a disk diffusion method,

petri plate containing an agar growth medium is


inoculated uniformly over its entire suface and paper disks impregnated with various antimicrobial afents are place on the suface of the agar.; An effective agent will inihit bacterial growth and measurements made of the ZONES OF INHIBITION around the disks.



The ___________________ of antibiotic is determined by testing for bacterial growth in dilutions of the antibiotic in nutrient broth


Minimum inhibitory concentration (MIC)



When inhibitions zones can be compared to a standard table, we then use the _____________ to determine susceptibility


disk diffusion method



The diameter of zones of inhibition is measured in milimeters and be the bacteria’s  __________, __________ and __________ to the agent being tested





Ampicillin is a __________ and its mode of action is



Semisynthetic Penicillin


Inhibits cell wall synthesis



Erythromycin is a __________ type of microbial agent and its mode of action is




Inhibits protein synthesiss

Penicillin G is a ______________ type of antimicrobial agent and its method of action is ___________.


B – Lactam


Inhibits cell wall synthesis

Streptomycin is a __________ type of antimicrobial agent

and its method of action is ____________. 




inhibits protein synthesis



Tetraycycline is  a ______________ type of antimicrobial afent and it method of action is ____________.




Inhibits protein synthesis



Ciproflaxin is a __________ type of antimicrobial agent and its method of action is ________

Vancomycin is a ____________ type of antimicrobial agent and its mode of action is ___________.





inhibits cell wall synthesis

Microorganisms that are more or less permanent are called


normal microbiata


Microbes that are only present for days or weeks are referred to as


Transient microbiata

He noted that aseptic methods ws directly related to the incidence of puerperal fever and other diseases.


Ignaz Semmelweis




Categories: Microbiology