MICROBIOLOGY - PORTAGE MODULE 5 PATHOGENIC MICROBES EXAM QUESTIONS WITH COMPLETE SOLUTIONS VERIFIED GRADED A+
When must universal precautions be taken?
When an unknown biological sample arrives in the lab for assessment and further characterization
Define the practice of universal precaution...
When must universal precautions be taken?
When an unknown biological sample arrives in the lab for assessment and further
characterization
Define the practice of universal precautions.
The practice of universal precautions means any and all samples, whether known or
unknown, are to be treated as potentially hazardous (or pathogenic) materials.
What must you use when you are practicing universal precautions?
The appropriate personal protective equipment (PPE) should always be used.
When assessing an unknown sample, several basic yet essential observations
can be made in addition to what?
the differential techniques described in Module 4.
List 6 things that a lab researcher should be certain to note during the process of
analyzing a microbial sample.
(1) the morphological characteristics (size and shape)
(2) the presence of any observable motility when viewed under a microscope
(3) capture images of any of the characteristics described above or draw the
observations.
Once differential testing has concluded, one should also document
(4) whether or not the organism was Gram-positive or Gram-negative
(5) the presence of any chemical reactions such as gas production (bubbling),
fermentation, etc.
(6) any distinct changes in color localized to the organism itself or its surrounding media
(e.g.) staph aureus on MSA agar.
,Properly documenting these observations significantly aids trained professionals
to identify what?
The causative agent and select the appropriate treatments against a foreign microbe.
Describe Streptococcus
Gram positive
Round bacteria that tend to link together in chain-like structures.
catalase negative
What is the definition of catalase negative?
The bacteria cannot breakdown peroxides
What type of plate is Streptococcus usually cultured on?
blood agar plates (BAP)
As there are numerous subtypes of streptococcus what is the quickest way to
identify and classify a potential streptococcus microbe?
Culture it on BAP and identify and classify a potential streptococcus microbe based on
its hemolytic properties.
Streptococcus, when grown on blood agar, can be what three types of
hemolysis?
alpha, beta or gamma
Describe alpha-hemolysis
Alpha-hemolysis presents as a greenish-brown discoloration surrounding the bacterial
colony, the result of the partial decomposition of hemoglobin found within blood cells.
Alpha hemolysis is characteristic of what type of Streptococcus?
Streptococcus pneumonia
Describe beta-hemolysis
Beta-hemolysis is classified as the capacity of a microbe to completely lyse red blood
cells. The resulting lysis presents as a distinct zone of clearing around the growing
colony.
Beta-hemolysis is characteristic of what 2 types of bacteria?
Streptococcus pyogenes
some strains of Staphylococcus aureus.
Describe gamma-hemolysis
, Gamma-hemolysis designates the absence or lack of hemolytic activity and the
resulting colonies are often white/tan in color growing on the red background color of
the unaffected blood agar plate.
Gamma hemolysis is a characteristic of what type of bacteria?
Enterococcus faecalis.
Beta-hemolytic Streptococcus can be divided into antigenic groups known as
what?
Lancefield groupings
All bacteria within the Lancefield groupings are what 2 things?
While all bacteria within this system are catalase-negative and coagulase-negative.
Where is the distinction in Lancefield groupings?
The distinction lies in the carbohydrate composition of bacterial antigens located in the
cell wall.
Grouped based on similarities, each Lancefield grouping is designated by what
and give 3 examples?
a single letter such as
Group A, Group B, Group C
Streptococcus pyogenes belongs in which Lancefield grouping?
Group A
Streptococcus pyogenes is the causative agent behind what?
>90% of human streptococcal infections resulting in pharyngitis, scarlet fever or
rheumatic fever.
The genus Streptococcus contains what?
numerous disease-causing species
Streptococcal pharyngitis is also known as what?
strep throat
Streptococcal pharyngitis is in which Lancefield grouping?
Group A
Streptococcal pharyngitis (strep throat) is a disease characterized by what
symptoms?
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