Medical microbiology practice questions for test 1

practice questions from canvas, mostly chap 2, and chatgpt

What is the correct term for the following description “incoluating some on with pustules material from pox scabs on someone with small pox symptoms for the purpose of providing immune protection.”

Variolation

what type of of pathogen has water as its primary source of exposure (exposure to contaminated water)?

Parasites

We are exposed to this type of pathogen the most because it is the most prevalent?

bacteria

an organism that can harbor and spread an infection but does not have symptoms is a…?

carrier

Development of the electron microscope allowed us to observe ____ for the first time

viruses

what were viruses first called?

filterable reagents

Variations in contagious properties of pathogens causes them to spread in different ways. If a pathogen spreads through air it is considered highly contagious. Which of the following is typically associated with aerosolization and respiratory transmission?

viruses

regarding the chain of infection medications are unlikely to block or limit…?

Our exposure to infectious agents

which pathogen can alter the host genome permanently and therefore is most likely to cause cancer?

viruses

what are examples of transforming viruses?

• HPV

• EPV

• Hepatitis

Which arm of the immune response can use barriers and responses that do not involve WBCs?

innate immunity

at early stages of germ theory invisible filterable agents were actually…

viruses

What are 4 standard bacteria targets for antibiotics?

1. Cell wall

2. Protein synthesis

3. Nucleic acid

4. Metabolism

what are 3 links to the chain of infection?

1. Exposure

2. Grows

3. Released back out into environment

which type of cell wall has phospholipids and therefore requires special transport molecules to move across the cell wall?

gram -

all of the following are a standard niche for commensal bacteria (bacteria flora) except:

• lungs

• Oral cavity

• CNS (spinal cord/brain)

• Skin

• GI tract

CNS (spinal cord/brain)

gram staining of bacteria is associated with?

staining the cell wall of bacteria

what will happen to most strains of bacteria if they are grown at 42 degrees C?

They die or their ability to grow is significantly reduced

true or false: all bacteria have the same shape

false

all of the following are anatomical structures of bacteria except…:

• cell wall

• Flagella

• Plasmids

• Nucleus

• Plasma membrane

nucleus

which of the following is not impacted by the anatomical difference between the gram - and gram + bacteria:

• ability to generate cellular energy (ATP)

• Ability to secrete intra-cellular bacterial components out of the bacteria

• Ability to absorb antibiotics

• Adhesion to surfaces

ability to generate cellular energy (ATP)

this structure is only found in gram (-) bacteria and not gram (+)?

LPS

true or false: the cell wall can impact is ability to colonize in niche and cause disease a therefore contributes to the virulence of a bacterium

true

true or false: antibiotics selection is a good way to screen for or identify certain types of bacteria

true

The repressor protein binding to the operator region (O) of the lac operon will…?

Block production of polycistronic RNA that will lead to the synthesis of enzymes to breakdown lactose

how can bacteria survive so well in poor nutrient settings?

• the use of genetic operons

• The use of polycistronic mRNA

• In some cases, the ability to form spores

• In some cases, the ability to generate their own glucose from O2

• In some cases, the ability to scavenge iron

which classification of bacteria would die in high oxygen growth settings but can thrive and produce toxic byproducts of fermentation in low oxygen growth settings?

Oligate (aka strict) anerobes

which of the 3 types of bacteria DNA exchange require a secondary infection from another type of microorganism?

transduction

true or false: mRNA in bacteria can encode multiple protein on a single RNA strand while mRNA in eukaryotes only encodes one protein

true

Which molecules regulate the lac operon?

• lactose

• Glucose

• Repressor

• CAMP (cyclic AMP)

• Cap protein

in the lac operon what is the effect of molecular binding to the operator (O) regulatory region of the genetic operon?

Enzymes will not be produced at all

toxic byproducts of fermentation will have the largest impact on which organ/tissue?

GI tract

which one of these is a primary contributor to the issue with antibiotic resistance being able to spread from one strain of bacteria to another?

The ease at which bacterial DNA can be exchanged

which types of DNA would you not find in bacteria?

mitochondrial DNA

An appropriate description for exposure is…

Source

An appropriate description for infection is…

route of exposure to enter host

An appropriate description for colonization is…

growth in host niche

true or false: once bacteria begin colonizing and aggregate in their host niche, they can change to improve their adhesive capabilities and reduce the host immune response against them all of which enhances their colonization capabilities.

True

for bacteria colonizing (growing) within a niche, list bacterial virulent factors that can cause chronic problems

exotoxins

• vaccinations DpT

Flagella

• trigger inflammation

Byproducts of fermentation

LPS

• trigger inflammation

true or false: differences in the cell wall are associated with variations in colonization in the host and help define the host niche for a particular bacterium

true

The best description for pseudomonas aeruginosa is…

Opportunistic lung infection

The best description for anthracis baccilus is…

Acute toxin exposure

The best description for listeria monocytogenes is…

can invade cells and spread though the body from cell to cell

The best description for salmonella typhi is…

classic food born illness and zoonistic transmission

Which pathogen listed below does not have exotoxins as a virulent factor for pathogenesis?:

• staphylococcus aureus

• Vibrio cholerae

• Anthracis baccilus

• Shigella dysenteriae

s. aureus

for acute exposure to bacteria (bacteria that does not colonize but can still cause pathology) what is the most common type of virulent factors that we have to be concerned about?

Byproducts of fermentation

gas gangrene is a rare but possible pathology due to bacteria infection and colonization. Which of the following below is strongly associated with gas gangrene?

production of toxic byproducts due to fermentation from colonization to anaerobic bacteria

of the following are associated immunopathology due to bacterial infection / colonization except…

• production of a super antigen exotoxin

• Fever

• Binding to and activation of TLR

• Production of toxic byproducts of bacterial fermentation

Production of toxic byproducts of bacterial fermentation

bacterial changes to improve adhesion and avoiding immunity (i.e. mucoid conversion or production of m. Protein) will have the highest impact on which of the following (best answer)?

• exposure

• Infection (invasion of microorganism into host)

• Colonization

Colonization

What is the target of beta-lactam antibiotics?

peptidoglycan synthesis (cell wall)

which target of antibiotics does not require the antibiotic to be transported through the antibiotic to be transported through the plasma membrane (AKA cytoplasmic membrane). Asked another way, which target is not intracellular?

Peptidoglycan

we base antibiotic spectrum largely on cell wall characteristics: gram (-) vs. gram (+) and cellular energy characteristics: strict aerobic vs. strict anaerobic. Which combination of bacterial categories listed below is likely to be most resistant (define narrowest of spectrum) to antibiotics?

Gram (-) and strict anaerobic

Beta-lactamases are enzymes that are produced by bacteria to resist (overcome) antibiotics. Which bacterial target is associated with the ability to become resistance to antibiotics by producing thee beta-lactamase enzymes?

peptidoglycan synthesis (cell wall)

which two antibiotics are beta-lactams?:

• penicillin’s (penicillin/ ampicillin/ carbenicillins/ methicillin)

• Cephalosporins

• Aminoglycosides

• Tetracyclins

• Rifampin

• Sulfonamide

• penicillin’s (penicillin/ ampicillin/ carbenicillins/ methicillin)

• Cephalosporins

There are two classes of antibiotics based on cell wall structure. Which class of bacteria that is most sensitive to beta-lactam antibiotics?

gram +

some antibiotics require active transport into the bacteria which requires cellular energy. These types of antibiotics are limited in spectrum and therefore are only effective against one main category of bacteria. Which type of bacteria are susceptible to these types of antibiotics? Hint: to understand this question you have to understand that active transport requires energy. Therefore, only bacteria that produce sufficient cellular energy are susceptible. Putting all this together, which bacteria produces. The largest amount of cellular energy is therefore susceptible.

strict (obligate) aerobes

Is gram + more or less sensitive to antibiotics?

More sensitive because the majority of the cell wall is made of peptidoglycan

Is gram - more or less sensitive to peptidoglycan?

Less sensitive because the cell wall has less peptidoglycan

which type of bacteria produces more ATP due to its use of oxygen for metabolism?

Aerobic bacteria

which type of bacteria is more likely to be susceptible to antibiotics that require active transport (ATP) for uptake?

aerobic bacteria

why do anaerobic bacteria typically have a reduced susceptibility to antibiotics that rely on active transport for uptake?

they lack ATP production for active transport

which metabolic pathway is involved in the synthesis of folic acid, an important factor in bacterial metabolism?

anaerobic fermentation (though, can be found in aerobic metabolism)

which bacteria are less likely to have a significant amount of peptidoglycan in their cell wall?

strict anaerobic bacteria

how do we categorize susceptibility to antibiotics based on cellular energy and cell wall characteristics?

by whether the bacteria are aerobic or anaerobic, and whether they are gram + or gram -

what does adhesion mean?

the ability to colonize

what happens when bacteria is symbiotic with the host?

mutually beneficial—nonpathogenic

• live in their niche: GI tract, skin, oral cavity, etc

• estimated: 100 billion bacteria living in and on our body

• occupies physical space on host tissue so “pathogenic” bacteria cannot adhere

where is bacteria found?

common on skin (particular moist areas), intestines, airways, oral cavity

if “bacterial flora” is killed or removed…

opportunistic infections can occur

antibiotics can kill bacteria flora and long-term use result…

in other bacteria (possible pathogenic) supplanting the bacterial flora

can commensal bacteria become pathogenic (conversion)?

mucoid conversion: periodontal disease

what happens when bacteria flora leaves it NICHE (why do we wash our hands)?

can cause infection in the area

What’s the importance of flora?

• occupies space on skin and can have antimicrobial properties

• provides energy that can be absorbed by GI tract and help with digestion by breaking down food that the GI tract cannot

• releases oils that keep that keeps one from drying out

how can we classify bacteria

• cell wall

  • gram +/ gram -

• shape (appearance under microscope)

• staining (appearance under microscope)

• serotyping

  • antibody detection

    • unique antigen— family, genus or species

• growth conditions

  • unique specific sequences

• ribotyping

  • subtle changes to 70s ribosome sequence detected by DNA sequencing

• plasmid profile

  • cytoplasmic plasmid DNA content

• metabolism

  • aerobic vs. anaerobic

what is the boundary of bacteria?

bacteria has a cell wall (unique to yeast and bacteria) that surrounds the plasma membrane

cell wall is either gram + or gram - based on staining

what are classifications of the cell wall for gram +?

• outerlayer of cell >50% peptidoglycan (high degree)

• SIMPLE, THICK, ADHESIVE PROPERTIES (minimal adhesions molecules)

• sticky and smooth surface with limited proteins (high amt of teichoic acid and peptidoglycan)

• retains crystal violet & gram iodine (purple)

• resists safranin red

• lysozyme sensitive

• flagellum

• teichoic acids (high degree)

what are classifications of the cell wall for gram -?

• outerlayer of cell wall ~10% peptidoglycan

• doesn’t retain crystal violet & gram iodine, PINK

• outermembrane (asymmetrical lipid uni-layer) & periplasmic space

• more complex phospholipids

• thin

• “minimal peptidoglycan”

• transmembrane protein

• surface proteins for cellular adhesions

• stained by safranin red

• lysozyme resistant

• flagellum

• LPS

• pilin

• periplasmic space in between 2 membranes

• pore proteins

what are similarities of the gram + / gram -?

• can contain flagella (for motility)

• have a typical in cytoplasmic membrane

what does the cell wall differences contribute?

• different adhesive properties when attaching to host cells

• different secretion methods

  • ex: secretion of bacterial toxins into host cells or transfer bacterial DNA into other cells

what is the gram-stain morphology of bacteria?

1. the crystal violet of gram stain is trapped in the thick peptidoglycan layer in gram-positive bacteria. the decolorizer cannot remove the crystal violet so GRAM POSITIVE is violet

2. the decolorizer washes the crystal violet from the thin layer peptidoglycan in gram negative. then the red counter stain makes gram-negative bacteria look pinkish

what is spirochete?

form sores by burrowing into tissue due to shape-contribute to virulence

what is coccus or coccobacillus?

aggregate and form biofilms to increase virulence

what is bacillus?

streamlined for flagellum movement and cilia (increased surface area)

what is vibrio bacteria?

aquatic bacteria: twitching motility uses vibration not cilia for flagella

what are common molecules that can activate immune responses and are involved in virulence?

• peptidoglycan surface structure — causes a slick/slimy

  • component that makes up a good portion of gram +

• capsule or slime layers — NO membrane surface antigens can avoid immune detection — common structure on gram +

• adhesions molecules —> in order for this to attach, it needs a chemical reaction… “trojan horse”

  • LPS — (TLR-4 activator): gram-negative only

  • pilin (LTR-2 activator): gram negative only

• secretion molecules: gram negative only

  • sex pili (f-pili)

    • commonly transfers DNA from bacteria to host cell or other bacterial

  • secretion systems (four types)

    • can secrete toxins and other virulent material from bacteria

what do blood samples detect?

needle extraction

• bacterial septicemia

• HIV

what is are fomites?

any objects or materials that allows bacteria to grow

what can you use to do clinical samples in the cerebral spinal fluid?

needle extraction

• detect spinal meningitis

what can you use to do clinical samples in the genital tissue?

swabs

• detects herpes, syphilis, HPV

• detects fungal infection

what do dermal swabs detect?

fungus

what can you use to do clinical samples in the oral cavity?

swabs

• detects streptococcus

what can you use to do clinical samples in the respiratory tract?

• sputum — collection of mucus

• bronchial lavage fluid (BAL)

• detects pseudomonas, fungus that can cause asthma

what can you use to do clinical samples in the urine?

specimen jar

• bacteria, parasites

what can you use to do clinical samples in the fecal material?

specimen jar

• bacteria, parasites

how to detect the presence of bacteria:

microscopy

• light microscope — fungus, bacteria, parasites

• electron microscopy - virus

antigen detection

• blood samples, sputum, BAL, urine

• measures the presence of pathogen antigens in blood

pathogen DNA detection

• PCR - amplification of known pathogen sequence

cultures

• measuring pathogens in biological samples collected from patient

pathogen antibody detection

• the presence of antibodies for specific pathogen antigen due to exposure

  • ex: HIV viral “gag” protien exposure will develop antibodies that can be measured in the blood

what are common synthesized molecules?

amino acids: for proteins

nucleotides: RNA and DNA

lipids: phospholipids and other fats

carbohydrates (sugars): used for energy storage and cell wall components

what is biosynthesis is important?

• cell wall and cytoplasmic membrane components, nucleic acids, protein components

• produce biological material involved interaction with host

  • virulence factors for bacteria that cause diseases

  • exotoxins, flagella, LPS, etc

• maintain turnover of cellular structures

  • cell wall reorganization

• bacterial replication

what is glycolysis?

breakdown of glucose into pyruvic acid

• pyruvic acid can be used for byproducts —> fermentation

what are classifications of bacteria by carbon source?

autotrophic bacteria: can generate essential elements from inorganic carbon source (CO2) and water (H2O) and use essential elements to produce cellular components (anabolism)

heterotrophic bacteria: require more complex organic carbon sources (polysaccharides, fatty acids, etc) to generate essential elements to produce cellular components

what are the classifications of bacteria by O2 exposure?

byproducts of metabolism using oxygen in bacteria

• **H2O2 and O2- —> these oxidative radicals that can be toxic if not disposed of

obligate anaerobes

• can only survive in the absence of O2

• cannot detoxify the byproducts of oxygen metabolism

  • H2O2 & O2-

• build-up of toxic products kills the bacteria

obligate aerobes

• need O2 to grow

  • have superoxidase dismutase and catalase to detoxify H2O2 and superoxide radicals

  • have ETC in plasma membrane for metabolism

  • DO NOT HAVE FERMENTATION capabilities

  • do not produce byproducts that can be toxic to host

facultative anaerobes

• can grow in the absence or presence of O2

what are strict aerobes?

• need O2

• only generate cellular energy by ETC in plasma membrane

• fermentation limited or absent

• typically DO NOT generate fermentation byproducts

  • if it has the possibility to ferment, it come w/ byproducts