Microbiology Final Exam

The maximum growth rate within a bacterial population occurs during the ___________ phase of the bacterial growth cycle.

Log

In which growth phase are a population of bacteria most susceptible to being killed by antibiotic medications?

Log

Bacteria are classified in the kingdom:

Monera

Binary fission:

Is more efficient than eukaryotic cell division

The most common primary food source for bacteria is:

Carbohydrates

True or False: Most bacteria have only one chromosome.

TRUE

An extrachromosomal pice of DNA that replicates independently within a bacterium is called a ________________.

Plasmid

The generation time for bacteria X is 2 hours.

If you start with 1 bacteria X, given ideal growth conditions, in 4 hours you will have ______ bacteria X.

4

(@ 0 hours = 1 , @ 2 hours = 2 , @ 4 hours = 4

Most bacteria:

contain cell walls

An obligate pathogen of mammals is most likey to be a:

mesophile

A facultative anaerobe:

will grow in the presence or absence of free oxygen

True or false: A commensal organism can become an opportunistic pathogen under certain circumstances.

TRUE

Two daughter cells:

are genetically identical to each other, and to their parent cell

When viewing an agar plate innoculated with bacteria, a small circular patch of bacterial clones descended from a single cell are called a:

colony

LPS, the phospholipid component of some bacteria that causes endotoxic shock in patients, is found in:

gram negative bacteria

Some bacteria have _______________, which can increase their pathogenicity in two ways: 1. they can prevent or slow phagocytosis, making it harder for immune system to eliminate and easier for an infection to become established, and 2. they can make disinfectants less effective, increasing transmission of disease between patients.

capsules

Viruses are:

acellular

The protein coat surrounding the genome of a virus is called the

capsid

The viral genome can consist of:

RNA or DNA

A viral infection that is in a latent stage is:

undergoing a lysogenic replication cycle

Why are viruses considered obligate intracellular pathogens?

Because they require a specific host to replicate and reproduce.

True or false: Viruses are smaller than bacteria.

TRUE

True or false: Viruses do not typically exhibit host specificity.

FALSE

A bacteriophage is:

a virus that infects a bacteria

Retroviruses are unique in that reverse transcriptase allows them to create:

DNA from RNA

Prions are susceptible to destruction via which of the following methods?

None of the listed options are reliable methods of destruction

Which of the following immunoglobulin isotypes is found within mucosal surfaces?

IgA

Which of the following is NOT an example of a secondary immunodeficiency?

all of the examples listed are of patients with secondary immunodeficiencies

True or false: Most cases of immune-mediated disease can be linked to the recent administration of one or more vaccines.

FALSE

The humoral response works well against [A] pathogens, while the cell-mediated response is more effective for [B] pathogens

A = extracellular

B = intracellular

Which of the following is an example of adaptive immunity?

antibody production

Which of the following are capable of memory responses?

BOTH cell-mediated and humoral immune response

The portion of an antigen that an antibody recognizes and binds to is called the _____________.

epitope

Passive immunity is:

Humoral

Match the component of the immune system to its definition: Chemoattractant

Chemical compound released from damaged or dying cells, which will attract cells of the immune system to migrate in that direction

Match the component of the immune system to its definition: complement

Plasma proteins that play multiple roles in stimulating and regulating the immune system response

Match the component of the immune system to its definition: Membrane Attack Complex (MAC)

A channel or hole created in the cell wall of a bacteria, thereby killing it, as a result of activation of the complement system

Match the component of the immune system to its definition: Macrophage

A type of white blood cell that is both a phagocyte, and an antigen-presenting cell.

Match the component of the immune system to its definition: Lysosome

A membrane-bound organelle in eukaryotic cells, that contains enzymes that are capable of killing bacteria.

Match the component of the immune system to its definition: B-lymphocytes

B lymphocytes that have been stimulated to produce a specific antibody to a specific antigen

Match the component of the immune system to its definition: Helper T cell

A type of white blood cell that contributes to cell-mediated immunity by producing cytokines that stimulate cytotoxic T-cells and macrophages.

Match the component of the immune system to its definition: MHC-I

Molecules that most host cells use to present antigens on their cell surface, so that other cells of the immune system will notice and recognize them.

Match the component of the immune system to its definition: MHC-II

Molecules that B-lymphocytes use to present antigens on their cell surface, so that other cells of the immune system will notice and recognize them

Match the component of the immune system to its definition: PAMP

Patterns of molecules that are commonly found on the surface of a wide number of pathogens, which allow the immune system to recognize the pathogen as foreign.

Match the component of the immune system to its definition: Plasma Cell

B lymphocytes that have been stimulated to produce a specific antibody to a specific antigen.

Match the component of the immune system to its definition: Cytotoxic T cell

Lymphocytic cells that bind to antigens presented by infected host cells and directly kill the host cell (and with it the pathogen inside).

1. When, in the course of an infection, does the prodromal stage occur?

2.List two reasons why it can be difficult to accurately diagnose a patient that presents in the prodromal stage of an infection.

Occurs after the incubation period, before the acute phase

_______________________________________________________

The host having non-specific symptoms that can be similar to many different infections.

The prodromal stage may not provide enough clear evidence to make an accurate diagnosis at that point.

Both IN and parenteral (SQ) vaccines are available for Bordetella. When given as a sole vaccine, parenteral (SQ) vaccines will primarily result in [A] antibody production, while IN vaccines will primarily result in [B] antibody production.

A = IgG

B = IgA

Vaccines containing adjuvant are typically:

killed vaccines

The type of vaccine that should definitely be avoided in pregnant or immunocompromised patients:

modified live vaccines

Compared to a killed vaccine, why might a modified live or recombinent vaccine generate a more effective immune response against a virus such as Canine Distemper Virus or Feline Panleukopenia?

A modified live or recombinant vaccine is often more effective than a killed vaccine because it replicates in the host, closely mimicking a natural infection. This stimulates both stronger and more sustained immune responses, activating both humoral and cell-mediated immunity and leading to better immune memory. Killed vaccines do not replicate, resulting in a less robust and shorter-lived immune response.

Some people elect to measure their pet's titer to a certain disease, rather than automatically re-vaccinating when they are due. A vaccinal titer is more likely to [A] the patient's immune response to a disease, because it only measures the [B] portion of the response.

A =underestimate

B = humoral

You are seeing tech appointments while the Dr is in surgery. About 30 seconds after you administer a vaccine to a dog, he collapses on the floor with white MM and non-palpable pulses.

You rush him back to treatment, calling for help as you go. Which of the following drugs is critical to get into the patient immediately?

Epinephrine

How are you going to administer this dose of drug?

IM

True or false: The reason the number of bacteria plateaus during the stationary phase, is because cell division is no longer occuring.

FALSE

An anaphylactic vaccine reaction is an example of which type of hypersensitivity reaction?

Type I

The atopic response primarily involves which of the following?

IgE

Which of the following is true about staphylococcal infections?

They are typically commensal organisms that become opportunistic pathogens

Which of the following is true about streptococcal infections?

They vary by species - some are opportunistic pathogens, and others are frank pathogens

Which of the following is true about enterococcal infections?

They are typically commensal organisms that become opportunistic pathogens

The "catalase test" checks for the presence of an enzyme that converts H2O2 to oxygen and water.

Which is true about the catalase test?

Staphylococci are typically positive, and streptococci are typically negative

Which of the following tests is usually done to help differentiate among different species of staphylococci?

coagulase test

Staphyloccocal infections are typically suppurative, meaning that this type of cell is usually found at the site of infection, alongside the bacteria: ___________

neutrophil phagocytosing bacteria

Pathogenic strains of streptococci tend to exhibit which form of hemolysis, when grown on blood agar plates?

Beta

In what body tissue/location do enterocci typically reside?

gastrointestinal tract/feces

In what body tissue/location does Actinomyces typically reside?

Oral cavity

In 2-3 sentences, explain how infections with Actinomyces typically occur. Correctly use the terms "commensal", "endogenous" and "opportunistic pathogen" in your explanation.

Actinomyces infections are endogenous - they originate from within the same individual. Infections with Actinomyces typically occur when these commensal bacteria, which are normally part of the oral and gastrointestinal flora, become opportunistic pathogens. In order to cause disease, they require disruption of mucosal barriers by trauma (bite), rough feed, foreign bodies, or other similar actions.

E.coli species are:

it depends on the species of E.coli; both are possible

Describe (in 1-2 sentences) the pathogenesis of diarrhea caused by ETEC.

It causes diarrhea by producing heat-labile (LT) and/or heat-stable (ST) enterotoxins that stimulate intestinal epithelial cells to secrete chloride and water into the gut lumen

describe (in 1-2 sentences) the pathogenesis of diarrhea caused by both EPEC and EHEC.

They colonize the gut and proceed to damage  the villi of the gut epithelial cells, resulting into diarrhea and malabsorption through a process called "attachment and effacement".

Which presentation would you expect is LEAST likely to be caused  by an endogenous infection from commensal strain of E.coli?

hemorrhagic diarrhea in a dog

EHEC O157:H7 causes disease in which of the following species? (select all that apply)

humans

E. coli are lactose fermenters; therefore when grown on MacConkey's agar, E.coli colonies will appear:

pink

Explain how Salmonella enterica infection in a laying hen can lead to gastrointestinal disease in a human.

Salmonella enterica can colonize the reproductive tract of a laying hen and contaminate the interior of the egg before the shell forms, or it can contaminate the eggshell after laying. If humans consume raw or undercooked eggs from an infected hen, the bacteria can survive and infect the gastrointestinal tract, leading to salmonellosis.

True or False: Most food-borne salmonella infections from meat are due to contamination with fecal organisms that occurs during meat processing, followed by cooking at an insufficient temperature/time.

TRUE

True or False: Most food-borne salmonella infections from produce are due to contamination with fecal organisms that occurs during application of manure-containing fertilizer, followed by insufficient washing

TRUE

Which is true about enteric Salmonella infections?

severity of disease is highly variable

Salmonella spp grown on MacConkey agar are typically:

White

Antibiotic resistance among Salmonella spp is:

common and of concern

Which of the following are known to cause opportunistic urinary tract infections in dogs?

Klebsiella spp

E.coli spp

Proteus spp

A urinary tract infection with which of the following would predispose a patient to developing struvite uroliths?

Proteus spp

A bacterial culture demonstrating large mucoid colonies on blood agar is most consistent with which species?

Klebsiella spp

A bacterial culture in which the colonies form one large "lawn" over the agar plate is most consistent with which type of bacteria?

Proteus  spp

When grown on MacConkeys agar, Proteus  spp will be:

White

Which of the following are true about Moraxella bovis infections? (Select all that apply)

they can cause rupture of the globe can occur if untreated

flies serve as a mechanical vector for transmission

The most common clinical sign of infection with Brucella spp. is _____________.

Abortion

Based on your reading in the text, give two mechanisms  - one occupational, and one non-occupational - by which humans can be at risk of Brucella infection.

Occupational risk: Veterinarians and farm works are at an increased risk due to their close contact of infected animals during calving, milking,or being in contact with bodily fluids like blood, urine, or the placenta. 

Non-occupation risk: Consumption of unpasteurized dairy products (milk, cheese, or yogurt) from infected animals can lead to the exposure of Brucella infection.

Bordetella spp can cause respiratory disease in multiple species. [A] is a causative agent in "kennel cough" in dogs, and [B] is the causative agent of whooping cough in humans.

A = bronchiseptica

B = B. pertussis

The incubation period for B.bronchiseptica in dogs is:

5-10 days

The best diagnostic procedure for definitively diagnosiing an infection with B.bronchiseptica is:

transtracheal wash

The most appropriate treatment for the average case of kennel cough caused by B.brochiseptica involves:

tincture of time; most cases are self-limiting

Dogs infected with B.brochiseptica have been shown to shed the organism for:

Over a month

Swine with atrophic rhinitis frequently have a coinfection involving two bacteria: [A] and [B]

A = Bordetella

B = Pasteurella multocida

Following a cat bite to the hand. you develop significant swelling and pain at the site. 

Which bacteria, a common oral inhabitant of cats, is most likely to blame?

Pasteurella multocida

A cocker spaniel presents with a long-standing ear infection that has not improved despite several attempts at standard topoical treatment. The discharge is malodorous and has a slight greenish tint; on cytology rods are seen.

A culture and sensitivity are sent out; which of the following bacteria is likely to grow?

Pseudomonas aeruginosa

Many species are frequent aclinical carriers of Pasteurella multocida. One species that is highly likely to be clinically affected is:

Guinea Pigs

Pasteurella multocida infection in rabbits can present as (SELECT ALL THAT APPLY):

Otitis

Abscess formation

Nasal congestion and sneezing

aclinical

Bovine Respiratory Disease Complex typically involves co-infection with multiple bacteria and/or viruses. All of the following are commonly involved bacteria:

Histophilus somni

Mannheimia haemolytica

Pasteurella multocida

What general role do viruses play in Bovine Respiratory Disease Complex?

Viruses play a primary initiating role in Bovine Respiratory Disease Complex by damaging the respiratory epithelium and weakening the immune system, which facilitates secondary bacterial infections.

Why is Pseudomonas so frequently a cause of nosocomial infections?

• Intrinsic resistance to many antibiotics and disinfectants makes Pseudomonas difficult to eliminate in healthcare settings.

• Ability to form biofilms on surfaces like catheters, ventilators, and wounds enhances its survival and persistence in hospitals.