Microbiology - Unit 5 Exam (chapters 11 - 13)

Which of the following statements are true based on the figure below? -A single dose of antibiotics prior to age 1 can increase one's risk of asthma, infections, allergies, and obesity. -Multiple doses of antibiotics throughout life can increase the risk of type 2 diabetes. -Children exposed to a single dose of antibiotics are more likely to have C. difficile infection as older adults. -Antibiotics taken at any time in life can lead to decreased microbiome diversity and an increase in antibiotic-resistant strains in the microbiome. -Antibiotic exposure before birth increases the risk of obesity in children.

-A single dose of antibiotics prior to age 1 can increase one's risk of asthma, infections, allergies, and obesity. -Multiple doses of antibiotics throughout life can increase the risk of type 2 diabetes. -Antibiotics taken at any time in life can lead to decreased microbiome diversity and an increase in antibiotic-resistant strains in the microbiome.

Select those statements that are true about the treatment of biofilm infections. Check all that apply. -Bacteria in biofilms have different susceptibility patterns than their free-living counterparts. -Aminoglycosides generally are very effective against bacteria in biofilms. -Bacteria in biofilms may be inhibited by drugs that interfere with quorum sensing. -Bacteria in biofilms tend to be more antibiotic-sensitive. -Antibiotic-impregnated biomaterials that are inserted into the body prevent biofilm development on those materials.

-Bacteria in biofilms have different susceptibility patterns than their free-living counterparts. -Bacteria in biofilms may be inhibited by drugs that interfere with quorum sensing. -Antibiotic-impregnated biomaterials that are inserted into the body prevent biofilm development on those materials.

Select the major targets of antimicrobial therapy. Cell membrane structure and/or function Cell wall synthesis Flagellar assembly DNA/RNA structure and/or function Protein synthesis ATP synthesis Folic acid synthesis

-Cell membrane structure and/or function -Cell wall synthesis -DNA/RNA structure and/or function -Protein synthesis -Folic acid synthesis

Select the antiprotozoal drugs from this list. Check all that apply. -Chloroquine -Primaquine -Ivermectin -Albendazole -Fluconazole -Artemisinin -Metranidazole

-Chloroquine -Primaquine -Artemisinin -Metranidazole

Select the five major mechanisms of antimicrobial resistance. -Enzymatic inactivation of the antibiotic -Microbe utilizes the antibiotic as an energy source -Antibiotic efflux pumps pump the antibiotic out of the cell -Altered target site, such that the antibiotic can no longer bind to the target -Microbe uses an alternative pathway to circumvent a blocked pathwayses an alternative pathway to circumvent a blocked pathway -Decreased permeability to the antibiotic

-Enzymatic inactivation of the antibiotic -Antibiotic efflux pumps pump the antibiotic out of the cell -Altered target site, such that the antibiotic can no longer bind to the target -Microbe uses an alternative pathway to circumvent a blocked pathwayses an alternative pathway to circumvent a blocked pathway -Decreased permeability to the antibiotic

Select the methods of antimicrobial susceptibility testing that can be used to determine minimal inhibitory concentrations (MIC). -Kirby-Bauer test -Etest -Tube dilution test -Beta-lactamase testing

-Etest -Tube dilution test

Select the four main categories of antifungal agents. -Aminoglycosides -Macrolide polyenes -Beta-lactams -Azoles -Echinocandins -Allylamines

-Macrolide polyenes -Azoles -Echinocandins -Allylamines

Review the table and graph below, and select all of the statements that are reflected by the data. -Mice that were given any of the tested antibiotics had higher body fat percentages than those mice receiving no antibiotics. -There was a significant difference in both weight and the body fat % between the control and treatment groups. -Animals receiving penicillin had the highest body fat percentages. -Antibiotics should be avoided to reduce obesity in humans.

-Mice that were given any of the tested antibiotics had higher body fat percentages than those mice receiving no antibiotics. -Animals receiving penicillin had the highest body fat percentages.

Select the three primary mechanisms by which antiviral medications work. -Preventing viral cell wall synthesis -Preventing entry of the virus into the host cell -Directly disrupting viral capsids -Blocking transcription and translation of viral proteins -Preventing the maturation of viral particles -Directly disrupting viral envelopes

-Preventing entry of the virus into the host cell -Blocking transcription and translation of viral proteins -Preventing the maturation of viral particles

Select the two ways in which microorganisms acquire antimicrobial resistance. -Spontaneous mutation -Antibiotic-induced mutations -Transfer of genes from their human or animal host -Transfer of genes from other microorganisms -Through nutritional starvation

-Spontaneous mutation -Transfer of genes from other microorganisms

Select two genera of bacteria and two genera of fungi that have produced the greatest number of antibiotic drugs. -Streptomyces -Bacillus -Clostridium -Toxoplasma -Penicillium -Cephalosporium

-Streptomyces -Bacillus -Penicillium -Cephalosporium

Select the correct statements about linezolid and synercid. -Synercid and linezolid are two of the newer antibiotics that inhibit protein synthesis. -Synercid and linezolid are used to treat some of the very resistant gram-positive bacteria. -Synercid and linezolid are relatively toxic to the kidneys. -Synercid inhibits initiation of protein synthesis while linezolid inhibits the action of the 50S ribosome and translation. -Synercid and linezolid are effective antitubercular antibiotics.

-Synercid and linezolid are two of the newer antibiotics that inhibit protein synthesis. -Synercid and linezolid are used to treat some of the very resistant gram-positive bacteria.

Select the statements that accurately reflect characteristics of carbapenem drugs. -They are beta-lactam drugs. -They target ribosomal action. -Doripenem and imipenem are newer examples of carbapenem drugs. -They are commonly used in many healthcare facilities as first-line drugs. -The NDM enzyme can confer resistance to carbapenem drugs.

-They are beta-lactam drugs. -Doripenem and imipenem are newer examples of carbapenem drugs. -The NDM enzyme can confer resistance to carbapenem drugs.

Select the two correct answers to test your understanding of the primary goals of antimicrobial treatment. -To destroy the infective agent -To kill malignant cells -To be nontoxic to the host and produce no side effects -To identify the cause of infection -To alter the normal microbiota of the patient

-To destroy the infective agent -To be nontoxic to the host and produce no side effects

Select potential new antimicrobial therapies that are under investigation. Check all that apply. -Use of probiotics to contribute healthy microbes to the GI tract -Methods that directly interfere with cell respiration in bacteria -Bacteriophage therapy -Use of prebiotics to feed normal inhabitants of the GI tract -Introduction of healthy biota through fecal transplantation -Interfering with synthesis of bacterial capsules/glycocalyx

-Use of probiotics to contribute healthy microbes to the GI tract -Bacteriophage therapy -Use of prebiotics to feed normal inhabitants of the GI tract -Introduction of healthy biota through fecal transplantation

Select the antibiotics, other than beta-lactam drugs, that also inhibit bacterial cell wall synthesis. -Vancomycin -Gentamicin -Isoniazid -Tetracycline -Bacitracin -Ceftriaxone

-Vancomycin -Isoniazid -Bacitracin

Review various thermal death measurements by completing each sentence.

Adequate sterilization requires that both temperature and length of exposure be properly controlled. In general, higher temperatures allow shorter exposure times, while lower temperatures require longer exposure times. In terms of these strategies, the thermal death time is defined as the shortest length of time required to kill all test microbes at a specified temperature. An optional measurement used to compare the susceptibility of microbes to heat is the thermal death point, which is defined as the lowest temperature required to kill all microbes in a sample in 10 minutes.

Microbial resistance to drugs is acquired through ______.

All of these are means by which resistance can be transferred between bacteria.

Disinfection procedures must take into account _________.

All of these choices must be taken into account.

Review the cellular targets of physical and chemical antimicrobial agents by completing each sentence.

An antimicrobial agent's adverse effect on cells is known as its mode of action. Such antimicrobials exhibit a range of cellular targets, the least selective being the most effective against the widest range of microbes and the most selective agents exhibiting specificity in terms of cellular targets and microbial types they are effective against. Potential cellular targets of various physical and chemical forms of antimicrobials include the cell wall, whose synthesis can be blocked by these agents or whose structure can be altered as well. Another potential target is the cell membrane, whose surface tension can be reduced by various microbicidal agents resulting in a loss of selective permeability in the cell. Physical and chemical agents can also interfere with protein synthesis through disruption of ribosome activity, protein function through the denaturation of a protein's native state, and finally disrupting the synthesis or structure of nucleic acids.

Choose the phrase that best describes a superinfection.

An infection that occurs due to the overgrowth of other potentially pathogenic microbes during or after initial antimicrobial therapy

Because of its ability to decompose into oxygen and water, hydrogen peroxide is very useful against what group of organisms?

Anaerobic bacteria

The antibiotics listed here all have similar minimum inhibitory concentrations. Choose the antibiotic that would be the best option for treatment.

Antibiotic Y Therapeutic Index = 100

Pick the true statement about antibiotics.

Antibiotics are natural products of microorganisms.

Choose the statement that correctly explains how an antibiotic that inhibits protein synthesis can be selective.

Antibiotics bind to the 70S bacterial ribosomes but not to the 80S eukaryotic ribosomes.

Review the characteristics of chemical agents of microbial control by completing each sentence.

Antimicrobial chemicals occur in liquid, gaseous, or even solid forms. They range from disinfectants and antiseptics to sterilants and preservatives, which are chemicals which can be used to inhibit the deterioration of food products. The use of chemical agents as germicides is very important in health-related fields today, due to their ability to have rapid action in low concentrations and their ability to remain functional when solubolized in water or alcohol. In addition, many of these agents have broad-spectrum microbicidal action without exhibiting toxicity as well as the ability to sustain a persistent action on inanimate surfaces. Other agents are resistant to the inactivating action of organic matter, while others exhibit noncorrosive, sanitizing, or deodorizing properties. Many are affordable and readily available to users.

Select the statement that most accurately reflects characteristics of surfactants.

Cationic detergents exhibit more potent antimicrobial activity than anionic detergents.

Which of the following represents one of the four major targets of antimicrobial agents?

Cell wall

Which of the following represents a correct pairing of an antimicrobial drug and its cellular target?

Cephalosporins--cell wall

Select the statement that best describes the antimicrobial activity of chlorhexidine.

Chlorhexidine targets cell membrane components and denatures proteins.

Match the chemical agent with its common application.

Chlorine Gas: Large scale disinfection of drinking water Hypochlorites: Disinfection in restaurants, hospitals, homes, and pools/spas Skin and tissue antisepsis Iodophors: Skin and tissue antisepsis

Select the phrase that describes the antimicrobial activity of alcohols.

Disrupt membrane lipids and denature proteins

The production of beta-lactamases is an example of which mechanism of drug resistance?

Drug inactivation

Select the microorganism that is least resistant to chemical and physical control measures

Enveloped viruses

Desiccation is a form of physical control of microorganisms that can be used in moist or dry forms.

False

Mercury is a heavy metal that today is increasingly incorporated into plastic, steel, and textiles to create antimicrobial surfaces and clothing.

False

Moist heat methods operate at higher temperatures and longer exposure times as compared to dry heat methods.

False

Nonionizing radiation exhibits good penetrating power and can be used for cold sterilization.

False

Regarding use of heat to control microbial growth, dry heat at lower temperatures is as effective as moist heat at the same temperature.

False

Choose the microbial control method that neither inhibits nor kills microbes, but instead physically removes them from liquids or air.

Filtration

Choose the aldehyde that is the most toxic, limiting its clinical usefulness.

Formaldehyde/formalin

Select which non-beta-lactam phosphoric acid agent is used today as an alternative treatment for urinary tract infections caused by enteric bacteria.

Fosfomycin

Choose the method used to sterilize an inoculation loop used in lab for culturing bacteria.

Incineration

Select the dry heat method of microbial control from the following examples.

Incineration

Choose the method of antimicrobial susceptibility testing that involves measuring and evaluating zones of inhibition around antibiotic disks placed on a culture of bacteria prior to incubation.

Kirby-Bauer test

Select the statement that most accurately reflects characteristics of fluoroquinolone drugs.

Levofloxacin is a third-generation fluoroquinolone used in cases of resistant bacterial infections.

Review novel antimicrobial strategies that are under investigation in laboratories today by completing the sentences.

Many novel approaches are being investigated as an alternative to antimicrobial drugs. For example, researchers are testing the effectiveness and safety of using bacteriophages to specifically target one bacterial species. Because of our understanding of the importance of the normal microbiota, other strategies for controlling infection aim at replacing or supplementing those organisms. The use of probiotics, preparations of live microorganisms that are ingested to improve intestinal biota, and prebiotics, nutrients that encourage the growth of beneficial intestinal microbes, are being pursued as an alternative to the use of traditional antibiotics that are more problematic. Another technique, fecal transplants, has been used to treat recurrent infections with Clostridioides difficile by replacing organisms of the gut microbiome.

Match the antibiotic to its description to test your understanding of the different antibacterials in the penicillins group.

Penicillin G and Penicillin V - Generally most effective against gram-positive bacteria. Methicillin - Effective against penicillinase-producing bacteria. Ampicillin - Broad spectrum drug, used against gram-negative enteric bacteria. Clavulanic Acid - Added to penicillins to inhibit beta-lactamases.

Choose the antimicrobial category that is most selectively toxic.

Penicillins that inhibit cell wall synthesis

Match the term to its description to test your understanding of the use of moist heat methods to control microbial growth.

Steam under pressure: This method requires the use of an autoclave. To sterilize, temperature must reach 121°C for a minimum of 15 minutes. Pasteurization: Heat is applied to beverages to prevent spoilage and kill pathogens, but it does not sterilize. Protocols include holding liquids at 71.6°C for 15 seconds or at 63°C for 30 minutes. Boiling water: This exposes a material to a temperature of 100°C. Thirty minutes of exposure will disinfect but will not sterilize.

Match the term with its description to test your understanding of microbial control terminology.

Sterilization - Destruction of all microbial life Disinfection - Destruction of most microbial life on inanimate surfaces Antisepsis - Destruction of most microbial life on living tissue Decontamination - Mechanical removal of most microbes from living or inanimate surfaces

Complete the sentences to test your knowledge of factors affecting microbial death rate.

The effectiveness of a particular microbicidal agent is governed by several factors besides time. The number of microbes affects the action of an agent, as does the composition of the population. The temperature as well as the pH level of the environment will also influence the action of microbicidal agents. The concentration of the agent as well as its mode of action against microbes also play a role in its ability inactivate microbes. Finally, the presence of organic matter, such as saliva and blood, also inhibits the action of many microbicidal agents.

Complete the sentences to review the characteristics of ideal antimicrobial drugs.

The goal of antimicrobial therapy is to deliver a drug that will destroy the pathogen without harming the host. An ideal antimicrobial drug is microbicidal rather than microbiostatic, and is relatively soluble. An ideal drug remains potent long enough to act, but does not lead to the development of antimicrobial resistance in microbial populations. An effective drug assists the host's defenses and should not cause allergies or other infections. An ideal drug should be readily delivered to the site of infection in the host, and overall, the drug should be reasonably priced.

Choose the statement that identifies the major disadvantage of both cold and desiccation in terms of microbial control.

These methods are bacteriostatic rather than bactericidal.

Match the heavy metal product with its microbial use.

Topical germicide on mouth ulcers and root canals - Silver nitrate Used in an ointment on 2nd and 3rd degree burns - Silver sulfadiazine Incorporated into urinary catheters - Pure silver ions

Select the most disadvantageous characteristic(s) of phenolics.

Toxicity and resistance

DNA repair mechanisms can help alleviate the effects of _______.

UV radiation

Transcription is targeted most directly by ______.

UV radiation

What represents a nonionizing form of radiation, often used for disinfection purposes?

UV radiation

A compound synthesized by bacteria or fungi that destroys or inhibits the growth of other microbes is a(n) ______.

antibiotic

An antimicrobial drug that is effective against a very diverse array of bacteria is described as _______ spectrum, whereas a drug that is very selective for a just a few different types of bacteria is described as _______ spectrum.

broad; narrow

A(n) ______ agent would be used to destroy bacteria on a countertop whereas a(n) _______ agent would be used on skin prior to making an incision.

disinfectant; antiseptic

Microbial control methods that kill ______ are able to sterilize.

endospores

Gentamicin, streptomycin, tetracycline, clindamycin, and erythromycin are _______.

examples of antibiotics that inhibit protein synthesis

A narrow spectrum antimicrobial would be an appropriate choice to treat an abscess caused by several different microbe species, including both gram-negative and gram-positive bacteria.

false

An effective antimicrobial drug will only destroy 30% of the host's cells.

false

Drugs that block quorum-sensing pathways among bacterial cells have unfortunately been ineffective thus far in treating biofilm infections.

false

Many antibiotic drugs exhibit a high level of selective toxicity because the structure targeted by the drug is common to both the infectious agent and the host.

false

Solutions of antimicrobial chemicals dissolved in pure water are termed tinctures, while those dissolved in pure alcohol are termed aqueous.

false

Superinfections are most likely to result from treatment with narrow spectrum antimicrobials.

false

The shortest length of time required to kill all test microbes at a specified temperature is the thermal death point.

false

The most versatile method for sterilizing heat-sensitive liquids is _______.

filtration

Cytoplasmic enzymes are most likely to be disrupted by ______.

high temperatures

Drugs that prevent the formation of the bacterial cell wall are _______.

penicillins

The lowest temperature required to kill all microbes in a sample within 10 minutes is the thermal death _______.

point

What strategy involves the use of nutrients to directly encourage the growth of existing healthy biota?

prebiotics

The two microbial forms most resistant to chemical and physical control measures are _______ or proteinaceous infectious particles, and ______ produced by Bacillus and Clostridium species.

prions; endospores

The feature of an antimicrobial that allows it to kill or inhibit microbes yet be harmless to the host is referred to as _______.

selective toxicity

Cationic detergents are surface active agents, also known as ______, which damage bacteria by binding bacterial surface proteins and disrupting ______.

surfactants; cell membranes

Sanitization is a process by which _______.

the microbial load on an object is reduced

The ratio of the toxic dose of an antimicrobial drug (that is toxic to humans) to its minimum therapeutic dose is the _______.

therapeutic index

Direct damage to tissue or an organ due to the effect of an antimicrobial on that tissue or organ is known as drug ______, whereas an inappropriate immune reaction to an antimicrobial is known as drug-induced _______.

toxicity; allergy

A chemical labeled as bactericidal will kill bacteria whereas a chemical labeled as bacteriostatic will inhibit bacterial growth but will not kill them.

true

Azidothymidine, or AZT, is a drug used in the treatment of HIV infection that exhibits a high degree of selective toxicity.

true

Environmental microbes are now recognized as important reservoirs of antimicrobial resistance genes.

true

Penicillins account for the greatest number of antimicrobial allergies today.

true

Salting of meat prior to the development of refrigeration technology was an example of using osmotic pressure to control microbial spoilage of this food product.

true

The newly created field of "click chemistry" has provided another vital source of semisynthetic drugs today.

true