Exam 5 - Review Microbiology 2421 (Chp. 15 & 20)

Important characteristics of antimicrobial drugs include

• Lock toxicity for human tissue

• High toxicity against microbial cells

• A lack of serious side effects in humans

• Stability in body tissues and fluids

• All of the choices are correct

All of the choices are correct

Aminoglycosides

Attach to the 30S ribosomal subunit and disrupt protein synthesis

Ampicillin, amoxicillin, mezlocillin, and penicillin G all have

A beta-lactam ring

What drug is used in cases of penicillin and methicillin resistance and also used to treat endocarditis?

Vancomycin

Antimicrobials effective against a wide variety of microbial types are termed ______.

Broad spectrum drugs

Penicillins and cephalosporins

Block the peptidases that cross-link glycan molecules

What drug is used to treat cases of tuberculosis

Isoniazid

Which antibiotic is used to treat MRSA and VRE infections?

Linezolid

The drug that is used to treat typhoid fever and brain abscesses, but can cause aplastic anemia, is

Chloramphenicol

Drugs that insert on the _____ ribosomal subunit prevent peptide bond formation or inhibit translocation of the subunit during translation.

50S

Each of the following target bacterial ribosomes, except

Polynyxins

Selective toxicity refers to damage to

The target organisms but not vertebrate cells

Substances that are naturally produced by certain microorganisms that can inhibit or destroy bacteria are called

Antibiotics

The antifungal drug that can be used to treat serious systemic fungal infections is _____

Amphotericin B

Sulfonamides

Are metabolic analogs of PABA and block folic acid synthesis

A chemical that inhibits beta-lactamase enzymes is ______.

Clavulanic acid

Ketoconazole, fluconazole, clotrimazole, and miconazole are broad-spectrum azoles used to treat _____ infections.

Fungal

Each of the following affect cell walls, except ______.

Erythromycin

Antibiotics that disrupt bacterial ribosomes can also affect

Eukaryotic mitochondrial ribosomes

The use of a drug to prevent imminent infection is called

Prophylaxis

Which organism in Table 15.2 most easily causes an infection?

Legionella pneumophila

Injectable drugs are tested for endotoxins by

The Limulus amoebocyte lysate test

Table 15.1 shows the ID50 for Staphylococcus aureus in wounds with and without the administration of ampicillin before surgery. Based on the data, the administration of ampicillin before surgery

Decrease the risk of staphylococcal infection

Siderophores are bacterial proteins that compete with the host's

Iron-transport proteins

Endotoxins are

Part of the gram-negative cell wall

The ability of some microbes, such as Trypanosoma or Giardia to alter their surface molecules and evade destruction by the host's antibodies is called

Antigenic variation

The ID_50 is

The dose that will cause an infection in 50 percent of the test population

Which of the following contributes to the virulence of a pathogen?

Numbers of microorganisms that gain access to a host, evasion of host defenses, and toxin production

Which of the following statements about exotoxins is generally FALSE?

They are resistant to heat

Which of the following is NOT a membrane-disrupting toxin?

A-B toxin

Symptoms of protozoan and helminthic diseases are due to

Tissue damage due to growth of the parasite on the tissues, waste products excreted by the parasite, and products released from damaged tissue

The most frequently used portal of entry for pathogens is the

Mucous membranes of the respiratory tract

Gram-negative septic shock results from the following events. What is the second step? .

LPS is released from gram-negative bacteria .

All of the following organisms produce exotoxins EXCEPT

Salmonella typhi

Superantigens produce intense immune responses by stimulating lymphocytes to produce

Cytokines

Which organism in Table 15.2 causes the most severe disease?

It cannot be determined from the information provided

All of the following contribute to a pathogen's invasiveness EXCEPT

Toxins

Cytopathic effects are changes in host cells due to

Viral infections

Which of the following statements is FALSE?

Coagulase destroys blood clots

The fimbriae of Neisseria gonorrhea and enteropathogenic E. coli are examples of

Adhesins and ligands

Most pathogens that gain access through the skin

Enter through hair follicles and sweat ducts

Which of the following does NOT contribute to the symptoms of a fungal disease?

Cell walls

All of the following are methods of avoiding host antibodies EXCEPT

Membrane-disrupting toxins

All of the following are examples of entry via the parenteral route EXCEPT

Hair follicle

Botulism is caused by ingestion of a proteinaceous exotoxin; therefore, it can easily be prevented by

Boiling food prior to consumption

Which of the following cytopathic effects is cytocidal?

Release of enzymes from lysosomes

All of the following are used by bacteria to attach to host cells EXCEPT .

A-B toxins .

Which of the following statements about staphylococcal enterotoxin is FALSE?

It is produced by Staphylococcus aureus growing in the host’s intestines

Lysogenic bacteriophages contribute to bacterial virulence because bacteriophages

Give new gene sequences to the host bacteria

Twenty-five people developed symptoms of nausea, vomiting, and diarrhea three to six hours after attending a church picnic where they ate a ham and green bean casserole with cream sauce. The most likely cause of this case of food intoxication is

Erythrogenic toxin

Which of the following statements about M protein is FALSE?

It is readily digested by phagocytes

Symptoms of intense inflammation and shock occur in some gram-positive bacterial infections due to

Superantigens

Which of the following is an example of direct damage due to bacterial infection?

The invasion and lysis of intestinal cells by coli

Polio is transmitted by ingestion of water contaminated with feces containing polio virus. What portal of entry does polio virus use?

Mucous membrane only

All of the following bacteria release endotoxin EXCEPT

Clostridium botulinum

Cholera toxin polypeptide A binds to surface gangliosides on target cells. If the gangliosides were removed,

Polypeptide B would not be able to enter the cells.

Bacteria such as E. coli and Salmonella produce invasins that bind host cells, thus causing the cells to

Engulf the bacteria

Which of the following mechanisms is used by gram-negative bacteria to cross the blood-brain barrier?

Inducing TNF

Endotoxins in sterile injectable drugs could cause

Septic shock symptoms

Which of the following is NOT a cytopathic effect of viruses

Toxin production

Bacteria that cause periodontal disease have adhesins for receptors on streptococci that colonize on teeth. This indicates that

Streptococcal colonization is necessary for periodontal disease

Nonpathogenic Vibrio cholerae can acquire the cholera toxin gene by

Transduction

In response to the presence of endotoxin, phagocytes secrete tumor necrosis factor. This causes

A decrease in blood pressure

Patients developed inflammation a few hours following eye surgery. Instruments and solutions were sterile, and the Limulus assay was positive. The patients' inflammation was due to

Endotoxin

Penicillin was considered a "miracle drug" for all of the following reasons EXCEPT

It was the first antibiotic

A drug that inhibits mitosis, such as griseofulvin, would be more effective against

Fungi

Most of the available antimicrobial agents are effective against

Bacteria

Antimicrobial peptides (AMPs) frequently work by

Disrupting the plasma membrane

In what way are semisynthetic penicillins and natural penicillins alike?

Both are based on β-lactam.

Which of the following antibiotics is NOT bactericidal?

Polyenes

Which one of the following does NOT belong with the others?

• Bactiracin

• Cephalosporin

• Monobactam

• Penicillin

• Streptomycin

Streptomycin

The antibiotic tetracycline binds to the 30S subunit of the ribosome, as shown by the dark black bar on the right portion of the diagram in Figure 20.1. The effect is to

Interfere with the attachment of the tRNA to mRNA-ribosome complex

The antibiotic chloramphenicol binds to the 50S subunit of the ribosome, as shown in Figure 20.2. The effect is to

Prevent peptide bond formation in prokaryotes

Which of the following antimicrobial agents has the fewest side effects?

Penicillin

Which of the following drugs does NOT act by competitive inhibition?

Streptomycin

Which of the following methods of action would be bacteriostatic?

Inhibition of protein synthesis

Which of the following antibiotics is recommended for use against gram-negative bacteria?

Polymyxin

Which of the following antimicrobial agents is recommended for use against fungal infections?

Amphotericin B

In Table 20.1, as illustrated by the data shown, the minimal bactericidal concentration of antibiotic X is

15 μg/ml

In Table 20.1, the minimal inhibitory concentration of antibiotic X is

10 μg/ml

More than half of our antibiotics are

Produced by bacteria

To date, most of our natural antibiotics have been found to be produced by members of what genus

Streptomyces

Which of the following is mismatched?

• Ehrlich — "magic bullet" theory

• Fleming — initial identification of penicillin's effect on gram-positive microbial growth

• Florey and Chain — identification of Penicillium as the producer of penicillin

• Kirby and Bauer — disc-diffusion method

Florey and Chain — identification of Penicillium as the producer of penicillin

Which compound would be the most useful to treat candidiasis?

Flucytosine

Which of the following antibiotics are used to treat fungal infections?

• aminoglycosides

• cephalosporins

• griseofulvin

• polyenes

• bacitracin

3 and 4

Which of the following antibiotics does NOT interfere with cell wall synthesis?

Macrolides

The antimicrobial drugs with the broadest spectrum of activity are

Tetracyclines

Which of the following statements is FALSE?

Interferon inhibits glycolysis

Protozoan and helminthic diseases are difficult to treat because

Their cells are structurally and functionally similar to human cells

Which of the following organisms would MOST likely be sensitive to natural penicillin?

Streptococcus pyogenes

Which of the following statements about drug resistance is FALSE?

It is found only in gram-negative bacteria

Which of the following does NOT constitute an advantage of using two antibiotics together?

Two are always twice as effective as one

Drug resistance occurs

When antibiotics are used indiscriminately

In Table 20.2, the most effective antibiotic tested was

D

In Table 20.2, the antibiotic that exhibited bactericidal action was

The answer cannot be determined based on the information provided

In Table 20.2, which antibiotic would be most useful for treating a Salmonella infection?

The answer cannot be determined based on the information provided

Which of the following would be selective against the tubercle bacillus?

Ethambutol — inhibits mycolic acid synthesis

In the presence of penicillin, a cell dies because

It undergoes lysis

Lamisil is an allylamine used to treat dermatomycoses. Lamisil's method of action is similar to that of

Azole antibiotics

Niclosamide prevents ATP generation in mitochondria. You would expect this drug to be effective against

Helminths