Question 1

A hospital is experiencing an outbreak of a Gram-negative bacterial infection. The bacteria are found to be resistant to penicillins due to the production of beta-lactamase. Which of the following strategies would most effectively restore the efficacy of penicillin therapy in this scenario?

Accepted Answer

Administering a combination of penicillin and a beta-lactamase inhibitor such as clavulanic acid

Question 2

During the exponential (log) phase of bacterial growth, which of the following statements is TRUE regarding the population?

Accepted Answer

The population is most sensitive to antibiotics that target cell wall synthesis

Question 3

A microbiologist wants to determine the number of living bacteria in a water sample. Which method should they use, and why?

Accepted Answer

Viable plate count, because it only counts living, dividing cells

Question 4

A culture starts with 10 bacterial cells. If the generation time is 40 minutes, how many cells will there be after 4 hours? Use the formula $$N_f = N_i 	imes 2^n.$$

Accepted Answer

$$N_f = 10 	imes 2^6$ = 640$$

Question 5

Which of the following best explains why moist heat is more effective than dry heat for sterilization at lower temperatures and shorter times?

Accepted Answer

Water aids in the denaturation of proteins, allowing for more efficient microbial killing

Question 6

A patient is diagnosed with a Mycobacterium tuberculosis infection. Which drug would be most appropriate due to its specific mechanism of action?

Accepted Answer

Isoniazid, because it inhibits mycolic acid synthesis in the cell wall

Question 7

Which of the following statements about the Kirby-Bauer disc diffusion test is CORRECT?

Accepted Answer

It measures the zone of inhibition to assess bacterial susceptibility to antibiotics

Question 8

A new antifungal drug is found to inhibit $$\beta-1$$,3-D-glucan synthase. Which group of drugs does it most closely resemble in its mechanism of action?

Accepted Answer

Echinocandins

Question 9

Which of the following is the correct order of microbial resistance from most resistant to least resistant to chemical control methods?

Accepted Answer

Prions \u003e Bacterial endospores \u003e Mycobacterium \u003e Protozoan cysts \u003e Vegetative bacterial cells

Question 10

A patient is prescribed a combination of two antibiotics that work better together than alone, allowing for lower doses and increased effectiveness. This clinical strategy is known as:

Accepted Answer

Drug synergy

Question 11

Which of the following best describes the mechanism of action of sulfonamide drugs?

Accepted Answer

They act as metabolic analogs of PABA, blocking folic acid synthesis

Question 12

A laboratory technician is tasked with sterilizing a heat-sensitive liquid, such as a vaccine. Which method should be used?

Accepted Answer

Filtration through a membrane with small pores

Question 13

Which of the following is a TRUE statement about the use of alcohols as chemical control agents?

Accepted Answer

They are most effective at 70% concentration because water is required for protein coagulation

Question 14

A patient with a severe Candida infection is treated with an antifungal that binds to ergosterol in the fungal membrane, causing loss of selective permeability. Which drug is this?

Accepted Answer

Amphotericin B

Question 15

Which of the following mechanisms is NOT a common way that bacteria develop resistance to antibiotics?

Accepted Answer

Increasing the rate of binary fission to outpace the drug

Question 16

A patient is infected with a parasite that is treated with praziquantel. What is the primary mechanism by which this drug acts?

Accepted Answer

It increases calcium ion permeability, causing muscle contraction and paralysis

Question 17

Which of the following best describes the action of nonionizing (UV) radiation as a physical control method?

Accepted Answer

It creates abnormal thymine dimers in DNA, inhibiting replication

Question 18

A patient is prescribed a drug that inhibits DNA gyrase, preventing DNA from unwinding during replication. Which class of drugs does this describe?

Accepted Answer

Fluoroquinolones

Question 19

Which of the following statements about the therapeutic index (TI) is CORRECT?

Accepted Answer

A higher TI indicates a greater margin of safety for the patient

Question 20

A microbiologist is working with a bacterium that can survive in high salt concentrations up to 25% NaCl. This organism is best classified as a:

Accepted Answer

Halophile

Microbial Growth, Control, and Antimicrobial Drugs: Structured Study Notes

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