MICRO 6/7 Microbial Growth and Control

Iodophors differ from iodine (I2) in that iodophors Don't stain. Are less irritating. Are longer lasting. Are combined with a nonionic detergent. All of these.

All of these

In Figure 6.1, which line best depicts a catalase-negative cell incubated aerobically? a b c

?

In Figure 6.1, which line best depicts Neisseria gonorrhoeae when growing inside the human body? a b c

A

In Figure 6.1, which line best illustrates the growth of a facultative anaerobe incubated aerobically? a b c

A

In Table 6.1, which medium (media) is (are) chemically defined? A B C A and B A and C

A

In Table, 6.1, in which medium would an autotroph grow? A B C A and B A and C

A

In one hospital, Pseudomonas aeruginosa serotype 10 infected the biliary tract of 10% of 1300 patients who underwent gastrointestinal endoscopic procedures. After each use, endoscopes were washed with an automatic reprocessor that flushed detergent and glutaraldehyde through the endoscopes, followed by a tap water rinse. P. aeruginosa 10 was not isolated from the detergent, glutaraldehyde, or tap water. What was the source of the infections? Bacterial cell walls in the water A biofilm in the reprocessor Contaminated disinfectant Fecal contamination of the bile ducts (Couldn't get image)

A biofilm in the reprocessor

Which of the following is a limitation of the autoclave? Requires a long time to achieve sterilization Cannot inactivate viruses Cannot kill endospores Cannot be used with heat-labile materials Cannot be used with glassware

Cannot be used with heat-liable materials

Which of the following does NOT directly result from application of heat? Breaking of hydrogen bonds Breaking of sulfhydryl bonds Denaturing of enzymes Cell lysis Damage to nucleic acids

Cell lysis

Which of the following substances is used for surgical hand scrubs? Phenol Chlorine bleach Chlorhexidine Soap Glutaraldehyde

Chlorhexidine

Which of the following is an advantage of the direct microscopic count? Can readily count organisms that are motile Enumerates dead cells Requires no incubation time Sample volume is unknown. Requires a large number of cells

Requires no incubation time

Which of the following best describes the pattern of microbial death? The cells in a population die at a constant rate. All the cells in a culture die at once. Not all of the cells in a culture are killed. The pattern varies depending on the antimicrobial agent. The pattern varies depending on the species.

The cells in a population die at a constant rate.

Which of the following is the best definition of generation time? The length of time needed for lag phase The length of time needed for a cell to divide The minimum rate of doubling The duration of log phase The time needed for nuclear division

The length of time needed for a cell to divide

Which of the following pairs is mismatched? Psychrotroph - growth at 0°C Thermophile - growth at 37°C Mesophile - growth at 25°C Psychrophile - growth at 15°C Hyperthermophiles - growth at 100°C

Thermophile - growth at 37 degrees C

Which of the following treatments is the most effective for controlling microbial growth? 63°C for 30 min. 72°C for 15 sec. 140°C for 4 sec. They are equivalent treatments. None is effective.

They are equivalent treatments

Which of the following will NOT inactivate endospores? Autoclave Chlorine dioxide High pressure Plasma Supercritical CO2

High pressure

Most bacteria grow best at pH 1. 5. 7. 9. 14.

7

Place the following surfactants in order from the most effective to the least effective antimicrobial activity:1-Soap; 2-Acid-anionic detergent; 3-Quats. 1, 2, 3 1, 3, 2 2, 1, 3 3, 2, 1 3, 1, 2

3, 2, 1

In Figure 7.2, the decimal reduction time (D value) for the culture is approximately 0 min. 15 min. 30 min. 45 min. 60 min.

15 min

Three cells with generation times of 30 minutes are inoculated into a culture medium. How many cells are there after 5 hours? 3 x 210 1024 243 48 16

3 x 2^10

Thirty-six colonies grew in nutrient agar from 1.0 ml of undiluted sample in a standard plate count. How many cells were in the original sample? 4 9 18 36 72

36

An experiment began with 4 cells and ended with 128 cells. How many generations did the cells go through? 64 32 6 5 4

5

In Figure 7.1, what is the thermal death time for culture (a)? 150°C 60 min. 120 min. 100°C Can't tell

60 min

In Figure 7.2, the thermal death time for this culture is 0 min. 10 min. 20 min. 40 min. 60 min.

60 min

Which one of the following does NOT belong with the others? Acid-anionic detergents Benzoic acid Supercritical CO2 Pasteurization Peracetic acid

Acid-anionic detergents

In Figure 6.1, which line best depicts a facultative anaerobe in the absence of O2? a b c

B

In Figure 6.1, which line best depicts a psychrotroph incubated at 0°C? a b c

B

Micrococci are facultative halophiles. In Figure 6.1, which line best depicts the growth of Micrococcus luteus in a nutrient medium containing 7.5% NaCl? a b c

B

Which graph in Figure 7.3 best depicts the effect of placing the culture in an autoclave for 15 min. at time x? a b c d e

B

In Figure 6.2, which sections of the graph illustrate a logarithmic change in cell numbers? a and c b and d a and b c and d b only

B & D

Which of the following substances is NOT used to preserve foods? Biguanides Nisin Potassium sorbate Sodium nitrite Sodium propionate

Biguanides

Patients with indwelling catheters are susceptible to infections because Injected solutions are contaminated. Their immune systems are weakened. Infections can be transmitted from other people. Biofilms develop on catheters. Bacteria cause infections

Biofilms develop on catheters

The addition of which of the following to a culture medium will neutralize acids? Buffers Sugars pH Heat Carbon

Buffers

In Table 7.1, which compound was the most effective against E. coli? A B C D Can't tell

Can't tell

In Table 7.3, which disinfectant was most effective against Salmonella? oom K.O. Mortum Sterl Can't tell

Can't tell

Which graph in Figure 7.3 best depicts the effect of placing the culture at 7°C at time x? a b c d e

D

Which of the following is an advantage of the standard plate count? Can readily count cells that form aggregates Requires incubation time Determines the number of viable cells Chemical and physical requirements are determined by media and incubation. Cannot be used to count bacteria in food

Determines the number of viable cells

The data in Table 6.2 indicate that S. aureus is a(n) Mesophile. Facultative anaerobe. Facultative halophile. Aerobe. Halophile.

Facultative halophile

Which of the following is an example of a metabolic activity that could be used to measure microbial growth? Standard plate count Glucose consumption Direct microscopic count Turbidity MPN

Glucose consumption

Which one of the following does NOT belong with the others? Beta-propiolactone Glutaraldehyde Ethylene oxide Hydrogen peroxide Propylene oxide

Hydrogen peroxide

Salts and sugars work to preserve foods by creating a Depletion of nutrients. Hypotonic environment. Lower osmotic pressure. Hypertonic environment. Lower pH.

Hypertonic environment

In Table 7.3, which disinfectant was bactericidal? Doom K.O. Mortum Sterl Can't tell

Mortum

Which of the following does NOT achieve sterilization? Dry heat Pasteurization Autoclave Formaldehyde Ethylene oxide

Pasteurization

Bone and tendons for transplant are decontaminated by Ethylene oxide. Glutaraldehyde. Peroxygens. Plasma sterilization. Supercritical fluids.

Supercritical fluids

The antimicrobial activity of chlorine is due to which of the following? The formation of hypochlorous acid The formation of hydrochloric acid The formation of ozone The formation of free O Disruption of the plasma membrane

The formation of hypochlorous acid

Which of the following is NOT used to determine metabolic activity? Acid production from fermentation CO2 produced from the Krebs cycle NO2- produced from the electron transport chain Decreased dissolved oxygen Turbidity

Turbidity

The term facultative anaerobe refers to an organism that.. Doesn't use oxygen but tolerates it. Is killed by oxygen. Uses oxygen or grows without oxygen. Requires less oxygen than is present in air. Prefers to grow without oxygen.

Uses oxygen or grows without oxygen

Which of the following pairs is mismatched? Ag - burns Alcohols - open wounds CuSO4 - algicide H2O2 - open wounds Organic acids - food preservation

alcohols open wounds

Which of the following substances can sterilize? Alcohol Phenolics Ethylene oxide Chlorine Soap

ethylene oxide

Which of the following will NOT preserve foods? Desiccation High pressure Ionizing radiation Microwaves Osmotic pressure

microwaves