Microbiology Chapter 8

How many bacteria were scanned in an effort to find those with the mcr-1 gene? 55 5.5 x 103 105 5.5 million 55 x 103

55 x 103

Acinetobacter baumannii may have acquired resistance to multiple antibiotics through transformation. conjugation transduction None of the choices are correct. All of the choices are correct.

All of the choices are correct.

A test that screens for potential carcinogens by measuring the ability of a substance to increase the mutation frequency in a bacterial strain.

Ames test

Mechanism of horizontal gene transfer in which the bacterial DNA is transferred as "naked" DNA.

Bacterial transformation

Initially, the patient was infected with methicillin-resistant S. aureus. Which of the following was/ were found in her foot ulcer after she received vancomycin for this first infection? Only vancomycin-resistant S. aureus. Only penicillin-resistant S. aureus. Only vancomycin-resistant E. faecalis. Only methicillin-resistant E. faecalis.

Both VRE and VRSA.

Donor bacterial cell in conjugation that transfers the F plasmid.

F + cell

Recipient bacterial cell in conjugation that lacks an F plasmid.

F - cell

A protein appendage used for DNA transfer in the process of conjugation.

F pilus (sex pilus)

Plasmid found in donor cells of Escherichia coli that codes for the F or sex pilus and makes the cell F+.

F plasmid

An altered F plasmid that contains a chromosomal fragment; results from an incorrect excision of an F plasmid that was integrated into the chromosome.

F'

A. baumannii is easily removed from hospital surfaces by disinfectants. T/F

False

Nosocomial infections caused by A. baumannii in civilian hospitals are not a major concern. T/F

False

Review the chart showing hypothetical data for a similar case. The purple line represents VRSA. The orange line shows VSSA (vancomycin-sensitive S. aureus). A concentration of greater than 0.02 mg/mL of vancomycin is sufficient to inhibit the growth of VRSA. T/F

False

The patient's bacteremia was caused by VRSA. T/F

False

Cells that have the F plasmid integrated into their chromosome, allowing them to begin transferring the chromosome by conjugation; stands for "high frequency of recombination cells".

Hfr cells

Which word in the report means looking back at past events or situations? Porcine Carbapenem Bovine Retrospective Retroactive

Retrospective

Complex, inducible, and error-prone process used to repair highly damaged DNA.

SOS repair

In horizontal gene transfer, physiological condition in which a bacterial cell is capable of taking up DNA.

competent

Mechanism of horizontal gene transfer in which the donor cell physically contacts the recipient cell.

conjugation

Because all of the genes coding for antibiotic resistance have been found to come from other organisms, A. baumannii most likely acquired them through mutation and evolution of its own genome. transcription and transformation. conjugation or a similar process of genetic exchange. transcription and translation. All of the choices are correct.

conjugation or a similar process of genetic exchange.

DNA sequences found in all strains of a particular species.

core genome

Technique of selecting mutants by plating organisms on a medium on which the desired mutants but not the parent will grow.

direct selection

Mutation resulting from the addition or deletion of a number of nucleotides not divisible by 3.

frameshift mutation

Type of horizontal gene transfer that can occur when a phage carries a random piece of bacterial DNA; the phage acquires that DNA when a packaging error occurs during the assembly of phage particles.

generalized transduction

Large segment of DNA acquired from another species through horizontal gene transfer; an example is a pathogenicity island.

genomic island

The sequence of nucleotides in an organism's DNA.

genotype

DNA transfer from one organism to another by a process other than reproduction; in bacteria, this occurs by bacterial transformation, conjugation, or transduction.

horizontal gene transfer (HGT)

In microbial genetics, a technique for isolating mutants and identifying organisms unable to grow on a medium on which the parents do grow; often involves replica plating.

indirect selection

Mutation that results from treatment of an organism with an agent that alters its DNA.

induced mutation

A method for indirect selection that involves the simultaneous transfer of organisms in separated colonies from one medium to another.

replica plating

Bacterial system that uses restriction enzymes to defend against invading foreign DNA; modification enzymes methylate the host DNA to protect it.

restriction-modification system

Acinetobacter baumannii is a common resident of ______. soil and water certain foods the skin respiratory secretions fecal material

soil and water

Infections caused by A. baumannii have most frequently been seen in the elderly. patients with heart disease. women. newborn babies. soldiers at military hospitals.

soldiers at military hospitals.

Type of horizontal gene transfer that can occur when a temperate phage carries specific bacterial genes; the phage acquires those genes when an error occurs as the prophage excises from a lysogenic cell's chromosome.

specialized transduction

Mutation that occurs naturally during the course of normal cell processes.

spontaneous mutation

A mutation that does not change the amino acid encoded.

synonymous mutation

Two adjacent thymine molecules on the same strand of DNA joined together through covalent bonds.

thymine dimer

Mechanism of horizontal gene transfer in which bacterial DNA is transferred inside a phage coat.

transduction

Segment of DNA that can move from one site to another in a cell's genome.

transposon

Review the chart showing hypothetical data for a similar case. The purple line represents VRSA. The orange line shows VSSA (vancomycin-sensitive S. aureus). At what dose of vancomycin is the VSSA population reduced by approximately two thirds? 0.002mg/mL 22 micrograms 4 days. 2 mg/mL 0.004 mg/mL

0.002mg/mL

Which of the following are true about CRISPR? 1 CRISPR loci can reveal a historical record of phage infections of a bacterial cell. 2 CRISPR systems act as a barrier to horizontal gene transfer. 3 The CRISPR system is limited to protecting bacteria against phage infection. 4 CRISPR systems act as a barrier to vertical gene transfer. 5 There are several versions of the CRISPR system that all function differently.

1, 2

Which of the following are antibiotics or types of antibiotics mentioned in the study? 1 Colistin 2 Penicillin 3 Carbapenem 4 Polymyxin E 5 Aspirin 6 Gentamicin

1, 2, 3, 4

Select the TRUE statements regarding E. coli that you learned from this report. 1 It is Gram-negative. 2 It is Gram-positive. 3 It can cause urinary tract infections. 4 It is resistant to all antibiotics. 5 It can cause neurological damage.

1, 3

Why isn't colistin used very often to treat infections? Check all the correct choices. 1 It can cause serious kidney damage. 2 It is not an effective antibiotic. 3 Colistin is an old antibiotic. 4 It can cause nervous system problems. 5 It is too expensive.

1, 4

What is the likely way other bacteria might acquire the mcr-1 gene? Plasmid UV irradiation Conjugation Transduction Transformation

Conjugation

How might the MRSA strain become resistant to vancomycin? Resistance to methicillin also confers resistance to vancomycin. The MRSA strain acquired plasmid A and thus vancomycin resistance from the E. faecalis. The MRSA strain acquired plasmid B and thus vancomycin resistance from the E. faecalis. The transposon with the vancomycin resistance gene "jumped" from the E. faecalis into the MRSA plasmid. The transposon from the methicillin-resistant S. aureus "jumped" into the VRE plasmid.

The transposon with the vancomycin resistance gene "jumped" from the E. faecalis into the MRSA plasmid.

Which of the following is an acronym for a type of infection given in the report? mrc-1 E. coli MDR UTI NARMS

UTI

Review the chart showing hypothetical data for a similar case. The purple line represents VRSA. The orange line shows VSSA (vancomycin-sensitive S. aureus). After how many days of vancomycin treatment is VSSA completely eliminated? 20 days 9 days 4 days We are not given this information.

We are not given this information.

A "nosocomial" infection is an infection acquired through contaminated air. food and water. a hospital stay. contaminated needles. sexual intercourse.

a hospital stay.

Based upon information in Chapter 8 and the case study, it appears that multidrug resistant strains of bacteria such as A. baumannii: only need to be sampled and tested for within military hospitals. acquired their resistance genes from other bacteria in healthcare facilities. can only be treated with antiviral or antifungal medications. have resistance genes that are different from other bacteria seen commonly in healthcare facilities. only undergo conjugation as a means of genetic transfer.

acquired their resistance genes from other bacteria in healthcare facilities.

A microorganism that requires an organic growth factor.

auxotroph

Compound that structurally resembles a nucleobase closely enough to be incorporated into a nucleotide in place of the natural nucleobase.

base analog

A mechanism cells use to remove damaged nucleobases in DNA and then repair the region of damage.

base excision repair

A mutation in which the wrong nucleotide has been incorporated.

base substitution

Agents that insert between base pairs in a DNA double helix.

intercalating agents

Repair mechanism in which an enzyme cuts the DNA near a mismatched nucleobase, resulting in the removal and replacement of a short stretch of nucleotides.

mismatch repair

A mutation that changes the amino acid encoded by DNA.

missense mutation

Segments of DNA that can move from one DNA molecule to another.

mobile genetic elements (MGEs)

Any agent that increases the frequency at which DNA is altered (mutated).

mutagen

A change in the nucleotide sequence of a cell's DNA that is passed on to daughter cells.

mutation

A mutation that generates a stop codon, resulting in a shortened protein.

nonsense mutation

Mechanism of DNA repair in which a fragment of single-stranded DNA that contains mismatched bases is removed and replaced; also called dark repair.

nucleotide excision repair

Method for increasing the relative proportion of auxotrophic mutants in a population by using penicillin to kill growing prototrophic cells.

penicillin enrichment

The observed characteristics of a cell.

phenotype

Mechanism of DNA repair that uses the energy of light to break the covalent bonds joining thymine dimers, thereby restoring the DNA to its original state; also called light repair.

photoreactivation

Extrachromosomal DNA molecule that replicates independently of the chromosome.

plasmid

The S. aureus methicillin resistance gene occurred on ______, while the E. faecalis vancomycin resistance gene occurred on ______. plasmid A; a transposon plasmid B; a transposon a transposon; plasmid A a transposon; plasmid B plasmid A; plasmid B

plasmid A; a transposon

The detection and removal by DNA polymerase of an incorrect nucleotide incorporated as DNA is synthesized.

proofreading

A microorganism that does not require any organic growth factors.

prototroph