MULTIPLE CHOICE
1. What is a biofilm?
a. Communities of organisms attached to a solid surface
b. The resulting thick, slimy mucous produced in cystic fibrosis
c. A slime factor that can be found in your gastrointe
...
MULTIPLE CHOICE
1. What is a biofilm?
a. Communities of organisms attached to a solid surface
b. The resulting thick, slimy mucous produced in cystic fibrosis
c. A slime factor that can be found in your gastrointestinal tract
d. The resulting film that is produced by necrotic tissue, bacteria, and immune cells
A
Biofilms are communities of microorganisms attached to a solid surface; the surface can be either abiotic (nonliving) or living tissue.
REF: 753 OBJ: Level 1: Recall
2. Cobiofilms of what two organisms are associated with serious lung infections in cystic fibrosis patients?
a. Pseudomonas aeruginosa and Moraxella
b. Pseudomonas aeruginosa and Burkholderia cepacia
c. Pseudomonas aeruginosa and Mycobacterium tuberculosis
d. Pseudomonas aeruginosa and Streptococcus pneumoniae
B
Cobiofilms of Pseudomonas aeruginosa and Burkholderia cepacia are associated with serious lung infections in patients with cystic fibrosis.
REF: 753 OBJ: Level 1: Recall
3. What is a sessile-type biofilm?
a. A biofilm made up of free-floating microorganisms
b. A multiple-species biofilm
c. A biofilm that is attached and made up of multiple species
d. A biofilm that is present in an aquatic environment
C
The sessile phenotype results from attachment and usually develops into a multispecies biofilm that has unique characteristics, making it similar in many ways to hydrated polymers.
REF: 753 OBJ: Level 1: Recall
4. Biofilms are a universal strategy for:
a. planktonic free-floating organisms.
b. increasing plasmid transfer for antibiotic resistance.
c. battle sheer forces.
d. survival, horizontal gene transfer, and growth.
D
Biofilms are a universal strategy for survival, horizontal gene transfer, and growth, and a probable ancestor of the planktonic free-floating organisms.
REF: 754 OBJ: Level 1: Recall
5. All of the following environmental and key cultural characteristics affect biofilms except:
a. movement of host.
b. genotypic factors.
c. nutritional resources.
d. mechanical factors and sheer forces.
A
Several key environmental and cultural characteristics affect the selection of multispecies biofilm inhabitants. These features include species attachment efficiency, genotypic factors, cyclic stage of biofilm, substrata, nutritional resources, mechanical factors and sheer forces, physicochemical environment, and antiinfective hostile pressure forces.
REF: 754 OBJ: Level 1: Recall
6. All of the following organisms are very efficient at converting from planktonic to biofilm biotypes when environmental stresses hit except:
a. Coagulase-negative staphylococci.
b. Pseudomonas aeruginosa.
c. Micrococcus luteus.
d. Candida albicans.
C
It is not by accident that coagulase-negative staphylococci, P. aeruginosa, and C. albicans are some of the most efficient and upregulated prone microbes when selective pressures magnify the need to survive in a biofilm community. These microorganisms are also important human pathogens.
REF: 754 OBJ: Level 1: Recall
7. What is stage I of biofilm development?
a. Multiplication phase
b. Irreversible binding phase
c. Layering phase
d. Attachment phase
D
Stage I is the attachment phase that can take only seconds to initiate and is likely induced by environmental signals.
REF: 754 OBJ: Level 1: Recall
8. What is stage II of biofilm development?
a. Irreversible binding phase
b. Multiplication phase
c. Attachment phase
d. Layering phase
A
Stage II is characterized as irreversible binding and begins minutes after stage I (attachment). During stage II, cell aggregates are formed and motility is decreased. Toward the end of this stage, exopolysaccharide is produced that is able to trap nutrients and planktonic bacteria.
REF: 755 OBJ: Level 1: Recall
9. What is stage III of biofilm development?
a. Irreversible binding phase
b. Layering phase
c. Attachment phase
d. Multiplication phase
B
When cell aggregates become progressively layered, with a thickness greater than 10 m, the biofilm is in stage III. This stage is also referred to as maturation-1.
REF: 755 OBJ: Level 1: Recall
10. What is stage IV of biofilm development?
a. Multiplication phase
b. Thickening phase
c. Cell dispersion
d. Planktonic stage
B
When biofilms reach their ultimate thickness, generally greater than 100 m, this is referred to as stage IV or maturation-2. It takes a biofilm several days to reach this stage.
REF: 755 OBJ: Level 1: Recall
11. What is stage V of biofilm development?
a. Spreading phase
b. Multiplication phase
c. Cell dispersion
d. Layering phase
C
During stage V, cell dispersion is noted. Some of the bacteria develop the planktonic phenotype and leave the biofilm.
REF: 755 OBJ: Level 1: Recall
12. What are the metabolically inert microorganisms present in a biofilm called?
a. Spores
b. Pheromone cells
c. Quorum sensing cells
d. Persister cells
D
Persister cells, essentially metabolically inert microorganisms analogous to bacterial spores, are present in all biofilms and bacterial populations. Persister cells are hypothesized to have disabled programmed cell death or apoptosis. These cells have the greatest potential for maintenance of the gene pool and resistance to environmental stress, including antimicrobial agents.
REF: 755 OBJ: Level 1: Recall
13. This layer of a biofilm is exposed to the highest concentration of nutrients and oxygen, containing the most active organisms. What layer is this?
a. Outer
b. Inner
c. Middle
d. Substrata
A
The outermost layer of a biofilm is exposed to the highest concentration of nutrients and oxygen. It contains the most active organisms that primarily resemble the structure and activity of their planktonic counterparts.
REF: 755 OBJ: Level 1: Recall
14. In what level of the biofilm do the organisms slightly downregulate their metabolic activity, but still use nutrients and exchange genes?
a. Outer
b. Intermediate
c. Inner
d. Substrata
B
The second layer of the architecture is an intermediate level. Organisms in the second layer downregulate somewhat in their metabolic activity, but they clearly have the capacity to use nutrients, exchange genes, and have the potential for multiple drug resistance. This spatial arrangement, physiologic heterogeneity, and nonuniformity are based on the proximity of microorganisms aligning next to one another.
REF: 756 OBJ: Level 2: Interpretation
15. In what level of the biofilm do the organisms downregulate very efficiently and are the least metabolically active?
a. Outer
b. Intermediate
c. Inner
d. Substrata
C
The innermost layer of cells is attached to the substratum and represents the earliest part of the biofilm. These microorganisms also downregulate very efficiently and are the least metabolically active. This is where most of the persister cells are located.
REF: 756 OBJ: Level 2: Interpretation
16. In which step of the infectious process could biofilms help bacteria when it comes to developing colonization of indwelling medical devices?
a. Downregulation
b. Phenotypic variation
c. Genotypic variation
d. Attachment
D
Colonization is often an important first step in infectious disease, and biofilms may be an important mechanism of attachment to host tissue and indwelling medical devices.
REF: 756 OBJ: Level 2: Interpretation
17. What do biofilms allow members of the microbial community to do?
a. Withstand the shear forces of blood and urine
b. Remain in a nutrient rich environment
c. Survive
d. All of the above
D
Biofilms allow members of the microbial community to withstand the shear forces of blood and urine flow, presumably keeping the microorganisms in a nutrient-rich environment.
REF: 757 OBJ: Level 1: Recall
18. Biofilms can protect its members from all of the following except:
a. antibodies.
b. oxygen-reactive molecules.
c. antimicrobial drugs.
d. phagocytosis.
A
Biofilms can afford protection from host defenses including oxygen reactive molecules, antimicrobial proteins, antimicrobial drugs, and phagocytosis. In addition, biofilms protect against pH changes and nutrient deprivation.
REF: 757 OBJ: Level 1: Recall
19. How do microorganisms that live in close proximity exchange DNA?
a. Frame-shift mutations and plasmid uptake
b. Transformation and conjugation
c. Conjugation and frame-shift mutations
d. All of the above
B
The biofilm is an optimal environment for the horizontal transfer for DNA. The microorganisms live in close proximity, which facilitates the uptake of DNA by transformation and conjugation.
REF: 757 OBJ: Level 1: Recall
20. What process allows the bacteria of the biofilm to spread to other body sites?
a. Conjugation
b. Metastasis
c. Disaggregation
d. Planktonization
C
Disaggregation or detachment of aggregates clearly has the potential of transmitting already upregulated aggregates of microorganisms to other body sites. Similar to cancer metastasis, this is most significant when aggregates spread via the bloodstream. This provides the microorganisms an opportunity to reach almost any body site.
REF: 758 OBJ: Level 1: Recall
21. What is the common name for a dental biofilm?
a. Cavity
b. Gingivitis
c. Periodontitis
d. Plaque
D
Dental biofilms, more commonly called plaque, are probably the most well-studied natural biofilm in humans. The microorganisms making up a dental biofilm are considered normal flora of the oral cavity.
REF: 758 OBJ: Level 1: Recall
22. The late colonizers in the dental biofilm include all the following except:
a. Capnocytophaga.
b. Streptococcus salivarius.
c. Selenomonas flueggei.
d. Prevotella spp.
A
The late colonizers forming aggregates with the fusobacteria in dental biofilms include Streptococcus salivarius, Propionibacteria, Prevotella, Veillonella, and Selenomonas flueggei.
REF: 759 OBJ: Level 1: Recall
23. What happens to dental plaque if it is allowed to remain undisturbed for several days?
a. The biofilm disaggregates.
b. The persister cells predominate the biofilm.
c. Pathogenic bacteria become the main bacterial constituents of the biofilm.
d. Nonpathogenic bacteria become the main bacterial constituents of the biofilm.
C
If the plaque is allowed to remain undisturbed on the teeth for several days, the microbial flora continues to change and becomes composed mainly of anaerobic and facultative anaerobic gram-negative bacilli and spirochetes. The last colonizers of the biofilm are considered pathogenic because of their role in periodontal disease.
REF: 759 OBJ: Level 1: Recall
24. What disease, caused by biofilms, consumes more resources in the intensive care unit (ICU) than any other infectious disease?
a. Blood cultures positive with coagulase-negative staphylococci
b. Urinary tract infections due to gram-negative rods
c. Surgical site infections
d. Ventilator-associated pneumonia
D
Ventilator-associated pneumonia, a condition that consumes more resources in the ICU than any single infectious disease, is another example in which biofilms are an important disease-contributing factor.
REF: 760 OBJ: Level 1: Recall
25. All the following are laboratory-associated problems related to identifying biofilm-associated diseases except:
a. false-positive cultures.
b. false-negative cultures.
c. viable but noncultural organisms.
d. loss of or decreased antimicrobial susceptibility.
A
The emergence of biofilm-associated diseases causes considerable diagnostic problems for the clinical laboratory. In general, these problems can be classified into five categories: false-negative cultures, viable but nonculturable organisms, underestimated or low colony count, inappropriate specimens, and loss of or decreased antimicrobial susceptibility.
REF: 760 OBJ: Level 1: Recall
26. What types of cells in a biofilm are viable but nonculturable?
a. Phagocytes
b. Persister
c. Attachment cells
d. Layering cells
B
Some persister cells found in biofilms are viable but nonculturable bacteria.
REF: 760 OBJ: Level 1: Recall
27. Treating infectious diseases has shifted from planktonic susceptibility profiles to:
a. therapeutic modalities.
b. creative treatments.
c. multiple interventions.
d. degrading enzymes.
C
Because of the physical and chemical properties of biofilms, traditional antimicrobial therapy based on planktonic susceptibility profiles will have limited impact on resilient multispecies biofilms. Therapeutic modalities are refocusing on multiple interventions, recognizing that properties of biofilms are similar to organic polymers and not planktonic microbes.
REF: 761 OBJ: Level 1: Recall
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