Thursday, March 1, 2001

Midterm Exam #3

Microbiology 509

Name: _____________________________________

 

Œ   Place your name at the top of each page.

   There are 37 questions

Ž   Each question is worth the same amount

   Remember: distinguish compared items by linking descriptions to terms (e.g., the sky isblue).

   Unless requested, do not multiply out expressions (e.g., stop at 2*5003 rather than 2.5x108).

‘   I encourage you to ask questions during the exam, but do so discretely.

’   Remember to use safe, i.e., unambiguous & well-articulated answers whenever possible.

“     Above all, avoid jumping to profoundly incorrect conclusions: make sure you actually read a question (all of it) before you answer, and then make sure you are actually answering what it is you are being asked.

 

(1) __________ is a name for the general category of human diseases that possess animal reservoirs.

 

 

A: zoonosis

(2) Antibiotics that bind to the bacterial ribosome, but not the eucaryote ribosome, interfere with bacterial metabolism by inhibiting _________ synthesis (i.e., the normal catalytic function of both bacterial and eucaryotic ribosomes).

 

A: protein (chapter 13)

(3) Contamination is the converse of __________ while infection is the actual growth of pathogens in or on body tissues.

A: Sterility (chapter 14)

(4) During which stage of an illness would you expect the body would contain the most living pathogenic organisms?

(i) Acme

(ii) Convalescence

(iii) Incubation

(iv) Prodromal

(v) Sequelae

A: (i) Acme (chapter 14)

(5) For an antibiotic, which is typically higher:

(i) Dosage achieved when prescription is prematurely terminated

(ii) Dosage that more likely promotes the development of resistance

(iii) Minimum inhibitory concentration

(iv) Therapeutic dosage level

(v) Toxic dosage level

A: (v) Toxic dosage level (chapter 13)

(6) Glutaraldehyde, formaldehyde, and ethylene oxide are all examples of disinfectants that work by acting as __________ agents.

(i) Alkylating

(ii) Halogenating

(iii) Inducing

(iv) Oxidizing

(v) Reducing

A: (i) Alkylating (chapter 12)

(7) If bacteria normally mutate to antibiotic resistance at a rate of 1 in 100 million (i.e., 1 / 108), per antibiotic, then a bacteria population exposed to two independently acting antibiotics would have to be what size before we would expect the population to contain a bacterium that is simultaneously resistant to both antibiotics?

(i)                  108 bacteria

(ii)                1064 bacteria

(iii)               8 bacteria

(iv)              16 bacteria

(v)                104 bacteria

(vi)              1016 bacteria

A: (vi) 108 x 108 = 1016 (chapter 13)

(8) Important for preventing transmission of pathogens in clinical settings are aseptic technique, the employment of barriers, introspection, good management, and __________.

 

A: hand washing (chapter 15)

(9) In which general category of symbiosis is one member (of the symbiosis) considered neither harmed nor benefited?

 

A: Commensalisms (chapter 14)

(10) Indirect contact transmission occurs via the handling of _________. (which is a general term rather than specific items such as dirty linens, e.g., sheets)

 

A: fomites (chapter 15)

(11) Mechanisms of disinfection often include protein denaturation, membrane disruption, inhibition of metabolism, and __________.

 

A: Nucleic acid damage (chapter 12)

(12) Mutation-mediated resistance is particularly associated with:

(i) Acquired resistance

(ii) Evasion

(iii) Inactivation of antibiotic by hydrolysis

(iv) ß-lactamase

(v) The bacterial chromosome

A: (v) The bacterial chromosome (chapter 13)

(13) Name a vehicle and corresponding portal of entry.

 

 

 

A: air/respiratory tract, water/gastrointestinal tract, food/gastrointestinal tract (chapter 15)

(14) Name two halogens.

 

 

 

A: Iodine, chlorine, bromine (chapter 12)

(15) Organisms in what phase of growth in the standard bacterial growth curve typically are the most susceptible to disinfection?

 

A: Exponential (chapter 12)

(16) Staphylococcal food poisoning is caused by __________ (circle best answer)

(i) an enterotoxin

(ii) a neurotoxin

(iii) a microtoxin

(iv) Staphylococcus aureus infection

(v) all of the above

(vi) none of the above

A: (i) an enterotoxin (chapter 14)

(17) Tetracycline

(i) Acts at the bacterial ribosome

(ii) Disrupts cell membranes

(iii) Inhibits cell-wall synthesis

(iv) Is a ß-lamtam antibiotic

(v) Is effective against herpes infections

A: (i) Acts at the bacterial ribosome (chapter 13)

(18) The charge associated with an ionized quat is

(i) Both positive and negative

(ii) Sometimes positive, sometimes negative

(iii) Negative

(iv) Positive

(v) Nonexistent

A: (v) Positive (hense, quats are cationic detergents (chapter 12)

(19) The route through which a pathogen enters our bodies is called its __________ of entry.

 

A: portal (chapter 15)

(20) The Universal Precautions were initially developed specifically to prevent the transmission of what general category of pathogens?

 

A: blood-borne pathogens (chapter 15)

(21) What does "synergism" (or "synergy") mean?

 

 

 

 

 

 

 

 

A: Synergy is a greater than the sum of the parts phenomenon, i.e., a bigger effect than expected given knowledge of the performance of the individual components of a system (chapter 13)

(22) What is meant when an antibiotic is described as being selectively toxic?

 

 

 

 

 

 

 

 

A: The antibiotic has a lower toxicity against the host than it does against the microbial pathogen (chapter 13)

(23) What is microbial competition (a.k.a., microbial antagonism)?

 

 

 

 

 

 

 

A: Microbial competition is when the presence (and/or growth) of one microorganisms presents the colonization by a second microorganisms, thereby preventing infection and disease if the second microorganism is a pathogen (chapter 14)

(24) What is the cleanliness effect in the disinfection of, for example, surfaces?

 

 

 

 

 

 

 

 

A: Since microbes die exponentially, the more microbes that must be killed, the longer it will take to kill the microbes; consequently, to enhance the killing power of a given method one can simply reduce the number of microbes present prior to application, such as one achieves during the simple cleaning of an object (chapter 12)

(25) What is the difference between a propagated epidemic and an epidemic (outbreak) that has a common source?

 

 

 

 

 

 

A: A propagated epidemic is passed from individual to individual so has many sources (places/individuals from which the infection may be acquired) whereas a common source outbreak has only a very limited reservoir from which infection may be acquired (chapter 15)

(26) What is the minimum temperature one normally applies dry heat to sterilize something?

 

A: 121°C (chapter 12)

(27) What is the mode of antibiotic action displayed by cephalosporin?

 

A: disruption of cell-wall synthesis (chapter 13)

(28) What is vertical transmission?

 

 

 

 

A: vertical transmission is transmission from parent to child (chapter 15)

(29) What properties must a substance possess to be considered a surfactant?

 

 

 

A: The substance must have both a hydrophobic and an hydrophic portion such that is dissolves both lipids and dissolves into water (chapter 12)

(30) What property (as opposed to location of use) distinguishes antiseptics from disinfectants?

 

 

A: Antiseptics generally are less harsh (especially to living flesh) than disinfectants (chapter 12)

(31) Which are more likely to lead to superinfections?

(i) Acyclovir

(ii) Antifungals

(iii) Broad-spectrum antibiotics

(iv) Narrow spectrum antibiotics

(v) Semisynthetic drugs

A: (iii) Broad-spectrum antibiotics (chapter 13)

(32) Which has the greatest likelihood of being the most pathogenic of the following?

(i) A fully attenuated pathogen

(ii) Commensals (and not opportunists)

(iii) Indigenous microflora (and not opportunists)

(iv) Non-communicable pathogens

(v) Organisms with a virulence of zero

A: (iv) Non-communicable pathogens (communicability says nothing about pathogenicity, e.g., anthrax) (chapter 14)

(33) Which is not a category of disease?

(i) Acute

(ii) Focal

(iii) Inapparent

(iv) Septicemia

(v) Toxoid

A: Toxoid (chapter 14)

(34) Which is not an exotoxin, derived from an exotoxin, or a disease that results from an exotoxin?

(i) Botulism

(ii) Enterotoxin

(iii) Lipopolysaccharide

(iv) Neurotoxin

(v) Tetanous toxoid

A: Lipopolysaccharide (chapter 14)

(35) Which is not typically involved in an infection

(i) Adherence

(ii) Colonization

(iii) Contact

(iv) Invasion

(v) Toxoid

A: (v) Toxoid (chapter 14)

(36) Which is of least concern as an etiology of nosocomical infections?

i) Campylobacter

(ii) Escherichia

(iii) Enterococcus

(iv) Pseudomonas

(v) Staphylococcus

A: (i) Campylobacter (chapter 15)

(37) Which method of bacteria preservation is listed twice? (circle both)

(i) Desiccation

(ii) Freeze drying

(iii) Freezing

(iv) lyophilization

(v) Refrigeration

A: (ii) Freeze drying / (iv) lyophilization (I'll also accept dessication as one of the pair) (chapter 12)