Farmer Brown is a 65-year-old white male. He has just retired, sold his farm and moved into a condo in Gainesville. He comes to the Shands clinic for treatment for a cough. He tells you that he has been bothered by coughing for about 15 years. The country doctor he used to go to said he had chronic bronchitis and would give him penicillin or "some other drug" each time his bronchitis flared up. Sometimes if he didn't have time to go to the doctor he would take some of the medicine that he gave his cows for "scours" and this seemed to help, too. He had read the label on the cow medicine and recognized that it contained a drug that had been prescribed for one of his bouts of bronchitis. He was a chain smoker, having tried to give it up unsuccessfully no less than 5 times. You tell him that you want to diagnose the cause of his cough, not just give him a drug that may or may not work. He gets upset and leaves, telling you he'll find a doctor that will give him some medicine.
Question 1 - Single Best Answer
The "root" cause of most cases of chronic bronchitis is thought to be? Bugs Database
A) bacteria
B) viruses
C) fungi
D) smoking
Question 2 - Single Best Answer
The cause of most exacerbations of chronic bronchitis is thought to be? Bugs Database
A) bacteria
B) viruses
C) fungi
D) cold weather
Question 3 - Single Best Answer
The penicillin will reduce the duration and the severity of a viral infection, although it won't cure it? Bugs Database
A) true
B) false
Question 4 - Single Best Answer
Reducing the number of cigarettes smoked will have no effect on bronchitis. The patient must give up smoking altogether? Bugs Database
A) true
B) false
Mr. Brown came back the next day. His cough was much worse, and the sputum had changed color. It was now somewhat "rusty." He said he had a chill yesterday, and then developed a fever of 103. He said he had gone to the feed store and taken some of the cow medicine but that it had just made it worse. You note that he looks quite ill. His lips and nail beds are slightly cyanotic and you hear fine inspiratory rales over the right lateral chest.
Question 5 - Single Best Answer
These changes indicate that Mr. Brown may have? Bugs Database
A) TB
B) pneumonia
C) an exacerbation of his chronic bronchitis
D) whooping cough
E) lung cancer from his smoking
A Gram stain of the sputum shows a number of Gram positive cocci in pairs and many polymorphonuclear leukocytes. A chest x-ray shows consolidation of the right lower lobe.
Question 6 - Single Best Answer
Do the Gram positive diplococci in sputum always mean pneumonia? Bugs Database
A) yes
B) no
Question 7 - Single Best Answer
Which of the following infectious agents is the likely cause of Mr. Brown's disease? Bugs Database
A) Mycoplasma pneumonia
B) Mycobacterium tuberculosis
C) Influenza virus
D) Streptococcus pneumonia
E) Klebsiella pneumonia
You admit Mr. Brown to the hospital and start him on penicillin immediately. You also draw blood for a CBC and blood culture and request that antibiotic sensitivity testing be done on any organisms isolated from the blood culture.
Question 8 - Single Best Answer
The lab reports an "alpha" strep in the blood culture. Does this, coupled with what you saw in the Gram stain of the sputum, positively identify Streptococcus pneumoniae? Bugs Database
A) yes
B) no
Question 9 - Single Best Answer
Later, it is reported that the organism in the blood culture is alpha hemolytic, catalase negative, and optichin sensitive. This organism can be positively identified as? Bugs Database
A) Streptococcus pneumonia
B) Streptococcus pyogenes
C) Staphylococcus aureus
D) Staphylococcus epidermidis
E) Staphylococcus saprophyticus
Farmer Brown got progressively worse in spite of the penicillin. He was started on ceftriaxone on the second hospital day, and when he still did not improve, rifamycin was added. He died on the 3rd hospital day. Antibiotic sensitivity testing on the S. pneumoniae from his blood culture revealed that it was resistant to seven different antibiotics.
Question 10 - Single Best Answer
Mechanisms by which bacteria can become resistant to antibiotics include? Bugs Database
A) an alteration in the target of the antibiotic
B) the production of an enzyme that breaks down the antibiotic
C) a mechanism to pump the antibiotic out of the bacterial cell
D) A and B above
E) all of the above
Question 11 - Single Best Answer
When the mechanism of resistance is the production of an enzyme that can destroy the antibiotic, the genetic information for the enzyme is most likely to be found? Bugs Database
A) in the mitochondrial DNA
B) on a plasmid
C) on the bacterial chromosome
D) one cannot tell from the type of resistance where the gene is likely to be found
Question 12 - Single Best Answer
The enzyme, beta lactamase, causes antibiotic resistance by destroying the active site of which of the following antibiotics? Bugs Database
A) tetracycline
B) streptomycin
C) sulfonamides
D) rifampin
E) penicillin
Question 13 - Single Best Answer
If resistance to an antibiotic occurs because of an alteration in the target of the antibiotic, the resistance will likely map to a gene on? Bugs Database
A) the chromosome
B) a lysogenized phage
C) an integrated plasmid
D) an autonomous plasmid
Question 14 - Single Best Answer
In the case of penicillin resistance in Streptococcus pneumonia, the mechanism is most likely? Bugs Database
A) a plasmid carrying an enzyme (beta lactamase) that destroys the penicillin.
B) a chromosomal mutation producing beta lactamase.
C) a chromosomal mutation in a penicillin binding protein (PBP) in the cell wall.
D) a change in the RNA polymerase causing changes in the peptidoglycan.
Question 15 - Single Best Answer
A mutation that altered the structure of bacterial RNA polymerase could cause resistance to which of the following? Bugs Database
A) tetracycline
B) streptomycin
C) sulfonamides
D) rifampin
E) penicillin
Question 16 - Single Best Answer
For a population of bacteria to become resistant to antibiotics, they need some kind of change in their genotype plus? Bugs Database
A) selection
B) mutation
C) conjugation
D) transformation
E) transduction
Question 17 - Single Best Answer
A change in an organism's genotype can occur in two general ways. These are? Bugs Database
A) selection and mutation
B) transposition and mutation
C) genetic exchange and selection
D) recombination and transposition
E) genetic exchange (acquiring new genetic information from another source) and mutation
Question 18 - Single Best Answer
Genetic exchange (acquiring new genetic information from another source) and mutation are two ways in which a bacterium can change its genotype. What are the mechanisms of genetic exchange in bacteria? Bugs Database
A) transformation
B) conjugation
C) transduction
D) all of the above
E) none of the above
New genetic information is only half of the equation in antibiotic resistance. The other half is selection. This usually means that certain individuals are better able to survive under some (usually) adverse conditions. For example, under very high temperatures most organisms will die. If a mutation occurs so that some can live in the high temperatures, these will be selected for. In this case, the selective pressure is the temperature. If most bacteria die in the presence of an antibiotic but a few (resistant ones) don't, the resistance ones are said to have been selected for.
Question 19 - Single Best Answer
In the case of antibiotic resistance, what is providing the selective pressure? Bugs Database
A) temperature
B) lack of nutrients
C) the antibiotic
D) mutation
E) transposition
Question 20 - Single Best Answer
In the case of Farmer Brown, where did the antibiotics come from that selected his resistant organisms? Bugs Database
A) his doctors
B) his self medication
C) the meat from his antibiotic treated cows
D) A and B above
E) all of the above
Question 21 - Single Best Answer
Had Farmer Brown not died, what would have been the next antibiotic to try? Bugs Database
A) metronidazole
B) isoniazid
C) vancomycin
D) tetracycline
E) aminoglycoside
Streptococcus pneumoniae is a little unusual in that most of its antibiotic resistance comes from a gradual build-up of mutations that change the targets of the antibiotics. It is thought that these mutations arose in countries where antibiotics can be freely purchased and that the mutated bacteria are being spread around the world by asymptomatic carriers. This type of antibiotic resistance is harder to develop, but also harder to get rid of than plasmid mediated resistance which is the commonest type of resistance in Gram negatives, i.e., E. coli. Plasmids that contain genes for resistance to many different antibiotics can be passed from bacteria to bacteria. If a plasmid carries resistance to, say, ten antibiotics, all those will be selected for by only one of the antibiotics! The development of antibiotic resistance in the Gram negatives is thought to be exacerbated by the use of antibiotics in animal feed, but this is not the only cause. The medical profession must shoulder some of the blame as well.
Question 22 - Single Best Answer
What are some things that can be done to help with the problem of antibiotic resistance? Bugs Database
A) judicious use of antibiotics by doctors
B) allowing the use of only certain antibiotics in animal feed
C) developing new types of antibiotics that cannot be modified by known enzymes
D) all of the above