The quizzes about Antimicrobial and Antiviral Pharmacology - Part 1

I. Start the exam by click the “Start” button

Antimicrobial and Antiviral Pharmacology- Part 1

Please wait while the activity loads.
If this activity does not load, try refreshing your browser. Also, this page requires javascript. Please visit using a browser with javascript enabled.

If loading fails, click here to try again

Start

Congratulations - you have completed Antimicrobial and Antiviral Pharmacology- Part 1. You scored %%SCORE%% out of %%TOTAL%%. Your performance has been rated as %%RATING%%

Your answers are highlighted below.

Question 1

You are a physician and epidemiologist employed by the US Centers for Disease Control and You get an urgent phone call stating that an envelope was opened in the mail room of a large corporation, and s imilar ones were delivered to various government offices. Some sort of white powder fell out and was blown around the room, exposing dozens of workers. The suspicion i s anthrax. Which drug would be best, most properly indicated, for prophylaxis i f the substance tests positive for Bacillus anthracis?

A	Azithromycin
B	Clarithromycin
C	Doxycycline
D	Hydroxychloroquine
E	Metronidazole

Question 1 Explanation:

Sulfonamides cross the placenta and enter the fetus in concentrations sufficient to produce toxic effects. They compete with and displace bilirubin from plasma protein binding sites, raising free bilirubin levels and causing the jaundice and other manifestations of kernicterus. For the same reason, sulfonamides should also not be given to neonates, especially premature infants. This woman should not have been given the sulfonamide, whether alone or in combination with trimethoprim. Nitrofurantoin usually would be preferred for uncomplicated urinary tract infections in pregnant women. None of the other drugs are associated with this neonatal hyperbilirubinemia: amoxicillin or other aminopenicillins, a; azithromycin, b; erythromycin, c; or cephalosporins, fourth-generation or other, d

Question 2

A jaundiced 1-day-old premature infant with an elevated free bili-rubin i s seen in the premature baby The mother had received an antibiotic combination for a urinary tract infection (UTI) 1 week before delivery. Which antibiotic drug or class was the most l ikely cause of the baby’s kernicterus?

A	An aminopenicillin (eg, amoxicillin)
B	Azithromycin
C	Erythromycin
D	Fourth-generation cephalosporin
E	Sulfamethoxazole plus trimethoprim

Question 2 Explanation:

Resistance develops rapidly when only zidovudine or another nucleoside analog is used to treat HIV. It most likely involves decreased incorporation of the active metabolite into viral DNA, or increased excision of it from viral DNA. Zidovudine and other nucleoside analogs must be phosphorylated (not dephosphorylated, a) to form the active metabolite, the dideoxynucleotide triphosphate. It occurs via the actions of several kinases in host cells. That levels of active metabolite in CSF are undetectable (a) is false. In most cases CSF concentrations of active drug reach about 60% of those measured in the plasma at the same time. The ultimate effect of these drugs is, indeed, to stop viral nucleic acid synthesis (c), but that occurs only after the administered drug is phosphorylated (to form the nucleotide/triphosphate). The active metabolite is a good substrate for HIV reverse transcriptase, but a very poor one for DNA polymerases in host cells (and so e is incorrect). And the main adverse responses to or side effects associated with zidovudine? They include bone marrow toxicity, leukopenia/granulocytopenia, and anemia; potentially severe or persistent insomnia and headache, nausea, and vomiting. The side effects profiles differ somewhat among the other dideoxynucleosides.

Question 3

You are caring for a patient with HIV infection and will start drug therapy initially with the nucleoside analog zidovudine (formerly called azidothymidine, or AZT). Which statement most correctly describes zidovudine or the dideoxynucleoside class to which i t belongs?

A	Levels of active metabolite in cerebrospinal fluid usually are not detectable (ie, zero) because i t cannot cross the blood–brain barrier
B	Resistance to these antivirals develops rapidly after monotherapy starts, involves decreased incorporation of active metabolite into vi ral DNA
C	The dideoxynucleoside stops vi ral nucleic acid synthesis
D	The active metabolite i s an equally effective substrate for vi ral reverse transcriptase and mammalian DNA polymerase, which explains the high incidence of host toxicity
E	Zidovudine i s dephosphorylated to form the active metabolite, which i s incorporated into vi ral nucleic acid via HIV reverse transcriptase

Question 3 Explanation:

Although several of the antimicrobial agents listed here can cause one (or perhaps two) of the adverse responses noted here, nitrofurantoin is the most likely cause. GI side effects (anorexia, nausea, and vomiting) are the most common side effects caused by this drug, which is still widely used for managing acute lower urinary tract infections (eg, from many strains of E. coli, staphylococci, streptococci, Neisseria, Bacteroides). However, the drug can also cause acute or subacute pulmonary reactions such as those described, various hematologic reactions (in particular, leukopenia and thrombocytopenia), and peripheral sensory and motor neuropathies. Amoxicillin (a)—and most other penicillins—may cause central neurotoxicity if present at extraordinarily high plasma levels. Beyond that, allergic reactions are the most important adverse responses. Pulmonary, hematologic, and peripheral neuropathic adverse responses are not associated with these drugs. Azithromycin’s (b) profile of adverse effects is quite similar to that of erythromycin and other macrolides, and that profile does not include the signs and symptoms noted here (GI upset, mild to severe, are the most common complaints, and azithromycin may be ototoxic, a property not shared by other macrolides). Ciprofloxacin (c; or other fluoroquinolones) is not likely to cause any of the adverse responses noted. They are quite well tolerated and cause a variety of side effects that, in general, are mild. If one were to recall one “unique” toxicity, it would be alterations of collagen metabolism that may lead to tendon rupture. There is also evidence that the drug can prolong the QT interval, leading to arrhythmias, particularly in patients with long QT syndrome. Isoniazid (d) can cause peripheral neuropathy (mainly from a drug-induced pyridoxine deficiency) and hepatotoxicity. Pulmonary and bleeding problems are not at all common in terms of drug-induced problems.

Question 4

A patient on antimicrobial therapy develops the following s igns and symptoms that ultimately are found to be drug-induced: cough, dyspnea, and pulmonary infiltrates; neutropenia and bleeding tendencies; and What was the most l ikely cause of this patient’s symptoms?

A	Amoxicillin
B	Azithromycin
C	Ciprofloxacin
D	Isoniazid
E	Nitrofurantoin

Question 4 Explanation:

More so than any other antibiotic, clindamycin is associated with the highest risk of AAPMC (C. difficile superinfection). Thus, it is mainly reserved for certain anaerobic infections located outside the CNS (susceptible anaerobes include B. fragilis, Fusobacterium, and Clostridium perfringens, plus anaerobic streptococci). Tetracycline use is also associated with AAPMC. The phenomenon is not typically attributed to treatment with amoxicillin (a), azithromycin (b), or the trimethoprim-sulfamethoxazole combination (e). Metronidazole (d) or vancomycin (not listed) are considered preferred treatments for AAPMC—and the offending drug should be stopped as soon as AAPMC is suspected.

Question 5

A patient presents with severe, unrelenting diarrhea, and the fluid and electrolyte imbalances one would expect from She had been started on an antibiotic recently, and the l ikely diagnosis i s antibiotic-associated pseudomembranous colitis (AAPMC). What drug was the most l ikely cause?

A	Amoxicillin
B	Azithromycin
C	Cl indamycin
D	Metronidazole
E	Trimethoprim plus sulfamethoxazole (TMP-SMZ)

Question 5 Explanation:

Metronidazole is distributed to all body fluids and tissues. Its spectrum of activity is limited largely to anaerobic bacteria—including B. fragilis—and certain protozoa. It is considered to be the drug of choice for trichomoniasis in females and carrier states in males, as well as for intestinal infections with Giardia lamblia. Doxycycline (a), emetine (b, an antiprotozoal), pentamidine (d; used for treatment of P. jirovecii, pneumonia, or prophylactically for that condition in high-risk HIV-positive patients), and pyrazinamide (e, a bactericidal agent used for M. tuberculosis infections) would not be appropriate for the patient described in the question.

Question 6

A 35-year-old woman complains of i tching in the vulval Hanging-drop examination of the urine reveals tri chomonads. What i s the preferred treatment for the tri chomoniasis?

A	Doxycycline
B	Emetine
C	Metronidazole
D	Pentamidine
E	Pyrazinamide

Question 6 Explanation:

Hemolysis is the most common and serious adverse response to prima-quine. The risk is clearly highest in patients who have red cell deficiencies in glucose-6-phosphate dehydrogenase, a heritable trait and one that can be screened for before giving the drug. (This G6PD deficiency is more common in blacks, and whites with darker skin [eg, some from certain regions of the Middle East or the Mediterranean countries].) Regardless of the results of pretreatment screening, periodic blood counts should be done, and the urine checked for unusual darkening (indicating the presence of hemoglobin from lysed red cells), during treatment. Electrophysiologic changes, whether they affect the conducting tissues of the heart (a) or the brain (e) are not commonly associated with primaquine. The same applies to renal (c) or retinal (d) pathology, which occur at far lower rates than the hemolytic disease. Note: If you answered “retinopathy (d),” you were probably thinking about chloroquine, because that adverse response (accompanied by visual changes) is associated with that other commonly used antimalarial drug.

Question 7

A patient will be started on primaquine to treat active Plasmodium vivax malaria, specifically to target the hepatic forms of the Before you administer the drug you should screen the patient to assess their relative ri sk of developing a relatively common and severe adverse response to the drug. What i s that primaquine-associated ri sk?

A	Cardiac conduction disturbances
B	Hemolytic disease
C	Nephrotoxicity
D	Retinopathy
E	Seizures, convulsions

Question 7 Explanation:

Linezolid is a bacteriostatic (not cidal, so answer a is wrong) inhibitor of protein synthesis. Its unique mechanism of action, binding to the 23S portion of the 50S ribosomal subunit, ultimately blocks formation of the initiator complex that is necessary for bacterial replication. This unique mechanism means linezolid is not susceptible to cross-resistance that may have developed to other antibiotics, but the more the drug is used the greater the likelihood that resistance to it will develop. Linezolid is, indeed, the preferred drug for vancomycin-resistant enterococci. Vancomycin is often used as a “drug of last resort” for serious infections that cannot be treated with first-line alternatives. Another major use is for methicillin-resistant Staph. aureus, for which linezolid andvancomycin seem to be equally efficacious. (There are other approved uses for linezolid, but since few bacteria are resistant to it—so far—it should be used sparingly, only when absolutely needed.) It is not at all indicated for relatively minor infections, especially those with gramnegative causes (b). It is not a preferred alternative to amoxicillin for otitis media (c). Doxycycline, not linezolid, is the preferred alternative to ciprofloxacin for anthrax prophylaxis or treatment (d). The most serious adverse effect associated with linezolid is reversible myelosuppression. Complete blood counts need to be done at least once a week if this drug is being administered to myelosuppressed patients (including those taking other myelosuppressive drugs) or if linezolid therapy lasts more than about 14 days.

Question 8

On morning rounds in the hospital you encounter a patient being treated with l inezolid, the fi rst approved member of the oxazolidine class of Which statement accurately describes a characteristic of this drug?

A	Exerts strong bactericidal effects
B	Mainly used for relatively minor infections with gram-negative organisms
C	Preferred alternative to amoxicillin for children with otitis media
D	Preferred alternative to ciprofloxacin for B. anthracis infections
E	Suitable for vancomycin-resistant enterococci

Question 8 Explanation:

Rifampin induces cytochrome P450 enzymes, which causes a significant increase in elimination rates of many interacting drugs, such as oral contraceptives, anticoagulants, ketoconazole, cyclosporine, and chloramphenicol. It also promotes urinary excretion of methadone, which may precipitate withdrawal. Ethambutol (a), isoniazid (b), pyrazinamide (c), and vitamin B6 (e) are not P450 inducers, although the metabolism of some of these drugs can be induced by rifampin.

Question 9

A 59-year-old woman i s diagnosed with tuberculosis (TB). Before prescribing a multidrug regimen, you take a careful medication history because one of the drugs commonly used to treat TB induces some of the microsomal cytochrome P450 enzymes in the l iver, and i s a common cause of drug–drug What i s the most l ikely drug?

A	Ethambutol
B	Isoniazid
C	Pyrazinamide
D	Rifampin
E	Vitamin B6

Question 9 Explanation:

Protease inhibitors, as a class, tend to cause hyperglycemia (probably involves insulin resistance in parenchymal cells) and hyperlipidemia (precise mechanism not known). The other adverse responses listed are more typical of those caused by nucleoside reverse transcriptase inhibitors (NRTIs; zidovudine, others), and it is worthwhile commenting on that here. Anemias and neutropenia (myelosuppression, a) are fairly common with NRTIs. The risk of NRTIinduced lactic acidosis is rare, but the risks go up significantly if the patient receives more than one NRTI. Lactic acidosis tends to develop along with hepatomegaly and fatty liver degeneration (steatosis). Peripheral neuropathies (d) tend to be associated with didanosine and stavudine but not with other members of the NRTI class including the prototype, zidovudine. Pancreatitis (e) is also mainly associated with NRTIs (and among the class, mainly didanosine and stavudine), not with protease inhibitors.

Question 10

A patient with HIV infection i s receiving a combination of protease inhibitors as part of overall antiviral What i s , ordinarily, the most l ikely/most common s ide effect(s) of the protease inhibitors?

A	Anemia and neutropenia
B	Hyperglycemia and hyperlipidemia
C	Lactic acidosis
D	Neuropathy
E	Pancreatitis

Question 10 Explanation:

Primaquine is effective against the extraerythrocytic forms of P. vivax and P. ovale, and is also indicated for some cases of P. falciparum. It helps eradicate plasmodia from the liver, and in doing so it not only provides a cure but also helps prevent relapse. Chloroguanide (a) is a very old antimalarial drug but is seldom used instead of primaquine. Chloroquine (b) would not be used because it is effective only in the erythrocytic phase of the malarial parasites’ life span: it will not work against the exoerythrocytic forms of malaria parasites, nor can it serve as primary prevention. This 4-aminoquinoline derivative is a weak base that selectively concentrates in infected red blood cells. There it probably interferes with the ability of plasmodia to convert heme—a toxin to the parasite—to nontoxic metabolites. Pyrimethamine (d) and quinacrine (e) are not suitable agents for treating the patient described in the question

Question 11

A 27-year-old woman has just returned from a trip to Southeast Over the past 24 hours she has developed shaking, chills, and a temperature of 104°F. A blood smear reveals Plasmodium vivax. What drug would you prescribe to eradicate the extraerythrocytic phase of the organism?

A	Chloroguanide
B	Chloroquine
C	Primaquine
D	Pyrimethamine
E	Quinacrine

Question 11 Explanation:

Vancomycin, which must be given intravenously, has an antimicrobial spectrum closest to those of penicillins and cephalosporins, and it does not cross react in immunologically susceptible patients. Like penicillins and cephalosporins, there is a growing risk of resistance to vancomycin (particularly in hospital settings, where the drug is mainly used), but it nonetheless is considered the best (if not the last resort) drug for these patients. Clotrimazole (a) is an antifungal drug, mainly used for such fungal infections as those involving Candida. Metronidazole (c) is also used mainly for systemic or urinary tract fungal infections, although it does have some antibacterial activity. Gentamicin (b) would be inappropriate, in part because its spectrum of activity is not likely to include organisms killed or inhibited by penicillins, cephalosporins, or vancomycin. The same applies to tetracyclines (d)

Question 12

A patient has a severe bacterial infection that normally would respond to an oral penicillin or However, his chart documents anaphylactoid reactions to both classes of drugs. Given the history, what drug would be preferred for treating the infection, and also poses the least ri sk of cross-reactivity and an allergic response?

A	Clotrimazole
B	Gentamicin
C	Metronidazole
D	Tetracycline
E	Vancomycin

Question 12 Explanation:

One of zidovudine’s major adverse effects is bone marrow depression that appears to be dose- and length-of-treatment-dependent. The severity of the disease and a low CD4 count contribute to the bone marrow depression.

Question 13

A 40-year-old man i s HIV-positive and has a cluster-of-differentiation-4 (CD4) count of 200/mm3. Within 2 months after starting drug therapy for his HIV he develops a peripheral white blood cell count of 1000/mm3 and a hemoglobin of 0 mg/dL. Which drug most l ikely caused the hematologic abnormalities?

A	Acyclovir
B	Dideoxycytidine
C	Foscarnet
D	Rimantadine
E	Zidovudine

Question 13 Explanation:

Unlike the other listed drugs, oxacillin is resistant to penicillinase (β-lactamase) and it is one of a relatively few penicillins classified as anti-staphylococcal agents. (The main other ones are cloxacillin, dicloxacillin, and nafcillin.) Oxacillin and the related drugs are generally specific for gram-positive microorganisms. The other drugs listed are broad- (or extended-) spectrum penicillins. Penicillin G (the intravenous dosage form) or V (oral) is indicated for staph infections provided the strains do have β- lactamase activity.

Question 14

An 86-year-old man complains of cough and blood in his sputum for the past 5 On admission, his temperature i s 103°F. Physical examination reveals rales in his right lung, and x-ray examination shows increased density in the right middle lobe. A sputum smear shows many grampositive cocci, confirmed by sputum culture as penicillinase-producing Staphylococcus aureus. Which antibiotic would be best to administer fi rst?

A	Ampicillin
B	Mezlocillin
C	Oxacillin
D	Penicillin (G or V)
E	Ticarcillin

Question 14 Explanation:

Of all the protein synthesis inhibitors, only the aminoglycosides routinely cause bacterial death (bactericidal effect), not just suppression of growth or replication (bacteriostatic effect). Clindamycin (b) and erythromycin (c) have bacteriostatic effects, the main mechanism being binding to the 50S subunit of bacterial ribosomes. Linezolid (d) is also mainly a bacteriostatic drug (against staphylococci, and enterococci, for example), although in some cases it can exert bactericidal effects on some strains of streptococci. Tetracyclines (e) are largely bacteriostatic and have a broad spectrum of activity. They bind reversibly to the ribosomal 30S subunit. The ultimate effect is inhibition of amino acid incorporation into peptides that otherwise would be formed via RNA activity.

Question 15

When considering all the main antibacterial drugs that work by inhibiting protein synthesis in one way or another, vi rtually every one exerts bacteriostatic Which drug or drug class differs from the rest because the usual consequence of therapeutic plasma levels i s bactericidal, rather than mere inhibition of bacterial growth and replication?

A	Aminoglycosides
B	Cl indamycin
C	Erythromycins
D	Linezolid
E	Tetracyclines

Question 15 Explanation:

Zidovudine competitively inhibits HIV-1 nucleoside reverse transcriptase. Zidovudine is a prodrug: it must be metabolically activated (phosphorylated) to zidovudine triphosphate. The active metabolite is incorporated in the growing viral DNA chain, and in doing so prevents reverse transcriptase from adding more bases. As a result, DNA strand growth stops. Zidovudine decreases the rate of clinical disease progression and prolongs survival in HIV-infected patients when used as part of a multidrug treatment plan. An example of a nonnucleoside reverse transcriptase inhibitor (a) is efavirenz. Unlike zidovudine, it is not a structural analog of naturally occurring nucleosides, and does not work by causing premature termination of DNA growth. It and other nonnucleoside reverse transcriptase inhibitors work mainly by directly binding to, and inhibiting, reverse transcriptase. Protease inhibitors (e) block the final step in HIV maturation. Recall that HIV proteins are synthesized together as one long peptide that is largely without biological activity. Protease cleaves the polyprotein into several separate—and functional—proteins. Without this final processing step HIV cannot form new, and infectious, virus particles. Typically, protease inhibitor therapy involves two drugs, lopinavir plus ritonavir being the most common.

Question 16

A patient with HIV infection and cl inical AIDS i s treated with a combination of agents, one of which i s Which enzyme or replicative process i s the main target of this antiviral drug?

A	Nonnucleoside reverse transcriptase
B	Nucleoside reverse transcriptase
C	RNA synthesis
D	Viral particle assembly
E	Viral proteases

Question 16 Explanation:

Bacterial DNA gyrase is composed of four subunits. Ciprofloxacin, levofloxacin, and other quinolones bind to the strand-cutting subunits and in doing so inhibits bacterial growth and replication. (The original member of this group was nalidixic acid.) These antibiotics have a broad spectrum of antibiotic activity and are relatively free from common or serious side effects (some members associated with significant toxicities were withdrawn from the market), and tend not to be associated with rapidly developingantibiotic tolerance to their actions.

Question 17

A patient with HIV/AIDS, being treated with multiple antiviral and immunosuppressive drugs, develops an opportunistic infection caused by jiroveci. Which drug are you most l ikely to use to treat the pulmonary infection caused by this protozoan?

A	Carbenicillin
B	Metronidazole
C	Nifurtimox
D	Penicillin G.
E	Pentamidine

Question 17 Explanation:

Pentamidine is effective in pneumonia caused by P. jiroveci. (So is the trimethoprim-sulfamethoxazole combination, not listed.) This protozoal disease usually occurs in immunodeficient patients, such as those with AIDS. Nifurtimox (c) is effective in trypanosomiasis, and metronidazole (b) in amebiasis and leishmaniasis, as well as in anaerobic bacterial infections. Penicillins (a or d) are not considered drugs of choice for protozoal diseases such as those mentioned here.

Question 18

A 25-year-old woman with an upper respiratory tract infection caused by influenzae i s treated with trimethoprim-sulfamethoxazole. She responds well in a matter of days after starting the TMP-SMZ. Which bacterial process i s inhibited by this combination, and accounts for the antibacterial effects?

A	Cell-wall synthesis
B	Protein synthesis
C	Folic acid synthesis
D	Topoisomerase II (DNA gyrase)
E	DNA polymerase

Question 18 Explanation:

Trimethoprim inhibits dihydrofolic acid reductase. Sulfamethoxazole inhibits p-aminobenzoic acid (PABA) from being incorporated into folic acid by competitive inhibition of dihydropteroate synthase. Either action inhibits the synthesis of tetrahydrofolic acid, but by giving the combination we inhibit two essential and sequential steps in the formation of folate-dependent metabolites that are necessary for bacterial viability and replication.

Question 19

A man who has been at the local tavern, drinking alcohol heavily, i s He i s transported to the hospital. Among various findings i s an infection for which prompt antibiotic therapy i s indicated. Given his high blood alcohol level, which antibiotic should be avoided because of a high potential of causing a serious disulfiram-like reaction that might provoke ventilatory or cardiovascular failure? (Assume that were i t not for the alcohol consumption, the antibiotic would be suitable for the infectious organisms that have been detected.)

A	Amoxicillin
B	Cefotetan
C	Erythromycin ethylsuccinate
D	Linezolid
E	Penicillin G

Question 19 Explanation:

Cefotetan (second-generation cephalosporin)—as well as cefoperazone (third-generation) inhibit aldehyde dehydrogenase and cause accumulation of acetaldehyde (as does disulfiram, which is used to curb alcohol intake), and so can cause all the typical and potentially serious consequences of a disulfiram-like reaction. Cefmetazole, a secondgeneration cephalosporin, and metronidazole, also cause a similar adverse interaction with alcohol. (Note that these three cephalosporins are also the ones that are associated with vitamin K-related bleeding problems, as addressed in Question 434.) Erythromycin (whether administered as the base or one of the common salts, eg, ethylsuccinate, estolate, or stearate) can inhibit the hepatic P450 system sufficient to cause adverse interactions with (excessive effects of) such drugs as warfarin, carbamazepine, and theophylline. However, based on current evidence there is no specific inhibition of aldehyde dehydrogenase, nor resulting accumulation of acetaldehyde, that would correctly qualify as a disulfiram-like interaction. Amoxicillin, penicillin G, and other penicillins do not participate in disulfiram-like reactions. Linezolid inhibits monoamine oxidase (MAO), albeit weakly, and so can trigger potentially significant adverse interactions in persons receiving such sympathomimetics as cocaine, ephedrine, or pseudoephedrine; or those consuming tyramine-rich foods or beverages. However, the drug does not inhibit alcohol metabolism or cause the adverse responses noted in this question.

Question 20

A 43-year-old woman i s recovering from major surgery, following discharge from the hospital, in an assisted-care She develops fever, rales, dyspnea, cough, and purulent sputum. Results of a chest radiograph indicate bilateral pulmonary infiltrates. We send blood and sputum cultures to the cl inical pathology lab for culturing, but now must turn our attention to what we believe i s community-acquired pneumonia caused by antibiotic-resistant pneumococci. We want to start empiric antibiotic therapy until culture results are available. Which drug would be best for this initial therapy?

A	Amoxicillin
B	Cefazolin
C	Erythromycin
D	Levofloxacin
E	Penicillin G
F	Vancomycin

Question 20 Explanation:

Levofloxacin or another quinolone blocks bacterial DNA synthesis by inhibiting bacterial DNA gyrase (topoisomerase II). Either would be a good choice, not only because of their antibiotic spectrum of activity, but also because the working hypothesis is that we’re dealing with a community-acquired respiratory infection caused by resistant bacteria. The resistance is likely to render penicillins (a, e), cephalosporins (b), and even erythromycin or other macrolides (c) ineffective. Resistance to fluoroquinolones has not become that much of a problem yet. Note that cefazolin (b), a first-generation cephalosporin, is ineffective against pneumococci, and is mainly suitable only for infections with S. aureus or streptococci that are not resistant to penicillins. Vancomycin (f) might ultimately be needed, but since it must be given parenterally (there was no mention that the patient was unable to take oral medications) it would be premature to use this otherwise “last resort” antibiotic.

Question 21

Blood and sputum cultures taken in a cri ti cally i l l 26-year-old woman indicate the presence of MRSA—methicillin-resistant aureus. Which drug i s most l ikely to be effective in treating this infection?

A	Amoxicillin plus clavulanic acid
B	Cl indamycin
C	Erythromycin
D	Trimethoprim-sulfamethoxazole (TMP-SMZ)
E	Vancomycin

Question 21 Explanation:

The only suitable drug listed for this potentially fatal infection is vancomycin. The finding of MRSA is not uncommon, particularly in hospitals, rendering therapy with penicillins (including amoxicillin with clavulanate, the β-lactamase inhibitor; a) ineffective. Macrolides (including clindamycin, b; and erythromycin, c) are also unsuitable, in part because of a growing resistance problem. Resistance to the trimethoprim-sulfa-methoxazole (d) combination is also a major problem, regardless of the infections for which this folate reductase inhibitor therapy is prescribed.

Question 22

Compared with most other cephalosporins, the administration of cefmetazole, cefoperazone, or cefotetan i s associated with a higher incidence of an adverse response that i s particularly dangerous for some What i s that rather unique adverse response?

A	Acute heart failure
B	Acute renal failure
C	Bleeding tendencies in patients taking warfarin
D	Hypertension
E	Ototoxicity

Question 22 Explanation:

Cefmetazole and cefotetan, both second-generation cephalosporins, and cefoperazone (third generation) can interfere with hepatic vitamin K metabolism, causing hypoprothrombinemia and what amounts to a deficiency of vitamin K-dependent clotting factor activity. Because this is the general mechanism by which warfarin exerts its anticoagulant effects, combined use of one of these cephalosporins can cause further (and potentially dangerous) prolongations of the International Normalized Ratio (or prothrombin time); the clinical consequence can be spontaneous, prolonged, or excessive bleeding. One should also be cautious when these cephalosporins are given to patients taking aspirin or other antiplatelet drugs (eg, clopidogrel) or thrombolytics. Although most cephalosporins are excreted unchanged by the kidneys, renal failure (b, especially severe and acute) seldom occurs with these or other cephalosporins. There is no link between administration of even high doses of these cephalosporins (or others) with the development of acute heart failure (a). Hypertension (d) or other substantial changes of blood pressure are not associated with cephalosporins, nor are these drugs ototoxic (e). Although a history of severe allergic reactions to penicillins requires caution when considering a cephalosporin (indeed, cephalosporins should be avoided, if possible, in such patients), there is nothing unique about cefmetazole, cefoperazone, or cefotetan in this context. None of the cephalosporins are contraindicated for patients with mild allergic reactions due to penicillins.

Question 23

A patient develops muscle aches and pains during the course of antibiotic A muscle biopsy would clearly show myopathy. Which drug most l ikely (and rather uniquely) caused this adverse effect on skeletal muscle?

A	Daptomycin
B	Erythromycin
C	Gentamicin
D	Linezolid
E	Vancomycin

Question 23 Explanation:

Daptomycin, classified as a cyclic lipopeptide and rapidly bactericidal against nearly all gram-positive bacteria, is uniquely associated (among antimicrobial agents) with myopathy and its typical signs and symptoms. Daily dosages currently recommended pose a low risk of myositis and myopathy, but nevertheless creatine kinase levels (marker of muscle damage) should be measured periodically during the course of therapy and the patient should be advised to report any relevant symptoms at once. None of the other drugs listed are associated with myopathy. GI side effects are quite common with usual doses of erythromycin (b) and other macrolides, and sudden cardiac death (from QT prolongation) has been reported when erythromycin blood levels get too high. The estolate salt of erythromycin estolate (salt) may cause cholestatic hepatitis. Gentamicin (c, and most other aminoglycosides) generally cause few minor side effects; their major adverse effects are ototoxicity and nephrotoxicity. The main common side effects associated with linezolid (d) are nausea and diarrhea, and the potential for usually reversible myelosuppression and pancytopenia. Vancomycin (e) tends to cause facial and neck flushing, pruritus, and urticaria (so-called “red man syndrome”), probably secondary to local histamine release; histamine release may also contribute to the development of tachycardia and hypotension. As with the aminoglycosides, vancomycin is ototoxic at high plasma levels.Daptomycin, classified as a cyclic lipopeptide and rapidly bactericidal against nearly all gram-positive bacteria, is uniquely associated (among antimicrobial agents) with myopathy and its typical signs and symptoms. Daily dosages currently recommended pose a low risk of myositis and myopathy, but nevertheless creatine kinase levels (marker of muscle damage) should be measured periodically during the course of therapy and the patient should be advised to report any relevant symptoms at once. None of the other drugs listed are associated with myopathy. GI side effects are quite common with usual doses of erythromycin (b) and other macrolides, and sudden cardiac death (from QT prolongation) has been reported when erythromycin blood levels get too high. The estolate salt of erythromycin estolate (salt) may cause cholestatic hepatitis. Gentamicin (c, and most other aminoglycosides) generally cause few minor side effects; their major adverse effects are ototoxicity and nephrotoxicity. The main common side effects associated with linezolid (d) are nausea and diarrhea, and the potential for usually reversible myelosuppression and pancytopenia. Vancomycin (e) tends to cause facial and neck flushing, pruritus, and urticaria (so-called “red man syndrome”), probably secondary to local histamine release; histamine release may also contribute to the development of tachycardia and hypotension. As with the aminoglycosides, vancomycin is ototoxic at high plasma levels.Daptomycin, classified as a cyclic lipopeptide and rapidly bactericidal against nearly all gram-positive bacteria, is uniquely associated (among antimicrobial agents) with myopathy and its typical signs and symptoms. Daily dosages currently recommended pose a low risk of myositis and myopathy, but nevertheless creatine kinase levels (marker of muscle damage) should be measured periodically during the course of therapy and the patient should be advised to report any relevant symptoms at once. None of the other drugs listed are associated with myopathy. GI side effects are quite common with usual doses of erythromycin (b) and other macrolides, and sudden cardiac death (from QT prolongation) has been reported when erythromycin blood levels get too high. The estolate salt of erythromycin estolate (salt) may cause cholestatic hepatitis. Gentamicin (c, and most other aminoglycosides) generally cause few minor side effects; their major adverse effects are ototoxicity and nephrotoxicity. The main common side effects associated with linezolid (d) are nausea and diarrhea, and the potential for usually reversible myelosuppression and pancytopenia. Vancomycin (e) tends to cause facial and neck flushing, pruritus, and urticaria (so-called “red man syndrome”), probably secondary to local histamine release; histamine release may also contribute to the development of tachycardia and hypotension. As with the aminoglycosides, vancomycin is ototoxic at high plasma levels.Daptomycin, classified as a cyclic lipopeptide and rapidly bactericidal against nearly all gram-positive bacteria, is uniquely associated (among antimicrobial agents) with myopathy and its typical signs and symptoms. Daily dosages currently recommended pose a low risk of myositis and myopathy, but nevertheless creatine kinase levels (marker of muscle damage) should be measured periodically during the course of therapy and the patient should be advised to report any relevant symptoms at once. None of the other drugs listed are associated with myopathy. GI side effects are quite common with usual doses of erythromycin (b) and other macrolides, and sudden cardiac death (from QT prolongation) has been reported when erythromycin blood levels get too high. The estolate salt of erythromycin estolate (salt) may cause cholestatic hepatitis. Gentamicin (c, and most other aminoglycosides) generally cause few minor side effects; their major adverse effects are ototoxicity and nephrotoxicity. The main common side effects associated with linezolid (d) are nausea and diarrhea, and the potential for usually reversible myelosuppression and pancytopenia. Vancomycin (e) tends to cause facial and neck flushing, pruritus, and urticaria (so-called “red man syndrome”), probably secondary to local histamine release; histamine release may also contribute to the development of tachycardia and hypotension. As with the aminoglycosides, vancomycin is ototoxic at high plasma levels.Daptomycin, classified as a cyclic lipopeptide and rapidly bactericidal against nearly all gram-positive bacteria, is uniquely associated (among antimicrobial agents) with myopathy and its typical signs and symptoms. Daily dosages currently recommended pose a low risk of myositis and myopathy, but nevertheless creatine kinase levels (marker of muscle damage) should be measured periodically during the course of therapy and the patient should be advised to report any relevant symptoms at once. None of the other drugs listed are associated with myopathy. GI side effects are quite common with usual doses of erythromycin (b) and other macrolides, and sudden cardiac death (from QT prolongation) has been reported when erythromycin blood levels get too high. The estolate salt of erythromycin estolate (salt) may cause cholestatic hepatitis. Gentamicin (c, and most other aminoglycosides) generally cause few minor side effects; their major adverse effects are ototoxicity and nephrotoxicity. The main common side effects associated with linezolid (d) are nausea and diarrhea, and the potential for usually reversible myelosuppression and pancytopenia. Vancomycin (e) tends to cause facial and neck flushing, pruritus, and urticaria (so-called “red man syndrome”), probably secondary to local histamine release; histamine release may also contribute to the development of tachycardia and hypotension. As with the aminoglycosides, vancomycin is ototoxic at high plasma levels.

Question 24

A patient with an infectious disease routinely takes their antimicrobial medication with milk or other dairy products in an attempt to reduce stomach upset from the The antibiotic fails to work adequately because calcium in the dairy products chelates the drug and reduces i ts oral bioavailability. Which antimicrobial drug or drug class was the patient most l ikely taking?

A	Aminoglycoside
B	Antimycobacterial drug, specifically i soniazid
C	Cephalosporin, fi rst generation
D	Cephalosporin, third generation
E	Penicillin
F	Tetracycline

Question 24 Explanation:

Tetracyclines interact with many polyvalent metal cations such that antibiotic absorption from the gut (ie, bioavailability) is reduced. The extent of this reduction can be clinically significant, that is, leading to inadequate blood levels and effects of the antibiotic. Calcium is, of course, abundant in dairy products, some OTC antacid products, and in supplements touted for “bone health.” Other metals that can interact with tetracyclines by this mechanism include iron, magnesium, aluminum, and zinc. Note that one or several of these interactants aretypically found in antacid products, multivitamin/mineral supplements, and even (the trend is growing) in some (mineral-) fortified foods, such as cereals, and citrus juices. Although foods (in general) may interfere with the oral absorption of several other antibiotics, the cation-antibiotic interaction is specific for and important to the tetracyclines.

Once you are finished, click the button below. Any items you have not completed will be marked incorrect. Get Results

There are 24 questions to complete.

←

List

→

Return

Shaded items are complete.

1	2	3	4	5
6	7	8	9	10
11	12	13	14	15
16	17	18	19	20
21	22	23	24	End

Return

See all quizzes of the Antimicrobial and Antiviral Pharmacology at here:

Part 1 | Part 2

II. Preview all questions below

1.You are a physician and epidemiologist employed by the US Centers for Disease Control and You get an urgent phone call stating that an envelope was opened in the mail room of a large corporation, and s imilar ones were delivered to various government offices. Some sort of white powder fell out and was blown around the room, exposing dozens of workers. The suspicion i s anthrax. Which drug would be best, most properly indicated, for prophylaxis i f the substance tests positive for Bacillus anthracis?

Azithromycin
Clarithromycin
Doxycycline
Hydroxychloroquine
Metronidazole

2. A jaundiced 1-day-old premature infant with an elevated free bili-rubin i s seen in the premature baby The mother had received an antibiotic combination for a urinary tract infection (UTI) 1 week before delivery. Which antibiotic drug or class was the most l ikely cause of the baby’s kernicterus?

An aminopenicillin (eg, amoxicillin)
Azithromycin
Erythromycin
Fourth-generation cephalosporin
Sulfamethoxazole plus trimethoprim

3. You are caring for a patient with HIV infection and will start drug therapy initially with the nucleoside analog zidovudine (formerly called azidothymidine, or AZT). Which statement most correctly describes zidovudine or the dideoxynucleoside class to which i t belongs?

Levels of active metabolite in cerebrospinal fluid usually are not detectable (ie, zero) because i t cannot cross the blood–brain barrier
Resistance to these antivirals develops rapidly after monotherapy starts, involves decreased incorporation of active metabolite into vi ral DNA
The dideoxynucleoside stops vi ral nucleic acid synthesis
The active metabolite i s an equally effective substrate for vi ral reverse transcriptase and mammalian DNA polymerase, which explains the high incidence of host toxicity
Zidovudine i s dephosphorylated to form the active metabolite, which i s incorporated into vi ral nucleic acid via HIV reverse transcriptase

4. A patient on antimicrobial therapy develops the following s igns and symptoms that ultimately are found to be drug-induced: cough, dyspnea, and pulmonary infiltrates; neutropenia and bleeding tendencies; and What was the most l ikely cause of this patient’s symptoms?

Amoxicillin
Azithromycin
Ciprofloxacin
Isoniazid
Nitrofurantoin

5. A patient presents with severe, unrelenting diarrhea, and the fluid and electrolyte imbalances one would expect from She had been started on an antibiotic recently, and the l ikely diagnosis i s antibiotic-associated pseudomembranous colitis (AAPMC). What drug was the most l ikely cause?

Amoxicillin
Azithromycin
Cl indamycin
Metronidazole
Trimethoprim plus sulfamethoxazole (TMP-SMZ)

6. A 35-year-old woman complains of itching in the vulval Hanging-drop examination of the urine reveals trichomonads. What i s the preferred treatment for the trichomoniasis?

Doxycycline
Emetine
Metronidazole
Pentamidine
Pyrazinamide

7. A patient will be started on primaquine to treat active Plasmodium vivax malaria, specifically to target the hepatic forms of the Before you administer the drug you should screen the patient to assess their relative ri sk of developing a relatively common and severe adverse response to the drug. What i s that primaquine-associated ri sk?

Cardiac conduction disturbances
Hemolytic disease
Nephrotoxicity
Retinopathy
Seizures, convulsions

8. On morning rounds in the hospital you encounter a patient being treated with l inezolid, the first approved member of the oxazolidine class of Which statement accurately describes a characteristic of this drug?

Exerts strong bactericidal effects
Mainly used for relatively minor infections with gram-negative organisms
Preferred alternative to amoxicillin for children with otitis media
Preferred alternative to ciprofloxacin for B. anthracis infections
Suitable for vancomycin-resistant enterococci

9. A 59-year-old woman i s diagnosed with tuberculosis (TB). Before prescribing a multidrug regimen, you take a careful medication history because one of the drugs commonly used to treat TB induces some of the microsomal cytochrome P450 enzymes in the l iver, and i s a common cause of drug–drug What i s the most likely drug?

Ethambutol
Isoniazid
Pyrazinamide
Rifampin
Vitamin B₆

10. A patient with HIV infection i s receiving a combination of protease inhibitors as part of overall antiviral What i s , ordinarily, the most l ikely/most common s ide effect(s) of the protease inhibitors?

Anemia and neutropenia
Hyperglycemia and hyperlipidemia
Lactic acidosis
Neuropathy
Pancreatitis

11. A 27-year-old woman has just returned from a trip to Southeast Over the past 24 hours she has developed shaking, chills, and a temperature of 104°F. A blood smear reveals Plasmodium vivax. What drug would you prescribe to eradicate the extraerythrocytic phase of the organism?

Chloroguanide
Chloroquine
Primaquine
Pyrimethamine
Quinacrine

12. A patient has a severe bacterial infection that normally would respond to an oral penicillin or However, his chart documents anaphylactoid reactions to both classes of drugs. Given the history, what drug would be preferred for treating the infection, and also poses the least ri sk of cross-reactivity and an allergic response?

Clotrimazole
Gentamicin
Metronidazole
Tetracycline
Vancomycin

13. A 40-year-old man i s HIV-positive and has a cluster-of-differentiation-4 (CD4) count of 200/mm3. Within 2 months after starting drug therapy for his HIV he develops a peripheral white blood cell count of 1000/mm3 and a hemoglobin of 0 mg/dL. Which drug most l ikely caused the hematologic abnormalities?

Acyclovir
Dideoxycytidine
Foscarnet
Rimantadine
Zidovudine

14. An 86-year-old man complains of cough and blood in his sputum for the past 5 On admission, his temperature i s 103°F. Physical examination reveals rales in his right lung, and x-ray examination shows increased density in the right middle lobe. A sputum smear shows many grampositive cocci, confirmed by sputum culture as penicillinase-producing Staphylococcus aureus. Which antibiotic would be best to administer fi rst?

Ampicillin
Mezlocillin
Oxacillin
Penicillin (G or V)
Ticarcillin

15. When considering all the main antibacterial drugs that work by inhibiting protein synthesis in one way or another, vi rtually every one exerts bacteriostatic Which drug or drug class differs from the rest because the usual consequence of therapeutic plasma levels i s bactericidal, rather than mere inhibition of bacterial growth and replication?

Aminoglycosides
Cl indamycin
Erythromycins
Linezolid
Tetracyclines

16..A patient with HIV infection and cl inical AIDS i s treated with a combination of agents, one of which i s Which enzyme or replicative process i s the main target of this antiviral drug?

Nonnucleoside reverse transcriptase
Nucleoside reverse transcriptase
RNA synthesis
Viral particle assembly
Viral proteases

17. A patient with HIV/AIDS, being treated with multiple antiviral and immunosuppressive drugs, develops an opportunistic infection caused by jiroveci. Which drug are you most l ikely to use to treat the pulmonary infection caused by this protozoan?

Carbenicillin
Metronidazole
Nifurtimox
Penicillin G.
Pentamidine

18. A 25-year-old woman with an upper respiratory tract infection caused by influenzae i s treated with trimethoprim-sulfamethoxazole. She responds well in a matter of days after starting the TMP-SMZ. Which bacterial process i s inhibited by this combination, and accounts for the antibacterial effects?

Cell-wall synthesis
Protein synthesis
Folic acid synthesis
Topoisomerase II (DNA gyrase)
DNA polymerase

19. A man who has been at the local tavern, drinking alcohol heavily, i s He i s transported to the hospital. Among various findings i s an infection for which prompt antibiotic therapy i s indicated. Given his high blood alcohol level, which antibiotic should be avoided because of a high potential of causing a serious disulfiram-like reaction that might provoke ventilatory or cardiovascular failure? (Assume that were i t not for the alcohol consumption, the antibiotic would be suitable for the infectious organisms that have been detected.)

Amoxicillin
Cefotetan
Erythromycin ethylsuccinate
Linezolid
Penicillin G

20. A 43-year-old woman i s recovering from major surgery, following discharge from the hospital, in an assisted-care She develops fever, rales, dyspnea, cough, and purulent sputum. Results of a chest radiograph indicate bilateral pulmonary infiltrates. We send blood and sputum cultures to the cl inical pathology lab for culturing, but now must turn our attention to what we believe i s community-acquired pneumonia caused by antibiotic-resistant pneumococci. We want to start empiric antibiotic therapy until culture results are available. Which drug would be best for this initial therapy?

Amoxicillin
Cefazolin
Erythromycin
Levofloxacin Penicillin G
. Vancomycin

21. Blood and sputum cultures taken in a cri ti cally i l l 26-year-old woman indicate the presence of MRSA—methicillin-resistant aureus. Which drug i s most l ikely to be effective in treating this infection?

Amoxicillin plus clavulanic acid
Cl indamycin
Erythromycin
Trimethoprim-sulfamethoxazole (TMP-SMZ)
Vancomycin

22. Compared with most other cephalosporins, the administration of cefmetazole, cefoperazone, or cefotetan i s associated with a higher incidence of an adverse response that i s particularly dangerous for some What i s that rather unique adverse response?

Acute heart failure
Acute renal failure
Bleeding tendencies in patients taking warfarin
Hypertension
Ototoxicity

23. A patient develops muscle aches and pains during the course of antibiotic A muscle biopsy would clearly show myopathy. Which drug most l ikely (and rather uniquely) caused this adverse effect on skeletal muscle?

Daptomycin
Erythromycin
Gentamicin
Linezolid
Vancomycin

24. A patient with an infectious disease routinely takes their antimicrobial medication with milk or other dairy products in an attempt to reduce stomach upset from the The antibiotic fails to work adequately because calcium in the dairy products chelates the drug and reduces i ts oral bioavailability. Which antimicrobial drug or drug class was the patient most l ikely taking?

Aminoglycoside
Antimycobacterial drug, specifically i soniazid
Cephalosporin, fi rst generation
Cephalosporin, third generation Penicillin
Tetracycline

The quizzes about Antimicrobial and Antiviral Pharmacology – Part 1

I. Start the exam by click the “Start” button

Antimicrobial and Antiviral Pharmacology- Part 1

II. Preview all questions below

Share this:

Related

The quizzes about Endocrine and Reproductive Pharmacology – Part 2

The quizzes about Antimicrobial and Antiviral Pharmacology – Part 2

You may also like

Leave a Comment Cancel Reply