AL-Antiparasitic and antitubercular drugs-KEY.pdf

AL-Antiparasitic and antitubercular drugs - Confidential Course Name: # of Questions: 33 Date and Time of Exam Creation: Wed, Feb 21, 2024 @ 22:29:40 Exam Creator: [email protected] Current Date and Time: Wed, Feb 21, 2024 @ 22:31:57 Total Exam Points: 33.00 Scoring Method: DEFAULT Security Options: Sec...

AL-Antiparasitic and antitubercular drugs - Confidential Course Name: # of Questions: 33 Date and Time of Exam Creation: Wed, Feb 21, 2024 @ 22:29:40 Exam Creator: [email protected] Current Date and Time: Wed, Feb 21, 2024 @ 22:31:57 Total Exam Points: 33.00 Scoring Method: DEFAULT Security Options: Secure Exam Randomize Sequence Randomize All Choices Enabled Options: Numbering ____________________________________________________________________________ Question #: 1 1. Resistance to antimycobacterial agents in general 1 2. Ethambutol resistance most often results from 2 3. Resistance to isoniazid usually results from 3 4. Resistance to pyrazinamide is generally due to 4 A. mutations in the arabinosyl transferase gene, some of which cause overexpression of the target enzyme B. an inactivating mutation in the mycobacterial enzyme catalase-peroxidase, which converts isoniazid into its antimycobacterial form C. results from chromosomal mutations D. mutations in the pyrazinamidase gene, which result in the inability to convert the prodrug into its active form 1. C|C.| 2. A|A.| 3. B|B.| 4. D|D.| Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 2 ____________________ are semisynthetic derivatives that have replaced artemisinins, which are particularly well suited for the treatment of severe P. falciparum malaria and now play a key role in the combination therapy of drug-resistant infections. A. Chloroquine, hydroxychloroquine, primaquine ✓B. Dihydroartemisinin, artemether, artesunate C. Halofantrine, lumefantrine, mefloquine D. Atovaquone, proguanil, pyrimethamine Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 3 Arrange the following events of the mechanism of action of chloroquine (alphabetical) with respect to their sequential occurence (numerical). A. Accumulation of unpolymerized heme metabolite leads to active oxidative membrane damage and is toxic to the parasite 1 B. Chloroquine thus poisons the parasite by preventing the detoxification of a toxic product of hemoglobin catabolism 2 C. As a result, protonated chloroquine accumulates to high concentrations inside the parasite’s food vacuole, where it binds to ferriprotoporphyrin IX and inhibits the polymerization of the heme metabolite 3 D. Once inside the acidic environment of the parasite’s food vacuole, chloroquine is rapidly protonated, making it to unable to diffuse out of the vacuole 4 E. Chloroquine is a weak base that, in its neutral form, freely diffuses across the membrane of the parasite’s food vacuole 5 1. 2. 3. 4. 5. 1. 4|4.| 2. 5|5.| 3. 3|3.| 4. 2|2.| 5. 1|1.| Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 4 Chloroquine is highly effective against which of the following erythrocytic forms of plasmodial species/strains? A. P. vivax, P. ovale, P. malariae, and chloroquine-resistant strains of P. falciparum ✓B. P. vivax, P. ovale, P. malariae, and chloroquine-sensitive strains of P. falciparum C. P. vivax, and P. ovale only D. P. ovale, and P. malariae only Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 5 Chloroquine-resistant plasmodia accumulate less chloroquine inside food vacuoles than chloroquine-sensitive plasmodia do. Which of the following statements are correct? SATA ✓A. It is now ineffective against most strains of P. falciparum in Africa, Asia, and South America ✓B. Several mutations in PfCRT probably pumps protonated chloroquine out of the food vacuole ✓C. It is speculated that a second mutation provides a “corrective” action that allows chloroquine-resistant P. falciparum to continue growth in the presence of a pfcrt mutation D. Once inside the acidic environment of the parasite’s food vacuole, chloroquine is rapidly protonated, making it very easy to diffuse out of the vacuole Rationale: Once inside the acidic environment of the parasite’s food vacuole, chloroquine is rapidly protonated, making it very difficult to diffuse out of the vacuole Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 6 Each tuberculous lesion in an infected lung can contain 108 bacteria. The frequency of mutants resistant to any single antimycobacterial drug is about 1 in 106 bacteria. What would be the frequency of mutants resistant to the coadministration of four antimycobacterial drugs? A. 1012 B. 1016 C. 1018 ✓D. 1024 Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 7 FITB: ________________itself does not accumulate appreciably in tissues during long-term administration, except in erythrocytes, where its concentration is about three times that in plasma. A. Chloroquine ✓B. Proguanil C. Quinine D. Primaquine Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 8 FITB: Because of the protection conferred by their walls, the____________ of E histolytica or G lamblia can survive days to weeks in the external environment and are responsible for transmission. A. trophozoites B. flagellates ✓C. cysts D. eggs Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 9 FITB: Resistant mutants are present in all microbial populations at approximately 1 in 106 and are rapidly selected out if _____________ is used as a single drug, especially in a patient with active infection A. pyrazinamide ✓B. rifampin C. isoniazid D. ethambutol Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 10 FITB: The nitro group of ______________ is reduced by ferredoxin and the resulting products are responsible for disrupting the DNA helical structure which leads to inhibition of nucleic acid synthesis and causing strand breakage; ___________is amebicidal, bactericidal, trichomonacidal. A. Proguanil B. Isoniazid ✓C. Metronidazole D. Chloroquine Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 11 Hypnozoites are formed in the life cycle of which of the following plasmodial species? A. Plasmodium ✓B. Plasmodium C. Plasmodium D. Plasmodium falciparum, Plasmodium ovale vivax, Plasmodium ovale vivax, Plasmodium malariae falciparum, Plasmodium malariae Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 12 It has been established that electrons required for metronidazole activation are released from pyruvate by the activity of __________________ and transferred to the drug by a low-redox-potential carrier, ferredoxin. A. nitroredductase-dependent activation ✓B. pyruvate:ferredoxin oxidoreductase C. ferriprotoporphyrin IX D. oxidative membrane damage Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 13 Match the following antitubercular drugs (numerical) with their most common side or adverse effects (alphabetical) as given below (scroll down to see). Use only the UPPER CASE alphabet (A-D) for your answer 1. Ethambutol 1 2. Isoniazid 2 3. Pyrazinamide 3 4. Rifampin 4 A. Peripheral neuropathy B. Hepatitis C. Harmless orange disoloration of body fluids D. Optic neuritis 1. D|D.| 2. A|A.| 3. B|B.| 4. C|C.| Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 14 Metronidazole is indicated for the treatment of: SELECT ALL Four. ✓A. Amoebic dysentery due to Entamoeba histolytica ✓B. Giardiasis due to Giardia lamblia ✓C. Bacterial vaginosis due to Trichomonas vaginalis ✓D. Antibiotic-associated enterocolitis due to Clostridium difficile E. Malaria due to Plasmodium Falciparum Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 15 Excystation occurs in which of the following organs: ✓A. Small intestine B. Large intestine C. Spleen D. Liver Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 16 When a malarial parasite infects a red blood cell, its presence can be detected by the existence of a parasite protein on the cell’s surface. The immune system can then learn to recognize this protein and develop weapons to eliminate the infected red blood cells. Which of the following statements are correct with regard to malarial parasites’ ability to fool our immune system in recognizing and eliminating the infected RBC? SELECT ALL THAT APPLY. ✓A. The parasites are capable of quickly changing the immunological signature of this cell surface protein ✓B. The parasites have developed an effective and unique method to select the expression of one or another of the var genes at will, that encodes the cell surface proteins. ✓C. The protein shown on the surface of the red blood cells is produced by a family made up of around sixty genes, called var genes. D. Plasmodium falciparum cannot express the var genes and so are not able to fool our immune system. Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 17 What is the mechanism of non-bloody diarrhea caused by Giardia Lamblia? ✓A. Inhibition of absorption by adherence of the parasite to the enterocyte glycocalyx epithelium B. Invasion of the gastroepithelial lining blood vessels C. Inhibition cAMP synthesis D. Hyperperistaltic movement Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 18 The life cycle of malarial parasites, as given in the schematic representation, applies to which of the following malarial parasite species? SELECT ALL THAT APPLY. A. Plasmodium falciparum ✓B. Plasmodium ovale ✓C. Plasmodium vivax D. Plasmodium malariae Attachment: Malarial life cycle.jpg Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 19 Recurrent malaria due to immunodeficiency, such as from corticosteroids, stress, or chemotherapy differs from the type that is usually seen in the immunocompetents. It is because the organisms did not come from the hypnozoite stage, but rather from an erythrocytic stage. This type of malaria is which of the following? A. Relapsing ✓B. Recrudescent C. Refractory D. Dormant Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 20 Patients with active tuberculosis and without a history of prior therapy are started: (SATA) A. with either rifampin or isoniazid mono-drug therapy B. on two-drug therapy to reduce adverse effects ✓C. on a three-drug regimen without ethambutol, If isoniazid resistance is rare ✓D. on a four-drug regimen (without streptomycin) if the local prevalence of isoniazid resistance is greater than 4% Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 21 Peripheral neuropathy is due to competitive inhibition by INH of pyridoxine in neurotransmitter synthesis and can be prevented by ______________ supplementation A. niacin B. riboflavin C. retinoic acid ✓D. pyridoxine Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 22 Prolonged medication with suppressive doses occasionally causes all the following side effects. Which of the following could lead to a medical emergency? A. blurring of vision, and diplopia B. headache, and confusion C. bleaching of hair ✓D. widening of the QRS interval, and T-wave abnormalities Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 23 Pyrazinamide is a prodrug; it must be converted to its active form, pyrazinoic acid, by the enzyme pyrazinamidase. It acts by ✓A. inhibiting FAS1, the enzyme that synthesizes the fatty acid precursors of mycolic acid B. inhibiting FAS2, the enzyme that synthesizes the fatty acid precursors of mycolic acid C. decreasing arabinogalactan synthesis by inhibiting the arabinosyl transferase D. inhibiting bacterial RNA synthesis Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 24 The mechanism of action of Isoniazid is to: A. decrease arabinogalactan synthesis by inhibiting the arabinosyl transferase ✓B. target the FAS2 complex and inhibit mycolic acid synthesis C. target the FAS1 complex and inhibit mycolic acid synthesis D. inhibit bacterial RNA synthesis by binding with DNA-dependent RNA synthesis Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 25 The mechanism of action of Ethambutol is to: A. target the FAS2 complex and are bactericidal ✓B. decrease arabinogalactan synthesis by inhibiting the arabinosyl transferase C. Inhibit mycolic acid synthesis D. bind with DNA-dependent RNA polymerase and inhibit RNA synthesis Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 26 When initially introduced, chloroquine was a first-line drug used against all types of malaria; however, it is now ineffective against most strains of P. falciparum in Africa, Asia, and South America. This is predominantly because of the following reasons: SATA ✓A. mutations in PfCRT probably pumps protonated chloroquine out of the food vacuole ✓B. accumulation of less chloroquine inside food vacuoles than chloroquine-sensitive plasmodia ✓C. second mutation provides a “corrective” action that allows chloroquine-resistant P. falciparum to continue growth in the presence of a pfcrt mutation D. extensive tissue sequestrations lead to suboptimal therapeutic plasma concentration Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 27 Which are the five first-line agents used to treat tuberculosis? A. Ethambutol, ✓B. Ethambutol, C. Ethambutol, Cycloserine Isoniazid (INH), Tetracycline, and Streptomycin Pyrazinamide, Isoniazid (INH), Rifampin, and Streptomycin Cycloserine Isoniazid (INH), Doxycycline, and Paraaminosalicyclic acid (PAS) D. Ethambutol, Cycloserine Isoniazid (INH), Gentamycin, and Paraaminosalicyclic acid (PAS) Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 28 Which of the following statements are correct about Rifampin? SATA (select all four) ✓A. It can kill organisms that are poorly accessible to many other drugs, such as intracellular organisms ✓B. It readily penetrates most tissues and penetrates into phagocytic cells C. Rifampin is bacteriostatic for mycobacteria ✓D. Human RNA polymerase does not bind rifampin and is not inhibited by it ✓E. It can kill organisms that are sequestered in abscesses and lung cavities Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 29 Which of the following statements are correct regarding Isoniazid? SATA (select all three) ✓A. Isoniazid is readily absorbed from the gastrointestinal tract ✓B. Isoniazid diffuses readily into all body fluids and tissues ✓C. The concentration in the central nervous system and cerebrospinal fluid ranges between 20% and 100% of simultaneous serum concentrations D. The dose need not be adjusted in renal failure Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 30 Which of the following is the mechanism of action of chloroquine? A. Inhibits pyruvate-ferredoxin oxidoreductase B. Breaks DNA strands ✓C. Inhibits the polymerization of heme metabolism D. Decreases arabinogalactan synthesis by inhibiting the arabinosyl transferase Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 31 Which of the following statements are correct about Atovaquone? SATA ✓A. Disrupts plasmodial electron transport B. It is most often used as a single-agent ✓C. Can be coadministered with doxycycline or proguanil (Malarone*)(synergistic activity) ✓D. Atovaquone (+ proguanil = Malarone) Rationale: Is not used as a single agent because resistance can occur easily by point mutation Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 32 Which of the following drugs is a tissue schizonticide used to prevent relapse of Pasmodium vivax infections? A. Lumifantrine B. Chloroquine C. Mefloquine ✓D. Primaquine E. Proguanil Item Weight: 1.0 Item Creator: [email protected] ____________________________________________________________________________ Question #: 33 Match the following qualifying antimalarial drugs for prevention in travelers (numerical) with their corresponding situations (alphabetical) as given below (scroll down to see). Use only the UPPER CASE alphabet (A-D) for your answer 1. Chloroquine (weekly) remains an appropriate agent for prophylaxis 1 2. Mefloquine (weekly) 2 3. Either Doxycycline or Malarone (atovaquone plus proguanil); both drugs must be taken daily 3 4. Primaquine (daily for 14 d) or tafenoquine (single dose) is recommended 4 A. for terminal prophylaxis of P vivax and P ovale infections and is an alternative in primary prevention B. in regions with P falciparum resistance to chloroquine C. in areas with multidrug-resistant malaria D. in regions without resistant P falciparum 1. D|D.| 2. B|B.| 3. C|C.| 4. A|A.| Item Weight: 1.0 Item Creator: [email protected]