Protozoa metronidazole activity

The answer is e. (Hardman, pp 995-998.) Metronidazole is a low-molecular-weight compound that penetrates all tissues and fluids of the body. Metronidazole s spectrum of activity is limited largely to anaerobic bacteria-—including B./ragihs—and certain protozoa. It is considered to be the drug of choice for trichomoniasis in females and carrier states in males, as well as intestinal infections with CAardia lamblia. 

Pharmacology Metronidazole, a nitroimidazole, is active against various anaerobic bacteria and protozoa. It is believed to invoke cytotoxicity on the reduced nitro group in the bacterium cell. The liberated inactive end products are believed to target the RNA, DNA, or cellular proteins of the organisms. 

Metronidazole Flagyl, Metrogel) exerts activity against most anaerobic bacteria and several protozoa. The drug freely penetrates protozoal and bacterial cells but not mammalian cells. Metronidazole can function as an electron sink, and because it does so, its 5-nitro group is reduced. The enzyme, pyruvate-ferredoxin oxidoreduc-tase, found only in anaerobic organisms, reduces metronidazole and thereby activates the drug. Reduced metronidazole disrupts replication and transcription and inhibits DNA repair. 

A few antimicrobials have useful activity across several of these groups. For example, metronidazole inhibits obligate anaerobic bacteria (such as Clostridium perfringetis) as well as some protozoa that rely on anaerobic metabolic pathways (such as Trichomonas vaginalis). 

Uses. Metronidazole is active against a wide range of anaerobic bacteria and also protozoa. Its clinical indications are ... 

Mechanisms Metronidazole is an imidazole derivative with activity against protozoa and bacteria. The drug undergoes a reductive bioactivation of its nitro group by ferredoxin (present in anaerobic parasites) to form reactive cytotoxic products that interfere with nucleic acid synthesis. 

The following anti-trypanosomal drugs bind irreversibly to, and disintegrate, the kinetoplast of Trypanosoma rhodesiense (in the mouse) without any effect on the cell s nucleus diminazine, ethidium, pentamidine, hydroxystilbamidine, and trypaflavine (Macadam and Williamson, 1972). The lack of a histone covering over the kinetoplast makes it more vulnerable than the nucleus to these drugs (Steinert, 1965). In place of mitochondria, some protozoa have hydrogeno-somes in which ferredoxin-activated enzymes, which convert pyruvate to acetyl-CoA, are selectively vulnerable to metronidazole. 

Tinidazole is chemically l-(2-ethylsulfonyl-ethyl)-2-methyl-5-nitroimidazole (Figure 1). It is active against protozoa and anaerobic bacteria and is used like metronidazole in a range of infections [1]. The drug is reported to hydrolyze quantitatively in alkaline conditions to 2-methyl-5-nitroimidazole and under photolytic conditions, the drug yields intermediate, rearrangement, and degradation products [2]. 

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