Ciprofloxacin gastrointestinal infections

Answer C In amebic dysentery caused by Entamoeba histolytica and gastrointestinal infections with diarrhea ( backpackers diarrhea ) due to Giardia lamblia, metronidazole is the drug of choice. Diloxanide is a backup drug for noninvasive intestinal amebiasis, but it has minimal activity in Giardia infections. Quinacrine has effectiveness in giardiasis but not amebiasis. TMP-5MX has antiprotozoal effectiveness in Pneumocystis carinii pnemnonia. Ciprofloxacin is devoid of antiprotozoal activity. 

The breakthrough in the development of quinolones came with the appearance of norfloxacin 6 [19], a second-generation quinolone which combined a 6-fluorine substituent with a piperazine ring in the 7-position of the basic compound. Additional quinolones then followed in rapid succession pefloxacin [20], enoxacin [21] and fleroxacin [22] (Fig. 14.5). Particular mention must be made of ciprofloxacin 8 [23-25], ofloxacin 5 [26,27] and its active enantiomer levofloxacin 7 [28]. These quinolones have a broad spectrum of activity, which also includes Gram-positive bacteria and Pseudomonas aeruginosa, as well as favorable pharmacokinetics. The rapid absorption of these compounds from the gastrointestinal tract and their effective tissue penetration also allows them to be used for the treatment of systemic infections. 

As patients improve clinicaUy, the route of administration should be reevaluated. Streamlining therapy from parenteral to oral (switch therapy) has become an accepted practice for many infections outside the bloodstream and CNS. Criteria that should be present to justify a switch to oral therapy include (1) overall clinical improvement, (2) lack of fever for 24 to 48 hours, (3) decreased WBC count, and (4) a functioning gastrointestinal tract. Drugs that exhibit excellent oral bioavaUabifity when compared with intravenous formulations include ciprofloxacin, clindamycin, doxycycline, gatifloxacin, levofloxacin, metronidazole, moxifloxacin, linezolid, and trimethoprim-sulfamethoxazole. 

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