Ciprofloxacin is an antibiotic, and only kills certain types of bacteria. Sexually transmitted diseases (STDs) can be caused by a variety of infections, of which bacteria only make up a portion. Of the bacterial infections that medical professionals have previously used ciprofloxacin to treat, some have become resistant to the drug, so other antibiotics may be necessary. As of 2011, chancroid and the primarily tropical STD granuloma inguinal are considered treatable by the drug.
When an STD is caused by a virus, ciprofloxacin is not effective. STDs caused by viruses include genital herpes, human immunodeficiency virus (HIV), and genital warts. Viruses do not typically respond to antibiotics.
Each antibiotic also has specific modes of action, and therefore cannot target all bacterial species. For example, chlamydia is caused by the bacterium Chlamydia trachomatis, which ciprofloxacin cannot target. Ciprofloxacin is also ineffective against lymphogranuloma vereneum, which is also caused by C. trachomatis.
Other bacterial diseases that ciprofloxacin cannot treat include syphilis, where the bacterium Treponema pallidum causes the illness. Bacterial vaginosis is another condition, which may or may not be produced by an STD. This condition also does not typically respond to a treatment that includes ciprofloxacin. Trichomoniasis also does not clear up with ciprofloxacin, but in this case it is because the causative agent is a protozoan parasite and not a bacterium.
Bacteria can evolve over time and develop resistance mechanisms to an antibiotic, and ciprofloxacin is no exception. The Centers for Disease Control (CDC) in the United States issued a statement in 1998 indicating that ciprofloxacin was one of the effective treatments for gonorrhea, but by 2010, the bacterium that causes gonorrhea was so resistant to this drug that the CDC recommended using other drugs, such as ceftriaxone, instead.
According to the 2010 CDC recommendations on STD treatment options, ciprofloxacin is only suitable for treating chancroid and a disease that primarily occurs in tropical countries called granuloma inguinale. In the case of this disease, the causative bacterium is Klebsiella granulomatis. Even though ciprofloxacin, as of 2011, can treat these diseases, sometimes problems occur.
With chancroid, there are some strains that are resistant to the drug. With these specific cases, other drugs, like azithromycin, may be able to treat the infection successfully. Granuloma inguinale also has a tendency to recur, even though the initial antibiotic treatments appear successful. Another drawback to using ciprofloxacin for STDs is that it is not safe for pregnant and breastfeeding women.