Trichomonas vaginalis, normally pear-shaped, flattens itself out after attaching to vaginal epithelial cells, maximizing surface area between parasite and host. The purple rod-shaped organisms are bacteria. Image courtesy of Antonio Pereira-Neves and Marlene Benchimol, Santa Ursula University, Rio de Janeiro, Brazil
Most sexually transmitted infections are caused by viruses or bacteria. STIs caused by viruses include herpes and genital warts, and the viruses that cause them aren’t even technically living organisms – they are pieces of genetic information that are able to infect a host cell. STIs caused by bacteria include gonorrhea and syphilis; bacteria are microscopic, single-celled organisms with relatively simple cell structures.
But some STIs are caused by other types of living organisms. Protozoan organisms are microscopic and unicellular, like bacteria; unlike bacteria, their cell structures more closely resemble that of the so-called “higher” life forms such as animals and plants. While protozoa are considered to be “animal-like,” they are not animals at all – they are single-celled organisms that reproduce asexually. When certain types of protozoans get into your body, they can cause infections – such as trichomoniasis, the most common curable STI among young females (as well as more females over 40 than previously thought). It is estimated that 7.4 million new cases of trichomoniasis occur annually in the United States; worldwide, there are about 170 million cases each year.
Trichomoniasis, colloquially known as trich, is spread by vaginal or anal intercourse, direct vulva-to-vulva contact, and other activities that involve passing secretions from one partner to another (e.g., sharing sex toys or mutual masturbation). Sexually active people can reduce the risk of contracting trichomoniasis by using latex barriers, such as condoms. Continue reading
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Tagged bacteria, discharge, flagella, flagellum, HIV, immune system, latex barriers, metronidazole, parasite, parasites, protozoa, protozoans, sexually transmitted disease, sexually transmitted diseases, sexually transmitted infection, sexually transmitted infections, STD, STDs, STI, STIs, T. vaginalis, tinidazole, trich, Trichomonas vaginalis, trichomoniasis, trichomonosis, urogenital tract, vaginal discharge
Treponema pallidum, the causative agent of syphilis, is seen in this electron micrograph adhering to a surface with the end of its structure. Image: Public Health Image Library, CDC
When syphilis first descended upon Europe, it was seen as a new plague, and anxiety and blame coalesced around this mysterious scourge. Was it a punishment from God? Was it introduced by a hated Other? Was it caused by the stars’ alignment or the presence of “bad air”? The panic it provoked foreshadowed the hysteria that surrounded the emergence of HIV in the 1980s, as syphilitics were discriminated against, feared, or thought to have received punishment for their “unbridled lust.”
We now know that syphilis is not caused by supernatural forces, foreigners, or “bad air,” but rather by a species of spiral-shaped bacteria called Treponema pallidum, which can cause infections in the vagina, anus, urethra, or penis, as well as the lips and mouth. It is mostly spread by sexual contact – vaginal or anal intercourse, as well as oral sex – in which one person comes into contact with a syphilis sore. These sores can be hidden on the cervix or in the vagina, urethra, rectum, or mouth, making it not immediately apparent that one is infected with syphilis. Syphilis can also spread to a fetus during pregnancy. Sexually active people can reduce their risk of contracting syphilis by using latex barrier methods such as condoms or dental dams. Continue reading
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Tagged antibiotic, antibiotics, antigenic variation, arsenic, bacteria, chancre, Great Pox, gummatous syphilis, latent syphilis, lesion, lesions, malaria, malaria therapy, mercury, Neosalvarsan, Paul Ehrlich, penicillin, primary syphilis, Salvarsan, secondary syphilis, sexually transmitted disease, sexually transmitted diseases, sexually transmitted infection, sexually transmitted infections, spirochete, STD, STDs, STI, STIs, syphilis, T. pallidum, tertiary syphilis, Treponema pallidum, ulcer
Sexually transmitted infections can be caused by viruses, bacteria, protozoans, and even animals. Bacterial vaginosis and chancroid are both infections caused by bacteria, which means that they can be treated with antibiotics. While bacterial vaginosis only affects people with vaginas, chancroid disproportionately affects people with penises. You can seek diagnosis and treatment for bacterial vaginosis and chancroid at a Planned Parenthood health center, as well as health clinics, private health-care providers, and health departments.
Bacterial vaginosis is caused by an imbalance of bacteria species in the vagina. Image: renjith krishnan / FreeDigitalPhotos.net
Bacterial vaginosis seems to be most commonly caused by the bacteria species Gardnerella vaginalis. Scientists aren’t quite sure how this infection is caused, but risk seems to correlate with a change in sexual partners, having multiple sexual partners, douching, or using an intrauterine device; it can also occur in females who have never been sexually active. It is more common in pregnant women. There is no counterpart to this infection in males, although G. vaginalis can be found in their urethras; this raises the possibility that bacterial vaginosis can be sexually transmitted, in which case it could be directly transmitted between two females or indirectly transmitted from one female to another via a male.
Bacterial vaginosis seems to result from an imbalance in the vaginal flora (“flora” is a somewhat fanciful term for the bacteria that live in your body; under normal circumstances they are harmless and even beneficial). Vaginas usually are habitat to a population of bacteria called Lactobacillus, which produce hydrogen peroxide as a byproduct. When the number of Lactobacillus declines, G. vaginalis is able to move in on Lactobacillus’ old territory. The decrease in Lactobacillus and increase in G. vaginalis leads to a rise in the vagina’s pH. The new vaginal environment is less acidic and more alkaline; a vaginal pH of more than 4.5 is one criterion for the diagnosis of bacterial vaginosis. Another symptom includes a vaginal discharge that may smell somewhat fishy. There might also be genital itching or pain during urination. It is also possible not to have symptoms. Continue reading
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Tagged antibiotic, antibiotics, bacteria, bacterial vaginosis, chancroid, circumcision, discharge, douche, douching, erythromycin, G. vaginalis, Gardnerella vaginalis, H. ducreyi, Haemophilus ducreyi, intrauterine device, IUD, Lactobacillus, lesion, lymph node, lymph nodes, metronidazole, pelvic inflammatory disease, PID, pregnancy, pus, sexually transmitted disease, sexually transmitted diseases, sexually transmitted infection, sexually transmitted infections, sore, STD, STDs, STI, STIs, ulcer, uncircumcised, vagina, vaginal bacteria, vaginal discharge, vaginal flora, yogurt
Cranberry products have a reputation for fighting urinary tract infections. But is this reputation deserved? Image: FreeDigitalPhotos net
An increased urge to urinate. A burning sensation when you do. These are two of the signs of a urinary tract infection (UTI), an incredibly unpleasant condition that can seem to come out of nowhere. Anyone can get a UTI, but among adults they are about 50 times more common in females than in males. Certain microorganisms cause these infections, often when bacteria from feces are introduced into the urinary tract. Although symptoms often clear up without medical intervention, it is very important to seek treatment for a persistent UTI because the infection could spread and become much more serious. (If you are or have been sexually active, it is also important to make sure you don’t actually have a sexually transmitted infection.)
Cranberry products – either as juice (sweetened, unsweetened, or blended with other fruit juices) or capsules – are considered by many to be an effective home remedy for UTIs. While cranberries are a well-known and accessible treatment, the evidence for their efficacy is not very strong. Why, then, are they such a popular treatment? It could be due simply to the placebo effect, an amazing phenomenon in which our expectations help shape our experiences. It could be that symptoms often clear up on their own, but we attribute our improvement to whatever remedies we happened to be trying at the time. It could be that drinking extra fluids (e.g., cranberry juice) helps flush the bacteria from our bodies as we urinate more. Or, it’s possible that cranberries do help clear up UTIs, but we just don’t have solid evidence yet. Continue reading
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Tagged antibiotic, antibiotic resistance, antibiotics, bacteria, Cochrane Collaboration, cranberries, cranberry, cranberry capsules, cranberry juice, E. coli, Escherichia coli, fimbriae, folk remedies, folk remedy, home remedies, home remedy, immune response, immune system, inflammation, pili, pilus, placebo, placebo effect, randomized clinical trial, rUTIs, UPEC, urinary tract infection, urinary tract infections, urine, uropathogenic E. coli, UTI, UTIs
Neisseria gonorrhoeae, the bacteria species that causes gonorrhea, is pictured here in a photograph taken with a scanning electron microscope. Projecting from the organism’s surface are many pili, powerful appendages that enable the bacteria to adhere to human cells. Image from the National Institute of Biomedical Imaging and Bioengineering.
April is STD Awareness Month, but this blog has sought to increase your awareness of sexually transmitted infections on a monthly basis. So far in 2011 we’ve pointed the spotlight at human papillomavirus, barrier methods, and herpes. This month’s installment will focus on gonorrhea, colloquially known as “the clap,” a common sexually transmitted infection caused by sneaky bacteria called Neisseria gonorrhoeae. It is spread by vaginal, anal, and oral sex, and can infect certain cells in the throat, mouth, rectum, urethra, or cervix. It can also be transmitted manually to infect the eye. If you are sexually active, you can reduce risk of transmission by consistently and correctly using latex barriers such as condoms and dental dams.
Four out of five females infected with gonorrhea do not experience symptoms – males, however, usually do, but they can be mild and therefore easy to overlook. Symptoms can appear within a month, and might include painful or frequent urination, vaginal or penile discharge, painful bowel movements, itching, or sore throat. Additionally, females can experience abdominal pain, fever, irregular menstruation, or bleeding between periods. In pregnant women, untreated gonorrhea infections can lead to complications such as premature labor or stillbirth. The infection can also be passed from mother to infant during delivery. Continue reading
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Tagged antibiotic resistant gonorrhea, antibiotics, antigenic variation, ARG, bacteria, bacterium, DGI, disseminated gonococcal infection, epididymitis, evolution, fimbriae, flagella, flagellum, GC, gonococci, gonococcus, gonorrhea, HIV, immune response, immune system, microbe, microorganism, N. gonorrhoeae, Neisseria gonorrhoeae, Opa protein, Opa proteins, pelvic inflammatory disease, PID, pili, pilus, retractile pili, sexually transmitted disease, sexually transmitted infection, STD, STI, sulfa drugs, sulfanilamide, sulfonamides, the clap, type IV pili