Bacterial Infections


Bacteria are single-celled microorganisms that thrive in many different types of environments.1 They are found in every habitat on Earth including soil, rock, water, artic snow, and even the human body.2 In fact, there are approximately ten times as many bacterial cells as human cells in the human body.3 Most types of bacteria are harmless or healthy, and these types of bacteria are responsible for maintaining balance in the natural world. Good bacteria breaks down dead plants and animals, returns carbon to the earth to be used again, and performs many of the necessary tasks required by living organisms to function properly.4 For example, trillions of bacterial cells line the human digestive tract in order to help our bodies digest food.5 However, there are other forms of bacteria that are harmful to living organisms, often referred to as pathogenic bacteria. At low levels, pathogenic bacteria can exist in the body without doing harm. But, if the immune system is weak or the body has low levels of healthy bacteria, pathogenic bacteria can grow, causing unwanted infections and diseases such as cancer, STIs, diabetes, and cardiovascular disease.6

A close up of bacteria

Bacterial Infections

A bacterial infection begins when unhealthy bacteria occupy and multiply inside the body and disrupt healthy function. When unhealthy bacteria outnumber the healthy bacteria, a bacterial infection occurs.4 A found increase in bacterial infections is partially due to the inappropriate use of antibiotics; for example, medical misinformation may lead people to use antibiotics incorrectly, which then encourages the body to kill healthy bacteria6 and grow resistant to future treatment.1 

Bacterial infections may be spread through various ways. Some examples include:

  • Contaminated water
  • Contaminated food
  • Sexual contact
  • Airborne transmission (such as a cough or sneeze)
  • Animal contact
  • Touching infected individuals
  • Spreading from one part of the body to another part (metastasize)

Different types of bacteria spread in different ways; the exact cause of spread is dependent on the type of bacteria.7

Two masked individuals demonstrating how effective masks are at protecting from bacteria

Sexually Transmitted Bacterial Infections

Unhealthy bacteria thrive in warm, moist environments, which is why the genitals, eyes, mouth, and anus are so commonly prone to infection.8 A number of sexually transmitted infections (STIs) are classified as bacterial infections. The most common bacterial STI is chlamydia. Others include gonorrheasyphilisvaginitis, and urethritis.9 These infections are transmitted through any contact, but especially sexual contact, with the mouth, genitals, or anus of an infected person. The infections pass from person to person through blood, semen, or vaginal and other bodily fluids.1 Newborn infants can also contract a bacterial infection in their eyes when passing through the birth canal of an infected mother.10 Some bacterial infections are not transmitted directly through sexual contact. For example, Pelvic Inflammatory Disease (PID) results from an untreated infection in the vaginaUrinary tract infections (UTIs) can result from the presence of bacteria in the urethra due to sexual, or other, activity.

A couple sharing a bed and kissing


Symptoms of sexually transmitted bacterial infections typically include itching and burning during urination, unusual discharge or odor from the affected area, pain in the abdomen or back, and pain during intercourse. The absence of these symptoms does not always indicate that a person is free of infection; STIs are often asymptomatic, especially in women.1

Treatment and Prognosis

In general, bacterial infections can be easily and quickly treated with antibiotics. However, if they are not treated promptly, there may be severe consequences. Infections of the reproductive system can lead to chronic pain, infertility, and even death.11 There is also possibility of the infection becoming resistant to antibiotics, such as the case of super gonorrhea, a bacterial mutation of gonorrhea that was found to be completely resistant to antibiotic treatment.  Antibiotic-resistant bacterial infections can be difficult and sometimes impossible to treat. These types of infections can require extended hospital stays, multiple follow-up visits, and are very costly and toxic to treat.9 The best way to protect against antibiotic resistance is to never share prescribed medicine, to take the antibiotics exactly as prescribed, and to finish the antibiotic prescription even if symptoms have reduced.9 


The risk of contracting a sexually transmitted bacterial infection can be significantly lowered by practicing safe sexCondoms, when used correctly and consistently, are the only contraceptive method that provides substantial protection against STIs. If sexually active, it is recommended to get tested for STIs often, approximately every three months, and to honestly communicate with medical professionals about sexual activity. Avoid sexual contact with infected individuals until they have been completely treated of their bacterial infection and communicate with all potential partners about history and treatment of STIs. Prevention of bacterial infections also includes maintaining healthy hygiene habits, such as washing one’s hands frequently, especially after sexual activity of any kind; this will help stop the spread of bacteria. For people with vaginas, the use of douches or scented soaps inside and around the vagina will disturb the body’s natural balance of healthy bacteria, so to prevent bacterial infections, these hygiene methods are not recommended.

For more information on bacterial STIs, you may visit the following articles:

·      Chlamydia

·      Syphilis

·      GonorrheaSuper gonorrhea

·      Vaginitis

·      Nongonococcal Urethritis

·      Pelvic Inflammatory Disease

In addition, this STI symptom chart offers a comprehensive overview of all sexually transmitted infections.12

Two unused condoms

Concluding Remarks

Both healthy and unhealthy bacteria are everywhere, and with the rise of antibiotic resistance, such as the case of “super gonorrhea,” it is crucial that we are educated on safe sex practices, treatment, and general prevention of bacterial infections. Thus, this article aims to provide sufficient advice and evidence pertaining to sexually transmitted bacterial infections and their relationship to sexual health. If you or anyone you know is experiencing symptoms of a bacterial infection, we recommend contacting a medical professional for further testing and possible treatment.


  1. Mayo Foundation for Medical Education and Research. (2020, November 14). Infection: Bacterial or viral? Mayo Clinic.
  2. Microbiology Society. (n.d.). Bacteria: What is microbiology? What is microbiology? | Microbiology Society.
  3. Wenner, M. (2007, November 30). Humans Carry More Bacterial Cells than Human Ones. Scientific American.
  4. “Human Diseases and Conditions.” Human Illnesses and Behavioral Health, n.d. Web. 26 Jan. 2015.
  5. Doron, S., & Gorbach, S. L. (2008). Bacterial Infections: Overview. International Encyclopedia of Public Health, 273–282.
  6. Yttri, J. (2017, March 28). Bacteria: The Good, the Bad, and the Ugly. National Center for Health Research.
  7. Santos-Longhurst, A. (2019, April 3). What is a Pathogen? 4 Types and How They Spread Disease. Healthline.
  8. Cellulitis. Johns Hopkins Medicine. (n.d.).
  9. Centers for Disease Control and Prevention: CDC. (n.d.). Sexually Transmitted Diseases (STDs).
  10. Neonatal Infections. Home – Johns Hopkins All Children’s Hospital. (n.d.).
  11. Urology Care Foundation. (n.d.). Sexually Transmitted Infections. Sexually Transmitted Infections: Symptoms, Diagnosis & Treatment – Urology Care Foundation.
  12. LeVay, Simon, Janice I. Baldwin, and John D. Baldwin. “Sexually Transmitted Diseases.” Discovering Human Sexuality. 2nd ed. Sunderland, MA: Sinauer Associates, 2012. 469. Print.

Last Updated: 27 May 2021