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Sexually Transmitted Diseases (I)

What are Sexually Transmitted Diseases (STDs)? STDs are diseases that are transmitted via various types of sexual intercourse – including vaginal, oral and anal intercourse. STD infections mostly occur in the genital and anal mucosae. However, they may also infect the eyes, the mouth and pharynx.

Sexually Transmitted Diseases (I)

Scanning electron microscopic (SEM) image of Treponema pallidum bacteria | © CDC/ Dr. David Cox, public domain

Condoms and dental dams are the only ways to prevent infection. It is also important to remember to clean sex toys often, and very carefully between each person. Each day, more than one million people get infected with STDs. Infection with one STD increases the risk to getting infected with another STD. This is one of the reasons why it is crucial to detect and treat them as early as possible. It is always important to recent sexual partners too, to prevent a “ping-pong effect”. It is very highly recommended to wash toys and apply fresh condoms when going from anal to other forms of sex. There are four types of STDs:

  • bacterial
  • fungal
  • viral
  • and parasitic infections.

In this article I am going to focus on the most common bacterial STDs.

Syphilis: What do we know about this STD?

Recently, the rate of syphilis infections in Germany has increased (more than 7,000 cases in 2019). Syphilis is caused by Treponema pallidum, which enters the body via the genital, mouth or anal mucosa and spreads through the blood and lymph vessels. Incubation time is about two to three weeks. Treponema pallidum does not survive for a long time outside the human body, however infections via contaminated towelsdas Handtuch and clothes are possible. Syphilis can be transmittedetw. übertragen from a mother to her unborn child. Condoms are the best possible protection, nevertheless, the ulcers on other body parts are also infectious.

Symptoms: A dark spot at the point of infection which develops into an ulcer, a general feeling of being sick, swelling of the lymph nodes, eczemadas Ekzem, nodulesdas Knötchen. After about four months, the symptoms usually disappear and infected people may be free of symptoms for decades. However, they are still sick, and will pass the disease on to their partners. Ultimately, syphilis can lead to disorders of the nervous system.

Specimen: Exudates will be used from lesions of primary, secondary and early congenital syphilis. Serum is used for nontreponemal and treponemal serological testing. Since Syphilis has several clinical manifestations, laboratory testing is a very important aspect of diagnosis.

Diagnostic tests

  • Microscopy: Treponemes are spirochaete bacteria and mostly gram-negative, which means they have a cytoplasm and an outer membrane. Using light microscopy, treponemes are visible only by dark field illumination.
  • Tests for direct detection of T. pallidum
  • Dark-field microscopy
  • Direct fluorescent antibody test for T. pallidum
  • Direct tests for T. pallidum in tissue sections
  • Nucleic acid amplification methods
  • Nontreponemal Serological Tests
  • VDRL, RPR, USR and TRUST tests
  • Treponemal Serological Tests
  • Fluorescent treponemal antibody absorption test and fluorescent treponemal antibody absorption double staining tests
  • TP-PA test
  • EIA
  • Western blot
  • Rapid tests

Therapy: Syphilis can be treated with penicillin.

Gonorrhea: What do we know about this disease?

Gonorrhea is the third most frequent STD worldwide. Neisseria gonorrhoeae, also known as Gonococci, are the bacteria that cause gonorrhea. It mainly occurs on the mucous membranes of the genitourinary tract (anal canal, pharynx and the conjunctiva). Indirect transmission is improbable. Babies can get infected during birth through the eyes and thus sufferleiden from conjunctivitis and may go blind. Incubation time is one to fourteen days from the infection until the first symptoms.

The symptoms are vaginal and urinal dischargeder Ausfluss, pain during urination, itchingdas Jucken, der Juckreiz and burningdas Brennen, conjunctivitis, a swollen penis or fore-skin. More than every second woman and every tenth man do not show any symptoms.

Consequences if not treated early enough can be infertility (women: due to adherence of the oviductsEileiter, men: adherence of the spermatic cords); gonorrhea might also lead to tubal pregnancydie Eileiterschwangerschaft.

Specimen: Urine probe or cervix smear (women) or urethra (men)

Diagnostic tests

  • Microscopy: Gram-negative diplococci
  • Biochemical testing
  • Detection of acid produced from carbohydrates
  • Enzyme substrate test
  • Nitrate reduction
  • Production of polysaccharide from sucrose
  • DNase

Therapy: Several antibiotics can treat gonorrhea. However, resistant strains of gonococci have recently increased, which is why it is especially crucialentscheidend to determine the exact bacterium causing the disease. Ceftriaxone is currently the last remaining effective antibiotic for the treatment of gonorrhea. Combination therapy with macrolide azithromycin is recommended.

Ulcus molle: What’s known about the disease also called “chancroid“ or “weicher Schanker”?

Ulcus molle is rare in Europe, however, it is common in the (sub-)tropics, Africa, Central and South America and Southeast Asia. Sores form around the spot where Haemophilus ducreyi (one of the pathogens of the haemophilus group) entered the body. Those sores are very painful except when inside the vagina or around the cervix.

Specimen: Pusder Eiter, predominantely from the lymph nodes.

Diagnostic Tests

  • Microscopy: Gram-negative coccobacilli in railroad or chaining arrangements. Because of low sensitivity, microscopy is of limited value.
  • Culture: It is still the “gold standard“. More than one medium should be used. Use a split plate that contains the two types of media. Gonococcal agar supplemented with 2% bovine hemoglobin and 5% fetal calf serum, 1% Isovitalex supplement, 3 μg/ml of vancomycin, and Mueller-Hinton agar supplement with 5% chocolatized horse blood, 1% Isovitalex supplement and 3 μg/ml of vancomycin. This has been shown to be an optimal combina-tion [4]. This should be incubated in 5% CO2 at 33°C to 35°C in a humid environment.
  • Biochemical testing
  • Antigen detection: Direct immunofluorescent testing of ulcerdas Geschwür material is used.
  • Nucleic acid detection (with or without amplification)
  • Serology

Therapy: The disease is treated with antibiotics (Vancomycin) although the bacterium has developed several resistances.



1. Symptoms for Gonorrhea are:

a) Headache
b) Vaginal discharge
c) Pain during urination
d) Conjunctivitis
e) Swollen penis

2. After about four months, Syphilis symptoms disappear, but the infected person is still infectious.

a) True
b) False
3. Ulcus molle is widespread in Europe.
a) True
b) False

You’ll find the answer on the next page.



  4. Alfa M: Can J Infect Dis Med Microbiol. 2005 Jan-Feb; 16 (1): 31–34, DOI: 10.1155/2005/851610.
  5. Kayser FH, Bienz KA, Eckert J, Zinkernagel RM: Medical Microbiology. Thieme Verlag, 2004.


Carmen Lobitz ist freie Trainerin, Lehrerin und MTA. Sie gründete 1998 in Berlin lobitz seminare, die unter anderem Englischseminare für Health Professionals anbieten.


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