Sexual transmitted infectious agents

Sexually transmitted diseases (STD) constitute a significant problem worldwide for medicine and for public health authorities. In addition to the classic sexual diseases such as gonorrhoea, syphilis, and venereal ulcers, infections with bacterial vaginosis and non-gonococcal urethritis (NGU), if not diagnosed and treated properly, can lead to complications such as infertility, extrauterine pregnancy, or severe effects on pregnancies and newborns. 

Chlamydia trachomatis

Chlamydiae are gram-negative, immobile bacteria that are unable to synthesize ATP and, thus, exist as obligate intracellular parasites in eukaryotic cells. There are four known species of Chlamydia: C. trachomatisC. psittaciC. pecorum and C. pneumoniae (TWAR). C. psittaci and C. pecorum are primarily animal pathogens.

Today, C. trachomatis is regarded as the second most common causative agent of sexually transmitted diseases with about 89.1 million infections worldwide each year. About 3 million cases are registered each year in the United States. It is known that C. trachomatis can cause cervicitis, adnexitis, neonatal conjunctivitis, neonatal pneumonia, urethritis, epididymitis and proctitis. Moreover, C. trachomatis is the most frequent cause of nongonorrhoeal urethritis in men (ca. 25 – 55 % of the cases).

Untreated chlamydial infections in women can lead to serious consequences. Because approximately three-fourths of these infections are asymptomatic, many cases remain unrecognized and untreated, which causes additional problems especially in pregnant women. Newborn children of women infected with chlamydia have a high risk for inclusion conjunctivitis and pneumonia. 

Neisseria gonorrhoeae

Neisseria gonorrhoeae (gonococcus) is the pathogen that causes gonorrhoea. N. gonorrhoeae are gram negative diplococci that are cytochrome oxidase-positive, nonmotile and non-spore forming. N. gonorrhoeae is genetically closely related to N. meningitidis (meningococcus), the cause of one type of bacterial meningitis. N. gonorrhoeae is more distantly related to N. lactamica, which is occasionally pathogenic to humans. Both N. gonorrhoeae and N. meningitidis infect only humans. In addition, there various species of Neisseria that belong to normal human flora; these include N. cinereaN. elongataN. flavescens, N. mucosa, N. sicca and N. subflavaN. gonorrhoeae infections are the third most frequent cause of sexually transmitted diseases. Worldwide about 62.2 million cases of gonorrhoea are reported yearly. In men, this disease generally causes urethritis of the lower urethra with purulent discharge. In women, the disease is usually localized to the cervical area, but the vagina and uterus can also become infected. 

Сексуално преносливи микоплазми

Mycoplasmas are the smallest, self-replicating micro-organisms (diam. 300-800 nm depending on cell shape). Since they have no cell wall, they are resistant to many antibiotics, very variable in shape, and difficult to identify using staining techniques.

Some species occur as animal and human parasites and multiply in these hosts. The most important human pathogen species include Mycoplasma hominisUreaplasma urealyticum and Mycoplasma genitalium, in addition to Mycoplasma pneumoniae. They colonize the mucosa of the urogenital tract and are the source of a variety of diseases when they overmultiply.

Organisms of the species Mycoplasma hominisMycoplasma genitalium, and Ureaplasma urealyticum are a common causative agent of STDs in both men and women. Asymptomatic infections are frequent in women, while up to 70% of men present with symptoms such as urethral disorders, dysuria, penis irritation, and signs of epididymo-orchitis or prostatitis.

The following disorders caused by mycoplasmas and ureaplasmas have so far been identified in women:

– Inflammation of the bladder (cystitis)

– Inflammation of the urethra (urethritis)

– Inflammation of the kidneys and renal pelvis (pyelonephritis)

– Inflammation of the vagina (vaginitis, colpitis)

– Inflammation of the cervical mucosa (cervicitis)

– Inflammation of the uterine tube (salpingitis)

– Inflammation of the Fallopian tubes and ovaries (adnexitis),

– Inflammation of the pelvic connective tissue and uterine mucosa (parametritis and endometritis).

In men, mycoplasma and ureaplasma infections can lead to inflammation of the urethra (urethritis) and the prostate (prostatitis). 

In both sexes, such infections may induce infertility. In addition, Mycoplasma hominis and Ureaplasma urealyticum can cause postpartum pneumonia, meningitis, and abscess formation in newborns. 

Treponema pallidum

Treponema pallidum subsp. pallidum belongs to the Spirochaetes phylum and is the causative agent for Syphilis. The bacterium is approximately 5 – 15 μm in length and 0,2 μm width, with a helical shape.

Syphilis occurs only in humans and is transmitted by sexual contact, via blood or intrauterine from mother to child. Reported syphilis cases in Germany have been increasing during the last years, the highest incidence was observed in men in the age group 30 to 39. In 2015, 28 701 syphilis cases were reported in 29 EU/EEA Member States, at a rate of 6.0 per 100 000 population. In Germany, congenital syphilis is reduced by mandatory screening due to the German Maternity Guidelines to a few individual cases, but up to 1 million cases of congenital syphilis are estimated world-wide (WHO).

T. pallidum infection progresses through several stages if untreated: Primary; secondary; latent and tertiary. Primary infection presents in a chancre lesion at the site where the bacteria penetrate the epithelial cells. Multisystem involvement, general, skin or mucosal symptoms can follow. If left untreated, the latent stage of the infection follows for one year up to decades. If an inflammatory reaction develops (late or tertiary syphilis), gummatous skin lesions may occur. At this stage, T. pallidum can also affect the cardiovascular system and the central nervous system (neurosyphilis). In cases of HIV coinfection, more atypic and severe courses of infection may occur, the period of latency can be strongly shortened, symptoms of several stages may arise simultaneously.

Avicena Laboratory has high sensitivity tests for molecular detection of pathogens which cause sexually transmitted infections and bacterial vaginosis.