Bacterial Sexually Transmitted Infections

Bacteria are living single-celled organisms which do not contain a true nucleus (they are prokaryotes), do not contain organelles (compartments seen in animal and plant cells associated with a specific function), yet possess a 'fatty' cellular membrane and an outermost tough cell wall[1]. Bacteria are responsible for the presence of conditions suitable for human life and some are essential to industry, the environment and even human functioning (with more than half of the human body weight actually belonging to bacterial cells, they are responsible for digestion of many ingested materials)[1]. However, some species of bacteria have developed to infect other forms of life (including humans), and as a result of their growth may cause disease in the host (ranging from asymptomatic, mild and moderate through to severe signs and symptoms)[1]. Diseases caused by bacteria are usually temporary and can often be cured (complete elimination of the pathogen) with the use of antibiotics to assist the immune system, although certain species may cause a rapid decline and death before antibiotics can be given, some may be resistant to common antibiotics and some may cause long-term side effects long after the infection has been cleared (as a result of autoimmune damage or disabled tissue repair)[1].

Gonococcal Urethritis
Gonorrhoea refers to the (sexually transmitted) infection of any mucosal membrane of the body by Neisseria gonorrhoeae. After a short incubation time, acute clinical symptoms appear in 95% of men ('burning' pain upon urination and unusual discharge from the penis after 2-8 days) and 30% of women ('burning' pain upon urination, frequent urination, unusual discharge from the vagina, including unusual bleeds, abdominal pain and fever after 7-21 days)[1,2,3]. Approximately 100 million new cases appear every year worldwide, with ≈30-40 million individuals infected at any given time, and infection rates are rising[2]. Gonorrhoea is the second-most commonly notified STI in WA, with ≈2000 cases each year (≈50% of which are in the 15-24 age bracket)[4].
WA rates among Aboriginal individuals are forty times higher than among non-Aboriginal people[4].

Source: WA DoH (http://www.public.health.wa.gov.au/3/1549/3/gonorrhoea.pm)

Without early treatment and cure in females, severe infection of the reproductive tract may lead to Pelvic Inflammatory Disease, associated with scarring and a loss of function (sometimes ) in 40% of infected females and infertility in 10%[2]. Furthermore, this scar tissue may also prevent the ability of a fertilised egg to reach the normal implantation site in the womb, therefore allowing the potentially fatal syndrome (requires urgent emergency surgery) of ectopic pregnancy, a potentially fatal syndrome [2,3]. Similarly, males can develop infection and swelling and/or scarring of the reproductive tract, which is also a (rare) cause of infertility[1,2,3].

Other forms of gonoccocal infection include;

• Disseminated gonococcal disease, which produces an acute fever, chills, muscle and joint pain and skin lesions due to the presence of bacteria in the blood. This occurs in less than 1% of infected individuals and may eventually lead to gonococcal arthritis (painful inflammation of the joints), gonococcal endocarditis (eventually leading to heart failure) and infection of numerous body sites (including the throat and other soft surfaces)[1].
• Ophthalmia neonatorum (conjunctivitis of the newborn) is a result of transmission from an infected pregnant mother to the foetus during childbirth (does not pass through the placenta); treatment with antibiotics upon delivery may prevent infection, and prevent 4000 cases of neonatal blindness every year[2].

Detection typically involves swabs of the male urethra (also urine test), female endocervix, rectum, mouth, throat, eyes and blood and laboratory analysis[3]. Due to the increasing prevalence of antibiotic resistance (Neisseria species have extremely efficient mechanisms of adaption and evolution), many antibiotics are now becoming often ineffective and hence sensitivity testing (identifies appropriate antibiotic treatment) is essential[1]. Given some strains show resistance to all currently-available antibiotics (extreme drug-resistant strains), those infected cannot be cured, and is vital that the full course of administered antibiotics be taken in individuals (to prevent further resistance). Vaccines, while under intensive research, are currently unsuccessful[1].

If infected, sexual contact must be avoided (until the infection is cleared) to prevent transmission to others, particularly if infected with drug-resistant strains (extremely difficult and expensive to treat), as transmission from males to females is ≈20% successful per act of intercourse[2].

Non-Gonococcal Urethritis (NGU)
Chlamydia (caused by the Chlamydia trachomatis bacteria) is the most common STI in developed countries such as Australia, and is the leading global cause of non-gonococcal urethritis (NGU) worldwide[1,4]. Every year, ≈100 million are newly infected, with a similar number infected at any given time[2]. While infection is usually asymptomatic (no signs or symptoms) in 40% of males and 85% of females, the common symptoms include 'burning' pain during urination, pain in the groin (particularly during sex), unusual discharge from the vagina or penis, joint pain and unusual vaginal bleeding (such as in-between periods)[1,2,5]. Chlamydia infection is the leading STI in WA with ≈11,800 notifications per year, with ≈60% of cases occurring within the 15-24 age bracket[4]. WA rates among Aboriginal individuals are five times higher than among non-Aboriginal people[4].

Source: WA DoH (http://www.public.health.wa.gov.au/3/1539/3/chlamydia_genital.pm)

Without early treatment and cure, severe infection of the female and male reproductive tract may lead to Pelvic Inflammatory Disease and infertility (as seen in Gonorrhoeal infection)[1,2,5]. Furthermore, infection with Chlamydia dramatically increases the risk of getting other STIs[2]. Infection during pregnancy may cross the placenta and produce either significant malformations or death of the foetus[1].

Another severe form of infection is called Lymphogranuloma Venerum and results from an invasive strain of C. trachomatis. Rare in developed countries (yet common in tropical regions of the world), it is associated with painful swollen glands and disfigurement of genitalia approximately 3-30 days after exposure (before producing severe brain and liver effects)[1,6].

Chlamydia can be detected with a simple urine test in men and an additional vaginal swab in women, and is treated with a course of antibiotics (some of which are ineffective if alcohol is consumed during treatment) early in infection[5]. PID is more difficult to treat, as the damage is often irreversible. the full course of treatment and follow-up testing must be taken to make sure an individual is clear of infection, and sexual contact should be avoided (even with normally 'effective' protection) until cured to prevent transmission, as male-to-female transmission rates are ≈40% per act of sexual activity[2].

Mycoplasma genitalium, Mycoplasma hominis and Ureaplasma urealyticum are other minor causative agents of NGU and may eventually lead to PID, as more commonly seen in infection with Chlamydia 5]. Detection occurs through a simple urine test and these infections may be easily treated with a short course of second- or third-generation Macrolide, Tetracycline and/or Cephalosporin antibiotics.[1,5].

Syphilis

Syphilis is another common STI resulting from infection withTreponema pallidum, a species of spirochaete (has a unique coiled/helical shape). With ≈10 million new cases of infection every year, 30-40 million people worldwide are infected at any given time, with ≈80 case notifications per year in WA[2,4].

Source: WA DoH (http://www.public.health.wa.gov.au/3/1564/3/syphilis_infectious.pm)

Infection occurs in four main stages;

• The primary phase is associated with the presence of a small, hard but painless ulcer (a chancre) at the site of infection after approximately 10-20 days[1,7]. Not only is this chancre lesion infectious, but bacterial entry into circulation (blood and lymph) allows spread via blood-to-blood contact[1,7].
• The secondary phase is characterised by the development of infectious rashes (often on the palms of hands, face and soles of feet), patchy hair loss and swollen glands approximately 2-10 weeks after the appearance of the chancre[1,7]. Less common signs include fever, sore joints and muscles[7].
• After several weeks the infection goes 'silent' (latent)[6]. While the person is not usually infectious following sexual or blood contact, if the woman falls pregnant congenital syphilis may result[1]. Congenital syphilis is spread through the placenta at any time in pregnancy, and can lead to abortion (25% in untreated syphilis), premature delivery, significant congenital malformation and neonatal conjunctivitis, pneumonia and/or death (14% in untreated syphilis)[2].
• The tertiary phase may then develop in about 40% of individuals following many years of latent infection[1,7]. This is associated with the formation of large, rubbery degenerative lesions called gummas in the skin, bone, heart and brain[1,7]. These may lead to reduced cognitive ability, blindness, a loss of motor coordination and speech, 'insanity' and finally death[1,7].

Syphilis is easily detected with a blood test and if caught early can be easily treated with a short course of antibiotics (usually Penicillin)[1]. However, some instances of tertiary phase infection may not be treatable despite high-dose long-course antibiotic treatment[7]. Either way, the full course of treatment and follow-up testing must be taken to make sure an individual is clear of infection, and sexual contact should be avoided (even with normally 'effective' protection) until cured to prevent transmission, as male-to-female transmission occurs ≈20-30% per act of sexual intercourse[2,7].

Other Significant Bacterial STIs

Haemophilus ducreyi is species of bacteria responsible for the development of soft chancres (chancroids are swollen, painful ulcerations of genitalia and glands), which release infectious pus if burst[1]. Endemic in tropical areas, detection involves taking a swab of the chancroid, culturing of the bacteria and analysis. Treatment typically uses second- or third-generation Macrolide, Tetracycline and/or Cephalosporin antibiotics[1].

Klebsiella granulomatis produces granuloma inguinale (aka. donovanosis), an infection associated with leaky, large, raised painless ulcers which are commonly mistaken for syphilitic chancres[1]. While common in communities where antibiotics are rare (such as in developing countries and Aboriginal communities), the subsequent tissue destruction of ulcerated regions is easily detected and treated using second- or third-generation Macrolide, Tetracycline and/or Cephalosporin antibiotics[1].

References

1. Willey JM, Sherwood LM, Woolverton CJ. Prescott's Microbiology. 8th ed. Singapore: McGraw-Hill; 2011.
2. World Health Organization. Global incidence and prevalence of selected curable sexually transmitted infections – 2008 Geneva: World Health Organization, Department of Reproductive Health and Research; 2012. Available from: http://www.who.int/reproductivehealth/publications/rtis/stisestimates/en/index.html [Accessed 2014 Mar 24].
3. Department of Health (WA). Gonorrhoea Fact Sheet [Internet]. Perth, WA (Australia): Department of Health (WA); 2012 [cited 2014 Mar 26]. Available from: http://www.public.health.wa.gov.au/2/410/2/gonorrhoea_fact_sheet.pm.
4. Department of Health (WA). Quarterly Surveillance Report: Notifiable Sexually Transmissible Infections and Blood-borne Viruses in Western Australia - December 2013 [Internet]. Department of Health (WA) - Public Health and Clinical Services; 2014 Feb [cited 2014 Mar 26]. Report No.: 11(1). Available from: http://www.public.health.wa.gov.au/cproot/5693/3/stibbv_2013_4th_quarterly_report.doc.
5. Department of Health (WA). Chlamydia Fact Sheet [Internet]. Perth, WA (Australia): Department of Health (WA); 2013 [cited 2014 Mar 26]. Available from: http://www.public.health.wa.gov.au/2/406/2/chlamydia_fact_sheet.pm.
6. Department of Health (WA). Lymphogranuloma Venereum Fact Sheet [Internet]. Perth, WA (Australia): Department of Health (WA); 2008 [cited 2014 Mar 26]. Available from: http://www.public.health.wa.gov.au/2/794/2/lymphogranuloma_venereum_lgv.pm.
7. Department of Health (WA). Syphilis Fact Sheet [Internet]. Perth, WA (Australia): Department of Health (WA); 2011 [cited 2014 Mar 26]. Available from: http://www.public.health.wa.gov.au/2/416/2/syphilis.pm.