Mycoplazma genitalium

Mycoplasma genitalium is a small parasitic bacterium which lives on the ciliated epithelial cells of the primate genital and respiratory tracts. M. genitalium is the smallest known free-living bacterium, and the second-smallest bacterium after the recently-discovered endosymbiont Carsonella ruddii. Until the discovery of Nanoarchaeum in 2002, M. genitalium was also considered to be the organism with the smallest genome.

 

Overview

Mycoplasma genitalium was originally isolated in 1980 from urethral specimens of two male patients with non-gonococcal urethritis. Infection by M. genitalium seems fairly common, can be transmitted between partners during unprotected sexual intercourse, and can be treated with antibiotics; however, the organism's role in genital diseases is still unclear.

The genome of M. genitalium consists of 521 genes (482 protein encoding genes) in one circular chromosome of 582,970 base pairs. An initial study of the M. genitalium genome with random sequencing was performed by Peterson in 1993. It was then sequenced by Fraser and others. It was found to contain only 470 predicted coding regions, including genes required for DNA replication, transcription and translation, DNA repair, cellular transport, and energy metabolism. It was the second complete bacterial genome ever sequenced, after Haemophilus influenzae. The small genome of M. genitalium made it the organism of choice in The Minimal Genome Project, a study to find the smallest set of genetic material necessary to sustain life.

Symptoms

Various symptoms of infection: an infected person may have some or all symptoms, or may be asymptomatic.

• Urethritis (in men)
• Discharge (both sexes)
• Burning while urinating (both sexes)
• Arthritis/reactive arthritis (mostly men)
• Vaginal itching
• Pain during intercourse (women)
• This infection is associated with bacterial vaginosis
• In the long term, this infection is suspected to cause pelvic inflammatory disease

Treatment

The CDC recommends using one of these treatments, in this order of prevalence (the first is known to be the most effective, the others are alternative treatments)

• Azithromycin 1 g orally in a single dose
• Doxycycline 100 mg orally twice a day for 7 days
• Erythromycin base 500 mg orally four times a day for 7 days
• Erythromycin ethylsuccinate 800 mg orally four times a day for 7 days
• Ofloxacin 300 mg orally twice a day for 7 days
• Levofloxacin 500 mg orally once daily for 7 days

However, this study Azithromycin Failure in Mycoplasma genitalium Urethritis says that "...doxycycline and levofloxacin have substantial failure rates..." and "...Recurrent urethral symptoms following azithromycin therapy only occurred in persons with persistent M. genitalium infection and resolved with moxifloxacin."

So moxifloxacin appears to be an alternative treatment after one of the other treatments have already failed (Azithromycin 1g is the preferred first line treatment).

Synthetic life

In October 2007, a team of scientists headed by DNA researcher Craig Venter and Nobel laureate Hamilton Smith announced that they plan to create the first artificial life form in history by creating a synthetic chromosome which they plan to inject into the M. genitalium bacterium, potentially resulting in an artificial species dubbed Mycoplasma laboratorium or Mycoplasma JCVI-1.0 after the research centre in which it was created, the J. Craig Venter Institute in the United States.

On 24 January 2008, the same team reported to have synthesized the complete 582,970 base pair genome of M. genitalium (a key gene that enables the wild organism to cause disease was knocked out). The final stage of synthesis was completed inside a M capricolum which had its DNA removed, with the help of yeast cells. On 20 May 2010 they reported success with a similar process, using instead the genome of Mycoplasma mycoides, creating what some called the first artificial life.

See also

• The Minimal Genome Project
• Candidatus Carsonella ruddii
• Arthritis / Reactive arthritis / Septic arthritis

External links

• Mycoplasma genitalium Reference Work at the UK Health Protection Agency
• Mycoplasma genitalium G-37 genome page