Ureaplasma urealyticum overview

# Overview
Ureaplasma species (U. urealyticum and U. parvum) are commensal organisms commonly found in the urogenital tract of sexually active men and women. These organisms are considered to be of low virulence although several studies have demonstrated an association between vaginal colonization by Ureaplasma species and adverse pregnancy outcomes including perinatal morbidity and mortality. Some studies also show an association between urogenital colonization by U. urealyticum and nongonococcal urethritis in men. However, the pathogenic role of Ureaplasma urealyticum in nongonococcal urethritis is still not clear. Colonization with Ureaplasma species occur in asymptomatic and symptomatic infants and adults, and further investigations to determine the exact pathogenic role of Ureaplasma is required. There is often a medical dilemma as to whether an isolation of Ureaplasma represents a 'true' infection or 'mere' colonization. Hence, the challenge in making a decision whether medical treatment is necessary.

# Historical Perspective
T-strain mycoplasma (now known as Ureaplasma urealyticum) was first discovered in the human urogenital tract in 1954 by Shepard et al. Tiny (T)-strain mycoplasma was renamed Ureaplasma urealyticum in 1974.

# Classification
U. urealyticum was previously classified into two biotypes:
- Biovar 1 ( parvo biovar): Ureaplasma urealyticum biovar 1 is now known as U. parvum.
- Biovar 2 (T960 biovar): Ureaplasma urealyticum biovar 2 strain retained its designation as U. urealyticum.

# Pathophysiology
Ureaplasma raises the pH of the vagina by hydrolyzing urea into carbon dioxide and ammonia, increasing the susceptibility to mixed infection with other pathogenic bacteria. These pathogens stimulate the secretion of pro-inflammatory cytokines and chemokines, leading to the recruitment of leukocytes and production of prostaglandins, which subsequently result in preterm birth. Vertical transmission of Ureaplasma has also been associated with neonatal complications such as pneumonitis, bacteremia, and meningitis, following stimulation of fetal inflammatory responses by the organism. Some studies conducted in men show there is an association between urogenital colonization by Ureaplasma urealyticum and nongonococcal urethritis, however, the pathogenic role of Ureaplasma urealyticum in nongonococcal urethritis is not clear.

# Causes
Ureaplasma species are bacteria belonging to the family Mycoplasmataceae.

# Differentiating Ureaplasma from other Bacteria
There are no specific signs and symptoms that can distinguish Ureaplasma infection from infection caused by other microorganisms. Ureaplasma species cannot be cultured on conventional culture media for most bacteria and special culture media for Mycoplasma is often needed.

# Epidemiology and Demographics
Ureaplasma species colonize 40-80% of the genital tract of healthy women.  They are the most common pathogen identified in VLBW infants. Ureaplasma colonization of the respiratory tract is more common in preterm VLBW infants compared to term infants. 20-45% of VLBW infants have Ureaplasma colonization of the respiratory tract.

# Risk factors
Several risk factors have been identified for Ureaplasma infection such as heavy urogenital colonization in adults, multiple sexual partners, immunosuppression, and prematurity in neonates.

# Natural History, Complications and Prognosis
The genital tract of adult men and women serve as the main reservoirs for Ureaplasma species. Pregnancy complications such as chorioamnionitis, preterm labor, and miscarriages have been associated with Ureaplasma. Neonatal complications associated with Ureaplasma include prematurity, pneumonia, pneumonitis, bronchopulmonary dysplasia, respiratory distress syndrome of the newborn and sepsis. Urogenital tract infections such as nongonococcal urethritis in men have also been associated with Ureaplasma urealyticum.

# History and Symptoms
It is important to take a history of the underlying risk factors for Ureaplasma colonization/infection. Nonspecific symptoms such as irritability, lethargy, convulsions and dyspnea can be seen in neonatal infection associated with Ureaplasma.

# Physical Examination
There is no physical examination finding that is specific or pathognomonic for Ureaplasma infection, and a laboratory diagnosis is required.

# Laboratory Findings
Ureaplasma species are diagnosed based on culture results and/or PCR.

# X ray
Early dysplastic pulmonary changes have been observed to occur more frequently in preterm infants with Ureaplasma colonization, although a previous study suggests there are no unique radiographic changes associated with Ureaplasma.

# CT
There are no specific CT findings associated with Ureaplasma colonization or infection.

# Other Diagnostic Studies
Microbial culture methods and/or PCR-based techniques are the only reliable methods for diagnosing Ureaplasma colonization/infection.

# Medical Therapy
Antibiotics are the mainstay of treatment for Ureaplasma infection, and antibiotic susceptibility testing is advised prior to treatment due to geographical differences in antibiotic resistance pattern. Doxycycline is recommended as the drug of first choice in non-pregnant women and adults. Josamycin is often recommended for neonates and pregnant women, especially when mixed infection is present. Clarithromycin and pristinamycin are also effective for treating Ureaplasma infection.

# Prevention
There are no guidelines for the prevention of Ureaplasma colonization or infection.