Ureaplasma urealyticum is a bacterium belonging to the genusUreaplasma and class Mollicutes. The Mycoplasmatota family consists of the genera Mycoplasma and Ureaplasma. Its type strain is T960. These strains of bacteria are commonly found as commensals in the urogenital tracts of human beings. Unlike most bacteria, Ureaplasma urealyticum lacks a cell wall making it unique in physiology and medical treatment.[1]
Additionally, it hydrolyzes urea as part of its energy metabolism processes. Its potential pathogenicity is being evaluated regarding urogenital, pregnancy, and neonatal conditions, however the clinical significance of detecting U. urealyticum remains uncertain for many conditions due to its asymptomatic tendencies.[2] Colonization is common and detection does not equate to disease.
Classification
Ureaplasma urealyticum is one of two Ureaplasma species commonly idenified within humans.[3] A defining characteristic of the genus is that they perform ureahydrolysis, which creates ammonia as a product. Some strains that were originally classified as U. urealyticum are now classified as a new species, U. parvum.[4]
U. urealyticum had 14 recognized serovar strains found in humans that uniquely express human immunoglobulin A1 protease activity. These serovars were grouped into two clusters, the parvo biovar and the T960T biovar, due to different characteristics. Genotypic markers of the biovars were differing genome sizes as well as 60% DNA-DNA hybridization. PCRs, based on the divergent nucleotide sequences of the two biovars, made it possible to differentiate the biovars reliably.[5]
Due to the accurate and accessible tests for biovar differentiation, researchers proposed an update to U. urealyticum taxonomic status. Serovar strains from the parvo biovar (serovars 1,3,6 and 14), are now designated as Ureaplasma parvum as well as strain 27T. Serovar strains from biovar T960T (2, 4, 5, 7 - 13) retain the U. urealyticum designation and type strain.[5]
Microbiology
Gram staining
U. urealyticum represents one of the 14 distinct types within the Ureaplasma genus. Classified within the Mollicutes class, Ureaplasma species have undergone significant evolutionary adaptations from their Gram-positive bacterial ancestors, a phenomenon termed degenerative evolutions (Kallapur, Suhas G, et al 2013[6]). This evolutionary trajectory has resulted in the loss of the peptidoglycan cell wall, a hallmark characteristic of Gram-positive and Gram-negative bacteria. Due to this evolutionary divergence, it is imperative to recognize that the U. urealyticum does not prove to be reactive with Gram staining. Because Gram staining depends on differences in cell-wall structure, Ureaplasma cannot be characterized as Gram-positive or Gram-negative by conventional Gram staining. The absence of a cell wall has clinical significance because antibiotics that inhibit cell wall synthesis are not effective in treating this bacteria.[7]
ATP Synthesis
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Clinical relevance
Ureaplasma urealyticum can cause urethritis and may cause bacterial vaginosis. Infection can occur in extragenital sites.[4] A common symptom associated with these infections is the "fishy" smell that is created due to the production of ammonia by the hydrolysis of urea. Patients should confirm diagnosis with a doctor. The bacterium has high correlations with the Human Papillomavirus (HPV).[medical citation needed] It has also been linked to infertility in both males and females.[medical citation needed] However, in males, there has been mixed results due to other studies finding that the sperm concentration, motility, and morphology were similar in groups that were positive and negative for Ureaplasma urealyticum though the positive group having a significantly higher count of anti-sperm antibodies.[8]
Pregnancy and neonatal outcomes
In addition, this pathogen may latently infect the chorionic villi tissues of pregnant women, thereby impacting pregnancy outcome.[medical citation needed] Issues that arise from Ureaplasma urealyticum infections during pregnancy include preterm birth and impacted embryonic development.[medical citation needed] Some patients have given birth to children subjected to bronchopulmonary dysplasia, Intraventricular hemorrhage, and necrotizing enterocolitis.[7] In a study done in 2024 it found increased odds in bronchopulmonary dysplasia, and Intraventricular hemorrhage but found the correlation in necrotizing enterocolitis was not significant[9] However, in another study it found that the genus of Ureaplasma causes higher odds of necrotizing enterocolitis in very low birth weight (VLBW) infants.[10] Many of these findings are associations as there are other confounding variables such as gestational age or birth weight. Patients can evolve resistances to normal antibiotic treatments due to the distinctive physiology of these organisms. In the Western World, approximately 40% of Ureaplasma species are resistant to fluoroquinolones (i.e. ciprofloxacin).[11] Patients who are pregnant have further limitations on the treatment course of a Ureaplasma urealyticum infection, making it far harder to successfully cure.[citation needed]
Treatment
Because Ureaplasma urealyticum lacks a cell wall, it is resistant to β-lactam antibiotics including cephalosporins and penicillins, which are commonly used to treat urinary tract infections.[12] The Ureaplasma species can colonize the human urogenital tract without producing symptoms making it difficult to detect and determine an active infection.[13]
Common antibiotics used to treat U. urealyticum include fluoroquinolones, tetracyclines and macrolides because they target DNA replication or protein synthesis rather than the cell wall, which the bacterium lacks.[12] However, certain strains of the Ureaplasma species have been reported to be resistant towards fluoroquinolones, tetracyclines and macrolides making treatment options limited.[14] Treatment can be difficult due to the bacterium’s ability to develop genetic mutations which contributes to antibiotic resistance. These mutations may alter the antibiotic target sites reducing the effectiveness of treatments.[12]
However, there are new movements to use azithromycin, a macrolide, to treat these infections. When Azithromycin is ingested, macrophages take it up and deliver it to the sites of infection.[14]) This helps control the infection where the bacteria grows. Additionally, it is also a great alternative to when a pregnant woman is infected to prevent harm to the fetus, as this antibiotic is transported and acts locally.[citation needed]
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