1	Univerzitetni klinični center Maribor, Ljubljanska 5,2000 Maribor, Slovenija
2	Inštitut za mikrobiologijo in imunologijo, Medicinska fakulteta v Ljubljani, Zaloška 4,1000 Ljubljana
3	Klinika za infekcijske bolezni in vročinska stanja, UKC Ljubljana, Japljeva ulica 2,1000 Ljubljana
Korespondenca/ Correspondence:
prof. dr. Mojca Matičič, dr. med., e: mojca.maticic@ kcLj.si
Ključne besede:
Ureaplasma parvum; Ureaplasma urealyticum; spolno prenosljive okužbe; diferencialna patogenost; ženske
Key words:
Ureaplasma parvum; Ureaplasma urealyticum; sexually transmitted infections; differential pathogenicity; females
Citirajte kot/Cite as:
Zdrav Vestn 2014; 83: 629-37
Prispelo: 18. nov. 2013, Sprejeto: 7. jul. 2014
Clinical role of Ureaplasma parvum and Ureaplasma urealyticum presence in female lower urogenital tract: Is there a place for routine screening and treatment?
KLinični pomen prisotnosti bakterij Ureaplasma parvum in Ureaplasma urealyticum v spodnjem urogenitaLnem traktu žensk: Je potrebno rutinsko presejanje in zdravljenje?
Maruška Marovt,1 Darja Keše,2 Jovan MiLjkovic,1 Mojca Matičič3
Abstract
Sexually transmitted infections represent major health problem in females all over the world if remained undiagnosed and untreated. They can have an adverse influence on the reproduction and health of the mother and the newborn. The development of molecular methods has permitted the detection of an array of microbes whose pathologic roles in urogenital infections need to be further studied. Ureaplasmas (Ureaplasma spp.), being originally found in 1954 from male urogenital tract, are prokaryotic cells without a cell wall, ranging from 0.1 to 1 ^m in length. Fourteen known Ureaplasma serovars, named also serotypes, have been divided in two species based on their phenotypic and genotypic features, Ureaplasma parvum and Ureaplasma urealyticum detected and identified separately using polymerase chain reaction assays. Both are generally considered as genital tract commensals. U. urealyticum is most probably associated with male urethritis which has not been found for U. parvum. Recent studies with supposedly healthy women reported their detection rate between 18-87 % for U. parvum and 6-10 % for U. urealyticum. Even though they have been found to be associated with chorioamnionitis, preterm birth and perinatal complications more commonly then other commensals in this region, the rising question regarding their pathogenic role in females remains unresolved and the guidelines regarding the diagnostic screening and treatment are inconsistent.
The aim of our paper is to review the microbiological characteristics, diagnostic methods and
epidemiology of newly differentiated U. parvum and U. urealyticum, and to assess evidence speaking for and against their clinical role in causing lower urogenital tract infection in women. Since both bacterial species are susceptible to antimicrobials, it is of utmost importance for clinicians to decide whether or not to search for one or both of them routinely and treat accordingly in order to prevent ascending upper genital tract infection as well as complications in pregnancy and newborns.
Izvleček
Spolno prenosljive okužbe žensk so velik jav-nozdravstveni problem povsod po svetu, če jih ne odkrijemo in ne zdravimo pravočasno. Ne-zdravljene lahko pomembno vplivajo na njihovo reproduktivno zdravje, zdravje nosečnic in novorojencev. Razvoj molekularnih diagnostičnih metod je omogočil odkritje številnih mikrobov, katerih klinični pomen pri ženskah z okužbo urogenitalnega trakta še ni pojasnjen. Ureaplaz-me ( Ureaplasma spp.) je prvi odkril Shepard leta 1954 pri moških v vzorcih urogenitalnega trakta. Ureaplazme so prokariotske celice brez celične stene, velike od 0,1 do 1 ^m. Na podlagi njihovih fenotipskih in genotipskih značilnosti ločimo štirinajst serovarjev, imenovanih tudi serotipi, ki so uvrščeni v dve ločeni vrsti, Ureaplasma parvum in Ureaplasma urealyticum. Posamezni vrsti dokazujemo z metodo verižne reakcije s polime-razo. Študije so pokazale povezavo med prisotnostjo U. urealyticum in uretritisom pri moških, medtem ko pri U. parvum te povezave ni bilo najti. Z nedavno opravljenimi raziskavami so v spodnjem urogenitalnem traktu domnevno zdravih
žensk dokazali U. parvum v 18-87 %, bakterijo U. urealyticum pa v 6-10 %. Kljub temu, da so raziskave pokazale povezavo med prisotnostjo ureaplazem in horioamnionitisom, prezgodnjim porodom in zapleti ob porodu pogosteje kot pri prisotnosti drugih komenzalov v tem področju, ostaja vprašanje o njihovi patogeni vlogi pri ženskah zaenkrat še nepojasnjeno. Prav tako pa ni
ustreznih smernic glede presejalnega testiranja in morebitnega zdravljenja teh okužb.
Namen prispevka je predstaviti mikrobiološke značilnosti, diagnostične metode in epidemiološke posebnosti novo diferenciranih bakterij U. parvum in U. urealyticum ter na temelju dosedanjih dognanj oceniti njihov morebitni klinični pomen pri okužbi spodnjega urogenitalnega trakta žensk.
1. Introduction
In 2008 WHO estimated that 449 million new cases of curable sexually transmitted infections (STIs) (syphilis, gonorrhoea, chlamydial infections and trichomoniasis) occur each year all over the world in adults aged 15-49 years.1 Females are severely and more commonly affected.2 Untreated STIs can have an adverse influence on the reproduction and health of the mother and the newborn and therefore represent an important preventable cause of infertility/ Unresolved cervicitis may lead to ascending infection, resulting in endometritis and salpingitis or ascending infection during pregnancy, resulting in chorioamnionitis, premature rupture of membranes, premature delivery, amniotic fluid infection, and puerperal infection.3 The development of molecular methods has permitted the detection of an array of microbes whose pathologic roles in urogenital infections need to be further studied, Ureaplasma spp. presenting the most interesting one.
Nowadays, evidence is accumulating that Ureaplasma urealyticum causes nongonococcal urethritis in males.4-8 Unlike U. urealyticum, Ureaplasma parvum does not seem to be associated with male urethritis. However, clinical role of U. parvum and U. urealyticum in lower urogenital tract infections in females is blurred, lacking larger epidemiological and clinical studies in women with urogenital symptoms and those without them. Since both bacterial species are susceptible to certain antimicrobials, guidelines are needed to clarify whether one or both of them should be sought for routinely and treat accordingly to prevent further complications in females.
The aim of our paper is to review the microbiological characteristics, diagnostic methods and epidemiology of newly differentiated U. parvum and U. urealyticum, and to assess evidence speaking for and against their clinical role in causing lower urogenital tract infection in women.
2. Microbiological characteristics of ureaplasmas
2.1. Classification
Ureaplasmas (Ureaplasma spp.) were originally found by Shepard in 1954 from male urogenital tract9 and the genus was established in 1974!°. Ureaplasma spp. is included within the class Mollicutes, which contains four orders, five families, eight genera, and more than 200 species that have been detected in humans, vertebrate animals, arthropods, and plants." Humans are the primary host for at least 17 species, primarily localized in the respiratory and urogenital tracts. Until 2002, U. urealyticum was considered to be the only species of this genus known to infect humans. By using polyclonal or monoclonal antibodies directed against whole cells or purified antigens, fourteen serovars (or serotypes) were recognized that were classified on the basis of 16S rRNA gene sequences into two biovars, biovar 1 and biovar 2. Biovars were later reclassified as two distinct species, U. parvum and U. ure-alyticum, based on genome size, 16S rRNA gene sequences, the 16S-23S rRNA interge-nic region, enzyme polymorphisms, DNA-DNA hybridization, differential growth
responses to manganese, and differences in the multiple banded antigen (mba) genes.12 Ureaplasma parvum now contains serotypes 1, 3, 6, and 14, while U. urealyticum includes the rest of 10 serotypes (2, 4, 5, 7, 8, 9, 10, 11, 12, and 13).
2.2.	Bacterial characteristics
Ureaplasmas are particularly small pro-karyotic cells without a cell wall, which makes them insensitive to the activity of beta--lactam antimicrobials, and precludes them from staining by Gram reaction." They are spherical or coccobacillary-shaped cells and have a diameter ranging from 0.1 to 1 ^m.12 Colonies produced by ureaplasmas are typically 15 to 60 ^m in diameter and require low-power microscopic magnification for visualization. 13 Ureaplasmas are the only prokaryotes that essentially need urea for their growth. Nearly all ATP synthesis results from urea hydrolysis/4 Ureaplasma parvum was the third sequenced mycopla-sma, and has the smallest sequenced genome among prokaryotes except Mycoplasma genitalium. It includes the serotypes with smaller genome (0.75-0.76 megabase pairs, Mbp), whereas U. urealyticum includes 10 serotypes with larger genome (0.88-1.2 Mbp).
2.3.	Virulence factors
Attachment to host cell surfaces is essential for ureaplasmas to colonize and afterwards produce pathological changes. Factors involved with their attachment to mucosal surfaces have so far not been extensively studied, but they are known to adhere to erythrocytes!5, spermatozoa^, urethral epithelial cells!7, and neutrophils.!8
Five proteins such as urease, immunoglobulin-a (IgA) protease, pho-spholipases A and C, and multiple banded antigen (MBA), along with the ureaplasma enzymes for producing hydrogen peroxide have been suggested as virulence factors.14
Genes involved in pathogenicity have not been conclusively identified. Xiao and colleagues have recently shown that individual serovars are not likely to be associated with differential pathogenicity/9
3. Diagnostic methods for ureaplasmas
Methods for laboratory detection of ure-aplasmas have been greatly improved over the past years because of effective molecular-based techniques. Relatively rapid bacterial growth makes the identification of most positive cultures possible within two to four days, but culture cannot differentiate between the two species.13
Molecular-based methods, such as PCR, are able to detect and identify U. parvum and U. urealyticum separately. For target sequences, 16S rRNA gene, 16S rRNA to 23S rRNA intergenic spacer regions, the urease gene, and mba gene are mainly used/0 In addition, a number of diverse genotyping methods have been developed for identification of Ureaplasma serotypes: restriction fragment length polymorphism (RFLP), pulsed-field gel electrophoresis (PFGE), a high-resolution melt (HRM) PCR assay, real-time PCR, and multilocus sequence typing (MLST) assay/i^ In 2010 Xiao and colleagues showed originally that all 14 serotype strains of ureaplasmas can be distinctly differentiated from one another by using real-time PCR technology/3 Polymerase chain reaction seems to be more sensitive for diagnostic purposes compared to culture; among 132 clinical specimens, PCR detected 20 (15.2 %) positive samples more compared to culture.23 Advantages of molecular-based methods compared to culture and serologi-cal analysis for the detection of ureaplasmas and mycoplasmas are discussed in detail by Waites and colleagues/0
While using PCR as the gold standard, first-voided urine specimens from women were reported having the lowest overall sensitivity (84.6 °%) when compared to endo-cervical swab (98.1 %) and the sensitivity of self-collected vaginal specimens (99.3 %).24
Culture remains the most economical and practical means of detection for laboratories with a low to moderate sample volume. Culture also has an advantage of providing antimicrobial susceptibility testing.20 Whether culture- or non-culture-based detection methods should be used for diagnostic purposes depends on the resources and
5. Clinical role of ureaplasmas in females
5.1. Infection of the lower urogenital tract
Both U. parvum and U. urealyticum are generally considered as female urogenital tract commensals. Even though they are more commonly than other normal flora in the urogenital region associated with some clinical syndromes such as chorioamnio-nitis and preterm birth as well as perinatal morbidity and mortality, the rising question regarding their pathogenic role in females remains unresolved.30 Recent study in 303 presumably healthy women from Japan attending their first prenatal visit has shown that there was a significant association between urogenital presence of Chlamydia trachomatis and either U. parvum (p = 0.023) or Ureaplasma spp. (p = 0.013), but not U. urealyticum (p = 0.275).3o This finding suggests that ureaplasmas might change the urogenital microenvironment and enable the survival of C. trachomatis. However, data on the mutual effect of urogenital flora is limited.
5.1.1. Symptomatic Lower urogenital, tract infection in ureapLasma-positive femaLes
Using culture, Schlicht and colleagues (2004) found out Ureaplasma spp. in 21/39 (54 %) of symptomatic and only in 4/25 (16 %) of asymptomatic women, the difference being significant.33 However, the number of asymptomatic females was low. In 2009, De Francesco reported that U. parvum sero-var 3 and U. urealyticum were significantly associated with symptomatic women compared to asymptomatic ones (p < 0.05)/4
Table 1: Prevalence of Ureaplasma parvum and Ureaplasma urealyticum in supposedly healthy female population.
Author	Country	N	U. parvum	U. urealyticum
Mciver, 20 0927	Australia	233	57 %	6.1 %
Kong, 200028	Australia	263	87 %	19 %
Kataoka, 20 0629	Japan	877	52 %	8.7 %
Yamazaki, 201230	Japan	303	41.7 %	8.9 %
Cao, 200731	China	128	53.1 %	7.8 %
Ekiel, 20 0932	Poland	39	17.9 %	2.6 %
facilities available in individual laboratories and the species being sought.20
Indirect, serological test methods for ureaplasmas include microimmunofluore-scence, metabolism inhibition, and enzyme immunoassay13, but the interpretation of antibody titers is difficult because of their ubiquity in healthy people so it is of limited clinical use.20
4. Epidemiology of ureaplasmas
Ureaplasmas can be detected in the cervix or vagina of 40 to 80 % of sexually mature asymptomatic women/5 Colonization is more common in females of younger age, lower socioeconomic status, with multiple sex partners, black ethnicity, and those using oral contraceptives. Incidence of ureaplasmas in female genital tract is most probably dependent on hormonal status; incidences in the prepuberty, puerperium, postmenopause, in pregnant women, in sexually inactive women, and in sexually active nonpregnant women were 5 %o, 24 %o, 25 %, 82 %, 40 %, and 67 %, respectively/6
Studies with supposedly healthy women reported Ureaplasma spp. detection rate at approximately 18-87 0% for U. parvum and 6-10 % for U. urealyticum (Table 1).
In this study only the samples with isolated ureaplasmas and no other bacteria were evaluated. U. parvum was found in 64/80 (80 %) of symptomatic compared to 56/59 (95 %) of asymptomatic women whereas U. urealyti-cum was found in 16/80 (20 %) of symptomatic compared to 3/59 (5 %) of asymptomatic women. U. parvum serovar 3 was present most commonly in the 21 to 25-year-old age group, while U. urealyticum was distributed with quite similar frequency in women of 26 to 30 and > 40 years of age. U. parvum sero-var 3 and U. urealyticum were found to be significantly associated with loss of lactoba-cilli, while U. parvum serovar 6 was significantly correlated to normal vaginal flora. In a study by McKechnie and colleagues in 2011, U. parvum was found in 51/111 (45.9 %) of symptomatic compared to 52/105 (49.5 %) of asymptomatic women and U. urealyticum was found in 30/111 (27 %) of symptomatic compared to 23/105 (21.9 %) of asymptomatic women.24 Researchers did not find any significant differences in detection rates when comparing symptomatic and asymptomatic women neither for U. parvum nor for U. urealyticum. Women were classified as cases when reporting one or more of the following symptoms: vaginal discharge, irritation, dysuria, urinary frequency or pelvic pain, and as controls when presenting with none of these specific symptoms. In 2013, Hunjak and colleagues isolated ureaplasmas from cervicovaginal or urethral swab in 34.4 % of 1370 women visiting gynecological practice (28.5 % being pregnant).35 Out of 244 samples 18 (7.4 %) were identified as U. urealyticum and 226 (92.6 %) as U. parvum, 15/18 U. urealyticum cases (83.3 %) being isolated in symptomatic and 3/18 (16.7 %) in asymptomatic women, while 179/226 (79.2 %) and 47/226 (20.8 %) of U. parvum cases were isolated in symptomatic and asymptomatic women, respectively. There were no statistically significant differences in the incidence of either U. urealyticum or U. parvum regarding the presence of symptoms or pregnancy.
Studies on the association between ure-aplasmas and cervicitis in particular are sparse. In 1985 research by Paavonen and colleagues, Ureaplasma spp. was the only
organism significantly associated with mu-copurulent cervicitis after adjustment for the results of cervical culture for C. trachomatis.36 No other studies on the matter have been found so far.
In several studies ureaplasmas have been shown to be associated with bacterial vaginosis (BV)/7 However, studies regarding the association between newly differentiated ureaplasmas and BV are sparse. In women who delivered preterm, U. ure-alyticum was detected significantly more often in specimens from those with clinical diagnosis of BV (3/7), compared to those without it (2/42) (OR 15.95 % CI 1.2-209) as was shown by Povlsen and colleagues in 2001.38 The group of women with BV who delivered preterm was limited. There was no difference in the proportion of biovar strains when comparing women who delivered preterm and women who delivered at term. U. urealyticum was present more frequently in women with BV (57/70) compared to women without it (223/414) (OR 3-7, 95 % CI 2.0-7.0). In 2008 Haggerty and colleagues defined BV by Amsel's and Nugent's criteria and detected them both more frequently among women who were positive for U. ure-alyticum, compared to women who were U. urealyticum negative (57 % vs. 50 % and 64 % vs. 53 %, respectively), however, the differences were small and did not reach statistical significance.39
5.2. Infection in pregnancy and neonates
Possible association between ureapla-smas and adverse pregnancy outcome is a topic of great interest and has not been resolved satisfactorily. Studies that were limited to sampling the lower genital tract of women have yielded inconclusive results, mainly because not all women who are colonized in the lower tract will develop infection in the upper tract.11 Occurrence of ureaplasmas in pregnant women provides a reservoir for transmission to the fetus and neonate/0 It can occur as an ascending intrauterine infection, through a hematogenous route or acquisition by the neonate through passage of an infected maternal birth canal.n
The most conclusive data associating adverse pregnancy outcomes with ureapla-smas were obtained from prospective studies in which ureaplasmas were detected in the amniotic fluid.41-43 Ureaplasma spp. are most frequently isolated from the amnio-tic fluid or placenta in women who deliver prematurely, either with preterm premature rupture of membranes or in preterm labor with intact membranes, and isolation of Ureaplasma spp. has been consistently associated with histological chorioamnionitis."
There is significant association and/or strong suggestive evidence without proven causal role between Ureaplasma spp. and congenital pneumonia as well as neonatal bacteremia, neonatal meningitis and neonatal abscesses.40
6. Treatment of ureaplasma infection
Mollicutes are innately resistant to all beta-lactams, sulfonamides, trimethoprim, and rifampin. Ureaplasma spp. is susceptible to erythromycin and other 14- and 15-mem-bered macrolides but resistant to clinda-mycin.13 Tetracycline resistance has been well documented in Ureaplasma spp. since the mid-eighties, mediated by the tet(M) determinant which codes for a protein that binds to the ribosomes, protecting them from the actions of these drugs." The extent to which tetracycline resistance occurs in Ureaplasma spp. varies geographically and according to prior exposure in different populations but may approach 40 do 50 %." High-level macrolide-resistant U. parvum was recently reported from the United King-dom44, but such resistance is believed to be rare.13 Fluoroquinolones such as the latest levofloxacin and moxifloxacin are usually active against all human mycoplasmal and ureaplasmal species." Infrequent fluoroqui-nolone-resistant strains of Ureaplasma spp. have first been reported from China, France and the USA/5^6 However, in a 2013 study from Croatia, all of the 424 ureaplasma strains were susceptible to doxycycline, tetra-cycline, erythromycin and clarithromycin, whereas the susceptibilities to ofloxacin and
ciprofloxacin were 42.9 % and 24.5 %, respectively^
7. Future implications for clinicians
Because several investigators have proposed an association between certain urea-plasma serotypes and certain diseases, and others were not able to affirm that association, an association between ureaplasmas and clinically important infection should probably be understood in terms of biovars (now newly recognized species) rather than serotypes.47 Studies have shown that some strains are more firmly associated with the disease. However, more studies are needed to find out whether this is due to either bacterial virulence factors, host response, local environment or their combination. Information gained from animal models48'4® and hu-mans50'5i suggests that intact host response is essential in overcoming the disease.
Presuming that non-specific cervicitis represents an analog of male non-gonoco-ccal urethritis, can we assume that in females U. urealyticum is more pathogenic than U. parvum? Or: are certain U. parvum se-rovars in females clinically more important than others? Is there a difference between males and females regarding ureaplasmas? Since infection of the female lower urogenital tract can lead to ascending upper genital tract infection and causes complications in the infected women, pregnancy as well as in the newborn, it is of essential importance to recognize all clinically important pathogens and treat the condition accordingly. Considering the low cost of sequencing nowadays, the genomes of ureaplasma isolates from women with different clinical conditions, including those who deliver prematurely, should be sequenced routinely/2 The comparison of sequences should further aid the identification of genes involved in differential pathogenicity.
Since both bacteria are susceptible to macrolides, tetracyclines and the latest fluo-roquinolones, consistent guidelines should be available to clinicians enabling them to decide whether or not to search for one or
both bacteria including their serotypes routinely and treat the condition accordingly, regardless the presence or absence of symptoms to prevent complications. Clinicians should be aware of the possibility in expanding diagnostic means in view of better clinical management of females.
References
1.	WHO. Sexually transmitted infections. World Health Organization 2013; Available November 15, 2013 from: http://www.who.int/mediacentre/ factsheets/fsiio/en/.
2.	Buve A, Gourbin C, Laga M. Gender and sexually transmitted diseses. In: Holmes KK, Sparling PF, Stamm WE, Piot P, Wasserheit JN, Corey L, et al, eds. Sexually transmitted diseases. 4th ed. New York: McGraw-Hill; 2008. p. 151-64.
3.	Holmes KK, Stamm WE, Sobel JD. Lower genital tract infection syndromes in women. In: Holmes KK, Sparling PF, Stamm WE, Piot P, Wasserheit JN, Corey L, et al, eds. Sexually transmitted diseases. 4th ed. New York: McGraw-Hill; 2008. p. 987-1016.
4.	Povlsen K, Bjornelius E, Lidbrink P, Lind I. Relationship of Ureaplasma urealyticum biovar 2 to nongonococcal urethritis. Eur J Clin Microbiol Infect Dis 2002; 21: 97-101.
5.	Deguchi T, Yoshida T, Miyazawa T, Yasuda M, Ta-maki M, Ishiko H, et al. Association of Ureaplasma urealyticum (biovar 2) with nongonococcal urethritis. Sex Transm Dis 2004; 31: 192-5.
6.	Couldwell DL, Gidding HF, Freedman EV, McKe-chnie ML, Biggs K, Sintchenko V, et al. Ureaplasma urealyticum is significantly associated with non-gonococcal urethritis in heterosexual Sydney men. Int J STD AIDS 2010; 21: 337-41.
7.	Ondondo RO, Whittington WL, Astete SG, Totten PA. Differential association of ureaplasma species with non-gonococcal urethritis in heterosexual men. Sex Transm Infect 2010; 86: 271-5.
8.	Maeda S, Deguchi T, Ishiko H, Matsumoto T, Na-ito S, Kumon H, et al. Detection of Mycoplasma genitalium, Mycoplasma hominis, Ureaplasma parvum (biovar 1) and Ureaplasma urealyticum (biovar 2) in patients with non-gonococcal ure-thritis using polymerase chain reaction-microtiter plate hybridization. Int J Urol 2004; 11: 750-4.
9.	Shepard MC. The recovery of pleuropneumonia--like organisms from Negro men with and without nongonococcal urethritis. Am J Syph Gonorrhea Vener Dis 1954; 38: 113-24.
10.	Shepard MC, Lunceford CD, Ford DK, Purcell RH, Taylor-Robinson D, Razin S, et al. Ureapla-sma urealyticum gen. nov. sp. nov.: proposed nomenclature for the human T (T-strain) mycoplasmas. Int J Syst Bacteriol 1974; 24: 160-71.
8. Conclusion
Limited number of studies investigating the clinical role of presence of U. parvum and U. urealyticum as well as some of their serovars in the female lower urogenital tract gave no conclusive results. Future studies are warranted. So far, clinicians should be aware of the possibility in expanding diagnostic means in view of better clinical management of their female patients.
11.	Waites KB, Katz B, Schelonka RL. Mycoplasmas and ureaplasmas as neonatal pathogens. Clin Microbiol Rev 2005; 18: 757-89.
12.	Robertson JA, Stemke GW, Davis JW, Jr., Harasa-wa R, Thirkell D, Kong F, et al. Proposal of Ureaplasma parvum sp. nov. and emended description of Ureaplasma urealyticum (Shepard et al. 1974) Robertson et al. 2001. Int J Syst Evol Microbiol
2002; 52: 587-97.
13.	Waites KB, Taylor-Robinson D. Mycoplasma and Ureaplasma. In: Versalovic J, ed. Manual of Clinical Microbiology. 10th ed. Washington DC: ASM Press; 2011. p. 970-85.
14.	Glass JI, Lefkowitz EJ, Glass JS, Heiner CR, Chen EY, Cassell GH. The complete sequence of the mucosal pathogen Ureaplasma urealyticum. Nature
2000; 407: 757-62.
15.	Saada AB, Terespolski Y, Adoni A, Kahane I. Adherence of Ureaplasma urealyticum to human erythrocytes. Infect Immun 1991; 59: 467-9.
16.	Busolo F, Zanchetta R, Bertoloni G. Mycoplasmic localization patterns on spermatozoa from infertile men. Fertil Steril 1984; 42: 412-7.
17.	Shepard MC, Masover GK. Special features of ureaplasmas. In: Barile MF, Razin S, eds. The myco-plasmas, vol 1. New York, N. Y.: Academic Press;
1979. p. 451-94.
18.	Taylor-Robinson D, Furr PM, Webster AD. Urea-plasma urealyticum in the immunocompromised host. Pediatr Infect Dis 1986; 5(Suppl 6): S236-8.
19.	Xiao L, Paralanov V, Glass JI, Duffy LB, Robertson JA, Cassell GH, et al. Extensive horizontal gene transfer in ureaplasmas from humans questions the utility of serotyping for diagnostic purposes. J Clin Microbiol 2011; 49: 2818-26.
20.	Waites KB, Xiao L, Paralanov V, Viscardi RM, Glass JI. Molecular methods for the detection of Mycoplasma and ureaplasma infections in humans: a paper from the 2011 William Beaumont Hospital Symposium on molecular pathology. J Mol Diagn 2012; 14: 437-50.
21.	Payne MS, Tabone T, Kemp MW, Keelan JA, Spiller OB, Newnham JP. High-resolution melt PCR analysis for genotyping of Ureaplasma parvum isolates directly from clinical samples. J Clin Micro-biol 2014; 52: 599-606.
22.	Zhang J, Kong Y, Feng Y, Huang J, Song T, Ruan Z, et al. Development of a multilocus sequence typing scheme for Ureaplasma. J Clin Microbiol Infect Dis 2014; 33: 537-44.
23.	Xiao L, Glass JI, Paralanov V, Yooseph S, Cassell GH, Duffy LB, et al. Detection and characterization of human Ureaplasma species and serovars by real-time PCR. J Clin Microbiol 2010; 48: 2715-23.
24.	McKechnie ML, Hillman RJ, Jones R, Lowe PC, Couldwell DL, Davies SC, et al. The prevalence of urogenital micro-organisms detected by a multiplex PCR-reverse line blot assay in women attending three sexual health clinics in Sydney, Australia. J Med Microbiol 2011; 60: 1010-6.
25.	Cassell GH, Waites KB, Watson HL, Crouse DT, Harasawa R. Ureaplasma urealyticum intrauterine infection: role in prematurity and disease in newborns. Clin Microbiol Rev 1993; 6: 69-87.
26.	Iwasaka T, Wada T, Kidera Y, Sugimori H. Hormonal status and mycoplasma colonization in the female genital tract. Obstet Gynecol 1986; 68: 263-6.
27.	Mclver CJ, Rismanto N, Smith C, Naing ZW, Rayner B, Lusk MJ, et al. Multiplex PCR testing detection of higher-than-expected rates of cervical mycoplasma, ureaplasma, and trichomonas and viral agent infections in sexually active australian women. J Clin Microbiol 2009; 47: 1358-63.
28.	Kong F, Ma Z, James G, Gordon S, Gilbert GL. Species identification and subtyping of Ureaplasma parvum and Ureaplasma urealyticum using PCR-based assays. J Clin Microbiol 2000; 38:
1175-9.
29.	Kataoka S, Yamada T, Chou K, Nishida R, Mori-kawa M, Minami M, et al. Association between preterm birth and vaginal colonization by mycoplasmas in early pregnancy. J Clin Microbiol 2006;
44: 51-5.
30.	Yamazaki T, Matsumoto M, Matsuo J, Abe K, Minami K, Yamaguchi H. Frequency of Chlamydia trachomatis in Ureaplasma-positive healthy women attending their first prenatal visit in a community hospital in Sapporo, Japan. BMC Infect Dis 2012; 12: 82.
31.	Cao X, Wang Y, Hu X, Qing H, Wang H. Real-time TaqMan polymerase chain reaction assays for quantitative detection and differentiation of Ureaplasma urealyticum and Ureaplasma parvum. Di-agn Microbiol Infect Dis 2007; 57: 373-8.
32.	Ekiel AM, Friedek DA, Romanik MK, Jozwiak J, Martirosian G. Occurrence of Ureaplasma parvum and Ureaplasma urealyticum in women with cervical dysplasia in Katowice, Poland. J Korean Med Sci 2009; 24: 1177-81.
33.	Schlicht MJ, Lovrich SD, Sartin JS, Karpinsky P, Callister SM, Agger WA. High prevalence of genital mycoplasmas among sexually active young adults with urethritis or cervicitis symptoms in La Crosse, Wisconsin. J Clin Microbiol 2004; 42: 4636-40.
34.	De Francesco MA, Negrini R, Pinsi G, Peroni L, Manca N. Detection of Ureaplasma biovars and polymerase chain reaction-based subtyping of Ureaplasma parvum in women with or without symptoms of genital infections. Eur J Clin Micro-biol Infect Dis 2009; 28: 641-6.
35.	Hunjak B, Sabol I, Vojnovic G, Fistonic I, Erceg AB, Persic Z, et al. Ureaplasma urealyticum and Ureaplasma parvum in women of reproductive age. Arch Gynecol Obstet 2013 (in press). Available August 4, 2013 from: http://link.springer.com/ article/10.1007/s00404-013-2980-z.
36.	Paavonen J, Critchlow CW, DeRouen T, Stevens CE, Kiviat N, Brunham RC, et al. Etiology of cervical inflammation. Am J Obstet Gynecol 1986;
154: 556-64.
37.	Totten PA, Taylor-Robinson D, Jensen JS. Genital Mycoplasmas. In: Holmes KK, Sparling PF, Stamm WE, Piot P, Wasserheit JN, Corey L, et al, eds. Sexually transmitted diseases. 4th ed. New York: McGraw-Hill; 2008. p. 709-36.
38.	Povlsen K, Thorsen P, Lind I. Relationship of Ure-aplasma urealyticum biovars to the presence or absence of bacterial vaginosis in pregnant women and to the time of delivery. Eur J Clin Microbiol Infect Dis 2001; 20: 65-7.
39.	Haggerty CL, Totten PA, Ferris M, Martin DH, Hoferka S, Astete SG, et al. Clinical characteristics of bacterial vaginosis among women testing positive for fastidious bacteria. Sex Transm Infect 2009; 85: 242-8.
40.	Waites KB, Schelonka RL, Xiao L, Grigsby PL, Novy MJ. Congenital and opportunistic infections: Ureaplasma species and Mycoplasma homi-nis. Semin Fetal Neonatal Med 2009; 14: 190-9.
41.	Gray DJ, Robinson HB, Malone J, Thomson RB, Jr. Adverse outcome in pregnancy following amnio-tic fluid isolation of Ureaplasma urealyticum. Pre-nat Diagn 1992; 12: 111-7.
42.	Horowitz S, Mazor M, Romero R, Horowitz J, Gle-zerman M. Infection of the amniotic cavity with Ureaplasma urealyticum in the midtrimester of pregnancy. J Reprod Med 1995; 40: 375-9.
43.	Gardella C, Riley DE, Hitti J, Agnew K, Krieger JN, Eschenbach D. Identification and sequencing of bacterial rDNAs in culture-negative amniotic fluid from women in premature labor. Am J Peri-natol 2004; 21: 319-23.
44.	Beeton ML, Chalker VJ, Maxwell NC, Kotecha S, Spiller OB. Concurrent titration and determination of antibiotic resistance in ureaplasma species with identification of novel point mutations in genes associated with resistance. Antimicrob Agents Chemother 2009; 53: 2020-7.
45.	Bebear CM, Renaudin H, Charron A, Clerc M, Pe-reyre S, Bebear C. DNA gyrase and topoisomerase IV mutations in clinical isolates of Ureaplasma spp. and Mycoplasma hominis resistant to fluoro-quinolones. Antimicrob Agents Chemother 2003; 47: 3323-5.
46.	Duffy L, Glass J, Hall G, Avery R, Rackley R, Peterson S, et al. Fluoroquinolone resistance in Ureaplasma parvum in the United States. J Clin Micro-biol 2006; 44: 1590-1.
47.	Povlsen K, Jensen JS, Lind I. Detection of Ureapla-sma urealyticum by PCR and biovar determination by liquid hybridization. J Clin Microbiol 1998; 36: 3211-6.
48.	Reyes L, Reinhard M, Brown MB. Different inflammatory responses are associated with Ureaplasma parvum-induced UTI and urolith formation. BMC Infect Dis 2009; 9: 9.
49.	von Chamier M, Allam A, Brown MB, Reinhard MK, Reyes L. Host genetic background impacts disease outcome during intrauterine infection with Ureaplasma parvum. PloS One 2012; 7:
e44047.
50.	Spelman DW, Bradford D. Intraurethral immuno- 52. Paralanov V, Lu J, Duffy LB, Crabb DM, Shriva-globulin in the treatment of non-specific urethri-	stava S, Methe BA, et al. Comparative genome tis. Br J Vener Dis 1984; 60: 58-9.	analysis of 19 Ureaplasma urealyticum and Urea-
51.	Taylor-Robinson D, Furr PM, Webster AD. Ure-	plasma parvum strains. BMC Microbiol 2012; 12: aplasma urealyticum causing persistent urethritis	88.
in a patient with hypogammaglobulinemia. Ge-nitourin Med 1985; 61: 404-8.