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Infrequently, post-Caesarean endometritis can progress to severe conditions. A case of post-Caesarean endometritis caused by Mycoplasma hominis and Ureaplasma urealyticum is reported in a young patient. In therapy-resistant endometritis unusual causative organisms should be considered and special microbiological investigations are recommended.

Three serovars (5, 8 and 10) of Ureaplasma urealyticum were inoculated intravaginally into groups of oestradiol-treated young adult BALB/c strain mice. Hormone treatment was essential for vaginal colonisation. The proportion of mice colonised initially and the persistence of colonisation were different with the three serovars; half of those given serovar 8 were still colonised after 84 days. A strain of serovar 5 after a further 50 subcultures in vitro was a little less persistent than it was before such subculture, but not in a way to suggest that subculturing was the main reason for differences in the behaviour of the serovars. At autopsy of six mice that were still colonised vaginally 158 days after inoculation of serovar 8, spread to the upper genital tract was shown to have occurred in three of them and dissemination to the liver and kidney in one. Compared with immunocompetent mice of strain CB20, such dissemination was not a feature in genetically related mice with severe combined immunodeficiency. This is not in keeping with the situation in hypogammaglobulinaemic patients in whom ureaplasmas and other mycoplasmas are known to disseminate. However, differences in the proportion of immunocompetent mice colonised or in ureaplasmal persistence with different serovars may act as a marker for differences in human pathogenicity and is worthy of further study.

The phenotypic and genotypic properties of Ureaplasma urealyticum (family Mycoplasmataceae, order Mycoplasmatales, class Mollicutes) are reviewed here. The 14 recognized serovar standard strains found in humans exhibit no serological cross-reactivity with ureaplasmas from other hosts and uniquely express human immuoglobulin A1 protease activity. However, they exhibit many characteristics which place them in two distinct clusters known as the parvo biovar (or biovar 1 or B) and the T960T biovar (or biovar 2 or A). Established phenotypic markers of the biovars include clustering of antigenic types, polypeptide patterns of whole-cell preparations, differential inhibition by manganese, and polymorphism among their ureases, pyrophosphatases and diaphorases. Established genotypic markers of the biovars are DNA-DNA hybridization of 60% between biovars, and distinctive RFLP patterns and genome sizes. Divergent nucleotide sequences of several highly conserved genes attest to the phylogenetic distinctiveness of the two biovars. PCRs founded upon the sequences for 16S rRNA, the 16S-23S rRNA intergenic regions, the genus-defining urease, the serovar-defining, multiple-banded antigen genes or randomly amplified polymorphic DNA tests differentiate the biovars unambiguously. With the availability of rapid, reliable and economical tests for biovar determination, it is now appropriate to propose that the taxonomic status of U. urealyticum be emended. Serovar standard strains exhibiting traits of biovar parvo (serovars 1, 3, 6 and 14) will be designated as a separate species, Ureaplasma parvum sp. nov., as befits its smaller genome size. The serovar 3 standard (strain 27T) will be the type strain of U. parvum and is represented by ATCC 27815T and NCTC 11736T. Serovar standard strains exhibiting traits of biovar T960T (2, 4, 5, 7, 8T, 9, 10, 11, 12 and 13) will retain the U. urealyticum designation and type strain, the serovar 8 standard (strain T960T), represented by ATCC 27618T and NCTC 10177T.

Ureaplasma urealyticum has been divided into 14 serovars. Recently, subdivision of U. urealyticum into two species has been proposed: U. parvum (previously U. urealyticum parvo biovar), comprising four serovars (1, 3, 6, 14) and U. urealyticum (previously U. urealyticum T-960 biovar), 10 serovars (2, 4, 5, 7-13). The multiple-banded antigen (MBA) genes of these species contain both species and serovar/subtype specific sequences. Based on whole sequences of the 5'-ends of MBA genes of U. parvum serovars and partial sequences of the 5'-ends of MBA genes of U. urealyticum serovars, we previously divided each of these species into three MBA genotypes. To further elucidate the relationships between serovars, we sequenced the whole 5'-ends of MBA genes of all 10 U. urealyticum serovars and partial repetitive regions of these genes from all serovars of U. parvum and U. urealyticum. For the first time, all four serovars of U. parvum were clearly differentiated from each other. In addition, the 10 serovars of U. urealyticum were divided into five MBA genotypes, as follows: MBA genotype A comprises serovars 2, 5, 8; MBA genotype B, serovar 10 only; MBA genotype C, serovars 4, 12, 13; MBA genotype D, serovar 9 only; and MBA genotype E comprises serovars 7 and 11. There were no sequence differences between members within each MBA genotype. Further work is required to identify other genes or other regions of the MBA genes that may be used to differentiate U. urealyticum serovars within MBA genotypes A, C and E. A better understanding of the molecular basis of serotype differentiation will help to improve subtyping methods for use in studies of the pathogenesis and epidemiology of these organisms.

A method was developed to detect Ureaplasma urealyticum in urine by the polymerase chain reaction (PCR). A 457-bp fragment of the urease gene of U. urealyticum was amplified by PCR. Before PCR, components disturbing the amplification had to be reduced. This was possible by diluting the urine 1 in 10 with distilled water and by the extraction of the U. urealyticum DNA. Urine specimens from 41 patients with systemic lupus erythematosus (SLE) and 21 healthy individuals were treated by the dilution method and investigated by PCR for U. urealyticum DNA. The results were compared with those obtained by culture and the detection rates of PCR and culture were found to be identical. Also there was no difference in the detection rates of U. urealyticum from urine of SLE patients and healthy individuals; 10 (24.4%) of the 41 urine specimens from SLE patients and five (23.8%) of the 21 urine specimens from healthy individuals gave positive results for U. urealyticum. The results of this study do not indicate a decisive role for U. urealyticum in SLE.

The importance of Ureaplasma urealyticum as a pathogen in premature neonates and patients with a profound defect in humoral immunity has, over the last few years, become well recognised. U. urealyticum is unique amongst the Mycoplasmataceae for its use of urea metabolism as an essential source of energy. The urease enzyme responsible for this is, therefore, of prime importance and any variability in expression of this enzyme may play a role in virulence of the organism. U. urealyticum is divided into 14 serovars comprising two biovars -- the parvo-biovar and T960-biovar. In this study monoclonal antibodies (MAbs) were produced against the urease enzyme. Two distinct epitopes of the 72-kDa alpha-subunit were recognised by three different MAbs. Under denaturing conditions both epitopes were shown to be specific for the parvo-biovar.