Jerry K. Davis

Murine respiratory mycoplasmosis in LEW and F344 rats: strain differences in lesion severity.

Pathogen-free weanling rats of the LEW and F344 strains were caged together for two months to eliminate microbial and environmental differences, and then infected intranasally with 10-fold dilutions of viable Mycoplasma pulmonis. At necropsy 28 days postinoculation, F344 rats had no gross lung lesions, even those given the maximum dose of 1.4 X 109 colony-forming units of M. pulmonis. LEW rats often had extensive gross lesions with a gross-pneumonia-dose50 of 1.1 X 107 colony-forming units/rat. Histological examination of the respiratory tract (nasal passages, larynges, tracheae, and lungs) and tympanic cavities showed both qualitative and quantitative differences in lesions between the two strains, particularly in the lungs. Hyperplasia of bronchus-associated lymphoid tissue occurred in both strains, but was more extensive in LEW rats. Atelectasis, alveolar consolidation (due primarily to mononuclear inflammatory cells), and suppurative bronchitis and bronchiolitis were seen only in LEW rats. Infiltrates of lymphoid cells into the lungs distal to bronchi and around blood vessels also were seen primarily in LEW rats. These differences between the two rat strains provide excellent model systems with which to dissect the role of cell responses in the pathogenesis of a naturally occurring chronic lung disease.

Role of Ureaplasma urealyticum in amnionitis.

Ureaplasma urealyticum is commonly isolated from the amniotic fluid of unselected individuals with intact membranes at the time of cesarean section even prior to onset of labor. The risk of placental infection increases with onset of labor, rupture of membranes and number of vaginal examinations. Qualitative cultures of women with clinical signs of intraamniotic infection and matched controls indicate that U. urealyticum can be found in 50% of amniotic fluid samples of both groups thus suggesting that it may not be a cause of clinical amnionitis. To gain further understanding of the potential role of this organism, we performed amniotic fluid and blood cultures and measured serologic responses by enzyme-linked immunosorbent assay in women with clinical intraamniotic infection and matched controls. U. urealyticum was the single most common bacterial species isolated from maternal blood and amniotic fluid but the isolation rate did not differ between symptomatic and asymptomatic women. Also other known pathogenic bacteria were often isolated from amniotic fluids containing ureaplasmas. However, the marked difference in serologic response between symptomatic and asymptomatic women and the occurrence of ureaplasmemia in some suggest that in certain individuals U. urealyticum may be a cause of clinical amnionitis. Serologic responsiveness, ureaplasmemia and isolation of ureaplasmas in pure culture from amniotic fluid of some asymptomatic women suggest that U. urealyticum may also be a cause of clinically silent amnionitis. Previous studies have shown a significant association between chorioamnionitis documented by histopathology and isolation of U. urealyticum from the placenta or infant but not the maternal cervix.(ABSTRACT TRUNCATED AT 250 WORDS)

Further studies on genital mycoplasms in intra-amniotic infection: Blood cultures and serologic response

Mycoplasma hominis is recovered significantly more often in amniotic fluid of women with intra-amniotic infection than in matched control women, but Ureaplasma urealyticum is found in 50% of amniotic fluid samples of both groups. To gain further understanding, we performed blood cultures for genital mycoplasmas and measured serologic responses by a micro enzyme-linked immunosorbent assay method in women with intra-amniotic infection and in control subjects. In blood cultures of 81 women with intra-amniotic infection, M. hominis was isolated in two (2.5%) and U. urealyticum in 11 (13.6%). In 44 control blood cultures, M. hominis was not isolated, and U. urealyticum was recovered in eight (18.2%). These differences were not significant. Serologic response was determined in 86 patients. Rise in antibody to M. hominis was significantly more common in women with intra-amniotic infection and M. hominis in the amniotic fluid than in either women with intra-amniotic infection or control patients without M. hominis. For U. urealyticum antibody response was significantly more common in the intra-amniotic infection group than in control subjects, but there was no association between antibody response and isolation of this organism in amniotic fluid. When M. hominis was found in amniotic fluid or maternal blood, patients were nearly always symptomatic. The high likelihood of serologic response in these cases supports a pathogenic role of M. hominis in intra-amniotic infection. The role of U. urealyticum remains unclear.

Pathogenesis and Significance of Urogenital Mycoplasmal Infections

U. urealyticum and M. hominis can no longer be considered as harmless commensals of the lower genitourinary tract. Both can produce disease in humans. Diagnosis and management of infections due to these organisms must be based upon isolation of the organisms from the affected site and preferably the number of organisms present. Due to the frequent resistance of both organisms to tetracycline, treatment must be based upon appropriate antibiotic sensitivities. For a more detailed description of the basic biology of these organisms and isolation and identification and treatment, the reader is referred to several recent reviews.

Measurement of antibody to Mycoplasma hominis by an enzyme-linked immunoassay and detection of class-specific antibody responses in women with postpartum fever

Abstract The standard conditions for detection of human IgG, IgM, and IgA antibodies to Mycoplasma hominis by an enzyme-linked immunosorbent assay (ELISA) were established with the use of a cell lysate antigen and alkaline phosphatase conjugates. Antigen was used at a concentration of 10 μg of protein per milliliter, sera were diluted 1:200, and conjugates were diluted 1:500. Agreement between cultured isolation of M. hominis from the lower genital tract and presence of antibody in 207 women was 71%, 82%, and 86% for IgG, IgM, and IgA, respectively. When the ELISA was compared with the mycoplasmacidal assay, an overall agreement of 81% occurred, with the majority of the discrepancies occurring in the ELISA-positive and mycoplasmacidal-negative category. A linear relationship between end point titer and the A400 value (ELISA or absorbance value at 400 nm) at a standard serum dilution was demonstrated for the IgG, IgM, and IgA classes. Although the ELISA was relatively independent of antigen heterogeneity, no single strain detected more than 87% of positive sera, thus suggesting that optimum detection of antibody to M. hominis by the ELISA will require use of antigen pools derived from multiple strains of M. hominis .

Can group- and serovar-specific proteins be detected in Ureaplasma urealyticum?

Ureaplasma urealyticum has been subspeciated by a number of serologic methods. Eight serotypes have been identified by modified metabolic inhibition, growth inhibition and indirect hemagglutination. Fourteen serovars have been identified by immunofluorescence and 16 by the mycoplasmacidal assay. The present studies were performed to determine if group-specific antigens could be detected by immunofluorescence and if group- or serovar-specific antigens could be detected by enzyme-linked immunosorbent assay and immunoblotting. Reaction of rabbit antisera to U. urealyticum with homologous and heterologous serotypes based upon end point immunofluorescent titration did not differentiate the serovars into the two biotypes. In attempts to quantitate the number of a given serovar present in clinical specimens, the total number of colonies that were stained often exceeded 100%, suggesting either that the serovars represented in stock cultures are not truly representative of those present in humans or that certain strains express multiple serovar specificities. End point titration in an enzyme-linked immunoadsorbent assay using either whole cells or cell lysates and rabbit antisera failed to distinguish between group and serovars (i.e. in many cases end point titers were only 2-fold lower with heterologous antigens). Furthermore convalescent sera from patients infected with a single serovar failed to induce a serovar-specific response detectable in an enzyme-linked immunosorbent assay. Likewise immunoblotting of one dimensional electrophoretograms with sera from humans known to be infected with a single serovar showed that antibodies against that serovar recognized peptides present in all serovars and reacted with those bands with various degrees of intensity.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative Severity of Respiratory Lesions of Sialodacryoadenitis Virus and Sendai Virus Infections in LEW and F344 Rats

In several chronic diseases, lesions are more severe in LEW rats than in F344 rats. To determine whether or not acute viral diseases also are more severe in LEW rats than in F344 rats, we inoculated 6-7-week-old LEW and F344 rats with 107.2 cell culture infective units of sialodacryoadenitis virus or 104.7 infective units of Sendai virus. Twenty-four rats of each strain were given each virus. Lesions in nasal passages, tracheas, intrapulmonary airways, and pulmonary alveoli in 6 or 12 rats inoculated with each virus were assessed by scoring 5, 10, and 14 days after inoculation. Both viruses caused typical patchy necrotizing rhinitis, tracheitis, bronchitis, and bronchiolitis, with multifocal pneumonitis, in rats of both strains. Mean lesion indices for LEW rats given sialodacryoadenitis virus were significantly different from those for F344 rats for nasal passages on days 10 (0.999 vs. 0.680) and 14 (0.736 vs. 0.278), bronchi on day 5 (0.479 vs. 0.361), and alveoli on day 5 (0.677 vs. 0.275). Lesion indices for LEW rats given Sendai virus were significantly different from those for F344 rats for nasal passages on days 10 (1.000 vs. 0.611) and 14 (0.778 vs. 0.583); trachea on day 10 (0.625 vs. 0.028); bronchi on days 5 (0.476 vs. 0.331), 10 (0.123 vs. 0.013), and 14 (0.038 vs. 0); and alveoli on days 5 (0.413 vs. 0.114) and 10 (0.18 5 vs. 0.020). Thus, at the tested doses, both viruses caused more severe respiratory tract lesions in LEW rats than in F344 rats.

Murine Respiratory Mycoplasmosis, Rat and Mouse

Synonyms. Murine chronic respiratory disease, infectious catarrh, chronic murine pneumonia, enzootic bronchiectasis

The effects of three serotypes of Ureaplasma urealyticum on spermatozoal motility and penetration in vitro**Supported by grant HD-16199 from the National Institute of Child Health and Human Development, Bethesda, Maryland.††Presented in part at the International Organization of Mycoplasmology International Symposium on Ureaplasmas of Humans: With Emphasis on Maternal and Neonatal Infections, Seattle, Washington, October 10 to 12, 1985.

The effects of incubation of spermatozoa with three serotypes of Ureaplasma urealyticum on spermatozoal motility and penetration in vitro were investigated. Using computer-assisted videomicroscopy, three parameters of motility were determined: individual path lengths, individual vectorial distances, and percentage motility. Polyacrylamide gels were used as a medium for assessment of spermatozoal penetration. Ureaplasma-infected spermatozoa did have significantly greater path lengths and individual distances than did uninfected controls, but Ureaplasma infection had no significant effect on percentage motility. Overall, there were no significant differences in penetration distances between Ureaplasma-infected spermatozoa and their corresponding uninfected controls. Our conclusion is that the Ureaplasmas did not adversely affect motility or penetration when spermatozoa were incubated with Ureaplasmas for 45 minutes at Ureaplasma:sperm ratios as high as 100:1.

Measurement of antibody to Mycoplasma hominis by an enzyle-linked immunoassay and detection of class-specific antibody responses in women with postpartum fever

The standard conditions for detection of human IgG, IgM, and IgA antibodies to Mycoplasma hominis by an enzyme-linked immunosorbent assay (ELISA) were established with the use of a cell lysate antigen and alkaline phosphatase conjugates. Antigen was used at a concentration of 10 micrograms of protein per milliliter, sera were diluted 1:200, and conjugates were diluted 1:500. Agreement between cultured isolation of M. hominis from the lower genital tract and presence of antibody in 207 women was 71%, 82%, and 86% for IgG, IgM, and IgA, respectively. When the ELISA was compared with the mycoplasmacidal assay, an overall agreement of 81% occurred, with the majority of the discrepancies occurring in the ELISA-positive and mycoplasmacidal-negative category. A linear relationship between end point titer and the A400 value (ELISA or absorbance value at 400 nm) at a standard serum dilution was demonstrated for the IgG, IgM, and IgA classes. Although the ELISA was relatively independent of antigen heterogeneity, no single strain detected more than 87% of positive sera, thus suggesting that optimum detection of antibody to M. hominis by the ELISA will require use of antigen pools derived from multiple strains of M. hominis.