Susceptibilities of neonatal respiratory isolates of Ureaplasma urealyticum to antimicrobial agents.

Twenty-one neonatal respiratory isolates of Ureaplasma urealyticum were serotyped, and their susceptibilities to ciprofloxacin, gentamicin, chloramphenicol, erythromycin, azithromycin, and doxycycline were tested. Most patient strains were Ureaplasma urealyticum bv. parvum. Chloramphenicol, doxycycline, and azithromycin had the lowest MICs. This data may be useful when designing prophylactic or therapeutic trials of antibiotics for chronic lung disease of the newborn.

Detection of Ureaplasma urealyticum in endotracheal tube aspirates from neonates by PCR.

A PCR-based test was optimized for the detection of Ureaplasma urealyticum from neonatal respiratory specimens, with primers directed against the multiple-banded antigen gene (L. J. Teng, X. Zheng, J. I. Glass, H. Watson, J. Tsai, and G. H. Cassell, J. Clin. Microbiol. 32:1464-1469, 1994). Endotracheal tube aspirates (225) from 103 low-birth-weight neonates (<1,250 g) were taken, when possible, at days 0, 4, and 14 after birth and examined by culture and by PCR. Of 77 specimens positive by either method, 73 were detected by PCR and 60 were detected by culture. Overall, 36% of the neonates were positive for U. urealyticum by either method. Of 16 patients with PCR-positive-culture-negative results, 13 had positive cultures at another sampling point, and one additional patient had a twin with positive cultures. Of 11 patients with day 0 specimens positive by PCR alone, 9 subsequently became culture positive, demonstrating the utility of this test in early detection. Multiple serovars were present in over 50% of positive specimens, with serovars 3 and 14 in combination being most prevalent. The amplicon size generated from the specimen by PCR correctly predicted the biovars isolated in over 85% of positive specimens. Thus, this PCR test was valuable in allowing early detection of U. urealyticum in neonatal respiratory specimens, as well as in providing biovar information.

Serological response to Ureaplasma urealyticum in the neonate.

A serovar-specific antibody response to Ureaplasma urealyticum was observed in stillborns, neonates, and mothers by means of the modified metabolic inhibition test. Elevated levels of ureaplasma antibody were found in cases of stillbirth and neonatal respiratory disease. There was a higher risk of mortality among neonates with respiratory disease who had elevated levels of ureaplasma antibody. IgG and IgM serovar-specific antibody responses to U. urealyticum serovars were confirmed by the immunoperoxidase and immunofluorescence assays. In contrast to ELISA-based assays that use soluble membrane proteins as antigen, these three assays use whole intact cells. These observations suggest that the serovar-specific antibody response may be associated with the ureaplasma extramembranous carbohydrate (lypoglycan) coat, which comes off during centrifugation. With the immunoperoxidase assay, a heel-prick blood sample (20 microL) can be screened for 16 IgM or IgG + IgM + IgA (combined) responses in 4 hours. The predictive value of IgM antibody for U. urealyticum infection and other mycoplasma infections and for the risk of stillbirth and development of chronic lung disease should now be assessed.

Monoclonal antibody characterization of Jamestown Canyon (California serogroup) virus topotypes isolated in Canada.

Jamestown Canyon (JC) virus of the California (CAL) serogroup has been isolated in 12 American states and 6 Canadian provinces. A study was undertaken to produce monoclonal antibodies (MAbs) to JC virus and to use these MAbs to assay for possible heterogeneity among naturally occurring JC topotypes in Canada. MAbs were produced to the prototype strain of JC virus using BALB/c mice. Twenty-seven secreting MAbs were obtained and three of these MAbs were propagated and studied. All three MAbs, M1 (IgG1), M2 (IgG2b), and M3 (IgG2a), were reactive by immunofluorescent antibody assay against JC-infected vero cells and by ELISA against JC antigen. MAb M2 reacted with all members of the Melao complex, MAb M1 reacted only with Keystone virus, while MAb M3 exhibited no reactivity with other CAL serogroup viruses. Only MAb M3 possessed neutralization and hemagglutination inhibition activities against JC virus. The MAbs were also tested by ELISA and for neutralizing activity against 13 JC topotypes isolated in 5 provinces from Newfoundland to Saskatchewan. ELISA confirmed closer identity of the Canadian topotypes to JC as opposed to the closely related South River virus. The MAbs verified all Canadian topotypes to be JC virus but revealed different patterns of reactivity between these topotypes and prototype JC virus.

Arbovirus infections in several Ontario mammals, 1975-1980.

Serological studies for arboviruses were conducted on 725 animal sera collected in 22 Ontario townships between 1975 and 1980 including 44 coyote (Canis latrans), 277 red fox (Vulpes vulpes), 192 raccoon (Procyon lotor) and 212 striped skunk (Mephitis mephitis). Hemagglutination inhibition antibodies to two flaviviruses, namely St. Louis encephalitis and Powassan were found in 50% of coyote, 47% of skunk, 26% of fox and 10% of raccoon sera. Similarly, hemagglutination inhibition antibodies to a California serogroup virus, snowshoe hare, were found in 12% of fox, 7% of skunk, 7% of raccoon and 5% of coyote sera. No antibodies were detected to two alphavirus, namely eastern equine encephalitis and western equine encephalitis, antigens. This study affirms the endemic presence of Powassan and snowshoe hare virus and further delineates the scope of St. Louis encephalitis activity in Ontario.

Enzyme-linked immunosorbent assay typing of California serogroup viruses isolated in Canada.

A procedure was developed to type California serogroup viruses by an antibody-capture, enzyme-linked immunosorbent assay. Seven California serogroup members from North America were distinguished, including snowshoe hare, La Crosse, California encephalitis, San Angelo, Jamestown Canyon, Keystone, and trivittatus. Extensive cross-reactions were observed between Jamestown Canyon and the closely related South River strain. The enzyme-linked immunosorbent assay method was successfully applied to the typing of 77 California serogroup viruses isolated in Canada, including 61 snowshoe hare, 13 Jamestown Canyon, and 3 trivittatus topotypes.

Serological evidence of infection with California serogroup viruses (family Bunyaviridae) in residents of Long Hua, suburb of Shanghai, People's Republic of China.

Sera from 126 residents of Long Hua, a suburb of Shanghai, in the People's Republic of China, were studied. Sera were tested for haemagglutination inhibiting antibodies to alphavirus (eastern equine encephalitis, western equine encephalitis), flavivirus (St. Louis encephalitis, Powassan, dengue) and California serogroup (snowshoe hare) antigens. Flavivirus antibodies were found in 14 (11.1%) and California serogroup antibodies in 5 (3.9%) individuals. Neutralizing antibodies with highest titres to snowshoe hare virus were demonstrated in 3 of the 5 California serogroup reactors. We believe this to be the first report of California serogroup virus antibodies in Chinese residents and the first evidence to suggest that California serogroup viruses may be circulating in the Orient.

California encephalitis virus activity in mosquitoes and horses in southern Ontario, 1975.

A study was undertaken in 1975 to determine California encephalitis virus activity in southern Ontario. Three thousand and sixty-one mosquitoes, primarily Aedes species, were divided into 104 pools and inoculated into suckling mice. Isolates of snowshoe hare virus were obtained from one pool each of Aedes fitchii and A. triseriatus mosquitoes collected in the Guelph area. Serological testing of horse sera revealed extensive virus activity in southern Ontario and indicated that horses may serve as excellent monitors for California encephalitis virus.

St. Louis encephalitis in southern Ontario: laboratory studies for arboviruses.

The first reported outbreak of St. Louis encephalitis in Canada occurred in the summer of 1975 in southern Ontario -- in the Windsor-Sarnia-Chatham area, the Niagara region and the city of Toronto. Hemmagglutination inhibition and complement fixation testing of serum samples collected during the outbreak confirmed that St. Louis encephalitis virus was the etiologic agent. Furthermore, this virus was isolated from brain tissue of a patient who died. This outbreak was probably an extension of the outbreak that occurred in the United States that summer. It was the first outbreak of arbovirus encephalitis in the province of Ontario.