Group B streptococcal strains, representing the five major serotypes, were inoculated into infant rats by intranasal, oral, and intraperitoneal routes. Bacteremia regularly followed injection by the intraperitoneal route. Four strains (three of type III) isolated from human cerebrospinal fluid appeared more virulent for 5-day-old rats. Injection of fewer than 10 colony-forming units of one strain, a type III, led to bacteremia and death in 27% of animals. The cumulative bacteremia and mortality rate with this strain was 66% in animals given inocula of less than 10 to 10(3) colony-forming units. Bacteremia developed by 24 to 48 h with concentrations of greater than 10(5) colony-forming units per ml of blood, and death occurred soon afterward. Among bacteremic animals, positive cerebrospinal fluid cultures were found in 97%, and cerebrospinal fluid bacterial concentrations were equal to or exceeded bacterial counts in blood. The susceptibility of infant rats to infection with type Ia, Ic, or III strains was age dependent. Histopathological studies of the brain and meninges in 34 bacteremic animals with culture-positive cerebrospinal fluid revealed that 5- to 10-day-old animals had numerous bacteria distributed in a perivascular pattern but, with one exception, no leukocytic infiltration. In contrast, three of the 11- to 12-day-old and two 15-day-old animals had very thickened meninges infiltrated with polymorphonuclear leukocytes, macrophages, and bacteria.
Aims-To determine whether oro-pharyngeal colonisation by Chlamydia trachomatis occurs in patients at risk of genital chlamydia infection; to determine whether screening pharyngeal specimens by polymerase chain reaction (PCR) increases detection of C trachomatis compared with isolation and the immune dot blot test; and to correlate the detection of C trachomatis and Neisseria gonorrhoeae in the pharynx with a history oforo-genital contact.Methods-Thirteen homosexuals and 11 heterosexuals were included in the study.Urogenital and pharyngeal specimens were tested for C trachomatis and N gonorrhoeae using standard clinical diagnostic procedures. Two different PCR methodologies were also used to detect C trachomatis in the pharyngeal specimens. Results were correlated with the mode of sexual practice. Results-Oro-genital sexual contact was practised by 64*9% (72/111) of heterosexuals in addition to penetrative penovaginal intercourse. Additionally, 62-1% (77/124) of all patients did not use any form of barrier protection. Of those who admitted to oro-genital sexual contact, 17*6% ofpatients with a genital chlamydial infection and 36-4% of those with genital gonorrhoea also had asymptomatic pharyngeal colonisation. C trachomatis was detected in three of 124 (2-4%) pharyngeal specimens by PCR which were reported as negative by chlamydial culture; one was positive by the immune dot blot test. Conclusion-The majority of patients practised unprotected oro-genital contact and significant pharyngeal colonisation by C trachomatis and N gonorrhoeae occurred if genital infection was present. Despite the use of PCR in a population at high risk of sexually transmitted disease, the prevalence ofchlamydia in the pharynx was very low. This indicates that transmission of C trachomatis to the oropharynx does not pose a serious health risk and that screening of patients for oropharyngeal C trachomatis is not worthwhile. (J Clin Pathol 1995;48:658-
Two strains of Mycoplasma pulmonis (associated with infectious catarrh) on examination in fluid culture (20% horse serum-bouillon) by phase microscopy were highly pleomorphic, with many bacilliform elements and fewer coccoid ones. Motility, characterized by gliding of rods and spinning of spherical forms, was observed through the 9th subculture of one strain and the 15th of the second. Motile elements were not seen in later transfers and pleomorphism was reduced. One strain of M. neurolyticum (associated with conjunctivitis and encephalitis) was much less pleomorphic and showed neither bacilliform elements nor motility at any time. When examined by negative-contrast electron microscopy, organisms of this strain were found to have an average diameter of 0.7 ,u and to possess a concentrated peripheral layer of cytoplasm and a central mass which may represent the cells' nuclear equivalent. The latter feature was not prominent in spherical forms of M. pulmonis. These cells, when observed after 48 hr of culture, showed evidence of the generation of new progeny cells in their central area. The filamentous or bacilliform cells of M. pulmonis were frequently serpentine in appearance, 2.0 to 3.0 it in length and 80 to 250 m,u in width. They appeared to generate new cells from terminal buds from which outpouchings initially developed. Older cells, in the stationary phase, showed evidence of undergoing multipolar germination. Microtubules, about 60 m,u wide, were found in association with most filamentous cells from 48-hr cultures; fragments of membrane, studded with closely packed ribosomelike particles, were also found. There was no evidence of flagella or any specialized structure that could account for the observed motility of the organisms.
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