Experimental transmission of Neisseria gonorrhoeae from pregnant rat to fetus. (49/2711)

Sprague-Dawley rats were infected on day 20 of pregnancy by intraperitoneal inoculation with Neisseria gonorrhoeae. Disseminated gonococcal infection (DGI) and pelvic inflammatory disease (PID) strains in the presence of C1q but not in the presence of bovine serum albumin (BSA) were able to spread from the pregnant rat to the fetus and resulted in fetal mortality. Transmission of DGI and PID strains that are serum resistant (ser(r)) and sac-4 positive but not of a local infection strain that is ser(s) and sac-4 negative was facilitated by the C1q-dependent mechanism. This study provides the first experimental model that may mimic the transmission of gonococcal infection from mother to the fetus during pregnancy.  (+info)

Method for studying the role of indigenous cervical flora in colonisation by Neisseria gonorrhoeae. (50/2711)

A method for quantitating cervical flora has been evaluated statistically and used to study the bacterial flora of the cervix in 14 women sexually exposed to men with gonococcal urethritis. A comparison was made between those women who subsequently became colonised with Neisseria gonorrhoeae and those who did not to determine whether either total microbial populations or the different species present could be related to colonisation by N. gonorrhoeae. Two control groups of healthy women, one of patients from a public clinic and the other of patients from a private practice, were studied in the same way. Normal flora isolates were tested in vitro for antagonism or synergism toward N. gonorrhoeae or both. Cervical flora was characterised in all patient groups by wide variations between individuals, both in type and numbers of organisms. No significant differences were found in total bacterial populations or in the number of species isolated from the cervix between patient groups. Populations of N. gonorrhoeae ranged from less than 10 bacteria to log104.36. Only one normal flora isolate, a strain of Streptococcus viridans isolated from a woman exposed to but not infected by N. gonorrhoeae, demonstrated inhibition of growth towards N. gonorrhoeae.  (+info)

Bulk growth of Neisseria gonorrhoeae type 1 in a biphasic system. (51/2711)

A biphasic system for the bulk growth of Neisseria gonorrhoeae is described. It appears to combine the convenience of liquid media with the growth qualities of solid media. By using the agar in dialysis tubes rather than as slabs the surface-to-volume ratio was improved and harvesting made easier. The system is also useful in isolating gonococci from blood and joint fluids in patients with disseminated infection.  (+info)

Isolation of Chlamydia trachomatis from Bartholin's ducts. (52/2711)

Exudate from Bartholin's ducts from 30 selected patients was investigated for Chlamydia trachomatis and Neisseria gonorrhoeae. N. gonorrhoeae was isolated from the duct exudate in 24 patients and C. trachomatis in nine. Concurrent infection of the ducts was present in seven (29.2%); the remaining two patients were sexual contacts of men with non-specific urethritis. The duct exudate was mucopus in seven patients, cloudy mucus in one, and clear mucus in the other. Although contamination of the vulva by C. trachomatis derived from cervical or urethral infection cannot be excluded, three cases are described which suggest that a true infection of the duct occurs and may persist after gonococcal infection has been cured.  (+info)

Genetic diversity and mosaicism at the por locus of Neisseria gonorrhoeae. (53/2711)

The por genes of the predominant serovars of Neisseria gonorrhoeae circulating in a high-frequency transmitter core group located in Nairobi, Kenya, were examined for nucleotide sequence polymorphism. The level of por gene diversity did not differ significantly between core group-derived gonococcal strains and gonococcal strains originating elsewhere. However, por mosaicism appeared to be more frequent among core group-derived strains, suggesting that recombination of different por sequences may be a important strategy by which N. gonorrhoeae generates por gene diversity within core group populations. Despite extensive sequence variability, por expressed by gonococcal isolates of different geographic origin exhibited conserved patterns of nucleotide change, suggesting that diversity among por alleles may also be finite.  (+info)

Tyrosine phosphatase SHP-1 is involved in CD66-mediated phagocytosis of Opa52-expressing Neisseria gonorrhoeae. (54/2711)

Opa proteins of Neisseria gonorrhoeae bind to CD66 receptors on human phagocytes, thereby inducing efficient uptake of the bacteria in the absence of opsonins. The interaction of Opa proteins and CD66 receptors leads to activation of Src family tyrosine kinases, a process that is of critical importance for the efficient, CD66-mediated internalization. Here we show that during Opa-mediated stimulation of CD66 the activity of the host cell tyrosine phosphatase SHP-1 is strongly downregulated, concomitant with increases in the tyrosine phosphorylation of several cellular proteins. Since the SHP-1 tyrosine phosphorylation level itself is influenced by Opa-induced events, this phosphatase comprises an important regulatory checkpoint of the pathogen-triggered signaling cascade in human phagocytes.  (+info)

Insertion mutations in pilE differentially alter gonococcal pilin antigenic variation. (55/2711)

Pilus antigenic variation in Neisseria gonorrhoeae occurs by the high-frequency, unidirectional transfer of DNA sequences from one of several silent pilin loci (pilS) into the expressed pilin gene (pilE), resulting in a change in the primary pilin protein sequence. Previously, we investigated the effects of large or small heterologous insertions in conserved and variable portions of a pilS copy on antigenic variation. We observed differential effects on pilin recombination by the various insertions, and the severity of the defect correlated with the disruption or displacement of a conserved pilin DNA sequence called cys2. In this study, we show that disruption or displacement of the pilE cys2 sequence by the same insertions or a deletion also affects pilin recombination. However, in contrast to the insertions in pilS, the analogous insertions in pilE impaired, but did not block, recombination of the flanking pilin sequences. These results, the change in the spectrum of donor silent copies used during variation, and our previous results with pilS mutations show that the donor pilS and recipient pilE play different roles in antigenic variation. We conclude that when high-frequency recombination mechanisms are blocked, alternative mechanisms are operative.  (+info)

Decreased azithromycin susceptibility of Neisseria gonorrhoeae due to mtrR mutations. (56/2711)

Single-dose azithromycin therapy has recently been used in Uruguay for the treatment of uncomplicated gonococcal infections. As part of an active surveillance study to monitor the emergence of antibiotic resistance in gonococcal isolates, we examined the levels of azithromycin susceptibility in 51 consecutive isolates obtained from males with uncomplicated gonococcal urethritis. Isolates with decreased susceptibility to azithromycin (MICs, 0.25 to 0.5 microg/ml) were common, and these isolates often displayed cross-resistance to hydrophobic antimicrobial agents (erythromycin and Triton X-100). Resistance to erythromycin and Triton X-100 is frequently due to overexpression of the mtrCDE-encoded efflux pump mediated by mutations in the mtrR gene, which encodes a transcriptional repressor that modulates expression of the mtrCDE operon. Accordingly, we questioned whether clinical isolates that express decreased azithromycin susceptibility harbor mtrR mutations. Promoter mutations that would decrease the level of expression of mtrR as well as a missense mutation at codon 45 in the mtrR-coding region that would result in a radical amino acid replacement within the DNA-binding motif of MtrR were found in these strains. When these mutations were transferred into azithromycin-susceptible strain FA19 by transformation, the susceptibility of gonococci to azithromycin was decreased by nearly 10-fold. The mtrCDE-encoded efflux pump system was responsible for this property since insertional inactivation of the mtrC gene resulted in enhanced susceptibility of gonococci to azithromycin. We conclude that the mtrCDE-encoded efflux pump can recognize azithromycin and that the emergence of gonococcal strains with decreased susceptibility to azithromycin can, in part, be explained by mtrR mutations.  (+info)