4 Records out of 22207 Records

Analysis of serovar-specific immunity to Neisseria gonorrhoeae.

Author: Fudyk, Trevor Charles

Awarding University: University of Manitoba, Canada

Level : PhD

Year: 2002

Holding Libraries: University Microfilms International ;

Subject Terms: Immunology ; Neisseria gonorrhoeae ; Neisseria infections ; Gonorrhea ; Pumwani, Nairobi, Kenya ;

Abstract:

Infection with Neisseria gonorrhoeae constitutes an important cause of morbidity in human populations. The Porin protein (Por) is the major outer membrane protein of the gonococcus and displays considerable antigenic diversity among gonococcal strains. Two hypotheses to explain the diversity and dynamics of gonococcal populations is that protective, serovar- specific immunity, mediated by antibody to Por, develops following gonococcal infection, and that the development of protective immune responses within the core group act as a selective force for por antigenic heterogeneity in the gonococcal population. One core group in which gonococcal epidemiology has been studied extensively includes a collection of women working the commercial sex trade in the lower socioeconomic district of Pumwani in Nairobi, Kenya. Two experimental strategies were used to evaluate these hypotheses in a more recent longitudinal study of these female, sex workers in Nairobi, Kenya. The first line of experiments sought to examine the nature and distribution of genetic polymorphism in the Por genes of the gonococcal serovars infecting the Nairobi cohort. Nucleotide substitutions were observed predominantly in surface-exposed encoding segments of the 1a and 1b por genes. The majority of substitutions, particularly those occurring in surface- exposed encoding gene segments, resulted in amino acid change. The second line of experiments sought to determine the effect of the antibody response to por on serovar-specific gonococcal infection. Cohort women were assayed for baseline antibody responses to a recombinant 1b2 porin and a collection of polypeptides corresponding to 1b Por surface-exposed loops and followed longitudinally for gonococcal infection. Overall, antibody to the 1b2 porin appeared to provide limited protection from 1b infection, although this protective effect did not appear to extend to infection with 1a serovars. Women with antibody to 1b2 Por experienced significantly fewer homologous 1b2 and heterologous 1b3 serovar infections, compared to women without antibody. The data observed in this study support the hypothesis that the humoral immune response to Por is an important component in the ecologic interaction of human and gonococcal populations, while the generation of antigenically diverse pathogen populations act a mechanism to ensure endemic infection and pathogen survival in the face of this immune barrier. (Abstract shortened by UMI.)

Molecular epidemiology of Neisseria gonorrhoeae using newer methods.

Author: Xia, Minsheng

Awarding University: University of Washington, USA

Level : PhD

Year: 1997

Holding Libraries: University Microfilms International ;

Subject Terms: Microbiology/Neisseria infections/Gonorrhea/Neisseria gonorrhoeae/Neisseria meningitidis/Kingella denitrificans/Eikenella corrodens/Diagnostic tests/ ;

Abstract:

Gonorrhea is one of the most common human sexually transmitted diseases in the United States and the world. Discriminating and reproducible genotyping methods are needed for typing Neisseria gonorrhoeae for epidemiologic studies. In my dissertation, Pulsed-Field Gel Electrophoresis (PFGE) and Polymerase Chain Reaction (PCR) were used for typing N.Gonorrhoeae. PFGE patterns were stable with both in vitro and in vivo passaged N.Gonorrhoeae. Criteria for interpreting PFGE patterns were established based on examination of isolates from sex partners using three different enzymes. Fourteen pro/ia-6 isolates from Kenya produced 8 nhei and 7 xbai patterns. Using a combination of nhei, spei and xbai patterns, both genetic diversity and genetic relatedness were found among 16 isolates with decreased susceptibility to ciprofloxacin recovered over a two-year time period from various geographic locations. Genomic homogeneity of 68 arginine, hypoxanthine and uracil requiring ia-1,2 isolates from Seattle-King County over the past decade were examined by PFGE using nhei and xbai. Based on the criteria that isolates with $/le$1 band difference belonged to a single group, 5 nhei, 8 xbai and 11 nhei-xbai combination PFGE patterns were found. One nhei, one xbai and one nhei-xbai combination pattern accounted for 74%, 57% and 54% of the isolates respectively. A PCR assay was developed to amplify the downstream region of the incomplete tet m transposon in the 25.2 mda conjugative plasmid in 44 N.Gonorrhoeae, 12 N. Meningitidis, 4 Kingella denitrificans and 1 Eikenella corrodens isolates. One of two different PCR products of approximately 700 or 1600 base pairs was amplified. The difference between the two PCR fragments was a deletion of over 800 base pair in the smaller fragment. The two different sized pcr fragments had $>$90% DNA sequence identity with ureaplasma urealyticum tet m downstream sequences. The PCR assay was useful in differentiating the 25.2 mda plasmid. My dissertation demonstrated that PFGE had better discriminatory power than currently used typing methods for N.Gonorrhoeae. The PFGE method could be used to generate data for longitudinal molecular epidemiologic studies of gonococcal infections. Projects completed in my dissertation have laid the foundation for standardized PFGE.

The impact of Gonococcal and Chlamydial infections on maternal and child health in Africa (gonococcal infection, maternal health).

Author: Laga, Marie

Awarding University: Universitaire Instelling Antwerpen, Belgium

Level : PhD

Year: 1990

Holding Libraries: University Microfilms International ;

Subject Terms: Maternal and child health services ; Sexually transmitted diseases ; Gonorrhea ; Chlamydia trachomatis ; Nairobi, Kenya ;

Abstract:

The overall aims of this work include the definition of the aetiological roles of gonococcal and chlamydial infections in complications of pregnancy outcome and neonatal morbidity, as well as the efficacy of prophylactic and therapeutic regimens for the control of neonatal conjunctivitis in a developing country setting. A study performed in Zimbabwe showed that women with PID and women with infertility or ectopic pregnancy associated with tubal disease, had a significantly higher prevalence of IGG antibody against C. Trachomatis and N. Gonorrhoeae than pregnant control women, suggesting that both organisms are important causes of tubal sequelae following salpingitis. Several studies conducted in Nairobi, Kenya demonstrated the following: (1) the prevalence of gonococcal and chlamydial infection among labouring women was 7% and 18%, respectively; (2) maternal gonococcal but not maternal chlamydial infection was associated with preterm birth; (3) the incidence of postpartum endometritis was 20%, and both gonococcal and chlamydial infections were important risk factors for this complication; (4) in the absence of ocular prophylaxis, 42% of newborns exposed to maternal gonococcal infection developed gonococcal ophthalmia, and 31% of newborns exposed to chlamydial infection developed chlamydial ophthalmia neonatorum; (5) infants exposed to maternal chlamydial infection have a higher incidence of pneumonia during the first six months of life. Ceftriaxone (125 mg im) was 100% effective for the treatment of ocular and non-ocular neonatal gonococcal infections. Both 1% tetracycline ointment and 1% silver nitrate drops provided equally effective prophylaxis against gonococcal ophthalmia caused by multiresistant strains, and were equally less effective in preventing chlamydial ophthalmia. Public health approaches for the control of sexually transmitted diseases in mother and child are analyzed in the last chapter.

A study of gonococcal infection among a selected prostitute population in a slum area in Nairobi Kenya with particular reference to socio-economic legal aspects and intervention strategy

Author: Gakinya, Michael Njoroge

Awarding University: University of Nairobi, Kenya

Level : MPH

Year: 1985

Holding Libraries: University of Nairobi Medical Library ;

Subject Terms: Gonorrhea ; Prostitution ; Pumwani ; Nairobi ; Kenya ; Neisseria gonorrhoeae ; Spermicides ; Preventive medicine ;

Abstract:

NEISSERIA GONORRHOEA infection is a major Public Health Problem in Kenya. It is a major cause of morbidity in males and females in 'the population. Control programmes have been mainly concentrated on Seconday Prevention which concentrates on early diagnosis and treatment of Neisseria gonorrhoea infection. Primary prevention has been mainly in the form of Health Education. The target population in primary prevention has been mothers in 'Antenatal Clinics ,and the maternal Child, Health Clinics. , The major reservoir of N. Gonorrhoea infection are the: prostitutes. This study explored an alternative intervention strategy using Health Education and intravaginal spermicides as a form of Primary Prevention. A randomized control trial study using 31 ,prostitutes as control and 28 prostitutes as the study group was conducted in Pumwani Estate in Nairobi. After Health Education to both groups, the study population was instructed to insert menfegol spermicides during every sexual intercourse. Both groups were followed up every two weeks , An endocervical swab was taken from each prostitute and cultured in Modified Thayer Martin t1edium of Neisseria gonorrhoea. THs.process was repeated for every visit for a period of 12 weeks. Those infected received 2 grams of intramuscular spectinomycim. On data analysis it was found that Menfegol spermicides did not significant reduce the rate of infection in the study group. This was thought to be due to the short duration of follow up and , motivation period, the inconvenience and side effects of the in this group of prostitutes. It is recommended that the same kind of study be repeated ., using a: larger population sample. The follow up period should be longer than in this study and the spermicides should , be convenient. Spermicides to be inserted twice a day will be more appropriate. The side effect of the selected spermicides should be minimal.