Gonnorrhea is an infectious sexually transmitted disease (STD) caused by the bacterium Neisseria gonorrhoeae that commonly reproduces in the reproductive tract.The Centers of Disease Control and Prevention (CDC) estimate that more than 700,000 individuals in the U.S. contract new gonorrheal infections per year. During recent years, there has been a progressive global increase of drug-resistant strains of gonorrhea. Therefore, there exists the necessity for health organizations to encourage the monitoring, research and development of innovative treatment regimens. We have developed multiple mathematical models to explore the gonorrheal disease state. The first objective of model formulation was to fit the model to established disease and population data provided by the CDC and U.S. Census Bureau and then include the presence of antibiotic resistance in the model. Additionally, we discuss intervention methods to combat this resistance. The second objective of model formulation was to use parameter sensitivity to determine specific age groups to target in effort to alter disease dynamics.

Neisseria gonorrhoeae is an obligate human pathogen that requires iron for its survival within the host. N. gonorrhoeae expresses high-affinity iron acquisition systems to acquire iron from host iron binding proteins. The gonococcal transferrin-iron uptake system is composed of two transferrin binding proteins, TbpA and TbpB. TbpA is a TonB-dependent, outer membrane transporter, while TbpB is a surface-exposed lipoprotein. Unlike TbpA, TbpB is not required for transferrin utilization, but makes the process more efficient. The precise mechanism by which TbpA and TbpB function to mediate transferrin-iron uptake has not been fully characterized. However, the mechanism of iron acquisition from transferrin is distinct from characterized TonB-dependent ferric-siderophore uptake systems. The transferrin-iron uptake system is unique in two ways: the involvement of the TbpB lipoprotein component and the process of iron acquisition and internalization. Unlike siderophore transporters, the transferrin-iron uptake system requires the removal of iron from transferrin for its subsequent internalization. Based on analogy with characterized TonB-dependent transporters, TbpA is proposed to consist of two distinct domains: a b-barrel and plug domain. Previous studies suggest that the plug domain has a specific role in iron internalization and this study addresses the role of the plug domain in transferrin-iron acquisition. It is thought that the TbpA plug domain facilitates iron removal from transferrin and subsequent iron binding and transport. To analyze this, iron binding by the TbpA plug domain was performed and site-directed substitution mutagenesis of putative iron-coordinating residues was carried out. From these analyses, it can be concluded that the plug domain binds iron and likely plays an active role in the process of iron internalization. Mutagenesis revealed specific residues of the plug domain critical for transferrin-iron uptake, but defects imparted by these mutations were compensated for by TbpB. Thus, this study also attempts to characterize the compensatory function provided by TbpB. Through mutagenesis, critical domains involved in the efficiency of transferrin-iron acquisition were identified. One additional study describes and characterizes a novel mechanism of TonB-independent transferrin-iron acquisition. Overall, these studies further elucidate mechanisms utilized by Neisseria gonorrhoeae in the process of iron acquisition from human transferrin.

MSc (Med), Clinical Microbiology and Infectious Diseases, Faculty of Health Sciences, University of the Witwaterstrand / Emergence and spread of resistance to ciprofloxacin among Neisseria gonorrhoeae strains has reduced the options of effective treatment for gonococcal infections and has become a concern worldwide. Up until 2008, ciprofloxacin was recommended first-line therapy for treatment of presumptive N. gonorrhoeae infections in South Africa. At the time this MSc project was conceived, ciprofloxacin was still used as first-line therapy for presumptive gonococcal infections. A real-time polymerase chain reaction (PCR) assay was used to detect ciprofloxacin-resistant N. gonorrhoeae in DNA extracted from non-invasive urine samples collected as part of the national microbiological surveillance (NMS) programme during 2006-2007. The molecular epidemiology of ciprofloxacinresistant Neisseria gonorrhoeae was investigated by sequencing the quinolone resistance determining regions (QRDR) of the gyrA and parC genes of N. gonorrhoeae and performing N. gonorrhoeae multi-antigen sequence typing (NGMAST). As part of the NMS program for sexually transmitted infections (STIs) urine and urethral swabs were collected from men presenting with urethral discharge at primary health care clinics in Johannesburg (Gauteng), Cape Town (Western Cape) and Kimberley (Northern Cape). Urine samples and cultured N. gonorrhoeae isolates from 2006-2007 were stored at -700C and available for this study. Gonococci, previously isolated from urethral swabs, were subcultured directly onto New York City media. Isolate identity was re-confirmed by typical colony morphology and biochemical tests. Urine samples from Johannesburg were tested in order to develop the real-time PCR protocol. Subsequently, paired urethral swab DNA and N. gonorrhoeae cultures were tested from NMS patients recruited in Kimberley and Cape Town. Where possible, the PCR assay results were compared with paired antibiotic susceptibility data for ciprofloxacin. Quinolone resistance determining regions (QRDR) for gyrA and parC were screened for known point mutations associated with resistance to ciprofloxacin. Detection of mutations by the real-time PCR assay generally agreed with the phenotype of either decreased susceptibility or resistance to ciprofloxacin. All ciprofloxacin resistant gonococcal isolates had the same gyrA and parC mutations, which initially suggested that quinolone resistant N. gonorrhoeae (QRNG) in Kimberley, Cape Town and Johannesburg, may be attributed to the spread of a single clone. The use of a more discriminatory typing scheme, Neisseria gonorrhoeae Multi-Antigen Sequence Typing (NG-MAST) genotyping, revealed that ciprofloxacin resistant gonococcal isolates in Johannesburg and Cape Town were heterogeneous, with sequence type (ST) 217 being most prevalent in both cities (5/16, Johannesburg; 7/11, Cape Town). In contrast, all eight QRNG isolates from Kimberley were typed as ST 533. The use of molecular methods allowed ciprofloxacin antimicrobial susceptibility determination by PCR in non-invasive specimens. This is useful in situations where bacterial cultures are unavailable or die before antimicrobial susceptibility testing can be performed. Molecular assays to detect ciprofloxacin resistance may guide physicians as to the most ideal antimicrobial combinations for individual patient treatment. As a result of emerging widespread resistance gonococci to ciprofloxacin, in 2008, the Department of Health recommended that ciprofloxacin be removed as a first line therapy in the South African national sexually transmitted infections treatment guidelines for treatment of urethritis, cervicitis and their complications. Although ciprofloxacin is no longer used as a first-line therapy to treat gonorrhoea within our country, it may still be used in cases of severe penicillin allergy or as part of multi-drug therapy for gonococcal infections in the future. The ability to detect ciprofloxacin resistance by real-time PCR will be a useful technique in such situations.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Many illnesses and infections are exacerbated and/or caused by biofilms. Neisseria gonorrhoeae, the etiologic agent of gonorrhea, is frequently asymptomatic in women, which can lead to persistent infection. Persistent infection can result in pelvic inflammatory disease, tubo-ovarian abscesses, infertility, and ectopic pregnancy. N. gonorrhoeae has been shown to form biofilms over glass, primary and immortalized cervical cells, and during natural cervical infection. Asymptomatic infection occurs in only 1% of infected males, and the infection site is subject to periodic rapid fluid flow, which may limit biofilm formation. Thus, biofilm formation may specifically play an important role in the infection of women and could contribute to the infrequent occurrence of symptoms. Prior to work presented in this dissertation, little was known about biofilm formation by N. gonorrhoeae. Therefore, we elected to compare the transcriptional profiles of biofilms to their planktonic counterparts, to identify genetic pathways involved in biofilm formation and maintenance. We found that 3.8% of the genome was differentially regulated, and that genes involved in anaerobic metabolism and oxidative stress tolerance were up-regulated in biofilm, while genes involved in aerobic metabolism were down-regulated. We determined that expression of aniA , ccp, and norB is required for robust biofilm formation over glass and human cervical cells, and anaerobic respiration occurs in the substratum of gonococcal biofilms. Disruption of the norB gene resulted in severe attenuation of biofilm formation. We determined that the accumulation of nitric oxide (NO) contributes to the phenotype of a norB mutant and can retard biofilm formation when present at sublethal concentrations. However, higher concentrations of NO can enhance biofilm formation in the absence of nitrite. NO enhances biofilm formation in an aniA mutant, but cannot completely restore biofilm formation, suggesting that NO can support anaerobic growth, although nitrite is preferred. We determined that the majority of the genes involved in gonococcal oxidative stress tolerance are required for normal biofilm formation, as mutations in the following genes resulted in biofilm attenuation over cervical cells and/or glass: oxyR, gor, prx, mntABC, trxB, and estD. Overall, biofilm formation may represent an adaptation for coping with the stresses present in the female genitourinary tract.

The aim of the diploma work was the effort to map the problems and occurrence of sexually transmissible diseases, particularly gonorrhea and syphilis, in Southern Bohemia in the time period 2000 {--} 2005. Standardized questionaries ``Report of veneral disease{\crqq} of the Ministry of Health of the Czech Republic were used. The basic set is formed by patients that contracted during the period 2000 {--} 2005 one of the four sexually transmissible diseases subject to obligatory report to the National registry of veneral diseases of the Czech Republic. Four hypotheses were proposed for the subject. The work is divided into two parts: a theoretical and a practical part. The current state of the issue is outlined in the theoretical part. Here are further described the most frequent sexually transmissible diseases, their prevention and also the social impact of prostitution and the effort to provide a legislative treatment to this problem. The practical part covers the results of analyses of data from the given question-forms and their presentation in overview tables and graphs. Case studies of patients with syphilis from the Dermatovenerogical department of the Hospital Ceske Budejovice are presented including an interesting photo documentation showing the clinical and epidemiological importance of this problem.

No description available.

Thesis (Dr. P.H.)--University of Texas Health Science Center at Houston, School of Public Health, 2007. / Source: Dissertation Abstracts International, Volume: 68-11, Section: B, page: 7288. Adviser: Michael W. Ross. Includes bibliographical references (leaves 56-61).

The transferrin iron acquisition system of Neisseria consists of two dissimilar proteins, transferrin binding protein A and B (TbpA and TbpB). TbpA and TbpB both specifically and independently bind human transferrin (Tf). TbpA is a TonB-dependent transporter, expression of which is necessary for Tf iron acquisition. In contrast, the lipoprotein TbpB is not necessary for iron internalization; however it makes this process more efficient. The role of TbpB in the transferrin iron acquisition system has not been completely elucidated. It has been suggested that TbpB is entirely surface exposed and tethered to the outer membrane by its lipid moiety. We inserted the hemagluttinin antigen (HA) epitope into TbpB in an effort to examine surface accessible and functional domains of the lipoprotein. We determined that TbpB was entirely surface exposed from just beyond the mature N-terminus. It was previously reported that the N- and C-terminus of TbpB independently bind Tf. HA epitope analysis defined both the N-terminal and C-terminal binding domains. TbpB was previously reported to play an important role in the release of Tf from the receptor. We established that TbpB exhibited a biphasic dissociation pattern; a C-terminal rapid release followed by a slower N-terminal release. These results suggested that the C-terminus plays a role in ligand turnover of the wild-type receptor. Little is known about the transport of TbpB to the outer membrane. In an attempt to identify the signals/mechanisms required for TbpB localization, the signal sequence of the protein was altered. In the absence of lipid modification, TbpB remained associated with the cell, localized to the periplasm. We also noted that internal cysteine residues were not critical for TbpB localization. Our results suggested that TbpB was transported by a lipoprotein-specific mechanism. Additionally, we demonstrated the major outer membrane secretin, PilQ, was not necessary for proper localization of TbpB. The mechanism responsible for this process remains elusive. This body of work represents the first comprehensive study of TbpB topology and function, utilizing the lipoprotein expressed in its native membrane. These results may translate to other, similar lipoprotein receptors of the pathogenic Neisseria, helping to shed light on these poorly understood proteins.

FbpA is the periplasmic binding protein of the transferrin and lactoferrin-iron transport systems. FbpA is conserved among neisserial species and is required for Neisseria gonorrhoeae to sustain growth on transferrin and lactoferrin. The identification of other putative TonB-dependent outer membrane transporters suggests that gonococci may employ other uncharacterized iron uptake systems that do not require FbpA. Previous work in our lab demonstrated that gonococcal strain FA19 utilizes iron from a number of xenosiderophores of the catecholate and hydroxamate classes. In this study we created conditional FbpA mutants to evaluate whether FbpA plays a role in the ability of gonococci to utilize iron from xenosiderophores. Strain FA19 was able to acquire iron from the xenosiderophores enterobactin and salmochelin in an FbpA-dependent and TonB-independent manner. We were also able to detect an extracellular population of FbpA indicating that FbpA may play a novel role in the internalization of iron in the absence of a dedicated transporter.