Genotyping of Neisseria gonorrhoeae

Genotyping of Neisseria gonorrhoeae has proved highly discriminatory. It has been used to differentiate between isolates of the same serovar, to determine the genetic relatedness of antibiotic resistant isolates and to identify isolates from sexual contacts. This level of resolution has been possible because Neisseria gonorrhoeae exhibits a high degree of genetic variability. The validity of using any typing technique to study temporal or geographical differences of an organism known to be non-clonal should, however, be carefully considered.     

Extragenital manifestations of Neisseria gonorrhoeae

Neisseria gonorrhoeae is a common cause of genitourinary sexually transmitted infections. N. gonorrhoeae is an obligate human pathogen that has evidence of tissue-specific host interactions and diverse extragenital manifestations of infection both in adult and pediatric populations. The clinical presentation of extragenital gonorrhea, diagnostic methods, treatment and preventive measures are reviewed.     

Quinolone resistance in Neisseria gonorrhoeae

Single-dose oral quinolones have been recommended for gonorrhea treatment since 1989. The antimicrobial resistance surveillance system has detected several outbreaks of quinolone-resistant gonococcal infections (QRNG), and sporadic treatment failures have been reported from high-incidence areas such as southeast Asia. QRNG may result from mutations that cause structural-functional changes in DNA topoisomerase (the quinolone target enzyme) or by changes in antimicrobial transport into the bacteria. QRNG has occurred sporadically in the United States, predominantly in persons with contact to persons in southeast Asia, and has typically occurred as an epiphenomenon in persons who were treated with other regimens. Nevertheless, this entity warrants close monitoring. The emergence of QRNG is probably related to antimicrobial misuse and overuse, in particular long-term suppressive or subtherapeutic doses.     

Quinolone resistance in Neisseria gonorrhoeae

Single-dose oral quinolones have been recommended for gonorrhea treatment since 1989. The antimicrobial resistance surveillance system has detected several outbreaks of quinolone-resistant gonococcal infections (QRNG), and sporadic treatment failures have been reported from high-incidence areas such as southeast Asia. QRNG may result from mutations that cause structural-functional changes in DNA topoisomerase (the quinolone target enzyme) or by changes in antimicrobial transport into the bacteria. QRNG has occurred sporadically in the United States, predominantly in persons with contact to persons in southeast Asia, and has typically occurred as an epiphenomenon in persons who were treated with other regimens. Nevertheless, this entity warrants close monitoring. The emergence of QRNG is probably related to antimicrobial misuse and overuse, in particular long-term suppressive or subtherapeutic doses.     

The laboratory diagnosis of Neisseria gonorrhoeae

The present article describes the laboratory diagnosis of Neisseria gonorrhoeae by culturing of the organism from different types of clinical specimens followed by confirmatory tests. The success of culture methods requires good quality collection and transport of clinical specimens. The present guide describes the media requirements and cultural conditions for N gonorrhoeae growth and the characteristics for a presumptive identification of N gonorrhoeae. Confirmatory tests include biochemical tests, chromogenic enzyme substrate tests, immunoassays and nucleic acid methods. Nucleic acid detection methods include either amplification-based methods or nonamplification tests, and are increasingly used in clinical laboratories where a viable culture is not possible to obtain. Nucleic acid methods can also be used to detect the presence of low numbers in a specimen. Nucleic acid detection methods need confirmation with another amplification method or gene target. Controls must be included to ensure true positive and negative results, and to rule out nucleic acid contamination. Monitoring of antimicrobial susceptibilities of N gonorrhoeae is important to investigate treatment failure and to evaluate the efficacy of currently recommended therapies. Many methods for the characterization of N gonorrhoeae require cultures. The useful typing methods for determining strain relatedness include auxotyping, serotyping, plasmid profile analysis, DNA sequencing of the porB gene and pulsed-field gel electrophoresis. Quality assurance programs for diagnostic testing and antimicrobial susceptibility testing is reviewed.     

Determinants of emergence of antibiotic-resistant Neisseria gonorrhoeae

Studies were carried out to evaluate the prevalence and risk factors for antibiotic-resistant Neisseria gonorrhoeae infections. Monthly surveillance of gonococcal isolates showed the prevalence of gonococci with high-level, plasmid-mediated tetracycline resistance (TRNG) to be about 15% for three consecutive 6-mo periods. Over the same period, the prevalence of gonococci with chromosomally mediated resistance to penicillin G steadily increased, from 0% to 9% and then to 21%. From April to July 1987, while chromosomally mediated penicillin resistance was rapidly increasing, a more intensive study was conducted. Patients infected with TRNG reported significantly more lifetime sexual partners (P less than .05) but otherwise resembled patients infected with antibiotic-sensitive gonococci. Patients infected with chromosomally mediated penicillin-resistant gonococci differed from other patients. In addition to reporting more lifetime partners (P less than .05), patients with chromosomally mediated penicillin-resistant gonorrhea were more likely to be older (P less than .05) and more often reported past episodes of gonorrhea (P less than .05), greater numbers of recent sexual partners (P less than .05), new sexual partners (P less than .05), prostitute contact (P = .06), and parenteral drug use or sexual partners who were drug users (P = .07). The introduction of antibiotic-resistant N. gonorrhoeae into communities may be attributable to a subset of patients who practice "risky behaviors" and who could be targeted for disease intervention activities.     

Emergence of quinolone-resistant Neisseria gonorrhoeae in Pakistan

Quinolone-resistant Neisseria gonorrhoeae (QRNG) have not been reported from Pakistan to date. This is the first report of the presence of QRNG in Pakistan. The study was performed at a tertiary care hospital laboratory in Karachi, Pakistan. Antimicrobial susceptibility data on all N. gonorrhoeae isolated between 1992 and 2002 were retrieved and analysed. Minimum inhibitory concentrations (MICs) of QRNG isolated in year 2002 were performed, and clinical information was collected. QRNG was first noted in 1999 and its proportion increased to 42% in 2002. MICs of the 12 isolates tested in 2002 showed a high level of resistance to ofloxacin with MIC of more than 4 microg/mL. Clinical information from patients with QRNG showed treatment failure. Emergence of QRNG in developing countries is alarming as there is no proper surveillance of increase in resistance. We strongly urge the need of detection and documentation of the resistant gonococcal isolates, as in vitro resistance is associated with clinical failure.     

Fluoroquinolone-resistant Neisseria gonorrhoeae: the inevitable epidemic

The worldwide incidence of fluoroquinolone-resistant Neisseria gonorrhoeae has increased dramatically in the last few years. Single doses of fluoroquinolones can no longer be used to treat N gonorrhoeae infections acquired in the Far East, parts of the Middle East, the Pacific Islands, and parts of Western Europe and the United States. Although California and Hawaii account for most of the current United States cases, the increased incidence of FQR in some high-risk groups independent of geography heralds an imminent spread of drug-resistant strains throughout the rest of the population. The use of molecular tests has revolutionized the diagnostic field in STIs. The main limitation of their application in N gonorrhoeae testing has been the loss of culture specimens that allow antimicrobial sensitivity testing. New molecular methods have made it possible to detect antimicrobial resistance without the use of live organisms. These tests hold the promise of improving epidemiologic tracking of N gonorrhoeae drug resistance, leading to better patient management at the local level. The loss of fluoroquinolones limits available oral regimens to a single CDC-recommended antibiotic, cefixime. Oral, inexpensive, single-dose alternatives are needed to ensure continued therapeutic success.     

Piliation control mechanisms in Neisseria gonorrhoeae.

Gonococci (Gc) undergo pilus+ to pilus- "phase transitions" readily in vitro. In the present study we sequenced pilin mRNA from reverting, pilus- Gc by oligonucleotide primer extension and compared these pilin mRNA sequences with those expressed by their pilus+ predecessors and pilus+ revertants. The results suggest that genetic rearrangement within the pilin structural gene can generate defective pilin gene products, resulting in a pilus- phenotype. These pilus- Gc give rise to pilus+ revertants upon reconstitution of their modified pilin gene.     

Penicillin-resistant strains of Neisseria gonorrhoeae in Shahre-Now.

Of 921 women examined, 112, or 12.1%, were identified as having gonorrhoea by positive culture; 25.6% of 78 strains isolated from the women were resistant to penicillin at 0.10 mug/ml level and 14.1% resistant at the 0.50 mug/ml level as determined by an agar dilution MIC test. Our results were compatible with a similar but larger study reported in the USA by Jaffe et al. 1976.     

Study on auxotype and serotype of Neisseria gonorrhoeae

The auxotypes of 592 strains of Neisseria gonorrhoeae isolated in Sapporo between 1980 and 1989 were investigated. The serotypes of some of these strains were also studied, and the relation between the auxotype and the sensitivity to Amoxicillin (AMPC) was analyzed. The results were as follows. 1. The auxotypes of Neisseria gonorrhoeae isolated in Sapporo were similar to those distributed in Southeast Asia. 2. In a study of the auxotypes by year, the frequency of proto and Pro- decreased, while the frequency of AHU- increased. 3. The serotypes of all strains of Neisseria gonorrhoeae investigated were WII/WIII, there was no WI serotype. 4. With respect to the relation between auxotypes and sensitivity to AMPC, the AHU- strains were more sensitive than proto or Pro-.     

淋病奈瑟菌基因工程疫苗研究概况

淋病奈瑟菌是性传播疾病淋病的致病菌,为预防和控制淋病奈瑟菌的感染,淋病奈瑟菌的疫苗已经进行了深入的研究。其中淋病奈瑟菌基因工程疫苗越来越受到关注,其能诱导机体产生特异性细胞和体液免疫应答,且是安全性最高的疫苗。本文概述了淋病奈瑟菌PorA、PorB、NspA和Tbp基因相关的基因工程疫苗的研究进展。     

In vitro effect of menfegol on Neisseria gonorrhoeae

Bacteriostatic and bactericidal effect of Menfegol, which has been used as a spermicide, on Neisseria gonorrhoeae was investigated in vitro. The distribution of the MICs of N. gonorrhoeae to Menfegol consisted of 2 groups. Resistant strains showed the MICs of more than 3200 micrograms/ml while the MICs of sensitive strains were less than or equal to 200 micrograms/ml. When the resistant strains were suspended in several concentrations of Menfegol and were incubated at 35 degrees C, no concentrations inactivated gonococci completely. However, the number of organisms was remarkably decreased within 30 minutes.