Clinical evaluation of ceftibuten in gonorrhea. A pilot study in Hong Kong

Surveillance of gonococcal antimicrobial susceptibility resulting in early detection of emerging resistance

OBJECTIVES

To undertake laboratory and clinical surveillance of gonococcal antimicrobial susceptibility to various therapeutic agents in Hong Kong, so as to monitor for emerging resistance and to inform on appropriate choice of empirical therapy.

METHODS

Trends in susceptibility of gonococci to ceftriaxone, spectinomycin, ceftibuten and azithromycin were monitored over time. Isolates with reduced susceptibility to oral extended-spectrum cephalosporins were further characterized by detection of the mosaic penA gene and typing by Neisseria gonorrhoeae multi-antigen sequence typing (NG-MAST). Correlation with clinical and epidemiological findings was undertaken on isolates positive for the mosaic penA gene.

RESULTS

Trends in susceptibility of gonococci to ceftriaxone, spectinomycin and ceftibuten remained stable between 2005 and 2010. In 2010, 30.3% of tested strains were not susceptible to azithromycin. The percentage of gonococcal strains harbouring the mosaic penA gene increased from 1.0% during April to December 2010 to 8.2% during January to September 2011 (P < 0.0001). Review of available clinical records showed that, out of 35 patients infected by strains positive for the mosaic penA gene, 30 had laboratory-documented treatment failure.

CONCLUSIONS

This study showed that ceftriaxone and spectinomycin remained effective against gonorrhoea in Hong Kong. There was an alarming increase in strains with reduced susceptibility to oral extended-spectrum cephalosporins associated with clinical treatment failure. One-third of gonococcal isolates were non-susceptible to azithromycin. The need to switch to agents other than oral extended-spectrum cephalosporins for empirical treatment is imminent. Continued surveillance with strain characterization is essential to monitor the effectiveness of currently recommended therapy.

The use of cephalosporins for gonorrhea: the impending problem of resistance

Gonorrhea remains an important clinical and public health problem throughout the world. Gonococcal infections have historically been diagnosed by Gram stain and culture but are increasingly diagnosed through nucleic acid tests, thereby eliminating the opportunity for antimicrobial susceptibility testing. Gonococcal infections are typically treated with single-dose therapy with an agent found to cure > 95% of cases. Unfortunately, the gonococcus has repeatedly developed resistance to antimicrobials including sulfonamides, penicillin, tetracyclines and fluoroquinolones. This has now left third-generation cephalosporins as the lone class of antimicrobials recommended as first-line therapy for gonorrhea in some regions. However, resistance to oral third-generation cephalosporins has emerged and spread in Asia, Australia and elsewhere. The mechanism of this resistance seems to be associated with a mosaic penicillin binding protein (penA) in addition to other chromosomal mutations previously found to confer resistance to beta-lactam antimicrobials (ponA, mtrR, penB, pilQ). Few good options exist or are in development for treating cephalosporin-resistant isolates, as most have had multidrug resistance. Preventing the spread of resistant isolates will depend on ambitious antimicrobial management programs, strengthening and expanding surveillance networks, and through effective sexually transmitted disease control and prevention.

Ceftibuten resistance and treatment failure of Neisseria gonorrhoeae infection

Neisseria gonorrhoeae infections have been empirically treated in Hong Kong with a single oral 400-mg dose of ceftibuten since 1997. Following anecdotal reports of the treatment failure of gonorrhea with oral extended-spectrum cephalosporins, the current study was undertaken to determine the antimicrobial susceptibility pattern and molecular characteristics of isolates of N. gonorrhoeae among patients with putative treatment failure in a sexually transmitted disease clinic setting. Between October 2006 and August 2007, 44 isolates of N. gonorrhoeae were studied from patients identified clinically to have treatment failure with empirical ceftibuten. The ceftibuten MICs for three strains were found to have been 8 mg/liter. These strains were determined by N. gonorrhoeae multiantigen sequence typing to belong to sequence type 835 (ST835) or the closely related ST2469. The testing of an additional eight archived ST835 strains revealed similarly elevated ceftibuten MICs. The penA gene sequences of these 11 isolates all had the mosaic pattern previously described as pattern X. Of note is that the ceftriaxone susceptibility results of these strains all fell within the susceptible range. It is concluded that ceftibuten resistance may contribute to the empirical treatment failure of gonorrhea caused by strains harboring the mosaic penA gene, which confers reduced susceptibility to oral extended-spectrum cephalosporins. Screening for such resistance in the routine clinical laboratory may be undertaken by the disk diffusion test. The continued monitoring of antimicrobial resistance and molecular characteristics of N. gonorrhoeae isolates is important to ensure that control and prevention strategies remain effective.

Update on the management of gonorrhea in adults in the United States

Gonorrhea, the second most commonly reported notifiable disease, is an important cause of cervicitis, urethritis, and pelvic inflammatory disease. The selection of appropriate therapy for gonorrhea (i.e., safe, highly effective, single dose, and affordable) is complicated by the ability of Neisseria gonorrhoeae to develop resistance to antimicrobial therapies. This article reviews the key questions and data that informed the 2006 gonorrhea treatment recommendations of the Centers for Disease Control and Prevention. Key areas addressed include the criteria used to select effective treatment for gonorrhea, the level of antimicrobial resistance at which changing treatment regimens is recommended, the epidemiology of resistance, and the use of quinolones, cephalosporins, and other classes of antimicrobials for the treatment of uncomplicated gonorrhea.

Patterns of health care utilization and health behaviors among street sex workers in Hong Kong

OBJECTIVE

To describe the current use of health services by the street-based female sex workers (FSWs) and to explore beliefs behind these health behaviors.

STUDY SETTING

Community outreach approach in a few red-light districts in Hong Kong.

STUDY DESIGN

A 30 min face-to-face interview was carried out in 89 women by direct approach and snowballing, followed by a focus group discussion drawn from the participants of the questionnaire.

RESULTS

While these FSWs' perception of personal health was good, a considerable proportion suffered from illnesses but the consultation rate was a third of the mean rate of the general population in Hong Kong. Many street workers experienced difficulty in utilizing health service in Hong Kong and even when they did, it was mainly for acute problems. Affordable access to health public services was excluded and many found private services unaffordable due to the high price charged by the practitioners. It was common for these women to self-medicate, delay in seeking medical help, or travel back to China for treatment.

CONCLUSION

The current empirical understanding of the health and health service utilization by sex workers is unbalanced. In order to reduce sexually transmitted infections (STIs) and HIV among the street sex workers, it is essential to address the fundamental issue of health care access.