Thursday, March 8, 2012

Gonorrhea

Author: Dr H. Hunter Handsfield Clinical Professor of Medicine University of Washington 2008-07-28

INTRODUCTION

Gonorrhea is one of the five originally recognized venereal diseases, along with syphilis and the now rare STDs chancroid, lymphogranuloma venereum, and Donovanosis (also known as granuloma inguinale).  The name derives from the Greek “flow of seed”, reflecting ancient perceptions that spontaneous discharge of semen explained the main symptom in men.  The causative organism, Neisseria gonorrhoeae, also known as the gonococcus, was one of the first bacteria identified and characterized at the dawn of modern microbiology in the 19th century.  Among all infections routinely reported to health authorities in the United States, gonorrhea is the second most common, following genital chlamydial infections; 358,000 cases of gonorrhea were reported in 2006, although owing to incomplete diagnosis and reporting, the true total probably was twice as high. 

The primary sites of infection are the urethra in men and the uterine cervix in women.  Infections of the rectum, acquired primarily through receptive anal intercourse, and infections of the throat, acquired primarily by penile-oral contact (fellatio), also are common in women and men who have sex with men (MSM).  As is true for most STDs, gonorrhea presents the greatest health threat in women, primarily through infection of the Fallopian tubes, called pelvic inflammatory disease (PID), the most common complication.  PID in turn often scars the Fallopian tubes, making gonorrhea a common cause of female infertility and ectopic (tubal) pregnancy.  Uncommon complications include urethral stricture (abnormal narrowing of the urethra) in men; acute testicular infection (epididymitis); disseminated gonococcal infection (DGI), in which the infection invades the bloodstream and causes a form of arthritis; and infection of the eyes of babies born to infected mothers, at one time the most common cause of blindness in much of the world.   As for all STDs associated with genital inflammation, gonorrhea enhances susceptibility and transmission of human immunodeficiency virus (HIV), contributing to the worldwide AIDS pandemic.  
This Knol addresses gonorrhea in adults.  The information on frequency, risk factors, and populations at risk reflects the epidemic in the United States and is largely applicable to industrialized countries.  Reliable epidemiologic data are lacking in most developing countries, but it is clear that the incidence, prevalence, and frequency of complications tend to be substantially higher than in the United States, with the exception of some predominantly Islamic countries.  The information in this article on symptoms, complications, treatment, and the principles of prevention applies to all geographic areas. 

HOW COMMON IS GONORRHEA AND WHO IS AT RISK?

Frequency
In the United States and many industrialized countries, gonorrhea cases are routinely reported to health authorities, such as state or local health departments.  The Centers for Disease Control and Prevention (CDC) summarize the annual data.  Reported data, however, are incomplete; many cases are not diagnosed and others are not reported or counted. Therefore special research efforts, extrapolation from limited epidemiologic analyses, and often creative interpretation of the data are needed to estimate the actual infection rates.  The incidence of a disease is the number of cases occurring over a particular time, such as infections per year).  Prevalence is the number of cases that exist at any particular moment, such as the percent of the population carrying the infection.  Both measures are used to estimate the frequency of gonorrhea and other STDs. 
This graph shows the incidence of reported gonorrhea in the United States since the early 1940s, when reliable statistics first became available.  The reported rates since the 1970s are more accurate than the earlier figures, because diagnostic tests have improved and testing is more widespread than in past years.  For example, it is likely that the true incidence in the early 1940s was at least as high as in the 1970s.  The rates of STD always rise in wartime and other times of societal stress and disruption.  The opposite effects of World War II and the post-war economic gains on gonorrhea are apparent in the figure, as is the dramatic rise associated with the sexual maturation (if not yet the emotional maturation) of the baby boom generation.  The rapid decline after the 1970s was largely due to national prevention strategies promoted by CDC.  (Prior to the 1970s, almost all public funding for STD prevention was directed toward syphilis.)  The incidence of gonorrhea has been more or less stable for a decade, with annual incidences of reported infections from 115 to 121 cases per 100,000 members of the population from 1996 through 2006.  However, the incidence rose more than 5% from 2005 to 2006, the highest proportionate increase since 1973 and a substantial concern to health authorities.  After adjusting for infections that go undiagnosed or not reported to health authorities, the 358,366 cases reported in 2006 probably reflect about 700,000 actual cases. 
The rate of gonorrhea in women is slightly higher than in men, reflecting more frequent testing of women during routine health care visits.  This figure shows the rates in 2006 by both sex and age.  As for all STDs, there is a strong association of gonorrhea with youth, although this association is less strong than for chlamydia [link to chlamydia Knol].  The highest rate of reported gonorrhea in 2006, 528 cases per 100,000, occurred in persons aged 20-24.  However, the rate of 308 per 100,000 in 15-19 year old persons translates to over 600 cases per 100,000 if you only count those teens who were sexually experienced.  In other words, considering only those people who are sexually active, the highest rate of gonorrhea occurs in teens.  In the period 1999-2002, among all United States residents 14-39 years of age, 0.24% were infected with N. gonorrhoeae, as measured by urine testing—a minimal figure that does not include infections of the rectum and throat.  This rate translates to approximately 244,000 [check] persons infected at the time of the survey.  While substantial, this rate is about tenfold lower than for chlamydial infection. 
The dominant demographic predictor of gonorrhea is race, and this figure displays the reported case rates for 2006 among the dominant race/ethnicity groupings.  The incidence was 18 times higher in African Americans – and twice as high in persons of Hispanic ancestry – as in whites.  These dramatic differences, especially between African Americans and other groups, are not primarily due to differences in sexual activity; indeed, on average African Americans and Hispanics have no greater numbers of sex partners than whites.  Rather, the explanations lie in population dynamics, the structure of sex partner networks, family stability, greater attendance by persons of lower socioeconomic attainment at public clinics where case reporting is most complete, lower average education, and lesser access to health care, among other factors.
Finally, gonorrhea rates vary widely between geographic areas and by socioeconomic status.  For example, in 2006 the highest reported rate, 370 cases per 100,000 in the Memphis metropolitan area, was more than ten-fold higher than the lowest rate, 35 per 100,000 in Boston.  Comprehensive data are available from CDC [link]. 
Of industrialized countries with reliable public health statistics, the United States has among the highest rates of gonorrhea.  The frequencies in most Western European countries are from 5 to 10 cases per 100,000 annually, more than 10-fold lower than in the United States.  These variances result largely from differences in population subgroups, the prevalence of social disruptive factors, population mobility, education level, access to health care, and related issues.  For example, most western European countries offer cost free health care and lack large minority populations analogous to African Americans and other subgroups that drive overall incidence.  The estimated rates are consistently highest where social and economic conditions preclude systematic prevention through screening, case finding, and prompt treatment, and where war and other societal stresses are maximal, such as most developing countries and some countries of Eastern Europe. 
Transmission
In adults, gonorrhea is passed from person to person almost exclusively by sexual activity.  Rare non-sexually acquired cases result from such events as childbirth, which risks infection of the baby if the mother is infected; laboratory accidents (e.g., exposure of laboratory workers’ eyes through lapses in safe technique); and maybe transmission among toddlers in conditions of crowding in tropical environments.  The common theme is that N. gonorrhoeae does not survive drying or other environmental stresses, so that transmission requires the direct exchange of infected secretions or the direct apposition of moist, infected surfaces, conditions that in adults are limited to sexual activity.  Insertive penile-vaginal and penile-anal intercourse are the dominant mechanisms, although penile-oral sex accounts for a substantial minority of cases.  Cunnilingus, i.e. oral contact with female genitals, is an inefficient mechanism that accounts for infrequent cases, for which reason gonorrhea is rare in exclusively lesbian women.  Gonorrhea is rarely if ever transmitted by kissing. 
Even for penile insertive intercourse, transmission is not 100% efficient.  The risk of transmission from men with urethral gonorrhea to their female partners has been estimated at 50% for each episode of unprotected vaginal sex, and the estimated transmission risk in the opposite direction is around 20%.  Finally, for all STDs, transmission risk mostly transmitted by infected persons without symptoms, or with only minor symptoms that do not seem important.  This happens because persons with obvious symptoms, such as abnormal discharge from the penis or vagina, and those with pain or genital sores, are less likely to be sexually active than those without such symptoms.  Therefore, gonorrhea and other STDs are selectively transmitted by those without prominent symptoms.  This fact underlies a basic STD prevention principle:  the partners of infected people need to be actively notified and treated, because those who transmitted the infection to the original patient often have nothing to warn them they might be infected and do not seek health care on their own. 

WHAT ARE THE SYMPTOMS AND SIGNS OF GONORRHEA?

The hallmarks of gonorrhea result directly from infection of the urethra in men, the cervix and sometimes the urethra in women, the rectum of either men or women, and rarely of the throat, eyes, or other sites.   
Urethral Gonorrhea in Men
The dominant symptom of urethral gonorrhea, technically called gonococcal urethritis, is abnormal discharge from the penis, typically of yellowish (pus-like) fluid, sometimes scant, but often in large amount.  A typical case is shown in this photograph.  Penile pain or discomfort, primarily upon urination, also is common.  The incubation period – the interval between infection and first symptoms – usually is three to five days, occasionally as short as two or as long as 10 days.  From 1% to 10% of cases remain asymptomatic and still more have mild symptoms, such as scant or cloudy rather than overt or yellow discharge.  The proportion of men with symptoms depends in part on specific strains of N. gonorrhoeae in the community; some strains are more likely than others to cause less symptomatic infections.   
Among all men with symptoms of urethritis (infection of the urethra), most do not have gonorrhea; chlamydia and other bacteria, which collectively cause nongonococcal urethritis (NGU), are more common.  The symptoms of gonorrhea usually are more prominent than those of chlamydia or NGU, with greater amounts of urethral discharge, a yellow or creamy appearance, and greater urinary discomfort; compare this photo of NGU with the gonorrhea image above. 
Genital Gonorrhea in Women
The primary manifestations in women result from infection of the uterine cervix and, to a lesser extent, the urethra.  Up to half of infected women remain asymptomatic, and when symptoms occur they often are mild and nonspecific; that is, the symptoms may not be notably different than day-to-day variations in the amount of vaginal discharge and other minor genital discomfort.  Women who notice gonorrhea symptoms typically have an incubation period of two to 10 days and usually experience increased vaginal discharge and sometimes urinary urgency or discomfort on urination, sometimes mimicking the symptoms of non-sexually transmitted urinary tract infection.  Bleeding between menstrual periods, sometimes heavy in amount and sometimes triggered by sex, also is common.  More women with gonorrhea than those with chlamydia have symptoms, and the amount of discharge, pain or bleeding tend to be more prominent.   
Examination by an experienced clinician may reveal mucopurulent cervicitis (MPC), indicated by inflammatory signs of the uterine cervix, such as increased redness or abnormal discharge of mucus or pus from the cervical opening.  MPC is addressed in more detail in the chlamydia Knol [link].  Sometimes the examiner can express abnormal discharge by applying pressure to the urethra or the ducts of the Bartholin glands (which provide sexual lubrication and are located on each side of the vaginal opening).  This photo shows "mucopurulent" discharge (pus mixed with mucus) emanating from the cervical opening in a woman with gonorrhea.
Other Localized Infections in Men and Women
Up to 90% of women with gonorrhea of the cervix also are infected in the urethra, explaining the high frequency of urinary discomfort in women with symptoms.  The rectum is infected in about 40% of women and MSM with gonorrhea.  Most have no rectal or anal symptoms, but some infected persons notice discharge of mucus or pus from the anus, pain, itching and sometimes rectal bleeding, and some persons observe white exudate—often described by patients as mucus—that coats feces following bowel movements.  Rectal infection in MSM is acquired by anal sex, and in women both by anal sex and contamination of the anal area by discharge from the vagina.  Gonorrhea of the throat (pharynx) is present in 5% to 10% of infected women and 10% to 20% of infected MSM, exclusively in those who perform fellatio on their male partners.  Transmission by cunnilingus is rare, so pharyngeal gonorrhea is uncommon in exclusively heterosexual men.  Most pharyngeal infections are asymptomatic, but once in a while they cause sore throat, and rarely severe manifestations that mimic strep throat, with pus visible in the back of the pharynx or on the tonsils. 
Gonococcal conjunctivitis—infection of the lining of the eyelids—is uncommon.  It can occur through auto-inoculation, as when a person with genital gonorrhea touches the eyes with contaminated fingers.  Mild cases mimic pink-eye due to common viruses, with itching and minor irritation, but severe cases can cause prominent redness and discharge of pus, and without prompt treatment can destroy the cornea, leading to blindness.  Gonococcal conjunctivitis of the newborn (ophthalmia neonatorum) once was the most common cause of blindness but now is almost completely prevented by routine testing of pregnant women to detect gonorrhea, and by routine antibiotic eye drops given to all newborns.  
Natural Course of Untreated Gonorrhea
It is commonly assumed that untreated gonorrhea or other STDs inevitably persist if not treated with antibiotics.  However, the large majority of bacterial infections of all causes, including gonorrhea, eventually are controlled by the immune system and resolve without treatment.  Before the development of modern antibiotics, uncomplicated urethral gonorrhea in men generally resolved within several weeks, although often followed by scarring that resulted in urethral stricture, with later urinary obstruction.  Infection tends to persist longer in women, but spontaneous resolution after several weeks or months is the rule, with or without intervening PID and its consequences.  However, rare cases may persist for several months, sometimes explaining positive diagnostic tests in women seemingly not at risk for new infection. 
Complications
Pelvic Inflammatory Disease.  PID refers to infection of the Fallopian tubes and is the most common complication of gonorrhea regardless of gender. Chlamydia is the most common overall cause of PID, but gonorrhea tends to be associated with more severe symptoms.  Either infection often involves other bacteria from the vagina, so that treatment requires antibiotics active against a wide range of bacteria in addition to chlamydia and gonorrhea.  Up to half of all PID cases are caused by neither gonorrhea nor chlamydia, and some are not sexually acquired.  Many such cases occur in women with prior PID, probably because damage to the Fallopian tubes predisposes to infection with normal vaginal bacteria. 
Regardless of the cause, the hallmark of PID is pain in the lower abdomen.  Infecttion often spills from the Fallopian tubes into the abdominal cavity, resulting in localized abscesses and sometimes extensive intra-abdominal infection (peritonitis).  A variant of gonococcal or chlamydial peritonitis is called perihepatitis, or the Fitz-Hugh—Curtis syndrome; it results when infection is localized around the liver and can mimic the symptoms of hepatitis or gall bladder disease.  Fever is common in women with PID but not invariably present, and sometimes the first symptom is pain in the abdomen during intercourse, because movement of the cervix is often painful in the presence of pelvic infection.  Some women are severely ill with high fever and serious pain, but others have only mild abdominal discomfort.  In addition to abdominal pain and fever, most women with PID notice abnormal vaginal discharge. 
Pelvic examination typically reveals tenderness of the uterus, ovaries, and Fallopian tubes.  Without prompt treatment, 10% to 20% of PID results in blocked the Fallopian tubes, resulting in infertility and an elevated risk of life-threatening ectopic (tubal) pregnancy.  For this reason, experts recommend treatment for possible PID even when the infection is merely suspected, without proof of the diagnosis.  Ultrasound examination often is used to document swollen or pus-filled Fallopian tubes, pelvic abscesses, and other abnormalities caused by PID.  PID sometimes is difficult to distinguish from other causes of intra-abdominal inflammation, such as endometriosis, internal pelvic bleeding during ovulation (mittelschmerz), ectopic pregnancy, appendicitis, diverticulitis, and other conditions.  
Epididymitis.  Epididymitis is the male counterpart of PID in women, with infection of the sperm collecting duct (vas defrens) and into a testicle, resulting in testicular pain, swelling, and sometimes fever.  Epididymitis is a rare complication of gonorrhea; chlamydia is a much more common cause of epididymitis.  The condition is discussed in more detail in the Knol on chlamydia. [link]   
Disseminated Gonococcal Infection.  Some strains of N. gonorrhoeae are prone to invade the blood stream, resulting in disseminated gonococcal infection (DGI).  DGI is uncommon, occurring in no more than one percent of infected people, although the actual risk varies from time to time as particular strains fluctuate in the community.  The main manifestations are arthritis and the arthritis-like condition called tenosynovitis, with pain and swelling in one or more joints (first photo), usually with fever.  About two thirds of cases include a characteristic skin rash, with scattered red bumps or pimple-like lesions (second photo).  Infection of a heart valve (endocarditis) is a rare but potentially fatal complication.  DGI is sometimes confused with reactive arthritis, an occasional complication of chlamydia [link to chlamydia Knol].  The diagnosis of DGI can be difficult, in part because the gonococcal strains most likely to cause DGI are the same ones most likely to cause genital infection without symptoms.  Therefore, many patients with DGI present with joint pain and skin rash, but without genital symptoms to alert the clinician to the possibility of gonorrhea. 

 

HOW IS GONORRHEA DIAGNOSED?

Gonorrhea can be suspected by the trained clinician, based on symptoms and physical examination.  However, there is considerable overlap between gonorrhea and NGU and cervicitis.  Therefore, laboratory testing is required for definitive diagnosis. The main diagnostic method is to identify N. gonorrhoeae at the site of infection, typically after collecting a specimen on a swab or by testing urine.  No blood test is available to detect gonorrhea. 
Microscopy and Culture
Gonococci can be readily recognized by examination of infected secretions under a microscope, after coloring the specimen with the procedure called Gram’s stain, and Gram stained smears continue in common use for rapid diagnosis of urethral gonorrhea in men.  This drawn figure illustrates the microscopic appearance of a Gram stained smear from a man with gonorrhea, with white blood cells packed with pink (“Gram negative”) kidney-shaped pairs of gonococci.  However, stained smears miss most infections of anatomic sites other than the male urethra and are not useful for diagnosis of gonorrhea in women.
Historically, culture was the preferred method for definitive diagnosis, i.e. to grow gonococci in the laboratory from specimens collected on swabs from the urethra, cervix, rectum or throat.  For the better part of a century, the culture and stained smears were the only methods available for diagnosis, but they miss many infections.  Culture remains in wide use, especially for epidemiologic surveillance, e.g. to evaluate trends in antibiotic resistance.
Nucleic Acid Amplification Tests
Tn the past 15 years culture has largely been supplanted by the nucleic acid amplification tests (NAAT), in which minute quantities of DNA can be identified in clinical specimens.  NAATs are both highly sensitive – capable of detecting almost all gonococcal infections – and highly specific, so they avoid false positive results.  NAAT methods include the polymerase chain reaction (PCR), the ligase chain reaction (LCR), the DNA strand displacement assay (SDA), and transcription mediated analysis (TMA); gonorrhea tests using each of these technologies are now the mainstay of diagnosis.   Recent research shows that the NAATs also give reliable results when used to test specimens from the rectum or throat, making the tests useful in diagnosing gonorrhea in MSM.  NAATs are discussed in more detail in the Knol on chlamydia. 

HOW IS GONORRHEA TREATED?

Authorities such as CDC recommend treatment when gonorrhea is suspected, without awaiting diagnostic confirmation.  For example, treatment is routine before test results are known for the sex partners of infected persons, and often for people with urethritis, MPC, proctitis, PID, or epididymitis even when gonorrhea is much less likely than chlamydia or other infections.  Because 10% to 50% of persons with gonorrhea are co-infected with chlamydia, treatment of gonorrhea routinely is accompanied by drugs active against chlamydia.  The table lists the regimens recommended by CDC for treatment of uncomplicated gonorrhea. http://www.cdc.gov/std/treatment/2006/toc.htm. 
Antibiotic Resistance
In the past decade, the general public has come to understand that bacteria readily develop resistance to antibiotics.  (From the perspective of the gonococcus and other bacteria, antibiotics represent a toxin in the environment, and mutants with increased resistance respond to selection pressure by propagating preferentially, an example of Darwinian evolution in action.)  N. gonorrhoeae was among the first bacteria to demonstrate this effect.  When the sulfa drugs, the first potent antibiotics, were first used in the 1930s, they were highly effective against gonorrhea, but within five years sulfa treatment was useless.  When penicillin was introduced in the 1940s, gonorrhea responded to very low doses, but within two years the dose needed for reliable cure had doubled.  This trend, with steadily increasing doses required for reliable cure, continues to the present time.  In the 1970s, N. gonorrhoeae strains evolved that were resistant to any dose of penicillin.  Increasing resistance has occurred for the tetracycline class of antibiotics, the aminoglycosides (streptomycin and related compounds), the macrolides (erythromycin and others) and, most recently, ciprofloxacin (Cipro®) and other fluoroquinolones, which until the 1990s were a worldwide mainstay of therapy. 
At present, few gonococci are resistant to the cephalosporin class of antibiotics, such as ceftriaxone (Rocephin®), cefixime (Suprax®) and others, which retain their activity against gonorrhea and are the current drugs of choice in the United States and most areas of the world.  However, even the cephalosporins do not enjoy a secure position as weapons against gonorrhea.  Gonococci with significant resistance to the cephalosporins have begun to evolve in Japan, and it may be only a matter of time before such strains appear elsewhere.  Fortunately, reduced use of some older antibiotics has been followed by re-emergence of less resistant gonococci, and newer antibiotics in development may hold promise.  For the moment, adequate treatment at relatively low cost remains widely available in industrialized countries, but these issues are critically affecting gonorrhea control in some developing countries, where the cheapest drugs—e.g., ciprofloxacin—no longer are effective. 
Antibiotics
Routine Treatment.  Compared with most bacterial infections, gonorrhea is unusual in that single dose treatment is effective.  This fortunate fact has greatly helped the control of gonorrhea, because effective treatment does not depend on the patient remembering to take a drug for several days.  The table summarizes the treatments recommended by CDC in the United States http://www.cdc.gov/std/treatment/2006/toc.htm.
                           Treatment of Uncomplicated Gonorrhea in Adults
                      Ceftriaxone (Rocephin®) 125 milligrams by intramuscular injection, single dose
                                                                     OR
                      Cefixime (Suprax®) 400 milligrams orally, single dose
                                                                    AND
                      Treatment for chlamydia with azithromycin (Zithromax®) 1 gram orally in a single dose OR                                doxycycline (Vibramycin® and others), 100 milligrams orally twice daily for 7 days (if chlamydia                       has not been ruled out by laboratory testing)
                      NOTES
                      If neither ceftriaxone not cefixime is available, substitute cefuroxime (Ceftin®) 1 gram orally OR                       cefpodoxime (Vaintin®) 400 mg orally.  Only ceftriaxone is recommended for pharngeal                                   infection.  Persons with documented allergy to the cephalosporins or serious allergic reactions to                       penicillin should be treated with spectinomycin (Trobicin®) 2 grams by intramuscular injection or                       with azithromycin (Zithromax®) 2 grams by mouth.
Ceftriaxone is highly effective against uncomplicated gonorrhea, but carries the disadvantage of requiring intramuscular injection, disliked by patients and clinicians alike.  The most effective orally administered cephalosporin antibiotic, cefixime, currently is not available in the United States, but its reintroduction is anticipated.  Cefuroxime (Ceftin®) and cefpodoxime (Vantin®) have been less well studied; they appear to be effective for genital or rectal infection, but not for gonorrhea of the throat.  When a cephalosporin cannot be given—for example, in persons allergic to such drugs—the main options are spectinomycin (Trobicin®) or azithromycin (Zithromax®) by mouth.  In the recommended doses, both of these are expensive and poorly tolerated.  All patients with gonorrhea are routinely treated for chlamydia; the regimens are described in detail in the Knol on chlamydia. 
Treatment of Complications.  PID requires prolonged treatment, usually for 10-14 days, with antibiotics that suppress not only gonorrhea but also chlamydia and many other bacteria that often co-infect the Fallopian tubes.  One example is the combination of ceftriaxone or another cephalosporin with doxycycline, often with the addition of metronidazole (Flagyl® and other brands).  Intravenous antibiotics are required for severe cases.  Prolonged therapy, often given intravenously in severe cases, is required for gonococcal epididymitis or DGI. 
Treatment of Sex Partners
Assuring treatment of partners is the responsibility of the infected person and the health care provider.  Ideally, infected persons’ partners should be professionally examined and counseled before being treated.  However, when patients are unable or unwilling to contact the partners who they believe infected them, or when partners cannot be located or contacted or refuse to seek care despite being informed, treatment is warranted even without direct examination.  This often can be accomplished by expedited partner treatment (EPT), whereby the clinician provides a prescriptions or medication for the patient to take to his or her partner.  http://www.cdc.gov/std/treatment/2006/toc.htm http://www.cdc.gov/std/ept/ EPT is discussed more thoroughly in the Knol on chlamydia.  
Follow-up Testing
Test of Cure.  The recommended treatments for gonorrhea are sufficiently reliable that routine retesting to assure cure generally is not necessary.  However, test of cure is recommended for infected persons who might be unable to comply with treatment or if atypical antibiotic regimens are used.  Test of cure should be done three weeks or more after completion of treatment.  Earlier testing risks false positive results, because NAATs can detect DNA up to two to three weeks after the organism has been killed, resulting in false positive test results. 
Rescreening.  Although routine test of cure is not usually necessary, CDC and other health agencies now advise “rescreening” in its place--that is, delayed retesting a few months after treatment.  Among men and women with either gonorrhea or chlamydia, 10% to 20% are found to be infected again when retested three to six months later.  Most cases result from reinfection, either from an untreated partner or by sex with other partners, but some cases result from persistent infection despite normally effective antibiotic treatment.  Rescreening is advised for all patients with gonorrhea or chlamydia, regardless of whether all partners were treated, whether or not condoms were used for sex following treatment, and whether or not new sex partners are believed to be at risk. 

HOW CAN GONORRHEA BE PREVENTED?

Prevention and control of STD can be viewed from the perspective of the individual at risk, who prefers to avoid infection or, if already infected, wants to prevent complications; and from the perspective of health care providers and prevention agencies, such as health departments.  These perspectives overlap with one another.  For example, health care providers are advised to routinely test patients at risk for gonorrhea, but sexually active persons can request testing when the provider does not take the initiative.  Similarly, providers should promote condom use, but only persons at risk can choose to use them. 
Public Health Prevention Strategies
A mainstay of gonorrhea prevention is laboratory-based screening, i.e., routine testing of persons at risk.  Dual NAATs that detect both gonorrhea and chlamydia are in widespread use, so that most persons tested for chlamydia also receive gonorrhea tests.  This approach is inefficient, because gonorrhea is much less common than chlamydia in most sexually active populations.  Nevertheless, such screening in women probably contributes significantly to gonorrhea control.  Among men, asymptomatic urethral gonorrhea is too uncommon to justify the expense of routine testing in most settings.  However, asymptomatic rectal and pharyngeal infections are highly prevalent in most MSM, in whom routine screening is indicated, especially in men who have had new sex partners since previously tested.   
In addition to diagnostic screening tests, important gonorrhea prevention strategies include promulgation and use of recommended treatment regimens, assuring treatment of infected persons’ sex partners, counseling and education programs, professional education of health care providers in clinical management and prevention, and surveillance through required reporting of infections to local and state health departments, which in turn permits the efficient targeting of prevention resources where needed. 
Personal Prevention
Prevention of STDs and HIV is discussed comprehensively in the Knol on Safe Sex. [link] Consistent use of condoms for vaginal or anal intercourse outside committed, mutually monogamous relationships is a core prevention strategy for all STDs and HIV infection.  Oral sex is considerably safer than genital or anal intercourse, but not risk-free.  Selection of partners at low risk, using simple, common-sense guidelines, is important in preventing gonorrhea and other STDs.  A crucial but often neglected strategy is "do ask, do tell"--i.e., to routinely ask potential partners if they are likely to be infected and to be aware of and share one's own infection history.
Sexually active persons outside mutually monogamous relationships, especially teens, young adults, and sexually active MSM of all ages, periodically should seek routine screening tests for gonorrhea, chlamydia, syphilis, HIV, and sometimes genital herpes.  The frequency of recommended screening depends on risk.  Annual testing makes sense for most sexually active young persons, but some groups at risk — such as MSM with multiple partners, sexually active teens, and commercial sex workers — should be tested as often as two to four times per year.  Finally, all sexually active persons should be aware of the common symptoms of STD and promptly seek care when such health problems appear, either in themselves or their sex partners.  

SUGGESTED READING

1.    Handsfield HH, Sparling PF.  Gonococcal Infections.  Chapter 322 in Goldman L, Ausiello D, et al (ed).  Cecil Medicine, 23rd edition.  Philadelphia, Saunders, 2007:2217-23.  An overview in a standard internal medicine textbook. 
2.    Handsfield HH. Gonorrhea.  Chapter 3 in Color Atlas and Synopsis of Sexually Transmitted Diseases, 2nd edition. New York, McGraw-Hill, 2001:22-32.  An extensively illustrated review, intended for health professionals but easily understood by all readers. 
3.    Datta SD, et al.  Gonorrhea and chlamydia in the United States among Persons 14 to 39 Years of Age, 1999 to 2002.  Annals of Internal Medicine 2007;147:89-96. The report of the most comprehensive national survey of these STDs in the US. 
4.    CDC.  Sexually Transmitted Disease Surveillance, 2006.  Atlanta, GA, November 2007. http://www.cdc.gov/std/stats/trends2006.htm  Annually updated statistics on reported STD in the US. 
5.    CDC.  Sexually Transmitted Diseases Treatment Guidelines, 2006.  Morbidity and Mortality Weekly Report 2006;55:RR-11. http://www.cdc.gov/std/treatment/2006/toc.htm CDC's treatment recommendations, including summaries of key information about all STDs. 
6.    CDC.  Expedited Partner Therapy in the Management of Sexually Transmitted Diseases, 2006. http://www.cdc.gov/std/ept/ CDC's summary of outcomes of research studies and recommendations use of streamlined approaches to assure that partners of persons with gonorrhea or chlamydia receive treatment. 
7.    Newman LM, et al.  Update on the management of gonorrhea in adults in the United States.  Clinical Infectious Diseases 2007;44:S84-101.  A review of the data that support the CDC gonorrhea treatment recommendations.