Gonorrhea

Background

Gonorrhea is the second most commonly reported notifiable disease in the United States. Infections due to Neisseria gonorrhoeae, like those resulting from Chlamydia trachomatis, are a major cause of pelvic inflammatory disease (PID) in the United States. PID can lead to serious outcomes in women, such as tubal infertility, ectopic pregnancy, and chronic pelvic pain. In addition, epidemiologic and biologic studies provide evidence that gonococcal infections facilitate the transmission of HIV infection.¹ Together, sexual behavior and community prevalence can increase the risk of acquiring gonorrhea. Social determinants of health, such as socioeconomic status, discrimination, and access to quality health care, may contribute to the burden of gonorrhea in a community.²

In 2009, the national rate of reported gonorrhea cases reached an historic low of 98.1 cases per 100,000 population (Figure 12, Table 1). However, during 2009–2012, the rate increased slightly each year to 106.7 cases per 100,000 population in 2012. In 2013, the rate decreased slightly to 105.3 cases per 100,000 population and then during 2013–2015, the rate increased each year. In 2015, a total of 395,216 cases were reported for a rate of 123.9 gonorrhea cases per 100,000 population (Figure 12, Table 1).

The increase in the gonorrhea rate during 2014–2015 was observed among both males and females; however, the increase was larger among males (Figure 13). During 2014–2015, the gonorrhea rate increased in all regions and during 2011–2015, with the largest increase in the West (92.2%; 61.4 to 118.0 cases per 100,000 population) (Figure 14, Table 14). The rate of gonorrhea continued to increase among persons in every age group among those aged 15 years and older during 2014–2015 (Table 21).

N. gonorrhoeae has progressively developed resistance to each of the antimicrobials used for treatment of gonorrhea. Most recently, declining susceptibility to cefixime (an oral cephalosporin antibiotic) resulted in a change to the CDC treatment guidelines, so that dual therapy with ceftriaxone (an injectable cephalosporin) and azithromycin is now the only CDC-recommended treatment regimen for gonorrhea.³ The emerging threat of cephalosporin resistance highlights the need for continued surveillance of N. gonorrhoeae antimicrobial susceptibility.

The combination of persistently high gonorrhea morbidity in some populations and the threat of cephalosporin-resistant gonorrhea reinforces the need to better understand the epidemiology of gonorrhea.

Interpreting Rates of Reported Cases of Gonorrhea

Although gonorrhea case reporting is useful for monitoring disease trends, the number of gonorrhea cases reported to CDC is affected by many factors in addition to the actual occurrence of the infection within the population. Changes in the burden of gonorrhea may be masked by changes in screening practices (e.g., screening for chlamydia with tests that also detect N. gonorrhoeae infections or increased screening at extra-genital anatomic sites), the use of diagnostic tests with different test performance (e.g., the broader use of nucleic acid amplification tests [NAATs]), and changes in reporting practices. As with other STDs, the reporting of gonorrhea cases to CDC is incomplete.⁴ For these reasons, supplemental data on gonorrhea prevalence in persons screened in a variety of settings are useful in assessing the burden of disease in selected populations.

Gonorrhea — United States

In 2015, a total of 395,216 cases of gonorrhea were reported in the United States, yielding a rate of 123.9 gonorrhea cases per 100,000 population (Table 1). Since 2014, the rate of reported gonorrhea cases increased 12.8% since 2014, and increased 19.9% since 2011.

Gonorrhea by Region

In 2015, as in previous years, the South had the highest rate of reported gonorrhea cases (146.3 cases per 100,000 population) among the four regions of the United States, followed by the West (118.0 cases per 100,000 population), the Midwest (115.7 cases per 100,000 population), and the Northeast (94.2 cases per 100,000 population) (Figure 14, Table 14). This is the first year that the West has had a higher rate than both the Midwest and Northeast. During 2014–2015, the gonorrhea rate increased in all four regions: 18.1% in the West, 12.6% in the South, 11.6% in the Northeast, and 8.9% in the Midwest (Figure 14, Table 14). During 2011–2015, the rate of gonorrhea in the West increased by 92.2% (61.4 to 118.0 cases per 100,000 population) while other regions had smaller overall increases during this time period (i.e., 10.3% in the Northeast, 9.3% in the South, and 4.4% in the Midwest).

Gonorrhea by State

In 2015, rates of reported gonorrhea cases per 100,000 population ranged by state from 18.5 in New Hampshire to 221.1 in Louisiana; the gonorrhea rate in the District of Columbia was 416.2 cases per 100,000 population (Figure 15, Table 13).

During 2014–2015, gonorrhea rates increased in 80% of states and the District of Columbia, decreased in 18% of states, and remained the same in 2% (Table 14).

Gonorrhea by Metropolitan Statistical Area

The overall rate of reported gonorrhea cases in the 50 most populous metropolitan statistical areas (MSAs) was 137.0 cases per 100,000 population in 2015 and represents a 12.9% increase compared with the rate in 2014 (121.4 cases per 100,000 population) (Table 17). In 2015, 60.6% of reported gonorrhea cases were reported by these MSAs. Since 2011, the gonorrhea rate among females in the 50 most populous MSAs has been lower than the rate among males (Tables 18 and 19). In 2015, the rate among females in these MSAs was 107.0 cases per 100,000 females, while the rate among males was 167.9 cases per 100,000 males.

Gonorrhea by County

In 2015, 51% of reported gonorrhea cases occurred in just 70 counties or independent cities (Table 20). In 2015, 806 counties (25.7%) in the United States had a rate less than or equal to 16 cases per 100,000 population (Figure 16). The rate ranged from 17 to 41 cases per 100,000 population in 766 counties (24.3%), ranged from 42 to 97 cases per 100,000 population in 787 counties (25.1%), and was more than 97 cases per 100,000 population in 782 counties (24.9%). As in previous years, counties with the highest gonorrhea rates were concentrated in the South.

Gonorrhea by Sex

As was observed during 2013–2014, the rate of reported gonorrhea cases among males was higher than the rate among females in 2015 (Figure 13, Tables 15 and 16). During 2014–2015, the gonorrhea rate among males increased 18.3% (119.0 to 140.9 cases per 100,000 males), and the rate among females increased 6.8% (100.4 to 107.2 cases per 100,000 females). During 2011–2015, the rate among males increased 44.2% (97.7 to 140.9 cases per 100,000 males), while the rate among females decreased 0.7% (108.0 to 107.2 cases per 100,000 females). The magnitude of the increase among males suggest either increased transmission or increased case ascertainment (e.g., through increased extra-genital screening) among gay, bisexual, and other men who have sex with men (collectively referred to as MSM). However, most jurisdictions do not routinely report sex of sex partner or site of infection for gonorrhea cases, so trends in gonorrhea rates among MSM over time cannot be assessed.

Gonorrhea by Region and Sex

In all regions, the rate of gonorrhea increased among both males and females during 2014–2015 and the rate of increase among males was larger than the rate of increase among females (Tables 15 and 16). The rate of reported gonorrhea cases increased the most in the West (20.7% among males and 13.8% among females) and in the South, where the rate of reported gonorrhea cases increased 19.2% among males and 6.2% among females (Tables 15 and 16).

Gonorrhea by Age

In 2015, rates of reported gonorrhea cases continued to be highest among adolescents and young adults (Figure 17, Table 21). In 2015, the highest rates among females were observed among those aged 20–24 years (546.9 cases per 100,000 females) and 15–19 years (442.2 cases per 100,000 females). Among males, the rate was also highest among those aged 20–24 years (539.1 cases per 100,000 males) and 25–29 years (448.8 cases per 100,000 males).

In 2015, persons aged 15–44 years accounted for 92.7% of reported gonorrhea cases with known age. Among 15–19 year olds, rates decreased during 2011–2014; however, during 2014–2015, rates increased 5.2%. During 2014–2015, the gonorrhea rate also increased among other age groups: 7.2% among those aged 20–24 years, 19.1% among those aged 25–29 years, 19.0% among those aged 30–34 years, 25.7% among those aged 35–39 years, and 18.5% among those aged 40–44 years (Figures 18 and 19, Table 21). Among persons aged 15–44 years, increases were observed in all age groups for both men and women.

Gonorrhea by Race/Ethnicity

In 2015, among the 50 states that submitted data in the race and ethnicity categories according to Office of Management and Budget (OMB) standards (see Appendix A Section A1.5), the rate of reported gonorrhea cases remained highest among Blacks (424.9 cases per 100,000 population) (Table 22B). The rate among Blacks was 9.6 times the rate among Whites (44.2 cases per 100,000 population). The gonorrhea rate among American Indians/Alaska Natives (192.8 cases per 100,000 population) was 4.4 times that of Whites, the rate among Native Hawaiians/Other Pacific Islanders (123.0 cases per 100,000 population) was 2.8 times that of Whites, the rate among Hispanics (80.5 cases per 100,000 population) was 1.8 times that of Whites, and the rate among Asians (22.9 cases per 100,000 population) was half the rate of Whites (Table 22B).

During 2011–2015, among the 45 states that submitted race and ethnicity data according to OMB standards (see Appendix A Section A1.5) for all five years during that period, the gonorrhea rate increased among Whites (75.1%), American Indians/Alaska Natives (71.3%), Asians (70.0%), Native Hawaiians/Other Pacific Islanders (61.0%), and Hispanics (53.8%) (Figure 20). During this same time period, the gonorrhea rate decreased 4.0% among Blacks.

More information on gonorrhea rates among race and ethnicity groups can be found in the Special Focus Profiles.

Gonorrhea by Reporting Source

In 2015, 11.9% of gonorrhea cases were reported from STD clinics, 74.2% were reported from venues outside of STD clinics, and 13.9% had an unknown source of report (Table A2).

During 2006–2015, the number of gonorrhea cases reported by STD clinics declined 60.1% among males and 53.3% among females. During 2014–2015, the number of gonorrhea cases reported by STD clinics continued to decrease; 12.2% among males and 4.9% among females (Figures 21 and 22).

In 2015, among males, private physicians/health maintenance organizations (HMOs) (20.3 %) and STD clinics (15.1 %) were the most common reporting sources, followed by other hospital clinics/facilities (11.5%), other health department clinics (8.9%), and emergency rooms (5.9%) (Figure 21). Among females, private physicians/HMOs (24.8%) were the most common reporting source, followed by other hospital clinics/facilities (12.7%), STD clinics (7.8%), family planning clinics (7.6%), and other health department clinics (6.8%) (Figure 22).

STD Surveillance Network

The STD Surveillance Network (SSuN) is an ongoing collaboration of states and independently funded cities collecting enhanced information on a representative sample of gonorrhea case reports received from all reporting sources in their jurisdiction. Enhanced gonorrhea case report data for this report were obtained from Cycle 3 of SSuN, which includes 10 jurisdictions, of which 8 collected data on randomly sampled cases in 2015. SSuN collaborators interviewed 2,278 gonorrhea cases representing 3% of total morbidity reported from participating jurisdictions during that time period. The estimated burden of disease represented by MSM, men who have sex with women only (MSW), and women varied substantially across collaborating sites (Figure 23). San Francisco had the highest proportion of estimated MSM cases (87.8 %), while the lowest proportion of morbidity estimated to be attributed to MSM was found in Baltimore at 16.9% (Figure 23). Across all SSuN collaborating jurisdictions in 2015, 42.2% of gonorrhea cases were estimated to be among MSM, 25.4% among MSW, and 32.4% among women.

Clinic data for this report include information from patients attending STD clinics during 2015 in the 10 jurisdictions participating in Cycle 3 of SSuN. In 2015, the proportion of STD clinic patients who tested positive for gonorrhea varied by age group, sex, and sex of sex partner (Figure 24). Among those attending these clinics, MSM disproportionately had higher positivity rates when compared to MSW and women in all age groups. While positivity rates declined with increasing age for heterosexual males and females, a much slower decline by age was seen in MSM.

Additional information about SSuN methodology can be found in Appendix A Section A2.2 .

Gonococcal Isolate Surveillance Project

Antimicrobial resistance remains an important consideration in the treatment of gonorrhea.^3,5–7 In 1986, the Gonococcal Isolate Surveillance Project (GISP), a national sentinel surveillance system, was established to monitor trends in antimicrobial susceptibilities of urethral N. gonorrhoeae strains in the United States.⁷ Data are collected from selected STD clinic sentinel sites and from regional laboratories (Figure 25).

Antimicrobial susceptibility is measured by the minimum inhibitory concentration (MIC), the lowest antimicrobial concentration that inhibits bacterial growth in the laboratory. Increases in MICs demonstrate that the bacteria can survive at higher antimicrobial concentrations in the laboratory. Monitoring of MIC trends is useful because increasing MICs can oftentimes be an early indicator of the emergence of antimicrobial resistance.

Information on the antimicrobial susceptibility criteria used in GISP can be found in Appendix A Section A2.3. More information about GISP and additional data can be found at https://www.cdc.gov/std/GISP.

Ceftriaxone Susceptibility

Susceptibility testing for ceftriaxone began in 1987. During 2007–2015, the percentage of GISP isolates that exhibited elevated ceftriaxone MICs, defined as ≥0.125 μg/ml, fluctuated between 0.1% and 0.4% (Figure 26). Five isolates with decreased ceftriaxone susceptibility (MIC = 0.5 μg/ml) have been previously identified in GISP: one from San Diego, California (1987), two from Cincinnati, Ohio (1992 and 1993), one from Philadelphia, Pennsylvania (1997), and one from Oklahoma City, Oklahoma (2012).

Cefixime Susceptibility

Susceptibility testing for cefixime began in 1992, was discontinued in 2007, and was restarted in 2009. The percentage of isolates with elevated cefixime MICs (≥0.25μg/ ml) declined from 1.4% in 2011 to 0.5% in 2015 (Figure 26).

Azithromycin Susceptibility

Susceptibility testing for azithromycin began in 1992. Figure 27 displays the distribution of azithromycin MICs among GISP isolates collected during 2011–2015. Most isolates had MICs of 0.125–0.5 μg/ml. During 2011–2013, the percentage of isolates with reduced azithromycin susceptibility (MICs ≥ 2 μg/ml) ranged from 0.3% to 0.6%; during 2013–2015, the percentage increased from 0.6% to 2.6%.

Ciprofloxacin Susceptibility

During 1999–2007, the percentage of isolates that were resistant to ciprofloxacin increased from 0.4% to 14.8%. The percentage declined in 2008 and 2009 and then increased. In 2015, 22.3% of GISP isolates were resistant to ciprofloxacin. Among isolates from MSM, 32.1% were resistant; 16.4% of isolates from MSW exhibited ciprofloxacin resistance.

Susceptibility to Other Antimicrobials

In 2015, 39.6% of isolates collected from GISP sites were resistant to penicillin, tetracycline, ciprofloxacin, or some combination of those antimicrobials (Figure 28). Although these antimicrobials are no longer recommended for treatment of gonorrhea, the resistance phenotypes remain common. Conversely, 60.4% of isolates were susceptible to all three of these antimicrobials.

Antimicrobial Treatments Given for Gonorrhea

The antimicrobial agents given to GISP patients for gonorrhea therapy are shown in Figure 29. The proportion of patients treated with ceftriaxone 250 mg increased from 84.0% in 2011 to 96.9% in 2013, then decreased to 94.4% in 2015. In 2015, 1.5% of patients were treated with azithromycin 2 grams as monotherapy and 17 patients (0.3%) were treated with cefixime.

Gonorrhea Among Special Populations

More information about gonorrhea in race/ethnicity groups, women of reproductive age, adolescents, and MSM can be found in the Special Focus Profiles.

Gonorrhea Summary

The national rate of reported gonorrhea cases reached a historic low in 2009, but increased each year during 2009–2012. After a temporary decrease in 2013, the gonorrhea rate increased again during 2014–2015. This increase was largely attributable to increases among men. High gonorrhea rates persist in certain geographic areas, among adolescents and young adults, and in some racial/ethnic groups.

GISP continues to monitor for the emergence of decreased susceptibility and resistance to cephalosporins and azithromycin.

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