The bacterium Neisseria gonorrhoeae causes gonorrhea, one of the world’s most significant infectious diseases, on the rise, and affects the reproductive tract and urethra. It is often asymptomatic in women, highly contagious, and can lead to serious complications.

Gonorrhea is the second most common bacterial Sexually Transmitted Infection (STI), with a significant morbidity rate and a high economic cost worldwide. It is transmitted through unprotected sexual contact, including vaginal, anal, and oral sex, with people infected with gonorrhea.

According to the Pan American Health Organization (PAHO), gonorrhea is the most antibiotic-resistant of all STIs. There is a growing resistance to most of the antibiotics used to treat gonorrhea infections, which limits treatment options. Currently, antimicrobial resistance poses a major obstacle to reducing the global burden of gonorrhea. The World Health Organization (WHO) estimates that in 2020 there were 82 million cases of gonorrhea, which can increase the risk of infection with the Human Immunodeficiency Virus (HIV) and are a major cause of pelvic inflammatory disease and female infertility.

In light of this critical global health situation, scientists at the National Polytechnic Institute (IPN) are working to improve the diagnosis of STIs in Mexico, as the high incidence and prevalence of these diseases pose a challenge to sexual and reproductive health.

The Medical Bacteriology Laboratory in the Department of Microbiology at the National School of Biological Sciences (ENCB), Santo Tomás Campus, has maintained a research program on STIs since 2007, and the data generated over the years has led to an interdisciplinary project on gonorrhea, in collaboration with various colleagues from the IPN, the Autonomous Metropolitan University (UAM), Lerma Campus, and clinics specializing in sexually transmitted infections in Mexico City—the only clinics of their kind in the country—the Condesa Specialized Clinic (CEC) and the Condesa Iztapalapa Specialized Clinic (CECI).

The head of the study is the director of the ENCB’s bacteriology laboratory, Ma. Guadalupe Aguilera Arreola, whose project began in 2024 and will conclude this year. She commented that “this research group came together to study this infection in patients seeking help or medical care at these clinics. In addition to determining the frequency of infection, one of main interests has been antimicrobial resistance, frequency of the infection, is the bacteria responsible for this infection. Over the past two years, we have found evidence showing that gonorrhea is more common than we initially believed; more than 30% of the patients we were able to recruit for the study have gonorrhea,” she said.

Limited access to diagnosis and treatment, together with antimicrobial resistance, complicates the early detection and proper management of STIs, exacerbating their impact on public health, in addition to the lack of equitable coverage within the healthcare system.

COMBATING STIs

For this reason, the project aims to investigate and address these barriers, evaluate prevention strategies, and analyze diagnostic challenges and trends in antimicrobial resistance, in collaboration with health institutions and the government, with the goal of improving patient care and contributing to public health in Mexico.

Another objective is to describe the frequency of gonorrhea resistance to antimicrobial treatment in the vulnerable population served by the two specialized clinics and to implement a comprehensive bacteriological diagnosis, as well as phenotypic and molecular typing of the causative agent N. gonorrhoeae, in order to provide epidemiological information on this health problem—information that is currently not precisely known in Mexico and that is urgently needed to strengthen appropriate prevention measures to reduce the spread of antimicrobial-resistant strains.

The bacteriologist explained that one of the unique aspects of this study is that the researchers decided to focus their efforts on recruiting men who have sex with men and who were experiencing symptoms.

“Only symptomatic men who sought help and met the inclusion criteria were sampled, and in this population, only 30% of the cases corresponded to gonorrhea, although they also had other sexually transmitted infections,” Aguilera Arreola stated in an interview with the Conversus News Agency (AIC).

The Level II researcher in Mexico’s National System of Researchers (SNII) emphasized that, among the Mexican population living with sexually transmitted infections, gonorrhea was the most common, and this project focuses on identifying these patients and offering them a more accurate diagnosis.

“We collect and process samples and provide physician with the results, which allows for appropriate adjustments to the treatment plan. It’s a way to support the healthcare services provided by these clinics; this way, if the initial treatment wasn’t appropriate, it can be changed in time so that these patients have a shorter recovery period. From that perspective, the project helps doctors manage their patients,” she said.

Dr. Aguilera Arreola explained that the analysis of the samples aims to determine how resistant or how sensitive the bacteria are to treatments. Gonorrhea has been recognized as a public health problem worldwide for several years, but in the last decade, new strains resistant to all antibiotics used against gonorrhea have been reported in some regions of the world, raising fears that they may already be circulating in Mexico. “So far, based on the information we have gathered, it appears that these strains have not yet reached the country, although we still have three months of analysis remaining,” she noted.

“Gonorrhea infections are treated with two antibiotics, ceftriaxone and azithromycin, which are the recommended initial treatment when a doctor suspects an infection of this type,” she said.

The Polytechnic researcher has already identified strains of Neisseria gonorrhoeae resistant to these two antibiotics have already been identified, raising concerns about the importance of monitoring not only the frequency and presence of these infections, but also how they respond to the treatments offered to patients.

The Polytechnic specialist said that in addition to generating this information for patients and doctors, studying gonorrhea from an epidemiological perspective aims to generate data consistent with international guidelines, to contribute our country’s data to international epidemiological surveillance systems, since there is currently no data from Mexico in these systems.

“We want this information to be included in these international databases; we want it to be our contribution to Mexico’s epidemiology. To that end, we sequence the bacterial genome using Multi-Locus Sequence Typing (MLST), a molecular method that allows us to generate data for recording in international systems. the long-term goal is for this project to provide the world with information on the gonorrhea strains circulating in Mexico,” she noted.

INSIDE THE STUDY

Volunteers were recruited from clinics to have their samples processed microbiologically and to receive their results. Strains of Neisseria gonorrhoeae and other associated pathogens were preserved to record and analyze the results, determine their antimicrobial susceptibility profiles, and standardize a method for these procedures.

As of December 2025, 159 volunteers had been recruited, from whom 430 clinical samples have been processed, including 153 urethral swabs, 131 anal swabs, and 146 throat swabs. In all cases, results were provided to the treating physicians, who in turn communicated them to the volunteers.

The average age of the volunteers is 32 years. The predominant marital status was single. Most participants identify as gay. The average age of sexual debut is 16 years. 113 of the volunteers reported not having used barrier protection during their last sexual encounter. Seven participants reported engaging in commercial sex users and, on average, have five different sexual partners per month. 93 volunteers are living with HIV, and 64 reported being HIV-negative.

Regarding strain resistance, the data show that 92% were resistant to tetracycline, 88% to ciprofloxacin, and 40% to penicillin; a 38% showed decreased susceptibility to azithromycin and 2% to cefixime, ceftriaxone, and cefoxitin; 100% of the isolates were susceptible to spectinomycin and cefotaxime.

MULTIRESISTANT GONORRHEA

Gonorrhea is a bacterium that has evolved alongside humans; that is, humans are its only host—it does not infect any other species. It has resisted every treatment designed to combat it, making it essential to prevent and monitor this infection to ensure timely treatment and prevent complications in patients.

“Treatment must be based on solid evidence, study the strains so that the prescribed antibiotic is the most appropriate and people are cured, and educate them so they do not transmit the infection, because every time they engage in risky sexual activity, they will become infected and can infect others, so this transmission network keeps growing,” explained Aguilera Arreola.

Gonorrhea is a notifiable disease in the weekly bulletin issued by the National Epidemiological Surveillance System (Sinave), published by the Ministry of Health through the General Directorate of Epidemiology (DGE), thus, when gonorrhea is detected, it must be reported, in accordance with Mexican Official Standard NOM-039-SSA2-2014 for the prevention and control of sexually transmitted infections.

Despite decades of research, it has not been possible to develop a vaccine for this disease, nor for syphilis or chlamydia.

“We are interested in studying some genomic characteristics of these bacteria, to understand what causes them to change so much. Even if an immune response is generated against the bacteria, the next time you are infected, it will present differences that hinder the effectiveness of the immune response; this makes it very difficult to find a vaccine,” she explained.

Since the microbiology of sexually transmitted infections requires a high level of specialization, the ENCB trains personnel qualified for this line of research.