Evaluating the Antibiotic Resistance Patterns in Mycoplasma hominis and Ureaplasma spp. Infections in Salvador, Brazil

Abstract

Background/Objectives: Mycoplasma and Ureaplasma species are pathogens commonly associated with urogenital infections in sexually active individuals. Despite their clinical relevance, these organisms are less frequently studied than other sexually transmitted infections (STIs), leading to limited data on their antimicrobial susceptibility and resistance profiles. This study aimed to characterize the antimicrobial susceptibility and resistance patterns of Mycoplasma hominis and Ureaplasma spp. among individuals in Salvador, Bahia, Brazil, and to identify the potential associated risk factors. Methods: We conducted a retrospective descriptive study during 2022–2024 using secondary data obtained from the SMARTLab^® diagnostic system. Sociodemographic and epidemiological data, along with results from IST2 and IST3 diagnostic tests, were analyzed. Absolute and relative frequencies were calculated by sex, age group, and antimicrobial susceptibility profile. Results: Our results revealed a predominance of M. hominis and Ureaplasma spp. infection among women (98.5%), and in individuals aged 38 to 47 years. Ureaplasma spp. accounted for the majority of positive cases. High rates of resistance were observed in the IST2 test, with 75.0% of M. hominis and 84.1% of Ureaplasma urealyticum resistant to ciprofloxacin. In the IST3 test, Ureaplasma spp. demonstrated a 7.3% resistance rate to levofloxacin, which increased to 22.2% in cases of co-infection. Conclusions: These findings underscore the growing threat of antimicrobial resistance in Mycoplasma and Ureaplasma species and highlight the need for targeted public health strategies and diagnostic tools to manage infections caused by these organisms, particularly in high-risk populations.

1. Introduction

Mycoplasma and Ureaplasma, commonly referred to as “Mycoplasmas,” are prokaryotic pathogens classified within the phylum Tenericutes, class Mollicutes. These microorganisms are characterized by their lack of a cell wall, which confers resistance to traditional Gram staining methods and contributes to their pleomorphic morphology. Additionally, their low metabolic rate and rapid replication capabilities are notable features [1,2]. The plasma membrane of mycoplasma and ureaplasma species contains sterols, specific lipids that increase membrane stability and enhance resistance to osmotic lysis compared to other bacterial groups [1,3]. The two genera differ primarily in ureaplasma’s ability to produce the urease enzyme, which catalyzes the breakdown of urea into ammonia and carbon dioxide, thus alkalinizing the surrounding environment [4].

The bacteria Mycoplasma hominis, Ureaplasma urealyticum, and Ureaplasma parvum are significant pathogens within the group of sexually transmitted infections (STIs), capable of affecting the urogenital tract in sexually active individuals [2]. When symptomatic, these bacteria can cause a range of infections, including prostatitis, bacterial vaginosis, cervicitis, pelvic inflammatory disease (PID), and even infertility in both men and women [1,5]. Although Ureaplasma spp. can be sexually transmitted, they are not always considered true STI pathogens due to their relatively low pathogenicity and the frequent colonization of asymptomatic individuals [4,6]. In particular, U. urealyticum has been more consistently associated with symptomatic infections and adverse reproductive outcomes, whereas U. parvum, although more commonly isolated, is generally considered less virulent, and its clinical relevance remains a matter of debate [4,6].

These infections may occur as mono- or co-infections involving Mycoplasma, Ureaplasma, and other sexually transmitted pathogens, complicating both clinical diagnosis and management. It has been shown that high sexual activity, multiple sexual partners, younger age, female gender, inconsistent condom use, and a history of previous STIs are associated with an increased likelihood of mycoplasma and ureaplasma exposure and infection. Furthermore, these infections are associated with adverse pregnancy outcomes such as preterm birth, premature rupture of membranes, low birth weight, and neonatal or perinatal death [2,5,6].

The World Health Organization (WHO) estimates that more than one million new cases of curable STIs are acquired every day globally, with many of these infections being asymptomatic [7]. Common clinical symptoms associated with mycoplasma infections include dysuria, genital discharge, and dyspareunia. However, these symptoms are not exclusive to mycoplasmas and overlap with other STIs, making a specific diagnosis challenging [2,8]. Moreover, the slow growth of these microorganisms in conventional culture media hinders the characterization of their epidemiological profiles, particularly in diverse regions such as Brazil [5].

The lack of standardized laboratory protocols for diagnosing M. hominis and Ureaplasma spp. further complicates species-specific treatment guidelines, where antibiotics recommended for other STIs are often used [5]. This lack of targeted therapy has contributed to the growing ineffectiveness of treatment options, representing a significant global health challenge [9]. In fact, antimicrobial resistance in mycoplasma and ureaplasma species has been recognized as a critical issue, with resistance to multiple antibiotic classes becoming increasingly common, and the WHO has identified antimicrobial resistance as a priority public health threat, urging the development of new therapeutic strategies [10,11].

Resistance to antibiotics, particularly within specific classes, has been increasingly documented [12]. Strains of Mycoplasma genitalium and Ureaplasma spp. exhibiting resistance to macrolides, tetracyclines, and fluoroquinolones, including azithromycin, levofloxacin, and moxifloxacin, have been reported [9]. These pathogens are sensitive to antibiotics that target protein and DNA/RNA synthesis, metabolism, or cell membrane integrity, including tetracyclines, macrolides, ketolides, lincosamides, and fluoroquinolones [13,14]. Despite the significant impact of M. hominis and Ureaplasma spp. On infertility and reproductive health, these organisms remain under-studied in many regions, including Brazil, when compared to other STIs [5]. Furthermore, the antimicrobial susceptibility profiles of M. hominis and Ureaplasma spp. in Brazil remain poorly explored, with resistance patterns varying across different regions of the country. This variability further complicates the development of effective treatment strategies and highlights the need for more localized research.

Here, we aimed to assess the antimicrobial susceptibility profiles of M. hominis and Ureaplasma spp. in individuals tested at a private laboratory in Salvador, Bahia. This study also explores the epidemiological characteristics of patients, including the prevalence of mycoplasma and ureaplasma species, and provides an in-depth analysis of the susceptibility profiles of positive cultures.

2. Materials and Methods

2.1. Study Design and Data Collection

A descriptive retrospective study was conducted using secondary data collected from the SMARTLab^® system database from a private laboratory in Salvador, the capital of Bahia State (which has an estimated population of 2.5 million for 2024). During March 2022–2024, a total of 8611 mycoplasma tests were performed, and individuals ≥ 18 years old who tested positive in culture were included, while individuals with incomplete or unclear records were excluded from the study. Epidemiological data such as age, gender, and mycoplasma culture results (e.g., microorganisms’ identification and susceptibility profile) were collected. Data were stored electronically via REDCap version 14.1.2 (Research Electronic Data Capture) [15].

2.2. Antimicrobial Susceptibility Testing

The Mycoplasma IST2 diagnostic test (BioMérieux, France) was initially used to identify and quantify Mycoplasma hominis and Ureaplasma urealyticum, and to test susceptibility to nine antibiotics, including doxycycline, josamycin, ofloxacin, erythromycin, tetracycline, ciprofloxacin, azithromycin, clarithromycin, and pristinamycin. The IST2 assay is based on interpretive criteria provided by the manufacturer and does not follow internationally standardized breakpoints [8,14]. The IST2 test determines susceptibility through a colorimetric change based on pH variation, indicating bacterial growth or inhibition at predefined antibiotic concentrations, with internal growth controls included to validate the results.

The Mycoplasma IST3 (BioMérieux, Marcy-l’Étoile, France) test has been introduced to additionally identify Ureaplasma parvum and test susceptibility to six antibiotics separately for each species: levofloxacin, moxifloxacin, tetracycline, and clindamycin for Mycoplasma hominis; and moxifloxacin, tetracycline, erythromycin, telithromycin, and levofloxacin for Ureaplasma spp. Unlike IST2, the IST3 assay follows the Clinical and Laboratory Standards Institute (CLSI) guidelines, which define standardized breakpoints for the antimicrobial susceptibility testing of human mycoplasmas [8,14]. This study compares data from the year before and after the implementation of IST3.

2.3. Statistical Analysis

Relative and absolute frequency were calculated by sex, age groups (18–27, 28–37, 48–57, 58–67, and 68–77 years old), mycoplasma culture (IST2 versus IST3 test), and antibiotic susceptibility profile. All data were analyzed using the RStudio version 4.5.1 (Posit PBC) statistical analysis system.

3. Results

3.1. Demographic Characteristics of the Studied Population

A total of 8611 individuals were included in the study, in which 819 (9.5%) tested positive for Mycoplasma hominis and/or Ureaplasma spp. The age distribution of the participants revealed that the majority were between 28 and 47 years old, with 33.21% aged 28–37 years and 37.36% aged 38–47 years. Notably, nearly 40% of the positive test results were observed in individuals within the 38–47 years of age group. Younger adults, aged 18–27 years, accounted for 16% of the total sample, while those older than 58 years represented only 3.4%. Most participants were female (n = 808, 98.7%) (

Table 1. Sociodemographic characteristics of the 819 selected positive culture cases in a private laboratory in Salvador, Brazil (2022–2024).

Characteristics	Positive Test n (%)
Gender
Female	808 (98.7%)
Male	11 (1.3%)
Age group
18–27	131 (16%)
28–37	272 (33.2%)
38–47	306 (37.4%)
48–57	82 (10.0%)
58–67	19 (2.3%)
68–77	9 (1.1%)

).

The most common sample type was endocervical swabs, which accounted for 393 (48.0%) of the cases, followed by vaginal secretion samples at 337 (41.2%). Cervical secretion and cervix samples represented 41 (5.0%) and 32 (3.9%) of the cases, respectively. Less frequent sample types included first-catch urine (n = 10, 1.2%), urethral secretion (n = 5, 0.6%), and anal secretion (n = 1; 0.1%) (

Table 2. Distribution of the 819 sample types among the collected specimens for Mycoplasma and Ureaplasma detection in a private laboratory in Salvador, Brazil (2022–2024).

Sample Type	n (%)
Endocervix	393 (48%)
Vaginal secretion	337 (41.2%)
Cervical secretion	41 (5.0%)
Cervix	32 (3.9%)
First-catch urine	10 (1.2%)
Urethral secretion	5 (0.6%)
Anal secretion	1 (0.1%)
Total	819 (100%)

).

Among the 819 positive cases, Ureaplasma spp. was detected in 656 individuals (80.0%), while Mycoplasma hominis was identified only in 31 cases (4.0%). Additionally, 132 individuals (16.0%) presented with a co-infection, testing positive for both Ureaplasma spp. and Mycoplasma hominis (Figure 1).

3.2. IST2 Test

A total of 454 individuals were tested using the Mycoplasma IST2 test. Of these, 361 (79.5%) tested positive only for Ureaplasma urealyticum, 19 (4.2%) only for Mycoplasma hominis, and 74 (16.3%) for co-infection (

Table 3. Antibiogram for 19 positive cases of Mycoplasma hominis, 361 cases of Ureaplasma urealyticum, and 74 cases of co-infection using the IST2 test (n = 454).

Antibiotics	Only Mycoplasma (n = 19)			Only Ureaplasma (n = 361)			Mycoplasma and Ureaplasma (n = 74)
	S	I	R	S	I	R	S	I	R
Doxycycline	19 (100%)	0	0	359 (99.4%)	1 (0.3%)	1 (0.3%)	73 (98.6%)	1 (1.4%)	0
Josamycin	19 (100%)	0	0	359 (99.4%)	2 (0.6%)	0	73 (98.6%)	1 (1.4%)	0
Ofloxacin	11 (57.9%)	0	8 (42.1%)	103 (28.5%)	24 (6.7%)	234 (64.8%)	12 (16.2%)	3 (4.1%)	59 (79.7%)
Erythromycin	7 (36.8%)	1 (5.3%)	11 (57.9%)	335 (92.8%)	14 (3.9%)	12 (3.3%)	5 (6.7%)	16 (21.6%)	53 (71.7%)
Tetracycline	19 (100%)	0	0	358 (99.2%)	1 (0.3%)	2 (0.5%)	72 (97.3%)	2 (2.7%)	0
Ciprofloxacin	10 (52.6%)	0	9 (47.4%)	53 (14.8%)	10 (2.8%)	298 (82.5%)	3 (4.1%)	3 (4.1%)	68 (91.8%)
Azithromycin	6 (31.6%)	2 (10.5%)	11 (57.9%)	315 (87.3%)	25 (6.9%)	21 (5.8%)	6 (8.1%)	15 (20.3%)	53 (71.6%)
Clarithromycin	7 (36.9%)	2 (10.5%)	10 (52.6%)	343 (95%)	7 (1.9%)	11 (3.1%)	8 (10.8%)	15 (20.3%)	51 (68.9%)
Pristinamycin	18 (94.7%)	0	1 (5.3%)	359 (99.4%)	1 (0.3%)	1 (0.3%)	72 (97.2%)	1 (1.4%)	1 (1.4%)

).

Among the 19 individuals who tested positive only for Mycoplasma hominis, azithromycin exhibited 10.5% intermediate susceptibility and 57.9% resistance, erythromycin had 5.3% intermediate and 57.9% resistance, and clarithromycin showed 52.6% resistance, thereby underscoring their poor reliability and limited effectiveness in treatment. Ciprofloxacin showed 47.4% resistance, while ofloxacin exhibited 42.0%, indicating limited efficacy of both antibiotics. In contrast, doxycycline, josamycin, tetracycline, and pristinamycin all demonstrated 100% susceptibility with no intermediate or resistant cases reported (Table 3).

Of the 361 individuals who tested positive for Ureaplasma urealyticum, doxycycline, tetracycline, and pristinamycin demonstrated 99.4% susceptibility, indicating high efficacy. Josamycin also showed high effectiveness with 99.4% susceptibility and 0.6% intermediate response. Clarithromycin had 95% susceptibility and 3.1% resistance. Erythromycin and azithromycin exhibited high susceptibility at 92.8% and 87.3%, respectively, though erythromycin had 3.9% intermediate and 3.3% resistance, and azithromycin had 6.9% intermediate and 5.8% resistance. Ofloxacin exhibited a high resistance rate of 64.8%, while ciprofloxacin showed limited efficacy, with 14.7% susceptibility, 2.8% intermediate, and 82.5% resistance, making it unsuitable for Ureaplasma urealyticum treatment (Table 3).

The 74 individuals who tested positive for both Ureaplasma urealyticum and Mycoplasma hominis demonstrated a more resistant profile to the antibiotics. Ciprofloxacin demonstrated low efficacy with 91.9% resistance, followed by ofloxacin with 79.6% resistance, and erythromycin with 71.6%. Azithromycin showed 8% susceptibility, 20.3% intermediate, and 71.6% resistance. Clarithromycin demonstrated 10.8% susceptibility, 20.3% intermediate, and 68.9% resistance. Meanwhile, doxycycline and josamycin remained highly effective with 98.6% susceptibility. Pristinamycin showed 97.3% susceptibility and only 1.4% intermediate response, and tetracycline exhibited 97.3% susceptibility and 2.7% intermediate response, indicating strong efficacy (Table 3).

3.3. Legend: S: Sensitive; I: Intermediate; R: Resistant; Absence of Interpretation Criteria. IST3 Test

A total of 365 individuals (44.6%) out of the 819 individuals selected for this study tested positive through the Mycoplasma IST3 test. Among these, 80.8% (295/365) tested positive for Ureaplasma spp. only, 3.3% (12/365) for Mycoplasma hominis only, and 15.9% (58/365) were co-infected with both species (

Table 4. Antibiogram results for 12 positive cases of Mycoplasma hominis, 295 cases of Ureaplasma spp., and 58 cases of co-infection with Ureaplasma urealyticum and Mycoplasma hominis as evaluated by the IST3 test.

Antibiotics	Only Mycoplasma (n = 12)			Only Ureaplasma (n = 295)
	S	I	R	S	I	R
Levofloxacin	12 (100%)	0	0	267 (90.5%)	6 (2%)	22 (7.5%)
Moxifloxacin	12 (100%)	0	0	289 (98%)	5 (1.7%)	1 (0.3%)
Tetracycline	12 (100%)	0	0	278 (94.2%)	7 (2.4%)	10 (3.4%)
Clindamycin	12 (100%)	0	0	-	-	-
Erythromycin	-	-	-	294 (99.7%)	1 (0.3%)	0
Telithromycin	-	-	-	293 (99.3%)	0	2 (0.7%)
Co-infection (n = 58)
Levofloxacin	55 (94.8%)	1 (1.7%)	2 (3.5%)	50 (86.2%)	1 (1.7%)	7 (12.1%)
Moxifloxacin	54 (93.1%)	0	4 (6.89%)	53 (91.4%)	1 (1.7%)	4 (6.9%)
Tetracycline	56 (96.6%)	1 (1.7%)	1 (1.7%)	53 (91.4%)	1 (1.7%)	4 (6.9%)
Clindamycin	52 (89.7%)	0	6 (10.3%)	-	-	-
Erythromycin	-	-	-	56 (96.6%)	0	2 (3.4%)
Telithromycin	-	-	-	54 (93.1%)	0	4 (6.9%)

Legend: S: sensitive; I: intermediate; R: resistant; Absence of interpretation criteria. Mycoplasma hominis antibiogram results to tetracycline, levofloxacin, moxifloxacin, and clindamycin. Ureaplasma spp. antibiogram results to tetracycline, levofloxacin, moxifloxacin, erythromycin, and telithromycin. For the co-infection cases, Mycoplasma hominis antibiogram with tetracycline, levofloxacin, moxifloxacin, and clindamycin, while Ureaplasma urealyticum with tetracycline, levofloxacin, moxifloxacin, erythromycin, and telithromycin.

). No significant resistance to any antibiotics tested was observed for individuals who tested positive solely for Mycoplasma hominis (Table 4).

Regarding the 80.8% (295/365) individuals who tested positive only for Ureaplasma spp. using the IST3 test, these individuals exhibited an effectiveness with 99.7% susceptibility and no cases of resistance to erythromycin, and telithromycin showed 99.3% susceptibility. Moxifloxacin demonstrated a very high susceptibility of 98%, with 1.7% intermediate response and 0.3% resistance. Tetracycline achieved 94.2% susceptibility, with 2.4% intermediate and 3.4% resistance. Levofloxacin showed effectiveness with 90.5% susceptibility, though resistance was present in 7.5% of cases and 2% were intermediate, suggesting it is largely effective but not without limitations (Table 4).

Among the 58 individuals (15.9%) who tested positive for both Ureaplasma spp. and Mycoplasma hominis using the IST3 test, the susceptibility results were analyzed separately for each pathogen. Mycoplasma hominis achieved complete susceptibility for tetracycline and a high susceptibility rate of 94.8% for levofloxacin, with 1.7% intermediate and 3.4% resistance. Moxifloxacin exhibited 93.1% susceptibility with 6.9% resistance. Clindamycin showed a lower susceptibility rate of 89.7%, with 10.3% resistance, suggesting it may be less reliable for Mycoplasma infections compared to other options. For Ureaplasma spp., erythromycin achieved 96.6% susceptibility, with 3.4% resistance. Moxifloxacin, tetracycline, and telithromycin each demonstrated 91.4% susceptibility and 6.9% resistance. Levofloxacin showed moderate effectiveness against Ureaplasma, with 86.2% susceptibility, 1.7% intermediate response, and 12.1% resistance (Table 4).

4. Discussion

Mycoplasma hominis and Ureaplasma spp. are microorganisms that colonize the urogenital tract of sexually active adults and are implicated in opportunistic infections, particularly in immunocompromised individuals, and the clinical management of these infections is complicated by the variability in antibiotic resistance profiles. In this study, Ureaplasma urealyticum was the most frequently detected pathogen in both the IST2 (79.5%) and IST3 (80.8%) tests. Although Mycoplasma hominis was less commonly detected, it exhibited reduced susceptibility to clindamycin, and its resistance profile to other antibiotics was further exacerbated in co-infection scenarios. Doxycycline, tetracycline, josamycin, and pristinamycin demonstrated high efficacy, while fluoroquinolones (particularly ciprofloxacin and ofloxacin) showed significant resistance rates.

It has already been well-documented that mycoplasma species are exhibiting rising global resistance to commonly used drugs like azithromycin, ciprofloxacin, and ofloxacin [16]. This trend is notable across different regions, with studies in Europe and Asia reporting significant resistance rates to fluoroquinolones, tetracyclines, and macrolides [16]. For instance, Belgium has recorded fluoroquinolone resistance rates as high as 31.3%, with similar patterns observed in Spain, Germany, and other European countries [5,17]. These increasing resistance rates significantly compromise the efficacy of first-line treatments, thereby intensifying the challenge of managing such infections, especially in patients with co-infections or recurrent infections [5,16,17]. Given these challenges, it is crucial to implement comprehensive strategies that focus on both control and prevention, including the rational use of antibiotics. In addition, surveillance programs to monitor resistance trends in these pathogens are fundamental to support public health policies and ensure the effectiveness of treatment guidelines.

In the results presented by the Mycoplasma IST2 test, the highest resistance was observed in Ureaplasma urealyticum to ciprofloxacin and ofloxacin, both of which are second- and third-generation fluoroquinolones, respectively. Similarly, Ureaplasma urealyticum showed 82.5% resistance to ciprofloxacin and 64.8% resistance to ofloxacin, indicating a significant limitation in treatment options for these patients. The resistance to fluoroquinolones observed here could be associated with genetic alterations in DNA gyrase and/or the topoisomerase complex, which are the primary targets of these antibiotics. Such modifications can hinder the antibiotics’ ability to bind effectively to their targets, thereby diminishing their therapeutic action and contributing to treatment failure [9,18]. Furthermore, macrolides, such as erythromycin, azithromycin, and clarithromycin, exhibited a notable level of resistance among Mycoplasma hominis cases. This pattern highlights the growing challenge in managing infections caused by mycoplasma and ureaplasma species, as resistance to first-line treatment options can significantly limit therapeutic efficacy and complicate clinical outcomes.

Individuals who exhibited co-infections showed a marked increase in resistance frequencies, significantly related to ciprofloxacin (91.9%), ofloxacin (79.6%), and 71.6% for both erythromycin and azithromycin. Although erythromycin and other macrolides exhibit notable efficacy, our findings highlight a concerning trend in patients with co-infections [19,20]. The presence of co-infections not only complicates the clinical management of these patients but also contributes to a more pronounced antibiotic resistance profile [19,20].

The frequency of positive cases for Ureaplasma spp. tends to be higher compared to those for Mycoplasma hominis, as observed in both the IST2 and IST3 tests. Among the 3.3% (12/365) of individuals who tested positive solely for Mycoplasma hominis via the IST3 test, none exhibited significant resistance to the antibiotics tested. In contrast, in the IST3 test, Ureaplasma spp. demonstrated a resistance rate of 7.5% and an intermediate response rate of 2% to levofloxacin, a fluoroquinolone. Additionally, resistance to tetracyclines was documented in only Ureaplasma cases at 3.4% and 2.4% intermediate, while in cases of co-infection, resistance was recorded at 6.9%. This is a significant concern considering the drug’s broad-spectrum antibiotic and potent bacteriostatic activity against different pathogens [2].

However, it is important to note that tetracycline resistance in Ureaplasma spp., with and without co-infection, is higher in the IST3 tests. This highlights a crucial issue: the previous IST2 test used an incorrect tetracycline breakpoint for Ureaplasma spp., leading to an underestimation of resistance. The IST2 kit applied a breakpoint of S ≤ 4 µg/mL and R ≥ 8 µg/mL, following CLSI standards for Mycoplasma hominis. However, for Ureaplasma spp., the correct breakpoint is S ≤ 1 µg/mL and R ≥ 2 µg/mL. The IST3 test was updated to reflect this correct breakpoint, ensuring a more accurate assessment of tetracycline resistance in Ureaplasma species [2,12,21].

The comparative analysis between the two diagnostic tests showed an absence of erythromycin resistance when using the IST3 test, which had been frequently noted in the co-infection scenario using the IST2 test. In IST2, erythromycin resistance was often overestimated in mixed cultures; however, in the IST3 test, the ability to test each species independently allowed for more accurate results, revealing that the erythromycin resistance seen in IST2 was largely a result of this methodological limitation [14]. These issues highlight the importance of using updated and validated methods like IST3. Additionally, the intrinsic antibiotic resistance of these organisms heightens the likelihood of failure in empirical treatment strategies for symptomatic urogenital infections [22].

Our results also demonstrated a significant variation in infection rates across age groups. Most cases occurred in individuals aged 38 to 47, accounting for 37.4% of the total (306/819), followed by the 28 to 37 year age group, which made up 33.2% (272/819). These findings suggest that Mycoplasma and Ureaplasma infections are most prevalent among sexually active middle-aged adults. Notably, the highest number of positive cases was observed in the 21–30 and 31–40 age brackets, further indicating a significant prevalence among younger, sexually active populations [23,24,25]. The concentration of cases within these age brackets highlights the importance of targeted public health interventions aimed at these populations, particularly in terms of awareness, prevention, and screening strategies. Further research is warranted to explore the underlying causes of these age-related trends and to develop tailored approaches for managing infections in these high-prevalence groups.

The study’s sociodemographic data also highlights a striking 98.7% (808/819) of the diagnosed patients being women. This finding indicates that Mycoplasma and Ureaplasma infections disproportionately affect females within this population, aligning with existing research [24,25]. The prevalence of Mycoplasma in the genital tract ranges from 5 to 20% in sexually active men and 40–80% in women, and this higher incidence among sexually active women varies by region, country, and even within the same population, depending on ethnicity and socioeconomic status [2,25,26]. Additionally, although Mycoplasma hominis is part of the vaginal microbiota, it can become pathogenic in disturbed vaginal environments, acting opportunistically [6]. Similarly, Ureaplasma urealyticum is also present in the genital microbiota, with many of its infections in women occurring asymptomatically [5].

5. Strengths and Limitations

This study provides relevant microbiological data on Mycoplasma hominis and Ureaplasma spp. infections in adults using a standardized culture-based diagnostic approach and a relatively large sample size collected over a two-year period. To our knowledge, this is one of the few studies in Brazil providing antimicrobial susceptibility data for these pathogens based on local laboratory data.

However, some limitations must be considered. First, the retrospective and single-center design limits the generalizability of the findings to other regions or populations. Second, the study included only individuals with positive cultures, without comparison to negative cases or healthy controls, which limits the ability to explore risk factors or prevalence. Furthermore, the lack of clinical and other epidemiological information, such as symptoms, previous or continuous use of antibiotics, and presence of comorbidities, prevents correlation between microbiological findings and clinical outcomes.

6. Conclusions

The data presented here reveals a complex relationship between antimicrobial resistance and population characteristics. The significant resistance patterns observed among urogenital pathogens, such as mycoplasma and ureaplasma, particularly in female individuals, underscore the urgent need for tailored diagnostic and therapeutic strategies. Resistance profiles vary regionally due to factors such as local antibiotic use and healthcare practices, highlighting the necessity of continuous evaluation through targeted testing. Regular updates to diagnostic methods, such as the transition from IST2 to IST3, are essential to ensure the accurate detection of resistance patterns and to improve treatment efficacy. As resistance continues to evolve, it will be crucial to refine testing methodologies in order to optimize patient outcomes and preserve the effectiveness of the existing antimicrobial agents.

Considering the increased concern regarding antimicrobial resistance among mycoplasma and ureaplasma species, it is essential to adopt comprehensive strategies focused on both control and prevention. This includes the rational use of antibiotics, guided by accurate susceptibility testing whenever possible, and the implementation of antimicrobial stewardship programs. In addition, strengthening STI prevention efforts through sexual education, regular screening (especially for high-risk populations), and partner notification and treatment is crucial to reduce transmission rates. Expanding surveillance programs to monitor resistance trends in these pathogens will also be fundamental to support public health policies and ensure the effectiveness of treatment guidelines.