Introduction
Vulvovaginitis is a prevalent gynecological condition in girls, characterized by inflammation of the vulva and vagina [1]. The condition presents with a range of symptoms, such as vaginal discharge, pruritus, erythema, and discomfort, significantly impacting the quality of life of both the girls and their caregivers. Notably, up to 44.6% of parents experience anxiety, and 35.0% suffer from depressive symptoms, highlighting the emotional burden associated with this condition [2,3].
In the pediatric population, the vaginal environment undergoes substantial changes influenced by hormonal fluctuations, particularly those of estrogen. Before menarche, the vaginal mucosa is thin and alkaline, providing a different microbial habitat from the estrogenic, glycogen-rich, acidic environment observed after menarche [4]. Consequently, the distribution of microorganisms can be affected by menarcheal status during puberty [1,5].
Furthermore, the distribution of these microorganisms differs based on geographic location and ethnic background. For instance, a study of Korean prepubertal girls revealed a predominance of Streptococcus pyogenes (S. pyogenes) (60%), whereas a study of Ethiopian women reported a high incidence of bacterial vaginosis primarily caused by Enterococcus faecalis and Escherichia coli (E. coli) [6,7]. Other studies have shown that E. coli (20.0%) and S. pyogenes (4.2%) are more common in premenarcheal girls, whereas postmenarcheal girls have a high incidence of Candida albicans (14.5%) [1,8].
Given these variations, our study aimed to investigate the clinical features, microbial findings, and treatment outcomes of vulvovaginitis in girls under 20 years of age at a tertiary center in South Korea. This study focused on patients with underlying diseases, as these individuals may exhibit unique microbial profiles and antimicrobial susceptibilities.
Materials and methods
This study was conducted as a retrospective review of medical records and was approved by the Seoul National University Hospital Institutional Review Board (IRB No. 2405-124-1537). We included patients under 20 years of age who visited our institution between 2014 and 2023 and were clinically suspected of having vulvovaginitis, presenting with symptoms for which vaginal culture was performed. We excluded patients who did not undergo culture, those over 20 years of age at the time of testing, those whose cultures were performed as part of a workup for sexual assault, and pregnant patients.
Data were collected on various variables, including age, menarcheal status, presenting symptoms, underlying diseases, and culture results. Treatment details, including symptomatic treatment and empirical antibiotic administration, were recorded according to the clinician’s judgment. Vaginal swab cultures were obtained by swabbing the vaginal introitus, and specimens were processed according to the institution’s standard microbiological procedures. Specifically, gram staining was performed on swabs, which were inoculated on blood agar, MacConkey agar, and chocolate agar plates and incubated at 35°C in 5% CO2 for up to 48 hours. Organisms, such as Lactobacillus spp., coagulase-negative staphylococci, and viridans streptococci were identified and classified as normal vaginal flora. Further analysis was performed if significant growth of microorganisms, such as Candida spp., group B Streptococcus, or gram-negative rods, was observed. Identification and antibiotic susceptibility testing were performed using the VITEK 2 (bioMérieux, Durham, NC, USA), MicroScan WalkAway (Beckman Coulter, Sacramento, CA, USA), or Phoenix M50 (BD Diagnostics Systems, Sparks, MD, USA), depending on the microorganism.
Because this was a retrospective study, the statistical sample size was not calculated prior to data collection. However, a post-hoc power analysis was conducted to evaluate the ability of the study to detect significant differences between the premenarcheal and postmenarcheal groups. This retrospective study included 195 patients, equally distributed between the premenarcheal and postmenarcheal groups. Based on E. coli isolation rates of 14.2% and 6.6% in a previous study [1], a post-hoc power analysis was performed. The calculated effect size (Cohen’s h=0.260) and a significance level of 0.05 indicated that our sample size provided sufficient power (>80%) to detect significant differences in microbial findings and clinical characteristics between the groups.
For statistical analysis, continuous variables were analyzed using the Mann-Whitney U-test, whereas categorical variables were analyzed using the chi-squared or Fisher’s exact test. The proportion Z-test was performed to analyze the distribution of microorganisms between the two groups. All statistical analyses were performed using SPSS version 24 (IBM, Armonk, NY, USA).
Results
The study included 195 girls with vulvovaginitis, categorized into premenarcheal (n=95) and postmenarcheal (n=100) groups. The clinical characteristics of the patients are presented in Table 1. The median age of the patients was 12 years, while the median age for the premenarcheal group was 5 years (range, 0-16 years) and that for the postmenarcheal group was 16 years (range, 10-20 years) (P<0.01). There was a significant difference in the distribution of comorbidities between the two groups: premenarcheal patients more frequently had endocrine (7.4%), neuromuscular (6.3%), and genitourinary (6.3%) diseases, whereas postmenarcheal patients were more likely to have psychiatric (14.0%), malignant (12.0%), and endocrine (10.0%) diseases. The underlying disease states also differed significantly, with a higher proportion of postmenarcheal patients undergoing active treatment (51.0% vs. 30.5%; P<0.01). Recurrence rates did not differ significantly between the groups (P=0.167). The median follow-up period for the entire cohort was 2.23 months, with no significant differences between the two groups (P=0.28). Vaginal swab culture results showed no significant differences between the premenarcheal and postmenarcheal groups, with no growth observed in 11.6% vs. 8.0%, normal vaginal flora in 34.7% vs. 43.0%, and microorganisms identified in 53.7% vs. 49.0% (P=0.43). When potentially pathogenic microorganisms were cultured, gram-negative bacteria were more frequently identified in the premenarcheal group (61.9% vs. 45.5%; P=0.02), whereas Candida species were more common in the postmenarcheal group (9.5% vs. 23.6%, P=0.01) (Fig. 1). Among the potentially pathogenic microorganisms, a single dominant pathogen was identified in 37.5% of cases, two dominant pathogens in 9.7%, and three in 2.1%.
The initial symptoms are shown in Table 2. The most common complaints among all participants were vaginal discharge (63.1%) and pruritus (17.4%). Vaginal discharge was notably more prevalent in the postmenarcheal group (57.9% vs. 68.0%; P<0.01). In addition to vaginal discharge and pruritus, lower abdominal pain (20.0%) was common in the premenarcheal group. By contrast, vulvodynia (4.0%), dysuria (4.0%), and erythema (4.0%) were more frequently observed in the postmenarcheal group.
Supplementary Table 1 summarizes the gram staining results of vaginal discharge samples. Premenarcheal patients had lower proportions of white blood cells (33.8% vs. 41.0%; P=0.03) and epithelial cells (43.2% vs. 78.0%; P<0.01). Gram-positive cocci were more frequently found in premenarcheal samples (33.7% vs. 20.0%; P=0.03), whereas gram-positive rods were more common in postmenarcheal samples (60.0% vs. 25.3%; P<0.01).
The microbial pathogens identified during sample cultivation are summarized in Table 3. Among the 195 patients, Candida species were found in 9.7% of cases, with Candida albicans (C. albicans) being the most common (7.7%). Gram-positive cocci were identified in 14.4% of samples, with Streptococcus agalactiae (group B) found only in the postmenarcheal group (7.0%) and Staphylococcus aureus found only in the premenarcheal group (5.0%). Gram-negative rods were the most frequently identified pathogens, present in 32.8% of all cases, and were significantly more common in the premenarcheal group (37.1% vs. 25.0%; P=0.01). Among these, E. coli was the predominant pathogen, identified in 17.9% of cases. Gardnerella vaginalis was found in 1.5% of cases in the postmenarcheal group, although this difference was not statistically significant (P=0.13). Corynebacterium species were found in 2.1% of cases, with no significant difference between the premenarcheal and postmenarcheal groups (P=0.48).
The antimicrobial susceptibilities of pathogenic gram-positive and gram-negative microorganisms varied significantly (Table 4). Clindamycin and vancomycin were highly effective, with susceptibilities of 94.7% and 100.0%, respectively. By contrast, tetracycline, penicillin, and oxacillin showed lower susceptibilities. Streptococcus agalactiae (S. agalactiae) was 100.0% susceptible to penicillin, clindamycin, and vancomycin but only 57.1% susceptible to tetracycline. Staphylococcus epidermidis showed high susceptibility to clindamycin (85.7%), vancomycin (100.0%), tetracycline (71.4%), and oxacillin (71.4%) but lower susceptibility to penicillin (28.6%). Staphylococcus aureus was fully susceptible to clindamycin, vancomycin, and tetracycline (100.0%) but less susceptible to penicillin (20.0%) and oxacillin (40.0%). Among the gram-negative microorganisms, susceptibilities to amoxicillin/clavulanic acid and piperacillin/tazobactam were 89.3% and 87.9%, respectively. Ciprofloxacin, gentamicin, and nitrofurantoin exhibited susceptibilities of 85.3%, 96.4%, and 100.0%, respectively. Ceftriaxone had a low susceptibility rate (76.0%). E. coli, the most common pathogen, showed high susceptibility to gentamicin (95.0%) and nitrofurantoin (100.0%) and moderate susceptibility to ceftriaxone (76.0%). Klebsiella pneumoniae was 100.0% susceptible to gentamicin and nitrofurantoin. Enterococcus faecalis (E. faecalis) was 100% susceptible to amoxicillin/clavulanic acid, ciprofloxacin, and nitrofurantoin. Nitrofurantoin and gentamicin were the most effective agents against gram-negative bacteria, whereas ceftriaxone was the least effective. Resistance to antifungal agents was not observed in any of the strains.
Among the 64 gram-negative strains identified, 11 (17.2%) were extended-spectrum beta-lactamase (ESBL)-positive microorganisms. Specifically, ESBL-positive strains were identified in six of 35 E. coli strains (17.1%), one of 13 E. faecalis strains (7.7%), and two of eight Klebsiella pneumoniae (K. pneumoniae) strains (25.0%).
The treatment methods applied for vulvovaginitis in the study population are summarized in Supplementary Table 2. Observation was the most common approach, used in 56.4% of cases, with no significant difference between the premenarcheal and postmenarcheal groups (60.0% vs. 53.0%; P=0.40). Antiseptics, such as betadine sitz baths, were used significantly more frequently in premenarcheal patients than that in postmenarcheal patients (44.2% vs. 17.0%; P<0.01). Topical antibiotic ointments were more frequently used in premenarcheal patients (13.7% vs. 4.0%; P=0.03). The use of systemic antimicrobials was not significantly different between the groups (15.8% vs. 27.0%; P=0.08). However, specific antibiotics, such as nitroimidazoles (metronidazole), were exclusively used in postmenarcheal patients (0.0% vs. 11.0%; P<0.01), and tetracyclines (doxycycline) were used only in postmenarcheal patients (0.0% vs. 7.0%; P=0.03). Antifungal treatments were more commonly administered to postmenarcheal patients (20.0% vs. 6.3%; P=0.01), with clotrimazole being the most frequently used (16.0% vs. 6.3%; P=0.01). Fluconazole was used exclusively in postmenarcheal patients (0.0% vs. 4.0%; P=0.01).
Discussion
Our study aimed to evaluate the microbial findings and clinical characteristics of vulvovaginitis in girls, distinguishing between the premenarcheal and postmenarcheal groups. The key findings included a higher prevalence of gram-negative rods in the premenarcheal group and more frequent identification of Candida species in the postmenarcheal group. Vaginal discharge was the most common presenting symptom and was significantly more prevalent in the postmenarcheal group. E. coli was identified as the predominant pathogen, with notable differences in comorbidities and treatment approaches between the two groups. Additionally, by providing antimicrobial susceptibility results for this population, our study offers valuable insights into clinical scenarios requiring empirical antimicrobial treatment in outpatient settings.
1. Clinical presentation and symptoms
The most common presenting symptom was vaginal discharge, reported in 63.1% of cases, consistent with prior study results [1,3,9]. Girls often experience symptoms, such as vaginal discharge, lower abdominal pain, and vulvar erythema. Younger girls may struggle to accurately describe their symptoms, causing significant distress for both patients and their parents [2]. Therefore, conducting a detailed questionnaire and an appropriate physical examination for girls in this age group is crucial [10,11].
The distribution of comorbidities varied significantly between the groups, with premenarcheal patients more likely to have endocrine, neuromuscular, and genitourinary diseases, whereas postmenarcheal patients had higher rates of psychiatric, malignant, and endocrine diseases. This finding aligns with previous studies. The significant prevalence of psychiatric disorders in postmenarcheal patients highlights the psychological impact of menarche and potential need for integrated care approaches [12-14].
Previous studies have attempted to predict pathogenesis based on several clinical factors, such as clinical presentation, previous gynecologic history, contraceptive use, and microscopic findings [15,16]. However, we found no significant predictive model for pathogen identification in our study, suggesting that future evaluations in larger, well-designed prospective cohorts may be necessary.
2. Microbiological findings
The diversity of microbial profiles associated with vulvovaginitis has been noted in various studies, emphasizing the importance of age-specific considerations. Ranđelović et al. [8] and Bumbulienė et al. [17] observed that prepubertal girls often harbor fecal-origin bacteria, consistent with our finding of a higher prevalence of E. coli in premenarcheal patients. This is well known, as younger children have a shorter anatomical distance between the vaginal orifice and anus, creating a more favorable environment for fecal flora migration. Additionally, as puberty progresses, estrogen secretion in the vaginal wall alters the microbiome, promoting the establishment of normal vaginal flora, such as Lactobacillus, while inhibiting the growth of gram-negative bacteria, including E. coli [4,18,19].
Candida species were more common in postmenarcheal girls than in premenarcheal girls, likely because of estrogen secretion into the vaginal wall. Estrogen has been shown to help C. albicans evade the immune system by inhibiting the alternative complement pathway and opsonophagocytosis [20]. Estrogen enhances C. albicans virulence by promoting its adherence to vaginal epithelial cells and evasion of the immune response. Increased levels of 17-β estradiol, whether due to pregnancy or hormonal therapy, can elevate the risk of yeast infections by influencing fungal gene expression and cell wall formation [21,22].
Another important finding was the higher frequency of Candida species in premenarcheal patients in our study compared to that in previous reports, which have documented incidences ranging from 1.5% to 1.9% [1,9]. This discrepancy is likely due to the high proportion of immunocompromised patients with opportunistic infections in our tertiary center cohort [23,24].
Among the gram-positive cocci in our study, S. agalactiae was the most commonly identified, corroborating findings from previous research. Yilmaz et al. [5] highlighted that vulvovaginitis is the most common gynecological problem in childhood, with group A beta-hemolytic Streptococcus frequently isolated in prepubertal girls. A study conducted in Korea by Kim et al. [6] found that S. pyogenes was the leading cause of specific vulvovaginitis in prepubertal girls, with seasonal peaks in summer and winter. Although we did not specifically assess seasonal variations, these findings underscore the importance of considering local epidemiological trends. Although uncommon, the presence of Haemophilus influenzae (H. influenzae) in premenarcheal patients in our study is noteworthy. H. influenzae is primarily associated with respiratory infections; however, previous studies have reported its involvement in vaginitis, potentially linked to concurrent respiratory infections [1,25,26]. Although our patients who were positive for H. influenzae did not have concurrent respiratory infections, this pathogen should be considered clinically significant in the differential diagnosis of vulvovaginitis.
3. Antimicrobial susceptibility and treatment approaches
In terms of antimicrobial susceptibility, our study highlights significant variations in the effectiveness of antibiotics against pathogenic gram-positive and gram-negative microorganisms that cause vulvovaginitis in pediatric patients. Clindamycin and vancomycin were highly effective against gram-positive bacteria, with susceptibilities of 94.7% and 100.0%, respectively, whereas tetracycline, penicillin, and oxacillin showed lower susceptibilities of 73.7%, 58.8%, and 58.3%, respectively. Comparatively, Yasin et al. [7] reported high susceptibility of gram-positive bacteria to vancomycin, cefoxitin, ciprofloxacin, clindamycin, and gentamicin and of gram-negative bacteria to ciprofloxacin, gentamicin, and meropenem. Gao et al. [27] studied children with vulvovaginitis in China and found S. pyogenes to be highly susceptible to penicillin G (100.0%), ceftriaxone (100.0%), and vancomycin (100.0%), whereas H. influenzae exhibited notable resistance to ampicillin (40.5%). Wang and Song [28] reported high resistance rates to itraconazole and fluconazole among fungi, along with multidrug resistance among bacteria. Hu et al. [29] found similarly high susceptibility of S. pyogenes to penicillin (100.0%) and moderate susceptibility of H. influenzae to ampicillin (53.7%).
Given the high prevalence of ESBL-producing strains in our hospital (17.2% overall, with E. coli at 17.1% and K. pneumoniae at 25.0%), careful selection of antibiotics is crucial. For the initial empirical treatment of vulvovaginitis in girls, especially when hygiene education and symptom management have failed, antibiotics, such as gentamicin and nitrofurantoin, for gram-negative infections and clindamycin or vancomycin for gram-positive infections should be considered because of their high susceptibility rates. Therefore, targeted antibiotic therapy based on susceptibility testing is recommended for patients with persistent symptoms and confirmed bacterial infections. Specifically, third-generation cephalosporins can be considered for empirical treatment; however, local resistance patterns and individual susceptibility results should guide the final selection.
Treatment methods varied significantly between the groups in our study. Antiseptics, such as betadine sitz baths, were more commonly used in premenarcheal patients, reflecting recommendations for managing nonspecific vulvovaginitis in younger children through improved hygiene and local antiseptics. Tartaglia et al. [30] supported the use of topical treatments as a first-line approach in prepubertal girls, demonstrating comparable effectiveness to systemic treatments. Systemic antimicrobials and antifungal treatments were more frequently administered in postmenarcheal patients, underscoring the need for targeted antibiotic therapy and antifungal treatments in older children with specific infections. Notably, fluconazole was used exclusively in postmenarcheal patients in our study, likely reflecting challenges in dosage calculations and safety concerns in younger children, leading to a preference for topical treatments in premenarcheal cases. Intravenous vancomycin often requires hospitalization and should be reserved for severe or refractory vulvovaginitis caused by resistant pathogens. Alternative oral or topical treatments may be preferred in milder cases. This finding highlights the need for age-specific antifungal and antibacterial management strategies based on safety profiles and ease of administration. Yilmaz et al. [5] also emphasized the importance of differentiating treatment approaches between prepubertal and pubertal girls owing to differences in etiopathogenesis and microbial profiles. These comparisons reinforce the necessity of age-specific diagnostic and treatment strategies for managing vulvovaginitis.
4. Challenges in caregiver reporting of symptoms
Young girls may have difficulty articulating their experiences, leading to potential underreporting or misinterpretation of symptoms. Furthermore, caregivers may lack awareness of normal versus abnormal genital health in prepubertal girls, potentially overlooking subtle changes or misattributing symptoms [31-33]. This limitation is particularly relevant given that our study cohort included children as young as 5 years old, highlighting the need for tailored clinical approaches. Healthcare providers should prioritize educating both caregivers and children on proper hygiene, normal anatomy, and what constitutes concerning symptoms. Regular health visits that include discussions about genital health can help establish open communication and improve the accuracy of symptom reporting. Additionally, clinicians should consider employing age-appropriate assessment tools and engaging in direct communication with children whenever feasible to supplement caregiver reports. By implementing these strategies, the accuracy of symptom reporting can be enhanced, ultimately improving the diagnosis and management of pediatric vulvovaginitis.
5. Clinical Implications
Significant differences in microbial findings and clinical characteristics underscore the need for tailored diagnostic and therapeutic strategies. Emphasizing hygiene education, particularly in premenarcheal girls, and specific antifungal treatment in postmenarcheal girls may improve management outcomes. Hygiene education, including proper wiping from front to back after toileting, is critical for premenarcheal patients to prevent fecal contamination, a major risk factor for vulvovaginitis in this age group. The high prevalence of E. coli in premenarcheal patients suggests that this bacterium may either be part of the normal flora or result from fecal contamination, highlighting the importance of targeted hygiene education. Similarly, the higher detection of Candida species in postmenarcheal girls may be associated with the use of sanitary pads during menstruation, suggesting a potential area for further investigation.
While previous studies have used the terms “prepubertal” and “postpubertal”, this study focused on “premenarcheal” and “postmenarcheal” groups based on menarcheal status. The rationale for this decision was that factors, such as sanitary pad use after menarche, may influence the risk and characteristics of vulvovaginitis. Furthermore, menarche is a distinct and measurable event, whereas puberty encompasses broader developmental changes and clinical factors that may confound the analyses. Although we referred to prepubertal and postpubertal groups when comparing our results with those of previous studies, the menarcheal-based framework was consistently applied to our analyses and reporting.
This retrospective study has several limitations, including potential bias and a small sample size, which limit generalizability. The lack of detailed information on sexual activity and the variability in sample collection methods may have influenced the results. Treatment approaches varied according to the clinician’s judgment, with no standardized protocols. Additionally, the study was limited to patients who underwent vaginal swab cultures and lacked data on parasites or urine cultures. As this study was conducted at a tertiary hospital, the higher prevalence of underlying diseases and specific antimicrobial susceptibility patterns may not be fully generalizable to primary and secondary care settings. Future largescale prospective studies are needed to validate these findings and refine management guidelines, ultimately improving patient outcomes in pediatric and adolescent gynecology.
In conclusion, this study provides valuable insights into the microbial findings and clinical characteristics of vulvovaginitis in girls, distinguishing between the premenarcheal and postmenarcheal groups and emphasizing the need for tailored diagnostic and therapeutic strategies. Hygiene education is crucial for premenarcheal patients, whereas targeted antifungal treatments are essential for postmenarcheal and selected premenarcheal patients at tertiary centers. Given the high prevalence of ESBL-producing strains, the careful selection of antibiotics based on local susceptibility patterns is necessary.
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