STREPTOCOCCUS PYOGENES AS THE CAUSE OF VULVOVAGINITIS IN ADULT WOMEN

According to the literature data, Streptococcus pyogenes is the most common cause of infectious vulvovaginitis in prepubertal girls, but it is rarely described in adult women. In this paper we report the prevalence of S. pyogenes vulvovaginitis in adult women in the municipality of Niš, Serbia, in a five-year period. The total of 42.259 women with symptoms of vulvovaginal infection were enrolled in the study and their swabs from the vagina and cervix were examined using the standard microbiological procedures: direct microscopy of Gram stained preparations and sample culture. Women with positive S. pyogenes findings were later contacted to give anamnestic data and for post-treatment control examinations. S. pyogenes was isolated from the samples of 2 patients: in July 2012 in a 20year-old woman with the anamnesis of a previously diagnosed tonsillopharyngitis, and in May 2015 in a 32-year-old breast-feeding woman. These patients had the signs and symptoms of acute inflammation: vaginal and vulvar pain, dyspareunia, burning sensation, pruritus, and a profuse, watery, yellow vaginal discharge. Gram staining revealed abundant segmented WBCs and gram-positive cocci in pairs and chains. After the administered penicillin therapy, the control microbiological examinations of the vaginal and cervical swabs were done, as well as the throat swab culture for the presence of S.pyogenes, and all the results were negative. Streptococcal vulvovaginitis in adult women was diagnosed in only two examinees in our study and was associated with a predisposing factors: personal history of a respiratory infection and lactational vaginal atrophy. Acta Medica Medianae 2016;55(4):82-85.


Introduction
Streptococcus pyogenes (S. pyogenes) is the most common cause of tonsilopharyngitis but has also been implicated as an etiological agent of perineal infections in children: perianal infections, vulvovaginitis and balanitis (1,2). According to the literature data, S. pyogenes is the most common cause of infectious vulvovaginitis in prepubertal girls (1)(2)(3)(4)(5). In contrast, S. pyogenes vulvova-ginitis is rarely described in adult women (6,7) and is often associated with a predisposing factor: a household or personal history of dermal or respiratory infection due to S. pyogenes, sexual contact, and lactational or menopausal vaginal atrophy (8).
The purpose of this study is to give an overview of the prevalence of S. pyogenes genital infection in adult women with vulvovaginitis symptoms and association of certain risk factors with this form of infection in the municipality of Niš, Serbia.

Methods
The study was done at the Center of Microbiology, Institute of Public Health Niš, in the period from January 1, 2011 to December 31, 2015. The total of 42.259 patients referred to the Center by their gynecologists because of the symptoms of a vulvovaginal infection, were enrolled in the study. The swabs from the vagina and cervix were obtained in our out-patient department and www.medfak.ni.ac.rs/amm examined in the Laboratory for sexually transmitted diseases of the Center of Microbiology. According to the standard procedures, our microbiological examination of the collected samples involved direct microscopy of Gram stained preparations and sample culture on Columbia agar with 5% sheep blood incubated in ambient air and chocolate agar incubated in an atmosphere enriched with 5% of carbon dioxide, at 37°C. The isolates were identified as being S. pyogenes by their colony morphology, β-haemolysis on blood agar plates, bacitracin susceptibility using the Bacitracin Low Diagnostic Tablets (Rosco Diagnostica, Taastrup, Denmark), agglutination with specific group A antisera (Slidex, Streptokit; bio-Merieux, Marcy l'Etoile, France) and The BBL Crystal™ Gram-Positive (GP) Identification System (Becton Dickinson, USA). Kirby-Bauer antimicrobial susceptibility testing was performed by disk diffusion on Müeller-Hinton agar supplemented with 5% defibrinated sheep blood, according to the guidelines of the Clinical and Laboratory Standards Institute (9). Women with positive S. pyogenes findings were later contacted to give anamnestic data and for post-treatment control examinations.

Results
In the five-year study period, S. pyogenes was isolated from samples of 2 patients: in a 20year-old woman in July 2012, and in a 32-year-old woman in May 2015. Patients with this streptococcal infection had the signs and symptoms of acute inflammation: vaginal and vulvar pain, dyspareunia, burning sensation, pruritus, and profuse, watery, yellow vaginal discharge. Gram staining revealed abundant segmented WBCs, gram-positive cocci in pairs and chains, and a notable absence of Lactobacillus-like gram-positive rods. The patient's culture grew S. pyogenes, one resistant to bacitracin. The isolated S. pyogenes strains were sensitive to penicillin and resistant to erythromycin, clindamycin, tetracyclin and quinolones.
It should be mentioned, regarding the association of certain risk factors with this form of infection, that the 20-year-old woman in her anamnesis gave the information of a previously diagnosed tonsillopharyngitis. The second patient, a 32-year-old woman was 6 months postpartum breast-feeding and was experiencing lactational amenorrhea. After the administered penicillin therapy, good outcomes of the disease were observed in both patients considering the fact that S. pyogenes was not isolated in control microbiological examinations of the vaginal and cervical swabs, as well as the throat swab culture, and patients were without symptoms of vulvovaginitis.

Discussion
In adult women, S. pyogenes vaginal carrier state has been described, but vulvovaginitis is rarely reported (10). In their case-control study, Bruins et al. investigated the association between non-group B β-haemolytic streptococci and vulvovaginitis in adult women and S. pyogenes was isolated in 4.9% of women with recurrent vaginal discharge, but none from the controls (5). Mead et al. found that a vaginal-rectal colonization rate with S. pyogenes in late pregnancy was a rare event (0.03%) (11).
S. pyogenes vulvovaginitis in adult women is often associated with a household or personal history of dermal or respiratory infection due to S. pyogenes. The carriage or exposure to a carrier is an important pathogenic factor in recurrent S. pyogenes infection (7). Sobel et al. reported 2 cases of recurrent streptococcal vulvovaginitis in which the gastrointestinal tracts of the patients' husbands were colonized with S. pyogenes (10). Verkaeren et al. described a patient whose husband was found to be an asymptomatic carrier, after S. pyogenes was identified in nasal and rectal swabs (6). Meltzer et al. reported that the patient's husband had been ill with an upper respiratory tract infection at the time of sexual contact (7). This case appears to be somewhat unusual, because S. pyogenes genital infection was sexually transmitted. These cases reiterate the necessity for an adequate screening of the patient's family and contacts in cases of recurrent S. pyogenes infection by culturing the material from all areas potentially infected with S. pyogenes.
Low estrogen levels in postmenopausal and postpartum women increase the susceptibility of vaginal mucosa to infection. A decrease in Lactobacillus species, and an increase in vaginal pH are  (7,13,15). In our study, S. pyogenes vulvovaginitis was associated with a predisposing factor: personal history of respiratory infection and lactational vaginal atrophy.
Clinically, streptococcal vulvovaginitis is characterized by the signs and symptoms of an acute infection: burning sensation, painful erythematous vulva and vagina, dyspareunia with profuse, watery, yellow and occasionally serosanguineous vaginal discharge (7,8). In our study, both examinees with S. pyogenes infection had a clinically manifest inflammatory reaction and Gram staining revealed large numbers of segmented WBCs. Sensitivity to bacitracin is routinely used in the preliminary identification of S. pyogenes, but some resistant strains have been described in several countries. In Portugal, Friães et al. reported a resistance to bacitracin in 5% of S. pyogenes strains (16). In our study, one strain was resistant to bacitracin which should be borne in mind in routine microbiological identification of S. pyogenes strains.
The drug of choice in the therapy of noncomplicated S. pyogenes infections is oral peni-cillin for 10-14 days or 2% clindamycin cream per vaginam for 7-10 days. A possible resistance of S. pyogenes strains to macrolides should also be considered, since macrolides are used as an alternative in the therapy of streptococcal infections. In our study, a resistance to erythromycin was found in both isolates, expressing cMLSB resistance. In the cases of marked vaginal atrophy, as may be seen postpartum in breastfeeding women or in postmenopausal women, the treatment with local estriol cream or ovules may be necessary to prevent the recurrence of S. pyogenes vulvovaginitis (8,12,13). Antibiotic prophylaxis including rifampin and amoxicillin was demonstrated to be efficient in eradicating pharyngeal carriage of S. pyogenes (6).
Based on the results of this study, a conclusion may be drawn that S. pyogenes vulvovaginitis in adult women is very rare and associated with a predisposing factor: personal history of respiratory infection and lactational vaginal atrophy. Nevertheless, due to the severity of clinical signs and symptoms and possible relapses, these infections deserve special attention of gynecologists. Mandatory microbiological examinations are therefore recommended, as well as their close follow-up all the way to the complete cure, and health education work.