Recurrent Peritonsillar Abscess Caused by Vaginal Flora: A Common Problem From a Unique Source

Introduction

The microorganism most isolated from peritonsillar abscesses (PTAs) is group A Streptococcus. ¹ Gardnerella vaginalis is a natural anaerobe of the vagina, with overgrowth causing bacterial vaginosis; it is not found in the oropharynx. ² We present a case of recurrent PTA after orogenital sex that failed to improve until G. vaginalis was isolated and antimicrobial coverage was broadened. To our knowledge, this is the first case in the literature of vaginal flora causing a deep space neck infection.

Case Report

Ethics approval by our institution’s Institutional Review Board (IRB) was not required as this is a single case report. A healthy 19-year-old female with sore throat had negative rapid strep and COVID-19 testing. She was started on penicillin but had worsened pain, odynophagia, muffled voice, and fever. She presented to the emergency department, where point of care ultrasound scan demonstrated a left PTA that was aspirated with improvement in symptoms. Cultures were not sent, and penicillin was continued.

Two days later, the patient reported to otolaryngology clinic with worsened symptoms and PTA recurrence on examination, which was incised and drained. Her antibiotic was changed to amoxicillin-clavulanate, with addition of a methylprednisolone taper. Cultures grew oral flora and symptoms improved. Four weeks later, she reported to clinic with a third PTA that was incised and drained and sent for culture, and she restarted amoxicillin-clavulanate and steroids.

Symptoms again improved but worsened 2 days later, with additional dyspnea. In the emergency department, ultrasound and computed tomography (CT) scans demonstrated a 4.5 cm left PTA with reactive lymphadenopathy and mild airway narrowing (Figure 1).

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Figure 1.

Axial CT with measurements demonstrating left 4.5 cm PTA with reactive lymphadenopathy and mild airway narrowing. CT, computed tomography; PTA, peritonsillar abscess.

On the same day as this recurrence, most recent cultures finalized with G. vaginalis. The patient then disclosed that she recently performed oral sex on a female; her partner was reportedly healthy with no abnormal vaginal discharge. The PTA was incised and drained a fourth time and grew oral flora. Amoxicillin-clavulanate and steroids were continued, and metronidazole was added for G. vaginalis coverage.

The patient improved on this regimen and underwent tonsillectomy 6 weeks later, with an inflamed left tonsil and subcentimeter pocket of pus in the subcapsular space; this again grew oral flora. The patient recovered with no complications or recurrent symptoms. A timeline of presentation, interventions, and laboratory findings is found in Figure 2.

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Figure 2.

Timeline summary of interventions, cultures, and antimicrobial treatment.

Discussion

The most isolated pathogen in PTA is group A Streptococcus, although 80% of cultured PTAs are polymicrobial and do not yield a predominant species.^1,3,4 Diagnosis of PTA can often be made by clinical examination, although point of care ultrasound and CT scans can increase diagnostic accuracy and guide procedural interventions.^5-7 Patients are typically treated with antibiotics for streptococcal coverage, with or without any combination of needle aspiration, incision and drainage, and steroids. If a patient has multiple PTAs, tonsillectomy is recommended after infection has resolved.^8-11

The vaginal microbiome is dominated by Lactobacilli species, although it also includes the gram-variable, anaerobic G. vaginalis. Bacterial vaginosis is marked by decline in Lactobacilli and relative increase in G. vaginalis leading to pH imbalance, malodorous discharge, and itching; treatment is with metronidazole.^2,12 The microbiome of the upper aerodigestive tract, while diverse, does not include G. vaginalis.

This patient performed oral sex on a female prior to recurrence of the third PTA, the only culture that grew a dominant bacterium, G. vaginalis. It is therefore presumed that G. vaginalis was transmitted from her partner’s vagina, possibly entering the peritonsillar space through a procedural site to cause superinfection.

This raises the question of possible bacterial transference from genitals to oropharynx during oral sex. Further studies are warranted to investigate how commonly this occurs and what bacteria are transmissible. Providers may consider obtaining a sexual history on patients with oropharyngeal infections and advising patients to temporarily abstain from oral-genital contact after oral procedures.

This case highlights the importance of culturing PTAs to direct antimicrobial therapy in certain patients. Although the rate of positive pus cultures in PTAs is extremely variable and may have limited impact on management, there are specific indications where culture is warranted. ⁹ Evaluation of level 3 evidence has demonstrated the benefit of abscess culture by needle aspiration for patients with recurrent or persistent infection and in those who are diabetic or immunocompromised. ⁹ In this case of recurrent infection unresponsive to incision and drainage with empiric antibiotic coverage, culture of the PTA was warranted to further direct management.

Conclusions

This is a unique case of recurrent PTA caused by superinfection of G. vaginalis after oral-vaginal sex. Further studies are warranted to identify if oral sex is a risk factor for transference of genital bacteria to the upper aerodigestive tract, and if it should be avoided following oral procedures. This case highlights the importance of culturing PTA contents after drainage to best direct antimicrobial therapy in those with recurrent or persistent infection.