Early recurrent peritonsillar abscess associated with Gardnerella vaginalis following oral sex: A case report

Abstract

Introduction

Peritonsillar abscess (PTA) is usually caused by common oropharyngeal microorganisms. Gardnerella vaginalis, which is primarily associated with bacterial vaginosis, is rarely implicated in oropharyngeal or deep neck infections.

Case presentation

An otherwise healthy 18-year-old man developed a left PTA that resolved after incision and drainage, 5 days of intravenous ampicillin/sulbactam, and subsequent oral antimicrobial therapy. Initial abscess culture yielded only normal oral flora. Eight days after discharge, he engaged in oral sex with a female partner. Four days later, PTA recurred at the same site. G. vaginalis was the predominant organism recovered from the recurrent abscess and was identified by MALDI-TOF MS. The patient improved after repeat drainage and empiric re-initiation of ampicillin/sulbactam, which was continued without modification.

Conclusion

G. vaginalis may be associated with early recurrent PTA after oral sexual exposure, although direct transmission cannot be established. Unexpected organisms and relevant exposure histories should be considered in patients with unusually early or atypical PTA recurrence.

Introduction

Peritonsillar abscess (PTA) is a common deep neck infection that usually develops as a complication of acute tonsillitis. Its microbiology is typically polymicrobial, with frequently implicated organisms including Streptococcus pyogenes, members of the Streptococcus anginosus group, Fusobacterium species, and other aerobic and anaerobic oropharyngeal bacteria [1].

Gardnerella vaginalis is a gram-variable, facultative anaerobic coccobacillus best known for its association with bacterial vaginosis. It may also be detected at extra genital sites, including the oral cavity [2], but its role as a pathogen in oropharyngeal or deep neck infections is rarely reported.

We describe an early recurrent PTA in an otherwise healthy young man in whom G. vaginalis was isolated from the recurrent abscess after recent oral sexual exposure. The case highlights the value of appropriate microbiological assessment and a detailed exposure history when PTA recurs unusually early after apparently successful treatment.

Case presentation

An 18-year-old previously healthy man presented to our otolaryngology clinic with a 3-day history of severe and progressively worsening left-sided sore throat, odynophagia, and mild trismus. He had no relevant medical history, recent dental procedures, or clinical findings suggestive of immunodeficiency.

Oral and flexible endoscopic examinations demonstrated marked swelling of the left peritonsillar region with mild deviation of the uvula to the right. The overlying soft-palatal mucosa showed inflammatory erythema (Fig. 1A). A diagnosis of left PTA was made. Contrast-enhanced computed tomography at the initial presentation demonstrated a localized abscess in the left peritonsillar space without extension into the deeper neck spaces (Fig. 2A). Needle aspiration followed by incision and drainage evacuated highly viscous white purulent material. The patient was admitted and intravenous ampicillin/sulbactam 12 g/day was started empirically. His symptoms and local swelling improved promptly. He completed 5 days of intravenous therapy and was discharged asymptomatic with an additional 7-day course of oral amoxicillin/clavulanate (250/125 mg three times daily) plus amoxicillin (250 mg three times daily).

Fig. 1.

Pharyngeal findings during the initial and recurrent episodes. (A) Initial episode showing swelling of the left peritonsillar region with inflammatory mucosal erythema. (B) Recurrent episode at the same site showing more extensive soft-palatal edema and more intense mucosal erythema.

Fig. 2.

Contrast-enhanced computed tomography of the neck during the initial and recurrent episodes. (A) Initial episode showing a localized fluid collection with peripheral enhancement in the left peritonsillar space. (B) Recurrent episode showing a fluid collection at a similar location. In both episodes, the abscess was confined to the peritonsillar space without extension into the parapharyngeal or retropharyngeal spaces.

Culture of purulent material obtained during the initial episode yielded only normal oral flora under aerobic and anaerobic culture conditions, with no dominant pathogen identified. On the initial admission, the white blood cell (WBC) count was 16,000/µL and C-reactive protein (CRP) was 1.30 mg/dL.

Eight days after discharge, the patient engaged in sexual activity that included oral sex with a female partner. According to the patient, his partner had no known history of or symptoms suggestive of bacterial vaginosis at the time of sexual contact. At a scheduled outpatient visit 10 days after discharge, he remained asymptomatic and pharyngeal examination showed complete resolution of the previous inflammatory findings. Two days later, however, left-sided sore throat rapidly recurred. He was readmitted the following day, 13 days after the initial discharge.

On readmission, marked edema of the left peritonsillar region extended into the soft palate, with more intense mucosal erythema than during the initial episode (Fig. 1B). The WBC count was 18,000/µL and CRP was 5.95 mg/dL. Repeat incision and drainage at the same site yielded malodorous purulent material. Repeat contrast-enhanced computed tomography demonstrated a localized left peritonsillar abscess without extension into the parapharyngeal or retropharyngeal spaces and without evidence of internal jugular vein thrombosis (Fig. 2B).

To further evaluate for concurrent infectious diseases, serologic testing was performed for human immunodeficiency virus (HIV), syphilis, hepatitis B virus, and hepatitis C virus. HIV testing, rapid plasma reagin (RPR), Treponema pallidum antibody, hepatitis B surface antigen (HBsAg), and hepatitis C virus antibody were negative.

Aerobic culture yielded only scant normal oral flora, whereas anaerobic culture showed predominant growth of G. vaginalis, with only minimal background oral flora. Given its predominance in the abscess specimen, G. vaginalis was considered the most likely pathogen. Species identification was performed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Antimicrobial susceptibility testing was not performed for the G. vaginalis isolate.

Intravenous ampicillin/sulbactam 12 g/day was restarted empirically immediately after repeat drainage, before the culture identification result was available. After G. vaginalis was identified, the antimicrobial regimen was continued without modification because the patient showed a favorable clinical response. Local edema, erythema, sore throat, and odynophagia resolved over the subsequent 5 days, and inflammatory markers returned to the reference range. The patient was discharged asymptomatic. Approximately 1 month after the initial episode, tonsillectomy was performed. No recurrence of PTA was observed during the 3 months after tonsillectomy.

Discussion

This case describes an unusually early recurrence of PTA in which G. vaginalis was isolated from the recurrent abscess. Reports implicating G. vaginalis in pharyngeal or deep neck infections are scarce. Barguil et al. reported a pharyngeal abscess complicated by Lemierre syndrome in which G. vaginalis and Fusobacterium necrophorum were isolated following recent oral sexual exposure [3]. Landeen et al. reported recurrent PTA after oral-genital contact, in which G. vaginalis was identified after repeated recurrences and antimicrobial coverage was subsequently broadened [4]. Other genital tract-associated organisms have also rarely been reported in PTA. Morioka et al. described PTA following oral sex in which Mycoplasma hominis and F. necrophorum were isolated [5], Waldmeyer et al. reported PTA following sexual intercourse in which M. hominis was identified as the sole pathogen [6], and Yamagishi et al. reported PTA caused by Prevotella bivia [7].

In contrast to the case reported by Barguil et al., our patient had a localized PTA without extension into the deeper neck spaces or internal jugular vein thrombosis. In contrast to the case reported by Landeen et al., our patient improved without modification of the empirically restarted ampicillin/sulbactam regimen after identification of G. vaginalis. Furthermore, our patient had documented clinical resolution of the initial PTA before the unusually early recurrence.

In the present patient, the initial PTA appeared to have resolved clinically after drainage and antimicrobial treatment. Importantly, he was asymptomatic and had normal pharyngeal findings at follow-up before the recurrent episode. Although incomplete eradication of the initial infection cannot be entirely excluded, the combination of adequate drainage, continued oral antimicrobial therapy after discharge, and documented clinical resolution before recurrence makes simple treatment failure less likely. The recurrence occurred at the same site shortly thereafter, and G. vaginalis was the predominant organism recovered from the recurrent abscess. These observations support a possible role for G. vaginalis in the recurrent infection. However, they do not establish the route of acquisition or prove direct transmission from the patient's sexual partner.

The temporal relationship with oral sex is clinically noteworthy but should be interpreted cautiously. Although the partner reportedly had no known history or symptoms suggestive of bacterial vaginosis, she was not clinically or microbiologically evaluated, and no strain-level comparison was performed. In addition, G. vaginalis has been detected in the oral cavity [2]. Therefore, the present findings demonstrate an association between recent oral sexual exposure, isolation of G. vaginalis, and early recurrent PTA, rather than a proven transmission event.

Another notable feature is that the recurrent infection responded to the same antimicrobial regimen used during the initial episode. Ampicillin/sulbactam was selected empirically at recurrence, before organism identification was available, and was continued without modification. Antimicrobial susceptibility testing was not performed for the G. vaginalis isolate; therefore, the in vitro susceptibility of the isolate to ampicillin/sulbactam could not be confirmed. Thus, clinical improvement was achieved without culture-directed modification of antimicrobial therapy.

The recurrent episode was associated with more extensive mucosal erythema and edema and higher systemic inflammatory markers than the initial episode. Whether this reflected pathogen-specific inflammatory effects, the local tissue environment, or undetected co-pathogens cannot be determined. Culture-based testing also cannot exclude organisms that were not recovered under the conditions used.

The main strength of this report is the documented clinical resolution between the two episodes together with microbiological identification of an unusual organism at recurrence. Its principal limitations are the absence of clinical and microbiological evaluation of the sexual partner, lack of strain-level comparison, absence of antimicrobial susceptibility testing for the G. vaginalis isolate, and the inability of a single case to establish causality or a transmission route. Because microbiological assessment during the initial episode relied on conventional culture alone, the possibility that G. vaginalis was already present but not recovered cannot be excluded; molecular analyses such as species-specific PCR or 16S rRNA sequencing were not performed. Tonsillectomy was performed approximately 1 month after the initial episode, and no further PTA occurred during 3 months of postoperative follow-up; therefore, the natural risk of further recurrence without tonsillectomy cannot be assessed. Nevertheless, the case suggests that unexpected organisms should be considered when PTA recurs unusually early after apparently successful treatment, and that a detailed exposure history, including recent sexual contact when clinically appropriate, may guide microbiological investigation.

Conclusion

Gardnerella vaginalis was isolated from an early recurrent peritonsillar abscess in an otherwise healthy young man in temporal association with recent oral sexual exposure. Although direct sexual transmission could not be established, the case illustrates that organisms outside the usual oropharyngeal flora may be associated with atypical or early recurrent PTA. Repeat microbiological evaluation and a detailed exposure history should be considered when the clinical course is unusual.

CRediT authorship contribution statement

Yoichiro Ota: Writing – review & editing, Writing – original draft, Visualization, Investigation, Data curation, Conceptualization. Rumi Sekine: Writing – review & editing, Investigation. Matsusato Tsuyumu: Writing – review & editing, Investigation. Kyoko Chujo: Writing – review & editing, Supervision.

Ethics declaration

This study was performed in compliance with relevant laws, regulatory frameworks and guidelines where the research took place. Ethics committee approval was not required under relevant laws and institutional guidelines. Ethical approval was not required for this single-patient case report in accordance with the institutional policy of St. Luke’s International Hospital.

This research follows the CARE guidelines and the CARE checklist.

Written informed consent to take part in the study and to publish the article has been obtained from all participants or their legal representatives. The privacy rights of participants have been observed.

Declaration of Generative AI and AI-Assisted Technologies in the Manuscript Preparation Process

During the preparation of this work, the authors used ChatGPT to assist with translation and improve the language and readability of the manuscript. The authors reviewed and edited the content as needed and take full responsibility for the content of the publication.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Data availability

Data sharing is not applicable to this article because no datasets were generated or analyzed beyond the clinical information presented in this case report.