Tuboovarian abscess due to Eikenella corrodens

Dear Editor,

Pelvic inflammatory disease (PID) is one of the most serious gynaecological infections in non-pregnant women of childbearing age,¹ and can lead to complications such as tubal infertility, ectopic pregnancy, abdominal pain and tubo-ovarian abscess.^1–3Neisseria gonorrhoeae and Chlamydia trachomatis are the most common aetiological agents, with sexual contact being the principal route of transmission.³ The insertion of an intrauterine device (IUD) and invasive gynaecological procedures are significant risk factors, and involve microorganisms from the normal microbiota of the genital tract, primarily species of Streptococcus, Enterococcus, Peptostreptococcus and Bacteroides.^2,3Eikenella corrodens and Finegoldia magna form part of the oropharyngeal, gastrointestinal and genitourinary microbiota, and their involvement in intra-abdominal and gynaecological infections is rare.³ We present the case of a tubo-ovarian abscess caused by E. corrodens and F. magna in a patient with no risk factors.

A 23-year-old woman without an IUD, and with no gynaecological history of interest, was seen for hypogastric pain and abundant vaginal secretions. The examination and transvaginal ultrasound revealed no signs of disease. The patient returned 10 days later due to intense pain and a fever of 38.3 °C. Transvaginal ultrasound was performed and revealed a mass compatible with tubo-ovarian abscess in the retrouterine area. Treatment was initiated with clindamycin, ampicillin and gentamycin, and laparoscopic surgery was performed. During the intervention, the abscess was ruptured, a sample was taken for microbiological cultures and left salpingectomy was performed. During the immediate post-operative period, the patient presented with fever, elevated procalcitonin (2 ng/l), leukocytosis (22.8 × 10³/l) and signs compatible with sepsis, and was admitted to the intensive care unit. Blood cultures were taken, and the antibiotic therapy was switched to piperacillin/tazobactam and doxycycline. Following favourable evolution, the patient was transferred to the gynaecology ward.

With regard to the microbiological study of the abscess, the Gram stain revealed abundant polymorphonuclear leukocytes, gram-negative bacilli and gram-positive cocci. The aerobic culture isolated small greyish colonies that were catalase-negative and oxidase-positive, and produced a slight depression in chocolate agar. Additionally, small greyish colonies were observed in Schaedler agar and phenylethyl alcohol agar after anaerobic incubation. E. corrodens was identified using the Vitek^®2 (bioMérieux) system's NH card, and confirmed by mass spectrometry on the Vitek^® MS system (bioMérieux). F. magna was identified from the API^® rapid ID 32 A gallery (bioMérieux). The antibiogram for both microorganisms was performed using the E-test gradient diffusion assay (bioMérieux) and interpreted based on Clinical and Laboratory Standards Institute (CLSI) criteria. E. corrodens showed resistance to azithromycin and susceptibility to meropenem, ceftriaxone, ciprofloxacin, levofloxacin, tetracycline, ampicillin and amoxicillin/clavulanic acid. The MICs for gentamycin and piperacillin/tazobactam were 6 and <0.016/4 mg/l, respectively (without CLSI interpretation). F. magna showed resistance to metronidazole and susceptibility to meropenem, cefotaxime, clindamycin, penicillin, ampicillin, amoxicillin/clavulanic acid and piperacillin/tazobactam (MIC = 0.032 mg/l). Based on these results, antibiotic therapy with piperacillin/tazobactam was maintained for 10 days. The patient showed favourable evolution, and was asymptomatic at discharge.

The majority of E. corrodens infections are polymicrobial.^4,5 In our case, it was isolated together with F. magna, a combination which was not found in the literature reviewed.

Moreover, gynaecological infections caused by E. corrodens are rare, being associated primarily with PID in women with IUDs^4–6 and chorioamnionitis.⁷ In the case presented, we highlight its role together with F. magna in causing a tubo-ovarian abscess in the absence of risk factors. Antibiotic therapy with clindamycin and gentamycin is one of the empirical treatments recommended by clinical guidelines.^2,8 In our case, ampicillin was added, as this combination has demonstrated good results in the treatment of tubo-ovarian abscesses.⁹ Due to the rupture of the abscess during surgery and appearance of signs of sepsis, treatment was switched to piperacillin/tazobactam, following the recommendations for the management of intra-abdominal infection in high-risk patients.¹⁰ Doxycycline was also added as antibiotic prophylaxis against C. trachomatis. After obtaining the microbiology results, the decision was made not to alter the treatment as the MICs for piperacillin/tazobactam were low for both microorganisms, and the patient showed favourable evolution. Due to the variety of serious infections that E. corrodens can cause and their possible complications, we believe it is important to correctly isolate and identify the microorganism, and to assess its role as a causal agent in obstetric and gynaecological infections.