Severe deep neck space infection caused by Eggerthia catenaformis

Abstract

A 64-year-old woman was acutely referred to the Department of Otorhinolaryngology, Head and Neck Surgery, Aalborg University Hospital due to rapidly progressing neck swelling, fever and dysphagia. Clinical examination revealed submental swelling, trismus and laryngeal inflammation. A contrast-enhanced CT scan showed infection in the deep neck spaces with multiple abscesses. The patient underwent acute surgery and antimicrobial therapy was initiated and she was transferred to an intensive care unit. Three additional surgical procedures were needed before sufficient drainage was achieved. There was growth of different oral commensals from four separate pus aspirates, while Eggerthia catenaformis was cultured in all samples. Due to the extent of the infection, the patient stayed in the intensive care unit for 16 days, but recovered completely due to adequate surgery and antimicrobial therapy for 4 weeks. Here we present the third reported case of a severe deep neck space infection with multiple abscesses due to E. catenaformis.

Background

Deep neck space infections (DNSI) are severe infections with potentially life-threatening complications, including airway obstruction and sepsis.^{1 2} They typically arise from the teeth or tonsils, and rarer from the salivary glands and cervical lymph nodes.³

The deep neck spaces are potential spaces between the superficial fascia and the three layers of the deep cervical fascia.⁴ All deep neck spaces communicate, forming pathways by which infections may spread. Infections in the parapharyngeal space are the most common, whereas involvement of the retropharyngeal and visceral spaces is more rare.⁵

Treatment of DNSI usually comprises surgical drainage and antibiotic therapy. DNSI is usually polymicrobial, including representatives from the oropharyngeal microbiota including obligate anaerobes, and mixed infection seems to increase pathogenicity through synergistic interaction between micro-organisms. However, the pathogenic nature of the oropharyngeal microbiota has not been fully clarified.⁶

Eggerthia catenaformis (formerly known as Lactobacillus catenaformis) is a non-spore-forming anaerobic Gram-positive bacillus that can be found in human gastrointestinal microbiota, first described by Eggerth⁷ in 1935 and later reclassified to the genus Eggerthia by Salvetti et al⁸ in 2011. Only six cases of infection caused by E. catenaformis have been reported in the literature, including two with severe neck infections with a suspected odontogenic origin.^9–14 Here we present the third reported case of a severe DNSI with multiple abscesses due to E. catenaformis.

Case presentation

A 64-year-old woman with a history of Crohn’s disease with multiple bowel resections and ileostomy, type B aortic dissection, osteoporosis, and Horton’s disease was acutely referred to the Department of Otorhinolaryngology, Head and Neck Surgery, Aalborg University Hospital. Her symptoms had started 4 days earlier with neck swelling, dysphagia and otalgia and had progressed rapidly within hours prior to referral.

On arrival she presented trismus and submental swelling, but no signs of respiratory distress, stridor or hoarseness. Flexible fibreoptic nasopharyngolaryngoscopy revealed inflammation and swelling of the epiglottis.

Her temperature was 38.1°C and her vital parameters were normal. Total leucocyte count was 13.7×10⁹/L and C reactive protein was 303 mg/L.

Investigations

Acute contrast-enhanced CT (CECT) scan showed accumulations of fluid in the right palatine tonsil, communicating with a cavity in the epiglottis and further into the epiglottic vallecula (figure 1). In addition, there was periapical radiolucency in the lower third molars, indicating a possible site of infection. The diagnosis was DNSI with multiple abscesses.

Figure 1.

First contrast-enhanced CT scan performed on the day of admission. Axial (A), sagittal (B) and coronal (C) views show radiographic signs of an abscess in the right palatine tonsil (A, blue arrow), with connection to an epiglottic abscess (B, blue arrow) and the epiglottic vallecula (C, blue arrows).

Pus from the right tonsillar mucosa obtained at primary surgery was sent to the Department of Clinical Microbiology. Aerobic culture showed growth of commensals not identified further. On the anaerobic plate (chocolate agar with vitamin K and cysteine; SSI Diagnostica A/S, Hillerød, Denmark) there was growth of Gram-positive bacilli and Gram-negatives after 48 hours in an anaerobic chamber (80% n₂, 10% co₂ And 10% h₂; Anoxomat, MART Microbiology, Lichtenvoorde, The Netherlands) at 35°C. Using MALDI Biotyper (Bruker Daltonics, Bremen, Germany), the anaerobic isolates were identified as E. catenaformis and Dialister pneumosintes, with log scores of 2.1 and 2.2, respectively. Furthermore, E. catenaformis was consecutively isolated from all three abscess aspirates obtained during additional surgery on day 3 (two samples) and day 5 (one sample). Gemella species, Alloprevotella species and Candida dubliniensis were also reported in two of four, one of four and one of four samples, respectively. In the last sample, E. catenaformis was the only bacteria cultured, even though the sample was obtained after 5 days of cefuroxime and metronidazole. E. catenaformis was reported sensitive to both penicillin (minimum inhibitory concentration (MIC): 0.004 mg/L) and metronidazole (MIC: 0.25 mg/L). A standard blood culture set (two bottles, BD BACTEC Plus Aerobic Medium; one bottle, BD BACTEC Lytic Anaerobic Medium) obtained before initiation of antibiotic therapy and two additional sets on days 2 and 5 during antibiotic therapy remained culture-negative after a 7-day incubation period.

Treatment

On admission, the patient was administered empiric intravenous cefuroxime 1.5 g every 8 hours, metronidazole 500 mg every 8 hours and dexamethasone and underwent acute surgery. Direct laryngoscopy revealed a ruptured abscess cavity on the epiglottis, likely perforated during the intubation procedure. Due to suspected tonsillar and odontogenic focus, bilateral tonsillectomy and extraction of the lower third molars were performed. However, there were no perioperative signs of a peritonsillar or dental abscess, which contradicted the CECT findings. The patient remained intubated postoperatively and was transferred to the intensive care unit (ICU).

On day 3, the patient developed swelling in the left submental region and along the left sternocleidomastoid muscle. Acute CECT scan showed accumulations of gas in the epiglottis, vallecula, right palatine tonsil area and retropharyngeally on the left side, as well as fluid under the left-side infrahyoid muscles (figure 2). She underwent additional surgery, with external drainage through an incision anteriorly to the sternocleidomastoid muscle, confirming an abscess formed under the infrahyoid muscles. During direct laryngoscopy an additional abscess cavity on the left side of the hypopharynx was identified, punctured and internally drained.

Figure 2.

Second contrast-enhanced CT scan performed on day 3. Axial (A, B) and sagittal (C) views show accumulation of gas (blue arrows) and fluid under the left-side infrahyoid muscles (orange arrows).

On day 5, the patient’s condition again deteriorated with renewed swelling of the left neck area. The third acute CECT scan showed signs of persistent inflammation, gas and accumulated fluid in the former affected areas and additionally in the left palatine tonsil region and in the left posterior cervical space (figure 3). During surgery, pus in the mucosa of the left palatine tonsil area was observed. Additional external drainage was performed through an incision laterally to the hyoid bone on the left side, revealing an abscess communicating with the submandibular and submental space.

Figure 3.

Third contrast-enhanced CT scan performed on day 5. Axial (A) and sagittal (B) views show persistent accumulation of gas (blue arrows) as well as inflammation and signs of fluid in the submental and submandibular spaces (orange arrows).

On day 7, cefuroxime was changed to piperacillin/tazobactam 4.5 g every 6 hours in combination with clindamycin 600 mg every 8 hours and metronidazole for another 14 days. On day 8, additional submental swelling occurred and a new CECT scan showed signs of remaining abscess cavities in the retropharyngeal, parapharyngeal, submental and both peritonsillar regions, as well as under the deep cervical fascia. No pus was observed during the following exploratory surgery, but a tracheostomy was performed due to sustained swelling of the larynx.

On day 16, the patient was discharged from the ICU and decannulated on day 19. On day 21, she was able to eat and had no difficulty breathing. Her blood parameters normalised and she was discharged with oral metronidazole for an additional 2 days.

Outcome and follow-up

At follow-up on day 24 the patient had almost recovered except for fatigue and light stiffness of the neck. Flexible fibreoptic nasopharyngolaryngoscopy showed slight redness in the mucosa and swelling of the aryepiglottic and vestibular folds.

On day 31, she contacted the department due to a sensation of swelling in the throat. Examinations showed no signs of recurrence, but due to history with severe DNSI she was prescribed 7 days of oral penicillin V and metronidazole.

At follow-up 6 weeks after initial admission she was continuously improving, and at 12 weeks only slight stiffness of the neck and odynophagia remained and clinical examinations were unremarkable.

Discussion

Our case is only the sixth case describing an infection caused by E. catenaformis. Two other cases of DNSI caused by E. catenaformis have been documented, both with an odontogenic focus, but none with the same extent of space involvement.^{11 12} During a total of four surgical procedures, abscess formation was identified in the visceral, retropharyngeal, submandibular and submental spaces, as well as an epiglottal abscess and near universal phlegmon of the pharyngeal mucosa. The exact site of the origin remained uncertain in this case as the palatine tonsils did not show signs of inflammation and no peritonsillar abscess was found during bilateral tonsillectomy. Furthermore, there were no signs of dental abscesses during tooth extractions. It could have been an infected epiglottic or vallecular cyst, but the patient did not report any symptoms to substantiate this. In adults, the most frequent sites are pharyngeal and odontogenic infections, but Boscolo-Rizzo et al¹⁵ found that the pathogenesis remained undocumented in 18.9% of cases with deep neck infections.

Preoperative CECT scans were used in order to evaluate the extent of the infection and to plan surgery, but a discrepancy between preoperative imaging and surgical findings was found. The positive predictive value of CECT in DNSI is high (80%–82%), but there are limitations regarding its ability to distinguish phlegmon and abscess.^{16 17} As this case demonstrates, imaging should never stand alone and must be accompanied by clinical and paraclinical evaluations.

Bacteraemia is usually considered a severe complication and has been described in five out of the six previous E. catenaformis cases.^9–14 Our case had no positive blood culture; however, E. catenaformis was consecutively cultured from all four pus aspirates obtained during the primary and revisional surgery. The last aspirate was culture-positive after 5 days of antibiotic therapy and hence the bacteria was considered the predominant pathogen.

Genomic analysis of E. catenaformis has identified genes related to virulence and genes that encode resistance to tetracycline and aminoglycosides.¹⁸ For many Gram-positive anaerobic bacteria, including Lactobacillus species, susceptibility to ampicillin, amoxicillin and piperacillin can be inferred from susceptibility to benzylpenicillin according to the European Committee on Antimicrobial Susceptibility Testing.¹⁹ Our isolate of E. catenaformis had low MIC for penicillin as well as metronidazole. Still, E. catenaformis was cultivated as the sole bacteria in the last pus sample despite 5 days of cefuroxime and metronidazole therapy. Susceptibility testing to cephalosporins, including cefuroxime, was not performed, but for invasive Lactobacillus species variable susceptibility to cephalosporins has been reported.²⁰

In the previous cases E. catenaformis was usually reported as sensitive to penicillin, amoxicillin, piperacillin/tazobactam, clindamycin, metronidazole, meropenem and vancomycin; however, there is no accepted treatment regimen.^9–13 In this case, the initial regimen was cefuroxime and metronidazole, but was later changed to a broad-spectrum regimen of piperacillin/tazobactam, clindamycin and metronidazole for 14 days to provide maximum antibacterial coverage even though E. catenaformis alone was sensitive to penicillin and metronidazole. In selected ICU patients, antibiotic de-escalation and targeted antibiotic treatment may be appropriate following antimicrobial susceptibility testing, but because the patient had abscesses in multiple deep neck spaces de-escalation was not an option.

In conclusion, our findings substantiate that E. catenaformis should be considered an emerging pathogen especially in mixed infections like DNSI. The patient was successfully treated by a team composed of otorhinolaryngologists, odontologists, clinical microbiologists and intensive care physicians, highlighting the importance of multidisciplinary assessment in DNSI as well as adequate antibiotic treatment.

Learning points.

• Eggerthia catenaformis is an emerging human pathogen especially in mixed infections of oral origin.

• Deep neck space infection (DNSI) is a rare but severe complication of head and neck infections in adults and should be identified quickly as the condition can rapidly progress and become life-threatening.

• Treatment of DNSI should be multidisciplinary to ensure surgical drainage, appropriate antimicrobial therapy and intensive care if needed.

• Contrast-enhanced CT may have limitations in evaluating DNSI and should be accompanied by clinical examination and laboratory testing.