Abstract

Background: Citrobacter koseri, a Gram-negative organism, rarely causes an epidural spinal abscess.

Case Description: A 50-year-old male presented with mild paraparesis attributed to an magnetic resonance (MR)-documented spinal epidural abscess (SEA) at the T10-level. Following surgical debridement, cultures grew C. koseri, a rare Gram-negative organism. The abscess was subsequently managed with a prolonged course of antibiotics resulting in complete symptom and MR-documented radiological resolution.

Conclusion: A 50-year-old male presented with a T10 SEA attributed to a rare Gram-negative organism, C. koseri. The abscess was appropriately managed with surgical decompression/debridement, followed by prolonged antibiotic therapy.

Keywords: Antimicrobial treatment, Citrobacter koseri, Epidural spinal abscesses, Laminectomy, Spinal infection

INTRODUCTION

A 50-year-old male presented with a mild thoracic paraparesis attributed to an magnetic resonance (MR)-documented T10 epidural abscess. At surgery, the pathology proved to be a rate Gram-negative organism, Citrobacter koseri.[ 14 ] Following a decompressive laminectomy with abscess debridement and prolonged postoperative antibiotic therapy, the patients symptoms resolved along with the radiographic findings.

CASE DESCRIPTION

Presentation and first operative course

A 50-year-old male with hypertension and diabetes presented with thoracic pain of 4 months duration, and the acute onset of a T10-level paraparesis. The MR documented epidural cord compression at the T10-T11 (compressing cord to the left) and T11-T12 (compressing the cord to the right) levels [ Figures 1a - c ]. The T10-T11 laminectomy performed under neurophysiological intraoperative monitoring revealed a partially calcified lesion compressing the cord; intraoperatively, after the cord was decompressed, the somatosensory potentials significantly improved. The intraoperative frozen section revealed leucocyte infiltration and calcification of the lesion, but initial postoperative cultures were negative. Therefore, the patient was routinely discharged without a diagnosis of infection.

Figure 1:

Preoperative studies, sagittal magnetic resonance imaging. (a and b) T1-weighted and T2-weighted show an epidural hypointense image of triangular appearance (arrow) at the anatomical site of the yellow ligaments at the T10 vertebral level that molds to the dura mater and compresses posterior and lateral left cords. (c) T1-weighted post contrast does not enhance with the contrast material; it is introduced to the left intervertebral foramen (arrow).

Return 7 days later with infection diagnosed as C. koseri

The patient returned 7 days later with a wound infection; once reopened, a brown discharge was cultured. Broad-spectrum antibiotics (AB) (i.e., Ertapenem and Vancomycin) were immediately started; 5 days after the second surgery, cultures from both the first and second surgeries were documented in a rare Gram-negative organism, C. koseri. Within 8 postoperative days, the peripheral white blood cell count and acute phase reactants normalized; then continued, Ciprofloxacin for an additional 2 weeks, along with 4 days of Ertapenem. Six months later, the thoracic magnetic resonance imaging showed complete resolution of the epidural abscess/ wound infection, and the patient fully recovered [ Figure 2 ].

Figure 2:

Post-operative studies, sagittal magnetic resonance imaging. (a and b) T1-weighted and T2-weighted show a left laminotomy with hemostatic material to the surgical site injected slightly into the dura mater (arrow). The medullary cord recovers its caliber, currently without mass effect.

DISCUSSION

Risk factors for spinal epidural abscesses (SEAs) due to C. koseri

Citrobacter is a nonsporulating, facultatively anaerobic, and Gram-negative bacteria of the Enterobacteriaceae family that was first isolated in 1932 by Werkman and Gillen.[ 5 , 15 ] It is frequently found in mammals’ water, soil, food, and intestines.[ 13 ] These infections can occur in the urinary tract (39%), gastrointestinal system (27%), wound/decubitus ulcers (10%), pulmonary, or other sites (11%). Although they typically occur in patients with diabetes mellitus, intravenous drug use, or compromised hosts (i.e., patients over >60 years of age and neonates), other cases have been reported in younger patients without clear risk factors.[ 2 , 6 , 7 , 9 , 12 , 14 ]

Treatment of choice for SEA due to C. koseri

The treatment of choice for epidural spinal abscesses in patients with significant neurological deficits is often operative decompression (i.e., laminectomy)/aggressive operative debridement, followed by 4–16 weeks of postoperative intravenous AB.[ 7 , 14 ] While some infections may resolve by the 4^th postoperative week, others will require total treatment durations of six or more weeks [ Table 1 ].[ 6 , 9 , 10 , 12 ] Notably, symptoms and inflammatory markers can help guide the efficacy and duration of antibiotic therapy.[ 11 ]

Table 1:

Published cases spinal infections by Citrobacter koseri.

Antibiotic sensitivity of C. koseri

C. koseri is typically sensitive to ciprofloxacin, carbapenems, third-generation cephalosporins, piperacillin-tazobactam, aminoglycosides, and trimethoprim-sulfamethoxazole, but are typically markedly or moderately resistant to multiple other AB [ Table 2 ].[ 1 , 3 , 4 , 8 ]

Table 2:

Summary of antibiotic therapy for C. koseri.

CONCLUSION

SEA caused by C. koseri is very rare. However, once recognized in conjunction with significant neurological deficits, they typically require surgical decompression/aggressive debridement and prolonged postoperative antibiotic therapy.

Declaration of patient consent

Patient’s consent not required as patient’s identity is not disclosed or compromised.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Disclaimer

The views and opinions expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Journal or its management. The information contained in this article should not be considered to be medical advice; patients should consult their own physicians for advice as to their specific medical needs.

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