Pyogenic spondylodiscitis is an uncommon but important clinical condition that often requires medical and/or surgical management. In the SA Medical Journal, two South African specialists, J Pillay and NM van der Linden, report a case of spondylodiscitis caused by a rare pathogen, Gemella morbillorum, and which was successfully treated after diagnosis.
To date, worldwide, only six such cases of confirmed spondylodiscitis infection with this rare pathogen have been documented, and this is the first reported case in this country.
The patient was a 55-year-old female who presented with a month-long history of severe back pain radiating to her left leg. She said she had visited the dentist around the time of onset of the symptoms.
A workup showed raised inflammatory markers, and a positron emission tomography scan indicated features of discitis at level L2/L3.
Tissue cultures from a biopsy identified G. morbillorum species infection, and she was treated successfully with antibiotics for six weeks. It is important to have a high index of suspicion when a patient has a history of dental work, and to rule out associated infection such as endocarditis. Treatment with culture-driven antibiotics yields good results
The most common causative organisms are Staphylococcus aureus, Streptococcus species, Escherichia coli and Proteus. Antibiotic therapy is often guided by identification of the causative organism.
Case presentation
The 55-year-old woman gave a history of a previous lumbar fusion and decompression L3 – S1 3 years before this, without any perioperative complications.
At the time of presentation, she was in severe pain, with a Visual Analogue Scale of 8/10, and a claudication distance of <50 metres.
She was clinically stable without any fever, and neurological examination was normal.
The workup done for her included a full blood count, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), X-rays and a magnetic resonance imaging (MRI) scan of her lumbar spine.
The blood workup revealed a CRP count of 134 mg/L, ESR of 75 mm/hr and a mild lymphocytosis. X-rays showed a lumbar fusion from L3 – S1 without any signs of hardware loosening. The MRI scan showed L2/L3 disc herniation with impression of increased signal on T2 and STIR images.
A further sepsis workup was then performed. A full body positron emission tomography scan showed features suggestive of a discitis, with increased 18-F-fluorodeoxyglucose uptake at level L2/L3, which was above the levels of the previous surgery.
There were no signs of infection or loosening of the existing hardware. As part of the workup and to identify any possible aetiology, blood cultures, an echocardiogram and abdominal sonar were also done.
However, all of these were normal and there was no growth on blood cultures.
The patient was taken to theatre for a discectomy and biopsy of the L2/L3 disc space. Several tissue samples were sent to the lab for processing, and after five days, a positive culture of G. morbillorum on disc material was isolated and found to be sensitive to beta-lactams and vancomycin.
The patient was treated with one-week intravenous infusion Augmentin, and the CRP came down to 11 mg/L, and the ESR down to 29 mm/hr. She was then discharged on oral Augmentin for five weeks.
The blood markers were both within normal limits after this time, and the patient no longer had any back or leg pain.
Discussion
G. morbillorum is a Gram-positive, catalase-negative anaerobic coccus that is part of a spectrum of the Gimella species. It can be found as part of normal flora in mucous membranes, such as the gastrointestinal (GI) tract, the upper respiratory tract and the oral cavity.
Although infection with G. morbillorum is rare, there has been an association with infective endocarditis, brain abscesses, liver abscesses and pharyngeal abscesses.
In a recent review of osteoarticular infection caused by G. morbillorum by Saad et al, the authors reported only six confirmed G. morbillorum spondylodiscitis cases, and to our knowledge this is the first reported case in SA.
Infections with G. morbillorum have been identified in all age groups, and In most cases, there seem to be underlying risk factors that predispose to the infection.
Since the species exists in normal flora, the most common risk factors are recent dental procedures/infections, poor oral health, recent endoscopic or colonoscopic examinations, host immune suppression and recent blunt trauma.
Although in some cases there can be no underlying factor, or none that can be identified, our patient reported she’d had toothache and seen her dentist around the same time as the onset of the pain.
This was consistent with Saad et al.’s finding that two of the six cases reported dental infections, and that in contrast to arthritis, a possible source was identified in 75% of spondylodiscitis cases.
Several predisposing factors can increase the risk of developing spondylodiscitis, including diabetes mellitus, the most commonly identified risk factor; immunosuppression, encompassing individuals with compromised immune systems like those with HIV/Aids, and other factors like advanced age, intravenous drug use, smoking and hepatic cirrhosis.
However, the patient in this study had no identifiable predisposing factors for spondylodiscitis.
As part of the initial management, an assessment of a potential source is advised, with a focused workup that could include an echocardiogram or gastroscopy or colonoscopy for GI sources.
Blood cultures are also recommended, and can be positive in up to 50% of cases, but this was not the case in our patient.
Lab investigations like a white blood cell count, CRP and ESR levels can help, while tissue diagnosis of the disc material after a biopsy or discectomy for culture is the most appropriate method to identify the species.
Treatment for G. morbillorum is focused on appropriate antibiotic use, with or without surgery.
The species is generally susceptible antimicrobial agents, including penicillin, ampicillin, clindamycin and vancomycin, and resistance is very rare.
The antibiotic treatment should, however, be culture driven, and the recommended guideline is six weeks of antibiotics, which can be extended in patients with poor immune status.
Surgery is focused on source control, and a tissue biopsy can be done at the same time.
Absolute indications for surgery are patients with progressive neurological deficits due to spinal cord compression, while relative indications include failed conservative management, ongoing significant pain or bio-mechanical instability.
If none of these is present, antibiotic treatment alone is generally appropriate.
Patients treated with appropriate culture-based antibiotics and surgery, if necessary, have complete recovery and are back to functional status within six weeks to a few months.
Risk factors for infections caused by G. morbillorum include recent dental procedures/infections, poor oral health, recent endoscopic or colonoscopic examinations, host immune suppression and recent blunt trauma.
Given these risk factors, one might consider that prophylactic antibiotic use during minor dental procedures/infections or other minor procedures such us endoscopic/colonoscopic examinations could potentially reduce the risk of G. morbillorum infections.
For patients at high risk for infective endocarditis or those who are immunocompromised, prophylactic antibiotics are recommended to prevent infections.
This includes antibiotics effective against oral flora, including G. morbillorum.
For patients at lower risk, routine prophylaxis is not generally recommended, but specific cases might warrant it based on individual risk factors.
J Pillay – MB ChB, FC Orth (SA), Mediclinic Kloof Hospital, Erasmuskloof; Department of Orthopaedics, Steve Biko Academic Hospital, Pretoria.
NM van den Linden – BCMP, Department of Orthopaedics, Steve Biko Academic Hospital, Pretoria.