R.S.Soliman, L.Clerihew, A.Jollands, M.Kirkpatrick, D Mowle.
Dr R.S.Soliman Department of Medical MicrobiologyNinewells Hospital Dundee, UK
Dr. L.Clerihew, Dr A.Jollands, M.Kirkpatrick Department of Paediatrics Ninewells Hospital
Dr Dr D Mowle Department of Neurosurgery Ninewells Hospital
Correspondence author: Dr R.S.Soliman SPR Department of Medical Microbiology - Level 6Ninewells Hospital Acute Services Division NHS Tayside - DundeeDD1 9SY
E-mail: reham.soliman@nhs.net
Keywords: Subdural empyema, Salmonella, Infantis
Abstract
Focal intracranial infections such as brain abscess, subdural empyema, or epidural abscess are unusual manifestations of salmonellosis found almost solely in immuno-compromised patients. We describe an unusual case of an 11-month old immuno-competent girl with a Salmonella Infantis subdural empyema. The case responded well to surgical drainage and long course of antibiotic treatment.
Case
Report
A previously healthy, 11 month old, female identical twin was admitted to the paediatric unit. She had presented two weeks previously to the General Practitioner with a generalised seizure presumed to be a febrile convulsion. There had been no further seizures but the infant had continued to be febrile and had been commenced on oral amoxicillin 3 days prior to admission. Six to 8 weeks earlier 5 family members had been unwell with a mild diarrhoeal and vomiting illness. Symptoms were self-limiting and the family did not contact health services.
On the day of admission her parents were concerned because of an episode of right sided shaking followed by increasing lethargy. On examination she was tachycardic with cool peripheries. She was afebrile. She was lethargic and her head was held fixed to the left. She was poorly responsive with no eye contact or spontaneous vocalisation. Her pupils were of midsize and equally reactive, fundal examination was normal. There was no facial asymmetry but there was paucity of movement, increased tone and hyperreflexia on her right side.
She was managed with fluid resuscitation and intravenous ceftriaxone and dexamethasone. A Computerised Tomography (CT) brain scan showed a large left fronto-parietal subdural collection with small ventricles bilaterally and significant midline shift to right. The peripheral white cell count was normal but a C-reactive protein (CRP) was elevated at 182mg/dl.
At operation, dark brown fluid was drained via a bur hole. Microscopy of the fluid showed many polymorphs but gram stain was negative. The following day cultures revealed a scanty growth of a coliform identified as Group C Salmonella, sensitive to amoxicillin, co-amoxiclav, ciprofloxacin, gentamicin, cefuroxime, and piperacillin-tazobactam. This was subsequently identified by the Scottish Salmonella Reference Laboratory at Stobhill as Salmonella Infantis. Stool samples from all family members were repeatedly negative on culture.
She continued to be persistently febrile and on the seventh postoperative day a further CT scan showed re-accumulation of the subdural collection. Further aspiration was undertaken and a drain left in situ. Cultures again yielded the group C Salmonella Infantis. Intravenous chloramphenicol was added to the regime (50 mg/kg/day). By day twelve she was afebrile. At day eighteen a follow –up CT scan showed only a small residual collection. Oral ciprofloxacin was substituted for intravenous ceftriaxone and chloramphenicol was continued orally. By the time of discharge from hospital there was evidence of a resolving mild right hemiplegia.
Oral antibiotics were continued for a total of six weeks. Review one month later revealed no weakness, hyperreflexia or asymmetry of tone, and developmental catch up with her twin. Eight months later MRI scan shows a small residual left frontal lesion thought to represent meningeal thickening.
Discussion
Intracranial subdural empyema is a collection of pus between the outermost meninges, the dura and the arachnoid and accounts for 15-20% of all localised intracranial infections. It is usually localised above the frontal and parietal lobes, only 3% of cases in the occipital region. 1 Mortality rates are approximately 10-20% 2. Intracranial subdural empyema is usually a complication of meningitis, sinusitis or, less frequently otitis media or neurosurgical procedures in children 3. In adults intracranial subdural empyema may be a result of trauma or head and neck surgery. Haematogenous spread is also described 4. Extra-intestinal, non-typhoidal Salmonella (NTS) infections are uncommon in developed countries 5. Three serotypes most commonly isolated in intracranial collections are S. Enteritidis, S. Typhi and S. Typhimurium. 5
Subdural
empyema caused by salmonella in childhood is an uncommon condition. 6
Increased susceptibility to salmonella infection is thought to be due to several
factors: prolonged exposures to the organism, impaired cell mediated immune
response, impairment of phagocytosis, and the presence of diseased tissue. 7
It is being increasingly reported in association with AIDS 8
Precipitating factors include meningitis, trauma, bacteraemia, otitis,
mastoiditis, and osteomyelitis of the skull, though many cases have not had any
precipitating factors.7
Strains of Salmonella Infantis do not generally carry virulence-associated plasmids and plasmid free isolates are less virulent, non invasive, and serum sensitive.9 By measuring the 50% lethal dose it was found that serotypes of S. Infantis need 106- fold more than the value needed by the plasmid positive serotypes e.g. S. Enteritidis S. Typhimurium. 9
In our case, the source of the Salmonella was not identified. There was no exposure or contact with any pets or animals. Six to 8 weeks before presentation, this child, and family members reported symptoms consistent with gastro-enteritis, but as the Family Practitioner was not consulted no samples were taken for confirmation or identification of the organism. However, during this admission repeated stool cultures from this infant and family members were negative.
Conclusion
Focal intracranial salmonella infections are rare manifestations of salmonellosis especially in the UK but can occur without an obvious predisposing illness. Surgical drainage and prolonged antibiotics are needed for treatment.
Acknowledgements:
-Scottish
Salmonella Reference Laboratory at Stobhill for identification and typing of the
organism.
-Dr G.Phillips for helpful discussion on the manuscript.
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