A 70 Year Old Farmer Suffering from Fatal Meningoencephalitis

Clinical History

A 70 year old former farmer and cattle breeder was admitted to a district hospital due to intermittent confusion, neuropsychological slowing with otherwise unremarkable neurological examination. His family first noticed personality changes after a right knee arthroscopy two weeks earlier.

Meningoencephalitis was suspected, spinal tab revealed a cell count of 74 cells/μL with increased protein (419 mg/dl). He developed transient febrile temperatures to 38° Celsius. Cell count decreased under therapy with Ceftriaxone and Sultamicillin (7 days later: 16 cells), several days later Standacillin was added to cover for a possible Listeria meningitis. After initial improvement of intermittent confusional states he deteriorated developing generalized myoclonic twitches and brain stem signs with somnolence, left sided ptosis, swallowing difficulties and tetraparesis. EEG showed an inconsistent left frontotemporal local lesion at admission. EEG changes progressed subsequently to a generalized diffusely slow record. 500 mg/d Levetiracetam was added to treat suspected complex focal seizures. MRI showed white matter micro vascular lesions but was otherwise unremarkable. A tine test was negative.

He was then transmitted to the neurological intensive care unit of our hospital. At this stage, he required mechanical ventilation. The control brain contrast‐enhanced T1‐weighted MRI images revealed pronounced contrast enhancement of leptomeningeal structures, particularly at the skull base and brainstem (transversal and sagittal orientation—Fig. 1a,b,c). A non‐contrast‐enhanced CT of the thorax showed a calcified small mediastinal lymph node and was otherwise unremarkable (Fig. 2b). Spinal tap was repeated and after 21 days microbiology CSF cultures grew a pathogen.

Figure 1.

 

Figure 2.

 

The patient developed hydrocephalus and external ventricle drainage was placed. Despite stabilization of ventricular pressure and specific therapy, brain stem encephalitis progressed with development of opsoclonus, recurrent spontaneous nystagmus and coma. All weaning attempts were unsuccessful and the patient died 4 months after his first symptoms had developed.

Microscopic Pathology

Microscopic workup showed diffuse infiltration of meningeal tissue with lymphocytes, plasma cells few neutrophile granulocytes and infiltration of brain stem and frontobasal cortex with lymphocytes. Fig. 1c and 2a show HE staining of brainstem tissue revealing granulation tissue with poorly formed granulomata and multinucleated giant cells of Langhans type. There was also a paratracheal lymph node with reactive lymph node tissue and necrotic granuloma (Fig 2c).

Diagnosis

Mycobacterium caprae meningoencephalitis.

CSF culture identified Mycobacterium caprae (Loewenstein‐Jensen culture positive after 21 days).

The final diagnosis was Mycobacterium caprae meningoencephalitis due to reactivation in a single paratracheal lymph node (diameter of 1,5 cm). Autopsy did not show any other lesion.

On further inquiry, his wife admitted that the patient had been involved in euthanizing cattle which had been infected with Mycobacteria in his livestock in the early 60 s. After this event, he had stopped cattle breeding. Otherwise, she could not remember any occasion, where he could have been infected.

Discussion

M. caprae is a cluster within the M. tuberculosis complex. M. caprae was mainly recognized in domestic and wild animals of continental Europe. A recent Spanish study reported M. caprae isolates in 7,4% of M. tuberculosis positive animals 3. It was found most often in cattle, followed by goats, sheep, pigs, wild boars, one red deer and one fox. M. caprae was almost never identified outside Europe (except from a European patient in Australia and a cow in Algeria).

The clinical picture of pulmonary M. bovis and M. caprae infections in humans is identical to M. tuberculosis. However, human‐to‐human transmission is very rare and mainly found in immunocompromised cases 1. Likely means of transmission are contact with livestock and contaminated food (especially milk). In Germany, between 1999 and 2001 46 patients were identified in suffering M. caprae infections, 35 of them between 61 and 80 years old 2. In the same series in 166 patients suffering M. bovis or M. caprae, only 4 had CNS involvement. To our knowledge, this is the only case with suspected M. caprae reactivation infecting CNS after decades.

A positive QuantiFERON® serum reaction after transfer to the neurological intensive care unit hinted to a Mycobacterium infection and tuberculostatic treatment with Isoniacid, Rifampicin and Ethambutol was started consecutively. Despite appropriate therapy, meningoencephalitis progressed with fatal outcome.