An Unusual Case of Campylobacter jejuni Gastroenteritis Presenting with Acute Reversible Encephalopathy in an Immunocompetent Host

Campylobacter jejuni gastroenteritis is the most frequent organism associated with acute infectious diarrhea worldwide. The clinical presentation involves fever, diarrhea, rigors, and myalgias. Other extraintestinal symptoms that have been described involve delirium and other neurological complications, and the most well-known is Guillain-Barré, where there is cross-reactivity between the gastrointestinal tract and the brain. Despite previously described multiple neurological complications, there is a lack of clinical data on the association of Campylobacter-related gastroenteritis with acute encephalopathy in immunocompetent patients. The type of population, immunocompetent stage, and unfamiliarity with the clinical presentation makes this a challenging diagnosis for clinicians. We report a case of Campylobacter gastroenteritis associated with acute encephalopathy in an immunocompetent patient.


Introduction
Campylobacter jejuni (C. jejuni) is the most frequent organism associated with acute bacterial gastroenteritis around the world [1]. e high incidence of Campylobacter diarrhea, as well as its duration and possible complications, makes it highly important from a socioeconomic perspective [2]. It is estimated to cause 1.3 million human illnesses every year with 96 million cases in 2010 in the United States [3]. e clinical presentation is characterized mainly by abdominal pain and diarrhea. A prodrome phase characterized by fever, rigors, myalgias, and occasional delirium has been described [2]. e most well-known postinfectious neurological complications are Guillain-Barré syndrome (GBS) and Miller-Fisher syndrome (MFS) [4]. Furthermore, worldwide the patient was in her usual state of health until one week before this admission when she started to experience abdominal pain and diarrhea. e patient's mother described episodes of anxiety and unusual behavior-associated confusion specially the day before admission.
On the day of admission, the patient sought medical attention at an outpatient clinic. While in the office, she became confused and later she experienced a witnessed seizure. e patient received a dose of lorazepam prior to arrival at the hospital. On arrival to the emergency department, she was found unresponsive with a Glasgow Coma Scale of six. She was afebrile and tachycardic with a heart rate of 115 beats per minute. e rest of her vital signs were within normal limits.
Her physical exam was remarkable for generalized decreased muscle tone and no clear focal deficits. e patient was intubated for airway protection. She was given a loading dose of levetiracetam and was admitted to the neurosciences intensive care unit.
Her initial laboratory tests showed respiratory alkalosis with an elevated white blood cell count at 11.6 th/μl with 76.5% of neutrophils. Her complete metabolic panel showed hypokalemia. Her urine toxicology, serum alcohol levels, and urine analysis were unremarkable. C-reactive protein was 3.3 mg/dL, and her lactic acid was 1.2 mmol/L. Blood tests are summarized in Table 1.
A brain computed tomography (CT) without contrast showed slightly increased low density in the left occipital white matter compared to the right which increased the suspicion of posterior reversible encephalopathy syndrome (PRES), and these images are shown in Figure 1. Herpes simplex virus (HSV) encephalitis and autoimmune epilepsy were also considered in the differential diagnosis. e brain CT with perfusion was negative for stroke. Chest X-ray showed atelectatic changes in the right upper lobe. A CT of the abdomen and pelvis was negative for ovarian teratoma. e patient was started on acyclovir for suspected herpetic encephalitis.
A brain magnetic resonance (MRI) was negative for findings supporting the diagnosis of PRES. e electroencephalogram showed no evidence of seizure activity or epileptiform discharges. Lumbar puncture was performed, and the cerebrospinal fluid (CSF) had a clear appearance. e opening pressure was normal. e CSF glucose was elevated at 91 units. e CSF white blood cell count was 3/μL. Further studies on CSF for ruling out meningitis were done, and they included Cryptococcus neoformans/gattii, Cytomegalovirus, Enterovirus CSF, E. coli K1, Hemophilus influenzae, Human Parechovirus, Listeria monocytogenes, Neisseria meningitidis, Streptococcus agalactiae, Streptococcus pneumoniae, varicellazoster, and herpes simplex virus 1, 2, and 6, which were negative; details are shown in Table 2.
e infectious disease team was consulted, and doxycycline was added due to the high prevalence of typhus in the area. Febrile agglutinins, West Nile virus, and fungal serologies were also negative ( Table 1).
Due to persistent diarrhea during the initial day of admission, a gastrointestinal infectious panel was ordered and was positive for C. jejuni (Table 3).
Based on the clinical scenario of a patient with extraintestinal complications of Campylobacter infection, it was decided to start azithromycin 500 mg per mouth for at least 10 days. e patient showed significant improvement after the first dose and recovered over the next few days prior to discharge.

Discussion
We are describing a case of Campylobacter jejuni gastroenteritis associated with acute encephalopathy in an immunocompetent adult.
e complex initial presentation with neurological symptoms makes this clinical scenario a diagnostic challenge due to the unfamiliarity of clinicians with this disease.
Campylobacter species belongs to a distinct group of specialized Gram-negative bacteria designated as rRNA superfamily VI [10]. e most important species that can cause human disease are C. jejuni and C. coli [11]. Campylobacters invade the intestinal epithelium using flagella, high molecular weight plasmids, superficial adhesins, and chemotactic factors [12].
Patients infected with C. jejuni gastroenteritis experience acute watery or bloody diarrhea, fever, weight loss, and cramps that last six days on average [11]. Besides the gastrointestinal local infection, Campylobacter species also can cause a range of other clinical manifestations or postinfectious immune disorders [13].
While infection with C. jejuni can occur in patients of all ages, this infection is more prevalent in toddlers and young adults than in other age groups [14]. Despite most of the neurologic complications associated with Campylobacter enteritis have been historically linked to the pediatric population, some of these manifestations have been also described in adults [9].
Our patient had an unusual presentation of C. jejuni gastroenteritis associated with acute encephalopathy. Based on her initial symptoms, she was treated with acyclovir for the suspicion of HSV encephalitis. Moreover, the combination of seizures in association with the abnormalities noted in the mentioned neuroimaging raised the initial suspicion for PRES and autoimmune epilepsy. ese diagnoses were ruled out with a brain MRI and a CSF autoimmune panel, respectively [15][16][17].
Other autoimmune systemic diseases including lupus and vasculitis were ruled out with negative ANCA, ANA, and dsDNA. We also considered ADEM following a C. jejuni gastroenteritis in our differential diagnosis. Nonetheless, the MRI did not show increased T2-signal intensity in the white matter which is a characteristic neuroimaging finding in ADEM [4]. Furthermore, patients suffering ADEM only improve with high-dose steroids that our patient never received [4].
Based on Rio Grande Valley demographics with high prevalence of murine typhus in the area, the patient was treated empirically with doxycycline until her agglutinins