Case of Adult Escherichia Coli Meningitis

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bacterial meningitis causes potentially life-threatening neurological complications [1]. In contrast to Streptococcus pneumoniae and Neisseria meningitis [2], Escherichia coli (E. coli) rarely causes adult meningitis, accounting for approximately 1% of meningitis cases [2,3], although this disease is a healthcare-associated infection and occurs especially aftertraumatic craniocerebral injury or as a neurosurgical procedure complication [4]. Furthermore, E. coli meningitis (EcM) patients have higher mortality rate than those with other bacterial meningitis [3,5]. However, patients admitted to long-term care facilities (LTFCs) almost always have preexisting risk factors to EcM (e.g. advanced age, cancer or diabetes mellitus history). Furthermore, their disease typically occurs secondary to a distant or contiguous infection focus (e.g. urinary tract or gastrointestinal infection or otitis media) [3,5]. However, reported cases of adult EcM in LTFCs are limited.

We describe a case of a 49-year-old man admitted at a LTCF who previously suffered from cerebral vascular accident with multiple infarction haemorrhages over the right cerebellum and respiratory failure. He had hydrocephalus and neurogenic bladder and underwent ventriculoperitoneal (VP) shunting and cystostomy, respectively, as treatments 6 years ago. He was admitted to our institute because of changes in consciousness and low blood pressure. Initially, he had a body temperature of 38.6 °C, pulse rate of 132/min and blood pressure of 80/ 50 mm Hg; his respiratory rate was equivalent to the ventilator rate. Neurological examination was difficult to perform but no significant abnormalities (e.g., meningeal signs) or new neurological deficits were observed. Physical examination of the respiratory system revealed coarse breathing sounds. Laboratory results on the 1^st admission day showed markedly increased white blood cell (WBC) count (12,200/ μL), C-reactive protein (7.65 mg/ dL), and serum glucose levels (160 mg/ dL). No definite new and active lung lesion was observed on the initial chest imaging. However, brain computed tomography (CT) displayed one left prefrontal ovoid lesion (size 31 mm). Hence, an immediate lumbar puncture was conducted. Cerebral spinal fluid examination revealed WBC, protein, and glucose levels of 1,120/ cm³, 192 mg/dL (normal range, 15–45 mg/dL), and 2 mg/dL (normal range, 40–70 mg/dL), respectively. A central nervous system infection was suspected; antimicrobial treatment with ceftazidime (2 g intravenous (IV) every 8 hours) and vancomycin (500 mg IV every 6 hours) was started. On the 2^nd admission day, E. coli was identified from blood and CSF specimens using matrix-assisted laser desorption/ ionization- time-of-flight mass spectrometry (bioMérieux, Hazelwood, MO). An antimicrobial drug susceptibility test [6] was conducted through the bioMérieux VITEK 2 system (bioMérieux). The minimal inhibition concentration levels were listed at Tab. 1 (Supplementary Tab. 1 online). After pathogen identification, we performed additional diagnostics to identify the primary infection focus. Although the patient was vegetarian, his past medical history showed absence of significant predisposing factors (e.g., previous EcM), except for craniotomy and VP shunting. Furthermore, chest X-ray revealed old lesions, and abdominal lesions were detected during the brain CT conducted at admission. However, these results did not reveal the primary focus. Thus, gallium scan was initially performed, followed by pelvis CT. The CT findings indicated abscess formation in the left psoas muscle and pericecal region that was complicated with fluid collection around the left abdominal wall and the VP shunt catheter tip. Thus, emergent operation was performed to aspirate the psoas muscle abscess under sonographic guidance. Furthermore, abdominal wall abscess debridement and VP shunt removal were conducted. The abdominal abscess culture showed polymicrobes (e.g., E. coli, Klebsiella pneumoniae, and Candida albicans). The antimicrobial regimen was changed from ceftazidime and vancomycin to imipenem- cilastatin (250 mg IV every 8 hours) and fluconazole (200 mg IV daily). However, imipenem- cilastatin was replaced with meropenem (2 m IV every 8 hours) because of a tonic-clonic seizure attack after 5 days of medication administration. Despite the treatment, the patient’s condition deteriorated. Specifically, he required mechanical ventilation that resulted in ventilator-associated pneum-onia. His general condition continued to worsen and this had prompted his family to request discharge due to medical futility.

We report the first case of an adult EcM from a LTCF in Changhua County. Some studies on healthcare-associated meningitis reported that patients are particularly prone to this disease because of subsequent microorganism penetration owing to traumatic craniocerebral injury or neurosurgical procedures [2,4,5]. In our patient, there was an evidence of possible healthcare-associated meningitis, in which E. coli originated from the psoas muscle abscesses and was transmitted via the VP shunt. Considering that adult EcM is rarely suggested as a cause of a central nervous system infection, we conducted an evidence-based literature review. Worldwide, 112 adult patients with EcM were reported (Supplementary Tab. 2 online). The crude mortality rate ranged from 65% [7] to 2.5% [8]. The majority of EcM cases was observed in patients with predisposing risk factors, such as advanced age [5], cancer history [5], nosocomial acquisition [5], cerebrospinal fluid fistula [9], cranial surgery [9], chronic otitis media [9], and trauma [10]. However, our patient did not display any of these risk factors except from craniectomy and VP shunt insertion 7 years ago. Moreover, approximately 75% of the cases [3,4] occurred secondary to a distant or contiguous infection (e.g. urinary tract infection). Thus, the dia­gnostics in this case were extended after pathogen identification to identify the primary infection focus, resulting in the diagnosis of previously unrecognized psoas muscles abscesses. Consequently, our report emphasizes the importance of searching for the source of adult EcM, especially if no typical risk factors are identified.

EcM in adult patients is a rare and fatal disease that usually has risk factors. Performing an extended diagnostic examination to exclude underlying diseases and possible precedent infections is advised if no typical risk factors or the original focus are identified.

Acknowledgements

The authors thank the Changhua Christian Hospital for their kind gift of clinical Escherichia coli.

The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study.

The Editorial Board declares that the manuscript met the ICMJE “uniform requirements” for biomedical papers.

Chen Chang-Hua, MD

Division of Infectious Disease

Department of Internal Medicine

Changhua Christian Hospital

Nanhsiao Street

Changhua 500

Taiwan

e-mail: 76590@cch.org.tw

Accepted for review: 21. 2. 2017

Accepted for print: 11. 5. 2017