Next-Generation Sequencing-Based Diagnosis of Bacteremic Listeria monocytogenes Meningitis in a Patient with Anti-Interferon Gamma

Autoantibodies: A Case Report

Abstract

Although various opportunistic infections have been described in patients with anti-interferon gamma autoantibodies, so far there is no Listeria monocytogenes infection reported to be associated with this primary immunodeficiency. Here, we describe the first case of bacteremic L. monocytogenes meningitis in a 59-year-old Chinese man with anti-interferon gamma autoantibodies, who presented with acute onset of fever and severe headache. Blood culture was positive but culture of the cerebrospinal fluid was negative, although it showed features suggestive of partially treated bacterial meningitis. The presence of L. monocytogenes in the cerebrospinal fluid was confirmed by next-generation sequencing. Avoidance of high-risk food items in these patients is important for the prevention of listeriosis. The use of antibiotic regimens that cover Listeria is crucial for empirical treatment, particularly if such patients develop acute or subacute meningitis. Next-generation sequencing is becoming an important diagnostic modality for culture-negative infections.

Introduction

During the last decade, there has been a marked increase in the successful elucidation of molecular mechanisms behind primary immunodeficiency syndromes that result in opportunistic infections, including immunodeficiencies such as anti-interferon gamma autoantibodies and mutations in various immunological pathways. In the same period of time, the surge in the use of targeted therapies, such as kinase inhibitors and antibodies against various targets in the immunological pathways, has also led to opportunistic infections associated with patients undergoing these treatments, resulting in secondary immunodeficiency.^1,2 In this report, we describe the first case of bacteremic Listeria monocytogenes meningitis in a patient with anti-interferon gamma autoantibodies. The use of next-generation sequencing (NGS) for laboratory diagnosis is also discussed.

Case report

A 59-year-old Chinese man was admitted in June 2021 because of acute onset of fever, severe headache, and malaise for 1 day. The patient first presented with on-and-off fever, neck mass, and chest and back pain in March 2019, which lasted for 2 months. There was no history of animal contact or pulmonary tuberculosis. Examination showed that the patient had a lowgrade fever and cervical lymphadenopathy. There was also tenderness at multiple sites on the chest wall and at the lower thoracic and lumbar spine levels. A positron emission tomography scan showed increased uptake at T10, T12, L1, and the right humerus. A cervical lymph node biopsy was performed and Talaromyces marneffei was isolated. Bone biopsies of T10 and the right humerus were performed, but bacterial, fungal, and mycobacterial cultures were all negative. Human immunodeficiency virus antibodies were also negative. The patient was treated with intravenous liposomal amphotericin B (5 mg/kg/day) followed by oral voriconazole (200 mg every 12 hours) for 12 months. In the following 2 years, the patient had recurrent and refractory genital herpes. Oral valacyclovir (500 mg twice a day), intravenous cidofovir (375 μg once every 2 weeks), and intramuscular interferon a-1b (30 μg twice a week) were prescribed intermittently. In May 2021, the patient had persistent generalized bone pain and increased lower back pain. A positron emission tomography scan showed that there was persistent increased uptake with more extensive involvement at T10, T12, L1, and the right humerus. In view of the patient recent medical history including T. marneffei and recurrent genital herpes infections in the absence of obvious immune defects, an immunological workup was performed. This revealed the presence of anti-interferon gamma autoantibodies according to an in-house method developed by Tang et al.³

In the present admission, the illness began with high-grade fever, severe headache, and fatigue. In addition, there was persistent generalized bone pain for 2 years, but the cause remained obscure. Examination showed that his temperature was up to 39.6°C, but there were no localizing symptoms. His oxygen saturation was 99% on room air. His total white cell count was 24.5 × 10⁹/L (normal range, 3.89-9.93 × 10⁹/L), with neutrophils at 21.2 × 10⁹/L (normal range, 2.01-7.42 × 10⁹/L). Liver and renal function tests were mildly deranged. The erythrocyte sedimentation rate was 110 mm/hour (normal range, 0-15 mm/hour), his C-reaction protein level was 282.4 mg/L (normal range, <5 mg/L) and his plasma procalcitonin level was 0.512 ng/mL (normal range, <0.1 ng/mL). Blood cultures were performed and empirical intravenous piperacillin-tazobactam (4.5 g every 8 hours) and voriconazole (200 mg every 12 hours) were commenced. After 21 hours of incubation, the aerobic blood culture bottle was positive for a Gram-positive rod, which was subsequently identified as L. monocytogenes by conventional biochemical tests and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. It was susceptible to penicillin (minimal inhibitory concentration 0.5 μg/mL). A lumbar puncture performed 2 days after the commencement of antimicrobial therapy showed an opening pressure of 160 mm H₂O. The cerebrospinal fluid (CSF) was colorless and transparent, with a cell count of 387 × 10⁶/L (normal range, 0-5 × 10⁶/L) with 8% neutrophils, 10% lymphocytes and 82% monocytes, glucose at 2.8 mmol/L (normal range, 2.2-3.9 mmol/L) (random blood glucose was 6.3 mmol/L) and protein levels at 373 mg/L (normal range, 150-450 mg/L). A Gram smear showed suspected Gram-negative rods, but culture was negative. The CSF was sent for NGS analysis, which revealed seven sequence reads of L. monocytogenes, confirming the diagnosis of acute bacteremic L. monocytogenes meningitis. Piperacillin-tazobactam was stopped and high dose intravenous ampicillin (2 g every 4 hours) was commenced.

The patient only partially responded to ampicillin and the generalized bone pain persisted. Therefore, a sacral biopsy was performed. A Ziehl-Neelsen stain was positive and histological examination also revealed acid-fast bacilli with epithelioid cells and abundant neutrophil, plasmocyte, and lymphocyte infiltration. The antimicrobial regimen was switched to intravenous meropenem (2 g every 8 hours) and amikacin (500 mg every 24 hours) and oral clarithromycin (500 mg every 12 hours), rifampicin (300 mg every 12 hours), and ethambutol (1 g every 24 hours); and subsequently to intravenous meropenem (2 g every 8 hours), amikacin (500 mg every 24 hours), tigecycline (50 mg every 12 hours), linezolid (600 mg every 24 hours) and oral ethambutol (1 g every 24 hours). The fever completely subsided 4 days afterward. Mycobacterium kansasii was isolated from the bone biopsy. The patient was discharged 34 days later with oral clarithromycin (500 mg every 12 hours), linezolid (600 mg every 24 hours), ethambutol (1 g every 24 hours), and rifampicin (300 mg every 12 hours). His infections have remained in remission at the time of writing, 2 months from discharge.

Discussion

Since its discovery in 2004,⁴ numerous infections, particularly those due to intracellular pathogens, have been observed in patients with anti-interferon gamma autoantibodies. Since first launching of the anti-interferon gamma autoantibody laboratory test in our hospital 7 years ago, five cases, including the present one, have been diagnosed to have this immunological disease (Table 1). Out of the five patients, three had a T. marneffei infection (cases 2, 4, and 5) and three had a non-tuberculous mycobacterial infection (cases 1, 3, and 5), in line with common infections observed in these patients. In this article, we report the first case of listeriosis in a patient with anti-interferon gamma autoantibodies. Listeriosis is a food-borne infection caused by L. monocytogenes or Listeria ivanovii. It is usually caused by consumption of unpasteurized milk and dairy products, and sometimes contaminated ice-cream and salads as these bacteria can survive and multiply efficiently at 4°C.⁵ Nevertheless, in some patients, including the one in the present report, the culprit is not obvious. In immunocompetent hosts, listeriosis usually manifests as self-limiting gastroenteritis. However, in immunocompromised patients, such as pregnant women, elderly, and neonates, and in some other immunodeficiency states, Listeria infections may result in systemic sepsis with bacteremia (as in the present case), and most severe central nervous system infections (also observed in the present case).⁶ As L. monocytogenes and L. ivanovii are facultative intracellular pathogens, patients with listeriosis are often those with cell-mediated immunity defects, such as transplant recipients, those on corticosteroids, acquired immunodeficiency syndrome patients, and Mendelian susceptibility to mycobacterial disease patients.^6,7 In addition, it has also been reported in patients receiving proteasome inhibitors.² Therefore, it is not unexpected to encounter bacteremic L. monocytogenes meningitis in the present case with anti-interferon gamma autoantibodies.

Table 1 - Pathogens detected in patients with anti-interferon gamma autoantibodies in our hospital

Case	Year of detection of anti-interferon gamma autoantibodies	Time lag between initial presentation of opportunistic infection and detection of anti-interferon gamma autoantibodies	Anti-interferon gamma autoantibodies titer	Pathogens detected
1	2014	6 months	>1:1000	Mycobacterium abscessus
2	2020	31 months	>1:1000	Mycobacterium tuberculosis Talaromyces marneffei
3	2021	48 months	>1:1000	Mycobacterium kansasii
4	2021	5 months	>1:1000	T. marneffei Klebsiella pneumoniae
5 (present case)	2021	26 months	>1:1000	T. marneffei Herpes simplex virus Listeria monocytogenes M. kansasii

NGS is becoming an important diagnostic modality for culture-negative infections. Culture-negative endocarditis, meningitis, and other infectious disease syndromes caused by difficult-to-grow microbes or partially treated bacterial infections have posed a lot of difficulties in laboratory diagnosis of infectious diseases. In the recent few years, with the improvement of sequencing chemistries, computer hardware and software, and computational capacity, NGS technologies have matured to the extent that they can be used in selected patients with culturenegative infections.^8,9 The recent invention of the Oxford Nanopore Techonologies’ MinION device has also facilitated the use of NGS for laboratory diagnosis of infectious diseases because of its low equipment cost, portable size, and short turnaround-time. In the present case, although L. monocytogenes was isolated from the patient’s blood and his CSF cell count suggested partially treated meningitis as the patient had been on intravenous piperacillin-tazobactam for 2 days before the lumbar puncture was performed, no bacterium was recovered from the CSF. The diagnosis of Listeria meningitis was only confirmed after the detection of seven sequence reads of L. monocytogenes in the CSF. It is of note that L. monocytogenes is not an uncommon pathogen diagnosed by NGS, with most of the illnesses involved manifesting as culture-negative meningitis.^10-12

Concluding remarks

We report the first case of bacteremic L. monocytogenes meningitis in a patient with anti-interferon gamma autoantibodies. Laboratory diagnosis was made by a combination of conventional microbiological tests and NGS technology. Avoidance of high-risk food items in patients with anti-interferon gamma autoantibodies is important for the prevention of listeriosis. The use of antibiotic regimens that cover Listeria is crucial for empirical treatment, particularly if such patients develop acute or subacute meningitis.