Copyright
©The Author(s) 2025. Published by Baishideng Publishing Group Inc. All rights reserved.
Recurrence of acyclovir-resistant herpes encephalitis in an immunocompromised patient: A case report
Daisuke Usuda, Daiki Furukawa, Rikako Imaizumi, Rikuo Ono, Yuki Kaneoka, Eri Nakajima, Masashi Kato, Yuto Sugawara, Runa Shimizu, Tomotari Inami, Kenji Kawai, Shun Matsubara, Risa Tanaka, Makoto Suzuki, Shintaro Shimozawa, Yuta Hotchi, Ippei Osugi, Risa Katou, Sakurako Ito, Kentaro Mishima, Akihiko Kondo, Keiko Mizuno, Hiroki Takami, Takayuki Komatsu, Tomohisa Nomura, Manabu Sugita
Daisuke Usuda, Daiki Furukawa, Rikako Imaizumi, Rikuo Ono, Yuki Kaneoka, Eri Nakajima, Masashi Kato, Yuto Sugawara, Runa Shimizu, Tomotari Inami, Kenji Kawai, Shun Matsubara, Risa Tanaka, Makoto Suzuki, Shintaro Shimozawa, Yuta Hotchi, Ippei Osugi, Risa Katou, Sakurako Ito, Kentaro Mishima, Akihiko Kondo, Keiko Mizuno, Hiroki Takami, Takayuki Komatsu, Tomohisa Nomura, Manabu Sugita, Department of Emergency and Critical Care Medicine, Juntendo University Nerima Hospital, Nerima 177-8521, Tokyo, Japan
Takayuki Komatsu, Department of Sports Medicine, Faculty of Medicine, Juntendo University, Bunkyo 113-8421, Tokyo, Japan
Author contributions: Usuda D wrote the manuscript; Furukawa D, Imaizumi R, Ono R, Kaneoka Y, Kato M, Sugawara Y, Shimizu R, Inami T, Kawai K, Matsubara S, Tanaka R, Suzuki M, Shimozawa S, Hotchi Y, Osugi I, Katou R, Ito S, Mishima K, Kondo A, Mizuno K, Takami H, Komatsu T, Nomura T, and Sugita M proofread and revised the manuscript. All authors approved the final version to be published.
Supported by the Japan Society for the Promotion of Science KAKENHI Grant, No. JP24K15491.
Informed consent statement: Written informed consent was obtained from surety of the patient for publication of this case report and any accompanying images. Both written and verbally informed consent were obtained from the patient for publication of this case report and any accompanying images.
Conflict-of-interest statement: All the authors report no relevant conflicts of interest for this article.
CARE Checklist (2016) statement: The authors have read the CARE Checklist (2016), and the manuscript was prepared and revised according to the CARE Checklist (2016).
Open Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
https://creativecommons.org/Licenses/by-nc/4.0/ Corresponding author: Daisuke Usuda, MD, PhD, Associate Professor, Department of Emer
gency and Critical Care Medicine, Juntendo University Nerima Hospital, 3-1-10, Takanodai, Nerima 177-8521, Tokyo, Japan.
d.usuda.qa@juntendo.ac.jp
Received: July 1, 2025
Revised: September 4, 2025
Accepted: November 21, 2025
Published online: December 6, 2025
Processing time: 159 Days and 3.7 Hours
BACKGROUND
Acyclovir (ACV)-resistant herpes simplex virus (HSV) strains have emerged and gradually increased in number. Prolonged treatment, such as for immunocompromised patients, has been observed on many occasions to lead to the development of resistance. Additionally, some strains of HSV exist that are ACV resistant, and they can cause severe complications that may be impossible to treat with current therapies. We report the first case of ACV-resistant herpes encephalitis (ARHE) recurring in an immunocompromised adult patient without neurosurgical intervention.
CASE SUMMARY
A 58-year-old man with a fever of 38°C had tremors. Evaluation revealed 14 points on the Glasgow Coma Scale with 39°C fever but unremarkable physical examination. Diagnosis was infection of unknown origin; fever continued, and the Glasgow Coma Scale worsened to 8. Imaging showing a high-intensity area between the left temporal lobe and insular cortex suggested herpes encephalitis. ACV was started. Cerebrospinal fluid (CSF) was positive for HSV DNA, confirming the diagnosis. However, unresolved symptoms suggested ARHE; therefore, we initiated vidarabine treatment. Later testing confirmed ARHE. Foscarnet was started based on a hospital day 25 blood test revealing pancytopenia, possibly from vidarabine. Consciousness improved, and the patient moved to rehabilitation. However, symptoms worsened, suggesting recurrence. Diffusion-weighted magnetic resonance imaging revealed a high high-intensity area around the right temporal lobe; CSF was positive for HSV DNA, confirming recurrent herpes encephalitis. ACV and foscarnet were initiated. Fever decreased, consciousness improved, and HSV DNA on hospital days 78 and 93 was CSF negative. Treatment was terminated on hospital day 86.
CONCLUSION
ARHE recurred in the patient following remission; therefore, it is necessary to discuss the length of the treatment period.
Core Tip: Acyclovir (ACV)-resistant herpes simplex virus strains have emerged and gradually increased in number. We report the first case of ACV-resistant herpes encephalitis (ARHE) recurring in an immunocompromised adult patient without neurosurgical interventions. Clinicians should recognize this condition because treatment for ARHE is limited, and it often develops into severe herpes disease that is refractory to antiviral drug therapy. In addition, ARHE recurred in the patient following remission; therefore, it is necessary to discuss the length of the treatment period. There is no established standard treatment for recurrence cases; therefore, accumulation of evidence is needed.
