Atypical rat bite fever associated with knee joint infection in a Chinese patient: a case report

Abstract Background Rat bite fever (RBF) is a rare zoonosis transmitted from rodents to humans through bites and scratches. However, diagnosis and treatment of atypical clinical cases can be challenging. Case presentation Herein, we report an atypical case of RBF with unilateral knee joint infection...

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Main Authors: Mengping Gao, Shaojin Zhong, Guibin Han, Duncai Kuang, Changying Yun, Cegang Fu
Format: Article
Language:English
Published: BMC 2025-03-01
Series:BMC Infectious Diseases
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Online Access:https://doi.org/10.1186/s12879-025-10575-5
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author Mengping Gao
Shaojin Zhong
Guibin Han
Duncai Kuang
Changying Yun
Cegang Fu
author_facet Mengping Gao
Shaojin Zhong
Guibin Han
Duncai Kuang
Changying Yun
Cegang Fu
author_sort Mengping Gao
collection DOAJ
description Abstract Background Rat bite fever (RBF) is a rare zoonosis transmitted from rodents to humans through bites and scratches. However, diagnosis and treatment of atypical clinical cases can be challenging. Case presentation Herein, we report an atypical case of RBF with unilateral knee joint infection caused by Streptobacillus moniliformis. Streptobacillus moniliformis was isolated from the knee synovial fluid of the patient via microbiological culture and metagenomic next-generation sequencing (mNGS). After treatment with antibiotics and arthroscopic surgery, the patient reported symptom alleviation and was subsequently discharged home. This is the first reported detection of intraarticular histopathological changes caused by Streptobacillus moniliformis during knee arthroscopy. Conclusions In atypical cases, importantly, clinical healthcare professionals should promptly obtain microbiological culture results. When culture is negative, 16S ribosomal RNA gene polymerase chain reaction (16S rRNA PCR) or mNGS can be considered for identification, with inquiring about the patient’s disease history, including any contact with rodents. Surgical interventions, such as arthroscopy, may be included in treatment. Streptobacillus moniliformis infection should be considered when considerable fibrous connective tissue and capillary proliferation are observed under arthroscopic guidance.
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issn 1471-2334
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publishDate 2025-03-01
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series BMC Infectious Diseases
spelling doaj-art-e23b5a6100a14edba81f7db4dd038c1d2025-08-20T03:05:56ZengBMCBMC Infectious Diseases1471-23342025-03-012511710.1186/s12879-025-10575-5Atypical rat bite fever associated with knee joint infection in a Chinese patient: a case reportMengping Gao0Shaojin Zhong1Guibin Han2Duncai Kuang3Changying Yun4Cegang Fu5Department of Pharmacy, Haikou Orthopedic and Diabetes Hospital, Haikou Orthopedic and Diabetes Hospital of Shanghai Sixth People’s HospitalDepartment of Pharmacy, Affiliated Haikou Hospital of Xiangya Medical College, Central South UniversityDepartment of Orthopedics, Affiliated Haikou Hospital of Xiangya Medical College, Central South UniversityDepartment of Orthopedics, Haikou Orthopedic and Diabetes Hospital, Haikou Orthopedic and Diabetes Hospital of Shanghai Sixth People’s HospitalDepartment of Laboratory, Haikou Orthopedic and Diabetes Hospital, Haikou Orthopedic and Diabetes Hospital of Shanghai Sixth People’s HospitalDepartment of Orthopedics, Haikou Orthopedic and Diabetes Hospital, Haikou Orthopedic and Diabetes Hospital of Shanghai Sixth People’s HospitalAbstract Background Rat bite fever (RBF) is a rare zoonosis transmitted from rodents to humans through bites and scratches. However, diagnosis and treatment of atypical clinical cases can be challenging. Case presentation Herein, we report an atypical case of RBF with unilateral knee joint infection caused by Streptobacillus moniliformis. Streptobacillus moniliformis was isolated from the knee synovial fluid of the patient via microbiological culture and metagenomic next-generation sequencing (mNGS). After treatment with antibiotics and arthroscopic surgery, the patient reported symptom alleviation and was subsequently discharged home. This is the first reported detection of intraarticular histopathological changes caused by Streptobacillus moniliformis during knee arthroscopy. Conclusions In atypical cases, importantly, clinical healthcare professionals should promptly obtain microbiological culture results. When culture is negative, 16S ribosomal RNA gene polymerase chain reaction (16S rRNA PCR) or mNGS can be considered for identification, with inquiring about the patient’s disease history, including any contact with rodents. Surgical interventions, such as arthroscopy, may be included in treatment. Streptobacillus moniliformis infection should be considered when considerable fibrous connective tissue and capillary proliferation are observed under arthroscopic guidance.https://doi.org/10.1186/s12879-025-10575-5Streptobacillus moniliformisRat bite feverPurulent arthritisKnee arthroscopyMetagenomic next-generation sequencing
spellingShingle Mengping Gao
Shaojin Zhong
Guibin Han
Duncai Kuang
Changying Yun
Cegang Fu
Atypical rat bite fever associated with knee joint infection in a Chinese patient: a case report
BMC Infectious Diseases
Streptobacillus moniliformis
Rat bite fever
Purulent arthritis
Knee arthroscopy
Metagenomic next-generation sequencing
title Atypical rat bite fever associated with knee joint infection in a Chinese patient: a case report
title_full Atypical rat bite fever associated with knee joint infection in a Chinese patient: a case report
title_fullStr Atypical rat bite fever associated with knee joint infection in a Chinese patient: a case report
title_full_unstemmed Atypical rat bite fever associated with knee joint infection in a Chinese patient: a case report
title_short Atypical rat bite fever associated with knee joint infection in a Chinese patient: a case report
title_sort atypical rat bite fever associated with knee joint infection in a chinese patient a case report
topic Streptobacillus moniliformis
Rat bite fever
Purulent arthritis
Knee arthroscopy
Metagenomic next-generation sequencing
url https://doi.org/10.1186/s12879-025-10575-5
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