A case of brucellosis with perinephritis presented as abdominal and low back pain in China

Abstract

Background

Human brucellosis, a zoonotic infection, typically manifests as fever, fatigue, anorexia, and osteoarticular pain. We report a rare case of brucellosis complicated by perinephritis, presenting with abdominal and low back pain.

Case presentation

A 74-year-old male presented with fever, abdominal and low back pain. Initial lumbar magnetic resonance imaging (MRI) demonstrated L4–5 disc herniation with foraminal and spinal canal stenosis, while abdominal computed tomography (CT) revealed perinephric inflammation without structural abnormalities. Upon developing intermittent fever (38 °C), epidemiological history uncovered chronic consumption of uninspected sheep meat. Brucellosis with perinephritis was confirmed via supportive Brucella agglutination test and blood culture.

Conclusions

Perinephritis is an uncommon complication of brucellosis, and atypical abdominal pain warrants consideration of zoonotic exposure. Serological testing (agglutination test) and blood culture remain critical for timely diagnosis in high-risk patients.

Introduction

Brucellosis, caused by Brucella spp., is a zoonotic bacterial infection that spreads to people through direct contact with infected cattle, sheep, goats, or pigs, or through the consumption of unpasteurized animal products [1]. Undulant fever is the most common clinical manifestation, but progressive disease can also cause fatigue, anorexia, arthralgia, and myalgia. However, atypical presentations may result in misdiagnosis, inappropriate treatment, and poor therapeutic adherence, potentially leading to chronic infection, multi-organ damage, and significant patient economic burden [2]. We provide a case of brucellosis complicated by perinephritis, which manifested as abdominal and low back pain, to raise clinician awareness of diagnostic problems in atypical brucellosis presentation.

Case presentation

A 74-year-old male developed influenza-like symptoms followed by fever, lower back pain, and right abdominal pain on March 8, 2021. He first sought medical care at an outpatient clinic, where antibiotic treatment resolved the fever but exacerbated his back pain. On March 9, he was evaluated at Wuxiang people’s hospital, where an MRI confirmed lumbar disc herniation and a CT scan revealed perinephric inflammation (Fig. 1). Laboratory tests at that time were unremarkable. Although Qingkailing and celecoxib temporarily controlled the fever, his pain persisted.

Fig. 1.

Abdominal CT of the patient. Abdominal CT findings of the patient demonstrating perinephric fat stranding (white arrows) and bilateral anterior renal fascia thickening.

The patient was then referred to Shanxi Bethune Hospital for further management on March 16. Upon admission, gastrointestinal endoscopy and abdominopelvic CT were performed, which identified a gastric ulcer, colonic polyps, and renal cysts, with no evidence of malignancy. MRI and urinary ultrasonography only showed benign prostatic hyperplasia. Laboratory testing revealed elevated PSA (15.12 ng/mL), increased neutrophils (4.77 × 10⁹/L), and raised inflammatory markers (CRP 28.7 mg/L; ESR 38 mm/h). On March 19, he developed progressive anemia (Hb decreasing from 8.1 to 6.3 g/dL), recurrent fever (38.6℃), and severe abdominal pain (VAS 8), necessitating blood transfusion. On March 20, an epidemiological investigation uncovered a history of chronic consumption of unpasteurized sheep meat. The SAT result from March 21 showed a supportive but sub-threshold titer of 1:100 +. Definitive diagnosis was confirmed by the isolation of Brucella species from blood culture on March 23.

Treatment was initiated with intravenous ceftriaxone (2 g every 12 h), oral rifampin (450 mg once daily), intravenous etimicin (300 mg once daily), and oral doxycycline (100 mg twice daily) from March 23 to April 13. The patient’s symptoms resolved within 28 days, with pain reduced to VAS 3–4, and normalization of CRP (18.01 mg/L), ESR (18 mm/h), neutrophil count (3.79 × 10⁹/L), and hemoglobin (9.6 g/dL). He was discharged with instructions to complete a 6-week course of oral antibiotics.

Discussion

Brucellosis is a zoonotic disease caused by facultative intracellular Brucella species. In this case, the patient had a history of residing in an endemic region and probable exposure to unpasteurized dairy products—a well-established risk factor for infection [3]. The clinical presentation featured undulant fever, diaphoresis, and right lumbar pain, consistent with typical brucellosis manifestations [4].

Notably, this case illustrates an uncommon complication: brucellar perinephritis. Although perinephric abscess has been reported in brucellosis (Table 1), perinephritis remains a rarely documented complication of this infection. Limited epidemiological data exist regarding its incidence, and its potential association with renal tubular dysfunction requires further investigation [5]. The patient exhibited no evidence of spondylitis or abscess on lumber MRI and abdominal CT, which helped differentiate perinephritis from more common osteoarticular complications such as spondyloarthritis, which affects approximately 10–40 % of patients with complicated brucellosis [6]. Instead, right perinephric fat stranding was identified, suggesting localized inflammation without renal parenchymal invasion or abscess formation. Hematogenous spread or local extension from infected adjacent tissues (e.g., renal parenchyma) enables Brucella dissemination to the kidneys and peri-renal structures [7].

Table 1.

Renal or perinephric brucelloma cases reported in PubMed.

No.	Author (Year)	Age/Sex	Clinical Presentation	Diagnosis Method	Treatment	Outcome
1	KELALIS PP et al. (1967) [7]	72/F	Pain in the left flank and left lower quadrant of the abdomen	Exudate culture	Streptomycin dihydrostreptomycin combination and oxytetracycline	Cured
2	R.V. Jayakumar et al. (1988) [9]	29/F	High fever and right sided lumbar pain without urinary symptoms	Blood culture for brucella, brucella agglutination test, Ultrasound and CT scans	Anti-brucella treatment	Cured
3	Metin Onaranet al. (2005) [10]	36/M	Fever, arthralgias and back pain	Abdominal ultrasonography, CT and polymerase chain reaction (PCR) examination from the resected tissue	Sugrery combined with rifampicin and doxycycline	Cured
4	Jack Clarke et al. (2024) [11]	37/M	Lower back pain and fever	Abdomen CT and blood culture for brucella	Gentamicin, rifampicin and doxycycline	Cured

Diagnosis was ultimately confirmed by blood culture, which remains the gold standard [8]. Serological testing (SAT) was supportive but limited by the absence of paired samples, preventing demonstration of a fourfold titer increase. This underscores the importance of utilizing multiple diagnostic modalities in clinically suggestive cases, even when serology is inconclusive.

The patient was managed successfully with a combination of doxycycline and rifampin for 12 weeks—extended beyond the standard 6-week course due to concerns regarding deep-seated focal infection. This regimen aligned with CDC recommendations for complicated brucellosis [3], and resulted in complete symptomatic recovery and normalization of inflammatory markers.

In conclusion, this case highlights perinephritis as a rare but important differential diagnosis in brucellosis patients presenting with predominant lumbar pain. It underscores the value of advanced imaging to identify atypical foci of infection and demonstrates that extended antibiotic therapy, guided by concerns for deep-seated involvement, can yield excellent outcomes without the need for surgical intervention.

CRediT authorship contribution statement

Chen JianPing: Writing – review & editing. Xia Xu: Formal analysis. Zi-yang Li: Formal analysis. Xiang Gao: Investigation. Hang Li: Writing – review & editing, Writing – original draft.

Ethics Statement

Written informed consent was obtained from the individual for the publication of any potentially identifiable images or data included in this article.

Consent

Written informed consent was obtained from the individual for the publication of any potentially identifiable images or data included in this article.

Funding

This case did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Declaration of Competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.