Unusual Pathogens from Unusual Sites: A Case of Multifocal Sternoclavicular Septic Arthritis Isolating Salmonella Paratyphi B

RESEARCH ARTICLE Br J Med Health Res. 2025;12( 10 ) ISSN: 2394 - 2967 Please cite this article as: Karyakarte A et al., Unusual Pathogens from Unusual Sites: A Case of Multifocal Sternoclavicular Septic Arthritis Isolating Salmonella Paratyphi B. British Journal of Medical and Health Research 20 25 . BJMHR British Journal of Medical and Health Research Journal home page: www.bjmhr.com Unusual Pathogens from Unusual Sites: A Case of Multifocal Sternoclavicular Septic Arthritis Isolating Salmonella Paratyphi B Akshay Karyakarte1*, Rhea Solanke1, Lona Dash1, Chaya A. Kumar1 1. Department of Microbiology, Seth GS Medical College and KEM Hospital, Mumbai ABSTRACT Septic arthritis of the sternoclavicular joint is usually caused by Gram-positive cocci, and accounts for under 1% of orthopedic infections. Gram-negative organisms, especially those by Salmonella sp. are particularly rare. This report follows the case of a 42-year-old lady presenting with MRI-confirmed multifocal infective arthritis extending to the pectoralis major. Joint aspirate yielded Salmonella Group B, and a prior Widal test suggested Salmonella Paratyphi B exposure. Targeted specific antibiotic therapy resolved the patient’s symptoms. This case highlights the importance of comprehensive bacteriological workup in atypical cases, and the efficacy of early and culture-guided treatment in rare infections, to prevent complications. Keywords: Septic Arthritis, Immunocompromised host, Salmonella infections *Corresponding Author Email: [email protected] Received 02 September 2025, Accepted 05 October 2025 www.bjmhr.com 2 Karyakarte et. al., Br J Med Health Res. 2025;12(10) ISSN: 2394-2967 INTRODUCTION A] Background: Septic arthritis accounts for up to 15% of orthopedic infections, typically affecting large, weight-bearing joints. Septic arthritis of the sternoclavicular joint, however, is extremely rare and comprises less than 1% of the cases. [1] While Gram-positive cocci are the most common cause, infections with Gram-negative organisms have also been reported. [2] Septic arthritis caused by Salmonella species is particularly uncommon. This is a rare case of sternoclavicular septic arthritis caused by Salmonella Paratyphi B. B] Case History: A 42-year-old lady presented with a two-week history of progressive pain and swelling in the right upper chest, and decreased range of motion in her right arm. On examination, tenderness and swelling were noted at the right sternoclavicular joint, extending to the right anterior chest wall. The patient is a known case of diabetes mellitus, on treatment for the last 20 years. Magnetic Resonance Imaging revealed multifocal infective arthritis of the right sternoclavicular joint extending onto the right Pectoralis major (Figure 1). Joint exudate was aspirated under ultrasonic guidance; culture and sensitivity was requested. MATERIALS AND METHOD Primary Gram’s-stained smear of the USG-guided aspirate showed a few pus cells and Gramnegative bacilli. The sample was cultured on 5% Sheep’s Blood Agar, and MacConkey’s Agar, with overnight aerobic incubation at 37ºC. Pure growth was obtained on both media, showing non-hemolytic colonies on 5% Sheep’s Blood Agar, and non-lactose-fermenting colonies on MacConkey’s Agar (Figure 2). The isolate was oxidase negative, catalase positive, actively motile, and culture smear showed Gram-negative bacilli. Routine biochemical reactions for Gram-negative bacilli were put up (Table). Findings of culture, microscopy, and biochemical reactions enabled the identification of Group B Salmonella. Antibiotic susceptibility testing was performed using Kirby Bauer Disk Diffusion Method, and breakpoints interpreted by CLSI 2025 standards.[3] The isolate was susceptible to Ceftriaxone, Ciprofloxacin, Ampicillin, and Co-trimoxazole. Automated Identification and Antibiotic susceptibility testing with VITEK 2 Compact ID/AST system, and VITEK MS Prime (bioMérieux, France) yielded Salmonella enterica subspecies enterica; susceptible to the same antibiotics. Blood, urine, and stool cultures were obtained subsequently, which were negative for Salmonella. The isolate showed agglutination with Salmonella O4 antisera. The patient had undergone Widal test a month before presenting to this institution; it was positive for www.bjmhr.com 3 Karyakarte et. al., Br J Med Health Res. 2025;12(10) ISSN: 2394-2967 Salmonella Paratyphi B(H) which agglutinated at a dilution of 1:320. There was no record of blood culture or prescription of antibiotics at that time. FIGURE Table 1: Showing the biochemical reactions of the isolate Test Result Indole Production Produced Methyl Red Test Negative Voges Proskauer Test Positive Citrate Utilization Utilized Urease Production Not Produced TSI Agar K/A with gas and abundant H 2 S Lysine Decarboxylase Decarboxylated Ornithine Decarboxylase Not Decarboxylated Arginine Dihydrolase Not Di - Hydrolyzed Agglutination with O4 antiserum Agglutination seen Final Identification: Salmonella enterica subspecies enterica serogroup 4 (Group B) RESULTS AND DISCUSSION Patient outcome: A diabetic lady presenting with MRI-confirmed multifocal infective arthritis extending to the pectoralis major. Joint aspirate yielded Salmonella Group B, and a prior Widal test suggested Salmonella Paratyphi B exposure. The isolate was susceptible to Ceftriaxone, Ciprofloxacin, Ampicillin, Co-trimoxazole. The patient was administered Ceftriaxone and Ciprofloxacin, to which she responded favorably, with resolution of clinical symptoms. Typhoidal Salmonellae primarily cause enteric fever, although it can invade the intestinal mucosa and enter the bloodstream via lymphatic channels. Joint seeding of Salmonella is www.bjmhr.com 4 Karyakarte et. al., Br J Med Health Res. 2025;12(10) ISSN: 2394-2967 relatively rare, but is known to cause septic arthritis, especially affecting large, weightbearing joints. Salmonella infections in the sternoclavicular joint are even rarer, and are typically associated with immunocompromised states, or predisposing factors like diabetes and malignancies. [1], [4], [5] This patient had multifocal septic arthritis in the right sternoclavicular joint, with soft-tissue invasion. The positive Widal test for Salmonella Paratyphi B(H) at the significant dilution of 1:320 indicates the probability of exposure with Salmonella Paratyphi B. The lack of evidence of antibiotic therapy upon the positive Widal test could explain the subsequent seeding of the isolate into the sternoclavicular joint, however, the lack of records for blood cultures from that time hampered the definitive diagnosis as such. As the bacteriological workup in the present case yielded Salmonella enterica subspecies enterica serogroup 4 (Group B), and the kit used for Widal test in this patient utilized Phase I H-antigen ‘b’ (as mentioned on her past Widal report), a deductive identification of the isolate as Salmonella Paratyphi B was made. This case underscores the importance of culture and sensitivity testing, as empirical therapy often overlooks rare pathogens, which may lead to treatment failures if not detected early. [5] Favorable response to antibiotic therapy emphasizes the importance of early targeted therapy based on culture and sensitivity testing. This is particularly essential, as treatment failure may lead to severe complications like osteomyelitis or joint destruction. The case also highlights the continued importance of conventional tests like Widal, which in this case, enabled a deductive serotype-level identification. CONCLUSION This case reiterates that comprehensive bacteriological evaluation should be a cornerstone of management for atypical presentations of septic arthritis, which ensures that unusual pathogens are accurately identified and effectively treated, which in turn, would prevent complications and sequelae. DECLARATION:  The authors declare no conflict of interest in the present study  The patient consented for submission of this case report for publication  The authors have no competing interests to declare  No funding was received for this article REFERENCES 1. Shirtliff ME, Mader JT. Acute septic arthritis. Clin Microbiol Rev. 2002;15(4):52744. www.bjmhr.com 5 Karyakarte et. al., Br J Med Health Res. 2025;12(10) ISSN: 2394-2967 2. Darley ES, MacGowan AP. Antibiotic treatment of gram-positive bone and joint infections. J Antimicrob Chemother. 2004;53(6):928-35. 3. CLSI. Performance Standards for Antimicrobial Susceptibility Testing 35th ed. CLSI supplement M100. Lewis JS, et al: clinical and laboratory standards institute; 2025. 4. Tobón GJ, Garcia-Robledo JE, Nieto-Aristizábal I. Salmonella arthritis. In Infections and the Rheumatic Diseases 2019 Sep 27 (pp. 41-47). Cham: Springer International Publishing. 5. Butler BA, Fitz DW, Lawton CD, Li DD, Balderama ES, Stover MD. Early diagnosis of septic arthritis in immunocompromised patients. J. Orthop. Sci. 2018;23(3):542545 BJMHR is  Peer reviewed  Monthly  Rapid publication  Submit your next manuscript at [email protected]