dawnmedDawnMed Journal of Medical ScienceISVolume 2, Issue 3MultidisciplinaryEnglish2026NNY20260811Infectious DiseasesShewanella algae Pneumonia and Bacteremia After Inland Sulfur-Water Exposure with Concurrent Parainfluenza Virus 3 Infection: A Case ReportEnglishY3439Lamia F.Albalawi¹EnglishNAhmad M.Alridahie²EnglishYShahad M.Albalawi³˒⁴EnglishYAmal A.Alhayek⁵EnglishYHassan A.Alsulaiman⁶EnglishYMohammed H.Alamer⁶EnglishYTariqAlrasheed¹EnglishY10.64039/djms.2026.2204Background: Shewanella algae is a halophilic, oxidase-positive, non-fermenting Gram-negative bacillus distributed in marine and other aquatic environments. It is an uncommon opportunistic human pathogen, most often causing skin and soft-tissue infection, hepatobiliary infection, and bacteremia, and is classically associated with marine or estuarine exposure. Respiratory involvement is rare.Case Presentation:A 67-year-old man with primary Sjögren syndrome maintained on long-term hydroxychloroquine and prednisolone, and usual interstitial pneumonia (UIP)-pattern interstitial lung disease, presented with a one-day history of productive cough, fever to 39 °C, rigors, and fatigue. He was febrile, tachycardic, tachypneic, and hypotensive, requiring 1 L/min of supplemental oxygen. Investigations showed a neutrophilic leukocytosis (white cell count 16.10 ×10⁹/L), C-reactive protein 89.90 mg/L, and procalcitonin 1.08 ng/mL. CT pulmonary angiography excluded pulmonary embolism and demonstrated new bilateral lower-lobe consolidation and ground-glass opacity superimposed on known interstitial lung disease. A multiplex respiratory panel detected parainfluenza virus 3 (PIV-3). Blood cultures grew Shewanella algae, which was resistant to meropenem, intermediate to piperacillin-tazobactam, and susceptible to ceftazidime, ciprofloxacin, and trimethoprim-sulfamethoxazole. A directed exposure history, obtained only after the organism was identified, revealed recent swimming in an inland sulfur-rich spring near Al-Kharj, Saudi Arabia. Empirical ceftriaxone and azithromycin were changed to intravenous piperacillin-tazobactam for 14 days, followed by oral trimethoprim-sulfamethoxazole for 14 days. The patient improved clinically, with resolution of the leukocytosis.Conclusion:S. algae should be considered in community-acquired pneumonia with bacteremia following recreational water exposure, including inland, non-marine sources such as sulfur springs. To our knowledge, this is the first report of S. algae respiratory infection and bacteremia occurring with concurrent PIV-3. In a host with structural lung disease and chronic immunomodulatory therapy, a targeted water-exposure history can point to the diagnosis, and the carbapenem resistance found here supports susceptibility-guided therapy.EnglishShewanella algae, bacteremia, sulfur spring, community-acquired pneumoniahttps://dawnmed.com.sa/abstract?id=26References1619Yu K, Huang Z, Xiao Y, Wang D. Shewanella infection in humans: epidemiology, clinical features and pathogenicity. Virulence. 2022;13(1):1515and;ndash;1532.Ng WWS, Shum HP, To KKW, Sridhar S. Emerging infections due to Shewanella spp.: a case series of 128 cases over 10 years. Front Med (Lausanne). 2022;9:850938.Weiss TJ, Barranco-Trabi JJ, Brown A, Oommen TT, Mank V, Ryan C. Shewanella algae pneumonia and bacteremia in an elderly male living at a long-term care facility. Am J Trop Med Hyg. 2022;106(1):60and;ndash;61.Chen J, Ling D, Wang F, Liu L, Ren Y, Chen C, et al. Septic shock caused by coinfection of Shewanella algae bloodstream infection and Epsteinand;ndash;Barr virus: clinical characteristics and genomic analysis. MicrobiologyOpen. 2026;15(1):e70221.Russell E, Yang A, Tardrew S, Ison MG. Parainfluenza virus in hospitalized adults: a 7-year retrospective study. Clin Infect Dis. 2019;68(2):298and;ndash;305.Holt HM, Gahrn-Hansen B, Bruun B. Shewanella algae and Shewanella putrefaciens: clinical and microbiological characteristics. Clin Microbiol Infect. 2005;11(5):347and;ndash;352.Naidoo S, Zwane AM, Paruk A, Hardcastle TC. Diagnosis and management of severe water-related skin and soft tissue sepsis: a summative review of the literature. Diagnostics (Basel). 2023;13(13):2150.Yousfi K, Bekal S, Usongo V, Touati A. Current trends of human infections and antibiotic resistance of the genus Shewanella. Eur J Clin Microbiol Infect Dis. 2017;36(8):1353and;ndash;1362.