Sequential Serratia liquefaciens and Serratia odorifera Pneumonia in an Elderly Patient with ARDS and Septic Shock: A Case Report
Keywords:
ARDS, nosocomial pneumonia, Serratia liquefaciens, Serratia odorifera, antibiotic stewardship, elderly, ICU, tracheostomy, supraventricular tachycardia, AmpC β-lactamase, sepsisAbstract
Background:
Acute respiratory distress syndrome (ARDS) in the elderly is frequently precipitated by nosocomial pneumonia and complicated by sepsis and cardiac comorbidity. While Serratia marcescens is a recognized pathogen, pneumonia due to non-marcescens Serratia (e.g., S. liquefaciens, S. odorifera) is exceptionally rare. Antimicrobial stewardship—with early broad empiric therapy followed by de-escalation—may reshape respiratory microbiology during prolonged ICU care.
Case Presentation:
A 78-year-old man with hypertension and remote pulmonary tuberculosis presented with 3 days of progressive dyspnea and epigastric chest pain radiating to the right arm, plus diaphoresis. On arrival: RR 42/min, HR 105/min, BP 50/30 mmHg, SpO₂ 57% (room air). Chest radiographs showed bilateral alveolar infiltrates; he was intubated and ventilated (PSIMV, FiO₂ 100%, PEEP 5 cmH₂O) with persistent severe hypoxemia consistent with ARDS. Initial labs revealed leukocytosis, elevated CRP, D-dimer 430 ng/mL FEU, anemia, hypokalemia, and variable glycemia; ionized calcium was repeatedly low (0.97–1.05 mmol/L). He developed recurrent SVT with RBBB (rates up to ~200 bpm) requiring amiodarone and bisoprolol. Empiric meropenem (1 g IV q8h) was started. Sputum culture on day 2 grew Serratia liquefaciens. Following antimicrobial adjustment, a repeat culture on day 7 yielded S. odorifera with an AmpC-like resistance pattern (non-susceptible to early-generation cephalosporins/aminopenicillins; susceptible to cefepime / carbapenem / fluoroquinolone / TMP-SMX).Therapy was tailored to levofloxacin 750 mg IV daily plus cefoperazone 1 g IV q12h. Blood cultures remained negative; GeneXpert MTB/RIF was negative. Tracheostomy on ICU day 5 enabled weaning (PSV→CPAP→T-piece 10→5 L/min) with SpO₂ 96–99%. Doppler later showed right popliteal artery stenosis; heparin was escalated to therapeutic dosing. By ICU day 14, he was clinically improved and transferred to the ward.
Conclusion:
This case illustrates sequential pneumonia due to two rare non-marcescens Serratia species in severe ARDS, emphasizing careful microbiologic reassessment during stewardship-driven therapy and the value of targeted antibiotics plus multidisciplinary ICU care.
References
Ranieri VM, Rubenfeld GD, Thompson BT, Ferguson ND, Caldwell E, Fan E, et al. Acute respiratory distress syndrome: the Berlin Definition. JAMA. 2012;307(23):2526-33. doi:10.1001/jama.2012.5669. Available from: https://jamanetwork.com/journals/jama/fullarticle/1160659 JAMA Network
Kalil AC, Metersky ML, Klompas M, Muscedere J, Sweeney DA, Palmer LB, et al. Management of adults with hospital-acquired and ventilator-associated pneumonia: 2016 clinical practice guidelines by IDSA and ATS. Clin Infect Dis. 2016;63(5):e61-111. doi:10.1093/cid/ciw353. Available from: https://academic.oup.com/cid/article/63/5/e61/2237650; guideline page: https://www.idsociety.org/practice-guideline/hap_vap/ OUP Academic+1
Lee J, Carey J, Perlman DC. Pneumonia and bacteremia due to Serratia odorifera. J Infect. 2006;53(3):212-4. doi:10.1016/j.jinf.2005.11.016. Available from: https://pubmed.ncbi.nlm.nih.gov/16403578/; article page: https://www.journalofinfection.com/article/S0163-4453(05)00380-4/abstract PubMed+1
Harnett SJ, Allen KD, Macmillan RR. Critical care unit outbreak of Serratia liquefaciens from contaminated pressure monitoring equipment. J Hosp Infect. 2001;47(4):301-7. doi:10.1053/jhin.2001.0941. Available from: https://pubmed.ncbi.nlm.nih.gov/11289774/; full text: https://www.journalofhospitalinfection.com/article/S0195-6701(01)90941-7/fulltext PubMed+1
Mahlen SD. Serratia infections: from military experiments to current practice. Clin Microbiol Rev. 2011;24(4):755-91. doi:10.1128/CMR.00017-11. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC3194826/; journal page: https://journals.asm.org/doi/10.1128/cmr.00017-11 PMC+1
Williams CL, Neuhauser S, Orth-Han S, et al. The genus Serratia revisited by genomics. Commun Biol. 2022;5:840. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC9440931/ (context on species diversity/clinical relevance). PMC
Tabah A, Bassetti M, Kollef MH, Zahar JR, Paiva JA, Timsit J-F, et al. Antimicrobial de-escalation in critically ill patients: a position statement from ESICM/ESCMID (ESGCIP). Intensive Care Med. 2020;46(2):245-65. doi:10.1007/s00134-019-05866-w. Available from: https://anesthesia.gr/wp-content/uploads/2022/05/Antimicrobial-de-escalation-in-critically-ill-patients-a-position-statement-ESCMID-ESICM-2019.pdf; PubMed: https://pubmed.ncbi.nlm.nih.gov/31781835/ anesthesia.gr+1
De Bus L, Depuydt P, Steen J, Dhaese S, De Waele JJ, et al. Antimicrobial de-escalation in the critically ill patient and assessment of clinical cure: the DIANA study. Intensive Care Med. 2020;46(7):1404-17. doi:10.1007/s00134-020-06111-5. Available from: https://link.springer.com/article/10.1007/s00134-020-06111-5; PubMed: https://pubmed.ncbi.nlm.nih.gov/32519003/ SpringerLink+1
Schouten, L.R.A., Bos, L.D.J., Serpa Neto, A. et al. Increased mortality in elderly patients with acute respiratory distress syndrome is not explained by host response. ICMx 7, 58 (2019). https://doi.org/10.1186/s40635-019-0270-1
Ho S. Outcomes of elderly and very elderly patients admitted to ICU for sepsis. Eur Respir J. 2022;60(Suppl 66):2583. doi:10.1183/13993003.congress-2022.2583. Available from: https://publications.ersnet.org/content/erj/60/suppl66/2583
Ibarz M, Haas LEM, Ceccato A, Artigas A, et al. The critically ill older patient with sepsis: a narrative review. Ann Intensive Care. 2024;14:6. doi:10.1186/s13613-023-01233-7. Available from: https://annalsofintensivecare.springeropen.com/articles/10.1186/s13613-023-01233-7
Patel PK. Serratia: Background, Pathophysiology, Epidemiology. Medscape. Updated Dec 13, 2024. Available from: https://emedicine.medscape.com/article/228495-overview
Almendra AMC da Silva, Barbosa J, Organista D, Carvalho C, Abreu T, Mota L, Semedo J, Bárbara C. Atypical Pneumonia in Patient with Serratia odorifera: A Rare Association. Clin Image Case Rep J. 2021;3(2):139. Available from: https://www.literaturepublishers.org/archive/Atypical-Pneumonia-in-Patient-with-Serratia-odorifera%3A-A-Rare-Association.html
Singh P, Pandey A. Community-acquired lower respiratory tract infection due to Serratia rubidaea: A rare and opportunistic pathogen. MRIMS J Health Sci. 2025;13(1):35–38. doi:10.4103/mjhs.mjhs_61_24. Available from: https://journals.lww.com/mjhs/fulltext/2025/01000/community_acquired_lower_respiratory_tract.8.aspx
Lee J, Carey J, Perlman DC. Pneumonia and bacteremia due to Serratia odorifera. J Infect. 2006;53(3):212-214. doi:10.1016/j.jinf.2005.11.016. Available from: https://www.journalofinfection.com/article/S0163-4453(05)00380-4/abstract
Serratia liquefaciens – an overview. ScienceDirect Topics. Available from: https://www.sciencedirect.com/topics/medicine-and-dentistry/serratia-liquefaciens
Saint-Pierre M, et al. Serratia liquefaciens respiratory infection likely related to home brewing of kombucha. Am J Respir Crit Care Med (ATS meeting abstract). 2020;201(1):A3896. doi:10.1164/ajrccm-conference.2020.201.1_MeetingAbstracts.A3896. Available from: https://www.atsjournals.org/doi/abs/10.1164/ajrccm-conference.2020.201.1_MeetingAbstracts.A3896?download=true
Serratia marcescens: Bacteria, Infection, Causes & Treatment.” Cleveland Clinic. 2025 Apr 8 [cited 2025 Oct 14]. Available from: https://my.clevelandclinic.org/health/diseases/serratia-marcescens
Hammond V. Auxiliary Label: Antibiotic stewardship research in a community outpatient setting. VCU School of Pharmacy News Archive. 7 Nov 2018 [cited 2025 Oct 14]. Available from: https://blogs.vcu.edu/pharmacy/2018/11/auxiliary-label-antibiotic-stewardship-research-in-a-community-outpatient-setting/
Singh P, Pandey A. Opportunistic Community Acquired Pneumonia Due to Rare Pathogen Serratia plymuthica. Med J Dr DY Patil Univ. 2025;18(2):352-355. doi:10.4103/mjdrdypu.mjdrdypu_145_24. Available from: https://journals.lww.com/mjdy/fulltext/2025/03000/opportunistic_community_acquired_pneumonia_due_to.30.aspx
Zarogoulidis P, Porpodis K, Konoglou M, Saroglou M, Mitrakas A, Matthaios D, Touzopoulos P, Archontogeorgis K, Koulelidis A, Zarogoulidis K, Tryfon S. Serratia pneumonia presenting as hemoptysis in a patient with sarcoidosis: a case report. Int J Gen Med. 2011;4:661-4. doi: 10.2147/IJGM.S24706. Epub 2011 Sep 8. PMID: 21941452; PMCID: PMC3177592.
Ramos JM, Peláez T, García M, et al. Serratia bacteremia in a large university hospital: trends in antibiotic resistance during 10 years and implications for antibiotic use. Infect Control Hosp Epidemiol. 2006;27(10):1138-1143. doi:10.1086/507551. Available from: https://www.cambridge.org/core/journals/infection-control-and-hospital-epidemiology/article/abs/serratia-bacteremia-in-a-large-university-hospital-trends-in-antibiotic-resistance-during-10-years-and-implications-for-antibiotic-use/9A1A6A97917E8F0CD542F2928A01B629
Dellinger RP, Levy MM, Rhodes A, Annane D, Gerlach H, Opal SM, et al. Surviving Sepsis Campaign: international guidelines for management of severe sepsis and septic shock, 2012. Crit Care Med. 2013;41(2):580–637. doi:10.1097/CCM.0b013e31827e83af. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4296551/
Liu Y-W, Wang Y-F, Chen Y, Dong R, Li S, Peng J-M, et al. A nationwide study on new onset atrial fibrillation risk factors and its association with hospital mortality in sepsis patients. Sci Rep. 2024;14:12206. doi:10.1038/s41598-024-62630-x. Available from: https://www.nature.com/articles/s41598-024-62630-x
Vincent JL, Moreno R, Takala J, Willatts S, De Mendonça A, Bruining H, et al. The SOFA (Sepsis-related Organ Failure Assessment) score to describe organ dysfunction/failure. Intensive Care Med. 1996;22(7):707–710. doi:10.1007/s001340050900. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3301032/
Zaloga GP, Chernow B. The multifactorial basis for hypocalcemia during sepsis: Studies of the parathyroid hormone-vitamin D axis. Ann Intern Med. 1987;107(1):36-41. doi:10.7326/0003-4819-107-1-36. Available from: https://pubmed.ncbi.nlm.nih.gov/3592447/
Melchers M, van Zanten ARH. Management of hypocalcaemia in the critically ill. Curr Opin Crit Care. 2023;29(4):330-338. doi:10.1097/MCC.0000000000001059. Available from: https://journals.lww.com/co-criticalcare/fulltext/2023/08000/management_of_hypocalcaemia_in_the_critically_ill.8.aspx
Li, X., Zhang, D., Chen, Y. et al. Acute glycemic variability and risk of mortality in patients with sepsis: a meta-analysis. Diabetol Metab Syndr 14, 59 (2022). https://doi.org/10.1186/s13098-022-00819-8
Prakash P, Sethi P, Vikram N, Khan M, Gupta Y, Jadon RS, Kumar A, Meena VP, Wig N. Association of Glycemic Variability with Outcomes in Non-diabetic Sepsis Patients: A Prospective Observational Study. Indian J Crit Care Med. 2025 Jan;29(1):27-35. doi: 10.5005/jp-journals-10071-24873. Epub 2024 Dec 30. PMID: 39802255; PMCID: PMC11719557.
Yadagudde SP, Jayasenan J, Srinivasagalu K. Glycaemic variability and its outcome in intensive care unit patients with sepsis. J West Afr Coll Surg. 2025;~(9900):—. doi:10.4103/jwas.jwas_149_24. Available from: https://journals.lww.com/jwas/fulltext/9900/glycaemic_variability_and_its_outcome_in_intensive.101.aspx
Downloads
Published
Issue
Section
License
Copyright (c) 2026 Aditya Kafi Amrullah, Syarifuddin, Reza Gusni S (Author)
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
