STENOTROPHOMONAS MALTOPHİLİA BAKTERİYEMİSİNDE KLİNİK ÖZELLİKLER, TEDAVİ SONUÇLARI VE MORTALİTE İLE İLİŞKİLİ RİSK FAKTÖRLERİNİN ANALİZİ

Abstract

Amaç: Stenotrophomonas maltophilia doğal direnç mekanizmaları ve sınırlı tedavi seçenekleri nedeniyle önemli bir nozokomiyal patojen haline gelmiştir. Bu çalışma S. maltophilia bakteriyemisi olgularında antimikrobiyal duyarlılık paternlerini, klinik özellikleri ve mortaliteyle ilişkili faktörleri değerlendirmeyi amaçlamaktadır. Gereç ve Yöntemler: Bu retrospektif gözlemsel çalışmaya, 2020-2025 yılları arasında Erzurum Şehir Hastanesinde kan kültürlerinde Stenotrophomonas maltophilia izole edilen 18 yaş ve üzeri erişkin bireyler dâhil edilmiştir. Klinik veriler hastane kayıtlarından elde edilmiş; antimikrobiyal duyarlılık sonuçları ise European Committee on Antimicrobial Susceptibility Testing (EUCAST) ve Clinical and Laboratory Standards Institute (CLSI) standartlarına göre değerlendirilmiştir. Bulgular: Toplam 221 hastanın yaş ortalaması 64,6±20,3 yıl olup %53,3’ü erkekti. Mortalite oranı %34,8 olarak saptandı. Mortalite, ileri yaş, yoğun bakım yatışı (%93,5), komorbidite varlığı (%94,8) ve invaziv cihaz kullanımı ile anlamlı derecede yüksek bulunmuştur (p<0,001). Sepsis, mortal seyreden hastaların %75,3’ünde mevcuttu. Trimetoprim-sülfametoksazol direnci 2021 yılında %12,5 iken 2025 yılında %20’ye yükselmiş, buna karşılık levofloksasin direnci son yıllarda%33’ten %17-20 aralığına gerilemiştir. Seftazidim direnci yüksek düzeyde (% 48-51) seyrederken, tigesiklin direnci düşük oranlarda (%7-10) saptanmıştır. Sonuç: Trimetoprim-sülfametoksazol ve tigesiklin halen en etkili ajanlardır, ancak Trimetoprim-sülfametoksazol için artan direnç eğilimi dikkatle izlenmelidir. Yaş, komorbidite ve invaziv cihaz kullanımı mortaliteyi belirleyen temel faktörlerdir. Sürekli sürveyans ve akılcı antibiyotik politikaları, S. maltophilia bakteriyemisinde mortaliteyi azaltmada kritik öneme sahiptir.

Keywords

• Stenotrophomonas maltophilia
• bakteriyemi
• antibiyotik direnci
• mortalite
• yoğun bakım üniteleri

Supporting Institution

Çalışmada hiçbir kurum ya da kişiden finansal destek alınmamıştır.

Ethical Statement

Bu çalışma, Sağlık Bilimleri Üniversitesi Erzurum Tıp Fakültesi Bilimsel Araştırmalar Etik Kurulu tarafından onaylanmıştır (Karar No: 2025/05-141, Tarih: 14 Mayıs 2025).

Thanks

Antimikrobiyal duyarlılık testlerinin değerlendirilmesinde EUCAST ve CLSI standartlarının uygulanması sürecinde sağladığı teknik destek ve laboratuvar yönlendirmeleri nedeniyle Erzurum Şehir Hastanesi Mikrobiyoloji Laboratuvarı’ndan Uzman Doktor Yavuz Alper Sarı’ya teşekkür ederiz. Dr. Sarı, çalışmanın materyal-metot bölümünde kullanılan mikrobiyolojik yöntemlerin standardizasyonuna teknik düzeyde katkı sağlamış olup, yazarlık kriterlerini tam olarak karşılamadığı için teşekkür bölümünde anılmıştır.

Clinical Characteristics, Treatment Outcomes, and Mortality-Associated Risk Factors in Stenotrophomonas Maltophilia Bacteremia

Abstract

Objective: Stenotrophomonas maltophilia has become an important nosocomial pathogen due to its intrinsic resistance mechanisms and limited treatment options. This study aimed to evaluate antimicrobial susceptibility patterns, clinical characteristics, and factors associated with mortality in patients with S. maltophilia bacteremia. Material and Methods: This retrospective observational study included adult patients aged 18 years and older in whom Stenotrophomonas maltophilia was isolated from blood cultures at Erzurum City Hospital between 2020 and 2025. Clinical data were obtained from hospital records, and antimicrobial susceptibility results were evaluated according to the standards of the European Committee on Antimicrobial Susceptibility Testing (EUCAST) and the Clinical and Laboratory Standards Institute (CLSI). Results: A total of 221 patients were included, with a mean age of 64.6±20.3 years; 53.3% were male. The overall mortality rate was 34.8%. Mortality was significantly higher in patients with advanced age, intensive care unit admission (93.5%), presence of comorbidities (94.8%), and use of invasive devices (p<0.001). Sepsis was present in 75.3% of non-survivors. Trimethoprim–sulfamethoxazole resistance increased from 12.5% in 2021 to 20.0% in 2025, whereas levofloxacin resistance declined from 33% to 17–20% in recent years. Resistance to ceftazidime remained high (48–51%), while tigecycline resistance was low (7–10%). Conclusion: Trimethoprim–sulfamethoxazole and tigecycline remain the most effective agents; however, the increasing resistance trend to trimethoprim–sulfamethoxazole should be closely monitored. Age, comorbidities, and invasive device use are the main determinants of mortality. Continuous surveillance and rational antibiotic policies are critical for reducing mortality in S. maltophilia bacteremia.

Keywords

• Stenotrophomonas maltophilia
• bacteremia; antibiotic resistance
• mortality
• intensive care units

Supporting Institution

No financial support was received from any institution or individual for this study.

Ethical Statement

This study was approved by the Scientific Research Ethics Committee of the Erzurum Faculty of Medicine, University of Health Sciences (Decision No: 2025/05-141, Date: May 14, 2025).

Thanks

We would like to thank Specialist Dr. Yavuz Alper Sarı from the Microbiology Laboratory of Erzurum City Hospital for his technical support and laboratory guidance during the implementation of EUCAST and CLSI standards in the evaluation of antimicrobial susceptibility tests. Dr. Sarı provided technical contributions to the standardization of the microbiological methods used in the Materials and Methods section of the study but was acknowledged in the acknowledgments section as he did not fully meet the authorship criteria.

References

1. Kanchanasuwan S, Rongmuang J, Siripaitoon P, et al. Clinical characteristics, outcomes, and risk factors for mortality in patients with Stenotrophomonas maltophilia bacteremia. J Clin Med. 2022;11(11):3085.
2. Looney WJ, Narita M, Mühlemann K. Stenotrophomonas maltophilia: an emerging opportunist human pathogen. Lancet Infect Dis. 2009;9(5):312-323.
3. Wang WS, Liu CP, Lee CM, Huang FY. Stenotrophomonas maltophilia bacteremia in adults: four years' experience in a medical center in northern Taiwan. J Microbiol Immunol Infect. 2004;37(6):359-365.
4. Victor MA, Arpi M, Bruun B, Jønsson V, Hansen MM. Xanthomonas maltophilia bacteremia in immunocompromised hematological patients. Scand J Infect Dis. 1994;26(2):163-170.
5. Falagas ME, Kastoris AC, Vouloumanou EK, et al. Attributable mortality of Stenotrophomonas maltophilia infections: a systematic review of the literature. Future Microbiol. 2009;4(9):1103-1109.
6. Alonso A, Martinez JL. Multiple antibiotic resistance in Stenotrophomonas maltophilia. Antimicrob Agents Chemother. 1997;41(5):1140-1142.
7. Zhang L, Li XZ, Poole K. Multiple antibiotic resistance in Stenotrophomonas maltophilia: involvement of a multidrug efflux system. Antimicrob Agents Chemother. 2000;44(2):287-293.
8. Gajdács M, Urbán E. Prevalence and antibiotic resistance of Stenotrophomonas maltophilia in respiratory tract samples: a 10-year epidemiological snapshot. Health Serv Res Manag Epidemiol. 2019;6:2333392819870774.

9. Farrell DJ, Sader HS, Jones RN. Antimicrobial susceptibilities of a worldwide collection of Stenotrophomonas maltophilia isolates tested against tigecycline and agents commonly used for S. maltophilia infections. Antimicrob Agents Chemother. 2010;54(6):2735-2737.
10. Cho SY, Lee DG, Choi SM, et al. Stenotrophomonas maltophilia bloodstream infection in patients with hematologic malignancies: a retrospective study and in vitro activities of antimicrobial combinations. BMC Infect Dis. 2015;15:69.
11. Nicodemo AC, Paez JI. Antimicrobial therapy for Stenotrophomonas maltophilia infections. Eur J Clin Microbiol Infect Dis. 2007;26(4):229-237.
12. Brooke JS. Advances in the microbiology of Stenotrophomonas maltophilia. Clin Microbiol Rev. 2021;34(3):e0003019.
13. Ortiz-Gómez T, Toledano P, Gomez AC, et al. Phenotypic characteristics and clonal relationships of Stenotrophomonas maltophilia isolates in hospitalized adults from a private center in Lima, Peru. Infect Chemother. 2023;55(2):278-282.
14. Mermel LA, Allon M, Bouza E, et al. Clinical practice guidelines for the diagnosis and management of intravascular catheter-related infection: 2009 Update by the Infectious Diseases Society of America. Clin Infect Dis. 2009;49(1):1-45.
15. European Committee on Antimicrobial Susceptibility Testing (EUCAST). Breakpoint tables for interpretation of MICs and zone diameters version 12.0. Basel. EUCAST, 2022.
16. Fratoni AJ, Nicolau DP, Kuti JL. Levofloxacin pharmacodynamics against Stenotrophomonas maltophilia in a neutropenic murine thigh infection model: implications for susceptibility breakpoint revision. J Antimicrob Chemother. 2021;77(1):164-168.
17. Pierce VM, Bhowmick T, Simner PJ. Guiding antimicrobial stewardship through thoughtful antimicrobial susceptibility testing and reporting strategies: an updated approach in 2023. Journal of clinical microbiology. 2023;61(11):e00074-22.
18. Gibb J, Wong DW. Antimicrobial treatment strategies for Stenotrophomonas maltophilia: a focus on novel therapies. Antibiotics (Basel). 2021;10(10):1226.
19. Falagas ME, Kastoris AC, Vouloumanou EK, Dimopoulos G. Community-acquired Stenotrophomonas maltophilia infections: a systematic review. Eur J Clin Microbiol Infect Dis. 2009;28(7):719-730.
20. Looney WJ, Narita M, Mühlemann K. Stenotrophomonas maltophilia: an emerging opportunist human pathogen. Lancet Infect Dis. 2009;9(5):312-323.
21. Alonso A, Martínez JL. Multiple antibiotic resistance in Stenotrophomonas maltophilia. Antimicrob Agents Chemother. 1997;41(5):1140-1142.
22. Duan Z, Qin J, Li C, Ying C. Clinical and molecular epidemiology of Stenotrophomonas maltophilia in pediatric patients from a Chinese teaching hospital. Front Cell Infect Microbiol. 2020;10:411.
23. Bilgin M, İşler H, Başbulut E, Yılmaz EM. Stenotrophomonas maltophilia klinik suşlarında antimikrobiyal direnç: 10 yıllık sürveyans. ANKEM Dergisi. 2022;36(1):16-22.
24. Dönmez B, Yılmaz Ş, Başar E. Çeşitli klinik örneklerden elde edilen Stenotrophomonas maltophilia izolatlarının dağılımı ve antibiyotik duyarlılık profili. ANKEM Dergisi. 2025;39(1):7-13.
25. Hasbek M, Aldemir Ö, Çakır Kıymaz Y, et al. Mortality rates and risk factors associated with mortality in patients with Stenotrophomonas maltophilia primary bacteraemia and pneumonia. Diagn Microbiol Infect Dis. 2025;111(3):116664.
26. Cho SY, Kang CI, Kim J, et al. Can levofloxacin be a useful alternative to trimethoprim-sulfamethoxazole for treating Stenotrophomonas maltophilia bacteremia? Antimicrob Agents Chemother. 2014;58(1):581-583.
27. Hotta G, Matsumura Y, Kato K, et al. Risk factors and outcomes of Stenotrophomonas maltophilia bacteraemia: a comparison with bacteraemia caused by Pseudomonas aeruginosa and Acinetobacter species. PLoS One. 2014;9(11):e112208.
28. Garazi M, Singer C, Tai J, Ginocchio CC. Bloodstream infections caused by Stenotrophomonas maltophilia: a seven-year review. J Hosp Infect. 2012;81(2):114-118.
29. Hazirolan G, Araz H, Çelikbaş AK, Aksu N. Dikkat! Klinik örneklerden izole edilen Stenotrophomonas maltophilia suşlarının trimetoprim-sülfametoksazol ve levofloksasin direncinde belirgin artış var (2008-2016). Türk Mikrobiyol Cem Derg. 2018;48(2):134-140.
30. Kandemir İ, Özcan N, Alanbayı Ü, et al. Klinik örneklerden izole edilen Stenotrophomonas maltophilia suşlarının dağılımı ve antimikrobiyal duyarlılıkları. Dicle Tıp Derg. 2016;43(2):237-240.
31. Şen P, Yula E, Er H, et al. Çeşitli klinik örneklerden izole edilen Stenotrophomonas maltophilia suşlarında antibiyotiklere direnç oranı. Ortadoğu Tıp Derg. 2017;9(3):113-117.
32. AlFonaisan MK, Mubaraki MA, Althawadi SI, et al. Temporal analysis of prevalence and antibiotic-resistance patterns in Stenotrophomonas maltophilia clinical isolates in a 19-year retrospective study. Sci Rep. 2024;14(1):14459.
33. Aslan GK, Esenkaya Taşbent F, Doğan M. Sınırlı antibiyotik seçeneği olan Stenotrophomonas maltophilia enfeksiyonlarında antibiyotik direnç profili. Türk Mikrobiyol Cem Derg. 2021;51(4):334-340.
34. Zer Y, Karaoğlan İ, Çevik S, Erdem M. Stenotrophomonas maltophilia suşlarının antibiyotik duyarlılıklarının irdelenmesi. Klimik Derg. 2009;22(1):21-24.
35. Banar M, Sattari-Maraji A, Bayatinejad G, et al. Global prevalence and antibiotic resistance in clinical isolates of Stenotrophomonas maltophilia: a systematic review and meta-analysis. Front Med (Lausanne). 2023;10:1163439.
36. Biagi M, Tan X, Wu T, et al. Activity of potential alternative treatment agents for Stenotrophomonas maltophilia isolates nonsusceptible to levofloxacin and/or trimethoprim-sulfamethoxazole. J Clin Microbiol. 2020;58(2):e01603-19.
37. Su BA, Chen CC, Chen HJ, et al. In vitro activities of antimicrobial combinations against planktonic and biofilm forms of Stenotrophomonas maltophilia. Front Microbiol. 2023;14:1186669.
38. Oyardı Ö, Altunboğa G, Olcay FN, Erturan Z. Efficacy of aztreonam/avibactam against Stenotrophomonas maltophilia alone and in combination with tigecycline. Istanbul J Pharm. 2024;54(3):395-402.