The Activities of Antimicrobials Against Stenotrophomonas maltophilia Isolates and Evaluation of Clinical Outcomes Among Treatment Regimens in Patients with Stenotrophomonas maltophilia Infections: A Retrospective Multicenter Cohort Study

Patchrapa Boonmee,1,2 Worapong Nasomsong,3 Narisorn Lorchirachoonkul,4 Supanun Pungcharoenkijkul,5 Piraporn Juntanawiwat,6 Suphatthra Chaemchaeng,7 Wichai Santimaleeworagun8,9 1College of Pharmacotherapy Thailand, Nonthaburi, Thailand; 2Department of Pharmacy, Ratchaburi Hospital, Ratchaburi, Thailand; 3Division of Infectious Diseases, Department of Internal Medicine, Phramongkutklao Hospital and College of Medicine, Bangkok, Thailand; 4Department of Medicine, Ratchaburi Hospital, Ratchaburi, Thailand; 5Pharmacy Unit, Nopparat Rajathanee Hospital, Bangkok, Thailand; 6Division of Microbiology, Phramongkutklao Hospital, Bangkok, Thailand; 7Division of Microbiology, Ratchaburi Hospital, Ratchaburi, Thailand; 8Department of Pharmaceutical Care, Faculty of Pharmacy, Silpakorn University, Nakorn Pathom, Thailand; 9Pharmaceutical Initiative for Resistant Bacteria and Infectious Disease Working Group (PIRBIG), Nakorn Pathom, ThailandCorrespondence: Wichai Santimaleeworagun, Department of Pharmaceutical Care, Faculty of Pharmacy, Silpakorn University, Nakorn Pathom, 73000, Thailand, Tel +66 3 425 5800, Fax +66 3 425 5801, Email swichai1234@gmail.comPurpose: Stenotrophomonas maltophilia, a multidrug-resistant pathogen can cause hospital-acquired infections such as pneumonia, or bloodstream infection. S. maltophilia infection is associated with high mortality rates. This retrospective study examined the antimicrobial susceptibility profile of clinical S. maltophilia isolates and evaluated clinical outcomes, treatment regimens, and risk factors associated with 30-day mortality or treatment failure of S. maltophilia infections at three tertiary care hospitals in Central Thailand.Patients and Methods: The characteristics, microbiological data, and clinical treatment outcomes were derived from medical records obtained from three tertiary care hospitals in Central Thailand from January 2017 to October 2022. The primary outcomes were treatment failure and 30-day mortality. The antimicrobial susceptibility rates of trimethoprim-sulfamethoxazole (TMP-SMX), levofloxacin, and ceftazidime were determined by minimum inhibitory concentration (MIC), which were based on broth microdilution and clear zone diameters using the disk diffusion method. However, we also report the susceptibility of minocycline and tigecycline in some clinical S. maltophilia strains (n = 149) and determined by MIC with E-test method.Results: The antimicrobial susceptibility rates to TMP-SMX, levofloxacin, and ceftazidime were 97.1%, 93%, and 55.3%, respectively. The treatment failure rate and 30-day mortality were 66.3% and 49%, respectively. Significant factors associated with treatment failure included APACHE II score ≥ 15 (OR 3.37, 95% confidence interval (CI) 1.46– 7.76), polymicrobial infections (OR 3.20, 95% CI 1.35– 7.55). The significant factors associated with reduced treatment failure was treatment with TMP-SMX-based regimen (OR 0.29, 95% CI 0.11– 0.76). The 30-day mortality rate was associated with APACHE II score ≥ 15 (OR 3.27, 95% CI 1.45– 7.39) and septic shock (OR 2.53, 95% CI 1.36– 4.69).Conclusion: The results indicate a high mortality rate for S. maltophilia infection. The predictive factors for an unfavourable outcome were severity of illness, septic shock, and non-use of TMP-SMX. Therefore, a TMP-SMX-based regimen is recommended for the treatment of S. maltophilia infections.Keywords: co-trimoxazole, levofloxacin, mortality, Xanthomonas

Topic: Vector-borne infectious diseases
Subfield: Parasitology
Field: Immunology and Microbiology
Domain: Life Sciences