Temporal trends, antimicrobial non-susceptibility patterns, and clinical predictors of Stenotrophomonas maltophilia in a tertiary care hospital in Palestine: a 7-year retrospective study.

BACKGROUND

Stenotrophomonas maltophilia is an opportunistic pathogen of increasing clinical importance because of its intrinsic resistance to multiple antimicrobial agents and its growing presence in healthcare environments. However, data describing its epidemiology and antimicrobial susceptibility patterns in Palestine remain limited. This study examined temporal trends, distribution across specimen types and care settings, and antimicrobial resistance profiles of S. maltophilia isolates.

METHODS

A retrospective observational study was conducted at a tertiary care hospital between 2018 and 2024. Unique clinical isolates of S. maltophilia were identified using the VITEK® 2 Compact system. Antimicrobial susceptibility to cotrimoxazole, levofloxacin, and ceftazidime was interpreted according to Clinical and Laboratory Standards Institute (CLSI) criteria applied during the respective testing period. Temporal changes in prevalence, distribution across hospital wards and specimen types, and antimicrobial non-susceptibility patterns were evaluated using stratified analyses, trend tests, and multivariable logistic regression models.

RESULTS

A total of 177 unique S. maltophilia isolates were identified, corresponding to a prevalence of 1.08% among all cultures performed. Annual prevalence fluctuated during the study period without evidence of a sustained linear trend. Respiratory specimens accounted for the largest proportion of isolates, and more than one-third originated from intensive care unit (ICU)-related settings. Susceptibility remained highest for cotrimoxazole (80.2%) and levofloxacin (78.5%), whereas ceftazidime showed lower historical non-susceptibility rates (42.9%). Paired analyses demonstrated significantly higher non-susceptibility to ceftazidime than to cotrimoxazole or levofloxacin (p < 0.001). Combined non-susceptibility (non-susceptibility to all three tested agents; CNP) occurred in 5.6% of isolates and was significantly more frequent among ICU-related isolates (21.7% vs. 3.2%, p = 0.004). In multivariable analyses, prior antibiotic exposure (p = 0.044) and COVID-19 infection (p = 0.027) were independently associated with levofloxacin non-susceptibility, whereas invasive medical device use was associated with ceftazidime non-susceptibility (p = 0.004).

CONCLUSIONS

S. maltophilia isolates demonstrated heterogeneous antimicrobial non-susceptibility patterns, with preserved susceptibility to cotrimoxazole and levofloxacin but reduced activity of ceftazidime. The higher frequency of the combined non-susceptibility phenotype (CNP) among ICU-related isolates suggests that critical care settings may serve as reservoirs for more resistant phenotypes. Continued microbiological surveillance and antimicrobial stewardship are essential to guide empiric therapy and infection-control strategies.

CLINICAL TRIAL REGISTRATION: Not applicable.