Epidemiological Trends and Resistance Associated with Stenotrophomonas maltophilia Bacteremia: A 10-Year Retrospective Cohort Study in a Tertiary-Care Hospital in Hungary

Abstract

Stenotrophomonas maltophilia has been recognized as an emerging nosocomial pathogen in invasive infections of immunocompromised, severely debilitated patients with significant underlying illnesses. The first-choice drug in these infections is sulfamethoxazole-trimethoprim (SMX/TMP), and resistance to this antimicrobial is a daunting challenge for clinicians. The aim of this study was to assess the prevalence of S. maltophilia bacteremia and SMX/TMP-resistance levels at a tertiary-care university hospital. A total of 175 episodes of S. maltophilia bacteremia were identified (2008–2012: n = 82, 2013–2017: n = 93; p = 0.061), 52% of affected patients were 60 years of age, and had recent surgery, severe injuries or underlying conditions (malignant hematologic diseases and solid tumors) in their history. Sixteen percent of isolates were resistant to SMX/TMP (2008–2012: n = 13.8%, 2013–2017: n = 17.2%; p = 0.076), and out of the resistant strains, 32.7% were also resistant to levofloxacin and colistin. Our findings on the SMX/TMP-resistance were similar to global literature data.

A 10-year single-center experience on Stenotrophomonas maltophilia resistotyping in Szeged, Hungary

“…Empiric therapy of S. maltophilia infections is sulfamethoxazole/trimethoprim, combined with levofloxacin or ticarcillin/clavulanate (if available); the therapeutic protocol should be revised after the susceptibility results are available [1,2,12,14]. Resistance rates to sulfamethoxazole/trimethoprim (12.6%) was higher than the range of resistance in Western European countries (2-10%), although outlier countries with higher resistance (e.g., Spain: 25-27%, Turkey: 10-15%) have already been noted [36,37].…”

“…The relevance of the other three tested agents in clinical situations is harder to ascertain, as there are no evidence or clinical trials correlating their efficacy in the therapy of S. maltophilia infections [38]. In addition (as demonstrated in the Methods section), there are also contradictory information regarding susceptibility-testing method for these bacteria: based on EUCAST, disk diffusion is only available for sulfamethoxazole/trimethoprim, while CLSI offers disk diffusion testing breakpoints for levofloxacin and minocycline as well [12,14,39]. Some drugs, not even MIC breakpoints are available (thus, clinical microbiologists should not interpret them as susceptible or resistant for the treating physicians), as the pharmacokinetic/pharmacodynamic attributes, outcomes and antimicrobial efficacy of these antibiotics have not been characterized in relation with S. maltophilia infections [12,14,39].…”

“…The study included S. maltophilia bacterial isolates from blood culture samples, respiratory samples and urine samples and the data for the samples from all outpatient Clinics and impatient departments, corresponding to the time period between January 2008 until December 2017. Bacterial isolates were considered separate if they were detected more than 14 days apart, or S. maltophilia isolates with different antibiotic susceptibilities were isolated [12]. Isolates collected for surveillance/infection control purposes from hospital environments were excluded from the analysis.…”

Taxonomy and nomenclature of bacteria with clinical and scientific importance: current concepts for pharmacists and pharmaceutical scientists

“…for Roseococcus) to ease correspondences regarding anoxygenic phototrophic bacteria, other "real word" examples include mosaic terms derived from names of bacterial groups (e.g., GAS: Group A Streptococcus; ESKAPE: Enterococcus faecium, S. aureus, Klebsiella spp., Acinetobacter baumannii, P. aeruginosa, Enterobacter spp. ), therapeutic recommendations (e.g., MRSA: methicillin-resistant S. aureus) or public health significance (e.g., MSTM: multidrug-resistant Stenotrophomonas maltophilia, MDRAB: multidrug-resistant A. baumannii) [27,[38][39][40][41][42][43]. It must be noted that in medicine (especially as far as the clinical microbiologist-physician relationship is concerned), the use of commonly known names is preferred, which are not subject to change (irrespective of taxonomic changes), so that the doctors reading the reports, e.g., of a susceptibility test can comprehend them [29][30][31][32][33][34][35][36].…”

“…Due to the rapid developments in bacterial taxonomy, both consisting of the description of novel taxa and reclassification of existing bacterial genera to other taxonomical units (e.g., the history of S. maltophilia: it first described as Bacterium booker (1943), later on, it was redesignated as Pseudomonas maltophilia (1958) and Xanthomonas maltophilia (1981); finally, in 1993, the genus Stenotrophomonas was proposed), it is very difficult, if not impossible for researchers, officials, public health microbiologists and healthcare professionals to keep in mind all the accepted or proposed changes [26,27]. However, the importance of correct taxonomy in scientific communication and the diagnostics and therapy of bacterial infections cannot be underestimated [3].…”