Stenotrophomonas Maltophilia Research Articles

Enhanced Suppression of Stenotrophomonas maltophilia by a Three-Phage Cocktail: Genomic Insights and Kinetic Profiling.

In our era of rising antibiotic resistance, Stenotrophomonas maltophilia (STM) is an understudied, gram-negative, aerobic bacterium widespread in the environment and increasingly causing opportunistic infections. Treating STM infections remains difficult, leading to an increase in disease severity and higher hospitalization rates in people with Cystic Fibrosis (pwCF), cancer, and other immunocompromised health conditions. The lack of effective antibiotics has led to renewed interest in phage therapy; however, there is a need for well-characterized phages. In response to an oncology patient with a respiratory infection, we collected 18 phages from Southern California wastewater influent that exhibit different plaque morphology against STM host strain B28B, cultivated from a blood sample. Here, we characterize the genomes and life cycle kinetics of our STM phage collection. We hypothesize that genetically distinct phages give rise to unique lytic life cycles that can enhance bacterial killing when combined into a phage cocktail compared to the individual phages alone. We identified three genetically distinct clusters of phages, and a representative from each group was screened for potential therapeutic use and investigated for infection kinetics. The results demonstrated that the three-phage cocktail significantly suppressed bacterial growth compared to individual phages when observed for 48 hours. We also assessed the lytic impacts of our three-phage cocktail against a collection of 46 STM strains to determine if a multi-phage cocktail can expand the host range of individual phages. Our phages remained strain-specific and infect >50% of tested strains. The multi-phage cocktail maintains bacterial growth suppression and prevents the emergence of phage-resistant strains throughout our 40-hour assay. These findings suggest specialized phage cocktails may be an effective avenue of treatment for recalcitrant STM infections resistant to current antibiotics.

In silico-driven identification and experimental confirmation of antifungal proteins (AFPs) against Candidaalbicans

Mycoses infect millions of people annually across the world. The most common mycosis agent, Candida albicans is responsible for a great deal of illness and death. C. albicans infection is becoming more widespread and the current antifungals polyenes, triazoles, and echinocandins are less efficient against it. Investigating antifungal peptides (AFPs) as therapeutic is gaining momentum. Therefore, we used MALDI-TOF/MS analysis to identify AFPs and protein-protein docking to analyze their interactions with the C. albicans target protein. Some microorganisms with strong antifungal action against C. albicans were selected for the isolation of AFPs. Using MALDI-TOF/MS, we identified 3 AFPs Chitin binding protein (ACW83017.1; Bacillus licheniformis), the bifunctional protein GlmU (BBQ13478.1; Stenotrophomonas maltophilia), and zinc metalloproteinase aureolysin (BBA25172.1; Staphylococcus aureus). These AFPs showed robust interactions with C. albicans target protein Sap5. We deciphered some important residues in identified APFs and highlighted interaction with Sap5 through hydrogen bonds, protein-protein interactions, and salt bridges using protein-protein docking and MD simulations. The three discovered AFPs-Sap5 complexes exhibit different levels of stability, as seen by the RMSD analysis and interaction patterns. Among protein-protein interactions, the remarkable stability of the BBQ25172.1-2QZX complex highlights the role of salt bridges and hydrogen bonds. Identified AFPs could be further studied for developing successful antifungal candidates and peptide-based new antifungal therapeutic strategies as fresh insights into addressing antifungal resistance also.

Antimicrobial susceptibility in bacterial isolates from water and agricultural products of the Chanchán river, Chimborazo Province, Ecuador

Introduction: river contamination with pathogenic and multidrug-resistant microorganisms is a public health issue due to its impact on health and its potential to transmit infectious diseases. Objective: To determine the presence of multidrug-resistant bacteria in irrigation water samples and agricultural products from the Chachán River. Method: a descriptive, non-experimental study with a quantitative and cross-sectional approach was conducted. Water samples were collected from six different points, and pH and temperature were measured. Additionally, 13 agricultural product samples from the same points were analyzed. The identification and antimicrobial susceptibility testing of bacteria were performed using the VITEK2 system and amplification and sequencing of the 16S rRNA gene. Results: a total of 17 bacterial strains were isolated from the water samples, 16 of which (94 %) belonged to the order Enterobacterales, including Proteus mirabilis, Proteus vulgaris, Morganella morganii, and Citrobacter diversus. From the agricultural products, 24 bacteria were isolated, including species of Klebsiella, Stenotrophomonas maltophilia, and Enterococcus faecalis. Antimicrobial resistance was observed in various strains, notably P. mirabilis, C. diversus, and P. vulgaris with multiple resistances. Resistance was also identified in pathogenic strains such as Yersinia enterocolitica, Plesiomonas shigelloides, and Aeromonas hydrophila. Conclusions: the Chachan River and the agricultural products irrigated with its waters contain multidrug-resistant bacteria, posing a significant risk to public health. It is crucial to implement control and monitoring measures to reduce the spread of these pathogens and ensure food safety

Infectious Diseases Society of America 2024 Guidance on the Treatment of Antimicrobial-Resistant Gram-Negative Infections.

The Infectious Diseases Society of America (IDSA) is committed to providing up-to-date guidance on the treatment of antimicrobial-resistant (AMR) infections. This guidance document focuses on infections caused by extended-spectrum β-lactamase-producing Enterobacterales (ESBL-E), AmpC β- lactamase-producing Enterobacterales (AmpC-E), carbapenem-resistant Enterobacterales (CRE), Pseudomonas aeruginosa with difficult-to-treat resistance (DTR P. aeruginosa), carbapenem-resistant Acinetobacter baumannii (CRAB), and Stenotrophomonas maltophilia. This updated document replaces previous versions of the guidance document. A panel of six infectious diseases specialists with expertise in managing antimicrobial- resistant infections formulated questions about the treatment of infections caused by ESBL-E, AmpC-E, CRE, DTR P. aeruginosa, CRAB, and S. maltophilia. Because of differences in the epidemiology of AMR and availability of specific anti-infectives internationally, this document focuses on the treatment of AMR infections in the United States. Preferred and alternative suggested treatment approaches are provided with accompanying rationales, assuming the causative organism has been identified and antibiotic susceptibility results are known. Approaches to empiric treatment, transitioning to oral therapy, duration of therapy, and other management considerations are discussed briefly. Suggested approaches apply for both adult and pediatric populations, although suggested antibiotic dosages are provided only for adults. The field of AMR is highly dynamic. Consultation with an infectious diseases specialist is recommended for the treatment of AMR infections. This document is current as of December 31, 2023 and will be updated periodically. The most current version of this document, including date of publication, is available at www.idsociety.org/practice-guideline/amr-guidance/.

Microbiological Landscape of Intensive Care Unit: A Retrospective Analysis of Bacterial Pathogens and Their Implications

Introduction: The intensive care unit (ICU) is a high-risk environment for hospital-acquired infections (HAIs) due to the complex interplay of patient vulnerability, invasive procedures, and the selective pressure of antimicrobial use. Understanding the local epidemiology of bacterial pathogens is crucial for effective infection prevention and control strategies. This study aimed to characterize the bacterial profile in an ICU setting, providing insights into the prevalent pathogens and their potential implications for patient care. Methods: A retrospective cross-sectional study was conducted, encompassing patients admitted to the ICU of Bangli Hospital Bali in 2023 and 2024. Data on patient demographics, sample sources, and microbiological findings were collected from medical records. Samples included blood cultures, sputum cultures (from both endotracheal tubes and spontaneous expectoration), wound swabs, and other sterile site cultures. Microbiological identification was performed using standard laboratory techniques. Results: A total of 219 patients were included in the study. The most common sample source was blood culture (42.9%), followed by sputum culture from endotracheal tubes (39.3%). A significant proportion of cultures showed no growth (34.7%), highlighting the challenges in identifying causative pathogens in the ICU. Among the identified pathogens, Staphylococcus spp. was predominant (15.5%), followed by Stenotrophomonas maltophilia (9.6%) and coagulase-negative staphylococci (8.7%). The distribution of pathogens varied across sample sources, with Staphylococcus spp. being prevalent in sputum cultures from endotracheal tubes and Klebsiella pneumoniae in sputum cultures. Conclusion: This study underscores the dynamic nature of the microbiological landscape in the ICU. The predominance of Staphylococcus spp., Stenotrophomonas maltophilia, and other opportunistic pathogens emphasizes the need for robust infection prevention and control measures. Further research is warranted to explore the impact of these pathogens on patient outcomes and to optimize antimicrobial stewardship in this critical care setting.

Case presentation of urinary tract infection by <i>StenotrophomonaS maltophilia</i>

Stenotrophomonas maltophilia is an emerging aerobic, non-fermentative, gram-negative multidrug-resistant global opportunistic bacillus. S. maltophilia causes a wide range of infections including respiratory tract infections, blood stream infections and, less commonly, biliary tract infections, skin and soft tissue infections, as well as bone and joint infections. It is increasingly being reported to cause urinary tract infections (UTIs). As for the case report, a 87-year-old male patient visited the Biopathology Laboratory of Nikea Primary Healthcare Center, Piraeus, Greece, for routine examination, being referred by the family doctor (GP). Patient history revealed diabetes mellitus type 2, arterial hypertension, hypercholesterolemia, hypertriglyceridemia, hyperuricemia, chronic obstructive pulmonary disease, diagnosed before 30 years prostate cancer Gleasongrade 6, operated before 15 years, followed by hormone therapy and radiation therapy. Patient history also revealed urinary tract stones with 3 episodes of obstructive pyelonephritis during the last 5 years, followed by hospital admissions and administration of intravenous antibiotic treatment. During the hospital admissions, he had a permanent bladder catheter and received special antimicrobial treatment, for various microorganisms detected in his urine samples, such as Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis and Enterococcus faecalis. Urinary incontinence has been a symptom for 15 years, after the prostate cancer surgery. Moreover, during the last 5 years, the patient faced many difficulties in his daily life because of the urinary incontinence. The situation was managed by bladder catheterisation, which further worsened his condition with recurrent UTIs and new episodes of pyelonephritis with subsequent hospitalization. Urinalysis showed proteinuria, intense pyuria, abundance of micro-organisms and abundance of red blood cells. The urine culture grew monomicrobial Stenotrophomonas maltophilia 105 CFU/ml. The bacterium was identified by the RapID™ REMEL ONE identification system (Thermo Fisher Scientific). Antimicrobial susceptibility testing revealed susceptibility to Trimethoprime/Sulfamethoxazole, Levofloxacin, Ceftriaxone and moderate susceptibility to Ciprofloxacin and Norfloxacin.The patient received treatment with Trimethoprime/Sulfamethoxazole.

A green zwitterionic bi-continuous membranes prepared by dual-bath procedure for mitigating biofouling during bacterial removal from water

This work explores the possibility of forming green microfiltration antifouling membranes based on polyvinylidene fluoride (PVDF) and a zwitterionic copolymer derivative of sulfobetaine methacrylate (SBMA), utilizing gamma-valerolactone (GVL) as the solvent and a mixture of ethanol and water as non-solvents. Efforts were initially focused on adjusting the immersion time of the matrix polymer in alcohol alone to obtain a porous structure, and 15 s were sufficient to achieve a symmetric, open porous morphology. Next, the polymer/copolymer/solvent blend was characterized. While it did not show the characteristics of a fully miscible system, DLS and visual observations revealed the obtaining of a homogeneous (relatively narrow particle size) and transparent to translucent system. Thus, membranes could be cast, and were shown to be stable. The addition of the copolymer maintained the physical characteristics of microfiltration membranes, but an FT-IR analysis revealed its effect on the dominant crystalline polymorph (switching from β to α). The membrane wettability was enhanced in an important extent with a dynamic water contact angle (WCA) gradually falling to < 40° (while the virgin membrane's WCA remained about 138° all test long), and a hydration capacity reaching about 530 mg/cm3 against <10 mg/cm3 for the virgin membrane. It reflected on the antifouling abilities of the membranes as tested using bovine serum albumin, fibrinogen, Escherichia coli, and Stenotrophomonas maltophilia, with relative decreases in adsorption during static tests measured to be 95 %, 70 %, 91 % and 98 %, respectively. Finally, compared to the virgin membrane, the modified membrane featured improved flux recovery (32 % vs. 11 %), significantly higher rejection (98.9 % vs. 89.1 %) and lower irreversible fouling tendency (68 % vs. 89 %) during cyclic water/bacterial solution filtration in dead-end mode, making it potentially suitable for addressing bacterial pollution in wastewater.

Impact of Empirical Antimicrobial Treatment on Patients with Ventilator-Associated Pneumonia Due to Stenotrophomonas maltophilia.

This retrospective study was conducted to evaluate the characteristics and outcomes of patients with ventilator-associated pneumonia (VAP) caused by Stenotrophomonas maltophilia (S. maltophilia), focusing on the impact of appropriate empirical antimicrobial treatment. Of the enrolled 240 patients with VAP due to S. maltophilia (median age: 45 years) in a tertiary-care hospital in southern Thailand between January 2010 and December 2021, 90% had medical comorbidities and 91% had previously received carbapenems. In addition, only 45% of the patients were initially admitted to the intensive care unit. Patients administered appropriate empirical antimicrobial treatment including colistin alone and colistin plus TMP-SMX or fluoroquinolone-based regimens had significantly lower 14-day, 30-day, and in-hospital mortalities, compared with those who did not receive appropriate empirical antimicrobial treatment (21% and 2% vs. 31%; 30% and 5% vs. 44%; and 30% and 12% vs. 53%, respectively). Thus, the use of appropriate empirical antimicrobial treatments led to a significantly reduced length of hospital stay, duration of ventilation, and hospital costs. The current study suggests that the use of appropriate empirical antimicrobial treatment based on susceptibility testing without considering pharmacokinetic properties and administration dosages improves the outcomes of patients with VAP due to S. maltophilia.

Stenotrophomonas maltophilia G17: Potential antifungal agent isolated from the gut of black soldier fly larvae against Ganoderma boninense

Oil palm (Elaeis guineensis Jacq.) is the primary source of foreign exchange in Indonesia's plantation sector. However, these plants are very vulnerable to attack by Ganoderma spp., which causes basal stem rot (BSR) and upper stem rot (USR) disease, resulting in significant economic losses. In this study, antagonistic assays of the G17 isolate obtained from the gut of black soldier fly (BSF) larvae showed potential biocontrol against G. boninense. Furthermore, antibiosis assays showed that the Stenotrophomonas maltophilia G17 isolate inhibited the growth of G. boninense by up to 85.56%–91.98%. Molecular identification using 16S rRNA, reinforced by biochemical characterization tests, confirmed the G17 isolate as S. maltophilia. Growth test results showed that S. maltophilia G17 cannot grow at a temperature of 37 °C within 24 h. The isolate also exhibited negative hemolytic activity, indicating it is not a pathogenic bacterium. S. maltophilia G17 exhibited lytic enzymes such as proteolytic, lipolytic, and chitinolytic activity. Among them, chitinolytic enzymes might be involved in the biocontrol process.

Prevalence of Co-infection of Culture-Proven Bacterial Pathogens in Microbiologically Confirmed Pulmonary Tuberculosis Patients From a Tertiary Care Center.

Tuberculosis (TB) is a chronic condition that weakens the immune system, causes structural changes in the lungs, and can lead to infections by other bacterial pathogens. Very few studies have been done to understand the magnitude of co-infection with other bacterial pathogens, so this study was conducted to understand the co-infection pattern and burden. A total of 174 microbiologically confirmed pulmonary TB patients' samples, identified by cartridge-based nucleic acid amplification test, were further tested for other bacterial pathogens by culture over a period of five months from May 2023 to September 2023. The isolates' identification and drug susceptibility were performed using the VITEK 2 system (bioMérieux, Marcy-l'Étoile, France). Of the 174 pulmonary samples tested, 19 samples grew a significant amount of other bacterial pathogens, making the prevalence 10.91% (19/174). Among the pulmonary samples tested, 54.59% were sputum, 38.5% were bronchoalveolar lavage, and 6.89% were endotracheal aspirate. Additionally, 70.11% of the patients tested were in the age group of 19-60 years. Of the patients who had co-infection, 94.73% (18/19) were male. The most common bacterial infection was caused by Pseudomonas aeruginosa, which was identified in 36.84% of the co-infection cases (7/19). This was followed by Acinetobacter baumannii in 31.57% (6/19), Klebsiella pneumoniae in 26.31% (5/19), and Stenotrophomonas maltophilia in 5.28% (1/19). Acinetobacter baumannii and Klebsiella pneumoniae showed high drug resistance, ranging from 60% to 100% against various groups of drugs tested. None of the patient samples with co-infection showed rifampicin resistance. Among all the samples with co-infection, the majority (42.10%, or 8/19) had a high load of Mycobacterium tuberculosis complex detected by CBNAAT Ultra (Cepheid, Sunnyvale, California). Pseudomonas aeruginosa, Acinetobacter baumannii, and Klebsiella pneumoniae are unusual pathogens causing infection in community patients and are known to cause illness in hospitalized patients. These organisms' resistance was also similar to the resistance shown by hospital-acquired infections. Thisindicates that bacterial co-infection in pulmonary TB patients will be similar to the pattern of hospital-acquired infections. The high prevalence of bacterial co-infections (10.91%) in patients with pulmonary TB poses a significant challenge as these bacterial pathogens are not susceptible to anti-tubercular drugs. Therefore, comprehensive screening for other bacterial infections in all pulmonary TB patients is crucial for effective treatment and outcomes.

Assessment of carbapenem resistance and carbapenemase genes in wastewater from cattle slaughterhouses: Implications for environmental antibiotic resistance surveillance

The objectives of the study were to determine the prevalence of carbapenem-resistant Gram-negative bacteria and assess the potential risks associated with cattle slaughterhouse wastewater. A total of 270 wastewater samples were collected from 10 different cattle slaughterhouses for microbiological analysis. Conventional culture methods were employed, followed by disc diffusion, the Modified Carbapenem Inactivation Method (mCIM), and the Modified Hodge Test (MHT) to identify carbapenem resistance. The Vitek® 2 compact system was used for species identification and antibiotic susceptibility profiling. Conventional and quantitative PCR (qPCR) were performed to detect specific carbapenemase genes (blaKPC, blaNDM, and blaOXA-48). Among the collected 72 carbapenem-resistant isolates, one Pseudomonas fluorescens, one Aeromonas hydrophila, and two Aeromonas sobria exhibited resistance to meropenem. Additionally, six P. fluorescens and two A. hydrophila isolates demonstrated intermediate resistance to meropenem. Furthermore, five carbapenem-resistant isolates were identified as Stenotrophomonas maltophilia, known to be inherently resistant to most antibiotics. Ten different antibiotics were evaluated in the antibiotic resistance panel and all Aeromonas isolates were found to be resistant to cefazolin and one A. hydrophila was detected as multi-drug resistant. The revealed data indicates that slaughterhouse wastewater can serve as a reservoir for antibiotic-resistant opportunistic pathogens. However, it may not pose a substantial risk for the distribution of carbapenemases, thereby mitigating concerns related to potential public health and environmental hazards associated with this aspect of slaughterhouse operations. This study contributes to understanding of antibiotic resistance in livestock-related environments and underscores the importance of continued monitoring and surveillance.

Analysis of blood microbiota in patients with adult-onset Still's disease and sepsis by metagenomic next-generation sequencing.

Aims/Background Adult-onset Still's disease (AOSD) shares similar clinical symptoms with sepsis. Thus, differentiating between AOSD and sepsis presents a great challenge while making diagnosis. This study aimed to analyse the changes in blood microbiota related to AOSD and sepsis using metagenomic next-generation sequencing (mNGS), identify potential biomarkers that distinguish AOSD from sepsis, and explore the diagnostic value of mNGS in differentiation between these two pathological conditions. Methods Clinical data of four AOSD patients and four sepsis patients treated in the Department of Rheumatology and Immunology, The Affiliated Hospital of Xuzhou Medical University between October 2021 and February 2022 were collected. The mNGS diagnostic records of these patients were analysed for microbial correlations in terms of species taxonomic structure and beta diversity by comparing blood microbiota between AOSD and sepsis. The biomarkers with the strongest capability in distinguishing the subgroups were screened using a random forest algorithm. Results There was no statistically significant differences between AOSD patients and sepsis controls in terms of gender and age (p > 0.05). A total of 91 operational taxonomic units (OTUs) were obtained. At the level of phylum, Proteobacteria, Ascomycota and Basidiomycota were present in high abundances in both groups (79.76%, 14.18% and 3.30% vs 54.03%, 32.77% and 5.81%). At the genus level, the abundances of Parainfluenzae, Aspergillus and Ralstonia were the top three highest in the AOSD group (73.88%, 10.92% and 5.48%), while Ralstonia, Aspergillus and Malassezia were ranked as the top three in the sepsis group in term of abundance (48.69%, 27.36% and 5.52%). In beta-diversity analysis, there were advances shown in visual principal coordinates analysis (PCoA) and non-metric multidimensional scaling (NMDS) between the AOSD group and sepsis group (p < 0.05), with little significant differences in the analysis of similarities (Anosim) (p > 0.05). Linear discriminant analysis effect size (LEfSe) showed that Mucoromycota, Saccharomycetes, Moraxellales, Mucorales, Xanthomonadales, Saccharomycetales, Acinetobacter, Stenotrophomonas, Yarrowia, Apophysomyces, Acinetobacter johnson, Yarrowia lipolytica, Apophysomyces variabilis and Stenotrophomonas maltophilia were more enriched in sepsis group (p < 0.05). The top five variables with the strongest capability in distinguishing between AOSD and sepsis were Acinetobacter johnsonii, Apophysomyces variabilis, Propionibacterium acnes, Stenotrophomonas maltophilia and Yarrowia lipolytica. Conclusion The blood microorganisms in AOSD were different from sepsis, and mNGS was potential to distinguish between AOSD and sepsis.

Effective strategies for managing trimethoprim-sulfamethoxazole and levofloxacin-resistant Stenotrophomonas maltophilia infections: bridging the gap between scientific evidence and clinical practice.

To discuss the therapeutic options available for the management of difficult-to-treat strains of Stenotrophomonas maltophilia (Sma), namely those resistant to trimethoprim-sulfamethoxazole and fluoroquinolones. Recent pharmacological studies have highlighted the fact that current breakpoints for first-line antibiotics against Sma are too high. In light of these data, it is likely that the prevalence of difficult-to-treat (DTR) Sma is underestimated worldwide. Two promising alternatives for treating DTR strains are cefiderocol and the combination of aztreonam and an L2 inhibitor. However, clinical trials are currently very limited for these antibiotics and no comparative studies have been carried out to date. It is important to note that the clinical efficacy of cefiderocol appears to be inferior to that initially anticipated from in-vitro and animal studies. Consequently, minocycline and ceftazidime may remain viable options if they are used against strains with a low minimum inhibitory concentration. We advise against the use of intravenous polymyxins and tigecycline. Finally, recent literature does not support the systematic use of combination therapy or long-course treatments. In the coming years, phage therapy may become a promising approach against DTR Sma infections. Overall, clinical comparative studies focused on DTR strains are required in order to provide more accurate and actionable information for therapeutic decisions.

Evaluation of BACTEC™ FX and BacT/Alert™ Automated Blood Culture Systems for Detection of Clinically Relevant Bacterial and Yeast Species

Background: Bloodstream infections (BSI) are a significant health concern, necessitating effective diagnostic tools. This study evaluates the performance of the BD Bactec FX system in comparison to the established BacT/Alert system, examining mean time till detection (TTD) across various blood culture bottles.Methods: The study involves 148 blood culture bottles, inoculated with representative bacterial ATCC strains (n= 15) and 04 yeast isolates. Parallel testing is conducted by seeding 10–30 colony-forming units (CFU) in duplicate in both BD Bactec FX and BacT/Alert systems. TTD is assessed across aerobic, anaerobic, and pediatric bottles for diverse microbial species.Results: All 148 bottles tested in parallel show positive signals in both systems. BD Bactec FX demonstrates significantly shorter TTD for adult-seeded cultures in aerobic and anaerobic bottles compared to BacT/Alert Similarly, pediatric bottles with BD Bactec FX exhibit a shorter TTD compared to BacT/Alert. The statistical significance of TTD, 95% confidence intervals (CI), and p-values is evident for Bactec FX aerobic, anaerobic, and pediatric bottles across tested organisms. Notable examples of faster TTD include; Bacteroides ovatus (16.6h by Bactec FX vs. 70.5h by Bact/Alert 3D), Stenotrophomonas maltophilia (33.7h vs. 72.5h), and Streptococcus pyogenes (8.1h vs. 11.9h).Conclusions: In conclusion, the study’s findings demonstrate that BD Bactec FX surpasses BacT/Alert in prompt microbial detection, showcasing potential for early identification of bacteremia and fungemia. Faster TTD implies the potential to initiate timely antimicrobial treatment, thereby reducing patient morbidity and mortality. However, exceptions in certain microbial species highlight the need for comprehensive clinical validation to establish the broad applicability of these findings.Keywords: Blood Culture System; Recovery Rate; Time to detection; Blood stream infection; BTA3D; Bactec FX

Determination of in vitro synergy and antibiofilm activities of antimicrobials and essential oil components

Using existing adrentimicrobials with essential oil components to prevent antimicrobial resistance is an alternative strategy. This study aimed to evaluate the resistance status, synergistic combinations, and in vitro biofilm formation activities of clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA), Stenotrophomonas maltophilia and Candida albicans against antimicrobial agents and cinnamaldehyde, carvacrol, eugenol, limonene and eucalyptol. Antimicrobial activities were evaluated by microdilution, cytotoxicity by XTT, synergy by checkerboard and time-kill, and biofilm inhibition by microplate methods. Cinnamaldehyde and carvacrol showed strong antimicrobial activity. Synergistic effects were observed when using all essential oils with antimicrobials. Only two C. albicans isolates showed antagonism with cinnamaldehyde and fluconazole. The constituents showed cytotoxic effects in the L929 cell line (except limonene). A time-kill analysis revealed a bacteriostatic effect on S. maltophilia and MRSA isolates and a fungicidal effect on C. albicans isolates. These results are important for further research to improve antimicrobial efficacy or to develop new agents.

Clinical and microbiological features of positive blood culture episodes caused by non-fermenting gram-negative bacilli other than Pseudomonas and Acinetobacter species (2020-2023).

Non-fermenting Gram-negative bacilli (NFGNB) other than Pseudomonas aeruginosa and Acinetobacter baumannii complex are pathogens of interest due to their ability to cause health-care associated infections and display complex drug resistance phenotypes. However, their clinical and microbiological landscape is still poorly characterized. Observational retrospective study including all hospitalized patients presenting with a positive positive blood culture (BC) episode caused by less common NFGNB over a four-year period (January 2020-December 2023). Clinical-microbiological features and factors associated with mortality were investigated. Sixty-six less common NFGNB isolates other than Pseudomonas and Acinetobacter species causing 63 positive BC episodes were recovered from 60 patients. Positive BC episodes were predominantly sustained by Stenotrophomonas maltophilia (49.2%) followed by Achromobacter species (15.9%) that exhibited the most complex resistance phenotype. Positive BC episodes had bloodstream infection criteria in 95.2% of cases (60 out 63), being intravascular device (30.2%) and respiratory tract (19.1%) the main sources of infection. Fourteen-day, 30-day, and in-hospital mortality rates were 6.4%, 9.5%, and 15.9%, respectively. The longer time from admission to the positive BC episode, older age, diabetes, admission due to sepsis, and higher Charlson Comorbidity Index were identified as the main predictors of in-hospital mortality. Positive BC episodes sustained by NFGNB other than Pseudomonas and Acinetobacter species were predominantly sustained by Stenotrophomonas maltophilia and Achromobacter species, having bloodstream infection criteria in the vast majority of cases. Factors that have emerged to be associated with mortality highlighted how these species may have more room in prolonged hospitalisation and at the end of life for patients with chronic organ diseases.

A Case of Persistent Intra-Abdominal Stenotrophomonas maltophilia Infection Despite Bacteriophage Therapy.

Multidrug resistant infections are a challenge in the health care setting and a cause of patient morbidity and mortality. Bacteriophages (phages) are viruses that target and kill bacteria and have been used in patients to treat bacterial infections. We present a case of disseminated Stenotrophomonas maltophilia infection, with pulmonary, intra-abdominal and bloodstream involvement. The patient was treated with a combination of antibiotics and personalized phage therapy, administered daily for 12 days both intravenously as well as via intra-abdominal drains. Phage therapy was well-tolerated, the patient cleared S. maltophilia from their bloodstream and their intra-abdominal abscesses were stable or decreased in size. However, the intra-abdominal fluid cultures remained positive for S. maltophilia. Unfortunately, the patient passed away 2 months after completion of phage therapy due to multiorgan failure. These data highlight the difficulty of treating critically ill patients and clearing complex, biofilm mediated infections, even with phages. More information is needed regarding the optimal treatment protocols for phage therapy in complex multifocal infections.

Unlocking the potential of zwitterionic vapor-induced phase separation membranes synthesized from maleic anhydride in polyvinylidene fluoride-based systems for antifouling applications

This work presents an approach to form zwitterionic porous poly(vinylidene fluoride) (PVDF) membranes fabricated by vapor-induced phase separation (VIPS). The reaction between maleic anhydride groups, incorporated initially in the casting solution by blending styrene maleic anhydride (SMA), with 3-((3-aminopropyl)dimethylammonio)propane-1-sulfonate led to the desired zwitterionic moieties. XPS and FTIR analyses confirm the functionalization of the membrane. SEM analyses revealed that it did not have any major impact on the membrane morphology deemed to be close to bicontinuous. While the mean pore size of the virgin membrane was 0.57 μm, it increased to 0.85 μm suggesting the pore-forming effect of SMA during the phase-inversion process. Hydration was significantly enhanced, attributed to the zwitterionic groups on the one hand, but also to the formation of carboxylic acid and amide groups following the ring-opening reaction. It led to significant resistance to bacterial attachment as tested with 4 strains of bacteria including Escherichia coli, Stenotrophomonas maltophilia, Staphylococcus aureus and Streptococcus mutans (>99 % reduction for each). Applied in cyclic water/bacterial solution filtration tests, the modified membrane showed clear improvement in overall performances. Hence, for the virgin membrane, the initial water permeability, flux recovery ratio after the first cycle and flux recovery ratio after the second cycle were found to be 3000 L m−2 h−1.bar−1, 12 % and 53 %, respectively. For the optimized zwitterionic membrane, they were measured to be 7000 L m−2 h−1.bar−1, 26 % and 100 %, respectively. The efficacy of styrene maleic anhydride as a precursor for achieving stable and efficient zwitterionization of PVDF microfiltration membranes is evidenced, rendering it valuable for the filtration of microorganism-containing wastewater. Moreover, its potential application extends to the biomedical realm.

Temporal changes in the morphological and microbial diversity of biofilms on the surface of a submerged stone in the Danube River

Epilithic biofilms are ubiquitous in large river environments and are crucial for biogeochemical processes, but their community structures and functions remain poorly understood. In this paper, the seasonal succession in the morphological structure and the taxonomic composition of an epilithic bacterial biofilm community at a polluted site of the Danube River were followed using electron microscopy, high-throughput 16S rRNA gene amplicon sequencing and multiplex/taxon-specific PCRs. The biofilm samples were collected from the same submerged stone and carried out bimonthly in the littoral zone of the Danube River, downstream of a large urban area. Scanning electron microscopy showed that the biofilm was composed of diatoms and a variety of bacteria with different morphologies. Based on amplicon sequencing, the bacterial communities were dominated by the phyla Pseudomonadota and Bacteroidota, while the most abundant archaea belonged to the phyla Nitrososphaerota and Nanoarchaeota. The changing environmental factors had an effect on the composition of the epilithic microbial community. Critical levels of faecal pollution in the water were associated with increased relative abundance of Sphaerotilus, a typical indicator of “sewage fungus”, but the composition and diversity of the epilithic biofilms were also influenced by several other environmental factors such as temperature, water discharge and total suspended solids (TSS). The specific PCRs showed opportunistic pathogenic bacteria (e.g. Pseudomonas spp., Legionella spp., P. aeruginosa, L. pneumophila, Stenotrophomonas maltophilia) in some biofilm samples, but extended spectrum β-lactamase (ESBL) genes and macrolide resistance genes could not be detected.

A case of recurrent peritoneal dialysis-related peritonitis caused by Stenotrophomonas maltophilia during ongoing antibiotic treatment for Enterococcus faecalis-induced peritonitis.

Recurrent peritonitis is a serious complication of peritoneal dialysis (PD), which could result in PD withdrawal and mortality. However, cases of recurrent peritonitis occurring during ongoing antimicrobial therapy are rarely reported. Herein, we present a 71-year-old man who experienced initial peritonitis due to Enterococcus faecalis. Despite effective antimicrobial therapy, he developed recurrent peritonitis while on antimicrobial therapy. PD fluid culture analysis yielded Stenotrophomonas maltophilia (S. maltophilia). He was treated with multiple antimicrobials, and the peritoneal catheter was removed. To the best of our knowledge, this is the first case of recurrent peritonitis caused by S. maltophilia, which was developed during antimicrobial treatment. Our report findings suggest the importance of considering S. maltophilia infection in an atypical case of very early recurrent peritonitis.