Stenotrophomonas maltophilia: an emerging multidrug-resistant opportunistic pathogen in the immunocompromised host

Characterization and genomic analysis of phage vB_SmaP_c9-N, a novel Stenotrophomonas maltophilia podophage with antibiofilm activity

Stenotrophomonas maltophilia strains are increasingly emerging as multidrug-resistant pathogens. Moreover, S. maltophilia commonly produces biofilms that enhance antibiotic resistance in bacteria. Phages are effective alternative drugs for treating S. maltophilia infections. In this study, the lytic phage vB_SmaP_c9-N (abbreviated as Φc9-N), which is specific for S. maltophilia, was isolated from Nanhu Lake, Wuhan, China. Electron microscopy observation revealed that Φc9-N is a podophage. Φc9-N is stable over a wide pH range, from pH 4 to 10, and its activity did not change after storage at 4 °C for 2 months. The latency period of Φc9-N is 5 min, and its outbreak period is 35 min. Antibacterial tests showed that Φc9-N could effectively inhibit the growth of S. maltophilia c24. Moreover, the biofilm production of S. maltophilia c24 decreased when Φc9-N was administered either to the forming biofilm or to the mature biofilm. These results suggest that Φc9-N has application potential in clinical treatment. The genome of Φc9-N is a dsDNA of 43,170 bp with 55 putative unidirectional genes, 18 of which were assigned putative functions, while other genes encoded hypothetical proteins. Genome sequence comparisons and phylogenetic analysis indicated that Φc9-N represents a new species, and, together with the Stenotrophomonas phages BUCT700, BUCT703, BUCT598, and vB_SmaS_P15, can be included in the newly proposed genus "Maltovirus" in the family Autographiviridae.

Stenotrophomonas maltophilia, a Pathogen of Increasing Relevance to Dermatologists: A Case Report and Review of the Literature

Stenotrophomonas maltophilia is a Gram-negative bacillus that causes skin and soft tissue infections (SSTI), as well as bacteremia, pneumonia, and urinary tract infections. S. maltophilia infections are typically nosocomial and are often transmitted through water sources. Although historically described in immunocompromised hosts, S. maltophilia prevalence is increasing in both immunocompromised and immunocompetent populations. In light of high morbidity and mortality, it is critical that dermatologists are aware of this organism because of the limited options for therapy. Here, we describe a case of a S. maltophilia abscess with bacteremia in a patient with chronic lymphocytic leukemia and aplastic anemia that was successfully treated with trimethoprim-sulfamethoxazole. We also review the current standard of care and propose an algorithm for the treatment of S. maltophilia infection.

Isolation and characterization of the novel bacteriophage vB_SmaS_BUCT626 against Stenotrophomonas maltophilia

Stenotrophomonas maltophilia has been recognized as an emerging global opportunistic pathogen, and it is intrinsically resistant to most antibiotics, which makes the limited choice for treating S. maltophilia infections. Bacteriophage with the proper characterization is considered as a promising alternative treatment option to control S. maltophilia infections. In this study, we isolated a novel Siphoviridae bacteriophage vB_SmaS_BUCT626 with lytic activity against S. maltophilia. Phage vB_SmaS_BUCT626 can lysis 10 of 20 S. maltophilia and was relatively stable at a wide range of temperatures (4-70 °C) and pH values (3.0-13.0) and exhibited good tolerance to chloroform. The genome of phage vB_SmaS_BUCT626 was a 61,662-bp linear double-stranded DNA molecule with a GC content of 56.2%, and contained 100 open-reading frames. It carried no antibiotic resistance, toxin, virulence-related genes, or lysogen-formation gene clusters. Together, these characteristics make phage vB_SmaS_BUCT626, a viable candidate as a biocontrol agent against S. maltophilia infection.

Fatal hemorrhagic pneumonia in patients with hematologic diseases and Stenotrophomonas maltophilia bacteremia: a retrospective study

Background

Fatal hemorrhagic pneumonia is one of the most severe manifestations of Stenotrophomonas maltophilia (SM) infections. Here, we aimed to investigate the clinical characteristics of SM bacteremia and to identify the risk factors of hemorrhagic pneumonia caused by SM in patients with hematologic diseases.

Methods

The clinical records of 55 patients diagnosed with hematologic diseases and SM bacteremia were retrospectively reviewed. We compared patients’ clinical characteristics and outcomes between the hemorrhagic pneumonia group and non-hemorrhagic pneumonia group.

Results

Twenty-seven (49.1%) patients developed hemorrhagic pneumonia. The overall mortality rate of SM bacteremia was 67.3%. Hemorrhagic pneumonia (adjusted HR 2.316, 95% CI 1.140–4.705; P = 0.020) was an independent risk factor of 30-day mortality in hematological patients with SM bacteremia. Compared with the non-hemorrhagic pneumonia group, patients in the hemorrhagic pneumonia group were older and showed clinical manifestations as higher proportions of isolated SM in sputum culture, neutropenia and elevated procalcitonin (PCT). Multivariate analysis showed that neutropenia, high levels of PCT, prior tigecycline therapy within 1 month were independent risk factors associated with hemorrhagic pneumonia.

Conclusions

Neutropenia, high level of PCT and prior tigecycline therapy within 1 month were significant independent predictors of hemorrhagic pneumonia in hematologic patients with SM bacteremia. Due to no effective antibiotics to prevent hemorrhagic pneumonia, prophylaxis of SM infection and its progression to hemorrhagic pneumonia is particularly important.

Advances in the Microbiology of Stenotrophomonas maltophilia

Stenotrophomonas maltophilia is an opportunistic pathogen of significant concern to susceptible patient populations. This pathogen can cause nosocomial and community-acquired respiratory and bloodstream infections and various other infections in humans. Sources include water, plant rhizospheres, animals, and foods. Studies of the genetic heterogeneity of S. maltophilia strains have identified several new genogroups and suggested adaptation of this pathogen to its habitats. The mechanisms used by S. maltophilia during pathogenesis continue to be uncovered and explored. S. maltophilia virulence factors include use of motility, biofilm formation, iron acquisition mechanisms, outer membrane components, protein secretion systems, extracellular enzymes, and antimicrobial resistance mechanisms. S. maltophilia is intrinsically drug resistant to an array of different antibiotics and uses a broad arsenal to protect itself against antimicrobials. Surveillance studies have recorded increases in drug resistance for S. maltophilia, prompting new strategies to be developed against this opportunist. The interactions of this environmental bacterium with other microorganisms are being elucidated. S. maltophilia and its products have applications in biotechnology, including agriculture, biocontrol, and bioremediation.

Oral Microbiome Profiling in Smokers with and without Head and Neck Cancer Reveals Variations Between Health and Disease

While smoking is inextricably linked to oral/head and neck cancer (HNSCC), only a small fraction of smokers develop HNSCC. Thus, we have sought to identify other factors, which may influence the development of HNSCC in smokers including microbiology. To determine microbial associations with HNSCC among tobacco users, we characterized oral microbiome composition in smokers with and without HNSCC. 16S rRNA MiSeq sequencing was used to examine the oral mucosa microbiome of 27 smokers with (cases) and 24 without HNSCC (controls). In addition, we correlated previously reported levels of DNA damage with the microbiome data. Smokers with HNSCC showed lower microbiome richness compared with controls (q = 0.012). Beta-diversity analyses, assessed as UniFrac (weighted and unweighted) and Bray-Curtis distances, showed significant differences in oral mucosal microbiome signatures between cases and controls (r ² = 0.03; P = 0.03) and higher interindividual microbiome heterogeneity in the former (q ≤ 0.01). Higher relative abundance of Stenotrophomonas and Comamonadaceae and predicted bacterial pathways mainly involved in xenobiotic and amine degradation were found in cases compared with controls. The latter, in contrast, exhibited higher abundance of common oral commensals and predicted sugar degradation pathways. Finally, levels of DNA damage in the oral cavity were correlated with the microbiome profiles above. Oral microbiome traits differ in smokers with and without HNSCC, potentially informing the risk of eventual HNSCC and shedding light into possible microbially mediated mechanisms of disease. These findings present data that may be useful in screening efforts for HNSCC among smokers who are unable to quit.