Cefiderocol susceptibility of 146 Stenotrophomonas maltophilia strains clinically isolated from blood in two Japanese hospitals over a 10-year period.

Previous reports focusing on cefiderocol susceptibility against Stenotrophomonas maltophilia have included a large number of noninvasive or colonized isolates, and data focusing on invasive S. maltophilia strains are still lacking. We retrospectively investigated the cefiderocol susceptibility of stored S. maltophilia strains that caused bacteremia at two Japanese hospitals. The MIC50 and MIC90 were 0.06 µg/mL and 0.25 µg/mL, respectively, while the susceptibility rate was 99.3% (current CLSI breakpoint criteria). Our results provide the MIC distribution of bacteremic S. maltophilia isolates in Japan and show the preserved cefiderocol susceptibility of S. maltophilia among clinically invasive pathogenic strains.

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.

Successful therapy of a newborn with Stenotrophomonas maltophilia nosocomial pneumonia with cefiderocol.

Cefiderocol is a new siderophore-beta-lactam antibiotic used for the treatment of severe multidrug-resistant infections like sepsis, hospital-acquired and ventilator-associated pneumonia in adults, but there are only single reports on its use in the neonatal population. We describe the successful cefiderocol treatment of a newborn with pneumogenic sepsis due to Stenotrophomonas maltophilia.

One-Pot Assay for Rapid Detection of Stenotrophomonas maltophilia by RPA-CRISPR/Cas12a.

Stenotrophomonas maltophilia (S. maltophilia, SMA) is a common opportunistic pathogen that poses a serious threat to the food industry and human health. Traditional detection methods for SMA are time-consuming, have low detection rates, require complex and expensive equipment and professional technical personnel for operation, and are unsuitable for on-site detection. Therefore, establishing an efficient on-site detection method has great significance in formulating appropriate treatment strategies and ensuring food safety. In the present study, a rapid one-pot detection method was established for SMA using a combination of Recombinase Polymerase Amplification (RPA) and CRISPR/Cas12a, referred to as ORCas12a-SMA (one-pot RPA-CRISPR/Cas12a platform). In the ORCas12a-SMA detection method, all components were added into a single tube simultaneously to achieve one-pot detection and address the problems of nucleic acid cross-contamination and reduced sensitivity caused by frequent cap opening during stepwise detection. The ORCas12a-SMA method could detect at least 3 × 10° copies·µL-1 of SMA genomic DNA within 30 min at 37 °C. Additionally, this method exhibited sensitivity compared to the typical two-step RPA-CRISPR/Cas12a method. Overall, the ORCas12a-SMA detection offered the advantages of rapidity, simplicity, high sensitivity and specificity, and decreased need for complex large-scale instrumentation. This assay is the first application of the one-pot platform based on the combination of RPA and CRISPR/Cas12a in SMA detection and is highly suitable for point-of-care testing. It helps reduce losses in the food industry and provides assistance in formulating timely and appropriate antimicrobial treatment plans.

Atypical Presentation of Stenotrophomonas maltophilia Stomatitis Post COVID-19 in an Immunocompetent Adolescent.

Stenotrophomonas maltophilia (S. maltophilia) is a rare, multi-drug-resistant opportunistic bacteria that typically causes serious infections in immunocompromised and hospitalized patients, often leading to fatal pneumonia or bacteremia. We present the case of a healthy 15-year-old immunocompetent female who developed severe oral ulcers due to S. maltophilia following a recent COVID-19 infection. To our knowledge, this is the first reported case of S. maltophilia manifesting in this manner after COVID-19. Scrapes from the oral lesions were collected and cultured, confirming the infection.The CBC and immunoglobulin reports revealed mildly elevated IgA and platelet levels, with no evidence of immunodeficiency.The patient was treated with trimethoprim/sulfamethoxazole (TMP-SMX) based on culture sensitivity, and she responded well to treatment. She was referred to an infectious disease specialist for further monitoring. COVID-19 has recently been implicated in many unusual presentations, associations, and syndromes. One of the most supported theories about COVID-19 is its association with a transient immunodeficient state or a generalized state of immune system dysregulation that can compromise both innate and adaptive immunity. This case supports that theory, as no other apparent etiology for such an otherwise opportunistic infection was identified. The recognition of such atypical infections in previously healthy individuals, particularly post COVID-19, highlights the importance of sharpening clinical vigilance and considering opportunistic pathogens in differential diagnoses. Further research is warranted to explore the potential link between COVID-19 and the susceptibility to rare opportunistic infections, which may guide future clinical practices.

Substrate preference, RNA binding and active site versatility of Stenotrophomonas maltophilia nuclease SmNuc1, explained by a structural study.

Nucleases of the S1/P1 family have important applications in biotechnology and molecular biology. We have performed structural analyses of SmNuc1 nuclease from Stenotrophomonas maltophilia, including RNA cleavage product binding and mutagenesis in a newly discovered flexible Arg74-motif, involved in substrate binding and product release and likely contributing to the high catalytic rate. The Arg74Gln mutation shifts substrate preference towards RNA. Purine nucleotide binding differs compared to pyrimidines, confirming the plasticity of the active site. The enzyme-product interactions indicate a gradual, stepwise product release. The activity of SmNuc1 towards c-di-GMP in crystal resulted in a distinguished complex with the emerging product 5'-GMP. This enzyme from an opportunistic pathogen relies on specific architecture enabling high performance under broad conditions, attractive for biotechnologies.

Colonisation by multidrug-resistant organisms in health workers in primary care: narrow spectrum oral antimicrobials are a risk factor.

BACKGROUND: Limited information exists on carriage of multidrug-resistant organisms (MDRO) by health workers (HWs) in primary care settings. This study aims to determine the prevalence of MDRO carriage among HWs in primary care and to identify associated risk factors. METHODS: A cross-sectional study was conducted across all 12 primary care units in São Caetano do Sul-SP, Brazil, from October to December 2023. Self-collected samples (nasal, oropharyngeal, and inguinal) were obtained. Environment cultures (potable water, sewage and stream water) were evaluated. Stenotrophomonas maltophilia isolates (human and environmental) were typed. RESULTS: The study included 265/288 (92%) of HWs in primary care teams, mostly women with a median age of 47 years (IQR 38-57); 78% had no comorbidities. MDRO colonisation was found in 8.7% (23 HWs). The following bacteria were found: S. maltophilia (n = 9; 3.4%) in inguinal swabs; methicillin-resistant Staphylococcus aureus (n = 8; 3%) from all sites; extended-spectrum ß-lactamase-producing bacteria (n = 5; 2%) in inguinal swabs; and vancomycin-resistant enterococci in an inguinal swab (n = 1; 0.4%). Previous antibiotic use was significantly associated with MDRO colonisation (OR 2.91, 95% CI 1.19-7.09, p = 0.018), mainly narrow spectrum oral beta-lactams and macrolides. S. malthophilia was polyclonal and human and environmental isolates differed. CONCLUSION: Colonisation by MRSA, VRE, and ESBL-producing bacteria was low; however, 4% were surprisingly colonized by polyclonal S. maltophilia. This pathogen may also suggest using narrow-spectrum rather than the expected broad-spectrum antimicrobials. Antibiotic use was the only risk factor found, mainly with oral narrow-spectrum drugs.

Isolation, characterization and Genomic analysis of BUCT627: a lytic bacteriophage targeting Stenotrophomonas maltophilia.

Stenotrophomonas infections pose significant therapeutic challenges due to escalating resistance to antibiotics and chemotherapeutic agents. Phages offer a potential solution by virtue of their specific bacterial targeting capabilities. In this study, we isolated a new Stenotrophomonas bacteriophage, named BUCT627, from hospital sewage. Phage BUCT627 exhibited a 30-minute latent period and demonstrated a burst size of 46 PFU/cell. Remarkably, this phage displayed robust stability across a wide pH range (pH 3-13) and exhibited resilience under varying thermal conditions. The receptor of phage BUCT627 on S. maltophilia No.826 predominantly consist of surface proteins. The complete genome of phage BUCT627 is a 61 860-bp linear double-stranded DNA molecule with a GC content of 56.3%, and contained 99 open reading frames and two tRNAs. Notably, no antibiotic resistance, toxin, virulence related genes or lysogen-formation gene clusters was identified in BUCT627. Transmission electron microscopy and phylogeny analysis indicated that this phage was a new member within the Siphoviridae family. The results of this study will enhance our understanding of phage diversity and hold promise for the development of alternative therapeutic strategies against Stenotrophomonas maltophilia infections.

Microbiological Quality and Antibiotic Resistance of Relevant Bacteria from Horsemeat.

The aim of this work was to assess the microbiological safety and quality of horsemeat. A total of 19 fresh horsemeat samples were analysed. Mesophile counts were 4.89 ± 1.08 log CFU/g, and Enterobacteriaceae, Staphylococcus spp., and enterococci were only isolated from 36.84%, 21.05%, and 15.79% of the samples, respectively. Neither Staphylococcus aureus nor Escherichia coli were found in any sample. Listeria spp. and Listeria monocytogenes were detected in 31.58% and 21.05% of the samples, respectively. Campylobacter jejuni was not detected in any sample. The dominant bacteria were lactic acid bacteria. Seven different Staphylococcus spp. were identified, the most common being S. delphini, S. saprophyticus, and S. warneri. S. delphini showed resistance against mupirocin and cefoxitin. All the L. monocytogenes strains showed resistance against ampicillin, cefotaxime, and oxacillin. Multi-resistant Yersinia enterocolitica, Stenotrophomonas maltophilia, and Vagococcus. fluvialis strains were found, with resistance to 11, 7, and 8 antibiotics, respectively, causing significant concern. Therefore, specific actions should be taken to decrease the contamination of horsemeat.

Description, clinical impact and early outcome of S. maltophilia respiratory tract infections after lung transplantation, A retrospective observational study.

BACKGROUND AND RESEARCH QUESTION: S. maltophilia infections are associated with significant morbidity and mortality. Little is known regarding its presentation, management, and outcome in lung transplant recipients. STUDY DESIGN AND METHODS: This retrospective case control study reviewed S. maltophilia respiratory tract infection in lung transplant recipients (01/01/2011-31/01/2020) and described the clinical, microbiological and outcome characteristics matched with lung transplant recipients without respiratory tract infection. RESULTS AND INTERPRETATION: We identified 63 S. maltophilia infections in lung transplant recipients. Among them none were colonized before transplantation. Infections occurred a median of 177 (IQR: 45- 681) days post transplantation. Fifty-four (85.7 %) patients received trimethoprim-sulfamethoxazole (400/80 mg three times a week) to prevent Pneumocystis jirovecii pneumonia (PJP). S. maltophilia strains were susceptible to trimethoprim-sulfamethoxazole, levofloxacin, minocycline and ceftazidime in respectively 85.7 %, 82.5 %, 96.8 % and 34.9 % of cases. Median duration of treatment was 9 days (IQR 7-11.5). Clinical and microbiological recurrence were observed in respectively 25.3 % and 39.7 % of cases. Combination therapy was not associated with a decrease in the risk of recurrence and did not prevent the emergence of resistance. S. maltophilia respiratory tract infection was associated with a decline in FEV-1 at one year. CONCLUSION: S. maltophilia is an important cause of lower respiratory tract infection in lung transplant recipients. Trimethoprim-sulfamethoxazole use as prophylaxis for PJP doesn't prevent S. maltophilia infection among lung transplant recipients. Levofloxacin and trimethoprim-sulfamethoxazole appear to be the two molecules of choice for the treatment of these infections and new antibiotic strategies (cefiderocol, aztreonam/avibactam) are currently being evaluated for multi-resistant S. maltophilia infections.

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

BACKGROUND: 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 ß-lactamase-producing Enterobacterales (ESBL-E), AmpC ß- 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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/.

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.

Stenotrophomonas maltophilia: The Landscape in Critically Ill Patients and Optimising Management Approaches.

The aim of this review is to synthesise the key aspects of the epidemiology, current microbiological diagnostic challenges, antibiotic resistance rates, optimal antimicrobial management, and most effective prevention strategies for Stenotrophomonas maltophilia (SM) in the intensive care unit (ICU) population. In recent years, resistance surveillance data indicate that SM accounts for less than 3% of all healthcare-associated infection strains, a percentage that doubles in the case of ventilator-associated pneumonia (VAP). Interestingly, SM ranks as the third most isolated non-glucose fermenter Gram-negative bacilli (NFGNB). Although this NFGNB genus has usually been considered a bystander and colonising strain, recently published data warn about its potential role as a causative pathogen of severe infections, particularly pneumonia and bloodstream infections (BSI), not only for the classical immunocompromised susceptible host patients but also for critically ill ones even without overt immunosuppression. Indeed, it has been associated with crude 28-day mortality as high as 54.8%, despite initial response following targeted therapy. Additionally, alongside its intrinsic resistance to a wide range of common antimicrobials, various worldwide and local surveillance studies raise concerns about an increase in ICU settings regarding resistance to first-line drugs such as cotrimoxazole or tigecycline. This scenario alerts ICU physicians to the need to reconsider the best stewardship approach when SM is isolated in obtained samples from critically ill patients. Despite the coverage of this multidrug-resistant bacterium (MDRB) provided by some traditional and a non-negligible number of current pipeline antimicrobials, an ecological and cost-effective strategy is needed in the present era.

Stenotrophomonas maltophilia-associated odontogenic cerebral abscess in an immunocompetent patient: A case report.

Key Clinical Message: Stenotrophomonas maltophilia can cause rare odontogenic brain abscesses in immunocompetent patients, highlighting the importance of considering uncommon pathogens in central nervous system infections. With only three reported cases of cerebral abscesses and one pituitary abscess caused by this microorganism, tailored diagnostic methods and individualized treatment regimens are crucial for accurate management. Abstract: Brain abscesses present diagnostic and therapeutic challenges, with Stenotrophomonas maltophilia infections being exceptionally rare in the central nervous system. We present a case of odontogenic brain abscesses caused by S. maltophilia in an immunocompetent patient, highlighting the rarity and complexity of such infections. A 66-year-old male presented with spatial-temporal disorientation and left-sided weakness. Radiological investigations revealed an expansive lesion in the right posterior frontal region. A craniotomy and drainage were performed, identifying S. maltophilia in the purulent material. The patient responded well to tailored antibiotic therapy. S. maltophilia-related central nervous system infections are infrequent, emphasizing the need for a heightened clinical suspicion in atypical cases. This case contributes to the literature, emphasizing the importance of a multidisciplinary approach for successful diagnosis and management.

Characterization and genomic analysis of a lytic Stenotrophomonas maltophilia short-tailed phage A1432 revealed a new genus of the family Mesyanzhinovviridae.

Stenotrophomonas maltophilia (S. maltophilia) is an emerging opportunistic pathogen that exhibits resistant to a majority of commonly used antibiotics. Phages have the potential to serve as an alternative treatment for S. maltophilia infections. In this study, a lytic phage, A1432, infecting S. maltophilia YCR3A-1, was isolated and characterized from a karst cave. Transmission electron microscopy revealed that phage A1432 possesses an icosahedral head and a shorter tail. Phage A1432 demonstrated a narrow host range, with an optimal multiplicity of infection of 0.1. The one-step growth curve indicated a latent time of 10 min, a lysis period of 90 min, a burst size of 43.2 plaque-forming units per cell. In vitro bacteriolytic activity test showed that phage A1432 was capable to inhibit the growth of S. maltophilia YCR3A-1 in an MOI-dependent manner after 2 h of co-culture. BLASTn analysis showed that phage A1432 genome shares the highest similarity (81.46%) with Xanthomonas phage Xoo-sp2 in the NCBI database, while the query coverage was only 37%. The phage contains double-stranded DNA with a genome length of 61,660 bp and a GC content of 61.92%. It is predicted to have 79 open reading frames and one tRNA, with no virulence or antibiotic resistance genes. Phylogenetic analysis using terminase large subunit and DNA polymerase indicated that phage A1432 clustered with members of the Bradleyvirinae subfamily but diverged into a distinct branch. Further phylogenetic comparison analysis using Average Nucleotide Identity, proteomic phylogenetic analysis, genomic network analysis confirmed that phage A1432 belongs to a novel genus within the Bradleyvirinae subfamily, Mesyanzhinovviridae family. Additionally, phylogenetic analysis of the so far isolated S. maltophilia phages revealed significant genetic diversity among these phages. The results of this research will contribute valuable information for further studies on their morphological and genetic diversity, will aid in elucidating the evolutionary mechanisms that give rise to them.

A sbiT-sbiRS-gloIo regulatory circuit is involved in oxidative stress tolerance of Stenotrophomonas maltophilia.

The sbiT-sbiR-sbiS operon of Stenotrophomonas maltophilia encodes an inner-membrane protein SbiT and a SbiS-SbiR two-component regulatory system. A sbiT mutant displayed a growth defect in LB agar. Mechanism studies revealed that sbiT deletion resulted in SbiSR activation and gloIo upregulation, which increased intracellular ROS level and caused growth defect.

Antibacterial potential of Stenotrophomonas maltophilia complex cystic fibrosis isolates.

Over 160,000 people worldwide suffer from cystic fibrosis (CF), a genetic condition that causes mucus to accumulate in internal organs. Lung decline is a significant health burden for people with CF (pwCF), and chronic bacterial pulmonary infections are a major cause of death. Stenotrophomonas maltophilia complex (Smc) is an emerging, multidrug-resistant CF pathogen that can cause pulmonary exacerbations and result in higher mortality. However, little is known about the antagonistic interactions that occur between Smc isolates from pwCF and competitor bacteria. We obtained 13 Smc isolates from adult and pediatric pwCF located in the United States or Australia. We co-cultured these isolates with Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli. We also performed whole-genome sequencing of these Smc isolates and compared their genomes using average nucleotide identity analyses. We observed that some Smc CF isolates can engage in antagonistic interactions with P. aeruginosa and S. aureus but recovered a substantial number of P. aeruginosa and S. aureus cells following co-cultures with all tested Smc isolates. By contrast, we discovered that most Smc CF isolates display strong antibacterial properties against E. coli cells and reduce recovery below detectable limits. Finally, we demonstrate that Smc CF strains from this study belong to diverse phylogenetic lineages. IMPORTANCE: Antagonism toward competitor bacteria may be important for the survival of Stenotrophomonas maltophilia complex (Smc) in external environments, for the elimination of commensal species and colonization of upper respiratory tracts to enable early infections, and for competition against other pathogens after establishing chronic infections. These intermicrobial interactions could facilitate the acquisition of Smc by people with cystic fibrosis from environmental or nosocomial sources. Elucidating the mechanisms used by Smc to eliminate other bacteria could lead to new insights into the development of novel treatments.

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.

Omics-Based Investigation on Mechanisms Controlling Cellular Internalization of Keratin Monomers during Biodegradation by Stenotrophomonas maltophilia DHHJ.

INTRODUCTION: The global poultry industry produces millions of tons of waste feathers every year, which can be bio-degraded to make feed, fertilizer, and daily chemicals. However, feather bio-degradation is a complex process that is not yet fully understood. This results in low degradation efficiency and difficulty in industrial applications. Omics-driven system biology research offers an effective solution to quickly and comprehensively understand the molecularmechanisms involved in a metabolic pathway. METHODS: In the early stage of this process, feathers are hydrolyzed into water-soluble keratin monomers. In this study, we used high-throughput RNA-seq technology to analyze the genes involved in the internalization and degradation of keratin monomers in Stenotrophomonas maltophilia DHHJ strain cells. Moreover, we used Co-IP with LC-MS/MS technology to search for proteins that interact with recombinant keratin monomers. RESULTS: We discovered TonB transports and molecular chaperones associating with the keratin monomer, which may play a crucial role in the transmembrane transport of keratin. Meanwhile, multiple proteases belonging to distinct families were identified as binding partners of keratin monomers, among which ATPases associated with diverse cellular activity (AAA+) family proteases are overrepresented. Four genes, including JJL50_15620, JJL50_17955 (TonB-dependent receptors), JJL50_03260 (ABC transporter ATP-binding protein), and JJL50_20035 (ABC transporter substrate-binding protein), were selected as representatives for determining their expressions under different culture conditions using qRT-PCR, and they were found to be upregulated in response to keratin degradation consistent with the data from RNA-seq and Co-IP. CONCLUSION: This study highlights the complexity of keratin biodegradation in S. maltophilia DHHJ, in which multiple pathways are involved such as protein folding, protein transport, and several protease systems. Our findings provide new insights into the mechanism of feather degradation.