Novel case of combination antibiotic therapy for treatment of a complicated polymicrobial urinary tract infection with one organism harboring a metallo-ß-lactamase (MBL) in a pregnant patient.

Carbapenem resistance due to metallo-beta-lactamases (MBLs) is a global phenomenon and an important challenge for antibiotic therapy (Boyd et al., 2020 [1]). While previous reports have demonstrated both in vitro and in vivo synergy using the combination of ceftazidime-avibactam and aztreonam against Stenotrophomonas maltophilia, an MBL-harboring organism, this treatment strategy has not been reported during pregnancy (Mojic et al., 2017 [2], [3], Mojica et al., 2016 [4], Alexander et al., 2020 [5]). We describe a 33-year-old pregnant female with polymicrobial, bilateral pyelonephritis caused by Stenotrophomonas maltophilia and other gram-negative bacteria. The organisms were eradicated with the combination of ceftazidime-avibactam and aztreonam followed by successful delivery with no observed adverse effects in either mother or child post-partum.

Evolution of Resistance against Ciprofloxacin, Tobramycin, and Trimethoprim/Sulfamethoxazole in the Environmental Opportunistic Pathogen Stenotrophomonas maltophilia.

Stenotrophomonas maltophilia is an opportunistic pathogen that produces respiratory infections in immunosuppressed and cystic fibrosis patients. The therapeutic options to treat S. maltophilia infections are limited since it exhibits resistance to a wide variety of antibiotics such as ß-lactams, aminoglycosides, tetracyclines, cephalosporins, macrolides, fluoroquinolones, or carbapenems. The antibiotic combination trimethoprim/sulfamethoxazole (SXT) is the treatment of choice to combat infections caused by S. maltophilia, while ceftazidime, ciprofloxacin, or tobramycin are used in most SXT-resistant infections. In the current study, experimental evolution and whole-genome sequencing (WGS) were used to examine the evolutionary trajectories of S. maltophilia towards resistance against tobramycin, ciprofloxacin, and SXT. The genetic changes underlying antibiotic resistance, as well as the evolutionary trajectories toward that resistance, were determined. Our results determine that genomic changes in the efflux pump regulatory genes smeT and soxR are essential to confer resistance to ciprofloxacin, and the mutation in the rplA gene is significant in the resistance to tobramycin. We identified mutations in folP and the efflux pump regulator smeRV as the basis of SXT resistance. Detailed and reliable knowledge of ciprofloxacin, tobramycin, and SXT resistance is essential for safe and effective use in clinical settings. Herein, we were able to prove once again the extraordinary ability that S. maltophilia has to acquire resistance and the importance of looking for alternatives to combat this resistance.

Stenotrophomonas maltophilia Isolated from the Gut Symbiotic Community of the Plastic-Eating Tenebrio molitor.

Polyvinyl chloride (PVC) waste is a major environmental challenge. In this study, we found that a PVC-eating insect, Tenebrio molitor, could survive by consuming PVC as a dietary supplement. To understand the gut symbiotic community, metagenomic analysis was performed to reveal the biodiversity of a symbiotic community in the midgut of Tenebrio molitor. Among them, seven genera were enriched from the midgut of the insect under culture conditions with PVC as carbon source. A strain of Stenotrophomonas maltophilia was isolated from the midgut symbiotic community of the plastic-eating Tenebrio molitor. To unravel the functional gene for the biodegradation enzyme, we sequenced the whole genome of Stenotrophomonas maltophilia and found that orf00390, annotated as a hydrolase, was highly expressed in the PVC culture niche.

HemU and TonB1 contribute to hemin acquisition in Stenotrophomonas maltophilia.

Introduction: The hemin acquisition system is composed of an outer membrane TonB-dependent transporter that internalizes hemin into the periplasm, periplasmic hemin-binding proteins to shuttle hemin, an inner membrane transporter that transports hemin into the cytoplasm, and cytoplasmic heme oxygenase to release iron. Fur and HemP are two known regulators involved in the regulation of hemin acquisition. The hemin acquisition system of Stenotrophomonas maltophilia is poorly understood, with the exception of HemA as a TonB-dependent transporter for hemin uptake. Methods: Putative candidates responsible for hemin acquisition were selected via a homolog search and a whole-genome survey of S. maltophilia. Operon verification was performed by reverse transcription-polymerase chain reaction. The involvement of candidate genes in hemin acquisition was assessed using an in-frame deletion mutant construct and iron utilization assays. The transcript levels of candidate genes were determined using quantitative polymerase chain reaction. Results: Smlt3896-hemU-exbB2-exbD2-tonB2 and tonB1-exbB1-exbD1a-exbD1b operons were selected as candidates for hemin acquisition. Compared with the parental strain, hemU and tonB1 mutants displayed a defect in their ability to use hemin as the sole iron source for growth. However, hemin utilization by the Smlt3896 and tonB2 mutants was comparable to that of the parental strain. HemA expression was repressed by Fur in iron-replete conditions and derepressed in iron-depleted conditions. HemP negatively regulated hemA expression. Like hemA, hemU was repressed by Fur in iron-replete conditions; however, hemU was moderately derepressed in response to iron-depleted stress and fully derepressed when hemin was present. Unlike hemA and hemU, the TonB1-exbB1-exbD1a-exbD1b operon was constitutively expressed, regardless of the iron level or the presence of hemin, and Fur and HemP had no influence on its expression. Conclusion: HemA, HemU, and TonB1 contribute to hemin acquisition in S. maltophilia. Fur represses the expression of hemA and hemU in iron-replete conditions. HemA expression is regulated by low iron levels, and HemP acts as a negative regulator of this regulatory circuit. HemU expression is regulated by low iron and hemin levels in a hemP-dependent manner.

Correlation between Stenotrophomonas maltophilia incidence and systemic antibiotic use: A 10-year retrospective, observational study in Hungary.

Extensive use of carbapenems may lead to selection pressure for Stenotrophomonas maltophilia (SM) in hospital environments. The aim of our study was to assess the possible association between systemic antibiotic use and the incidence of SM. A retrospective, observational study was carried out in a tertiary-care hospital in Hungary, between January 1st 2010 and December 31st 2019. Incidence-density for SM and SM resistant to trimethoprim-sulfamethoxazole (SXT) was standardized for 1000 patient-days, while systemic antibiotic use was expressed as defined daily doses (DDDs) per 100 patient-days. Mean incidence density for SM infections was 0.42/1000 patient-days; 11.08% were were resistant to SXT, the mean incidence density for SXT-resistant SM was 0.047/1000 patient-days. Consumption rate for colistin, glycopeptides and carbapenems increased by 258.82, 278.94 and 372.72% from 2010 to 2019, respectively. Strong and significant positive correlations were observed with the consumption of carbapenems (r: 0.8759; P < 0.001 and r: 0.8968; P < 0.001), SXT (r: 0.7552; P = 0.011 and r: 0.7004; P = 0.024), and glycopeptides (r: 0.7542; P = 0.012 and r: 0.8138; P < 0.001) with SM and SXT-resistant SM incidence-density/1000 patient-days, respectively. Implementation of institutional carbapenem-sparing strategies are critical in preserving these life-saving drugs, and may affect the microbial spectrum of infections in clinical settings.

Surgically-Induced Necrotizing Scleritis After Scleral Buckling With Stenotrophomonas maltophilia Infection.

Surgically induced necrotizing scleritis (SINS) is a rare inflammatory disease of the sclera that occurs following ocular surgery, specifically pterygium surgery and scleral buckling. Here, we report a case of SINS in a 78-year-old female patient after segmental scleral buckling for rhegmatogenous retinal detachment. The retina was restored after scleral buckling, and the postoperative course was uneventful. However, the patient developed ocular discharge and conjunctival hyperemia, indicating infection, after two months. The sclera became thinner and intraocular inflammation developed after buckle removal. Stenotrophomonas maltophilia was isolated from the ocular discharge, and the patient was treated with antibacterial agents susceptible to the bacteria. However, her symptoms persisted, and corrected visual acuity decreased from 20/25 to 20/1000. Oral steroid treatment was initiated because of the suspicion of SINS. Intraocular inflammation gradually subsided, the thin sclera was covered by conjunctival tissue, and the patient's corrected visual acuity improved to 20/32, which stabilized her condition. Infection with Stenotrophomonas maltophilia after scleral buckling is extremely rare, and SINS development in such cases is unprecedented.

The Mla system and its role in maintaining outer membrane barrier function in Stenotrophomonas maltophilia.

Stenotrophomonas maltophilia are ubiquitous Gram-negative bacteria found in both natural and clinical environments. It is a remarkably adaptable species capable of thriving in various environments, thanks to the plasticity of its genome and a diverse array of genes that encode a wide range of functions. Among these functions, one notable trait is its remarkable ability to resist various antimicrobial agents, primarily through mechanisms that regulate the diffusion across cell membranes. We have investigated the Mla ABC transport system of S. maltophilia, which in other Gram-negative bacteria is known to transport phospholipids across the periplasm and is involved in maintaining outer membrane homeostasis. First, we structurally and functionally characterized the periplasmic substrate-binding protein MlaC, which determines the specificity of this system. The predicted structure of the S. maltophilia MlaC protein revealed a hydrophobic cavity of sufficient size to accommodate the phospholipids commonly found in this species. Moreover, recombinant MlaC produced heterologously demonstrated the ability to bind phospholipids. Gene knockout experiments in S. maltophilia K279a revealed that the Mla system is involved in baseline resistance to antimicrobial and antibiofilm agents, especially those with divalent-cation chelating activity. Co-culture experiments with Pseudomonas aeruginosa also showed a significant contribution of this system to the cooperation between both species in the formation of polymicrobial biofilms. As suggested for other Gram-negative pathogenic microorganisms, this system emerges as an appealing target for potential combined antimicrobial therapies.

Risk factors for mortality in Stenotrophomonas maltophilia bacteremia - a meta-analysis.

BACKGROUND: Stenotrophomonas maltophilia (S. maltophilia) is a nosocomial pathogen causing life-threatening invasive infections with a high mortality rate in some patient populations, especially those who are severely ill or immunocompromised. There is a need for data on mortality in patients with S. maltophilia bacteremia. OBJECTIVE: In this meta-analysis, we aimed to investigate risk factors for mortality in S. maltophilia bacteremia. METHODS: Studies comparing patients who died from S. maltophilia bacteremia with patients who survived were considered for inclusion. Studies were included if they reported one or more risk factors for mortality. Mortality risk factors included clinical predisposing factors, predisposing comorbidities and appropriateness of antibiotic therapy. RESULTS: Nineteen studies with 1248 patients were included in the meta-analysis. Five hundred and six (40.5%) patients died. The following risk factors for mortality were identified: ICU admission, septic shock, need for mechanical ventilation, indwelling central venous catheter, neutropenia, comorbid hematological malignancies, chronic kidney disease, inappropriate antimicrobial therapy and prior antibiotic use. CONCLUSIONS: Appropriate antimicrobial therapy had a protective effect against mortality in S. maltophilia bacteremia. Indwelling central venous catheter, neutropenia, hematological malignancies and chronic kidney disease were also risk factors for mortality.

Validation of a Stenotrophomonas maltophilia bloodstream infection prediction score in the hematologic malignancy population.

Stenotrophomonas maltophilia (SM) bloodstream infections (BSIs) contribute to significant mortality in hematologic malignancy (HM) and hematopoietic stem cell transplantation (HSCT) patients. A risk score to predict SM BSI could reduce time to appropriate antimicrobial therapy (TTAT) and improve patient outcomes. A single center cohort study of hospitalized adults with HM/HSCT was conducted. Patients had ≥ 1 blood culture with a Gram-negative (GN) organism. A StenoSCORE was calculated for each patient. The StenoSCORE2 was developed using risk factors for SM BSI identified via logistic regression. Receiver operating characteristic (ROC) curves were plotted. Sensitivity and specificity for the StenoSCORE and StenoSCORE2 were calculated. Thirty-six SM patients and 534 non-SM patients were assessed. A StenoSCORE ≥ 33 points was 80% sensitive, 68% specific, and accurately classified 69% of GN BSIs. StenoSCORE2 variables included acute leukemia, prolonged neutropenia, mucositis, ICU admission, recent meropenem and/or cefepime exposure. The StenoSCORE2 performed better than the StenoSCORE (ROC AUC 0.84 vs. 0.77). A StenoSCORE2 ≥ 4 points was 86% sensitive, 76% specific, and accurately classified 77% of GN BSIs. TTAT was significantly longer for patients with SM BSI compared with non-SM BSI (45.16 h vs. 0.57 h; p < 0.0001). In-hospital and 28-day mortality were significantly higher for patients with SM BSI compared to non-SM BSI (58.3% vs. 18.5% and 66.7% vs. 26.4%; p-value < 0.0001). The StenoSCORE and StenoSCORE2 performed well in predicting SM BSIs in patients with HM/HSCT and GN BSI. Clinical studies evaluating whether StenoSCORE and/or StenoSCORE2 implementation improves TTAT and clinical outcomes are warranted.

Stenotrophomonas maltophilia neonatal sepsis: a case report.

BACKGROUND: Stenotrophomonas maltophilia is a gram-negative bacteria known for causing opportunistic and nosocomial infections in humans. S. maltophilia is an emerging pathogen of concern due to it's increasing prevalence, diverse disease spectrum, intrinsic multi-drug resistance and high mortality rates in immunocompromised individuals. S. maltophilia is a rare cause of neonatal sepsis associated with significant morbidity and mortality. The bacterium's multi-drug resistance poses a considerable challenge for treatment, with various mechanisms contributing to its resistance. CASE PRESENTATION: We report a case involving a 40-h-old male African neonate who exhibited symptoms of neonatal sepsis. The blood culture revealed Stenotrophomonas maltophilia, which was sensitive to ciprofloxacin and gentamicin but resistant to other antibiotics. Lumbar puncture for CSF could not be done because the father declined. We treated the newborn with the empirical first-line antibiotics as per the national guideline intravenous ampicillin and gentamicin for six days, and the child recovered fully with a repeated negative blood culture. CONCLUSIONS: This report describes a neonatal sepsis case caused by S. maltophilia, a multi-drug resistant bacteria and a rare cause of neonatal sepsis. We report that early detection of the bacterial and antimicrobial management based on local antibiogram data may be essential for successful patient's management.

Global mapping of antibiotic resistance rates among clinical isolates of Stenotrophomonas maltophilia: a systematic review and meta-analysis.

INTRODUCTION: Infections caused by Stenotrophomonas maltophilia are clinically important due to its intrinsic resistance to a broad range of antibiotics. Therefore, selecting the most appropriate antibiotic to treat S. maltophilia infection is a major challenge. AIM: The current meta-analysis aimed to investigate the global prevalence of antibiotic resistance among S. maltophilia isolates to the develop more effective therapeutic strategies. METHOD: A systematic literature search was performed using the appropriate search syntax after searching Pubmed, Embase, Web of Science and Scopus databases (May 2023). Statistical analysis was performed using Pooled and the random effects model in R and the metafor package. A total of 11,438 articles were retrieved. After a thorough evaluation, 289 studies were finally eligible for inclusion in this systematic review and meta-analysis. RESULT: Present analysis indicated that the highest incidences of resistance were associated with doripenem (97%), cefoxitin (96%), imipenem and cefuroxime (95%), ampicillin (94%), ceftriaxone (92%), aztreonam (91%) and meropenem (90%) which resistance to Carbapenems is intrinsic. The lowest resistance rates were documented for minocycline (3%), cefiderocol (4%). The global resistance rate to TMP-SMX remained constant in two periods before and after 2010 (14.4% vs. 14.6%). A significant increase in resistance to tigecycline and ceftolozane/tazobactam was observed before and after 2010. CONCLUSIONS: Minocycline and cefiderocol can be considered the preferred treatment options due to low resistance rates, although regional differences in resistance rates to other antibiotics should be considered. The low global prevalence of resistance to TMP-SMX as a first-line treatment for S. maltophilia suggests that it remains an effective treatment option.

Case series: Stenotrophomonas maltophilia in pediatric oncology patients.

BACKGROUND: Stenotrophomonas maltophilia is a bacterial pathogen that can be fatal in hospitalized and immunocompromised patients with mortality as high as 69%. Pediatric cancer patients often have risk factors that are common for this infection, making them particularly susceptible. Managing S. maltophilia is especially challenging as it has inherent resistance to several antibiotics. Furthermore, soft tissue infections in neutropenic patients may deviate from the typical clinical presentation of S. maltophilia. CASE DETAILS: This case series describes an in-depth examination of three cases involving immunocompromised pediatric patients with S. maltophilia infections. Each case exhibited a distinct clinical presentation, encompassing infection of the blood, lung, and skin, which highlights the variability in which S. maltophilia manifests in immunocompromised pediatric patients. These patients were treated at MD Anderson Cancer Center (MDACC) from 2020 to 2023, unfortunately resulting in fatality. CONCLUSIONS: The study aims to provide valuable insights and guidance for the management of patients with S. maltophilia infections. Emphasizing a heightened clinical suspicion will potentially lead to early initiation of directed therapy against S. maltophilia. Timely intervention may play a pivotal role in improving patient outcomes and reduce further burden to the healthcare system.

Bacterial heat shock protein: A new crosstalk between T lymphocyte and macrophage via JAK2/STAT1 pathway in bloodstream infection.

Bloodstream infection (BSI) refers to the infection of blood by pathogens. Severe immune response to BSI can lead to sepsis, a systemic infection leading to multiple organ dysfunction, coupled with drug resistance, mortality, and limited clinical treatment options. This work aims to further investigate the new interplay between bacterial exocrine regulatory protein and host immune cells in the context of highly drug-resistant malignant BSI. Whether interfering with related regulatory signaling pathways can reverse the inflammatory disorder of immune cells. In-depth analysis of single-cell sequencing results in Septic patients for potential immunodeficiency factors. Analysis of key proteins enriched by host cells and key pathways using proteomics. Cell models and animal models validate the pathological effects of DnaK on T cells, MAITs, macrophages, and osteoclasts. The blood of patients was analyzed for the immunosuppression of T cells and MAITs. We identified that S. maltophilia-DnaK was enriched in immunodeficient T cells. The activation of the JAK2/STAT1 axis initiated the exhaustion of T cells. Septic patients with Gram-negative bacterial infections exhibited deficiencies in MAITs, which correspond to IFN-γ. Cellular and animal experiments confirmed that DnaK could facilitate MAIT depletion and M1 polarization of macrophages. Additionally, Fludarabine mitigated M1 polarization of blood, liver, and spleen in mice. Interestingly, DnaK also repressed osteoclastogenesis of macrophages stimulated by RANKL. S.maltophilia-DnaK prompts the activation of the JAK2/STAT1 axis in T cells and the M1 polarization of macrophages. Targeting the DnaK's crosstalk can be a potentially effective approach for treating the inflammatory disorder in the broad-spectrum drug-resistant BSI.

Development of a duplex droplet digital PCR assay for the detection of Burkholderia cepacia complex and Stenotrophomonas maltophilia in bloodstream infections.

Burkholderia cepacia complex (BCC) and Stenotrophomonas maltophilia are nosocomial pathogens that cause various infections and exhibit high resistance to multiple antimicrobial agents. In this study, we aimed to develop a duplex droplet digital PCR (ddPCR) assay for detecting BCC and S. maltophilia in bloodstream infections. We optimized the experimental conditions by setting the annealing temperature to 51°C and determining the optimal concentrations of primers and probes, as well as the thermal cycle numbers. The feasibility of the duplex ddPCR reaction system with the optimal conditions was established and verified through parallel reactions with reference strains of BCC and S. maltophilia. The specificity of the assay, tested with 33 reference strains, was found to be 100%. The duplex ddPCR assay demonstrated good repeatability and could detect as low as 5.35 copies/reaction of BCC and 7.67 copies/reaction of S. maltophilia. This level of sensitivity was consistent in the simulated blood and blood bottle samples. We compared nucleic acid extraction methods and found that the Chelex-100 boiling method and kit extraction method exhibited similar detection sensitivity, suggesting the potential application of the Chelex-100 boiling method in the ddPCR assay. In the clinical samples, the duplex ddPCR assay accurately detected BCC and S. maltophilia in 58 cases. In conclusion, our study successfully developed a duplex ddPCR assay that provides accurate and convenient detection of BCC and S. maltophilia in bloodstream infections.IMPORTANCEBurkholderia cepacia complex (BCC) and Stenotrophomonas maltophilia are implicated in a wide range of infections, including bloodstream infections (BSIs), pneumonia, and meningitis, and often exhibit high intrinsic resistance to multiple antimicrobial agents, limiting therapeutic options. The gold standard for diagnosing bloodstream infections remains blood culture. However, current blood culture detection and positivity rates do not meet the "rapid diagnosis" required for the diagnosis and treatment of critically ill patients with BSIs. The digital droplet PCR (ddPCR) method is a potentially more powerful tool in the diagnosis of BSIs compared to other molecular methods due to its greater sensitivity, specificity, accuracy, and reproducibility. In this study, a duplex ddPCR assay for the detection of BCC and S. maltophilia in BSIs was developed.

In vitro activity of cefiderocol against Gram-negative pathogens isolated from people with cystic fibrosis and bronchiectasis.

OBJECTIVES: Gram-negative pathogens causing respiratory infection in people with cystic fibrosis and bronchiectasis are becoming progressively more resistant to conventional antibiotics. Although cefiderocol is licenced for the treatment of infections due to Gram-negative organisms, there are limited data on the activity of cefiderocol against pathogens associated with chronic respiratory diseases. The aim of this study was to determine the susceptibility of Gram-negative pathogens from cystic fibrosis and bronchiectasis to cefiderocol and comparator antibiotics. METHODS: Minimal inhibitory concentrations (MICs) of cefiderocol and 15 comparator antibiotics were determined by broth microdilution against 300 respiratory isolates: Burkholderia spp., Stenotrophomonas spp., Achromobacter spp., Ralstonia spp. and Pandoraea spp., and used to calculate the MIC of each antibiotic required to inhibit 50% (MIC50) and 90% (MIC90) of isolates. RESULTS: The MIC50 and MIC90 of cefiderocol for all 300 isolates tested was 0.25 and 32 mg/L, with 232 (77.3%) isolates having an MIC value ≤2 mg/L. In addition, cefiderocol demonstrated excellent activity against Stenotrophomonas spp. and Achromobacter spp. isolates, with 86.7% and 87.2%, respectively, exhibiting an MIC of 2 mg/L. Tigecycline also demonstrated good activity against all isolates with an MIC50 of <0.5 mg/L. CONCLUSIONS: These in vitro data demonstrated that cefiderocol had greater activity than most comparator antibiotics and could be an alternative treatment option for respiratory infection caused by these pathogens that has not responded to first-line therapy.

Phylogenomic, structural, and cell biological analyses reveal that Stenotrophomonas maltophilia replicates in acidified Rab7A-positive vacuoles of Acanthamoeba castellanii.

Acanthamoeba species are clinically relevant free-living amoebae (FLA) ubiquitously found in soil and water bodies. Metabolically active trophozoites graze on diverse microbes via phagocytosis. However, functional studies on Rab GTPases (Rabs), which are critical for controlling vesicle trafficking and maturation, are scarce for this FLA. This knowledge gap can be partly explained by the limited genetic tools available for Acanthamoeba cell biology. Here, we developed plasmids to generate fusions of A. castellanii strain Neff proteins to the N- or C-termini of mEGFP and mCherry2. Phylogenomic and structural analyses of the 11 Neff Rab7 paralogs found in the RefSeq assembly revealed that eight of them had non-canonical sequences. After correcting the gene annotation for the Rab7A ortholog, we generated a line stably expressing an mEGFP-Rab7A fusion, demonstrating its correct localization to acidified macropinocytic and phagocytic vacuoles using fluorescence microscopy live cell imaging (LCI). Direct labeling of live Stenotrophomonas maltophilia ESTM1D_MKCAZ16_6a (Sm18) cells with pHrodo Red, a pH-sensitive dye, demonstrated that they reside within acidified, Rab7A-positive vacuoles. We constructed new mini-Tn7 delivery plasmids and tagged Sm18 with constitutively expressed mScarlet-I. Co-culture experiments of Neff trophozoites with Sm18::mTn7TC1_Pc_mScarlet-I, coupled with LCI and microplate reader assays, demonstrated that Sm18 underwent multiple replication rounds before reaching the extracellular medium via non-lytic exocytosis. We conclude that S. maltophilia belongs to the class of bacteria that can use amoeba as an intracellular replication niche within a Stenotrophomonas-containing vacuole that interacts extensively with the endocytic pathway.IMPORTANCEDiverse Acanthamoeba lineages (genotypes) are of increasing clinical concern, mainly causing amoebic keratitis and granulomatous amebic encephalitis among other infections. S. maltophilia ranks among the top 10 most prevalent multidrug-resistant opportunistic nosocomial pathogens and is a recurrent member of the microbiome hosted by Acanthamoeba and other free-living amoebae. However, little is known about the molecular strategies deployed by Stenotrophomonas for an intracellular lifestyle in amoebae and other professional phagocytes such as macrophages, which allow the bacterium to evade the immune system and the action of antibiotics. Our plasmids and easy-to-use microtiter plate co-culture assays should facilitate investigations into the cellular microbiology of Acanthamoeba interactions with Stenotrophomonas and other opportunistic pathogens, which may ultimately lead to the discovery of new molecular targets and antimicrobial therapies to combat difficult-to-treat infections caused by these ubiquitous microbes.

Triple Gram-negative bacterial endophthalmitis following intravitreal injection.

PURPOSE: To describe a puzzling case of endophthalmitis caused by three unusual bacteria after intravitreal injection, its outcome, and underlying questions. FINDINGS: A 70-year-old female patient was diagnosed with acute endophthalmitis following intravitreal aflibercept injection for age-related macular degeneration. A standard tap and inject procedure was performed. Microbiological analyses on the anterior chamber and vitreous samples yielded the presence of three non-fermenting Gram-negative rods: Pseudomonas stutzeri, Stenotrophomonas maltophilia, and Ochrobactrum anthropi. The outcome was favorable after intravitreal injections of vancomycin and ceftazidime, with an almost complete recovery of the visual acuity to its baseline level. No potential source of infection was identified. CONCLUSION: Endophthalmitis following intravitreal injection can be caused by a wide variety of bacteria, including some rare Gram-negative species. They can sometimes co-exist in a single patient, but their virulence may vary greatly. Due to the variable antibiotic susceptibility and frequent multiresistance associated with non-fermenting Gram-negative rods, a prompt microbiological approach is required. Favorable outcome can be achieved with standard management.

Ventilation Management in a Patient with Ventilation-Perfusion Mismatch in the Early Phase of Lung Injury and during the Recovery.

Chest trauma is one of the most serious and difficult injuries, with various complications that can lead to ventilation-perfusion (V/Q) mismatch and systemic hypoxia. We are presenting a case of a 53-year-old male with no chronic therapy who was admitted to the Intensive Care Unit due to severe respiratory failure after chest trauma. He developed a right-sided pneumothorax, and then a thoracic drain was placed. On admission, the patient was hemodynamically unstable and tachypneic. He was intubated and mechanically ventilated, febrile (38.9 °C) and unconscious. A lung CT showed massive non-ventilated areas, predominantly in the right lung, guiding repeated therapeutic and diagnostic bronchoalveolar lavages. He was ventilated with PEEP of 10 cmH2O with a FiO2 of 0.6-0.8. Empirical broad-spectrum antimicrobial therapy was immediately initiated. Both high FiO2 and moderate PEEP were maintained and adjusted according to the current blood gas values and oxygen saturation. He was weaned from mechanical ventilation, and non-invasive oxygenation was continued. After Stenotrophomonas maltophilia was identified and treated with sulfamethoxazole/trimethoprim, a regression of lung infiltrates was observed. In conclusion, both ventilatory and antibiotic therapy were needed to improve the oxygenation and outcome of the patient with S. maltophilia pneumonia and V/Q mismatch.

Stenotrophomonas maltophilia skin infection in an immunocompetent patient: Primary cutaneous CD30+ T-cell lymphoproliferative disorder or pseudolymphoma?

Cutaneous pseudolymphomas are a wide group of diseases mimicking cutaneous lymphoma. They comprise several skin conditions with different etiopathogenesis, clinical-pathological features, and prognosis, which may occur in the absence of an identifiable trigger factor or after administration of medications or vaccinations, tattoos, infections, or arthropod bites. They present with different manifestations: from solitary to regionally clustered lesions, up to generalized distribution and, in rare cases, erythroderma. They persist variably, from weeks to years, and resolve spontaneously or after antibiotics, but may recur in some cases. CD30+ T-cell pseudolymphomas are characterized by the presence of large, activated lymphoid cells, generally in response to viral infections, arthropod assault reactions, and drug eruptions. Stenotrophomonas maltophilia is a ubiquitous Gram-negative bacillus responsible for opportunistic infections in immunocompromised patients. Infection of intact skin in immunocompetent patients is particularly rare. Here, we report a case of a man presenting an isolated nodule histopathologically mimicking a primary cutaneous CD30+ T-cell lymphoproliferative disorder.