Clinical epidemiology of Stenotrophomonas maltophilia colonization and infection: a multicenter study

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.

Prevalence and Risk Factors of Healthcare-Associated Infections among Hospitalized Pediatric Patients: Point Prevalence Survey in Thailand 2021

BACKGROUND

Healthcare-associated infections (HAIs) pose a grave threat to patient safety, morbidity, and mortality, contributing to antimicrobial resistance. Thus, we estimated the point prevalence, risk factors, types, and pathogens of HAIs in hospitalized pediatric patients.

METHODS

A point prevalence survey (PPS) of HAIs in hospitalized pediatric patients < 18 years old was conducted from March to May 2021. Outcomes, risk factors, and types of HAIs associated with HAIs in 41 hospitals across Thailand were collected.

RESULTS

The prevalence of HAIs was 3.9% (95% CI 2.9-5.0%) (56/1443). By ages < 1 month, 1 month-2 years, 2-12 years, and 12-18 years, the prevalence of HAIs was 4.2%, 3.3%, 4.1%, and 3.0%, respectively (p = 0.80). Significant independent risk factors were extended hospital length of stay (LOS) and central venous catheter (CVC) use. Compared to an LOS of <4 days, LOSs of 4-7 days, 8-14 days, and >14 days had adjusted odds ratios (aORs) of 2.65 (95% CI 1.05, 6.68), 5.19 (95% CI 2.00, 13.4), and 9.03 (95% CI 3.97, 20.5), respectively. The use of a CVC had an aOR of 2.45 (95% CI 1.06-5.66). Lower respiratory tract infection (LRTI) was the most common HAI type (46.4%: 26/56). The highest prevalence of HAIs was predominantly observed in LRTI diagnoses, with the highest among these in the <1 month age category at 2.3% (17/738).

CONCLUSION

The prevalence of HAIs in hospitalized pediatric patients was 3.9%. Extended LOS and use of CVC were HAI risk factors. A strategy for reducing LOS and reviewing insertion indications or the early planned removal of a CVC was implemented. The surveillance of HAIs stands as a cornerstone and fundamental component of IPC, offering invaluable insights that enhance hospital IPC interventions aimed at preventing HAIs.

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.

Emerging importance of multidrug-resistant Stenotrophomonas maltophilia infections in neonatal intensive care unit in a tertiary center in Turkey

OBJECTIVE

Stenotrophomonas maltophilia is an emerging multi-drug resistant, opportunistic pathogen in the neonatal intensive care unit (NICU). In this study, we aimed to assess the incidence, clinical features, antibiotic susceptibility, and treatment options of S. maltophilia infection among the healthcare-associated infections (HAIs) in the neonatal unit.

METHODS

In this study, the patients who were hospitalized in the NICU between January 2020 and December 2021 with S. maltophilia isolated from clinical samples were included. Demographic, clinic features, and microbiological findings of the patients were retrospectively evaluated by using the medical records. The samples (lower respiratory tract, urine, peritoneal fluid) were first examined microscopically by gram preparation and cultured. Antibiotic susceptibility tests were performed according to the recommendations of The European Committee on Antimicrobial Susceptibility Testing (EUCAST) for TMP-SMX.

RESULTS

S. maltophilia was isolated in 38 clinical samples of the 20 patients who were hospitalized at the NICU between January 2020 and December 2021. A total of 40 % (n = 8) of samples from different patients were accepted as colonization. Ventilator-associated pneumonia was determined in 55 % (n = 11), and urinary tract infection in 5 % (n = 1). S. maltophilia-associated bacteremia was not detected in any of the cases. The TMP-SMX susceptibilities of the strains were as it follows: 3 (15 %) were resistant (R), 7 (28 %) were susceptible (S), and 10 (47 %) were susceptible-increased exposure (I). Three of these patients were given dual antibiotics therapy (levofloxacin plus TMP-SMX) and nine of them were given only TMP-SMX. The most common hospital-acquired infectious agents are Gram negative microorganisms (51 %), followed by coagulase negative staphylococci (CNS), Staphylococcus aureus (24 %) and S. maltophilia (24 %).

CONCLUSION

Increasing TMP-SMX resistance and specific drug and dosage-related problems in the neonatal unit are important problems in treatment management.

Intra-Abdominal Abscess and Bacteremia Due to Stenotrophomonas maltophilia After Total Gastrectomy: A Case Report and Literature Review

Stenotrophomonas maltophilia (S. maltophilia) is increasingly recognized as a pathogen responsible for nosocomial infections, particularly in immunocompromised patients. The most common types of S. maltophilia infections are pneumonia and catheter-related bloodstream infection, and clinical cases of intra-abdominal abscesses due to S. maltophilia are rare. We present a rare case of intra-abdominal abscess and bacteremia as a surgical site infection (SSI) caused by S. maltophilia in a patient following total gastrectomy. We also reviewed previous literature to elucidate the clinical characteristics of intra-abdominal abscess due to S. maltophilia. The patient, a 75-year-old man with diabetes and polymyositis (treated with prednisolone), developed a fever 17 days after undergoing a total gastrectomy for gastric cancer. Abdominal computed tomography revealed a hypodense solid mass at the esophagojejunostomy site, which appeared to be an intra-abdominal abscess. The culture of both blood and drained abscess pus confirmed only S. maltophilia. Treatment with intravenous trimethoprim-sulfamethoxazole and abscess drainage led to complete resolution. The patient recovered and was discharged and did not experience a recurrence. We reviewed the English literature and found only two additional case reports of intra-abdominal abscesses caused by S. maltophilia. As in our case, the intra-abdominal abscess occurred after abdominal surgery and the source was suspected to be deep SSI. This case highlights the importance of considering S. maltophilia as a potential pathogen in patients with atypical post-surgical abdominal infections. Physicians should be aware that S. maltophilia has the potential to cause intra-abdominal abscesses secondary to SSI, in addition to Enterobacteriaceae, a major causative pathogen of SSI. Further studies are required to elucidate the etiology, epidemiology, and risk factors for SSI caused by S. maltophilia.

Global prevalence and distribution of antibiotic resistance among clinical isolates of Stenotrophomonas maltophilia: A systematic review and meta-analysis

OBJECTIVES

Stenotrophomonas maltophilia (S. maltophilia), an opportunistic pathogen, causes infection in patients undergoing immunosuppressive therapy, mechanical ventilation, or catheters and in long-term hospitalized patients. Due to its extensive resistance to various antibiotics and chemotherapeutic agents, S. maltophilia is challenging to treat. Using case reports, case series, and prevalence studies, the current study provides a systematic review and meta-analysis of antibiotic resistance profiles across clinical isolates of S. maltophilia.

METHODS

A systematic literature search was performed for original research articles published in Medline, Web of Science, and Embase databases from 2000 to 2022. Statistical analysis was performed using STATA 14 software to report antibiotic resistance of S. maltophilia clinical isolates worldwide.

RESULTS

223 studies (39 case reports/case series and 184 prevalence studies) were collected for analysis. A meta-analysis of prevalence studies demonstrated that the most antibiotic resistance worldwide was to levofloxacin, trimethoprim-sulfamethoxazole (TMP/SMX), and minocycline (14.4%, 9.2%, and 1.4%, respectively). Resistance to TMP/SMX (36.84%), levofloxacin (19.29%), and minocycline (1.75%) were the most prevalent antibiotic resistance types found in evaluated case reports/case series studies. The highest resistance rate to TMP/SMX was reported in Asia (19.29%), Europe (10.52%), and America (7.01%), respectively.

CONCLUSION

Considering the high resistance to TMP/SMX, more attention should be paid to patients' drug regimens to prevent the emergence of multidrug-resistant S. maltophilia isolates.

Upraising Stenotrophomonas maltophilia in Critically Ill Patients: A New Enemy?

Stenotrophomonas maltophilia (S. maltophilia), an important pathogen in immuno-compromised patients, has recently gained attention in patients admitted in intensive care units (ICU). We sought to investigate clinical features of infections caused by S. maltophilia in ICU patients and identify risk factors for mortality. We conducted a retrospective study in two multivalent non-COVID-19 ICUs of tertiary-teaching hospitals in Greece and Spain, including patients with isolated S. maltophilia from at least one clinical specimen along with clinical signs of infection. A total of 103 patients (66% male) were analyzed. Median age was 65.5 (54–73.3) years and mean APACHE II and SOFA scores upon ICU admission were 18.36 (±7.22) and 18.17 (±6.95), respectively. Pneumonia was the predominant clinical syndrome (72.8%), while 22% of cases were among hemato/oncology patients. Crude 28-day mortality rate was 54.8%, even though, 14-day clinical and microbiological response was 96%. Age, APACHE II on ICU admission, hemato-oncologic disease, and multi-organ failure were initially identified as potential predictors of mortality. In the multivariable analysis, only increasing age and hemato-oncologic disease were shown to be independent risk factors for 28-day mortality. High all-cause mortality was observed in critically ill patients with predominantly respiratory infections by S. maltophilia, despite initial clinical and laboratory response after targeted treatment. The study elucidates a potentially worrisome emerging pathogen in the ICU.

Stenotrophomonas maltophilia pneumonia in critical COVID-19 patients

Stenotrophomonas maltophilia, an environmental aerobic non-fermentative Gram-negative bacilli, has gained attention in many nosocomial outbreaks. COVID-19 patients in intensive care unit have extended hospital stay and are severely immunosuppressed. This study aimed to determine the prevalence and risk factors of S. maltophilia pneumonia in critical COVID-19 patients. A total of 123 COVID-19 patients in ICU admitted between March 2020 and March 2021 were identified from the authors' institutional database and assessed for nosocomial pneumonia. Demographic data and factors predisposing to S. maltophilia pneumonia were collected and analyzed. The mean age was 66 ± 13 years and 74% were males. Median APACHE and SOFA scores were 13 (IQR = 8-19) and 4 (3-6), respectively. The Median NEWS2 score was 6 (Q1 = 5; Q3 = 8). The Median ICU stay was 12 (Q1 = 7; Q3 = 22) days. S. maltophilia was found in 16.3% of pneumonia patients, leading to a lengthier hospital stay (34 vs. 20 days; p < 0.001). Risk factors for S. maltophilia pneumonia included previous treatment with meropenem (p < 0.01), thrombopenia (p = 0.034), endotracheal intubation (p < 0.001), foley catheter (p = 0.009) and central venous catheter insertion (p = 0.016). S. maltophilia nosocomial pneumonia is frequent in critical COVID-19 patients. Many significant risk factors should be addressed to reduce its prevalence and negative impact on outcomes.

Clinical challenges treating Stenotrophomonas maltophilia infections: an update

Stenotrophomonas maltophilia is a non-fermenting, Gram-negative bacillus that has emerged as an opportunistic nosocomial pathogen. Its intrinsic multidrug resistance makes treating infections caused by S. maltophilia a great clinical challenge. Clinical management is further complicated by its molecular heterogeneity that is reflected in the uneven distribution of antibiotic resistance and virulence determinants among different strains, the shortcomings of available antimicrobial susceptibility tests and the lack of standardized breakpoints for the handful of antibiotics with in vitro activity against this microorganism. Herein, we provide an update on the most recent literature concerning these issues, emphasizing the impact they have on clinical management of S. maltophilia infections.

Clinical Characteristics, Outcomes, and Risk Factors for Mortality in Patients with Stenotrophomonas maltophilia Bacteremia

This study aimed to establish the clinical features, outcomes, and factors associated with mortality in patients with Stenotrophomonas maltophilia (S. maltophilia) septicemia. The characteristics and outcome data used in this retrospective study were collected from medical records at Songklanagarind Hospital. Risk factors for survival were analyzed using χ2-tests, Kaplan−Meier curves, and Cox regression. A total of 117 patients with S. maltophilia bacteremia were analyzed. The patients’ median age was 45 years, 77 (70%) were male, 105 (90%) had comorbidities, 112 (96%) had previously undergone carbapenem therapy, and over half of the patients were on invasive medical devices. Trimethoprim-sulfamethoxazole (TMP-SMX) and fluoroquinolone showed high susceptibility rates to S. maltophilia, with 93% and 88% susceptibility, respectively. Patients who received appropriate empirical antibiotic treatment had significantly reduced 14-day, 30-day, and in-hospital mortality rates than those who did not (p < 0.001). The days of hospital stay and costs for those who received appropriate and inappropriate empirical antimicrobial treatment were 21 and 34 days (p < 0.001) and 142,463 and 185,663 baht, respectively (p < 0.002). Our results suggest that an appropriate empirical antibiotic(s) is significantly associated with lower 30-day mortality in hospitalized patients with S. maltophilia septicemia.

Clinical and Epidemiological Characteristics of Stenotrophomonas maltophilia Associated Lower Respiratory Tract Infections in Qatar: A Retrospective Study

Background

Stenotrophomonas maltophilia is a rapidly emerging nosocomial pathogen with intrinsic or acquired resistance mechanisms to several antibiotic classes. It can cause life-threatening opportunistic pneumonia, particularly among hospitalized patients. Incidence of infections by S. maltophilia has been reported as 0.07-0.4% of hospital discharges, but its mortality is 20 -60%. This is the first study from Qatar indexing the clinical and epidemiological characteristics and antibiotic susceptibility of S. maltophilia.

Materials and methods

This retrospective descriptive epidemiological study was conducted in 6 tertiary care hospitals under Hamad Medical Corporation in Doha, Qatar, analyzing inpatient respiratory isolates of S. maltophilia during 2016-17. Out-patients, children below 14 years, and non-respiratory samples except blood cultures in patients with pneumonia were excluded. Clinical records were reviewed to identify possible risk factors. Infection and colonization were identified using the Centers for Disease Control and Prevention (CDC) algorithm for clinically defined pneumonia and statistically analyzed using the chi-square test and Pearson's correlation.

Results

S. maltophilia was isolated from 2.07% (317/15312) of all respiratory samples received in the microbiology lab during our study period. Three hundred seventeen patients studied had a mean age of 60 ± 20 years, and 68% were men. Most of the isolates were from sputum (179), followed by tracheal aspirate (82) and bronchoscopy (42). Fourteen blood culture samples from patients diagnosed with pneumonia were also included. 67% were hospitalized for more than two weeks, 39.1% were on mechanical ventilators, and 88% had received a broad-spectrum antibiotic before the event. 29.1% were deemed to have an infection and 70.9% colonization. Incidence of infection in those with Charlson’s Co-morbidity Index (CCI) ≥ 3 was 36.5% compared to 24.2% in those with CCI < 3 (Relative Risk (RR)=1.52; 95% CI: 1.04,2.18; p=0.01). Patients with recent chemotherapy, immunosuppressant, or steroid use had a significantly higher infection risk than those without (69.2% v/s 23.3% RR=2.96; 95% CI:2.2,3.9; p<0.005). The most common symptoms in patients with infection were fever (96%) and expectoration (61.9%). The most common radiological finding was lobar consolidation (71.6%). Mean CRP and procalcitonin were 106.5±15.5 mg/l and 12.3 ± 14 ng/ml. Overall mortality was 16.3%. Patients on mechanical ventilator with IBMP-10 score ≥ 2 had 22.8% mortality compared to 5.7% in those with score < 2 (RR=3.9;95%CI:0.9,16.6; p<0.015). As per The US Clinical and Laboratory Standards Institute (CSLI) breakpoint values, Trimethoprim-Sulfamethoxazole (TMP-SMX) showed the highest sensitivity (97.8%), followed by levofloxacin (71.6%). 0.3% of samples were pan-drug resistant.

Conclusions

S. maltophilia is a frequent nosocomial colonizer, but it can cause nosocomial pneumonia in almost one-third of cases, specifically in immunocompromised and patients with CCI ≥ 3 with a high risk of mortality due to ventilator-associated pneumonia (VAP) in those with IBMP-10 ≥ 2. Prolonged hospital stay is a risk factor for colonization by S. maltophilia, while recent chemotherapy, immunosuppressant, or steroid use are risk factors for hospital-acquired pneumonia due to S. maltophilia. TMP-SMX and levofloxacin are the only reliable agents for monotherapy of respiratory infections due to S. maltophilia in Qatar.

Stenotrophomonas maltophilia Infections in Pediatric Patients - Experience at a European Center for Pediatric Hematology and Oncology

Stenotrophomonas maltophilia is an important nosocomial pathogen in immunocom-promised individuals and characterized by intrinsic resistance to broad-spectrum antibacterial agents. Limited data exists on its clinical relevance in immunocompromised pediatric patients, particularly those with hematological or oncological disorders. In a retrospective single center cohort study in pediatric patients receiving care at a large european pediatric hematology and oncology department, ten cases of invasive S.maltophilia infections (blood stream infections (BSI), 4; BSI and pneumonia, 3, or soft tissue infection, 2; and pneumonia, 1) were identified between 2010 and 2020. Seven patients had lymphoblastic leukemia and/or were post allogeneic hematopoietic cell transplantation. Invasive S.maltophilia infections occurred in a setting of indwelling central venous catheters, granulocytopenia, defective mucocutaneous barriers, treatment with broad-spectrum antibacterial agents, and admission to the intensive care unit. Whole genome sequencing based typing revealed no genetic relationship among four individual S.maltophilia isolates. The case fatality rate and mortality at 100 days post diagnosis were 40 and 50%, respectively, and three patients died from pulmonary hemorrhage. Invasive S.maltophilia infections are an emerging cause of infectious morbidity in patients receiving care at departments of pediatric hematology and oncology and carry a high case fatality rate.

Significance of Stenotrophomonas maltophilia When Detected in Sputum of Ambulatory Patients with COPD

Introduction

Stenotrophomonas maltophilia is an emerging Gram-negative MDR bacteria. In patients with chronic obstructive pulmonary disease (COPD), it is mostly found in those with severe exacerbation of COPD requiring mechanical ventilation. The significance of S. maltophilia when detected in the sputum of ambulatory patients with COPD is uncertain.

Objective

To access the prevalence and the risk factors of the presence of S. maltophilia in the sputum of ambulatory patients with COPD and to determine whether it was associated with prognosis.

Methods

All consecutive unselected ambulatory patients with GOLD 2–4 COPD were recruited between January 2017 and September 2019 from the COPD clinic of a tertiary care hospital. Presence of S. maltophilia was defined by a positive sputum culture for S. maltophilia. Demographics, COPD characteristics, comorbidities and known predisposing risk factors associated with S. maltophilia were collected from medical records.

Results

S. maltophilia was detected in the sputum of 41/393 (10%) of study participants. Comorbidities, exacerbation, use of oral steroids and carbapenems in the previous year were risk factors for the presence of S. maltophilia. After adjusting on confounding factors associated with mortality including age, Charlson comorbidity index and FEV₁, S. maltophilia was significantly associated with mortality (adjusted hazard ratio 2.3; 95% CI 1.1–4.9).

Conclusion

In the current study, we found that 10% of ambulatory patients with GOLD 2–4 COPD had S. maltophilia detected in their sputum. In addition, S. maltophilia may represent a marker of overall morbidity in patients with COPD.

Treatment refractory Stenotrophomonas maltophilia bacteraemia and pneumonia in a COVID-19-positive patient

Stenotrophomonas maltophilia is an opportunistic pathogen that most often infects patients requiring mechanical ventilation, indwelling central venous catheters and broad-spectrum antibiotics. The reported incidence of S. maltophilia infection has increased over the past two decades, and many of its risk factors are commonly seen in patients with severe COVID-19 infection. Our case regards a patient with severe COVID-19 pneumonia, who subsequently developed disseminated S. maltophilia infection, refractory to first-line treatment and optimal medical management. This case highlights the high index of suspicion required for diagnosing secondary complications in patients with COVID-19 infection and highlights the difficulty in treating disseminated S. maltophilia infection in critically ill patients.

Stenotrophomonas maltophilia: An uncommon cause of liver abscess

We report an uncommon case of pyogenic liver abscess due to Stenotrophomonas maltophilia in an apparently immune-competent individual, the timely recognition of which could avoid a potentially fatal course of infection in the patient. A 45-year-old man, with history of moderate alcohol intake since the last 10 years, was admitted with intense right-sided upper abdominal pain and right-sided chest pain of 10-days duration. Culture of the ultrasound-guided liver aspirate sample yielded a pure growth of S. maltophilia identified by the VITEK-2™ automated microbial identification system. Treatment with parenteral levofloxacin and oral trimethoprim-sulfamethoxazole along with pigtail catheter drainage and other appropriate supportive management led to resolution of the abscess with no recurrence of infection at two months follow-up. Physicians need to be aware that S. maltophilia infections may not be restricted to hospitalized patients as a low-virulence opportunistic pathogen, but may occur as an important emerging pathogen in community-acquired infections as well.

Stenotrophomonas maltophilia, an emerging pathogen in newborns: Three case reports and a review of the literature

BACKGROUND

Stenotrophomonas maltophilia (S. maltophilia) is a rare cause of neonatal sepsis with significant morbidity and mortality and has extensive resistance to several antibiotics leaving few options for antimicrobial therapy. Only a few cases have been reported in neonates from developing countries. We report three cases of critically ill, extramural babies with neonatal S. maltophilia sepsis. All three babies recovered and were discharged.

CASE SUMMARY

All three cases were term extramural babies, who were critically ill at the time of presentation at our neonatal intensive care unit. They had features of multiorgan dysfunction at admission. Blood culture was positive for S. maltophilia in two babies and one had a positive tracheal aspirate culture. The babies were treated according to the antibiogram available. They recovered and were subsequently discharged.

CONCLUSION

Although various authors have reported S. maltophilia in pediatric and adult populations, only a few cases have been reported in the newborn period and this infection is even rarer in developing countries. Although S. maltophilia infection has a grave outcome, our three babies were successfully treated and subsequently discharged.

Risk Factors of Stenotrophomonas maltophilia Blood Stream Infections: Comparison With Other Gram-Negative Blood Stream Infections in Children

BACKGROUND

Stenotrophomonas maltophilia, is a nonfermentative, aerobic, Gram-negative bacilli which is intrinsically resistance to several antibiotics. Treatment options for this bacteria are quite different from the other Gram-negative bacilli, which can represent a therapeutic challenge. To initiate appropriate empiric treatment and to reduce mortality, differentiation of S. maltophilia from other Gram-negative bacteria is critically important. The aim of this study is to distinguish the risk factors of S. maltophilia blood stream infections (BSI) from other Gram-negative BSI.

METHODS

This was a retrospective, case-control study. Patients with S. maltophilia BSI were selected as cases and patients with non-S. maltophilia Gram-negative BSI were selected as controls. Demographic and clinical characteristics of patients were recorded.

RESULTS

Forty-eight cases with S. maltophilia BSI and 144 controls were enrolled in the study. Risk factors for S. maltophilia BSI compared with the control group includes prior use of antibiotics, especially carbapenem, pediatric intensive care unit stay, mechanical ventilator use, indwelling catheters and duration of hospitalization.

CONCLUSIONS

Breakthrough infection by S. maltophilia can occur in severely ill patients being treated with carbapenem. In the presence of risk factors, to reduce morbidity and mortality, S. maltophilia should be kept in mind when starting empiric treatment.

Stenotrophomonas maltophilia Infection in a Patient with Acute Exacerbation of Chronic Obstructive Pulmonary Disease (COPD): A Colonizer or True Infection?

BACKGROUND This article describes a finding of sputum culture positive for Stenotrophomonas maltophilia in an elderly woman with past medical history of chronic obstructive pulmonary disease (COPD) and hypertension, presenting with acute hypoxemic hypercapnic respiratory failure secondary to COPD exacerbation from bronchitis/bronchopneumonia. CASE REPORT Computed tomography (CT) of the chest showed secretions in the lower lobe bronchi and small scattered clustered nodules consistent with bronchitis/mild bronchopneumonia without evidence of pulmonary embolism. A sputum culture was positive for Stenotrophomonas maltophilia. She was treated with trimethoprim/sulfamethoxazole for 10 days. She recovered and was subsequently discharged from the hospital. CONCLUSIONS Stenotrophomonas maltophilia, previously known as a colonizer, is now being recognized as a true respiratory infection, especially in immunocompromised patients and those with chronic diseases like COPD presenting with signs and symptoms of infection. Therefore, early identification and prompt treatment of Stenotrophomonas maltophilia infection is important for a favorable outcome.

Stenotrophomonas maltophilia Infections: Clinical Characteristics and Factors Associated with Mortality of Hospitalized Patients

Purpose

To study the clinical characteristics and factors associated with mortality of patients who had Stenotrophomonas maltophilia infections.

Patients and Methods

We conducted a retrospective study to determine the clinical characteristics and factors associated with mortality for S. maltophilia infections among hospitalized adult patients at Siriraj Hospital. The clinical and microbiological data were collected from medical records December 2013–December 2016.

Results

Of 1221 subjects whose clinical samples grew S. maltophilia, 213 were randomly selected for chart review. One hundred patients with a true infection were analyzed. Their median age was 66 years; 47 were males; 46 were critically ill with a median APACHE II score of 18 (2–32); and 91 received antibiotic treatment, mainly with carbapenems (56%), before being diagnosed with a S. maltophilia infection. Pulmonary (53%) and bloodstream infections (25%) were the most common infections. The median length of hospitalization was 19 days before infection onset. The in-hospital mortality rate was 54%. The following factors were associated with mortality: a pre-existing respiratory infection (OR 6.28, 1.33–29.78; p.021); critical illness (OR 3.33, 1.45–7.62; p.005); multi-organ dysfunction (OR 2.44, 1.05–5.70; p.039); being on mechanical ventilation (OR 4.44, 1.90–10.39; p.001); concurrent immunosuppressive therapy (OR 2.67, 1.10–6.47; p.029); intravascular (OR 4.43, 1.79–10.92; p.001) and urinary catheterization (OR 4.83, 1.87–12.47; p.001); and serum albumin <3 g/dL (OR 4.13, 1.05–16.33; p.043). A multivariate analysis identified two independent factors associated with mortality: being on mechanical ventilation (OR 4.43, 1.86–10.59; p 0.001) and receiving concurrent immunosuppressive therapy (OR 2.26, 1.04–6.82; p 0.042).

Conclusion

S. maltophilia can cause nosocomial infections with high mortality, particularly in patients with a prolonged hospitalization. Concurrent immunosuppressive therapy and being on mechanical ventilation are the independent factors associated with a fatal outcome.

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

Stenotrophomonas maltophilia is an aerobic, oxidase-negative and catalase-positive bacillus. S. maltophilia is a recognized opportunistic pathogen. Due to the advancements in invasive medical procedures, organ transplantation and chemotherapy of malignant illnesses, the relevance of this pathogen increased significantly. The therapy of S. maltophilia infections is challenging, as these bacteria show intrinsic resistance to multiple classes of antibiotics, the first-choice drug is sulfamethoxazole/trimethoprim. Our aim was to assess the epidemiology of S. maltophilia from various clinical samples and the characterization of resistance-levels and resistotyping of these samples over a long surveillance period. The study included S. maltophilia bacterial isolates from blood culture samples, respiratory samples and urine samples and the data for the samples, received between January 2008 until December 2017, a total of 817 S. maltophilia isolates were identified (respiratory samples n = 579, 70.9%, blood culture samples n = 175, 21.4% and urine samples n = 63, 7.7%). Levofloxacin and colistin-susceptibility rates were the highest (92.2%; n = 753), followed by tigecycline (90.5%, n = 739), the first-line agent sulfamethoxazole/trimethoprim (87.4%, n = 714), while phenotypic resistance rate was highest for amikacin (72.5% of isolates were resistant, n = 592). The clinical problem of sulfamethoxazole/trimethoprim-resistance is a complex issue, because there is no guideline available for the therapy of these infections.

Resistance Levels and Epidemiology of Non-Fermenting Gram-Negative Bacteria in Urinary Tract Infections of Inpatients and Outpatients (RENFUTI): A 10-Year Epidemiological Snapshot

Background: Urinary tract infections (UTIs) are one of the most common infections in the human medicine, both among outpatients and inpatients. There is an increasing appreciation for the pathogenic role of non-fermenting Gram-negative bacteria (NFGNBs) in UTIs, particularly in the presence of underlying illnesses. Methods: The study was carried out using data regarding a 10-year period (2008-2017). The antimicrobial susceptibility testing was performed using the disk diffusion method, E-tests, and broth microdilution. Results: NFGNB represented 3.46% ± 0.93% for the outpatients, while 6.43% ± 0.81% of all positive urine samples for the inpatients (p < 0.001). In both groups, Pseudomonas spp. (78.7% compared to 85.1%) and Acinetobacter spp. (19.6% compared to 10.9%), were the most prevalent. The Acinetobacter resistance levels were significantly higher in inpatients isolates (p values ranging between 0.046 and <0.001), while the differences in the resistance levels of Pseudomonas was not as pronounced. The β-lactam-resistance levels were between 15-25% and 12-28% for the Acinetobacter and Pseudomonas spp., respectively. 4.71% of Acinetobacter and 1.67% of Pseudomonas were extensively drug resistant (XDR); no colistin-resistant isolates were recovered. Conclusions: Increasing resistance levels of the Acinetobacter spp. from 2013 onward, but not in the case of the Pseudomonas spp. Although rare, the drug resistant NFGNB in UTIs present a concerning therapeutic challenge to clinicians with few therapeutic options left.

Prevalence and Antibiotic Resistance of Stenotrophomonas maltophilia in Respiratory Tract Samples: A 10-Year Epidemiological Snapshot

Background:

Since the 1980s, Stenotrophomonas maltophilia has emerged as an important pathogen associated with significant mortality in pneumonia and bacteremia of severely immunocompromised, hospitalized patients. The drug of choice in S maltophilia infections is sulfamethoxazole-trimethoprim (SMX/TMP); SMX/TMP resistance is a serious concern in clinical practice. The aim of this study was to assess the prevalence of S maltophilia in lower respiratory tract (LRTI) samples at a tertiary-care university hospital.

Methods:

This retrospective cohort study was carried out using microbiological data collected between January 2008 and December 2017. Routine antimicrobial susceptibility testing was performed for SMX/TMP and levofloxacin; in case of resistance, susceptibility testing for additional antibiotics (tigecycline, amikacin, and colistin) was also performed.

Results:

A total of 579 individual S maltophilia isolates were identified (2008-2012: n = 160, 2013-2017: n = 419; P = .0008). In all, 78.46% of patients were younger than 5 or older than 50 years of age and had recent trauma, surgery, or underlying conditions (malignancies, respiratory distress syndrome, congenital disorders, and cystic fibrosis). In 28.16% of samples, more than 1 pathogen was identified, and 5.35% of coisolated pathogens were multidrug resistant (MDR). In all, 12.1% of isolates were SMX/TMP-resistant (2008-2012: 6.12%, 2013-2017: 18.06%; P = .034), while 8.99% were resistant to levofloxacin (2008-2012: 7.86%, 2013-2017: 10.12%; P > .05). SMX/TMP resistance was detected more frequently in samples originating from inpatients (n = 2.50 ± 2.39 vs n = 11.50 ± 3.76; P = .0002).

Conclusions:

In all, 5.87% of isolates were extensively drug resistant (XDR), that is, in addition to SMX/TMP, they were resistant to levofloxacin, amikacin, colistin, and tigecycline. The results of our study correspond to the findings in the literature.

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

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

Stenotrophomonas maltophilia Endocarditis of an Implantable Cardioverter Defibrillator Lead

Stenotrophomonas maltophilia (S. maltophilia) is a nosocomial pathogen and a rare cause of infective endocarditis (IE). Given the intrinsic resistance to many classes of antibiotics, IE due to S. maltophilia carries significant morbidity and mortality among the cases described. Prompt identification of risk factors, particularly the use of medical devices, is necessary for the timely identification of this organism and prompt medical management. We report a case of an implantable cardioverter defibrillator (ICD) lead associated IE due to S. maltophilia and discuss the diagnosis, treatment and outcomes in relation to existing evidence.

Stenotrophomonas maltophilia: From trivial to grievous

Stenotrophomonas maltophilia, once regarded as an organism of low virulence, has evolved as a significant opportunistic pathogen causing severe human infections in both hospital and community settings, especially amongst highly debilitated patients. Globally, S. maltophilia ranks third amongst the four most common pathogenic non-fermenting Gram-negative bacilli (NFGNBs), others being Pseudomonas aeruginosa, Acinetobacter baumannii and Burkholderia cepacia complex (Bcc). The worth of accurate identification of S. maltophilia comes to the forefront as it needs to be differentiated from other NFGNBs such as Acinetobacter, P. aeruginosa and Bcc due to its inherently contrasting antibiotic susceptibility pattern. Consequently, its correct identification is essential as no single drug is amply effective against all NFGNBs, which hinders initiation of appropriate empirical treatment resulting in increased morbidity and mortality.

Medical Management of Endocarditis Caused by Stenotrophomonas maltophilia: A Case Report

A 44-year-old female was found to be systemically ill at dialysis and admitted to the hospital. Days into the hospitalization, her blood cultures from dialysis were positive with Stenotrophomonas maltophilia bacteremia with a levofloxacin minimum inhibitory concentration (MIC) of 1. She was discharged on ciprofloxacin 500 mg orally (PO) daily on hospital day 2 to complete a 14-day course. Weeks later, she was again found to be bacteremic at dialysis and sent back to the hospital. She was started on empiric antibiotics upon admission until further identification. Blood cultures again revealed S. maltophilia with a levofloxacin MIC of 32. Antibiotics were tailored to trimethoprim/sulfamethoxazole (TMP-SMX) until susceptibilities for additional agents were available. Further workup revealed mitral valve endocarditis. She was subsequently discharged on both minocycline 100 mg PO every 12 hours and TMP-SMX 1 DS PO daily with a planned duration of 6 weeks. Due to ongoing readmissions for hyperkalemia, TMP-SMX was discontinued and her regimen was modified to ceftazidime 1 g intravenously (IV) after HD plus minocycline 100 mg PO every 12 hours. She was deemed clinically and microbiologically cleared based on follow-up assessments. To our knowledge, this is the first case of S. maltophilia endocarditis treated with oral minocycline in combination with another antibiotic.

Emergence of Stenotrophomonas maltophilia nosocomial isolates in a Saudi children's hospital. Risk factors and clinical characteristics

Objectives:

To describe the clinical characteristics of pediatric patients colonized or infected by Stenotrophomonas maltophilia (S. maltophilia) at a Saudi children’s hospital, to identify risk factors associated with infection, and to investigate the antimicrobial resistance patterns of this emerging pathogen.

Methods:

In this cross-sectional observational study, 64 non-duplicating S. maltophilia strains were isolated in Najran Maternity and Children’s Hospital, Najran, Saudi Arabia between January 2015 to February 2016. Antimicrobial susceptibility testing was performed using the reference broth microdilution method.

Results:

In this study, 48 (75%) isolates were identified in true infections and 16 (25%) isolates were considered colonization. The main types of S. maltophilia infection were pneumonia in 22 (45.8%) patients and bloodstream infection in 14 (29.2%) patients. The significant risk factors included exposure to invasive procedure (p=0.02), and presence of acute leukemia as an underlying disease (p=0.02). The most active antimicrobials were trimethoprim/sulfamethoxazole (100% sensitivity) and tigecycline (93.7% sensitivity).

Conclusions:

Stenotrophomonas maltophilia is an emerging nosocomial pathogen among pediatric patients. Accurate identification and susceptibility testing of this emerging pathogen are crucial for the management of infected patients and prevention of spread of this nosocomial pathogen.

Unusual case of rapid growing intraabdominal abscess caused by Stenotrophomonas maltophilia after laparoscopic appendectomy due to perforated appendicitis: A case report

INTRODUCTION

An intraabdominal abscess due to Stenotrophomonas maltophilia (S maltophilia) infection is a very rare clinical manifestation. S maltophilia is a glucose nonfermentative, aerobic, gram-negative, mobile, and biofilm-forming bacterium. It is an opportunistic pathogen and uncommon cause of infection. Respiratory tract infections (pneumonia) and bloodstream infections (bacteremia) are the most common clinical manifestations of S maltophilia infection.

CONCLUSIONS

This case report describes an unusual case of a rapidly growing, extremely large intraabdominal abscess (within 1 week during antibiotic therapy), which was detected 2 weeks after a laparoscopic appendectomy was performed for perforated appendicitis and was caused by multidrug-resistant S maltophilia infection.

Risk factors for mortality in patients with Stenotrophomonas maltophilia bacteremia

Stenotrophomonas maltophilia is a nosocomial pathogen associated with high morbidity and mortality, particularly in immunocompromised or critically ill patients. In this study, we investigated the risk factors for mortality in patients with S. maltophilia bacteremia.Retrospectively, medical records from all patients with S. maltophilia bacteremia between December 2005 and 2014 at Severance Hospital, a 2000-bed tertiary care hospital in Seoul, Korea, were reviewed. Analysis was performed to identify factors associated with 28-day mortality.In total, 142 bacteremia patients were enrolled in this study. The overall 28-day mortality rate was 36.6%. Based on the univariate analysis, hematologic malignancy (P = 0.015), Sepsis-related Organ Failure Assessment (SOFA) score (P < 0.001) and the removal of a central venous catheter (CVC) (P = 0.040) were significantly related to mortality. In the intensive care unit patients, the Acute Physiology and Chronic Health Evaluation II score (P = 0.001) also had significance. Based on the multivariate analysis, the SOFA score (odds ratio [OR] = 1.323; 95% confidence interval [CI]: 1.159, 1.509; P < 0.001) and removal of the CVC (OR = 0.330; 95% CI: 0.109, 0.996; P = 0.049) were independent factors associated with mortality.Our results suggest that removing a CVC may considerably reduce mortality in patients with S. maltophilia bacteremia.

Characteristics of Stenotrophomonas maltophilia bacteremia in children

BACKGROUND

Empiric antimicrobial coverage in compromised hosts commonly includes pseudomonal coverage but often lacks coverage against Stenotrophomonas maltophilia. Identification of risk factors specific for S. maltophilia infection may lead to prompt initiation of appropriate antibiotics and improved outcome.

METHODS

We conducted a retrospective analysis of pediatric patients with bacteremia due to S. maltophilia or Pseudomonas aeruginosa from April 2002 to July 2014 at a tertiary children's hospital. Patient demographics, underlying disease, clinical course, and treatment were compared between S. maltophilia and P. aeruginosa cases.

RESULTS

Nineteen children with S. maltophilia bacteremia and 49 children with P. aeruginosa bacteremia were identified. On multivariate logistic regression analysis, use of carbapenems within 7 days prior to onset (OR, 5.00; 95%CI: 1.25-20.07; P = 0.02) and previous intensive care unit stay (OR, 3.75; 95%CI: 1.13-12.47; P = 0.03) were significantly associated with S. maltophilia bacteremia compared with P. aeruginosa bacteremia. The majority of the S. maltophilia bacteremia patients had central line-associated bloodstream infection (79%), compared with the P. aeruginosa bacteremia patients (37%, P = 0.002). There were nine children (47%) who had polymicrobial infection in the S. maltophilia bacteremia group, in contrast to four (8%) in the P. aeruginosa bacteremia group (OR, 10.13; 95%CI: 2.59-39.56; P = 0.001). Consultation with an infectious diseases physician was associated with a lower rate of persistent S. maltophilia bacteremia (P = 0.04).

CONCLUSIONS

Stenotrophomonas maltophilia should be considered in breakthrough bacteremia in pediatric patients who receive carbapenems within 7 days prior to onset.

Update on infections caused by Stenotrophomonas maltophilia with particular attention to resistance mechanisms and therapeutic options

Stenotrophomonas maltophilia is a Gram-negative, biofilm-forming bacterium. Although generally regarded as an organism of low virulence, S. maltophilia is an emerging multi-drug resistant opportunistic pathogen in hospital and community settings, especially among immunocompromised hosts. Risk factors associated with S. maltophilia infection include underlying malignancy, cystic fibrosis, corticosteroid or immunosuppressant therapy, the presence of an indwelling central venous catheter and exposure to broad spectrum antibiotics. In this review, we provide a synthesis of information on current global trends in S. maltophilia pathogenicity as well as updated information on the molecular mechanisms contributing to its resistance to an array of antimicrobial agents. The prevalence of S. maltophilia infection in the general population increased from 0.8-1.4% during 1997-2003 to 1.3-1.68% during 2007-2012. The most important molecular mechanisms contributing to its resistance to antibiotics include β-lactamase production, the expression of Qnr genes, and the presence of class 1 integrons and efflux pumps. Trimethoprim/sulfamethoxazole (TMP/SMX) is the antimicrobial drug of choice. Although a few studies have reported increased resistance to TMP/SMX, the majority of studies worldwide show that S. maltophilia continues to be highly susceptible. Drugs with historically good susceptibility results include ceftazidime, ticarcillin-clavulanate, and fluoroquinolones; however, a number of studies show an alarming trend in resistance to those agents. Tetracyclines such as tigecycline, minocycline, and doxycycline are also effective agents and consistently display good activity against S. maltophilia in various geographic regions and across different time periods. Combination therapies, novel agents, and aerosolized forms of antimicrobial drugs are currently being tested for their ability to treat infections caused by this multi-drug resistant organism.

Clinical Features and Epidemiology ofAcinetobacter baumanniiColonization and Infection in Spanish Hospitals

Objective:

To investigate the clinical features and the epidemiology ofAcinetobacter baumanniiin Spanish hospitals.

Design:

Prospective multicenter cohort study.

Setting:

Twenty-seven general hospitals and one paraplegic center in Spain.

Methods:

All cases ofA. baumanniicolonization or infection detected by clinical samples during November 2000 were included. Isolates were identified using phenotypic and genotypic methods. The molecular relatedness of the isolates was assessed by pulsed-field gel electrophoresis.

Results:

Twenty-five (89%) of the hospitals had 221 cases (pooled rate in general hospitals, 0.39 case per 1,000 patient-days; range, 0 to 1.17). The rate was highest in intensive care units (ICUs). Only 3 cases were pediatric. The mean age of the patients in the general hospitals was 63 years; 69% had a chronic underlying disease and 80% had previously received antimicrobial treatment. Fifty-three percent of the patients had an infection (respiratory tract, 51%; surgical site, 16%; and urinary tract, 11%). Crude mortality was higher in infected than in colonized patients (27% vs 10%; relative risk, 1.56; 95% confidence interval, 1.2 to 2.0;P= .003). Molecular analysis disclosed 79 different clones. In most hospitals, a predominant epidemic clone coexisted with other sporadic clones. Imipenem resistance was present in 39% of the hospitals.

Conclusions:

A. baumanniiwas present in most participating Spanish hospitals (particularly in ICUs) with different rates among them. The organisms mainly affected predisposed patients; half of them were only colonized. Epidemic and sporadic clones coexisted in many centers.

Stenotrophomonas maltophilia infections in a general hospital: patient characteristics, antimicrobial susceptibility, and treatment outcome

Introduction

Stenotrophomonas maltophilia is acquiring increasing importance as a nosocomial pathogen.

Methods

We retrospectively studied the characteristics and outcome of patients with any type of S. maltophilia infection at the University Hospital of Heraklion, Crete, Greece, between 1/2005–12/2010. S. maltophilia antimicrobial susceptibility was tested with the agar dilution method. Prognostic factors for all-cause in-hospital mortality were assessed with multivariate logistic regression.

Results

Sixty-eight patients (median age: 70.5 years; 64.7% males) with S. maltophilia infection, not related to cystic fibrosis, were included. The 68 patients were hospitalized in medical (29.4%), surgical (26.5%), hematology/oncology departments (23.5%), or the intensive care units (ICU; 20.6%). The most frequent infection types were respiratory tract (54.4%), bloodstream (16.2%), skin/soft tissue (10.3%), and intra-abdominal (8.8%) infection. The S. maltophilia-associated infection was polymicrobial in 33.8% of the cases. In vitro susceptibility was higher to colistin (91.2%), trimethoprim/sulfamethoxazole and netilmicin (85.3% each), and ciprofloxacin (82.4%). The empirical and the targeted treatment regimens were microbiologically appropriate for 47.3% and 63.6% of the 55 patients with data available, respectively. Most patients received targeted therapy with a combination of agents other than trimethoprim/sulfamethoxazole. The crude mortality and the mortality and the S. maltophilia infection-related mortality were 14.7% and 4.4%, respectively. ICU hospitalization was the only independent prognostic factor for mortality.

Conclusion

S. maltophilia infection in a general hospital can be associated with a good prognosis, except for the patients hospitalized in the ICU. Combination reigmens with fluoroquinolones, colistin, or tigecycline could be alternative treatment options to trimethoprim/sulfamethoxazole.

Stenotrophomonas maltophilia--the most worrisome threat among unusual non-fermentative gram-negative bacilli from hospitalized patients: a prospective multicenter study

OBJECTIVES

Isolation rates of unusual non-fermentative Gram-negative bacilli (i.e. other than Pseudomonas aeruginosa and Acinetobacter baumannii) are increasing but studies are limited to few observations. We aimed at determining risk factors for infection and influence of antibiotic treatment on the outcome.

METHODS

A six-month (December 1, 2008-May 31, 2009) prospective multicenter cohort study was conducted in nine French teaching hospitals. Characteristics of patients colonized or infected by unusual NF-GNB, adequacy of antimicrobial therapies, and outcome were analyzed.

RESULTS

Analysis of 158 patients (median age, 62.7 years) was conducted. Stenotrophomonas maltophilia was the predominant bacterial species isolated (39%) followed by Achromobacter group (15%) and non-baumannii Acinetobacter species (13%). Compared to colonized patients, infected ones were more frequently immunocompromised [relative risk (RR) = 1.63, (95% confidence interval (CI) = 1.02-2.60, P = 0.05)], hospitalized within the last three months [RR 1.67 (95% CI 1.09-2.58, P = 0.02)], admitted in an intensive care unit with central venous catheter [RR 1.74 (95% CI 1.15-2.63, P = 0.01)]. The overall hospital mortality concerned 28 patients (18%) but no association with inadequate antimicrobial treatment was found except in the group of S. maltophilia infected cases [RR 2.81 (95% CI 1.01-7.83, P = 0.02)].

CONCLUSION

Naturally carbapenems-resistant S. maltophilia is the main unusual NF-GNB pathogen in hospitalized patients, leading to inappropriate empirical antibiotic treatment at the time of emerging extended-spectrum β-lactamase-producing bacteria.

Risk factors and clinical characteristics of Stenotrophomonas maltophilia infections in neonates

BACKGROUND

The aim of this study was to review the risk factors and clinical, bacteriological, and epidemiological characteristics of Stenotrophomonas maltophilia infections in our neonatal intensive care unit.

METHODS

A retrospective matched case-control study was performed by comparing 23 cases of S maltophilia with 45 controls to identify the potential risk factors. To identify the case patients, the admission and medical records of patients in the neonatal intensive care unit and records from the Microbiology Department were reviewed between 2003 and 2008.

RESULTS

Sepsis in two neonates (9%), conjunctivitis in two neonates (9%), and ventilator-associated pneumonia in 19 (82%) neonates were determined. Invasive-procedures, exposure to aminoglycoside and carbapenem, total parenteral nutrition, histamine 2 blockers, exposure to steroids, cholestasis, and duration of hospitalization were significantly associated with S maltophilia infections (p<0.05). On multivariate analysis, invasive procedures (odds ratio, 18.81) and duration of hospitalization (odds ratio, 1.06) were determined to be the risk factors for S maltophilia infection. The most active antimicrobial agent was trimethoprim/sulfamethoxazole (87%) for S maltophilia infection, and the mortality rate was 17%.

CONCLUSIONS

Neonatologists should avoid from unnecessary invasive procedures and broad-spectrum antibiotics to reduce S maltophilia infections. Invasive procedures should be finished in the shortest time possible. Agent/factor-specific antibacterial treatment should be administered. Patients being discharged as early as possible will also reduce infection frequency. Stenotrophomonas maltophilia should be considered in patients with high Stenotrophomonas infection risk factors.

The role of Stenotrophomonas maltophilia in refractory chronic rhinosinusitis

BACKGROUND

Stenotrophomonas maltophilia is a multidrug-resistant Gram-negative bacillus that has been implicated in serious nosocomial infections. This microbe has also been isolated from sinus cultures in refractory chronic rhinosinusitis (CRS). The goal of this study was to elucidate the implications of S. maltophilia-positive cultures in the setting of CRS. The objectives of the study were (1) to define clinical and microbiological characteristics and (2) to assess management strategy and overall outcomes of S. maltophilia-positive sinus cultures in CRS patients.

METHODS

A retrospective review was performed of 101 patients over a 5-year period.

RESULTS

The mean age was 56.9 years with a female/male ratio of 1.1:1. Previous sinus surgery had been performed in 90.1% of patients. Greater than 97% of patients had been given antibiotics in the previous 6 months. The most common presenting symptom was discolored nasal drainage (76.2%) with endoscopic evidence of pus or crusting in 83.2% of cases. Monotherapy with trimethoprim sulfamethoxazole (TMX) or fluoroquinolones was used in 41 and 26%, respectively. This intervention resulted in overall symptom and endoscopic improvement in 70% of cases.

CONCLUSION

The presence of S. maltophilia isolates on culture are associated with clinically relevant symptoms and endoscopic findings in patients with refractory CRS. Despite its multidrug-resistant nature, monotherapy with TMX or fluoroquinolones appears to be effective in providing patients with bacterial infection with symptom relief in a majority of cases.

Ecthyma Gangrenosum: A Rare Cutaneous Manifestation Caused by Stenotrophomonas maltophilia in a Leukemic Patient

Ecthyma gangrenosum (EG) is a well-recognized cutaneous infection that most commonly affects immunocompromised patients. It typically occurs on the extremities, or in gluteal and perineal regions. Although Pseudomonas aeruginosa is the most well-known pathogen causing EG, other organisms have been reported to cause EG. Herein we report a rare case of ecthyma gangrenosum presenting as aggressive necrotic skin lesions in perioral and infraorbital areas in a 47-year-old patient with acute myelocytic leukemia after allogeneic bone marrow transplantation. It was caused by Stenotrophomonas maltophilia, which is an aerobic, gram-negative pathogen that has been associated only rarely with cutaneous disease. Blood culture and tissue culture were positive for S. maltophilia. Histological examination revealed numerous tiny bacilli in the dermis and perivascular area. Early recognition of skin lesions caused by S. maltophilia is important to decrease associated mortality in immunosuppressed patients.

Stenotrophomonas maltophilia: an emerging opportunist human pathogen

Stenotrophomonas maltophilia has emerged as an important opportunistic pathogen in the debilitated host. S maltophilia is not an inherently virulent pathogen, but its ability to colonise respiratory-tract epithelial cells and surfaces of medical devices makes it a ready coloniser of hospitalised patients. S maltophilia can cause blood-stream infections and pneumonia with considerable morbidity in immunosuppressed patients. Management of infection is hampered by high-level intrinsic resistance to many antibiotic classes and the increasing occurrence of acquired resistance to the first-line drug co-trimoxazole. Prevention of acquisition and infection depends upon the application of modern infection-control practices, with emphasis on the control of antibiotic use and environmental reservoirs.

Factors associated with mortality in patients with bloodstream infection and pneumonia due to Stenotrophomonas maltophilia

Severe infections caused by Stenotrophomonas maltophilia are associated with high mortality, and strategies to improve the clinical outcome for infected patients are needed. A retrospective cohort study of patients with bloodstream infection (BSIs) and pneumonia caused by S. maltophilia was conducted. Multivariate analysis was performed to access factors associated with 14-day mortality. A total of 60 infections were identified. Among these, eight (13%) were pneumonias and 52 were BSIs; 33.3% were primary, 13% were central venous catheter (CVC)-related and 40% were secondary BSIs. Fifty-seven (85%) patients had received previous antimicrobial therapy; 88% had CVC, 57% mechanical ventilation and 75% were in the intensive care unit at the onset of infection. Malignancy (45%) was the most frequent underlying disease. The mean of the Acute Physiology and Chronic Health Evaluation II (APACHE II) scores was 17 and for the Sepsis-related Organ Failure Assessment (SOFA) score, it was 7 points. The overall and 14-day mortality were, respectively, 75% and 48%. Forty-seven (78%) patients were treated and, of these, 74% received trimethoprim-sulfamethoxazole. Independent risk factors associated with mortality were SOFA index >6 points (0.005) and septic shock (0.03). The Kaplan-Meier estimations curves showed that patients with APACHE II score >20 and SOFA score >10 had a survival chance of, respectively, less than 8% and less than 10% (P<or=0.001) at 21 days after the first positive S. maltophilia culture. Our results suggest that the independent factors associated with outcome in patients with infection caused by S. maltophilia are septic shock and higher SOFA index.

Antimicrobial therapy for Stenotrophomonas maltophilia infections

Stenotrophomonas maltophilia has emerged as an important nosocomial pathogen capable of causing respiratory, bloodstream, and urinary infections. The treatment of nosocomial infections by S. maltophilia is difficult, as this pathogen shows high levels of intrinsic or acquired resistance to different antimicrobial agents, drastically reducing the antibiotic options available for treatment. Intrinsic resistance may be due to reduced outer membrane permeability or to the multidrug efflux pumps. However, specific mechanisms of resistance such as aminoglycoside-modifying enzymes or the heterogeneous production of metallo-beta-lactamase have contributed to the multidrug-resistant phenotype displayed by this pathogen. Moreover, the lack of standardized susceptibility tests and their interpretative criteria hinder the choice of an adequate antibiotic treatment. Recommendations for the treatment of infections by S. maltophilia are based on in vitro studies, certain nonrandomized clinical trials, and anecdotal experience. Trimethoprim-sulfamethoxazole remains the drug of choice, although in vitro studies indicate that ticarcillin-clavulanic acid, minocycline, some of the new fluoroquinolones, and tigecycline may be useful agents. This review describes the main resistance mechanisms, the in vitro susceptibility profile, and treatment options for S. maltophilia infections.