Multidrug-resistant Gram-negative Research Articles

279. A Decision Tree Using Clinical Characteristics to Predict a Hospitalized Child’s Risk of a Multidrug-Resistant Gram-Negative Bloodstream Infection

BackgroundAs the threat of multidrug-resistant Gram-negative (MDRGN) bacteria rises, recognizing children at high risk of bloodstream infections with bacteria resistant to commonly prescribed empiric antibiotics is critical. We developed a decision tree to predict which pediatric bloodstream infections were due to MDRGN bacteria resistant to cefepime or piperacillin–tazobactam, commonly prescribed empiric antibiotics.MethodsWe conducted a longitudinal retrospective cohort study at the Children’s Hospital of Pittsburgh including all admitted patients with a Gram-negative bloodstream infection from June 2009 to June 2015. Episodes of bloodstream infection were considered unique if at least 30 days had elapsed since the previous bloodstream infection. Logistic regression was performed to identify notable risk factors. A decision tree describing the risk of an MDRGN infection was developed using recursive partitioning based on clinical characteristics available at the time of presentation.ResultsSix hundred eighty-nine episodes of Gram-negative bloodstream infections occurred during the study period among 387 patients. Twenty-eight percent of infections were multidrug-resistant (MDR). The decision tree separated patients into higher or lower risk groups based on history of prior carbapenem treatment for seven or more days, having a prior MDR infection within 6 months, intestinal transplant status, age 3 years or older, and seven or more prior episodes of bacteremia. The sensitivity to classify high risk of MDR was 46% and the specificity was 92% based on leave one out cross validation. For patients who had more than one episode, 30% of initially non-MDR infections were subsequently MDR.ConclusionA decision tree using readily available clinical characteristics may be helpful to identify pediatric patients at higher risk of bloodstream infection due to an MDRGN organism resistant to common empirical antibiotic therapy.Figure 1.Decision tree. Risk of resistance presented as percentage. Abbreviations: Y- yes; N- no. Gray hexagons represent high-risk of multidrug-resistant (MDR) groups while squares represent low-risk of MDR groups.Disclosures All authors: No reported disclosures.

High Potency of Melaleuca alternifolia Essential Oil against Multi-Drug Resistant Gram-Negative Bacteria and Methicillin-Resistant Staphylococcus aureus.

Purpose: Herein, an extended investigation of Tea tree oil (TTO) against a number of multi-drug resistant (MDR) microorganisms in liquid and vapor phases is reported. Methods: The activity of TTO was tested against methicillin-sensitive Staphylococcus aureus (MSSA), Escherichia coli, and clinical strains of methicillin-resistant S. aureus (MRSA), extended-spectrum beta lactamases producer carbapenem-sensitive Klebsiella pneumoniae (ESBL-CS-Kp), carbapenem-resistant K. pneumoniae (CR-Kp), Acinetobacter baumannii (CR-Ab), and Pseudomonas aeruginosa (CR-Pa). Minimal inhibitory/bactericidal concentrations (MIC/MBCs) and synergistic activity between TTO and different antimicrobials were determined. In the vapor assay (VP), TTO-impregnated discs were placed on the lid of a petri dish and incubated for 24 h at 37 °C. Results: TTO showed a potent bactericidal activity against all the tested microorganisms. TTO in combination with each reference antimicrobial showed a high level of synergism at sub-inhibitory concentrations, particularly with oxacillin (OXA) against MRSA. The VP assay showed high activity of TTO against CR-Ab. Conclusion: Evaluation of in-vitro activity clearly indicated TTO as a potential effective antimicrobial treatment either alone or in association with known drugs against MDR. Therefore, TTO could represent the basis for a possible role in non-conventional regimens against S. aureus and Gram-negative MDR. TTO in VP might represent a promising option for local therapy of pneumonia caused by CR-Ab.

Colistin-based Treatment of Multidrug-resistant Gram-negative Bacterial Pulmonary Infections After Lung Transplantation

BackgroundLung transplantation (LT) is a viable option for a select group of patients with end-stage lung disease. However, infections are a major complication after LT, accounting for significant morbidity and mortality. Several germs may be responsible; multidrug-resistant Gram-negative (MDR-GN) bacteria are emerging. Colistin is widely used in the treatment of these infections and is administered by inhalation and/or parenterally. At our institution, in patients with tracheostomy, colistin is administered by direct instillation in the airway during bronchoscopy. We reviewed a series of patients who underwent LT complicated by postoperative MDR-GN bacterial pulmonary infection. MethodsFrom January 2015 to May 2017, 26 lung transplants were performed. In the postoperative course, 14 (54%) developed MDR-GN bacterial infection; respiratory specimen culture, blood tests, and chest X-ray were considered. Colistin was the only antibiotic usable. Thirteen patients received intravenous (IV) colistin; in the subgroup of patients with tracheostomy, colistin was instilled directly in the airway, and 6 patients received inhaled colistin. ResultsSeven patients needed tracheostomy. Pseudomonas aeruginosa was the predominant infection (86%), with Acinetobacter baumanii seen in 2 cases (14%). An early clinical-laboratory response was observed in 9 patients (64%). White blood cell count and C-reactive protein values improved (P = .02 and P = .001, respectively). A significant reduction in bacterial load was observed on microbiologic bronchoalveolar lavage specimens. ConclusionColistin instilled directly in the airway did not show side effects. The combination of IV and inhaled/instilled colistin could be a useful treatment option for MDR-GN infections after LT.

Sequence- and structure-based computational analyses of Gram-negative tripartite efflux pumps in the context of bacterial membranes

Gram-negative multidrug resistance currently presents a serious threat to public health with infections effectively rendered untreatable. Multiple molecular mechanisms exist that cause antibiotic resistance and in addition, the last three decades have seen slowing rates of new drug development. In this review, we summarize the use of various computational techniques for investigating the mechanisms of multidrug resistance mediated by Gram-negative tripartite efflux pumps and membranes. Recent work in our lab combines data-driven sequence and structure analyses to study the interactions and dynamics of these bacterial components. Computational studies can complement experimental methodologies for gaining crucial insights into combatting multidrug resistance.

Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli and Acinetobacter baumannii among horses entering a veterinary teaching hospital: The contemporary "Trojan Horse".

Pathogens frequently associated with multi-drug resistant (MDR) phenotypes, including extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae (ESBL-E) and Acinetobacter baumannii isolated from horses admitted to horse clinics, pose a risk for animal patients and personnel in horse clinics. To estimate current rates of colonization, a total of 341 equine patients were screened for carriage of zoonotic indicator pathogens at hospital admission. Horses showing clinical signs associated with colic (n = 233) or open wounds (n = 108) were selected for microbiological examination of nostril swabs, faecal samples and wound swabs taken from the open wound group. The results showed alarming carriage rates of Gram-negative MDR pathogens in equine patients: 10.7% (34 of 318) of validated faecal specimens were positive for ESBL-E (94%: ESBL-producing Escherichia coli), with recorded rates of 10.5% for the colic and 11% for the open wound group. 92.7% of the ESBL-producing E. coli were phenotypically resistant to three or more classes of antimicrobials. A. baumannii was rarely detected (0.9%), and all faecal samples investigated were negative for Salmonella, both directly and after two enrichment steps. Screening results for the equine nostril swabs showed detection rates for ESBL-E of 3.4% among colic patients and 0.9% in the open wound group, with an average rate of 2.6% (9/340) for both indications. For all 41 ESBL-producing E. coli isolated, a broad heterogeneity was revealed using pulsed-field gel electrophoresis (PFGE) patterns and whole genome sequencing (WGS) -analysis. However, a predominance of sequence type complex (STC)10 and STC1250 was observed, including several novel STs. The most common genes associated with ESBL-production were identified as blaCTX-M-1 (31/41; 75.6%) and blaSHV-12 (24.4%).The results of this study reveal a disturbingly large fraction of multi-drug resistant and ESBL-producing E. coli among equine patients, posing a clear threat to established hygiene management systems and work-place safety of veterinary staff in horse clinics.

Comparing the Outcomes of Adults with Enterobacteriaceae Bacteremia Receiving Short-Course vs Prolonged-Course Antibiotic Therapy

BackgroundThe recommended duration of antibiotic treatment for Enterobacteriaceae bacteremia is between 7 and 14 days. We compared the clinical outcomes of patients receiving short-course (6–10 days) vs prolonged-course (11–15 days) antibiotic therapy for Enterobacteriaceae bacteremia.MethodsA retrospective cohort study was conducted at The Johns Hopkins Hospital, The University of Maryland Medical Center, and The Hospital of the University of Pennsylvania including patients with monomicrobial Enterobacteriaceae bacteremia treated with in vitro active antibiotic therapy in the range of 6–15 days between 2008 and 2014. 1:1 nearest neighbor propensity score matching without replacement was performed, prior to regression analysis, to estimate the risk of all-cause mortality within 30 days after the end of antibiotic treatment for patients receiving short vs. prolonged durations of antibiotic therapy. Secondary outcomes included Clostridium difficile infection (CDI) and the emergence of multidrug-resistant Gram-negative (MDRGN) bacteria within 30 days after the end of antibiotic therapy.ResultsA total of 1,769 patients met eligibility criteria. There were 385 matched pairs who were well-balanced on baseline characteristics. The median duration of therapy in the short-course group and prolonged-course group was 8 days (interquartile range (IQR) 7–9 days) and 15 days (IQR 13–15 days), respectively. No difference in all-cause mortality between short- and prolonged-course treatment groups was observed (adjusted hazard ratio [aHR] 1.00; 95% CI 0.62–1.63). Rates of CDI were similar between the treatment groups (OR 1.17; 95% CI 0.39–3.51). There was a non-significant protective effect of short-course antibiotic therapy on the emergence of MDRGN bacteria (OR 0.59; 95% CI 0.32–1.09 P = 0.09).ConclusionShort courses of antibiotic therapy yields similar clinical outcomes to prolonged courses of antibiotic therapy for Enterobacteriaceae bacteremia, and may protect against subsequent MDRGN emergence.Disclosures All authors: No reported disclosures.

Intestinal colonization of residents of long-term care facilities and nursing homes in Braga area with Multidrug-resistant Gram-negatives

Intestinal colonization of residents of long-term care facilities and nursing homes in Braga area with Multidrug-resistant Gram-negatives

Low prevalence of colonization with multidrug-resistant gram-negative bacteria in long-term care facilities in Graz, Austria

Residents in long-term care facilities (LTCFs) are increasingly found to be an important reservoir of multidrug-resistant gram-negative (MRGN) bacteria. We aimed to determine colonization by MRGN bacteria over 6 months in LTCFs and geriatric wards in Graz, Austria, and to evaluate risk factors for such colonization. During August 2015, we conducted a point-prevalence survey at LTCFs and geriatric wards of the Geriatric Health Centers of the City of Graz. Inguinal and perianal swabs were taken from 137 patients and screened for MRGN using standard procedures. Six months after the initial investigation all colonized patients were sampled again and use of antibiotics, hospital admissions, and mortality was registered. Genetic relatedness of MRGN bacteria was evaluated. We detected 12 patients harboring MRGN isolates (prevalence, 8.7%). Overall inguinal colonization was 5.1%. After 6 months, only 2 out of 12 patients were still colonized. Presence of a urinary catheter was associated with a higher risk of MRGN colonization (odds ratio [OR], 17.5; 95% CI, 1.6-192). Chronic wounds and gastrostomy were also risk factors of MRGN colonization (OR, 10.7; 95% CI, 1.6-69.3 and OR, 18.3; 95% CI, 2.4-139.4, respectively). There was no difference in mortality between colonized and noncolonized patients. Prevalence of colonization with MRGN bacteria was low in patients in LTCFs and geriatric wards in Graz, Austria.

Specific Clinical Profile and Risk Factors for Mortality in General Surgery Patients with Infections by Multi-Drug-Resistant Gram-Negative Bacteria.

The incidence of gram-negative multi-drug-resistant (MDR) infections is increasing worldwide. This study sought to determine the incidence, clinical profiles, risk factors, and mortality of these infections in general surgery patients. All general surgery patients with a clinical infection by gram-negative MDR bacteria were studied prospectively for a period of five years (2007-2011). Clinical, surgical, and microbiologic parameters were recorded, with a focus on the identification of risk factors for MDR infection and mortality. Incidence of MDR infections increased (5.6% to 15.2%) during the study period; 106 patients were included, 69.8% presented nosocomial infections. Mean age was 65 ± 15 years, 61% male. Extended-spectrum β-lactamases (ESBL) Escherichia coli was the most frequent MDR bacteria. Surgical site infections and abscesses were the most common culture locations. The patients presented multiple pre-admission risk factors and invasive measures during hospitalization. Mortality was 15%, and related to older age (odds ratio [OR] 1.07), malnutrition (OR 13.5), chronic digestive conditions (OR 4.7), chronic obstructive pulmonary disease (OR 3.9), and surgical re-intervention (OR 9.2). Multi-drug resistant infections in the surgical population are increasing. The most common clinical profile is a 65-year-old male, with previous comorbidities, who has undergone a surgical intervention, intensive care unit (ICU) admission, and invasive procedures and who has acquired the MDR infection in the nosocomial setting.

Prevalence of MDR pathogens of bacterial meningitis in Egypt and new synergistic antibiotic combinations.

The aim of this study was identifying bacterial pathogens involved in meningitis, studying their antibiotic resistance profiles, investigating the antibiotic resistance genes as well as evaluating the use of various antibiotic combinations. Antibiotic susceptibility tests were evaluated according to CLSI guidelines. Antibiotic combinations were evaluated by calculating the Fractional Inhibitory Concentration (FIC) index. A total of 71 bacterial isolates were recovered from 68 culture positive CSF specimens. Sixty five of these isolates (91.5%) were recovered from single infection specimens, while 6 isolates (8.4%) were recovered from mixed infection specimens. Out of the 71 recovered isolates, 48 (67.6%) were Gram-positive, and 23 (32.4%) were Gram-negative. Thirty one of the Gram positive isolates were S. pneumoniae (64.6%, n = 48). Out of the recovered 71 isolates; 26 (36.6%) were multidrug-resistant (MDR) isolates of which, 18 (69.2%) were Gram-negative and 8 (30.8%) were Gram-positive. All MDR isolates (100%) showed resistance to penicillin and ampicillin, however, they showed lower resistance to meropenem (50%), levofloxacin (50%), amikacin (48%), pipercillin-tazobactam (45.8%). Most common antibiotic resistance genes were investigated including: tem (21.1%), shv (15.8%), ctx-m (15.8%) coding for TEM-, SHV, CTX-M extended-spectrum beta-lactamases (ESBLs), respectively; aac(6')-I b(26.3%) coding for aminoglycoside 6’-N-acetyltransferase type Ib ciprofloxacin resistant variant; and qnrA (5.3%) gene coding for quinolone resistance. The DNA sequences of the respective resistance genes of some selected isolates were PCR amplified, analyzed and submitted to the GenBank database under the accession numbers, KX214665, KX214664, KX214663, KX214662, respectively. The FIC values for ampicillin/sulbactam plus cefepime showed either additive or synergistic effect against ten tested Gram-negative MDR isolates, while doxycycline plus levofloxacin combination revealed synergism against two MDR Gram-positive isolates. The results indicate high prevalence of antibiotic resistance among MDR isolates. Therefore, new guidelines should be implemented in Egypt to rationalize the use and avoid the misuse and abuse of antimicrobial agents.

Flavonoids from Maytenus buchananii as potential cholera chemotherapeutic agents

Maytenus buchananii is worldwide distributed small evergreen tree traditionally used as anti-tumor, anti-ulcer, anti-inflammatory, and as antimicrobial. The column chromatography of the MeOH extract of M. buchananii leaves followed by purification of different fractions led to the isolation of nine known flavonoids. Their structures were elucidated on the basis of spectrum analysis, and by comparison with those from the literature. The antibacterial activity was assessed by performing minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and the time-kill kinetic study while the antioxidant activity was determined by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and trolox equivalent antioxidant capacity (TEAC) assays. All of the extracts/compounds showed antibacterial activity against the strains of Gram-positive bacteria, Staphylococcus aureus, and Gram-negative multi-drug resistance bacteria, Vibrio cholerae (causative agent of cholera) and Shigella flexneri (causative agent of shigellosis). Compounds 2 (MIC=32 to 128μg/mL) and 6 (MIC=16 to 64μg/mL) showed the largest antibacterial activities with the best MIC (16μg/mL) recorded with compound 6 on S. aureus. The results of both DPPH and TEAC assays found compounds 3 (EC50=1.38μg/mL; TEAC=89.69μg/mL), 5 (EC50=1.56μg/mL; TEAC=90.93μg/mL) and 6 (EC50=1.42μg/mL; TEAC=89.76μg/mL) to exhibit the most antioxidant activity. Results obtained from this study may help to exploit the use of the M. buchananii leaf extracts and some of their flavonoid compounds as pharmacological ingredients for promoting health, especially for cholera/shigellosis and chronic diseases associated with oxidative stress.

Outcomes of Rapid Identification of Multi-Drug Resistant Gram-Negative Organisms Causing Bacteremia in Combination with Antimicrobial Stewardship in a Community Health System.

BackgroundRapid initiation of effective antibiotic therapy has been strongly associated with a decrease in mortality in gram-negative (GN) bacteremia. In an effort to improve time to effective antibiotic therapy in the treatment of multi-drug resistant (MDR) GN bacteremia, we implemented Verigene GN Blood Culture (BC-GN) assay, which can rapidly identify GN bacteria at the genus/species level and specific resistance markers from blood cultures within 2 hours of positivity.MethodsThe objective of this multi-center, pre-post quasi-experimental study was to assess outcomes of Verigene BC-GN in combination with antibiotic stewardship in treatment of MDR GN bacteremia. A retrospective chart review was performed one year prior and four months post-implementation of Verigene BC-GN. Patients > 18 years old with MDR GN bacteremia identified by Verigene BC-GN within 5 days of admission were included. The primary endpoint was time to effective antibiotic therapy for MDR GN bacteremia. Secondary outcomes included overall and ICU length of stay (LOS) and 30-day mortality. Education regarding interpretation of resistance markers and selection of optimal antibiotic therapy was provided to pharmacists and physicians prior to implementation.ResultsA total of 110 patients were included, 86 in the pre-intervention group and 24 in the post-intervention group. Mean time to effective antibiotic therapy decreased significantly from 47.6 ± 23.1 vs. 18.8 ± 9.1 hours, respectively (P < 0.0001). Median overall LOS was 6.0 vs 5.5 days (P = 0.88), ICU LOS was 3.0 vs 4.0 days (P = 0.57), and 30-day mortality was 4.7% vs 4.2% (P = 1) pre and post-implementation, respectively.ConclusionVerigene BC-GN, in combination with antibiotic stewardship, successfully improved time to effective antibiotic therapy among MDR GN organisms causing bacteremia.Disclosures All authors: No reported disclosures.

Assessment of a Healthcare-Associated Pneumonia (HCAP) Risk Stratification and Empiric Treatment Guideline: A New Antimicrobial Stewardship Initiative

BackgroundRisk stratification of HCAP patients is a possible Antimicrobial Stewardship (AST) intervention for the treatment of multidrug resistant (MDR) Gram-negative (GN) vs. community-acquired pneumonia (CAP) pathogens. This study assessed the impact of a risk stratification guideline for empiric antimicrobial selection relative to acceptance rates and clinical outcomes.MethodsIn 2017, a guideline for inpatients with HCAP was launched. High risk (HR) of MDR GN was defined as patients admitted to the intensive care unit (ICU), or with >1 risk factor including: receipt of any antimicrobial within 30 days or broad spectrum antimicrobials within 90 days, hemodialysis dependence, or immunocompromised. HR patients were recommended to receive antimicrobials covering MDR GN and low-risk patients to narrower CAP regimens. Patients treated for HCAP post guideline implementation were compared with a historic 2014 cohort for guideline concordance, antimicrobial selection, and clinical outcomes. AST interventions were also assessed.ResultsOverall, 105 patients in the post-implementation period were compared with 309 historic patients. Guideline-concordant risk-stratified therapy increased 13% [95% CI (3%, 24%)] overall. Clinical failure rates were similar with 11% vs 10% (P = 0.608) in the pre- and post-implementation periods, with an 84% AST acceptance rate (Figure 1). Treatment length decreased [8.1 to 6.6 days (P < 0.001)] and de-escalation increased [31% to 72% (P < 0.001)] as seen in Table 1.ConclusionIntroduction of a risk stratified guideline through AST intervention changed practice by matching MDR risk with empiric HCAP therapy. Failure rates were comparable. Secondary benefits included: decreased treatment duration and hospital stay, increased de-escalation rates and decreased MDR GN antimicrobial use in low-risk patients.Disclosures All authors: No reported disclosures.

Multidrug-resistant Gram-negative bacteria-resistant infections: epidemiology, clinical issues and therapeutic options

In the last decade, we have witnessed a dramatic increase in the number of multidrug resistant Gram-negative (MDRGN) bacterial pathogens, both in Italy and worldwide, with Enterobacteriacae (mostly Klebsiella pneumoniae), Pseudomonas aeruginosa and Acinetobacter baumannii being the major threats in clinical practice. Inadequate empirical antimicrobial therapy of severe infections caused by MDR Enterobacteriacae has been associated with an increased morbidity and mortality. However, a careful selection of patients who may receive empirical treatment covering MDR Enterobacteriacae is important to avoid the overuse of broad-spectrum antibiotics. The aim of this review is to describe the mechanism of resistance, epidemiology, risk factors, clinical issues, and therapeutic options for MDRGN pathogens.

In vitro Activity of Ceftolozane/Tazobactam Alone or with an Aminoglycoside Against Multi-Drug-Resistant Pseudomonas aeruginosa from Pediatric Cystic Fibrosis Patients.

IntroductionGram-negative multi-drug resistance is an emerging threat among pediatric patients with cystic fibrosis (CF). Ceftolozane/tazobactam (C/T) is an extended-spectrum cephalosporin/beta-lactamase inhibitor combination that has been shown to maintain activity against MDR P. aeruginosa isolates. The understanding of C/T effectiveness in pediatric patients is extremely limited. Minimum inhibitory concentration (MIC) testing and time-kill analyses were performed to better understand the antimicrobial susceptibility and potential role of C/T.MethodsNon-duplicate clinical respiratory MDR P. aeruginosa isolates (n = 5) from four pediatric CF patients were identified. MICs were determined for these isolates using CLSI broth microdilution methods. Time-kill analyses were performed using multiples of C/T alone, and combinations of C/T 2× and 8× the MIC with 30 mg/L tobramycin or 80 mg/L amikacin for all isolates. Cell counts were determined by serial dilution plating.ResultsIsolates had variable susceptibilities to C/T (range 0.5–8 mg/L), tobramycin (range 2 to >64 mg/L) and amikacin (range 8 to >256 mg/L). Time-kill analyses revealed an average of 0.71 (range −0.6 to 4.4), 1.50 (range 0.8–2.0) and 2.1 (range 1.2–3.4) log-kill at 4×, 8× and 16× the C/T MIC, respectively. At a tobramycin MIC of 32 mg/L, combination therapy showed synergistic benefit when the isolate was C/T susceptible. C/T and amikacin combination therapy showed synergistic activity at an amikacin MIC >256 mg/L when C/T MIC was 2 mg/L (4.7 log-kill at 2× C/T MIC and 4.0 log-kill at 8× C/T MIC).ConclusionC/T appears to be a promising treatment option for treatment of MDR P. aeruginosa in pediatric CF patients, both alone and in combination with tobramycin or amikacin. Interestingly, the benefit of C/T combination therapy with amikacin may be more pronounced than with the addition of tobramycin. Further evaluation of such combination regimens in pediatric CF patients is warranted.

Pre-Transplant Colonization By a Multidrug-Resistant Gram Negative Bacteria Has No Impact on Overall Survival and Mortality after Hematopoietic Stem Cell Transplantation: A Single-Center Experience in 362 Patients

Multidrug resistant Gram-negative (MDR-GN) bacteria are responsible for severe infections in immune-compromised hosts. Clinical outcome is often poor, especially in patients undergoing hematopoietic stem cell transplantation (HSCT) with mortality rates exceeding 50%. In patients with a documented pre-transplant MDR-GN bacterial infection, HSCT is usually regarded as a potentially harmful procedure, despite its curative potential. Recently, active surveillance strategies based on rectal swab evaluation have been recommended with the aim of early identification of MDR-GN carriers, although they are not routinely performed in every transplant center.After an Institutional outbreak of K. pneumoniae carbapenemase -producing (KPC-Kp) infections in our Centre in June 2012, we decided to start an Institutional programme of active surveillance. No patient was excluded from HSCT, despite a documented colonization. In this study, we retrospectively analysed the results of the active surveillance programme and the impact of a pre-transplant colonization on HSCT outcomes.From July 2012 to January 2016 (43 months), 362 consecutive patients (254 undergoing allogeneic HSCT (allo-HSCT) and 108 autologous HSCT (auto-HSCT) were examined. All patients had a pre-transplant rectal swab evaluable. Blood cultures were performed at each febrile episode. Neutropenic patients developing fever were treated according to internal antimicrobial guidelines, usually with multiple targeted antimicrobial therapy in case of a previously known MDR-GN bacterial colonization. Median follow-up was of 602 days.Pre-transplant carriers were 8% and 17% in auto-HSCT and allo-HSCT recipients, respectively. Both in auto-HSCT and allo-HSCT, 30% of carriers were colonized by KPC-Kp. Among auto-HSCT, the overall survival (OS) did not significantly differ in carriers versus non-carriers (86% vs 84% at 2 years; P=0.231). Moreover, neither transplant-related mortality (TRM) nor infection-related mortality (IRM) were significantly different among the two groups, being of 0% vs 4% at 100 days (P=0.32) and of 0% vs 2% at 100 days (P= 0.099), respectively. In allo-HSCT, the OS was not significantly influenced by the carrier status nor univariate (43% vs 50% at 2 years; P=0.091) or in multivariate analysis (HR 1.41; P=0.129). Furthermore, TRM and IRM were comparable in MDR-GN bacteria carriers versus non-carriers, being 31% vs 25% at 2 years (P=0.301) and 23% vs 14% at 2 years (P=0.304). A MDR-GN bacterial colonization was not an independent risk factor for TRM and IRM, with an hazard ratio (HRs) of 1.428 (P=0.268) and of 1.69 (P=0.215). Furthermore, we did not observe any significant variation in the incidence of severe acute GvHD when comparing carriers and non-carriers (HR 1.86; P=0.087). In multivariate analysis severe acute GvHD was the only independent factor for a worse OS, TRM and IRM ( HRs of 3.177 (P< 0.001), 7,933 (P< 0.001) and 18,690 (P < 0.001), respectively.We registered a total of 168 Gram-negative bloodstream infections (BSIs) and 41/168 (24%) were due to a MDR bacteria, of which 6/41 in auto-HSCT patients and 35/41 in allo-HSCT recipients. Extended spectrum β-lactamases (ESBL+) E. coli (39%) and KPC-Kp (24%) were most frequently isolated from blood cultures.Thanks to the early initiation of a combined antimicrobial therapy guided by the antimicrobial susceptibly test deriving from rectal swabs in patients developing neutropenic fever, we witnessed a significant reduction in 30-day MDR-GN bacteria-related mortality (0% for auto-HSCT and 17% for allo-HSCT patients). Noticeably, in our Center 30-day KPC-Kp-related mortality was only 30%.Our retrospective single-centre study was able to demonstrate that, both in auto-HSCT and allo-HSCT, a pre-transplant colonization status is not significantly associated with a reduced OS, nor with a reduced TRM and IRM. Moreover, the prompt initiation of an adequate empirical therapy based on information coming from rectal swab is able to reduce MDR-GN bacteria-related mortality and to improve the overall HSCT outcome. DisclosuresCiceri:MolMed SpA: Consultancy.

Longitudinal Microbiome Profile in Allogeneic Hematopoietic Stem Cell Transplantation: Results of a Prospective Study in 100 Patients

BACKGROUND: Allogeneic HSCT (allo-HSCT) is the only cure for several patients with hematological malignancies. Recent advances in therapies have significantly reduced transplant-related mortality (TRM); nevertheless infections and graft-versus-host disease (GvHD) still represent major complications. Recent studies indicate that patients undergo dramatic alterations of intestinal microbiota during allo-HSCT, potentially affecting the outcome. An alarming emergence of gram-negative multi-drug-resistant (GN-MDR) pathogens has been increasingly reported from various cancer centers, and the primary site of colonization is mainly the gut. Moreover, GvHD was associated with major shifts in the composition of intestinal microbiota, able to modulate the severity of intestinal inflammation.METHODS: Between October 2014 and March 2016, we have conducted a prospective observational study to examine the intestinal microbiota by NGS techniques in 100 consecutive adult patients, who received allo-HSCT for high-risk hematological malignancies (63.5% acute leukemia). Stem cell donors were family haploidentical (n=45), HLA identical sibling (n=15), unrelated volunteer (n=35), cord blood (n=5). Stem cell source was mainly T-cell replete PBSCs. Fecal specimens have been collected before conditioning (T0), during aplasia (T10) and after engraftment (T30). The fecal microbiome have been analyzed using the 454 GS Junior System, and QIIME software. We defined a threshold of normality for the main phyla on the basis of the control.RESULTS:We observed an important difference in relative percentages of phyla populating the gut between our pts and control. Our patients showed a progressive reduction of the intestinal microbial diversity (alpha diversity) during the transplant process, with a specific decrease of anaerobic species belonging to both Bacteroidetes and Firmicutes phyla, and a relative increase of facultative anaerobic gram-positive families such as Enterococcaceae and Staphylococcaceae. A great variation was observed, particularly between T0 and T30, where we found a significant decrease in alpha diversity (p < 0.001).A significantly different distribution in the baseline microbiome was reported in patients who will experience different clinical outcomes. Patients (n=23) who developed a microbiologically-confirmed sepsis show an increase of Proteobacteria phylum (cut-off 5%; p<0.01, RR= 5.38), and a decrease in Lachnospiraceae (cut-off 10%; p 0.02 and RR=2.77). Sepsis by GN-MDR bacteria (n=15) was strongly associated to an increase of Proteobacteria phylum (p<0.01 and RR=5.38 at T0). Microbiome changes preceded the development of severe sepsis and septic shock in 21 patients (increase of Proteobacteria, p 0.01 and RR= 2.43), underlying its potential for the prediction of these clinically relevant conditions and its impact on overall survival (increase of Proteobacteria p<0.01 and RR= 2.69; decrease in Lachnospiraceae, p<0.01 and RR=2.83).We identified by multivariate analysis some associations between the relative increase of a specific phylum and clinical variables at baseline. Previous allo-HSCT and prior infections represented strong risk factors for developing colonization by Proteobacteria (exceeding 5%). Sepsis by GN-MDR bacteria was associated to increase in Enterobacteriaceae(exceeding 5%; p 0.011).Interestingly, significant microbioma changes were observed at 10 days after transplant, in patients who developed a subsequent acute GvHD, with a predominant role played by gram-positive bacteria belonging to Firmicutes. More in details, the presence of Lachnospiraceae was associated to a decreased risk of developing acute GvHD (p=0.04 and RR= 4.35), whereas dominance of Enterococcaceae (p<0.01 and RR=3.23) and Staphylococcaceae (p<0.01 and RR=3.5) was associated to its increased incidence.CONCLUSIONS:Longitudinal study of microbioma profile allows early identification of patients at risk for major transplant-related complications such as sepsis by GN-MDR or acute GvHD, offering a new tool for individualized pre-emptive or therapeutical strategies to improve the outcome of allo-HSCT. DisclosuresCiceri:MolMed SpA: Consultancy.

Chlorhexidine bathing for the prevention of colonization and infection with multidrug-resistant microorganisms in a hematopoietic stem cell transplantation unit over a 9-year period: Impact on chlorhexidine susceptibility.

Health care associated infections (HAIs) are currently among the major challenges to the care of hematopoietic stem cell transplantation (HSCT) patients. The objective of the present study was to evaluate the impact of 2% chlorhexidine (CHG) bathing on the incidence of colonization and infection with vancomycin-resistant Enterococcus (VRE), multidrug-resistant (MDR) gram-negative pathogens, and to evaluate their CHG minimum inhibitory concentration (MIC) after the intervention.A quasi-experimental study with duration of 9 years was conducted. VRE colonization and infection, HAI rates, and MDR gram-negative infection were evaluated by interrupted time series analysis. The antibacterial susceptibility profile and mechanism of resistance to CHG were analyzed in both periods by the agar dilution method in the presence or absence of the efflux pump inhibitor carbonyl cyanide-m-chlorophenyl hydrazone (CCCP) and presence of efflux pumps (qacA/E, qacA, qacE, cepA, AdeA, AdeB, and AdeC) by polymerase chain reaction (PCR).The VRE colonization and infection rates were significantly reduced in the postintervention period (P = 0.001). However, gram-negative MDR rates in the unit increased in the last years of the study. The CHG MICs for VRE increased during the period of exposure to the antiseptic. A higher MIC at baseline period was observed in MDR gram-negative strains. The emergence of a monoclonal Pseudomonas aeruginosa clone was observed in the second period.Concluding, CHG bathing was efficient regarding VRE colonization and infection, whereas no similar results were found with MDR gram-negative bacteria.

Anticancer and antibacterial secondary metabolites from the endophytic fungus Penicillium sp. CAM64 against multi-drug resistant Gram-negative bacteria.

The emergence of multiple-drug resistance bacteria has become a major threat and thus calls for an urgent need to search for new effective and safe anti-bacterial agents. This study aims to evaluate the anticancer and antibacterial activities of secondary metabolites from Penicillium sp., an endophytic fungus associated with leaves of Garcinia nobilis. The culture filtrate from the fermentation of Penicillium sp. was extracted and analyzed by liquid chromatography-mass spectrometry, and the major metabolites were isolated and identified by spectroscopic analyses and by comparison with published data. The antibacterial activity of the compounds was assessed by broth microdilution method while the anticancer activity was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The fractionation of the crude extract afforded penialidin A-C (1-3), citromycetin (4), p-hydroxyphenylglyoxalaldoxime (5) and brefelfin A (6). All of the compounds tested here showed antibacterial activity (MIC = 0.50 - 128 µg/mL) against Gramnegative multi-drug resistance bacteria, Vibrio cholerae (causative agent of dreadful disease cholera) and Shigella flexneri (causative agent of shigellosis), as well as the significant anticancer activity (LC50 = 0.88 - 9.21 µg/mL) against HeLa cells. The results obtained indicate that compounds 1-6 showed good antibacterial and anticancer activities with no toxicity to human red blood cells and normal Vero cells.

Endoscopic ultrasound-guided drainage of abdominal fluid collections after pancreatic surgery: Efficacy and long-term follow-up.

Endoscopic ultrasound-guided drainage (EUS-GD) of postoperative abdominal fluid collections (POFC) following pancreatic surgery is used as an alternative or complement to percutaneous drainage (PD) procedure. The present single-center retrospective study evaluates its efficacy and safety. We included consecutive cases with POFC treated by EUS-GD between September 2009 and November 2014 in our department. Technical success, long-term clinical success, recurrence rate and need for surgery were analyzed. 24 procedures in 20 patients (95 % after pancreatic resection) were assessed. Indications for surgery included tumors/lesions located in the pancreas (15/20), chronic pancreatitis (3/20) and duodenal adenoma not completely resectable endoscopically (2/20). EUS-GD was performed within a median of 30 days (IQR: 8.25) for a median fluid collection size of 72.5 mm (IQR: 46.25), requiring a mean of 1.2 sessions with placement of a mean of 2.1 plastic stents (7 Fr/10 Fr) per patient for a mean of 89 days (IQR: 127). Microbiology of aspirated fluid revealed positive cultures in 13 patients, mostly polymicrobial, isolated positive for fungal and 3 multidrug-resistant gram negative (MRGN) in 4 cases. An additional transpapillary drainage was inserted in 1/20 patients. 4/20 patients received PD, mostly before EUS-GD. Technical and clinical success was achieved in 20/20 (100 %) and 18/20 (90 %) patients, respectively, while 2 patients required re-operation. During follow-up (median 630 days after stent removal, range: 45 - 2160), recurrence occurred in 1/18 (5.5 %) patient that was referred for surgery. No death or severe adverse events were noted. EUS-GD is an effective, minimally invasive and safe method for therapy of POFC after pancreatic surgery offering long-term remission in about 95 % of cases.