Pathogens Of Bacteremia Research Articles

Early detection of bacteremia pathogens with rapid molecular diagnostic tests and evaluation of effect on intensive care patient management

İntroductionThe BioFire FilmArray Blood Culture Identification panel (BCID2), a rapid molecular blood culture identification test based on multiplex nested polymerase chain reaction. The aim of this study was to evaluate clinical outcomes between the period before (pre-BCID2 group) and after (post-BCID2 group) the introduction of the BCID2 panel into our routine practice. MethodsThe primary endpoint was time to optimal antibiotherapy, and the secondary endpoints were duration of hospital and intensive care unit stay, 7-day, 14-day and 28-day mortality rates after bacteremia. ResultsThe median time from empirical antibiotherapy to optimal antimicrobial therapy was 4560 (IQR;3060-7140) minutes in the pre-BCID2 group and 1715 (IQR;1362- 2776.25) minutes (in the post-BCID2 group (p<0.05). ConclusionAdding the BCID2 panel may improve antibiotic management in critically ill bacteremia patients

The Impact of an Antimicrobial Stewardship Program on Days of Therapy in the Pediatric Center: An Interrupted Time-Series Analysis of a 19-Year Study.

We aimed to analyze the effects of an antimicrobial stewardship program (ASP) on the proportion of antimicrobial-resistant pathogens in bacteremia, antimicrobial use, and mortality in pediatric patients. A retrospective single-center study was performed on pediatric inpatients under 19 years old who received systemic antimicrobial treatment from 2001 to 2019. A pediatric infectious disease attending physician started ASP in January 2008. The study period was divided into the pre-intervention (2001-2008) and the post-intervention (2009-2019) periods. The amount of antimicrobial use was defined as days of therapy per 1,000 patient-days, and the differences were compared using delta slope (= changes in slopes) between the two study periods by an interrupted time-series analysis. The proportion of resistant pathogens and the 30-day overall mortality rate were analyzed by the χ². The proportion of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae bacteremia increased from 17% (39 of 235) in the pre-intervention period to 35% (189 of 533) in the post-intervention period (P < 0.001). The total amount of antimicrobial use significantly decreased after the introduction of ASP (delta slope value = -16.5; 95% confidence interval [CI], -30.6 to -2.3; P = 0.049). The 30-day overall mortality rate in patients with bacteremia did not increase, being 10% (55 of 564) in the pre-intervention and 10% (94 of 941) in the post-intervention period (P = 0.881). The introduction of ASP for pediatric patients reduced the delta slope of the total antimicrobial use without increasing the mortality rate despite an increased incidence of ESBL-producing gram-negative bacteremia.

235. Investigation of the relationship between the number of positive blood cultures and patient prognosis

Abstract Background The relationship between the number of positive blood cultures (NPBCs) and clinical outcomes has not been well-studied. The purpose of this study was to assess the impact of NPBCs (one set or two) on clinical outcomes. Methods We conducted a retrospective study comparing the clinical features of two sets of positive blood cultures (NPBCs=2) and one set of positive blood culture (NPBCs=1) in adult patients with bacteremia and fungemia from 2004 to 2021 at a tertiary hospital in Tokyo, Japan. We focused on four pathogens commonly encountered in clinical practice, including Staphylococcus aureus (S. aureus), Streptococci, gram-negative rods (GNR) (Enterobacterales and Pseudomonas aeruginosa), and Candida species, as the true causative pathogens in bacteremia and fungemia. The primary outcome was in-hospital mortality, and secondary outcomes were ICU admission and use of vasopressor drugs. Results In univariate analysis, NPBCs=2 for S. aureus was associated with vasopressor use, and NPBCs=2 for Streptococci was linked to a higher rate of ICU admission. However, these differences were not significant in multivariate analysis. Interestingly, NPBCs=2 for S. aureus had a positive impact on in-hospital mortality compared with NPBCs=1 (OR 0.574, 95%CI 0.376–0.877, p &amp;lt; 0.05). NPBCs for Candida species did not affect clinical outcomes. Furthermore, NPBCs=2 for GNR was associated with vasopressor use (OR 1.62, 95%CI 1.27–2.07, p &amp;lt; 0.05) in both univariate and multivariate analysis. We performed logistic regression analysis using the five items with the highest clinical significance: NPBCs=2, serum Cr &amp;gt; 1.2 mg/dL, Hb &amp;lt; 12 g/dL, heart rate &amp;gt; 90 beats/min, and platelet count &amp;lt; 150,000/μL. Based on the β coefficient, we assigned scores to each item and created a STAT-2 (S: Serum Cr, T: Thrombocytopenia, A: Anemia, T: Tachycardia, 2: NPBCs=2) score for the use of hypertensive drugs for GNR. The receiver operating characteristic (ROC) curve for the STAT-2 score with a cutoff of 6 points or higher had an area under the curve (AUC) of 0.763. The specificity was 90.8%, with a positive likelihood ratio of 4.13 (95% CI 3.40-5.02). Conclusion Our study suggests that NPBCs can predict clinical outcomes in patients with certain pathogenic infections. Disclosures All Authors: No reported disclosures

Analysis of the structure of bacteremia and sensitivity to antibiotics of microorganisms isolated in intensive care units in an emergency hospital in the period from 2003 to 2021: a retrospective observational study

INTRODUCTION: Creation of protocols for effective empiric antimicrobial therapy is impossible without the analysis of current antibiotic susceptibility data. OBJECTIVE: Analysis of changes in the etiological significance of the leading pathogens of bacteremia in the ICU (intensive care unit) in the period from 2003 to 2021, and their sensitivity to antibiotics; study of the types of carbapenemases in the most relevant pathogens — Klebsiella pneumoniae and Acinetobacter baumannii. MATERIALS AND METHODS: The analysis included all microorganisms isolated from the blood of patients who were in the medical 12-bed ICU in the emergency hospital of Moscow in the period from 2003 to 2021. Identification of microorganisms and determination of antibiotic sensitivity were carried out with an automatic PHOENIX analyzer and a standardized disco diffusion method. Detection of carbapenemases was carried out by PCR (polymerase chain reaction). RESULTS: In the period from 2003 to 2021, 17 034 blood samples were examined, from which 6372 microorganisms were isolated. During this period, the proportion of Gram-negative microorganisms increased from 21.0 to 52.8 %, mainly due to K. pneumoniae from 1.0 to 24.5 % and A. baumannii from 0 to 9.1 %. The resistance of these microorganisms to carbapenems increased significantly from 2008 to 2021: K. pneumoniae from 2.3 % to 70.3 %, A. baumannii — from 7.5 to 99.5 %. K. pneumoniae produced the following types of carbapenemases: OXA-48 (73.8 %), KPC (6.2 %), NDM 1.5 %, NDM + OXA-48 (15.4 %), KPC + OXA-48 (3.1 %). All A. baumannii strains produced OXA-40 type carbapenemase. OXA-48 carbapenemase producers were resistant to colistin and tigecycline in 14.6 and 44.8 %, and to ceftazidime/avibactam in 4.2 %. CONCLUSIONS: The increased level of antimicrobial resistance in recent years among Gram-negative microorganisms isolated from blood is a very significant problem in the ICU. Most K. pneumoniae strains are characterized as multi-drug resistant, about 10 % of the strains were categorized as extremely-drug resistant (XDR) or pan-drug resistant. All strains of A. baumannii belong to the category of XDR.

1832. Epidemiology, risk factors for mortality and resistance associated with Stenotrophomonas maltophilia bacteremia at a tertiary care hospital in Korea over 7 years

Abstract Background Stenotrophomonas maltophilia (SM) is an important emerging nosocomial pathogen. This study aimed to describe the epidemiological, clinical, and microbiological charateristics of SM bacteremia at a tertiary care hospital in Korea over 7 years. Methods A retrospective study was conducted at a 1150-bed tertiary care hospital in Busan, South Korea. Data were collected between January, 2013 and November, 2019. Results A total of 79 bacteremia patients (median age: 61 years; 62% males) were reviewed; 38 (48.1%) were in 2013-2016 and 41 (51.9%) were in 2017-2019. The overall SM bacteremia-related 30-days mortality was 31.6%. Susceptibility to levofloxacin, sulfamethoxazole-trimethoprim (SMX/TMP) and minocycline were 87.3%, 92.4% and 100%, respectively. The most common clinical syndrome was central line-associated bloodstream infection (n=37, 46.8%). The others were intra-abdominal infection (n=18, 22.8%), skin and soft tissue infection (n=5, 6.3%) and pneumonia (n=5, 6.3%). In 50.6%, SM was the only pathogen of bacteremia, whereas in 49.4%, more than one causative organisms were isolated. Acinetobacter baumanii (in 8 cases) was the most frequent co-isolated pathogen, followed by Enterococcus faecium (in 6 cases), Pseudomonas aeruginosa (in 5 cases), Staphylococcus epidermidis (in 5 cases), Enterococcus gallinarum (in 3 cases) and Klebsiella pneumoniae (in 3 cases). Age (OR, 6.60; 95% Cl, 1.59-27.41; P = 0.009), inappropriate antimicrobial treatment (OR, 3.47; 95% Cl, 1.14-10.56; P = 0.029), and levofloxacin-resistant strains (OR, 7.86; 95% Cl, 1.20-51.41; P = 0.031) were independent risk factors for SM bacteremia-related 30-days mortality in multivariate analysis. Conclusion SM bacteremia has a high early mortality rate. In our study, old age, inappropriate antimicrobial treatment and levofloxacin-resistant strains were significant independent risk factors for early mortality in SM bacteremia patients. Early diagnosis and immediate use of appropriate antibiotics are recommended to improve mortality of SM bacteremia. Disclosures All Authors: No reported disclosures.

W134 High flux screening of 4 most common bacteremia pathogens using isothermal amplification platform

W134 High flux screening of 4 most common bacteremia pathogens using isothermal amplification platform

СПЕКТР ВОЗБУДИТЕЛЕЙ БАКТЕРИЕМИЙ У ДЕТЕЙ

The analysis of the results of bacteriological examination of blood samples of patients aged from 1 month to 18 years was carried out. A retrospective analysis was carried out based on the results of the virus-bacteriological laboratory of the City Children's Infectious Clinical Hospital of Minsk for the period from 2009 to 2020. It was found that gram-positive bacteria predominate in the spectrum of bacteremia pathogens in patients (59.4%), among which coagulase-negative types of staphylococci dominate, which corresponds to numerous modern studies from other countries, according to which the most common pathogens of bacteremia are coagulase-negative staphylococci.

Risk factors of bacteremia in children hospitalized with community-acquired pneumonia: A nested case-control study

ObjectiveTo assess the risk factors of bacteremia in children hospitalized with community-acquired pneumonia (CAP). Study designThe present, nested, case-control study enrolled a cohort of patients with CAP aged < 18 years who were hospitalized at Tokyo Metropolitan Children’s Medical Center or Tama-Hokubu Medical Center between March 2010 and February 2018. Among the cohort with blood cultures (BCs), patients with bacteremia were identified and matched with five control patients based on their treatment facility, underlying disease, and age. Conditional logistic regression was used to calculate the odds ratios (ORs) of bacteremia for risk factor candidates. ResultsBCs were obtained for 2,383 (84%) of the 2,853 patients in the CAP cohort. Of those with BCs, 34 (1.4%) had bacteremia. S. pneumoniae and H. influenzae accounted for 26 (76%) and four (12%) instances of the bacteremia pathogens, respectively. Bacteremia occurred more frequently among patients hospitalized in the spring than during other seasons (P = 0.022). On multivariate analysis, the severity of pneumonia was not associated with bacteremia incidence (OR: 0.92 [0.30–2.85]) while a white blood cell count > 16,000/μL (OR: 5.90 [2.14–16.3]) was shown to be a significant risk factor. The OR of the need for a ventilator on admission day was significantly high (28.4 [3.02–1374]) on univariate analysis, but the subject pool was too small to determine its significance on multivariate analysis. ConclusionsThe results of the present study supported BC collection in patients with leukocytosis and in those requiring ventilator use on admission.

Chryseobacterium indologenes as a Rare Pathogen of Bacteremia in Febrile Neutropenia

Chryseobacterium indologenes (C. indologenes) is nonmotile, oxidase-, and indole-positive gram-negative aerobic bacillus. Immunosuppression, comorbidities, use of broad-spectrum antibiotics are known risk factors for C. indologenes-related infections. We report a neutropenic fever caused by C. indologenes in a 16-month-old boy who was treated due to the neuroblastoma. According to the antimicrobial susceptibility test result, he was treated with cephaperazone/sulbactam.

Clinical characteristics of bloodstream infection by Parvimonas micra: retrospective case series and literature review

BackgroundGram-positive anaerobic (GPA) bacteria inhabit different parts of the human body as commensals but can also cause bacteremia. In this retrospective observational study, we analyzed GPA bacteremia pathogens before (2013–2015) and after (2016–2018) the introduction of the matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS).MethodWe conducted a retrospective observational study by searching the microbiology database to identify all positive GPA blood cultures of patients with GPA bacteremia diagnosed using the new technique, MALDI-TOF MS, between January 1, 2016 and December 31, 2018; and using a conventional phenotypic method between January 1, 2013 and December 31, 2015 at a single tertiary center in Japan. Parvimonas micra (P. micra) (17.5%) was the second most frequently identified GPA (MALDI-TOF MS); we then retrospectively reviewed electronic medical records for 25 P. micra bacteremia cases at our hospital. We also conducted a literature review of published cases in PubMed from January 1, 1980, until December 31, 2019; 27 cases were retrieved.ResultsMost cases of P. micra bacteremia were identified after 2015, both, at our institute and from the literature review. They were of mostly elderly patients and had comorbid conditions (malignancies and diabetes). In our cases, laryngeal pharynx (7/25, 28%) and gastrointestinal tract (GIT; 6/25, 24%) were identified as the most likely sources of bacteremia; however, the infection source was not identified in 9 cases (36%). P. micra bacteremia were frequently associated with spondylodiscitis (29.6%), oropharyngeal infection (25.9%), intra-abdominal abscess (14.8%), infective endocarditis (11.1%), septic pulmonary emboli (11.1%), and GIT infection (11.1%) in the literature review. Almost all cases were treated successfully with antibiotics and by abscess drainage. The 30-day mortalities were 4 and 3.7% for our cases and the literature cases, respectively.ConclusionsInfection sites of P. micra are predominantly associated with GIT, oropharyngeal, vertebral spine, intra-abdominal region, pulmonary, and heart valves. Patients with P. micra bacteremia could have good prognosis following appropriate treatment.

Clinical relevance of procalcitonin values in bacteremia

IntroductionThe aim of this study was to investigate procalcitonin levels according to the causative pathogens of bacteremia. The relationships between the clinical outcomes and procalcitonin levels were also studied. MethodsFrom among 452 patients, 507 cases of positive blood culture were included in the present study. Procalcitonin levels were studied according to the pathogen types. The prevalence of septic shock and the mortality rates were also studied in four groups stratified by the procalcitonin levels (groups 1, 2, 3, and 4 had procalcitonin levels of <0.5 ng/mL, 0.5 ≤ 2.0 ng/mL, 2.0 < 10 ng/mL, and ≥10 ng/mL, respectively). ResultsThe procalcitonin levels were significantly higher in bacteremia cases with Gram-negative rods (19.50 ng/mL), such as Escherichia coli (32.5 ng/mL), than those with Gram-positive rods (8.45 ng/mL) or Gram-positive cocci (9.21 ng/mL) (p < 0.01). The 28-day mortality rates in groups 1, 2, 3, and 4 were 6.0%, 12.0%, 14.9%, and 19.8%, respectively. The procalcitonin levels of samples taken before or on the same day of blood cultures were significantly lower than those taken one day after blood cultures. Multiple logistic regression analysis showed that C-reactive protein and procalcitonin ≥10 ng/mL were independently associated with a higher risk of mortality within 28 days. ConclusionsThe PCT levels were higher in cases of bacteremia caused by GNR than those caused by GPR or GPC. The 28-day mortality rate increased as the PCT levels increased. Clinical importance of early evaluations and appropriate interpretation of procalcitonin levels for bacteremia were indicated.

Flavobacteriaceae Bacteremia in Children: A Multicenter Study.

The Flavobacteriaceae family includes rare pathogens in children; Chryseobacterium indologenes and Elizabethkingia meningosepticum are the most common pathogenic species, with a wide range of clinical presentations and high mortality rate. Although rare, diagnosis is important due to inherent resistance to multiple antibiotics, especially those typically prescribed for empiric treatment of aerobic Gram-negative bacterial infections. A multicenter retrospective study conducted in 5 Israeli hospitals, describing Flavobacteriaceae bacteremia confirmed by positive blood culture from 1998 to 2018. Thirteen cases were included; 9 isolates were C. indologenes. Bacteremia was nosocomial or healthcare-associated in all cases. Bacteremia was associated with young age (median, 1 year, range 24 days-17 years), with only 2 (15.4%) cases in neonates, Central line-associated bloodstream infection as a source (5/13, 38%) and malignancy (7/13, 54.8%). Thirty-day all-cause mortality was 23% (3/13). Ninety-one percent of isolates were susceptible to trimethoprim-sulfamethoxazole, 82% to piperacillin-tazobactam and 92% to ciprofloxacin. C. indologenes and E. meningosepticum are rare, nosocomial- or healthcare-associated pediatric bacteremia pathogens. Bacteremia was associated with young age, but in contrast to the literature, the majority of our cases were older than the neonatal age period. In addition, they were associated with central line-associated bloodstream infection and malignancy. The most adequate antibiotics according to resistance patterns were ciprofloxacin, trimethoprim-sulfamethoxazole and piperacillin-tazobactam.

2182. Harnessing Direct-from-Blood MALDI-TOF (DBM) and Local Blood Stream Infection (BSI) Antibiogram Data to Direct Optimal Therapy for Gram-Negative Rod (GNR) Bacteremia

BackgroundGNR bacteremia is common in the hospital environment. Drug-resistance challenges thoughtful use of, and timely de-escalation to, regimens that limit carbapenem use. DBM accurately provides rapid identification of bacteremia pathogens, but lacks antibiotic susceptibility testing (AST) results to aid clinicians in refining therapy. We investigated whether integrating DBM identification and local BSI antibiogram data could be used to identify carbapenem-sparing regimens with predicted efficacy of ≥ 95% prior to traditional AST results.MethodsWe identified GNR blood culture results in adults from January 1, 2018 to December 31, 2018. The first isolate per bacteremia episode per patient was analyzed. AST was performed by MicroScan. We categorized isolates into 1 of 3 groups based on the most common resistance mechanisms in our population (i.e. CTX-M ESBL, AmpC): 1] Escherichia spp. and Klebsiella spp. (EK), 2] S. marscecens, P. mirabilis, E. (Klebsiella) aerogenes, C. freundii, M. morganii, E. cloacae complex, and C. non-freundii (SPEC-MEC), and 3] P. aeruginosa (PA). We compiled susceptibility rates to common antibiotics for GNR sepsis and compared results using Chi-square.Results381 GNR isolates were recovered in blood cultures from adult patients in 2018: EK 264 (69%), SPEC-MEC 66 (17%), PA 36 (9%), other 15 (4%). Susceptibility results in common GNR sepsis agents are shown in Figure 1 (*P < 0.05 between groups). Within each organism group, susceptibility was highest in the following scenarios: 1] EK: PTZ and MEM (P < 0.05 vs. FEP, TOB, CIP, and ATM), 2] SPEC-MEC: FEP, TOB, and MEM (P < 0.05 vs. PTZ and ATM), and 3] PA: comparably similar (> 90%) for PTZ, FEP, TOB, and MEM.ConclusionIntegration of DBM and antibiogram data identified species-specific carbapenem-sparing regimens that would predict ≥ 95% of patients with GNR bacteremia are on effective therapy prior to traditional AST results. In appropriate patients, this could lead to a significant reduction in carbapenem duration and avoid broad-scale carbapenem use while also optimizing time to effective therapy. This is a readily adaptable process for other centers to improve care of patients with GNR bacteremia. Our data suggest using β-lactam alternatives for GNR bacteremia, especially EK, should be done with caution. DisclosuresAlexander Lepak, MD, Paratek Pharmaceuticals: Research Grant; Tetraphase Pharmaceuticals: Research Grant.

Microbiological profiles of pathogens causing nosocomial bacteremia in 2011, 2013 and 2016

To dynamically investigate the distribution and antimicrobial resistance profiles of bacteremia pathogens isolated from different regions in China in 2011, 2013 and 2016. Non-repetitive isolates from nosocomial bloodstream infections were retrospectively collected and detected for antimicrobial susceptibility tests (AST) by agar dilution or microbroth dilution methods. Whonet 5.6 was used to analyze the AST data. Among 2 248 isolates, 1 657 (73.7%) were Gram-negative bacilli and 591 (26.3%) were Gram-positive cocci. The top five bacteremia pathogens were as follows, Escherichia coli (32.6%, 733/2 248), Klebsiella pneumoniae (14.5%, 327/2 248), Staphylococcus aureus (10.0%, 225/2 248), Acinetobacter baumannii (8.7%, 196/2 248) and Pseudomonas aeruginosa (6.2%, 140/2 248). Colistin (96.5%, 1 525/1 581, excluding innate resistant organisms), tigecycline (95.6%, 1 375/1 438, excluding innate resistant organisms), ceftazidine/clavulanate acid (89.2%, 1 112 /1 246), amikacin (86.4%, 1 382/1 599) and meropenem (85.7%, 1 376/1 605) showed relatively high susceptibility against Gram-negative bacilli. While tigecycline, teicoplanin and daptomycin (the susceptibility rates were 100.0%), vancomycin and linezolid (the susceptibility rates were 99.7%) demonstrated high susceptibility against Gram-positive cocci. The prevalence of extended-spectrum β-lactamases (ESBLs)-producing Enterobacteriaceae were 50.6% (206/407), 49.8% (136/273) and 38.9% (167/429) in 2011, 2013 and 2016 respectively; carbapenem-non-susceptible Enterobacteriaceae were 2.2% (9/408), 4.0% (16/402) and 3.9% (17/439) in 2011, 2013 and 2016 respectively; The prevalence of multidrug-resistant A. baumannii (MDRA) was 76.4% (55/72) in 2011, 82.7% (43/52) in 2013 and 87.5% (63/72) in 2016, respectively. The prevalence of multidrug-resistant P. aeruginosa (MDRP) was 9.8% (5/51) in 2011, 20.0% (7/35) in 2013 and 13.0% (7/54) in 2016, respectively. The prevalence of methicillin-resistant S. aureus (MRSA) was 51.9% (41/79) in 2011, 29.7% (19/64) in 2013 and 31.7% (26/82) in 2016, respectively. The prevalence of high level gentamicin resistance (HLGR) of Enterococcus faecium and Enterococcus faecalis were 43.2% (48/111) and 40.9% (27/66), respectively. The predominant organism of carbapenem-non-susceptible Enterobacteriaceae was K. pneumoniae with its proportion of 57.1% (24/42). Among 30 tigecycline-non-susceptible Enterobacteriaceae, K. pneumoniae was the most popular organism with 76.7% (23/30). Among 39 colistin-resistant Enterobacteriaceae, E. coli, Enterobacter cloacae and K. pneumoniae were constituted with the percent of 43.6 (17/39), 35.9 (14/39) and 15.4 (6/39), respectively. The Gram-negative bacilli (E. coli and K. pneumoniae were the major organisms) were the major pathogens of nosocomial bacteremia, to which tigecycline, colistin and carbapenems kept with highly in vitro susceptibility. Whereas, among the Gram-positive cocci, S. aureus was the top 1 isolated organism, followed by E. faecium, to which tigecycline, daptomycin, linezolid, vancomycin and teicoplanin kept with highly in vitro susceptibility. Isolation of colistin-resistant Enterobacteriaceae, tigecycline-non-susceptible Enterobacteriaceae, linezolid- or vancomycin-non-susceptible Gram-positive cocci suggests more attention should be paid to these resistant organisms and dynamic surveillance was essential.

Bacteremia Due to &lt;i&gt;Bacillus subtilis&lt;/i&gt;：A Case Report and Clinical Evaluation of 10 Cases

A 59-year-old male presented with fever, and was admitted for bacteremia due to gram-positive rod. All 5 sets of blood cultures obtained prior to the initiation of vancomycin tested positive for Bacillus subtilis. Based on the susceptibility test result, the antibiotics were changed to levofloxacin to complete a total of fourteen days treatment. The patient recovered without relapse over one year. Despite thorough examinations, the portal of entry of B. subtilis remained unclear. We retrospectively reviewed ten cases of bacteremia due to B. subtilis over 5 years in our hospital. The cases with positive B. subtilis blood cultures which were evaluated as contamination were excluded from the review. The most common portal of entry of B. subtilis was secondary bacteremia due to perforation or ileus (70%), followed by an unknown site (30%). B. subtilis should be considered not only as a contaminant but also as a true pathogen of bacteremia.

The clinical feature and outcomes of severe aplastic anemia patients suffered from bacteremia following antithymocyte globulin

目的分析抗胸腺细胞球蛋白（ATG）治疗后合并血流感染的重型再生障碍性贫血（SAA）患者的临床特征、近期疗效及预后。方法回顾性分析2000年1月至2011年7月行ATG治疗的264例SAA患者的临床特征，并分析合并血流感染患者的细菌学特征及其发生血流感染的危险因素，观察其近期（治疗后3、6个月）疗效，并进行远期预后分析。结果264例患者中有49例（18.6%）ATG治疗后出现血流感染。49例患者中男31例，女18例，中位年龄20 (4~62）岁，其中极重型AA（VSAA) 38例，SAA 11例，治疗后至发生血流感染的中位时间为13 (2~233）d。大肠埃希菌、铜绿假单胞菌和肺炎克雷伯杆菌为最常见的菌种，分别占28.4%、20.9％及14.9%。23例（46.9%）患者合并耐药菌血流感染。VSAA患者ATG治疗后血流感染发生率为28.4%（38/134），显著高于SAA患者的8.5%（11/130）（P<0.001）。VSAA（RR=4.77，95%CI 1.97~11.52，P=0.001）、ATG治疗前1周仍合并感染（RR= 4.76，95%CI 2.05~11.11，P<0.001）是患者发生血流感染的危险因素。ATG治疗后血流感染患者与无感染者比较，3个月血液学反应率分别为10.6％及35.6%（P<0.001），6个月血液学反应率分别为17.0％及55.6%（P<0.001）；5年OS率分别为36.4%（95%CI 21.3%~51.5%）及74.5%（95%CI 68.4%~80.7%）（P< 0.001）。结论①VSAA患者ATG治疗后血流感染发生率高于SAA；②VSAA和ATG治疗前合并感染为发生血流感染的危险因素；③ATG治疗后合并血流感染患者较无感染者近期疗效及远期预后差。

Bacteremia due to Rothia mucilaginosa after chemotherapy for myeloid malignancies

The number of reported cases of bacteremia due to Rothia mucilaginosa (R. mucilaginosa), a component of the normal flora of human gastrointestinal tract mucosa, is limited. We encountered three cases of bacteremia due to R. mucilaginosa during neutropenia after chemotherapy for myeloid malignancies. Although all three patients were successfully treated with antimicrobial agents, one patient developed disseminated lesions in the lungs and soft tissue. The portal of R. mucilaginosa bacteremia is reportedly mucositis or dental disorders; however, no such complications were identified in our patients. Even in the absence of a preexisting portal, R. mucilaginosa should be recognized as a potential causative pathogen of bacteremia during neutropenic periods. Accumulations of cases and isolates are required to further elucidate the risk factors for developing R. mucilaginosa bacteremia, its clinical course, and the optimal antimicrobial treatment.

CAUSATIVE AGENT OF BACTEREMIA AND INTESTINAL MICROBIOTA IN RECIPIENTS OF DONOR LIVER

Aim. To study microbiota of the intestinal tract of recipients with cirrhosis of the liver lobes before transplantation and its association with postoperative bacteremia pathogens. Materials and methods . Microbiota of the intestinal tract was studied in 235 recipients (1–17 years) prior to transplantation of the liver fragment from a related donor (2005–2014). Microbiological study of intestinal contents, trachea, blood, vascular catheters was performed by plating a material on the standard culture medium. Identifi cation was carried out using microbial BD Crystal panels and BBL Crystal MIND databases. Susceptibility of isolated opportunistic bacteria to antibiotics was investigated by disk diffusion method. Results. Deep microecological disturbances in the intestinal tract in children were revealed. All recipients showed the reduction of resident microbiota with reduced content of bifi dobacteria, lactobacilli and coliform bacteria. The growth rate of isolating opportunistic Gram-negative bacteria, especially Klebsiella and enterobacteria (up 100%) was detected. Non-fermenting Gram-negative bacteria, in particularly, Pseudomonas aeruginosa were isolated rarely. Among Gram-positive bacteria dominated coagulase-negative staphylococci (CoNS). In patients with unremarkable post-transplant period (Group 1) CoNS and enterococci were often isolated. In the blood of patients with complicated postoperative period (Group 2) Pseudomonas aeruginosa (44%) and Klebsiella pneumoniae (36%) were isolated. Similar microorganisms were seeded from vascular catheters of the same patients. It is worth noting that no essential differences in the content of Klebsiella and non-fermenting microorganisms in microbiota of the intestinal tract of the recipients of both groups were not determined. Conclusion. Studies showed deep microecological disorders of the intestinal microbiota. Klebsiella pneumonia was the main pathogen, whose high content was detected in all liver lobe recipients studied. Isolation of Klebsiella pneumonia in the blood was 23,7% in patients with complicated postoperative period, and 12,9% in those with unremarkable post-transplant period. No such dependence was revealed in relation to Pseudomonas aeroginosa.

O1-20-1 - Recent Trends of Bacteremia in Patients with Hematological Malignancy

Background: Bacteremia remains a major cause of life-threatening complication in patients with hematological malignancy. Catheter-related bloodstream infections (CRBSI) are a leading cause of nosocomial infections associated with significant mortality and costs. The aim of our study was to inventory the recent trends in epidemiology and incidence of microorganisms causing bacteremia in patients with hematological malignancy.Methods: We performed a retrospective case series analysis of 502 laboratory confirmed episodes of bacteremia at hematology unit of Tsukuba University Hospital between 2010 and 2013. The major pathogens of bacteremia were investigated for their frequency, clinical background and susceptibility. Among the all cases of bacteremia, we investigated the rate of CRBSI.Results: Of 3617 blood specimens cultured, 502 (13.8%) were positive. Among the isolates, 94.8% were aerobic or facultative anaerobic bacteria, 1.0% anaerobes, and 4.2% fungi. Staphylococcus epidermidis (19.3%) was isolated most frequently, followed by Escherichia coli (12.0%), alpha-hemolytic Streptococcus (7.4%), methicillin-resistant Staphylococcus aureus (6.8%), Stenotrophomonas maltophilia (5.4%), and Coagulase negative Staphylococcus (4.6%). The proportion of the microorganisms did not change remarkably during the study period. Although the number of bacteremia didn't almost change between 2010 and 2012 (149 cases/year), it significantly decreased in 2013 (55 cases/year). A total number of 48 CRBSI were observed during the study period. A significantly lower rate of CRBSI was observed in patients who were inserted peripherally inserted central catheter (PICC) compared with the patients who were inserted conventional central venous catheter (CVC) (PICC: 1.0/1000 catheter days, CVC: 5.2/1000 catheter days, P < 0.01).Conclusion: The results will contribute to safer management of patients with hematological malignancy by improving the choice of antibiotics and devices.

THE SPECTRUM OF BACTEREMIA PATHOGENS IN PATIENTS WITH IMMUNE DEFICIENCY STATES OF VARIOUS ORIGINS

Abstract. A comparative analysis of the results of bacteriological study of blood samples obtained from 1608 patients with secondary immunodeficiency of different origins has been conducted. It was established that within the spectrum of pathogens of bacteremia in these onco-urological profile patients, enterobacteria was the predominant one. In post–liver transplantation patients micromycete was predominant, and for wounded patients and victims with serious injuries staphylococci were more often isolated.