Agents Of Bloodstream Infections Research Articles

Evaluation of Blood Cultures from SARS-CoV-2-Positive and Negative Adult Patients.

Bacteremia and fungemia are significant causes of morbidity and mortality that frequently occur as co-infections with viral respiratory infections, including SARS-CoV-2. The aim of this study was to evaluate the microorganisms that were isolated from the blood cultures of SARS-CoV-2-positive and negative patients and investigate their antimicrobial resistance patterns. A retrospective analysis was performed of 22,944 blood cultures sent to the laboratory between November 2020 and December 2021. Blood culture analyses were performed using the BD Bactec FX automated system. Identification was carried out using conventional methods, namely, VITEK-2 and MALDI-TOF MS. Antibacterial/antifungal susceptibility tests were performed according to EUCAST/CLSI recommendations. SARS-CoV-2 tests were performed with RT-PCR. Culture positivity was detected in 1630 samples from 652 patients. Of these 652 patients, 633 were tested for SARS-CoV-2; 118 (18.6%) were positive and 515 (81.3%) were negative. The bacteria and fungi that were isolated at the highest rate in SARS-CoV-2-positive patients were methicillin-resistant coagulase-negative staphylococci (MR-CoNS) (21.5%), Escherichia coli (12.4%), Klebsiella pneumoniae (12.4%), Candida albicans (1.65%), and Candida glabrata complex (1.65%), while in the negative patients, the highest rates were for E. coli (21.3%), MR-CoNS (13.5%), K. pneumoniae (12.05%), C. albicans (2.1%), Candida parapsilosis (1.1%), and Candida tropicalis (0.9%). No statistically significant difference was determined between COVID-19-positive and negative patients in terms of detection, such as with the Pseudomonas spp., Enterococcus spp., and methicillin-resistant Staphylococcus aureus isolated from the blood cultures (p > 0.05). The most common isolate was MR-CoNS in SARS-CoV-2-positive patients (p = 0.028). Acinetobacter baumannii was more frequent (p = 0.004) and carbapenem-resistant K. pneumoniae was isolated at a higher rate (60% vs. 43%) in SARS-CoV-2-positive patients compared to SARS-CoV-2-negative patients (p > 0.05). These findings highlight the fact that isolation procedures should not be disregarded and the distribution of bacterial/fungal agents of bloodstream infections and their antibiotic resistance should be followed up during a pandemic, such as in the case of COVID-19.

A Clinical and Demographic Profile of Elderly (>65 Years) in the Medical Intensive Care Units of a Tertiary Care Center.

The elderly population in India is expected to increase to 319 million by 2050. Managing critically ill elderly patients in intensive care units (ICUs) is a difficult task. Proper planning and development of healthcare infrastructure are of prime importance to face this challenge. To study the clinical profile and outcomes of elderly patients admitted to the medical ICUs. A time-bound, prospective observational study on elderly patients admitted to medical ICUs for more than 48 hours was conducted from March 2019 to September 2020. The demographic, biochemical, hematologic, and microbiological data on antibiotic susceptibility patterns on various organisms and procalcitonin (PCT) reports were collected. Acute Physiology and Chronic Health Evaluation II (APACHE II) score was calculated. Various treatment modalities, such as mechanical ventilation, inotropes, hemodialysis, antibiotics, culture report in sepsis patients, and length of ICU stay were collected. The age of the patients and the length of their ICU stay were not significantly associated with outcomes. Sepsis and APACHE II scores are significantly associated with outcomes. Receipt of mechanical ventilation, vasopressor support, and hemodialysis are significantly associated with mortality (p < 0.001). The patients' ages were not significantly associated with outcomes. The most common cause of death among elderly patients was found to be sepsis, followed by pneumonia. In elderly ICU patients, gram-negative organisms are the most common causative agents in bloodstream infections. The APACHE II score, sepsis, receipt of mechanical ventilation, vasopressor support, and hemodialysis are significantly associated with mortality. Prabhudev P, Ramamoorthi K, Acharya RV. A Clinical and Demographic Profile of Elderly (>65 Years) in the Medical Intensive Care Units of a Tertiary Care Center. Indian J Crit Care Med 2023;27(3):166-175.

Invitro Activity of Tigecycline against Multidrug-Resistant Enterobacteriaceae from Blood Stream Infection in a Tertiary Care Hospital of Nepal

Background: Multidrug resistant (MDR) enterobacteriaceae like extended spectrum beta lactamase (ESBL) and metallo-beta lactamase (MBL) are being encountered as the causative agents of blood stream infection. To overcome this, accurate diagnosis of MDR pattern with appropriate antibiotics is required. Tigecycline is a broad spectrum antibiotic which exhibit strong activity against MDR enterobacteriaceae. This study is aimed to find out resistance pattern like ESBL and MBL with invitro activity of tigecycline against enterobacteriaceae. Methods: A descriptive cross-sectional study was conducted in the Department of Microbiology, B.P. Koirala Institute of Health Sciences, from 1st September 2014 to 31st August 2015. Confirmation for ESBL was done as recommended by Clinical and Laboratory Standard Institute (CLSI) and MBL production was detected by double disk synergy test. Antibiotic sensitivity test against tigecycline was done by Kirby-Bauer disk diffusion method. Results: 192 (1.70%) enterobacteriaceae were isolated throughout the study. Among them, 94 (49%) were ESBL, 51 (26.5%) were carbapenemase and 22 (11.5%) were MBL producers. A total of 64 (33.4%) isolates were found to be MDR. None of the isolates was resistant against tigecycline. Conclusion: Tigecycline is found to have excellent invitro activity against MDR enterobacteriaceae from BSI.

Evaluation of Microbiologically Documented Bloodstream Infections in Pediatric Hematology/Oncology Patients: Results of Ten Years

Inpediatric hematology/oncology patients, infections are the main cause of prolonged hospital stay, increased mortality and high cost following relapse or progression. In this patient group, infections caused by multi-drug resistant bacteria are common and affect morbidity and mortality rates. We aimed to determine the frequency and antibiotic susceptibility of bacteria isolated from blood cultures of the patients with malignant and non-malignant diseases in our hospital over a ten-year period. patients admitted to the Pediatric Hematology/Oncology Service between January 2011- June 2021 were evaluated. The most common disease was acute lymphoblastic leukemia (27%). The first isolated bacteria of same species for each patient were included, contaminated cultures were not included. Blood cultures incubated in the Bactec FX automated blood culture system for five days. Bacteria were identified by conventional methods or automated systems. Antibiotic susceptibility tests were performed by disc diffusion or gradient test and were evaluated according to guidelines. A total of 4631 blood culture samples from 296 patients were analyzed. Positive signal was seen in 620 samples. Blood culture posivity was 13.4%. Total 298 blood culture samples were evaluated. Gram positive bacteria rate were 59% and 41% gram negative. The most frequently (58.7%) isolated gram positive bacteria were methicillin-resistant coagulase negative staphylococci and gram negative bacteria were Klebsiella pneumoniae (28,5%). The rate of bacteria producing extended spectrum beta lactamase (ESBL) was detected as 74% for Escherichia coli and 69% for Klebsiella pneumoniae . It is important for each center to determine its own causative agents and their resistance patterns in bloodstream infections. Gram positive bacteria were found dominantly in our study. The high ESBL rate in E.coli and K.pneumoniae isolates is remarkable. Early detection of the causative agents in bloodstream infections of the pediatric hematology/oncology patients and initiation of prompt treatment are important to reduce mortality.

Direct DNA Sequencing-Based Analysis of Microbiota Associated with Hematological Malignancies in the Eastern Province of Saudi Arabia.

Introduction Bloodstream infections (BSI) among patients with hematological malignancies (HM) could predispose them to higher morbidity and mortality for various underlying conditions. Several microorganisms, either pathogenic or opportunistic normal human flora, could cause severe bacteremia and septicemia. While conventional methods have their own limitations, molecular methods such as next-generation sequencing (NGS) can detect these blood infections with more reliability, specificity, and sensitivity, in addition to information on microbial population landscape. Methodology. Blood samples from HM patients (n = 50) and volunteer blood donor control individuals with no HM (n = 50) were subjected to 16S rRNA gene amplification using standard PCR protocols. A metagenomic library was prepared, and NGS was run on a MiSeq (Illumina) sequencer. Sequence reads were analyzed using MiSeq Reporter, and microbial taxa were aligned using the Green Genes library. Results 82% of the patients showed BSI with Gram-negative bacteria as the most predominant group. E. coli comprised a major chunk of the bacterial population (19.51%), followed by K. pneumoniae (17.07%). The CoNS and Viridans Streptococci groups are 17.07% and 14.63%, respectively. Other major species were S. aureus (9.75%), P. aeruginosa (7.31%), A. baumannii (4.87%), E. cloacae (4.87%), and P. mirabilis (4.87%). 34.14% of the cases among patients showed a Gram-positive infection, while 14.63% showed polymicrobial infections. Conclusion Most of the BSI in patients were characterized by polymicrobial infections, unlike the control samples. Molecular methods like NGS showed robust, fast, and specific identification of infectious agents in BSI in HM, indicating the possibility of its application in routine follow-up of such patients for infections.

Epidemiology and etiology of blood stream infections in a Belgian burn wound center

ABSTRACT Background Infections are a major cause of morbidity in burn patients. We aimed to investigate the epidemiology and antibiotic susceptibility of blood stream infections in order to gain a better understanding of their role and burden in our Burn Wound Center. Methods This retrospective epidemiological investigation analyzed data derived from medical files of patients admitted to our Burn Wound Center having had at least one positive blood culture between 1 January and 31 December 2018. We focused on the prevalence of causative agents in blood stream infections in function of the time after injury and on their drug sensitivity. Results Among the 363 patients admitted to our Burn Wound Center during the study period, 29 had at least one episode of blood stream infection. Gram-negative organisms accounted for 56,36% of the pathogens in blood stream infections, Gram-positives for 38,17%, and yeasts for 5,45%. Pseudomonas aeruginosa was the most common bacterium (20%), followed by Staphylococcus epidermidis (16.36%), Escherichia coli and Klebsiella pneumoniae (9,09% each). A third of the Gram-negative isolates were multidrug resistant. Gram-positive cocci were isolated from blood cultures at a median of 9 days after the injury, earlier than Gram-negative rods (median 15 days). The main sources of blood stream infections were the burn wounds, followed by infected catheters. Conclusions Multidrug resistant bacteria must be considered when selecting empirical antibiotic therapy in septic burn patients. In our center, we need to update our antibiotic guidelines, to review the hospital infection control measures and to introduce routine typing technology.

Evaluation of QuickFISH and maldi Sepsityper for identification of bacteria in bloodstream infection

Background: Early detection of bacteria and their antibiotic susceptibility patterns are critical to guide therapeutic decision-making for optimal care of septic patients. The current gold standard, blood culturing followed by subculture on agar plates for subsequent identification, is too slow leading to excessive use of broad-spectrum antibiotic with harmful consequences for the patient and, in the long run, the public health. The aim of the present study was to assess the performance of two commercial assays, QuickFISH® (OpGen) and Maldi Sepsityper™ (Bruker Daltonics) for early and accurate identification of microorganisms directly from positive blood cultures.Materials and methods: During two substudies of positive blood cultures, the two commercial assays were assessed against the routine method used at the clinical microbiology laboratory, Unilabs AB, at Skaraborg Hospital, Sweden.Results: The Maldi Sepsityper™ assay enabled earlier microorganism identification. Using the cut-off for definite species identification according to the reference method (>2.0), sufficiently accurate species identification was achieved, but only among Gram-negative bacteria. The QuickFISH® assay was time-saving and showed high concordance with the reference method, 94.8% (95% CI 88.4–98.3), when the causative agent was covered by the QuickFISH® assay.Conclusions: The use of the commercial assays may shorten the time to identification of causative agents in bloodstream infections and can be a good complement to the current clinical routine diagnostics. Nevertheless, the performance of the commercial assays is considerably affected by the characteristics of the causative agents.

Bacteraemia and antibiotic susceptibility pattern of isolates from patients visiting a private hospital of Kathmandu

Background: Bacteraemia can develop a broad array of complications that may be difficult to recognize initially and can increase morbidity. The study was thus conducted to identify the causative agents of bacteraemia and to assess antibiogram of the isolates among the patients suspected of blood stream infection visiting Everest hospital, New Baneshwor Kathmandu.&#x0D; Methods: Altogether 400 blood cultures were processed during March, 2015 to August, 2015. Standard Operating Procedures (SOPs) was followed during the processing of the specimens. Antibiotic susceptibility testing of bacterial isolates was done by Kirby Bauer disc diffusion method with Muller-Hinton agar using the guidelines and interpretive criteria of the Clinical and Laboratory Standards Institute (CLSI 2013).&#x0D; Result: The positivity of blood culture was found to be 48 (12%). Gram negative bacterial were found to be more predominant 27(56.2%) than gram positive bacteria 21(43.7%) in causing bacteraemia. The most prevalent isolate was Staphylococcus aureus 15 (31.2%) followed by Salmonella Paratyphi A 10 (20.8%) and Salmonella Typhi 8 (16.6%), E. coli &amp; CoNS 4 (8.3%), Pseudomonas aeruginosa 3 (6.2%) and Klebsiella pneumoniae &amp; Streptococcus pneumoniae 2 (4.1%) respectively. All gram-positive isolates were found to be sensitive to Cefoxitin, Ceftriaxone and Vancomycin followed by Ampicillin (90.42%), Erythromycin (85.71%), Ciprofloxacin (83.33%), Doxycycline (75%) and Cephalexin (70.58%) whereas gram negative isolates were sensitive to Ceftriaxone followed by Chloramphenicol (92%), Gentamicin (88.8%), Cefixime (85.71%), Ofloxacin (83.3%) and Amoxycillin and Ciprofloxacin (71.3%)&#x0D; Conclusion: The isolation of etiological agents of blood stream infection should be assessed by proper microbiological analysis and it would be helpful for controlling of the outbreaks of resistance strains through effective empirical therapy.

Identification of microorganisms grown in blood culture flasks using liquid chromatography-tandem mass spectrometry.

Bloodstream infections are a common cause of disease and a fast and accurate identification of the causative agent or agents of bloodstream infections would aid the start of adequate treatment. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) shotgun proteomics method was developed for the identification of bacterial species directly from blood cultures that were simulated by inoculating blood culture bottles with single or multiple clinically relevant microorganisms. Using LC-MS/MS, the single species were correctly identified in 100% of the blood cultures, whereas for polymicrobial infections, 78% of both species were correctly identified in blood cultures. The LC-MS/MS method allows for the identification of the causative agent of positive blood cultures.

In vitro effect of vancomycin and daptomycin on biofilm formation of coagulase-negative staphylococci strains

Coagulase-negative staphylococci (CNS) are one of the primer agents of blood stream infections (BSI) and catheter-related bloodstream infections (CR-BSI) which are associated mostly with the usage of central venous catheters and, important causes of morbidity and mortality despite the usage of antibacterial and supportive treatment. It is important to determine the properties of these causative microorganisms in order to make appropriate treatment of such infections. The aims of our study were to evaluate the biofilm formation of coagulase negative staphylococci (CNS) which were causative agents of bloodstream (BSI) and catheter related bloodstream infections (CR-BSI), to determine the minimum inhibitory concentration (MIC) of planktonic forms and minimal biofilm eradication concentration (MBEC) of sessile forms for vancomycin and daptomycin and to evaluate the efficacy of these antibiotics in infections with biofilm-forming isolates in vitro. A total of 65 CoNS (n= 26 catheter colonizers, n= 28 CR-BSI, n= 11 BSI agents) were identified by conventional methods and also with BD Phoenix (Becton Dickinson, USA) and Bruker Microflex MS (Bruker Daltonics, Germany) systems. Methicillin resistance was determined by the presence of mecA gene with PCR. MIC values of vancomycin and daptomycin were investigated by broth microdilution, for daptomycin medium containing 25 and 50 μg/ml Ca++ were used. Assessment of biofilm formation and detection of MBEC were determined by microplate method. The clonal relationship was investigated by the PFGE method. A total of 65 isolates; 26 catheter colonizers, 28 CR-BSI agents and 11 BSI agents were evaluated and identified as Staphylococcus epidermidis (n= 33), Staphylococcus haemolyticus (n= 16), Staphylococcus hominis (n= 15), and Staphylococcus capitis (n= 1). 81.5% of the isolates were found to be methicillin resistant and all of them were found to be sensitive to vancomycin (MIC= 0.125-4 μg/ml) and daptomycin (MIC= 0.062-0.25 μg/ml in 25 μg/ml Ca++ and MIC= 0.031-0.50 μg/ml in 50 μg/ml Ca++ containing medium). MIC values were lower in medium containing 50 μg/ml Ca++ for daptomycin. As it is known that the efficacy of daptomycin depends on the physiological levels of Ca++, which causes conformational changes in the structure of these antibacterials. Our findings also suggested that high levels of Ca++ are needed to ensure the efficacy of daptomycin. All of the isolates produced biofilm at different strengths of positivity (n= 12/18.5% weak, n= 35/%53.8 moderate, n= 18/%27.7 strong). MBEC and MBEC/MIC values for vancomycin were found to be higher than daptomycin (p< 0.001). Strong biofilm producers had higher MBEC and MBEC/MIC, MBEC50/MIC50 ve MBEC90/MIC90 values (p< 0.05). Especially in infections with biofilm forming isolates, the detection of only MIC values are not always sufficient in the treatment of biofilm-related infections as they reflect the sensitivity of planktonic bacteria. The inconsistency between the MIC and MBEC values and the high rates of MBEC/MIC found in our study supported this prediction.The lower detection of MBEC and MBEC/MIC values of daptomycin compared to the same values of vancomycin suggested that daptomycin might be effective at lower doses than vancomycin in the treatment of biofilm infections.

Factors associated with candidemia by non-albicans Candida group in midwest region of Brazil: Eight-year cross-sectional study

The alarming increase in the non-albicans Candida group (NAC) as the etiologic agent of bloodstream infections has made it necessary for the factors associated with candidemia caused by NAC to be elucidated. A cross-sectional retrospective study was conducted which included analysis of microbiological reports, medical records and hospital infection notifications in two tertiary hospitals (Mato Grosso, Brazil) over 8 years (2006 to 2014). Of 144 observed episodes of candidemia, the NAC group represented 64.6%. The prevalence of candidemia caused by NAC was equal to 1.10 × 1,000 admissions, which was statistically different (p<0.001) from and greater than the prevalence of Candida albicans (CA). Hospitalization in the intensive care unit (PR = 1.83; p = 0.05), length of stay ≥42 days (PR = 0.62; p = 0.01) and the use of H2 blockers (PR = 1.75; p = 0.03) were significantly associated with death in patients with candidemia caused by NAC, regardless of gender, use of central venous catheter, treatment with amphotericin B and mechanical ventilation. The incidence of candidemia caused by NAC was 34% higher in men and 40% higher in patients who remained hospitalized for ≥42 days, regardless of prematurity, neutropenia, catheter, mechanical ventilation and age. After 42 days of hospitalization, the chances of survival were 67.3% among patients with candidemia caused by NAC and 56.4% among patients with candidemia caused by CA. This study suggests a different behavior between CA and NAC groups, which should be especially considered for choice of treatment regimen with antifungals. Key words: Candidemia, nosocomial bloodstream infection, epidemiology, tertiary care centers.

Nanomechanical sensor applied to blood culture pellets: a fast approach to determine the antibiotic susceptibility against agents of bloodstream infections

ObjectivesThe management of bloodstream infection, a life-threatening disease, largely relies on early detection of infecting microorganisms and accurate determination of their antibiotic susceptibility to reduce both mortality and morbidity. Recently we developed a new technique based on atomic force microscopy capable of detecting movements of biologic samples at the nanoscale. Such sensor is able to monitor the response of bacteria to antibiotic's pressure, allowing a fast and versatile susceptibility test. Furthermore, rapid preparation of a bacterial pellet from a positive blood culture can improve downstream characterization of the recovered pathogen as a result of the increased bacterial concentration obtained. MethodsUsing artificially inoculated blood cultures, we combined these two innovative procedures and validated them in double-blind experiments to determine the susceptibility and resistance of Escherichia coli strains (ATCC 25933 as susceptible and a characterized clinical isolate as resistant strain) towards a selection of antibiotics commonly used in clinical settings. ResultsOn the basis of the variance of the sensor movements, we were able to positively discriminate the resistant from the susceptible E. coli strains in 16 of 17 blindly investigated cases. Furthermore, we defined a variance change threshold of 60% that discriminates susceptible from resistant strains. ConclusionsBy combining the nanomotion sensor with the rapid preparation method of blood culture pellets, we obtained an innovative, rapid and relatively accurate method for antibiotic susceptibility test directly from positive blood culture bottles, without the need for bacterial subculture.

Bacterial spectrum and antimicrobial-resistance pattern of bloodstream infections in neutropenic and non-neutropenic adult cancer patients

Background: Bloodstream infections (BSI) in cancer patients remain associated with significant morbidity and mortality. The choice of an empirical antibiotic regimen is usually based on the local epidemiology of the microorganisms and their antimicrobial susceptibility profile. We present the spectrum and the antimicrobial susceptibility of the causative agents of BSI in adult cancer patients in East Sussex Healthcare Trust (ESHT), UK. Materials and Methods: This retrospective study was conducted at ESHT from January 2006 to December 2015. Demographic and laboratory data were collected from the pathology information system. Results: A total of 640 episodes of BSI occurred in 297 patients (159 male). Of the 297 patients, 239 (80%) had haematology malignancies, whereas 54 (18%) had solid organ tumours. Four patients had both. Majority of BSI (383, 60% episode) occurred in neutropenic patients. A total of 802 organisms (477 [59%] and 325 [41%] organisms from neutropenic and non-neutropenic patients, respectively) were isolated. Of 802, 406 (51%) Gram-positive and 386 (49%) Gram-negative organisms were isolated. Seven Mycobacterium species and three Candida species were isolated. Most common organisms in neutropenic patients were coagulase-negative Staphylococcus (CoNS) (22%), Klebsiella species (14%), Escherichia coli (13%), Streptococcus species (10%) and Pseudomonas species (10%). In non-neutropenic patients, CoNS (29%), E. coli (11%), Pseudomonas species (8%), Streptococcus species (7%) and Klebsiella species (5%) were isolated. Twelve glycopeptide-resistant Enterococci (26% of total 47 Enterococcus species) were isolated. Four methicillin-resistant Staphylococcus aureus (14% of total 28 S. aureus) were isolated. Furthermore, 15 extended-spectrum β-lactamase producing Gram-negative bacilli were isolated. Among Gram-negative organisms, more than 91% isolates were sensitive to piperacillin/tazobactam, ceftazidime and ciprofloxacin and higher sensitivity rates (>95%) were recorded in gentamicin, polymyxin B and meropenem. Conclusion: This study highlights an ongoing trend towards Gram-positive organisms causing BSI in cancer patients. The antimicrobial regimens used in our institution are highly effective against commonly isolated organisms. The identification and the antimicrobial susceptibility of the microorganisms causing BSI in cancer patients remain important to develop antimicrobial treatment strategies including antimicrobial guidelines as well as infection control and to prevent the spread of antimicrobial resistance.

Blood culture contamination rates in two district general hospitals in the Southeast of England

Introduction: Blood culture is considered an important diagnostic tool to identify the causative agent of bloodstream infection (BSI) as well as to direct the definitive therapy. High contamination rate in any healthcare institution is directly linked with increased cost, use of unnecessary antibiotics and additional testing in the diagnostic laboratories. The audit team determined the blood culture contamination rate and the distribution of microorganisms causing BSIs in patients for the East Sussex Healthcare Trust, United Kingdom. Materials and Methods: This is a retrospective study which analyses the blood culture results over 2 years period (January 2014 to December 2015). Positive blood cultures were grouped into significant, contaminant or unknown significance by reviewing patient clinical data collected at the time of positive blood culture and the microbiology records. Results: A total of 11036 blood cultures were processed in the microbiology laboratory during the study (January 2014 to December 2015). A total of 1641 (14.9%) blood cultures were positive. Of 1641, 1298 (11.8%) and 286 (2.6%) were grouped as significant and contaminant, respectively. Fifty-six positive blood culture sets remained indeterminate due to the lack of the clinical information. The overall contamination rates in both hospitals in 2014 and 2015 were 0.9% and 1.7%, respectively. The average yearly contamination rate is 1.3%. Higher contamination rates were recorded from the paediatric, emergency, orthopaedics and surgical departments. A total of 1753 microorganisms were isolated. The most common isolated organisms include Escherichia coli 482, (27.5%), Coagulase-negative Staphylococcus, 274 (15.6%), Streptococcus species, 183 (10.4%), Staphylococcus aureus, 162 (9.2%), Klebsiella species, 135 (7.7%), Enterococcus species, 109 (6.2%) and Streptococcus pneumonia, 48 (2.7%). Thirty-three Candida species were isolated. The prevalence of methicillin-resistant S. aureus and the extended-spectrum b-lactamase producing Enterobacteriaceae were low. Conclusion: The present data showed lower contamination rate in the Trust than the acceptable rates. It also supports the need for regular training and education of healthcare professional that collect blood culture where the contamination rates are high.

Etiological agents isolated from blood in children with hemato-oncologic diseases (2002-2005)

Purpose: This study was performed to identify the etiologic agents and antimicrobial susceptibility patterns of organisms responsible for bloodstream infections in pediatric cancer patients for guidance in empiric antimicrobial therapy. Methods: One hundred and ninety-seven episodes of bloodstream infections that developed in 128 pediatric cancer patients were analyzed, which were identified at the Seoul National University Children's Hospital during a 4 year-period from 2002 to 2005. Results: A total of 214 pathogens was isolated, of which 64.0 percent were gram-negative, 31.3 percent were gram-positive bacteria, and 4.7 percent were fungi. The most common pathogens were Klebsiella spp. (21 percent) and Escherichia coli (16.8 percent), and coagulase-negative staphylococci (CNS, 7.9 percent) and viridans streptococci (7.5 percent) emerged as important pathogens. Neutro- penic patients were more often associated with gram-negative bacteria than non-neutropenic patients (67.5 percent vs. 51.1%, P=0.018) and patients with central venous catheters were more often asso- ciated with CNS and viridans streptococci than those without. Resistance rates of gram-positive bacteria to penicillin, oxacillin and vancomycin were 83.3 percent, 48.5 percent and 0.5 percent, respectively, and those of gram-negative bacteria to cefotaxime, piperacillin/tazobactam, imipenem, gentamicin and amikacin were 24.1 percent, 17.2 percent, 6.6 percent, 21.6 percent, and 14.2 percent, respectively. Gram-negative bacteremias were more often associated with intensive care than gram- positive bacteremias (26.5 percent vs. 10.3 percent, P=0.016), and patients with catheters were more often associated with intensive care (34.4 percent vs. 10.8 percent, P<0.001) and higher fatality rate (16.7 percent vs. 4.8 percent, P=0.012) than those without. Conclusion: This study revealed that gram-negative bacteria are still a dominant organism in bloodstream infections, especially in neutropenic patients, and confirmed that gram-positive bacteria are emerging as important etiological agents in bloodstream infections of pediatric hemato-oncologic patients. (Korean J Pediatr 2007;50:56-64)