Detection Of Bloodstream Infections Research Articles

Impact of a strategy based on unique blood culture sampling on contamination rate and detection of bloodstream infections in critically ill patients

BackgroundUnique blood culture (UBC) has been proposed to limit the number of venipuncture and to decrease the risk of BC contaminations (BCC) without affecting their yield. We hypothesized that a multi-faceted program based on UBC in the ICU may reduce the rate of contaminants with a similar performance for bloodstream infections (BSI) identification.MethodsIn a before and after design, we compared the proportion of BSI and BCC. A first 3-year period with multi-sampling (MS) strategy followed by a 4-month washout period, where staff received education and training for using UBC, and a 32-month period, where UBC was routinely used, while education and feedback were maintained. During the UBC period, a large volume of blood (40 mL) was sampled through a unique venipuncture with additional BC collections discouraged for 48 h.ResultsOf the 4,491 patients included (35% female patients, mean age 62 years) 17,466 BC were collected. The mean volume of blood per bottle collected increased from 2.8 ± 1.8 mL to 8.2 ± 3.9 mL between the MS and UBC periods, P < 0.01. A 59.6% reduction (95% CI 56.7–62.3; P < 0.001) of BC bottles collected per week was observed between the MS and UBC periods. The rate of BCC per patient decreased between the two periods from 11.2% to 3.8% (73.4% reduction; P < 0.001) for the MS and UBC periods, P < 0.001. Meanwhile, the rate of BSI per patient remained stable at 13.2% and 13.2% for the MS and UBC periods, P = 0.98.ConclusionsIn ICU patients, a strategy based on UBC reduces the contamination rate of cultures without affecting their yield.Graphical

200. The Utility of a Rapid Multiplex PCR Assay in the Management of Staphylococcus Aureus Bacteremia at a Tertiary Care Center

Abstract Background Staphylococcus aureus bacteremia (SAB) is a major cause of community and healthcare-acquired bacteremia and is associated with a high burden of morbidity and mortality. Appropriately tailoring management based on methicillin sensitivity can help minimize unnecessary administration of broad-spectrum antibiotics and ensure adequate treatment of MSSA/MRSA. The Verigene® (Luminex Corporation) is a multiplex PCR assay that provides rapid identification of bloodstream pathogens. We performed a QI project to determine the utility of this assay in managing patients with SAB. Methods We performed a single-center retrospective cohort study of positive SAB cultures from May 2020 to May 2021. Electronic health record review was conducted to abstract patient demographics, clinical characteristics, outcomes, blood culture data, and antibiotic management. Statistical analysis was done with the unpaired t-test and fishers exact test to identify associations of statistical significance. Results We identified 97 cases of SAB: 66% MSSA (n = 64), 34% MRSA (n = 33). Patient characteristics included: mean age 61 years, 58.8% male, 42% immunocompromised, 83.5% with ID consult, 38.1% with ICU admission, mean length of stay 20.3d, and 24.7% mortality. Using the Verigene® assay, we noted 2.6% discordance with standard microbiological technique (n = 2). The timing of Verigene® results and provider response were as follows: The mean duration of SAB was 3.1d (MSSA = 2.8d, MRSA = 3.6d, p = 0.2477). There was a statistically significant difference in patient mortality with respect to methicillin sensitivity status: MSSA 15.6%, MRSA 42.4%, p = 0.0075, as well as mortality with ID consult 19.8% versus no ID consult 50%, p = 0.0223. Conclusion Despite the incorporation of a rapid multiplex PCR assay to detect bloodstream infections, the time to de-escalation for MSSA was sub-optimal (2.7 days). ID consultation continues to be an important component of SAB management as it improves patient outcomes and contributes to education of healthcare providers. Disclosures Lan Duong, PharmD, Johnson &amp; Johnson: Stocks/Bonds|Lilly USA: Stocks/Bonds|Novavax: Stocks/Bonds Princy N. Kumar, MD, American Gene Technologies: Grant/Research Support|BioHaven: Grant/Research Support|Eli Lilly: Grant/Research Support|Gilead: Advisor/Consultant|Gilead: Grant/Research Support|Gilead: Stocks/Bonds|GSK: Grant/Research Support|GSK: Stocks/Bonds|Johnson&amp;Johnson: Advisor/Consultant|Johnson&amp;Johnson: Stocks/Bonds|Merck: Advisor/Consultant|Merck: Grant/Research Support|Merck: Stocks/Bonds|Moderna: Stocks/Bonds|Pfizer: Stocks/Bonds|Regeneron: Grant/Research Support|TheraTechnologies: Grant/Research Support|ViiV: Advisor/Consultant Joseph G. Timpone, Jr., MD, Gilead: Stocks/Bonds|Merck: Stocks/Bonds.

Effects of COVID-19 on Blood Culture Contamination at a Tertiary Care Academic Medical Center.

ABSTRACTThe COVID-19 pandemic has changed health care, from increased needs of personal protective equipment (PPE) to overloaded staff and influxes of patients. Blood cultures are frequently used to detect bloodstream infections in critically ill patients, but it is unknown whether the COVID-19 pandemic has had an impact on blood culture contamination rates. A total of 88,332 blood cultures taken over a 33-month period were analyzed to compare blood culture contamination rates before the COVID-19 pandemic to rates during the pandemic. A significant increase in the average number of monthly nurse-drawn and peripherally collected cultures occurred after the start of the pandemic, but there was a decrease in the average number of phlebotomy cultures. A significant increase in contamination rates (P < 0.001) was found in all nonemergency hospital departments during the COVID-19 pandemic, increasing from 2.1% to 2.5%. Increased rates during the COVID-19 pandemic were also found for nursing staff (2.0% to 2.4%) and both peripheral (2.1% to 2.5%) and indwelling line draws (1.1% to 1.7). The number of cultures drawn monthly increased in acute adult departments and both adult and pediatric emergency departments. Blood culture contamination rates in adult acute, adult emergency, and pediatric intensive care units increased after the start of the pandemic by 23%, 75%, and 59%, respectively. A positive correlation was found between blood culture contamination rates and COVID-19 incidence rates. Additional periodic staff training on proper blood collection technique and awareness of the workload of health care workers are recommended to decrease contamination rates during the COVID-19 pandemic.IMPORTANCE Understanding factors that contribute to blood culture contamination is important in order to take steps to limit contamination events. Here, we examine the effect the COVID-19 pandemic has had on blood culture contamination rates and specifically detail the effects based on the staff, draw types, and unit types. The conclusions provided here can be used as hospitals and laboratories navigate the COVID-19 pandemic or other times of high patient volume.

Healthcare-associated blood stream infections: An evaluation of blood culture as indicator

Background: A nosocomial infection or healthcare-associated illness that develops in patients after they are admitted to the hospital but was not present or incubating at the time of admission is referred to as a hospital acquired infection. In patients with severe viral and fungal infections today, it is one of the most prevalent and life-threatening consequences. Blood culture is one of the most important diagnostic tools for the diagnosis of hospital acquired infections. It can also help in providing a clinical as well as an etiological diagnosis. Aims and Objectives: The aim of the study is early detection of blood stream infections along with its antibiotic susceptibility pattern. Materials and Methods: All samples were obtained and processed using conventional microbiological techniques, and an antibiotic sensitivity test was carried out in accordance with CLSI recommendations. Results: Total 160 samples were processed, out of which 54 (34%) samples were positive. Out of 54 positive blood sample, maximum samples were from NICU (28) 52%, followed by causality (10) 18%, PICU (4) 7%, HDU (2) 3%, intensive careunit (4) 7%, surgery (6) 11%, and overall males contributed to higher positivity rate. Total nine different organisms were isolated, out of which Gram negative bacilli were comprised 40 (74%), Gram positive cocci 8 (14%) and Candida were 6 (11%). Among Gram-negative bacilli of most common species were Klebsiella pneumonia (30%), Acinetobacter baumanii (18%), Pseudomonas aeruginosa (11%), Burkhoderia cepacia (11%), and Serratia fonticola (3%). The most prevalent isolated species of gram-positive cocci were Staphylococcus aureus (11%), Coagulase negative S. aureus (3%), and Enterococcus faecalis (3%). Conclusion: This study on blood culture gives insight to magnitude of hospital acquired infections in our set up. Again result of antibiotic susceptibility tests gives overview of drug resistance problem at our set up. This may help in antibiotic stewardship program.

The importance of the criteria of systemic inflammatory Responce syndrome of early diagnostics and detection of bloodstream infections

The importance of the criteria of systemic inflammatory Responce syndrome of early diagnostics and detection of bloodstream infections

Early warning of bloodstream infection in elderly patients with circulating microparticles

BackgroundThe difficulty of early diagnosis of bloodstream infection in the elderly patients leads to high mortality. Therefore, it is essential to determine some new methods of early warning of bloodstream infection in the elderly patients for timely adjustment of treatment and improvement of prognosis.MethodsPatients aged over 65 years with suspected bloodstream infections were included and divided into bloodstream infection (BSI) and non-bloodstream infection (non-BSI) groups based on blood culture results. The morphology of microparticles (MPs) was observed by using transmission electron microscopy, and the number of MPs was dynamically monitored by flow cytometry.ResultsA total of 140 patients were included in the study: 54 in the BSI group and 86 in the non-BSI group. Total MPs (T-MPs) ≥ 6000 events/µL (OR, 7.693; 95% CI 2.944–20.103, P < 0.0001), neutrophil-derived MPs (NMPs) ≥ 500 events/µL (OR, 12.049; 95% CI 3.574–40.623, P < 0.0001), and monocyte counts ≤ 0.4 × 109/L (OR, 3.637; 95% CI 1.415–9.348, P = 0.007) within 6 h of fever were independently associated with bloodstream infection in the elderly patients. We also developed an early warning model for bloodstream infection in the elderly patients with an area under the curve of 0.884 (95% CI 0.826–0.942, P < 0.0001), sensitivity of 86.8%, specificity of 76.5%, positive predictive value of 70.8%, and negative predictive value of 89.8%.ConclusionThe early warning model of bloodstream infection based on circulating T-MPs, NMPs, and monocyte counts within 6 h of fever in the elderly patients was helpful in early detection of bloodstream infection and therefore promptly adjustment of treatment plan.

Bacteriologic Antibiography Outline of Isolates from Blood Culture at Tertiary Center

Bacteria found in blood circulation either consistently intermittently are commination to every organs of body. These infections can affect life and death. In India also blood stream infections are major causes of health problem that caused demise of patients in hospital. Timely diagnoses of infection with antimicrobial susceptibility assessment are important for optimization of treatment and best way to reduce hospital stay and improve patient health. In spite of recent advances in clinical diagnostics, blood culture remains the gold standard for the detection of blood stream infections. Studies in different places and regions have indicated the varying microbiological pattern of bloodstream infections which support the need for a continuous examination of the causative organisms. For the diagnosis of septicemia, Blood cultures are the “gold standard” are based on the detection of viable microorganisms in the blood. The main aim of this is to identify the bacteria causing bloodstream infections and to determine and analysis their antibiotic sensitivity pattern in a tertiary center. In this study blood for culture was collected from 940 clinically suspected cases of blood stream infection from the hospital. Collected blood samples were processed in the bacteriology section at microbiology laboratory and standard laboratory methods were used to identified isolates and then antibiotic susceptibility test was performed using CLSI guidelines. Total 940 blood samples were cultured in which 139(14.8%) were found positive. Among isolates, the most predominant organism was Staphylococcus aureus (51.8%) followed by Escherichia coli (24.5%) and the least was Salmonella species (1.4%), Proteus species (1.4%) and Acinetobacter species (1.4%). Among Gram positive isolates, Penicillin and Erythromycin showed high degree of resistance. Imipenem was particularly susceptible among the isolated. Gentamicin and Amikacin showed high in vitro susceptibility for both Enterobacteriaceae and Nonfermenters. This study provides information on bacteriological profile of septicemic isolates. Therefore continuous monitoring of the susceptibility of organisms towards antibiotics is necessary to prevent and spread of drug resistance.

A prospective study of epidemiology characteristics and outcomes of bloodstream infections in older patients.

This study aimed to investigate the characteristics of bloodstream infections (BSIs) in older patients and describe the differences between community-acquired, hospital-acquired and health care-associated BSIs. A prospective observational study was conducted at the University Hospital of Heraklion, Crete, Greece. Epidemiology, clinical characteristics and outcomes of BSIs were recorded. During a four-year period, 113 BSIs were recorded. Of them, 42% occurred in male patients; patients' mean age was 80years. BSIs were community-acquired in 76% of patients, hospital-acquired in 12% and health care-associated in 12%. The most commonly isolated bacteria were E coli and K pneumoniae. Thirty-day mortality from detection of BSIs was 27%. Patients with fever, without septic shock and with appropriate empirical treatment were less likely to die. Community-acquired, health care-associated and hospital-acquired BSIs had different presentation, microbiology and outcomes. Older patients had a high mortality. The absence of fever, inappropriate empirical treatment and septic shock were independent mortality predictors.

Bloodstream Bacterial Infection in Neutropenic Acute Leukemia Patients

Objective: The rapid detection of blood stream infection has the potential to not only improve patient outcomes due to quicker administration of appropriate antibiotics but also improve antibiotic stewardship by reducing patient exposures to ineffective or unnecessary broad-spectrum antibiotics. Methods: In this study blood samples from acute leukemia neutropenic patients (samples under study) and non neutropenic patients (control) were tested using cultural and non-cultural based techniques via blood culture, C-reactive protein (CRP), Erythrocyte sedimentation rate (ESR) and Molecular techniques (bacterial 16S rDNA analysis). Results: About 22% & 15% were shown positive in blood culturing; 94% & 85% were positive for CRP; 86% and 75% were presented by elevation in ESR rate for the first hour; 94% and 80% were presented by elevation in ESR rate for second hour. Treatment response of the positive cases by blood culture only was found to be 72.7% and 100% not in remission for samples under study and control respectively. In cases under study there is statistically significant correlation between culture growth sensitivity and PCR technique with P value 0.005.

Droplet digital polymerase chain reaction for rapid broad-spectrum detection of bloodstream infections.

SummaryThe droplet digital polymerase chain reaction (ddPCR) is a novel molecular technique that allows rapid quantification of rare target DNA sequences. Aim of this study was to explore the feasibility of the ddPCR technique to detect pathogen DNA in whole blood and to assess the diagnostic accuracy of ddPCR to detect bloodstream infections (BSIs), benchmarked against blood cultures. Broad‐range primers and probes were designed to detect bacterial 16S rRNA (and Gram stain for differentiation) and fungal 28S rRNA. To determine the detection limit of ddPCR, 10‐fold serial dilutions of E. coli and C. albicans were spiked in both PBS and whole blood. The diagnostic accuracy of ddPCR was tested in historically collected frozen blood samples from adult patients suspected of a BSI and compared with blood cultures. Analyses were independently performed by two research analysts. Outcomes included sensitivity and specificity of ddPCR. Within 4 h, blood samples were drawn, and DNA was isolated and analysed. The ddPCR detection limit was approximately 1–2 bacteria or fungi per ddPCR reaction. In total, 45 blood samples were collected from patients, of which 15 (33%) presented with positive blood cultures. The overall sensitivity of ddPCR was 80% (95% CI 52–96) and specificity 87% (95% CI 69–96). In conclusion, the ddPCR technique has considerable potential and is able to detect very low amounts of pathogen DNA in whole blood within 4 h. Currently, ddPCR has a reasonable sensitivity and specificity, but requires further optimization to make it more useful for clinical practice.

T2Bacteria Panel can rapidly and accurately detect bloodstream infections

Use of the T2Bacteria Panel, a molecular rapid diagnostic test (mRDT), resulted in 90% sensitivity and specificity in identifying five common bacterial pathogens for proven bloodstream infections: Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Escherichia coli, according to a recent study published in Annals of Internal Medicine.1.Nguyen M.H. et al.Ann Intern Med. 2019; 170: 845-852Google Scholar These findings have implications for health-system clinicians, including pharmacists. Blood cultures are the gold standard for diagnosing bloodstream infections, but results often take too long for patients who need early interventions (such as those with sepsis). The T2Bacteria Panel quickly identifies select pathogens directly from whole blood samples without the need for cultures. “The main advantage of the T2Bacteria Panel is the ability to detect these targeted bacteria directly from whole blood samples in a couple of hours as opposed to a couple of days with conventional microbiology cultures,” noted Elias B. Chahine, PharmD, FCCP, FFSHP, BCPS, BCIDP, professor of pharmacy practice at Gregory School of Pharmacy, Palm Beach Atlantic University. “This advantage may translate into a more rapid initiation of an appropriate antibiotic regimen or a more rapid switch to an appropriate antibiotic regimen.” Researchers conducted a diagnostic accuracy study to compare the performance of the T2Bacteria Panel with that of a single set of blood cultures in diagnosing proven, probable, and possible bloodstream infections caused by T2Bacteria-targeted organisms (i.e., E. faecium, S. aureus, K. pneumoniae, P. aeruginosa, and E. coli).1.Nguyen M.H. et al.Ann Intern Med. 2019; 170: 845-852Google Scholar The study included data from 1,427 patients for whom blood cultures were ordered. Testing yielded 39 positive blood cultures (3%) and 181 positive results for the T2Bacteria Panel (13%). Of the 39 positive blood cultures, 35 were positive per the T2Bacteria Panel results, and 4 were negative. The rate of negative blood cultures with a positive T2Bacteria Panel result was 10% (146 of 1,427). The researchers noted that blood culture and T2Bacteria Panel results were concordant in 90% of the samples and discordant in 10%. The mean times from start of blood culture incubation to positivity and species identification were 38.5 hours and 71.7 hours, respectively, whereas the mean times to species identification were much shorter with the T2Bacteria Panel: 3.61 to 7.70 hours depending on the number of samples tested. In their 2016 guidelines for implementing an antibiotic stewardship program, the Infectious Diseases Society of America (IDSA) and the Society for Healthcare Epidemiology of America (SHEA) recommend the use of mRDTs in addition to conventional microbiology cultures and routine reporting on blood specimens only if combined with an active antibiotic stewardship program.2.Barlam T.F. et al.Clin Infect Dis. 2016; 62: e51-e77Crossref PubMed Scopus (1171) Google Scholar The IDSA/SHEA guidelines note that this is a weak recommendation supported by moderate-quality evidence. To maximize cost-effectiveness, institutions should carefully select a mRDT platform based on the needs of their patient populations and on local resistance patterns, Chahine said. He noted that the main disadvantage of the T2Bacteria Panel compared with other available mRDTs is its inability to detect other organisms beyond the five targeted bacteria. Another disadvantage of mRDTs is their inability to provide information on the pathogens’ susceptibilities to antimicrobials. Chahine also said that integration of an mRDT into an antibiotic stewardship program should be accompanied by a checklist before, during, and after implementation and should involve infectious diseases physicians, pharmacists, and microbiologists. A well-trained infectious diseases physician or pharmacist should be available to act on the results as soon as they become available. Most but not all positive experiences of using mRDTs come from large academic medical centers with robust antibiotic stewardship programs. As more outcome data emerge on mRDTs, clinicians will become more comfortable justifying their costs and using them in clinical practice.

Rapid Diagnosis of Blood Stream Infections in ICU: Recent Advances

Blood stream infections and sepsis are major causes of hospitalization in most intensive care units around the globe, especially in developing countries like Nepal. Although the sepsis guidelines emphasize the role of early institution of appropriate antibiotics, it is practically challenging due to delayed turnover time of currently available diagnostic tests. Modifications in traditional blood culture methods, use of molecular techniques and availability of biomarkers have raised hope in rapid detection of blood stream infections.

The correlation between nursing workload and bloodstream infection from central venous catheter in ICU

Introduction: Bloodstream infection associated with the presence of central venous catheters is the second most common hospital infection in the Intensive Care Unit (ICU). The nursing stuff is an essential part of the human resources of the ICU which contributes substantially to provide holistic and effective care to critically ill patients. The level of the nursing workload and its possible influence on the clinical course and outcome of critically ill ICU patients has been systematically studied in recent years. Mainly, was studied the connection with the care quality indicators such as mortality and infections Aim: The purpose of this study was to estimate the nursing workload in the ICU and to investigate the impact of bloodstream infection from Central Venous Catheter (CLABSI). Methods: The study sample consisted of 39 patients who were hospitalized in a multidisciplinary ICU in a 3 month period. For the detection of bloodstream infections we used the surveillance definition of CDC/NHSN for in vitro confirmed bloodstream infection (CLABSI). Measurement of nursing workload was via the NAS scale and the calculation was performed for each patient once existed or entering the ICU from baseline and constantly on a daily basis. A comparison of the quantitative variables was done with the statistical criterion Pearson’s x 2 , to compare the bisectors qualitative variables selected quantitative variables was used the t-test analysis and MannWhitney test. Results: Of the total sample, 74,4% (n = 29) were male, with a mean age 59 ± 21 years. The duration of ICU stay was 24 ± 23 days and mortality was 41%. The duration of hospitalization was 28 ± 24 days and the corresponding mortality of 46.2%. All correlations presented no statistically significant difference than the first day’s NAS in which appears the biggest difference between the values (p=0,046) but the NAS of the patients who did not develop bacteremia be more increased over those experienced. Conclusions: The nursing workload in our study did not prove as a risk factor for the occurrence of bloodstream infection in the ICU.

Best Practices for Detection of Bloodstream Infection.

Each year in the US and Europe, an estimated 750000 and 1200000 patients, respectively, develop a bloodstream infection (BSI) with a bacterial or fungal pathogen (1, 2). Given the high mortality associated with sepsis, detection of BSIs is one of the most important functions of the clinical microbiology laboratory. A delay in therapy for a BSI is independently associated with worse outcomes (1, 2). In the setting of BSI, it is essential to establish the etiology of infection and the antimicrobial resistance profile of the infecting agent to optimize antimicrobial therapy. Given the clinical …

Accurate prediction of blood culture outcome in the intensive care unit using long short-term memory neural networks.

Blood cultures are often performed in the intensive care unit (ICU) to detect bloodstream infections and identify pathogen type, further guiding treatment. Early detection is essential, as a bloodstream infection can give cause to sepsis, a severe immune response associated with an increased risk of organ failure and death. The early clinical detection of a bloodstream infection is challenging but rapid targeted treatment, within the first place antimicrobials, substantially increases survival chances. As blood cultures require time to incubate, early clinical detection using physiological signals combined with indicative lab values is pivotal. In this work, a novel method is constructed and explored for the potential prediction of the outcome of a blood culture test. The approach is based on a temporal computational model which uses nine clinical parameters measured over time. We use a bidirectional long short-term memory neural network, a type of recurrent neural network well suited for tasks where the time lag between a predictive event and outcome is unknown. Evaluation is performed using a novel high-quality database consisting of 2177 ICU admissions at the Ghent University Hospital located in Belgium. The network achieves, on average, an area under the receiver operating characteristic curve of 0.99 and an area under the precision-recall curve of 0.82. In addition, our results show that predicting several hours upfront is possible with only a small decrease in predictive power. In this setting, it outperforms traditional non-temporal, machine learning models. Our proposed computational model accurately predicts the outcome of blood culture tests using nine clinical parameters. Moreover, it can be used in the ICU as an early warning system to detect patients at risk of blood stream infection.

Rapid detection of carbapenemases directly from positive blood cultures by the β-CARBA test.

The rapid detection of blood stream infections (BSI) by carbapenemase-producing Enterobacterales (CPE) is indispensable to early optimize antibiotic treatment and to improve survival. While phenotypic tests are time-consuming and PCR is expensive and not available in many routine laboratories, colorimetric tests (e.g., Carba NP test) can provide rapid results at moderate cost. However, up to now, the detection of CPE-BSI requires a further 3-h incubation in broth supplemented with zinc sulfate and imipenem after a blood culture has become positive, thereby causing delay and additional hands-on time. The purpose of this study was to develop and evaluate a new method for the detection of CPE directly from positive blood culture without the need for incubation in broth, based on the commercially available colorimetric β-CARBA test. For the evaluation, blood cultures spiked with 140 different Enterobacterales isolates producing diverse beta-lactamases were tested with the new method. Of these, 70 were CPE (OXA-48-like, NDM, KPC, VIM, and GIM). After blood cultures turned positive, blood culture fluid was drawn, and erythrocytes were hemolyzed with SDS, washed, and equilibrated before the β-CARBA was performed on the bacterial pellet. All carbapenemases were reliably detected, including weak carbapenemases of the OXA-48 group. The sensitivity was 100% (95% CI 94.9-100) and the specificity 94.3% (95% CI 89.2-99.4). The time to result was 20 to 45min. Carbapenemases can rapidly and reliably be detected directly from blood cultures using the new method, which could help to improve the outcome of these difficult-to-treat infections.

Microbial Infections in Immunodeficient Children in Qena University Hospital with Special Reference to DNA Damage in Peripheral Blood Leucocytes

Background: Immunodeficiency disorders involve malfunction of the immune system,resulting in infections that develop and recur more frequently, are more severe, and last longerthan usual, Impair the immune system's ability to defend the body against foreign or abnormalcells that invade or attack it (such as bacteria, viruses, fungi, and cancer cells). As a result,unusual bacterial, viral, or fungal infections or lymphomas or other cancers may develop.Patients and methods: A study to detect blood stream infections was done using 100 bloodcultures obtained from 100 immunocompromised children.Results and conclusions: The most commonly isolated are bacterial organism (40 %)the mostcommon bacterial isolates are klebsiella species (17 | 40 ,42.5%). Estimation of DNA damagewas done for 40 patients and 10 apparently healthy children as control subjects. The DNAdamage was detected has took the smear shape on gel electrophoresis. This was found in (12|40,30%), (P value < 0.001) with significant difference.

A retrospective evaluation of the performance of 2 blood culture media in detection of bloodstream infection: clinical comparison of BACTEC and BacT/Alert systems

Objective To evaluate the clinical performance of the BACTEC Plus aerobic, BACTEC Lytic anaerobic, BacT/Alert aerobic and anaerobic blood culture media in detection of bloodstream infections. Methods Retrospective study was conducted. A total of four blood culture bottles from each inpatient with suspected bloodstream infections were collected and analyzed from June 2013 to September 2015 in Peking University People′s Hospital. The four bottles, including BACTEC Plus aerobic, BACTEC Lytic anaerobic, BacT/Alert FA aerobic and BacT/Alert FN anaerobic media, and was incubated for 5 days in the BacT/Alert 3D and BACTEC FX instruments, respectively. Time to detection (TTD) and positive rate in detecting bacteria of the two systems were evaluated by Wilcoxon test and Chi-square test. Results Among 2 189 total cultures collected, 20 were excluded because of blood shortage and 201 (9.27%) were positive for pathogens. The positive rates of BACTEC Plus aerobic media and BacT/Alert FA aerobic media were 75.3% (140/186) and 69.4% (129/186) (χ2=1.625, P=0.202), respectively. While, the positive rates of BacT/Alert FN anaerobic media and BACTEC Lytic anaerobic media were 81.8% (99/121) and 63.6% (77/121) for total organisms, respectively (χ2=10.083, P=0.001). A significant difference in TTD was detected in BACTEC Plus aerobic media[11.0 (8.0-16.0) h]and BacT/Alert FA aerobic media[13.9 (10.4-18.7) h](Z=-5.240, P<0.001). BACTEC Lytic anaerobic media[8.0 (7.0-10.0) h]had a shorter TTD (Z=-4.299, P<0.001) than BacT/Alert FN anaerobic media[11.3 (9.3-12.7) h]. The positive rates of BACTEC and BacT/Alert system were 74.13% (149/201) and 74.63% (150/201), respectively, compared with taking one set from each system. Conclusions BACTEC media has a shorter TTD and almost the same bacterial recovery, and lower false positive rate than the BacT/Alert media.(Chin J Lab Med, 2017, 40: 303-308) Key words: Bacteremia; Blood culture; Bacteria; Culture medias; Evaluation studies

Establishment and evaluation of mouse models of Staphylococcus aureus and Klebsiella pneumoniae bloodstream infections

Objective To establish the reliable models for early diagnosis of bloodstream infections by common clinical bacteria and to provide reliable experimental models for screening and validation of biomarkers in the early stage of bacterial bloodstream infections. Methods Strains of Staphylococcus aureus (S.aureus) ATCC25923 and Klebsiella pneumoniae (K.pneumoniae) ATCC700603 were used as experimental strains. Different concentrations of bacterial suspensions were injected into mice through tail vein. LD50 (median lethal dose) was calculated by Karber method and the concentration of 1/2LD50 was used for injection. The established mouse models were evaluated based on the changes in physical signs, body weights, white blood cells (WBC), platelets and IL-6 as well as the results of blood culture, PCR and HE staining. Results LD50 of S. aureus and K. pneumoniae to ICR mice were 8.1×108 CFU/ml and 1.11×109 CFU/ml, respectively. Body weights of mice decreased significantly at the time point of 24 h after infection. WBC counts in normal mice were about (1.42±0.66)×109/L, but increased in model groups at 3 h after bacteria challenge. Compared with the control group, WBC counts in model groups increased significantly at 6 h (P<0.05), followed by decreases. Two days after infection, WBC counts in model groups increased again and remained at high levels till the 7th day. However, PLT counts in the model groups dropped dramatically within 2 days as compared with that in control group (P<0.05). Increase of IL-6 was detected in the early K. pneumoniae infection and the extent of that was larger than that in S. aureus infection. Results of the whole blood culture were all positive within 2 days after infection. PCR analysis confirmed that the bloodstream infection pathogens were S. aureus and K. pneumoniae. Alveolar exudation, edema and leukocyte infiltration were observed in lung and liver tissues with HE staining. Conclusion The mouse models of S. aureus and K. pneumoniae infections for early detection of bloodstream infections are successfully established. This study provides reliable animal models for further researches on early diagnosis of different pathogen-induced bloodstream infections. Key words: Staphylococcus aureus; Klebsiella pneumonia; Virulence factor; Bloodstream infection model

Changes in plasma protein levels as an early indication of a bloodstream infection.

Blood culture is the primary diagnostic test performed in a suspicion of bloodstream infection to detect the presence of microorganisms and direct the treatment. However, blood culture is slow and time consuming method to detect blood stream infections or separate septic and/or bacteremic patients from others with less serious febrile disease. Plasma proteomics, despite its challenges, remains an important source for early biomarkers for systemic diseases and might show changes before direct evidence from bacteria can be obtained. We have performed a plasma proteomic analysis, simultaneously at the time of blood culture sampling from ten blood culture positive and ten blood culture negative patients, and quantified 172 proteins with two or more unique peptides. Principal components analysis, Orthogonal Projections to Latent Structures Discriminant Analysis (OPLS-DA) and ROC curve analysis were performed to select protein(s) features which can classify the two groups of samples. We propose a number of candidates which qualify as potential biomarkers to select the blood culture positive cases from negative ones. Pathway analysis by two methods revealed complement activation, phagocytosis pathway and alterations in lipid metabolism as enriched pathways which are relevant for the condition. Data are available via ProteomeXchange with identifier PXD005022.