Significance Of Blood Cultures Research Articles

Significance of Blood Culture in Immuno Compromised Paediatric Patients for Isolation of Unusual Non -Fastidious Pathogens

Significance of Blood Culture in Immuno Compromised Paediatric Patients for Isolation of Unusual Non -Fastidious Pathogens

Significance of blood cultures in nursing home-acquired pneumonia.

The significance of blood cultures in nursing home-acquired pneumonia (NHAP) is incompletely understood. We retrospectively analyzed the clinical and laboratory features of 515 patients with NHAP admitted to our hospital over an 11-year period. Blood cultures were obtained from 336 patients (65.2%). We compared 13 and 323 patients with positive and negative blood cultures, respectively. The former showed lower systolic blood pressure and higher blood urea nitrogen (BUN), creatinine, C-reactive protein (CRP), and A-DROP scores than the latter. With regard to A-DROP parameters, patients with positive blood cultures showed significantly higher rates of dehydration (BUN≥21mg/dL) and low blood pressure (systolic blood pressure≤90mmHg). Multivariate analysis identified CRP values and low blood pressure as independent predictors of bacteremia: CRP (odds ratio [OR] 1.11; 95% confidence interval [CI] 1.04-1.19, P=0.003) and low blood pressure (OR 6.03; 95% CI 1.06-34.25, P=0.04). A receiver operating characteristic curve indicated that CRP was of moderate accuracy (area under the curve=0.75), and its diagnostic accuracy was optimal at a cut-off point of 19.2mg/dL (sensitivity 69%, specificity 87%). Since the probability of true bacteremia is very low in NHAP, obtaining blood cultures from all patients with NHAP is unnecessary. However, our results suggest blood cultures are warranted from patients with high CRP values (≥20mg/dL) or low blood pressure.

National Glycopeptide-Resistant Enterococcal Bacteraemia Surveillance Working Group Report to the Department of Health — August 2004

<h2>Summary</h2> <ul><li>1.From September 2003, acute National Health Service trusts in England have been required by the Department of Health to undertake mandatory surveillance of bacteraemias caused by glycopeptide-resistant enterococci (GRE).</li><li>2.In total, 4855 enterococcal bacteraemias (including 256 reports of ‘Group D streptococci') were reported through the voluntary reporting system to the Communicable Disease Surveillance Centre (CDSC) in England and Wales in 2002, and 8.9% of the reports that contained information on vancomycin susceptibility indicated that the isolate was resistant to vancomycin. Most hospitals reported fewer than five GRE bacteraemias per year to the CDSC, with only 13 hospitals reporting more than five episodes per year, although there is undoubtedly an element of under-reporting.</li><li>3.This Working Group was established to review the methods used to identify and test the susceptibility of enterococci to glycopeptides, and to make recommendations on the reporting of GRE bacteraemias, as there were indications that current methods would not provide a suitable basis for this surveillance.</li><li>4.A review of methods was undertaken, including a national questionnaire on methods, approaches to testing and risk factors for GRE bacteraemia. This, together with data from routine laboratory reports and special surveys, revealed the following.<li>–A significant proportion of enterococci are not identified to species level.</li><li>–There are problems with identification of enterococci. Commercially available kits do not identify some enterococcal species reliably.</li><li>–Not all laboratories test vancomycin susceptibility of enterococci from bacteraemia. This does not allow a robust assessment of GRE bacteraemia rates because the prevalence of glycopeptide resistance will be underestimated if laboratories test teicoplanin alone or no glycopeptides against enterococci.</li><li>–There are technical difficulties in detecting non-VanA resistance in enterococci and this will also contribute to under-reporting of glycopeptide resistance.</li></li><li>5.Clinically significant GRE infection is associated with a worse prognosis than infection with susceptible strains, but this factor has not been clearly separated from the possible influence of co-morbidities and antibiotic usage.</li><li>6.GRE bacteraemia occurs mainly on specialist units, particularly transplantation, renal, haematological malignancy and intensive care units. Hospitals with such units will inevitably have a higher risk of featuring prominently in surveillance studies. Hence, meaningful denominators for surveillance of GRE bacteraemia are required.</li></ul> <h3>Recommendations for GRE bacteraemia surveillance</h3> <ul><li>1.As the mandatory surveillance of glycopeptide-resistant enterococci (GRE) bacteraemias has already started, this report recommends a phased approach to some of the developments, such as using meaningful denominators for the bacteraemia rates.</li><li>2.Rates of GRE bacteraemias in trusts should not be used as a performance indicator because the numbers are too small for valid analysis in this way.</li><li>3.GRE bacteraemias as a proportion of all clinically significant bacteraemias in the trust should be measured as an indicator of changing trends.</li><li>4.Since most GRE are likely to be associated with specialist units, reports of GRE bacteraemia should indicate the specialty in which the patient acquired the infection.</li><li>5.Data on clinical activity in the special units where patients acquired GRE bacteraemias should be obtained from trusts with more than five GRE bacteraemias in a year.</li><li>6.The significance of blood cultures containing GRE should be assessed clinically. If the bacteraemia that includes GRE is deemed to be clinically significant (according to the case definitions for bacteraemia), whether mono- or polymicrobial, it should be reported as a GRE bacteraemia.</li><li>7.Enterococci from blood cultures should be identified to species level to provide data on resistance rates in different species.</li><li>8.Biochemical identification should be augmented by antimicrobial susceptibility patterns. The identification is suspect if Enterococcus faecalis appears to be ampicillin resistant and/or quinupristin/dalfopristin susceptible, or if Enterococcus faecium appears to be ampicillin susceptible and/or quinupristin/dalfopristin resistant. The identification and susceptibility of such isolates should be checked and, if confirmed, the isolate should be sent to a reference laboratory for further investigation.</li><li>9.Enterococci from blood cultures should be tested for susceptibility to vancomycin. Teicoplanin is not an acceptable alternative to vancomycin for these purposes.</li><li>10.Standardized methods should be used for glycopeptide susceptibility testing of enterococci, and the technical requirements of the methods must be adhered to.</li><li>11.The situation should be reviewed after a year and the methodology should be amended as appropriate.</li></ul> <h3>Recommendations for further research</h3> <ul><li>1.A group should be established to explore methods of data collection for global and individual risk factors for GRE bacteraemia.</li><li>2.Further studies on the performance of commercial identification kits with a range of enterococcal species are necessary.</li><li>3.Further studies to improve the reliability of susceptibility testing methods for detection of GRE are necessary.</li></ul>

Incidence and Clinical Significance of Positive Blood Cultures in Febrile Episodes of Patients with Hematological Malignancies

The characteristics of 554 febrile episodes in 126 patients with a hematological malignancy over a 6-year period (1985-90) were reviewed in order to study the current incidence and clinical significance of blood culture positivity. An infection was documented microbiologically in 28% and clinically in 30% of the episodes. Blood cultures were positive in 19% of the febrile episodes. The rate of blood culture positivity was unrelated to the type of hematological malignancy, to neutropenia and to the presence of infection foci. 21% (26/126) of the patients died of sepsis-related causes. Sepsis-related death occurred in 23% of the blood culture positive febrile episodes, with a median survival time of 2 days. Infection prophylaxis did not reduce either the rate of blood culture positivity or the rate of sepsis-related deaths. Thus, the small proportion of febrile episodes whose fever etiology could be established by blood culture represented 'the tip of the iceberg', i.e. rapidly lethal septic infections with a high mortality rate. This fatality could neither be predicted by a search for infection foci nor prevented by infection prophylaxis.

The significance of blood cultures in the newborn period.

Septicema during the newborn period often occurs with deceptively benign early clinical manifestations. 1 Consequently, the clinician is forced to initiate vigorous antibiotic treatment on suspicion and thus depend upon a single pretreatment culture of the blood for a positive bacteriological diagnosis. It is important, therefore, to examine the validity of information gained from single cultures of the blood in newborn infants. As septicemia during the neonatal period is still a significant pediatric problem, it seemed important to investigate the interpretation of blood cultures at this age. Clinical Material and Methods Consecutive normal infants born over a three-month period at Ancker General Hospital, St. Paul, were studied. The infants had no physical abnormalities, no evidence of skin lesions or infection, and no temperature elevation. Dry skin care was practiced during this period of time. All blood for the cultures was drawn by one of us. Skin over the neck was