Selective use of blood cultures in emergency department pneumonia patients

Our objectives were to identify factors associated with positive blood cultures and to evaluate blood culture use in the management of hospitalized pneumonia patients to limit their use. A retrospective chart review was conducted at a community teaching hospital. Emergency Department patients with an admission diagnosis of pneumonia during calendar years 2001-2002 were included. Patients younger than age 18 years and those with a non-pneumonia discharge diagnosis were excluded. Of 684 eligible patients, 23 (3.4%) had true positive blood cultures. All organisms were sensitive to empiric antibiotics. Three risk factors were associated with positive blood cultures: oxygen saturation < 90%, serum sodium < 130 and respiratory rate > 30 breaths/min. No patient had antibiotic coverage broadened based on blood culture results. Positive blood culture rates were low and did not affect the clinical management of pneumonia patients. We recommend eliminating blood cultures in community-acquired pneumonia (CAP) patients, but obtaining blood cultures in patients at risk for multi-drug resistant pathogens, such as health-care-associated pneumonia (HCAP) patients.     

Utility of follow-up blood cultures for Gram-negative rod bacteremia in children

Persistent Gram-negative rod (GNR) bacteremia is uncommon under appropriate antibiotic therapy. A recent study showed that follow-up blood cultures (FUBCs) to confirm clearance 24–48 h after initiation of antibiotics, added little value in the management of GNR bacteremia in adults. However, the utility of FUBC in children is still unknown. We retrospectively reviewed the microbiology database to identify children aged <18 years with GNR bacteremia. Clinical information including gender, age, underlying diseases, presence of central venous line (CVC), source of bacteremia, and organisms was extracted from medical records. FUBCs for 99 episodes of GNR bacteremia in children became positive in 21%, which led to intervention in 57% of the episodes. In multivariate analysis between FUBC positive (n = 21) and negative (n = 78) groups, presence of CVC (n = 18, 86% vs n = 38, 49%, P = 0.001) and resistance to empirical antibiotics (n = 3, 14% vs n = 4, 5%, P = 0.04) were independently associated with positive FUBCs. Interestingly, no positive FUBC was observed in cases due to UTI (n = 13). Contrary to findings in adults, FUBC may still be useful in the management of GNR bacteremia in children.     

Occult bloodstream infections in adults: a “benign” entity

Background

Patients with septic episodes whose blood cultures turn positive after being sent home from emergency departments (EDs) are recognized as having occult bloodstream infections (BSI). The incidence, etiology, clinical circumstances, and outcome of occult BSI in children are well known, but, to our knowledge, data in adult patients are scarce. We analyzed the episodes of occult BSI in adult patients at our institution.

Methods

This is a retrospective cohort study (September 2010 to September 2012), in adult patients discharged from the ED in whom blood cultures turned positive. Patients were evaluated according to a preestablished protocol.

Results

We recorded 4025 cases of significant BSI in the ED and 113 patients with adult occult BSI. In other words, the incidence of occult BSI in the ED was 2.8 per 100 episodes. The predominant microorganisms were gram-negative bacteria (57%); Escherichia coli was the most common (41%), followed by gram-positive bacteria (29%), anaerobes (6.9%), polymicrobial (6.1%), and yeasts (0.8%). The most frequent suspected origin was urinary tract infection (53%), and most infections were community acquired (63.7%). Of the 105 patients that we were able to trace, 54 (42.5%) were asymptomatic and were receiving adequate antibiotic treatment at the time of the call, and 65 (51.2%) had persistent fever or were not receiving adequate antibiotic treatment.

Conclusions

Occult BSI is relatively common in patients in the adult ED. Despite the need for readmission of a fairly high proportion of patients, occult BSI behaves as a relatively benign entity.     

Adjustment of antibiotic treatment according to the results of blood cultures leads to decreased antibiotic use and costs

INTRODUCTION: To avoid the use of unnecessary broad-spectrum antibiotics, empirical therapy of bacteraemia should be adjusted according to the results of blood cultures. OBJECTIVES: To investigate whether the results of blood cultures led to changes in antibiotic use and costs in a tertiary-care university hospital in Norway. METHODS: Medical records from all patients with positive blood cultures in 2001 were analysed retrospectively. Factors predisposing to infections, results of blood cultures, antibiotic use and outcome were recorded. The influence of blood culture results on antibiotic treatment and costs were analysed. RESULTS: The antibiotic use in 226 episodes of bacteraemia in 214 patients was analysed. According to the guidelines empirical antibiotic treatment should be adjusted in 166 episodes. Antibiotic use was adjusted in 146 (88%) of these 166 episodes, which led to a narrowing of therapy in 118 (80%) episodes. Compared with empirical therapy there was a 22% reduction in the number of antibiotics. Adjustment of therapy was more often performed in Gram-negative bacteraemia and polymicrobial cultures than in Gram-positive bacteraemia. In bacteraemia caused by ampicillin-resistant Escherichia coli, ampicillin was mostly replaced by ciprofloxacin. The cost for 7 days adjusted therapy in 146 episodes was euro19,800 (23%) less than for 7 days of empirical therapy. CONCLUSIONS: Adjustment of antibiotic therapy according to the results of blood cultures led to a reduction in the number of antibiotics and a narrowing of antibiotic therapy. The costs for antibiotics decreased.     

Usefulness of initial blood cultures in patients admitted with pneumonia from an emergency department in Japan

Guidelines recommend obtaining blood cultures for all patients admitted with pneumonia. However, recent American studies have reported the low impact of these cultures on antibiotic therapy. Our aim was to investigate the incidence of bacteremia and change of therapy in admitted pneumonia patients from whom blood cultures were obtained in the emergency department (ED). A retrospective, observational, cohort study was conducted on consecutive patients (age ≥12 years) with pneumonia hospitalized through the ED between January 1 and December 31, 2006, in an urban teaching hospital in Japan. Data were collected on antibiotic sensitivities, empirical antibiotics, and changes of antibiotic management. Blood cultures were classified as positive, negative, or contaminant, based on previously established criteria. Out of 164 consecutive cases, blood cultures were positive in 6 patients (3.7%; 95% confidence interval [CI], 0.8%–6.6%), contaminated in 6 (3.7%), and negative in 152 (92.7%). Of the 6 bacteremic patients, 2 cases were likely to have been caused by concomitant diseases. Blood culture results altered therapy for 4 patients (2.4% of 164; 95% CI, 0.7%–6.1%), of whom 2 patients (1.2%; 95% CI, 0.1%–4.3%) had their coverage narrowed, 1 patient (0.6%; 95% CI, 0.0%–3.4%) had coverage broadened, and 1 patient had altered therapy before the drug sensitivities were reported. Considering cost and workload, the overall total annual cost was €758 631 (€107 = 1 $US in June 2008). Blood cultures could identify organisms in only a few patients with pneumonia and rarely altered antibiotic management even in patients with positive cultures. It may not be necessary to obtain blood cultures for patients admitted with pneumonia.     

Utility of peripheral blood cultures in patients with cancer and suspected blood stream infections: a systematic review

Purpose

The utility of peripheral blood cultures in patients with cancer and/or hematopoietic stem cell transplantation (HSCT) recipients with central venous lines (CVL) and suspected blood stream infection (BSI) is controversial. Our main objective was to describe the proportion of bacteremia detected only by the peripheral blood (PB) culture in order to define its role in the evaluation of patients in this setting.

Methods

We performed electronic searches of OVID Medline, EMBASE, and the Cochrane Central Register of Controlled Trials for studies of adults or children with cancer and/or HSCT that evaluated concurrent PB and CVL cultures and reported sufficient data to permit calculation of the primary outcome. The proportion of bacteremia identified by site of sample was used as the effect measure. The review was registered in PROSPERO: CRD42011001610.

Results

From 149 reviewed articles, 7 were included in the meta-analysis. In a total number of 10,370 paired blood cultures, bacteremia was detected in 17?%. Thirteen percent of BSI were only identified by PB, while 28?% of infections were only identified by CVL.

Conclusions

PB cultures identified many episodes of bacteremia not detected in the CVL culture. This finding suggests that PB culture should be considered in the evaluation of patients with cancer and/or HSCT with suspected BSI.     

The 24-h reporting of Gram stains from positive blood cultures contributes to physician's use of appropriate antimicrobials: Experience at a university hospital

Although recent technological advances for the diagnosis of bloodstream infection (BSI) provide rapid and accurate results, blood culture maintains a key role in the diagnosis of BSI. The objective of this study was to determine whether 24-h reporting by telephone to disclose the suspected microorganism based on the Gram stain morphology from positive blood cultures (first laboratory report) affects a physician's use of appropriate antimicrobials. A total of 627 (14%) out of 4413 blood samples, excluding duplicate samples from the same patient on the same day, were positive for blood cultures between January and December 2016. The contamination rate of blood cultures during the study period was 2.3%. Among 627 patients with positive blood cultures, 538 (86%) were receiving antibiotics at the time of the first laboratory report, of which 502 (80%) thereafter continued the same antimicrobials, and the remaining 36 (6%) were changed to appropriate antimicrobials after the first laboratory report. An additional 25 (4%) were newly administered appropriate antimicrobials after the first laboratory report, whereas an additional 21 (3%) were newly administered appropriate antimicrobials after infection control team (ICT)-intervention. The median time lag (interquartile ranges) from flagging culture bottles as positive to a physician's use of appropriate antimicrobials after the first laboratory report (4 h, 2–7) was significantly (p < 0.001) shorter than that after ICT-intervention (12 h, 10–17). During the study period, no cases of discrepancy between the Gram stain morphology in the first laboratory report and definitive identification of microorganisms in the final laboratory report were observed. Because the timing of flagging culture bottles as positive tends to fall outside normal working hours, immediate 24-h reporting by telephone to disclose the suspected microorganism based on the Gram stain morphology from positive blood cultures may contribute to an early recognition of bacteremia and the physician's use of appropriate antimicrobials.     

The ability of Procalcitonin,lactate, white blood cell count and neutrophil-lymphocyte count ratio to predict blood stream infection. Analysis of a large database

BackgroundThe global burden of death due to sepsis is considerable. Early diagnosis is essential to improve the outcome of this deadly syndrome. Yet, the diagnosis of sepsis is fraught with difficulties. Patients with blood stream infection (BSI) are at an increased risk of complications and death. The aim of this study was to determine the diagnostic accuracy of four readily available biomarkers to diagnose BSI in patients with suspected sepsis.MethodsIn this retrospective, observational, Electronic Medical Record based study we compared the accuracy of procalcitonin (PCT), serum lactate concentration, total white blood cell (WBC) count and the neutrophil-lymphocyte count ratio (NLCR) to diagnose BSI in adult patients presenting to hospital with suspected sepsis. Based on the blood culture results patients were classified into 1 of the following 5 groups: i) negative blood cultures, ii) positive for a bacterial pathogen, iii) positive for a potential pathogen, iv) fungal pathogen and v) potential contaminant. Group 2 was further divided into Gram –ve and Gram +ve pathogens. Receiver operating characteristic (ROC) curves were constructed to compare the diagnostic performance of the biomarkers.ResultsThere were 1767 discreet patient admissions. The median PCT concentration differed significantly across blood culture groups (p < 0.0001). The highest median PCT concentration was observed in patients with a Gram-negative pathogen (17.1 ng/mL; IQR 3.6–49.7) and the lowest PCT in patients with negative blood cultures (0.6 ng/mL; IQR 0.2–2.8). The AUROC was 0.83 (0.79–0.86) for PCT, 0.68 (0.64–0.72) for the NLCR, 0.55 (0.51–0.60) for lactate concentration and 0.52 (0.48–0.57) for the WBC count. The AUROC for PCT was significantly greater than that of the NLCR (p < 0.0001). A PCT less than 0.5 ng/mL had a negative predictive value of 95% for excluding BSI. The best cut-off value of PCT for predicting BSI was 1.5 ng/ml.ConclusionOur results suggest that PCT of less than 0.5 ng/mL may be an effective screening tool to exclude BSI as the cause of sepsis, while the diagnosis of BSI should be considered in patients with a PCT above this threshold. The total WBC count and blood lactate concentration may not be reliable biomarkers for the diagnosis of BSI. The NLCR may be a useful screening test for BSI when PCT assays are not available.     

Are central venous catheter tip cultures reliable after 6-day refrigeration?

Present guidelines recommend culturing only central venous catheter (CVC) tips from patients with suspected catheter-related bloodstream infection (CR-BSI). However, a high proportion of these suspicions are not confirmed. Moreover, CVC tip culture increases laboratory workload, and reports of colonization may be meaningless or misleading for the clinician. Our working hypothesis was that CVC tips should be refrigerated and cultured only in patients with positive blood cultures. We evaluated the effect of 6-day refrigeration of 215 CVC tips. We selected all the catheters with a significant count according to the Maki's roll-plate technique and randomly assigned them to 2 groups. In group A, the catheters were recultured after 24 h of refrigeration, and in group B, the catheters were recultured after 6 days more of refrigeration, so that the refrigeration time evaluated would be of 6 days. The yield of refrigerated CVC tips that grow significant colony counts of primary culture in group B was compared with the yield of refrigerated catheter tips in group A. The difference showed that 6-day refrigeration reduced the number of significant CVCs by 15.2%. Only 61 CVCs were obtained from patients with CR-BSI, and in most of them, blood cultures were already positive before CVC culture, so only 0.91% of the CR-BSI episodes would have been misdiagnosed as culture negative after refrigeration. Refrigeration of CVC tips sent for culture and culturing only those from patients with positive blood cultures reduce the workload in the microbiology laboratory without misdiagnosing CR-BSI.     

Previous cultures are not clinically useful for guiding empiric antibiotics in suspected ventilator-associated pneumonia: secondary analysis from a randomized trial

PURPOSE: To examine the predictive validity of prior cultures at predicting the microorganism isolated at the time of suspicion of ventilator-associated pneumonia (VAP). MATERIALS AND METHODS: We performed a retrospective analysis of a randomized controlled trial of different diagnostic and antibiotic strategies. In a subset of patients with pre-enrollment cultures, we examined agreement between cultures 1 to 3 days before suspicion of VAP and enrollment cultures performed on the day of suspicion of VAP and potential antibiotic error rates (estimated using the equation 1 - crude agreement). RESULTS: Two hundred eighty-one (39%) of 739 patients had pre-enrollment culture. One hundred thirty (46%) of 281 yielded a pathogenic microorganism. In patients with positive pre-enrollment cultures, crude agreement was 0.63 (95% confidence interval, 0.55-0.71) for organism, 0.84 (0.77-0.89) for Gram class, and 0.61 (0.52-0.69) for species with sensitivity. Potential antibiotic error rates ranged from 16% (11%-33%) to 39% (31%-48%). Better agreement (P = .033) occurred in isolates from patients receiving new antibiotics during the surveillance period (0.78 [0.64-0.87]) compared to those not on antibiotics (0.58 [0.45-0.69]), or on no new antibiotics (0.50 [0.32-0.68]). CONCLUSIONS: There is poor agreement between prior cultures and cultures performed at time of suspicion of VAP. Prior cultures should not be used to narrow the spectrum of empiric antibiotics.     

Emergence of MRSA in positive blood cultures from patients with febrile neutropenia—a cause for concern

GOALS OF WORK: Febrile neutropenia (FN) causes considerable morbidity in patients on cytotoxic chemotherapy. Recently, there has been a trend towards fewer Gram-negative and more Gram-positive infections with increasing antibiotic resistance. To assess these patterns, data from a supra-regional cancer centre in Ireland were reviewed. PATIENTS AND METHODS: A 5-year review of all positive blood cultures in patients undergoing anti-cancer chemotherapy was carried out. MAIN RESULTS: Eight hundred and ninety-four patients were reviewed. The mean incidence of FN was 64.2 cases per year. Eight hundred and forty-six blood culture specimens were taken and 173 (20.4%) were culture positive. The isolated organisms were Gram positive (71.1%), Gram negative (27.8%) and fungal (1.1%). Of the Gram-positive organisms, 75.6% were staphylococci. Of these, 67.8% were coagulase-negative staphylococci and 30.1% were Staphylococci aureus. Amongst the S. aureus, 89.3% were methicillin-resistant (MRSA). Vancomycin-resistant enterococci were not identified as a cause of positive blood cultures. CONCLUSIONS: Amongst patients with cancer who develop FN in our hospital, Gram-positive bacteria account for the largest proportion. The high proportion of MRSA as a cause of positive blood cultures is of concern.     

Impact of inappropriate antibiotic therapy on mortality in patients with ventilator-associated pneumonia and blood stream infection: a meta-analysis

OBJECTIVES: Studies have found that initial treatment of ventilator-associated pneumonia (VAP) and blood stream infections (BSI) with inappropriate antimicrobial therapy is associated with higher rates of mortality, but additional studies have failed to confirm this. METHODS: Databases were searched to identify studies that met the following criteria: observational trials, patients with VAP or BSI receiving appropriate and inappropriate antimicrobial therapy, and mortality data. We conducted random-effects model meta-analyses, both with and without adjustment. RESULTS: Meta-analyses of VAP studies using unadjusted and adjusted data indicated that inappropriate therapy significantly increased patients' odds of mortality (odds ratio [OR], 2.34; 95% confidence interval [CI], 1.51-3.63; P = .0001, I 2 = 28.5% and OR, 3.03; 95% CI, 1.12-8.19; P = .0292, I 2 = 89.2%, respectively). Meta-analyses of BSI studies using unadjusted and adjusted data showed that inappropriate therapy significantly increased patients' odds of mortality (OR, 2.33; 95% CI, 1.96-2.76; P < .0001, I 2 = 48.7% and OR, 2.28; 95% CI, 1.43-3.65; P = .0006, I 2 = 88.2%, respectively). CONCLUSIONS: There appears to be an association between initial inappropriate antimicrobial therapy and increased mortality in patients with VAP and BSI.     

Peritoneal fluid cultures rarely alter management in patients with ascites

Study objective: The objective of this study is to determine if the peritoneal fluid culture results in the ascites patient being evaluated for spontaneous bacterial peritonitis (SBP) in the Emergency Department (ED) are used by the inpatient physician to appropriately alter empiric antibiotic treatment. Methods: We performed a retrospective study of all ascitic fluid samples sent from the ED between January 1, 2002 and December 31, 2004. Exclusion criteria included peritoneal fluid samples sent from peritoneal dialysis patients and those undergoing diagnostic peritoneal lavage for trauma. Medical records were examined to determine culture results, initial antibiotic choices, and subsequent changes in antibiotics by the inpatient physician in response to the culture results. The primary outcome measure was the percentage of cases in which ED peritoneal fluid culture results caused inpatient physicians to appropriately change antibiotic coverage. Results: There were 201 ascitic fluid samples, of which 7 (3.5%; 95% confidence interval [CI] 1.4%–7.0%) had a pathogen identified. Of these, only 1 (0.5%; 95% CI .01%–2.4%) resulted in an appropriate change in empiric antibiotic therapy. Although there were additional opportunities for appropriately using the culture results to change the antibiotic coverage in 2 (1%; 95% CI 0.1%–3.6%) patients, coverage was not changed. In fact, it was changed inappropriately in these 2 patients, and in an additional patient on appropriate empiric therapy. Conclusions: The yield from ascitic fluid cultures was low, and when positive, did not appropriately change management according to microbiologic criteria.     

The yield of blood cultures in a department of emergency medicine.

This study sought to determine the yield of blood cultures drawn in the department of emergency medicine. The results of 730 blood cultures taken from 718 patients were retrospectively analysed. The total percentage of positive cultures was 9.7%. Only 3.4% of the blood cultures were classified as true bacteraemia and the rest as contaminants. The commonest type of isolate was coagulase-negative staphylococci (49%), which were considered contaminants in all cases. Other contaminants represented 13.2% of all the positive blood cultures. The following bacteria comprised the group of true bacteraemia: Escherichia coli (12.6%), Streptococcus pneumoniae (9.8%), viridans streptococci (7%), Staphylococcus aureus (2.8%), Bacteroides fragilis (2.8%), Moraxella species (1.4%) and Flavobacterium species (1.4%). Blood cultures were positive in 3.6% of patients with pneumonia and in 10% of patients with urinary tract infections. In patients with fever of unclear source blood cultures were positive in 3.1% of children between 0-36 months of age and in 1.1% of patients older than 16 years. As a whole, patients with positive blood cultures were clinically sicker, a higher percentage of them required admission to the hospital and had higher temperatures or rapidly fatal disease, compared with the group of patients with negative blood cultures. In order to improve the yield of blood cultures in febrile patients, first, better a priori identification of those subjects at high risk for bacteraemia will reduce the number of unnecessary blood cultures and second, sterile venipuncture techniques should be improved in order to reduce the number of contaminants.     

Routine bile cultures during elective cholecystectomy

To assess antibiotic usage and the value of routine intraoperative bile cultures, we retrospectively reviewed 79 patients who had elective cholecystectomy from January to December 1986. Forty patients (57%) received perioperative antibiotics, and 15 (19%) had positive intraoperative bile cultures. During follow-up, the only septic complications identified were wound infections in two patients (3%); one of them had received antibiotics and one had not. Each bile culture cost $60 to $80, and the cultures were not clinically useful. In the absence of risk factors associated with positive bile cultures, the incidence of wound infections or septic complications after cholecystectomy is low. We conclude that routine intraoperative bile cultures and prophylactic antibiotics are not indicated for elective cholecystectomy in low-risk patients.     

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 ≥ 21 mg/dL) and low blood pressure (systolic blood pressure ≤ 90 mmHg). 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 19.2 mg/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 (≥20 mg/dL) or low blood pressure.     

Quantitative blood cultures in candidemia

The relationship between quantitative data on peripheral blood cultures and source of infection was studied in 172 episodes of candidemia that occurred in 169 patients. Clinically, the source of candidemia was an intravascular device in 67 episodes, an extravascular source in 73 episodes, and endocarditis in 2 patients; no source was identified for the other 30 episodes. Colony counts were determined in peripheral blood specimens on the first day of candidemia by the lysis-centrifugation system. High-grade and low-grade candidemia were defined as 25 colony-forming units or more per 10 ml and 10 colony-forming units or fewer per 10 ml of blood, respectively. Of 48 episodes of high-grade candidemia, 43 (90%) were associated with an infected intravascular device; therefore, the presence of high-grade candidemia should prompt the removal of intravascular devices. In contrast, 92 of the 112 episodes of low-grade candidemia (82%) had an extravascular or an unidentified source of candidemia. In patients with infections associated with an intravascular device, colony counts declined significantly within 72 hours after removal of the device in the absence of antifungal therapy; failure to decline suggests an alternative source of persistent infection. Quantitative data from peripheral blood cultures may help distinguish intravascular from extravascular sources of candidemia and aid in assessing the response to the removal of infected intravascular devices.     

某地区小儿血流感染病原菌分布及耐药性分析

目的探讨北海地区小儿患者血流感染(BSI)病原菌分布及其耐药性。方法回顾性分析2013年1月至2016年6月发生BSI的小儿患者临床资料。结果本地区95.3%的小儿BSI为社区获得性感染。革兰阳性球菌与阴性杆菌所占比例分别为53.5%、46.5%。万古霉素、利奈唑胺对阳性球菌耐药率均为0.0%;哌拉西林、哌拉西林/他唑巴坦、头孢吡肟、美罗培南对革兰阴性杆菌的耐药率分别9.3%、0.0%、9.1%、5.0%。结论革兰阳性球菌与阴性杆菌感染比例基本一致。万古霉素、利奈唑胺可作阳性球菌BSI的经验用药;哌拉西林、哌拉西林/他唑巴坦、头孢吡肟、美罗培南可作革兰阴性杆菌BSI的经验用药。     

Role of routine blood cultures in detecting unapparent infections during continuous renal replacement therapy

Objective Continuous renal replacement therapy (CRRT) is frequently employed in the management of renal failure in unstable intensive care patients. At some centers, blood cultures are performed routinely while on CRRT to monitor for occult bacteremia. We questioned the role of routine blood cultures (RBC) in diagnosing underlying infections in these often afebrile patients.Design Retrospective cohort study (1998–2003).Setting Medical, surgical and pediatric intensive care units in a tertiary care teaching hospital.Methods/measurements We undertook a retrospective chart review of all 101 episodes of CRRT performed in our hospital since 1998. The primary endpoint of the study was the number of positive cultures that changed patient management. For each positive result, documented infection and parameters of sepsis were noted.Results There were 101 treatments of CRRT in 98 patients. A total of 698 routine RBC bottles were drawn, a mean of 7.2 ± 7 per patient; of those, 29 (4%) were positive in 17 patients, documenting 11 bacteremias. Six positive cultures represented contaminants. In all but one case, infection was known or signs of sepsis were present prior to receipt of the culture result.Conclusions For patients on CRRT, RBC are rarely positive, and do not detect occult infection in the absence of clinical evidence of infection for the majority of patients. Because routine cultures utilize significant resources, and can result in false-positive results, RBC should not be performed in these patients. Careful clinical monitoring, with blood cultures performed at the first clinical suggestion of an infection, should detect all clinically relevant infections.