Reassessment of the routine anaerobic culture and incubation time in the BacT/Alert FAN blood culture bottles

A total of 9,130 blood cultures were collected from adult patients with suspected bloodstream infections. The recommended 20 mL sample of blood was divided equally between the aerobic and anaerobic FAN bottles and monitored in the BacT/Alert Microbial Detection System for a total of 5 days. There were 757 clinically significant positive culture pairs from 291 patients. Significant differences were found with greater recovery of Pseudomonas aeruginosa (p < 0.001), Acinetobacter spp. (p = 0.002), coagulase-negative staphylococci other than Staphylococcus epidermidis (p = 0.002), and Candida spp. (p < 0.001) from the aerobic bottle and greater recovery of anaerobic bacteria (p < 0.001) from the anaerobic bottle. Significantly more episodes of P. aeruginosa bacteremia (p < 0.003) and candidemia (p < 0.001) were detected by the aerobic FAN bottle and significantly more episodes of anaerobic bacteremia (p < 0.001) were detected by the anaerobic FAN bottle (Table 2). No other significant differences between systems in their detection of bacteremias were noted. Anaerobic bacteremias were encountered in diverse and often unpredictable clinical settings. All clinically significant episodes of bloodstream infection were detected within 4 days of incubation of their cultures. We conclude routine, rather than selective, use of the anaerobic FAN bottle in the blood culture set and a 4-day incubation of blood cultures in the BacT/Alert aerobic and anaerobic FAN bottles is an appropriate routine procedure.     

Difference in time to positivity of hub-blood versus nonhub-blood cultures is not useful for the diagnosis of catheter-related bloodstream infection in critically ill patients.

OBJECTIVE: The differential time to positivity (DTTP), defined as the difference in time necessary for the blood cultures taken by a peripheral puncture and through the catheter to become positive has been suggested to be useful in differentiating between catheter-related bloodstream infection (CR-BSI) and other sources of bacteremia. A DTTP of >120 mins was found predominantly in CR-BSI. The objective of our study was to investigate whether DTTP is useful for the diagnosis of CR-BSI in a medical-surgical intensive care unit. DESIGN: Prospective clinical study. SETTING: A 60-bed medical-surgical intensive care unit of a university hospital. PATIENTS: One hundred consecutive adult patients from whom catheter(s) were to be removed for suspected CR-BSI were studied. INTERVENTION: A blood culture (using aerobic and anaerobic culture bottles) was first taken from a new puncture site. Next, a blood culture was taken through every intravascular catheter in place. MEASUREMENTS AND RESULTS: DTTP was calculated using the automated BacT/Alert blood culture system. Three patients had CR-BSI and nine patients had noncatheter-related bacteremia. Five patients had catheter-related sepsis without proven bacteremia. There was no significant difference in median DTTP between patients with CR-BSI and noncatheter-related bacteremia (2.1 hrs and 3.3 hrs, respectively; p =.6). Moreover, catheter-related sepsis in patients without bacteremia could not be detected using DTTP. CONCLUSION: DTTP seems not to be useful for the diagnosis of CR-BSI in a medical-surgical intensive care unit.     

Blood Cultures in Adult Patients Released from an Urban Emergency Department: A 15-month Experience

Objective: To determine the frequency of positive blood cultures obtained from adult patients with potential occult bacteremia released from an urban ED and how often these positive cultures alter the subsequent patient course or management. Methods: This retrospective case series study was conducted at the ED of a large, urban teaching hospital. The study population consisted of a convenience sample of adult patients who presented to the ED with evidence of fever or other clinical conditions suggesting the possibility of bacteremia. The records of all patients who had blood cultures done and who were not admitted to an inpatient service were reviewed. Follow-up was obtained for all patients for whom culture results were positive. A substantial influence on the medical management or clinical course by a (noncontaminant) positive blood culture result was defined as a positive result that directly led to: further diagnostic testing, hospital admission, initiation or alteration of antibiotic therapy, or a different diagnosis. Culture-positive patients who were noncompliant with requested ED follow-up were included in this estimate. An estimate of the laboratory charges per diagnosis of bacteremia also was derived. Results: Only 24 of 1,350 patients (1.8% of the study population; 95% CI 1.1–2.5%) had true-positive blood cultures. Only 7 patients (0.52% of the population; 95% CI 0.14–0.90%) potentially had their medical management affected by the positive blood culture results. Based on the laboratory charges associated with all blood cultures for this patient group, the cost per clinically significant positive blood culture result was $11,570. Conclusions: The prevalence of bacteremia was 1.8% among the released patients who had blood cultures obtained in the ED. Furthermore, only 0.52% of the patients had positive blood cultures that potentially affected their medical management. Further study is warranted to identify specific criteria for selecting ambulatory patients for whom the use of blood cultures may be cost-effective.     

Anaerobic bacteremia: the yield of positive anaerobic blood cultures: patient characteristics and potential risk factors.

The anaerobic blood culture (AN) bottle is routinely used in Japan with little discussion as to its justification or validity. We retrospectively studied the AN bottle yield of obligate anaerobes and the characteristics of, and potential risk factors in, patients with anaerobic bacteremia during a 2-year period (1999-2000) at four university hospitals and one community hospital. Thirty-four of 18,310 aerobic and anaerobic blood culture sets from 6,215 patients taken at the university hospitals, and 35 of 2,464 samples taken from 838 patients at the community hospital, yielded obligate anaerobes. Bacteroides species and Clostridium species accounted for 60% of the isolates. Fifty-seven patients from 69 blood culture sets containing anaerobes had clinically significant anaerobic bacteremia. Among these 57 patients, 24 (49%) were oncology patients, 40 (70%) had an obvious source of anaerobic infection, 15 (26%) had recent surgery and/or were in an immunosuppressed state. We concluded that the recovery rate of obligate anaerobes isolated from AN bottles was low, and the patients with anaerobic bacteremia had limited number of underlying diseases or potential risk factors for anaerobic infections. Therefore, anaerobic blood cultures may be selectively used according to the potential risk for anaerobic infections.     

Who Needs a Blood Culture? A Prospectively Derived and Validated Prediction Rule

The study objective was to derive and validate a clinical decision rule for obtaining blood cultures in Emergency Department (ED) patients with suspected infection. This was a prospective, observational cohort study of consecutive adult ED patients with blood cultures obtained. The study ran from February 1, 2000 through February 1, 2001. Patients were randomly assigned to derivation (2/3) or validation (1/3) sets. The outcome was "true bacteremia." Features of the history, co-morbid illness, physical examination, and laboratory testing were used to create a clinical decision rule. Among 3901 patients, 3730 (96%) were enrolled with 305 (8.2%) episodes of true bacteremia. A decision rule was created with "major criteria" defined as: temperature > 39.5 degrees C (103.0 degrees F), indwelling vascular catheter, or clinical suspicion of endocarditis. "Minor criteria" were: temperature 38.3-39.4 degrees C (101-102.9 degrees F), age > 65 years, chills, vomiting, hypotension (systolic blood pressure < 90 mm Hg), neutrophil% > 80, white blood cell count > 18 k, bands > 5%, platelets < 150 k, and creatinine > 2.0. A blood culture is indicated by the rule if at least one major criterion or two minor criteria are present. Otherwise, patients are classified as "low risk" and cultures may be omitted. Only 4 (0.6%) low-risk patients in the derivation set and 3 (0.9%) low-risk patients in the validation set had positive cultures. The sensitivity was 98% (95% confidence interval [CI] 96-100%) (derivation) and 97% (95% CI 94-100%) (validation). We developed and validated a promising clinical decision rule for predicting bacteremia in patients with suspected infection.     

Predictors of bacteremia in emergency department patients with suspected infection

Objectives

The goal of this study is to identify clinical variables associated with bacteremia. Such data could provide a rational basis for blood culture testing in emergency department (ED) patients with suspected infection.

Methods

This is a secondary analysis of a prospective cohort of ED patients with suspected infection. Data collected included demographics, vital signs, medical history, suspected source of infection, laboratory and blood culture results and outcomes. Bacteremia was defined as a positive blood culture by Centers for Disease Control criteria. Clinical variables associated with bacteremia on univariate logistic regression were entered into a multivariable model.

Results

There were 5630 patients enrolled with an average age of 59.9 ± 19.9 years, and 54% were female. Blood cultures were obtained on 3310 (58.8%). There were 409 (12.4%) positive blood cultures, of which 68 (16.6%) were methicillin-resistant Staphylococcus aureus (MRSA) and 161 (39.4%) were Gram negatives. Ten covariates (respiratory failure, vasopressor use, neutrophilia, bandemia, thrombocytopenia, indwelling venous catheter, abnormal temperature, suspected line or urinary infection, or endocarditis) were associated with all-cause bacteremia in the final model (c-statistic area under the curve [AUC], 0.71). Additional factors associated with MRSA bacteremia included end-stage renal disease (odds ratio [OR], 3.9; 95% confidence interval [CI], 1.9-7.8) and diabetes (OR, 2.0; 95% CI, 1.1-3.6) (AUC, 0.73). Factors strongly associated with Gram-negative bacteremia included vasopressor use in the ED (OR, 2.8; 95% CI, 1.7-4.6), bandemia (OR, 3.5; 95% CI, 2.3-5.3), and suspected urinary infection (OR, 4.0; 95% CI, 2.8-5.8) (AUC, 0.75).

Conclusions

This study identified several clinical factors associated with bacteremia as well as MRSA and Gram-negative subtypes, but the magnitude of their associations is limited. Combining these covariates into a multivariable model moderately increases their predictive value.     

Febrile neutropenia and Fusobacterium bacteremia: clinical experience with 13 cases

OBJECTIVES: To assess the disease spectrum of Fusobacterium bacteremia in our neutropenic patients and review the literature. METHODS: This was a 6.5-year retrospective study in which all the records of neutropenic patients with Fusobacterium bacteremia were analyzed. RESULTS: Fusobacterium bacteremia was found in 13 neutropenic patients, 10 with hematological malignancies and 3 with solid tumors. The standard clinical presentation was that of primary bacteremia with benign evolution under antibiotics with anaerobic coverage. Most patients presented with oral mucositis as the probable portal of entry. Coinfection with other germs was documented in four patients. No patient had a localized infection documented. Most patients were receiving ciprofloxacin chemoprophylaxis. None of the patients had catheter-related infection. All tested strains were susceptible to all standard anaerobic agents. Fusobacterium spp. were responsible for 5% of bacteremias in neutropenic patients in our hospital during the last 6.5 years. CONCLUSION: Fusobacterium bacteremia is a possible cause of febrile neutropenia, especially in the setting of quinolone prophylaxis and oral mucositis after intense chemotherapeutic regimens. We think that its benign outcome if there is no localized infection detected does not justify the use of antianaerobic prophylaxis. Combination of beta-lactams and beta-lactamase inhibitors is a safe and reasonable treatment.     

The use of the arterial line as a source for blood cultures

OBJECTIVE: To determine the reliability of blood cultures obtained through indwelling arterial lines as compared to that of blood cultures obtained by venipuncture. DESIGN: A prospective observational study. SETTING: Six-bed mixed medical surgical intensive care unit (ICU) of a 550-bed university-affiliated medical center. MEASUREMENTS: During a 3-month period blood culture sets, when clinically indicated, were drawn in parallel from indwelling arterial catheters and one-time venipuncture and the results compared. Each blood sample consisted of 15 ml and was distributed equally between three blood culture bottles: aerobic, anaerobic and one aerobic resin-containing bottle. Blood culture results from the two sources were compared according to preset definitions. MAIN RESULTS: During the study period 90 parallel blood culture sets (540 bottles) were obtained from 36 patients. Forty-three (16%) venipuncture bottles were positive versus 88 (32%) arterial line culture bottles (p < 0.001). Of the parallel sets, 83% yielded equivalent results - either both sterile or both growing the same organism. Amongst the discordant sets, the arterial line cultures grew 37 gram-positive and 18 gram-negative isolates not found in venipuncture sets (i.e. 50% of 109 arterial line isolates), while only two gram-positive isolates were solely grown in venipuncture cultures (4% of all 55 venipuncture isolates, p < 0.001). On clinical correlation, all the gram-positive organisms in the discordant cultures were found not to reflect bacteremia, while five of the 18 gram-negative isolates (28%) grown only in arterial line cultures probably did reflect ongoing bacteremia. CONCLUSION: The results of blood cultures taken from the arterial line are frequently equivalent to those taken from venipuncture. When discordant, the growth of gram-positive bacteria almost certainly reflects contamination or arterial line colonization, whereas the growth of gram-negative bacteria may have to be considered as reflecting bacteremia.     

Blood cultures should be collected for acute cholangitis regardless of severity

BackgroundDespite the high frequency of bacteremia in acute cholangitis, the indications for blood cultures and the relationship between the incidence of bacteremia and severity of acute cholangitis have not been well established. This study examined the association between the 2018 Tokyo Guidelines (TG18) severity grading for acute cholangitis and incidence of bacteremia to identify the need for blood cultures among patients with acute cholangitis in each severity grade.MethodsPatients with acute cholangitis who visited our emergency department between 2019 and 2020 were retrospectively investigated. Patients administered antibiotics within 48 h of hospital arrival, whose prothrombin time-international normalized ratios were not measured, or who were suspected of false bacteremia were excluded.ResultsOut of the included 358 patients with acute cholangitis, blood cultures were collected from 310 (87%) patients, of which 148 (48%) were complicated with bacteremia. As the TG18 severity grading increased, the frequency of bacteremia increased (Grade I, 35% [59/171]; Grade II, 59% [48/82]; Grade III, 74% [42/57]; P <0.001). Agreement with the TG18 diagnostic criteria (unfulfilled, suspected, or definite) was not different between patients with and without bacteremia; however, 36% (14/39) of the patients with “unfulfilled” criteria were complicated with bacteremia.ConclusionsAs the severity of acute cholangitis increased, the frequency of bacteremia increased; however, the incidence of bacteremia was high even in mild cases and cases that did not meet the TG18 diagnostic criteria. Blood cultures should be collected regardless of the severity of acute cholangitis for patients who visit the emergency department.     

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.     

Inpatient utilization of blood cultures drawn in an urban ED

Bloodstream infections are now ranked as the 10th leading cause of death in the United States. Given the severity of bacteremia, physicians routinely order multiple sets of blood cultures in the emergency department. This is a retrospective chart review on 1124 patients admitted to the hospital for suspected bacteremia during calendar year 2004. The aims of the present investigation were to investigate the overall utility of blood cultures by the admitting services and to identify patient factors that might influence culture yield. Data were collected regarding patient demographics, comorbidities, vital signs, laboratory results, antibiotic use, blood culture results, and notation of blood culture results by admitting physicians. Increased age, elevated heart rate, use of chemotherapy, decreased sodium, and increased blood urea nitrogen significantly increased the likelihood of yielding a positive blood culture in our patient population. Culture results were noted in 517 patient charts by the primary medical team (46.0%) and were adjusted in 223 patients (43.3%). Of 1124 cultures, 10.3% were positive in at least 1 bottle for a pathogenic organism (true positive), and 6.3% were contaminants (false positive). In conclusion, cultures must be followed closely by the admitting physician after being obtained. Our data emphasize that blood cultures are currently not well used by the admitting physicians and that measures need to be taken to improve the overall utility of blood culture data by the admitting physician.     

Blood cultures ordered in the adult emergency department are rarely useful.

OBJECTIVES: Although blood cultures are commonly ordered in the emergency department, there is controversy about their utility. This study aimed to determine the usefulness of blood cultures in the management of patients presenting to a tertiary adult teaching hospital emergency department in Perth, Western Australia. METHODS: A detailed chart review was undertaken of all blood cultures taken in our emergency department over a 2-month period. All patients within the hospital having blood cultures taken were identified; from this group, blood cultures originating from the emergency department were reviewed. Data were collected concerning patient demographics, culture indication, vital signs, culture outcome, disposition and alterations in management resulting from the blood culture. RESULTS: 218 blood cultures were ordered from the emergency department during the study period. This represented 4.0% (218/5478) of the total number of patients seen. Of the 218 cultures, only 30 were positive (13% of the study population), with 16 (7.3%) probable contaminants and 14 (6.4 %) true positives. No anaerobic isolates were identified. Of the 14 significantly positive blood cultures, the result influenced management in six patients, resulting in a useful culture rate of 2.8% (6/218). CONCLUSION: Blood cultures are ordered on a significant number of patients seen in the emergency department but rarely alter management. Our findings in conjunction with other studies suggest that eliminating blood cultures in immunocompetent patients with common illnesses such as urinary tract infection, community acquired pneumonia and cellulitis, may significantly reduce the number of blood cultures, producing substantial savings without jeopardizing patient care. This needs prospective study and validation.     

Inadequacy of Temperature and White Blood Cell Count in Predicting Bacteremia in Patients with Suspected Infection

Background

Early treatment of sepsis in Emergency Department (ED) patients has lead to improved outcomes, making early identification of the disease essential. The presence of systemic inflammatory response criteria aids in recognition of infection, although the reliability of these markers is variable.

Study Objective

This study aims to quantify the ability of abnormal temperature, white blood cell (WBC) count, and bandemia to identify bacteremia in ED patients with suspected infection.

Methods

This was a post hoc analysis of data collected for a prospective, observational, cohort study. Consecutive adult (age ≥ 18 years) patients who presented to the ED of a tertiary care center between February 1, 2000 and February 1, 2001 and had blood cultures obtained in the ED or within 3 h of admission were enrolled. Patients with bacteremia were identified and charts were reviewed for presence of normal temperature (36.1–38°C/97–100.4°F), normal WBC (4–12 K/μL), and presence of bandemia (> 5% of WBC differential).

Results

There were 3563 patients enrolled; 289 patients (8.1%) had positive blood cultures. Among patients with positive blood cultures, 33% had a normal body temperature and 52% had a normal WBC count. Bandemia was present in 80% of culture-positive patients with a normal temperature and 79% of culture-positive patients with a normal WBC count. Fifty-two (17.4%) patients with positive blood cultures had neither an abnormal temperature nor an abnormal WBC.

Conclusion

A significant percentage of ED patients with blood culture-proven bacteremia have a normal temperature and WBC count upon presentation. Bandemia may be a useful clue for identifying occult bacteremia.     

Prior colonization is associated with increased risk of antibiotic-resistant Gram-negative bacteremia in cancer patients

We hypothesized that prior colonization with antibiotic-resistant Gram-negative bacteria is associated with increased risk of subsequent antibiotic-resistant Gram-negative bacteremia among cancer patients. We performed a matched case-control study. Cases were cancer patients with a blood culture positive for antibiotic-resistant Gram-negative bacteria. Controls were cancer patients with a blood culture not positive for antibiotic-resistant Gram-negative bacteria. Prior colonization was defined as any antibiotic-resistant Gram-negative bacteria in surveillance or non-sterile-site cultures obtained 2–365 days before the bacteremia. Thirty-two (37%) of 86 cases and 27 (8%) of 323 matched controls were previously colonized by any antibiotic-resistant Gram-negative bacteria. Prior colonization was strongly associated with antibiotic-resistant Gram-negative bacteremia (odds ratio [OR] 7.2, 95% confidence interval [CI] 3.5–14.7) after controlling for recent treatment with piperacillin-tazobactam (OR 2.5, 95% CI 1.3–4.8). In these patients with suspected bacteremia, prior cultures may predict increased risk of antibiotic-resistant Gram-negative bacteremia.     

Clinical significance of Staphylococcus saprophyticus identified on blood culture in a tertiary care hospital

Staphylococcus saprophyticus is a well-known cause of acute uncomplicated urinary tract infection in young women. However, the clinical significance of this organism isolated from blood culture has not been determined. We assessed the clinical significance and characteristics of S. saprophyticus identified on blood culture. A total of 24 patients were identified, and 7 patients (29.2%) were considered to have clinically significant bacteremia. Of the 7 patients with clinically significant bacteremia, hematologic malignancy was the most common underlying illness (5 patients), and tunneled-central venous catheter was the most common portal of entry (4 patients). In no case did S. saprophyticus bacteremia originate from the urinary tract. One patient died during hospitalization. However, the death was not directly related to bacteremia. In conclusion, our data suggest that bacteremia caused by S. saprophyticus is most commonly associated with tunneled-central venous catheter in patients with hematologic malignancies and may be associated with a lower risk of mortality.     

Blood Cultures Do Not Change Management in Hospitalized Patients with Community-acquired Pneumonia

Objectives: To determine if blood cultures identify organisms that are not appropriately treated with initial empiric antibiotics in hospitalized patients with community-acquired pneumonia, and to calculate the costs of blood cultures and cost savings realized by changing to narrower-spectrum antibiotics based on the results.
Methods: This was a retrospective observational study conducted in an urban academic emergency department (ED). Patients with an ED and final diagnosis of community-acquired pneumonia admitted between January 1, 2001, and August 30, 2003, were eligible when the results of at least one set of blood cultures obtained in the ED were available. Exclusion criteria included documented human immunodeficiency virus infection, immunosuppressive illness, chronic renal failure, chronic corticosteroid therapy, documented hospitalization within seven days before ED visit, transfer from another hospital, nursing home residency, and suspected aspiration pneumonia. The cost of blood cultures in all patients was calculated. The cost of the antibiotic regimens administered was compared with narrower-spectrum and less expensive alternatives based on the results.
Results: A total of 480 patients were eligible, and 191 were excluded. Thirteen (4.5%) of the 289 enrolled patients had true bacteremia; the organisms isolated were sensitive to the empiric antibiotics initially administered in all 13 cases (100%; 95% confidence interval = 75% to 100%). Streptococcus pneumoniae and Haemophilus influenzae were isolated in 11 and two patients, respectively. The potential savings of changing the antibiotic regimens to narrower-spectrum alternatives was only 170.
Conclusions: Appropriate empiric antibiotics were administered in all bacteremic patients. Antibiotic regimens were rarely changed based on blood culture results, and the potential savings from changes were minimal.     

High incidence of bloodstream infection detected by surveillance blood cultures in hematology patients on corticosteroid therapy

Purpose

The aim of our study was to evaluate the frequency of “occult” bacteremia/fungemia as well as the diversity of pathogens involved in hematology patients treated with corticosteroids.

Methods

Daily surveillance blood cultures were taken from patients treated with corticosteroids as part of their intensive chemotherapy or during graft-versus-host disease following hematopoietic stem cell transplantation during a 3-year period (2006–2009). We reviewed the frequency of occult bacteremia/fungemia as well as the pathogens involved.

Results

During the 3-year period, 3,821 bottles were cultured from 215 patients and 4.9?% of the bottles tested were positive. Surveillance blood cultures revealed bloodstream infection in 24?% of the patients (definite bloodstream infection in 16?%). Seventy-five percent of patients were still afebrile when microorganisms were detected. The main risk group was acute lymphocytic leukemia patients undergoing remission induction chemotherapy. The pathogens cultured most frequently were coagulase-negative staphylococci, enterococci, Escherichia coli, and Pseudomonas aeruginosa.

Conclusions

A high incidence of occult bacteremia was detected by surveillance blood cultures. Further studies are needed to evaluate if a strategy based on surveillance blood cultures can reduce mortality related to bloodstream infections.     

Procalcitonin reflects bacteremia and bacterial load in urosepsis syndrome: a prospective observational study

Introduction

Guidelines recommend that two blood cultures be performed in patients with febrile urinary tract infection (UTI), to detect bacteremia and help diagnose urosepsis. The usefulness and cost-effectiveness of this practice have been criticized. This study aimed to evaluate clinical characteristics and the biomarker procalcitonin (PCT) as an aid in predicting bacteremia.

Methods

A prospective observational multicenter cohort study included consecutive adults with febrile UTI in 35 primary care units and 8 emergency departments of 7 regional hospitals. Clinical and microbiological data were collected and PCT and time to positivity (TTP) of blood culture were measured.

Results

Of 581 evaluable patients, 136 (23%) had bacteremia. The median age was 66 years (interquartile range 46 to 78 years) and 219 (38%) were male. We evaluated three different models: a clinical model including seven bed-side characteristics, the clinical model plus PCT, and a PCT only model. The diagnostic abilities of these models as reflected by area under the curve of the receiver operating characteristic were 0.71 (95% confidence interval (CI): 0.66 to 0.76), 0.79 (95% CI: 0.75 to 0.83) and 0.73 (95% CI: 0.68 to 0.77) respectively. Calculating corresponding sensitivity and specificity for the presence of bacteremia after each step of adding a significant predictor in the model yielded that the PCT > 0.25 μg/l only model had the best diagnostic performance (sensitivity 0.95; 95% CI: 0.89 to 0.98, specificity 0.50; 95% CI: 0.46 to 0.55). Using PCT as a single decision tool, this would result in 40% fewer blood cultures being taken, while still identifying 94 to 99% of patients with bacteremia. The TTP of E. coli positive blood cultures was linearly correlated with the PCT log value; the higher the PCT the shorter the TTP (R² = 0.278, P = 0.007).

Conclusions

PCT accurately predicts the presence of bacteremia and bacterial load in patients with febrile UTI. This may be a helpful biomarker to limit use of blood culture resources.     

Clinical and microbiological characteristics in cases of positive blood cultures at Shin-Kokura Hospital during a period of 5 years

In order to evaluate the present state of bacteremia, we investigated the clinical and microbiological characteristics of positive blood culture cases hospitalized in Shin-Kokura Hospital from January 1998 through December 2002. Seventy-five cases showed positive blood cultures during the 5 years, and 48 cases (64%) were 70 years old or more. Most of the cases had underlying diseases, such as malignancy. The diagnoses of the infectious diseases found included pneumonia (9 cases), enteric infection (9 cases), hepatobiliary infection (8 cases), urinary tract infection (8 cases), and endocarditis (6 cases). A total of 102 strains of microorganism were isolated, and Gram-positive bacteria accounted for 64.7% of the cases, with Gram-negative bacteria accounting for 29.4%. Most of the isolated microorganisms showed good susceptibility to antimicrobial agents except for MRSA. Antimicrobial agents were used for 54 cases of bacteremia, and 33 patients improved, but 21 patients died, including 10 whose death was due to infection. In this study, the 54 cases of bacteremia (72% of all cases with a positive blood culture) showed a mortality rate of 18.5% due to infection, in spite of adequate antimicrobial treatment. Our data suggest that physicians should recognize the difficulty of treating bacteremia, and should pay close attention to the physical condition of patients with bacteremia.     

Clinical prediction rule is more useful than qSOFA and the Sepsis-3 definition of sepsis for screening bacteremia

BackgroundClinical guidelines recommend blood cultures for patients suspected with sepsis and bacteremia. Sepsis-3 task force introduced the new definition of sepsis in 2016; however, the relationship between the Sepsis-3 definition of sepsis and bacteremia remains unclear. This study aimed to investigate how to detect patients who need blood cultures.MethodsConsecutive patients who visited the emergency department in our hospital with suspected symptoms of bacterial infection and with collected blood culture were retrospectively examined between April and September 2019. The relationship between bacteremia and Sepsis-3 definition of sepsis, and the relationship between bacteremia and clinical scores (quick-Sequential Organ Failure Assessment [qSOFA], systematic inflammatory response syndrome [SIRS], and Shapiro's clinical prediction rule) were investigated. In any scores used, ≥2 points were considered positive.ResultsAmong the 986 patients who met the inclusion criteria, 171 (17%) were complicated with bacteremia and 270 (27%) were patients with sepsis. Sepsis was more frequent (61% vs. 20%, P < 0.001) and all clinical scores were more frequently positive in patients with bacteremia than in those without (qSOFA, 23% vs. 9%; SIRS, 72% vs. 58%; Shapiro's clinical prediction rule, 88% vs. 49%; P < 0.001). Specificity to predict bacteremia was high in sepsis and positive qSOFA (0.80 and 0.91, respectively), whereas sensitivity was high in positive SIRS and Shapiro's clinical prediction rule (0.72 and 0.88, respectively); however, no clinical definitions and scores had both high sensitivity and specificity. The area under the receiver operating characteristic curves were 0.59 (95% confidence interval, 0.55–0.64), 0.60 (0.56–0.65), and 0.78 (0.74–0.82) in qSOFA, SIRS, and Shapiro's clinical prediction rule, respectively.ConclusionBlood cultures should be obtained for patients with sepsis and positive qSOFA because of its high specificities to predict bacteremia; however, because of low sensitivities, Shapiro's clinical prediction rule can be more efficiently used for screening bacteremia.