Clinical and epidemiologic significance of coagulase-negative staphylococci bacteremia in a tertiary care university Israeli hospital

OBJECTIVES: To characterize the clinical significance of coagulase-negative staphylococci (CNS) bacteremia. DESIGN: Prospective cohort study. SETTING: A 900-bed hospital in Haifa, Israel, from November 1996 to March 1997. RESULTS: Of 137 episodes of positive blood cultures for CNS, 41 (30%) were considered as true infection. Twenty-seven of 119 episodes associated with only 1 blood culture positive for CNS (23%) met the definition of infection as compared with 14 of 18 episodes (78%) associated with 2 or more blood cultures positive for CNS (P <.001). Methicillin resistance was significantly more frequent among Staphylococcus epidermidis isolates of episodes of true bacteremia than of episodes of contamination (15 of 22 [68%] vs. 11 of 33 [33%], respectively; P =.02). S hominis was isolated only in episodes considered as contamination (P =.01). It was estimated that CNS represents 24% of all nosocomial bloodstream pathogens. When CNS were isolated in the first 48 hours of hospitalization, an intravascular device was more frequently associated with episodes of true bacteremia than in those considered as contamination (7 of 7 [100%] vs. 10 of 57 [18%], respectively; P <.001). The mortality rate among patients with true CNS bacteremia was 16%. CONCLUSION: Some laboratory parameters may help identify episodes of true CNS bacteremia, which appears to be more common than previously considered.     

Rapid classification of positive blood cultures

OBJECTIVE: 1) To validate a previously developed prediction model to aid physicians in differentiating true positive blood cultures from contaminants when the laboratory first calls with a positive result, and 2) to determine whether it could be modified to make it more practical for clinical use without altering predictability. DESIGN: A prospective cohort study of hospitalized patients (validation set) who had blood cultures done over a two-month period. Data collected included the seven independent predictors in the rapid classification of positive blood cultures model. The model was modified by eliminating one of the predictors (which required clinical data) but maintaining the laboratory components (morphologic and Gram stain characteristics, number of bottles positive, and time to positivity). The “blood culture episode” was the unit of evaluation. A blood culture episode was defined as a 48-hour period beginning with the drawing of blood for the culture and included any blood cultures obtained during that time period. Receiver operating characteristic (ROC) curve analysis was used to compare the predictabilities of these models. SETTING: A 550-bed, university-affiliated county hospital that is a regional trauma center and has the only burn treatment unit in the region. PATIENTS: All adult (≥16 years old) patients who had blood cultures done during the study period were eligible. Only patients with positive blood cultures were included in the study. INTERVENTIONS: None. MAIN RESULTS: Of 559 blood culture episodes identified, 139 (25%) included the growth of one or more organisms; 62 (45%) of the 139 episodes represented true bacteremia. By ROC curve analysis, there was no significant difference in the mean areas under the curve (AUCs) (±SE) of the model in the derivation set (the previously developed model) (0.93±0.02) compared with the validation set (0.89±0.03; p=0.29). In the validation set there was no significant difference in the mean AUCs when the model was modified (0.89±0.03) by removing the clinical component vs the unmodified model (0.89±0.03; p=0.98). CONCLUSIONS: The rapid classification of blood cultures model was validated in a general hospital population. Predictability of the model was not altered significantly by eliminating one component that required clinical data. Because the modified model requires only laboratory information, this may allow reporting of the probability of true bacteremia at the time a positive blood culture is initially reported to physicians. This information may aid physicians in interpreting the positive blood culture.     

Colonization and molecular epidemiology of coagulase-negative Staphylococcal bacteremia in cancer patients: a pilot study

BACKGROUND: Controversy surrounds the source (skin vs mucosa) of coagulase-negative staphylococci (CoNS) bacteremia in cancer patients. Determining the source of this infection has clinical and epidemiologic implications. OBJECTIVE: To determine the source(s) of CoNS bacteremia in cancer patients. METHODS: Between November 1998 and October 2000, cultures of nasal and rectal mucosa and skin at central venous catheter (CVC) sites were obtained in 62 patients (66 episodes) with CoNS-positive blood culture(s). Bacteremia was classified as true, indeterminate, or unlikely on the basis of clinical and microbiologic findings. Molecular relatedness of strains isolated from the blood and from colonized sites of patients with true and those with unlikely bacteremia was examined using pulsed-field gel electrophoresis (PFGE). RESULTS: CoNS colonization was present in 55 episodes (83%). The nasal mucosa was the most frequently colonized site (86%), followed by rectal mucosa (40%) and skin at site of CVC insertion (38%) (P < .001). Colonization at > or =1 site was common. True and unlikely bacteremia accounted for 11 and 10 episodes, respectively, with the remaining 45 episodes considered undetermined or had negative surveillance cultures. Among patients with true bacteremia, 6 mucosal isolates and only 1 skin isolate were related by PFGE to the blood isolate recovered from the same patient. CONCLUSION: Mucosa is the most common site of CoNS colonization and is the likely source of CoNS bacteremia in cancer patients.     

An investigation of enterococcal bacteremia

Records of all 34 patients with positive blood cultures for enterococcus at Mount Sinai Medical Center of Greater Miami in 1981 were reviewed. Twenty-four true bacteremias were identified from sources including the pelvis/abdomen (9), urinary tract (6), wounds (2), IV catheter (2), contaminated needle (1), endocarditis (1), and primary bacteremia (3). Sixteen of the 24 true bacteremias were hospital acquired, and these infectious accounted for 7 of 9 (78%) fatal outcomes. Fourteen of 16 patients with hospital-acquired infection received prior antibiotic therapy. Eight (24%) of the original 34 patients had positive blood cultures for enterococcus as a result of cross-contamination from an automated blood culture analyzer. The rate of cross-contamination per positive blood culture for enterococcus in 1981 was 22%. Two remaining patients in the original series could not be placed in a category of true infection of cross-contamination. Although there was a real increase in the number of enterococcal bacteremias in 1981, a much larger apparent increase was explained by several episodes of pseudobacteremia.     

Molecular typing of coagulase-negative staphylococci from blood cultures does not correlate with clinical criteria for true bacteremia

PURPOSE: Determining whether a blood culture that contains coagulase-negative staphylococci represents bacteremia or contamination is a clinical dilemma. We compared molecular-typing results of coagulase-negative staphylococcal blood culture isolates with clinical criteria for true bacteremia. SUBJECTS AND METHODS: Pulsed-field gel electrophoresis and arbitrary primed polymerase chain reaction (PCR) were used to determine whether patients with two or more blood cultures with coagulase-negative staphylococcal isolates had the same strain of organism in each culture (same strain bacteremia). We evaluated three different clinical criteria for bacteremia: whether the patient received more than 4 days of antibiotics, whether there was an explicit note in the medical chart in which the physician diagnosed a true bacteremia, and the Centers for Disease Control surveillance criteria for primary bloodstream infection. Agreement between same-strain bacteremia and each definition was examined, based on the assumption that most true infections should be the result of a single strain. RESULTS: The study sample consisted of 42 patients and 106 isolates. Nineteen of the 42 bacteremias (45%) were the same strain. Classification of bacteremias as same-strain correlated poorly with all three clinical assessments (range of percent agreement, 50% to 57%; range of kappa statistic, 0.01 to 0.15). There were both false-positive and false-negative errors. Patients with three or more positive blood cultures were more likely to have same-strain bacteremia than those with only two positive cultures [11 of 15 (73%) vs 8 of 27 (30%), P = 0.006]. Pulsed-field gel electrophoresis was more discriminating than arbitrary primed PCR (percent agreement, 83%; kappa, 0.67). CONCLUSION: Molecular typing correlated poorly with clinical criteria for true bacteremia, suggesting either that true bacteremias are frequently the result of multiple strains or that the commonly used clinical criteria are not accurate for distinguishing contamination from true bacteremia. Vancomycin treatment of clinically defined coagulase-negative staphylococcal bacteremia may frequently be unnecessary.     

Predictors of bacteremia and gram-negative bacteremia in patients with sepsis. The Veterans Affairs Systemic Sepsis Cooperative Study Group.

BACKGROUND--We analyzed data from the Department of Veterans Affairs trial of steroid therapy for systemic sepsis to identify predictors of bacteremia and gram-negative bacteremia. METHODS--Of the 2568 patients screened for entry in the trial, 465 met the following criteria: presence of four of seven clinical signs of sepsis; blood cultures at the time of screening; and complete data on nine clinical parameters. The multivariate logistic regression model was used to identify predictors of bacteremia and gram-negative bacteremia. Predicted probabilities of having these types of infections were calculated using the identified predictors. Patients were then classified into groups with and without bacteremia (and gram-negative bacteremia) based on the predicted probability. Misclassification error rates were calculated for each method of categorization by comparing the true with the predicted grouping of patients. RESULTS--Three factors were independently predictive of bacteremia and gram-negative bacteremia: elevated temperature, low systolic blood pressure, and low platelet count. Using these three factors, classification methods were identified that predicted blood infection better than chance, but misclassification was also high. For predicting bacteremia, the maximum predicted positive rate was 83%, with a specificity of nearly 100% and a sensitivity of only 5%. For predicting gram-negative bacteremia, the maximum predicted positive accuracy was 100%, with a specificity also of 100% and a sensitivity of almost 0%. CONCLUSIONS--Using simple clinical parameters, we could not predict either bacteremia or gram-negative bacteremia with sufficient accuracy to be clinically meaningful; however, our approach represents a step in the direction of forecasting the bacterial organism responsible for sepsis in advance of culture results.     

Outcome of bacteremia and fungemia in paediatric oncology patients.

OBJECTIVE: To determine the outcome of paediatric oncology patients with positive blood cultures. DESIGN: Retrospective chart review. SETTING: Tertiary care hospital. POPULATION STUDIED: Oncology patients up to 17 years of age with positive blood cultures from January 1, 1994 to March 31, 1999. MAIN RESULTS: There were 121 episodes of positive blood cultures in 76 patients. Seventeen episodes were excluded because blood cultures were contaminated. Of the organisms grown from the remaining episodes, 63% were Gram-positive organisms, 23% were Gram-negative organisms, 3% were fungal and 11% were mixed. There were 13 episodes with pure or mixed isolates of Staphylococcus aureus, of which nine occurred within 14 days of the placement of a new central venous tunnelled catheter. Central venous tunnelled catheters were retained in 76 of the 102 episodes when they were present. There were two relapses, and four children were admitted to the intensive care unit with septic shock, but all survived. CONCLUSIONS: The outcome was excellent with the current management of possible bacteremia in paediatric oncology patients, but the high incidence of S aureus bacteremia suggests that empirical antibiotics should be altered if sepsis is suspected within 14 days of the placement of a central venous catheter.     

Clonal Diversity in Episodes with Multiple Coagulase-Negative Staphylococcus Bloodstream Isolates Suggesting Frequent Contamination

Abstract Background:   Coagulase-negative Staphylococci (CoNS) are frequently recovered from blood cultures, which may indicate contamination or true bacteremia. Patients and Methods:   CoNS isolates recovered from patients with episodes of two or more blood cultures positive for CoNS within 24 h were typed by both pulsed-field gel electrophoresis (PFGE) and speciation. Results:   PFGE typing of 94 CoNS isolates recovered from episodes with two or more positive blood cultures for CoNS within 24 h discriminated 35 strain clusters. The CoNS isolates were unrelated in 15 (39%) of 38 episodes, suggesting contamination. Sensitivity and specificity of CoNS speciation compared to PFGE was 96% and 67%, respectively. Clonal and species diversity differed between hospital areas. Conclusion:   Contamination may frequently be present even in the setting of the recovery of CoNS from two or more blood culture sets within 24 h. Speciation of CoNS bloodstream isolates is rapid and may improve patient care as well as reduce unnecessary antibiotic use.     

Febrile inpatients

The so-called “fever work-up” is time-consuming and costly. The authors examined the practices of medical house officers in obtaining blood cultures, an important part of this evaluation, as well as the ability of these physicians to predict bacteremia in febrile patients. They studied all 344 medical inpatients who experienced episodes of fever during two 30-day periods, as well as all 50 cases of bacteremia detected during these and two additional 30-day periods. House officers drew blood for culture within one day after the onset of fever in 52% of fever episodes. In 20% of these episodes only one set of cultures (representing one venipuncture) was obtained. House officers estimated the likelihood of bacteremia to be 20% or less in 15 of 40 bacteremic patients. They failed to obtain blood cultures promptly in 10% of bacteremic episodes and in 27% of episodes where the cause of fever was a nonbacteremic bacterial infection. They obtained prompt blood cultures in only a bare majority of febrile episodes, frequently underestimated the likelihood of bacteremia, and inadequately sampled blood for bacteremia. In this study, clinical judgment was not an adequate substitute for routinely obtaining blood cultures for febrile medical inpatients. Received from the Divisions of General Medicine and Primary Care, Consolidated Department of Medicine, Beth Israel Hospital and Brigham and Women’s Hospital; The Charles A. Dana Research Institute and the Harvard — Thorndike Laboratory, Beth Israel Hospital; The Henry J. Kaiser Fellowship Program; Harvard Medical School, Boston, Massachusetts; The Department of Medicine, Cambridge Hospital, Cambridge, Massachusetts; and the Department of Medicine, Montefiore Hospital, New York, New York. Supported in part by grants from the National Center for Health Services Research (HS 02063 and HS 04066), and by a grant from the Henry J. Kaiser Family Foundation.     

Staphylococcus aureus in a single positive blood culture: causes and outcome

Single positive culture was encountered in 61/235 patients (26%) with Staphylococcus aureus in blood culture over a 2-y period. It represented either true bacteremia (n = 52 cases; 85.2%) or contamination (n = 9; 14.8%). In comparison to cases with < or = 2 positive cultures, these patients did not have less severe disease or a lower incidence of complications.     

Molecular epidemiology of gram-negative bacteremia.

We did pulsed field gel electrophoresis (PFGE) and antibiotic susceptibility testing on 202 gram-negative isolates obtained from blood cultures between 1 January 1989 and 31 December 1993. Seventy-eight patients had at least two gram-negative isolates of the same species recovered from blood drawn one or more days apart and met the other study criteria. Twenty patients had only 1 bloodstream infection, 48 patients had 1 recurrence of bacteremia, and 10 patients had > 1 recurrence of bacteremia. Of 80 recurrences of bacteremia, 52 (65%) were relapses and 28 (35%) were reinfections. Seventy-eight percent of the episodes of bacteremia occurring < or = 300 days apart were relapses, and 100% occurring > 300 days apart were reinfections (P < .001). Organisms causing recurrent bacteremia were not more resistant than those causing initial episodes. In conclusion, most episodes of recurrent gram-negative bacteremia were relapses. Relapses and reinfections could not be distinguished only by the length of time between episodes or by antimicrobial susceptibility patterns.     

Blood cultures in ambulatory patients who are discharged from emergency with community-acquired pneumonia.

OBJECTIVES: To determine the factors that predict whether or not ambulatory patients with community-acquired pneumonia (CAP) treated in an emergency room (ER) setting will have blood cultures drawn and the factors that predict a positive blood culture. METHODS: Prospective observational study of all patients with a diagnosis of CAP, as made by an ER physician, who presented to any of seven Edmonton-area ERs over a two-year period. RESULTS: Seven hundred ninety-three (19.2%) of 4124 patients with CAP had blood cultures drawn. The site-specific blood culture rates ranged from 7.8% to 25% (P<0.001); 41 of 793 (5.1%) were positive. Streptococcus pneumoniae accounted for 58.5% of the isolates while Staphylococcus aureus and Escherichia coli each accounted for 14.6%, or six patients each. Only two of the 24 patients with S pneumoniae bacteremia were subsequently admitted to hospital while all six of the patients with S aureus were admitted. Only one of the six patients with E coli bacteremia was treated at home. No factors were predictive of positive blood cultures on multivariate analysis. CONCLUSIONS: Physicians are selective in ordering blood cultures on patients with ambulatory pneumonia who present to an ER, and the positivity rate of 5.1% is quite high. No factors are predictive of positive blood cultures on multivariate analysis, thus clinical judgment has to prevail in the decision to perform blood cultures. Breakthrough bacteremia can occur with microorganisms susceptible to the antibiotics that the patient is receiving.     

Low Rate of Clinical Consequences Derived from Results of Blood Cultures Obtained in an Internal Medicine Emergency Department

Abstract Background: Blood cultures detect bacteremia in individual patients and help define local pathogen and resistance spectra. At the same time, the benefits of blood culture results in the management of individual patients – and therefore their cost–effectiveness – are disputed. Patients and Methods: During 1 calendar year, we conducted a prospective study of emergency department admissions with blood culture draws and at least a 3–day hospitalization afterwards. We prospectively surveyed treating physicians on usefulness of blood culture results for patient management. Results: 428 diagnostic episodes (emergency visits) involving 390 patients occurred during the study period from 10/2002 to 10/2003. The analysis included 188/428 (44%) episodes with blood culture draws performed according to the predefined clinical standard where patients were hospitalized with sufficient duration. Absence of therapeutic consequences in response to blood culture results was reported for 138/142 (97%) of episodes with negative blood culture results, for 16/21 (76%) with blood culture results positive only for skin flora, and for 14/25 (56%) of episodes with blood cultures positive for obligate pathogens. Treating physicians regarded the blood culture results necessary for clarifying the etiology in 34/188 (18%) episodes, and rated blood culture results necessary for their therapeutic decisions in 29/188 (15%) episodes. Conclusion: Negative blood culture results rarely changed the management of medical inpatients. Our study suggests that in settings with broad–spectrum empirical antibiotic therapy positive blood culture results for obligate pathogens trigger adjustment of the antibiotic therapy in only about half of instances. Many blood cultures drawn in the emergency department where considered unnecessary by ward physicians. Guidelines for preventing unnecessary blood culture draws are warranted in order to increase the rate of their meaningful clinical consequences for medical inpatients initially treated with broad–spectrum empirical antibiotics. This paper is dedicated to the founders of the Walter Marget Foundation, D. Adam and F. Daschner, in gratitude for their support of the training in infectious diseases.     

Survey of blood cultures from five community hospitals in south-western Sydney, Australia, 1993–1994

Background : Blood culture results have profound implications for patients. Comprehensive overviews of blood cultures have been uncommon, and focused on tertiary referral hospitals.
Aim : To present a review of blood culture results from a laboratory servicing community hospitals in Sydney, Australia.
Methods : Retrospective chart review of patients with positive blood cultures from 1 June 1993 to 31 May 1994.
Results : During the survey period there were 107,382 hospital admissions; 12,109 blood culture sets from 9292 patients were processed. Of these 1197 sets were positive, representing 974 febrile episodes in 923 patients. There were 476 episodes of contamination. Of the episodes of true bacteraemia, Escherichia coli was isolated in 139, Staphylococcus aureus in 91 (22 methicillin-resistant), other enterobacteriaceae in 60, and Streptococcus pneumoniae in 51. The diagnoses attributable to bacteraemia included intravenous catheter-related sepsis (122 episodes), urinary tract infection (88), bacteraemia from unknown source (79), intra-abdominal and biliary sepsis (91), pneumonia (35), and meningitis (21). Sixty-eight patients died directly due to bacteraemia. Multivariate analysis showed underlying disease (OR 3.97) or shock (OR 28.1) predicted death. Blood cultures confirmed clinical diagnoses in 258 episodes, but made a de novo diagnosis in 205 episodes.
Conclusions : This study describes the clinical and laboratory features of bacteraemias occurring in smaller public hospitals, as distinct from tertiary referral centres. It demonstrated that intravenous catheter-related sepsis was very common in smaller hospitals. The clinical diagnosis was frequently confirmed, and a de novo diagnosis was often established by a positive blood culture. Unfortunately nearly half the positive blood cultures represented contamination.     

Non-O1 Vibrio cholerae Bacteremia in Patients with Cirrhosis: 5-yr Experience from a Single Medical Center

Objectives: To assess the clinical features and susceptibility of cirrhotic patients to non-01 Vibrio cholerae bacteremia and to provide our therapeutic experiences in this rare and highly lethal infection. Methods: Twenty-eight blood culture isolates of non-01 V. cholerae were identified by our clinical microbiology laboratory between July 1989 and June 1994. Patients with underlying cirrhosis and the aforementioned bacteremia were retrospectively reviewed. Results: Twenty-one cirrhotic patients (16 male, five female; mean age, 50.9 yr; range 28–67 yr) were identified and classified as Child B (6 cases) and Child C (15 cases). Bacteremic episodes occurred most often from March to September. Seafood ingestion (seven cases) and seawater exposure (two cases) were risk factors, but nosocomial infections were also noted in six cases. Presenting symptoms and signs included ascites (95.2%), fever (81%), abdominal pain (52.4%), diarrhea (33.3%), and cellulitis with bullae Formation (19%). Concurrent spontaneous bacterial peritonitis was determined in 10 cases, seven with positive ascites cultures. Antibiotic therapy (either cephalothin with gentamicin or ceftriaxone alone) cured most of the bacteremic episodes. The overall case-fatality rate was 23.8%, hut 75% of the deaths were observed in patients with skin manifestation. Conclusions: Patients with decompensated cirrhosis are susceptible to non-01 V. cholerae bacteremia and should not ingest raw sea food or expose skin wounds to salt water. A high index of suspicion and early administration of antibiotics may lower the mortality rate.     

Routine use of anaerobic blood cultures: are they still indicated?

PURPOSE: To determine the number of patients with bacteremia and fungemia and to evaluate the utility of routine anaerobic blood cultures as part of the work-up for suspected bacteremia. SUBJECTS AND METHODS: Retrospective review of microbiology data followed by selective chart review at a university-affiliated Veterans Affairs Medical Center. We determined the number of bacterial blood cultures drawn from January 1, 1994, to December 31, 1996, and the number of anaerobic, aerobic, and fungal isolates. Chart reviews were then performed on all patients with a positive anaerobic result.RESULTS: There were 6,891 sets of blood cultures processed through the laboratory, yielding 1,626 patients with positive results. Anaerobic isolates were recovered from 36 patients (2.2%) in 48 bottles. Aerobic isolates were recovered from 1550 patients (95.3%), and fungal isolates were recovered from 40 patients (2.5%). Seven patients (0.4%) had true anaerobic bacteremia. All seven patients had an obvious source of anaerobic infection that was known or suspected before the cultures were drawn. Antibiotic changes were made in four of these patients after the positive anaerobic results were known. Antibiotic changes led to clinical improvement in one patient. CONCLUSIONS: Routine use of anaerobic blood cultures rarely results in clinically important diagnostic or therapeutic benefits, based on the low incidence of anaerobic bacteremia in patients who are not at increased risk. Anaerobic blood cultures should be selectively ordered in patients at risk for anaerobic infections.     

Incidence of bacteremia in transesophageal echocardiography: a prospective study of 140 consecutive patients

The incidence of bacteremia related to transesophageal echocardiography was studied in 140 consecutive patients (71 women and 69 men with a mean age of 53.7 +/- 15 years). Thirty-four patients had one or more prosthetic heart valves. Blood cultures were obtained from each patient through separate venipuncture sites immediately before and after transesophageal echocardiography. An additional late blood culture was obtained in 114 patients 1 h later. The skin was cleaned with povidone-iodine and venipunctures were performed with separate butterfly needles with use of sterile gloves and drapes. Blood samples were drawn into separate syringes, transferred to aerobic and anaerobic culture bottles and processed with use of a semiautomated system. The overall incidence of blood cultures positive for bacteremia was 2% (8 of 394 bottles) and all positive cultures grew in a single blood culture bottle. Positive cultures occurred in 4 (1.4%) of 280 bottles before the procedure, in 2 (0.7%) of 280 bottles immediately after the procedure and in 2 (0.9%) of 228 late (1-h) blood culture bottles. Bacterial isolates were coagulase-negative staphylococci (n = 5), Propionibacterium (n = 2) and Moraxella (n = 1). All were considered contaminants. Mean endoscopic time in these patients was not significantly different from that in the other patients. Follow-up of patients with a blood culture positive for bacteremia revealed no clinical evidence of systemic infection. It is concluded that 1) the incidence of bacteremia related to transesophageal echocardiography is very low, and 2) the incidence of blood cultures positive for bacteremia after transesophageal echocardiography is indistinguishable from the anticipated contamination rate.     

Two rules for early prediction of bacteremia

BACKGROUND: Two rules (model 1 and model 2) were previously derived and prospectively validated at the same institution to predict the likelihood of bacteremia. The objective of the present study was to test and compare the performance of the rules in patients admitted to two sites of inpatient care: a university hospital and a community hospital. METHODS: Clinical and laboratory data (including the variables contained in the two models) were collected within 24 hours in all patients admitted to the Department of Medicine of the Beilinson Medical Center, a university hospital in central Israel, and Emek Hospital, a community hospital in northern Israel, because of an acute infectious disease. The scores of the models were compared with the results of blood cultures. RESULTS: The percentage of bacteremia was 15% in the university and 18.5% in the community hospital. The area under the receiver-operating characteristic curve was 0.560.04 SE for model 1, and 0.670.04 SE for model 2 in the university hospital; and 0.590.05 SE versus 0.630.04 SE, respectively, in the community hospital. At the best calibration, model 1 defined low-risk groups of 205 patients in the university hospital, and 66 patients in the community hospital, with prevalences of bacteremia of 13% and 15%. The high-risk groups defined by model 1 had prevalences of 30% and 32%. Model 2 defined low-risk groups with prevalences of bacteremia of 7% (8 of 114) and 8% (6 of 76); and high-risk groups with percentages of 29% and 38%. CONCLUSIONS: The overall accuracy of the two models deteriorated significantly. Both models defined groups at high risk of bacteremia, but the percentages of bacteremia and of death in the low-risk groups do not encourage withholding blood cultures in these patients. The failure of the two models points toward the need for external validation, and for monitoring performance of prediction models over time.     

Incidence of bacteremia in cirrhotic patients undergoing upper endoscopic ultrasonography

Background

The incidence of bacteremia after endoscopic ultrasonography (EUS) or EUS-guided fine-needle aspiration (EUS-FNA) is between 0% and 4%, but there are no data on this topic in cirrhotic patients.

Aim

To prospectively assess the incidence of bacteremia in cirrhotic patients undergoing EUS and EUS-FNA.

Patients and methods

We enrolled 41 cirrhotic patients. Of these, 16 (39%) also underwent EUS-FNA. Blood cultures were obtained before and at 5 and 30 min after the procedure. When EUS-FNA was used, an extra blood culture was obtained after the conclusion of radial EUS and before the introduction of the sectorial echoendoscope. All patients were clinically followed up for 7 days for signs of infection.

Results

Blood cultures were positive in 16 patients. In 10 patients, blood cultures grew coagulase-negative Staphylococcus, Corynebacterium species, Propionibacterium species or Acinetobacterium Lwoffii, which were considered contaminants (contamination rate 9.8%, 95% CI: 5.7–16%). The remaining 6 patients had true positive blood cultures and were considered to have had true bacteremia (15%, 95% CI: 4–26%). Blood cultures were positive after diagnostic EUS in five patients but were positive after EUS-FNA in only one patient. Thus, the frequency of bacteremia after EUS and EUS-FNA was 12% and 6%, respectively (95% CI: 2–22% and 0.2–30%, respectively). Only one of the patients who developed bacteremia after EUS had a self-limiting fever with no other signs of infection.

Conclusion

Asymptomatic Gram-positive bacteremia developed in cirrhotic patients after EUS and EUS-FNA at a rate higher than in non-cirrhotic patients. However, this finding was not associated with any clinically significant infections.