Obtaining Blood Cultures Research Articles

Blood culture and respiratory syncytial virus identification in acute lower respiratory tract infection.

Even though the incidence of pneumonia in developed and developing countries is similar, the mortality is five times higher in developing countries. This study aimed to determine the prevalence of bacteremia in children with acute lower respiratory tract infection (LRTI) and relative contribution of respiratory syncytial virus (RSV). One hundred and one children under five years of age who attended a primary care level clinic with diagnosis of acute LRTI, were enrolled. Diagnosis and management of pneumonia were done according to the WHO guidelines. Two blood cultures were drawn at the time of admission. A nasopharyngeal sample was taken for detection of RSV by indirect immunofluorescence. Blood cultures were positive for pathogenic bacteria (Streptococcus pneumoniae, Haemophilus influenzae and Staphylococcus aureus) in three patients. The detection for RSV was positive in 24 patients (23.7%). The clinical and radiographic presentations were not significantly different between patients with and without RSV (p > 0.05). RSV is a common cause of LRTI in children younger than five years old. Blood cultures are not commonly positive in outpatients with acute LRTI. The practice of obtaining blood cultures in primary and secondary care clinics is not useful to guide the treatment of patients with community-acquired pneumonia.

Management of the young febrile child: a continuing controversy.

In 1975, Teele and colleagues1identified the risk factors for and occurrence of bacteremia in young febrile children presenting to a pediatric walk-in clinic. They found that 3.2% of children 4 weeks to 2 years of age were bacteremic and that the height of the temperature and white blood cell count were valuable predictors of bacteremia. The Teele report initiated a controversy regarding the management of young febrile children that continues today. Despite more than 20 years of research, the essential question remains unchanged—does obtaining a blood culture and initiating expectant therapy with oral or parenteral antibiotics prevent serious sequelae? In this issue of Pediatrics, Kramer and Shapiro2 argue that recently published guidelines for management of febrile children,3 which recommend blood culture and expectant therapy in infants and children with temperatures ≥39°C, are costly, intrusive, and do more harm than good.2 Good clinical practice guidelines have important attributes, including validity, reliability, and scheduled reviews.4 Since the publication of the fever guidelines there have been two developments that may affect their validity. First, there has been a dramatic reduction in the number of cases of meningitis, sepsis, and bacteremia specifically attributable to Haemophilus influenzae type B (Hib).5 The issue of expectant therapy and reduction in morbidity is now largely …

Occult bacteremia

The evaluation and management of patients with occult bacteremia is controversial. The purpose of this study was to define the prevailing practices in the emergency management of occult bacteremia. Short, anonymous surveys were mailed to all 517 members of the Section on Emergency Medicine at the American Academy of Pediatrics. Three hundred six (59%) of those surveyed returned completed questionnaires. Eleven different temperature cutoff points are used, and 105 (34%) consider occult bacteremia in patients with temperature above 39 degrees C. Seventeen different age intervals are used to define the patients at risk for occult bacteremia, and the age range three to 24 months is used by 173 (57%) of those surveyed. Complete blood cell count is the most commonly used screening test; it is routinely ordered by 225 respondents (74%). One hundred thirty-seven participants (45%) routinely obtain blood cultures in all patients at risk for occult bacteremia, whereas 111 (36%) use the clinical appearance (toxicity) of the patient to determine whether a blood culture should be drawn. One hundred sixty-one (53%) of those surveyed routinely administer antibiotics to toxic-appearing patients pending the results of the blood culture. Laboratory criteria are used by 135 (44%) in the decision whether to administer empiric antibiotics. Ceftriaxone is the most commonly used antibiotic; it is routinely administered by 230 respondents (75%). Twenty participants (7%) routinely admit all patients with Streptococcus pneumoniae, whereas 217 (71%) admit all patients with Haemophilus influenzae bacteremia and 234 (76%) admit all patients with Neisseria meningitidis bacteremia. We conclude that diversity exists in the evaluation and management of occult bacteremia.

Can bacteremia be predicted in surgical intensive care unit patients?

To determine which clinical features are associated with bacteremia in a SICU. To determine if infections are identified prior to bacteremia via culturing of other body fluids. To determine if antibiotic regimens are changed after the results of the blood culture were obtained. A retrospective, unit-based, case control study. A 10 bed SICU in a 552-bed, tertiary care and Level I Trauma center. All SICU patients with one or more positive blood cultures over a 2 year period (n = 24) were matched by diagnosis, procedure, and age to SICU patients with negative blood cultures (n = 48). Bacteremic and control patients had similar APACHE II scores though death was more likely in bacteremic patients (p < 0.05) and they had higher hospital charges (p < 0.02). There was no difference in any of the clinical variables studied (minimum and maximum temperature, maximum white blood cell count, minimum mean arterial blood pressure) between the bacteremic and control groups on the days leading up to and the day of the positive blood culture. Coincident infections of lung, bladder, wound, and central venous catheters were identified in 42% of bacteremic patients. The identification of organisms found in the blood had a direct impact on the antibiotic regimen of 54% of the bacteremic patients. A better screen for obtaining blood cultures in this SICU was not identified. If antibiotics are begun empirically before the results of blood cultures are known, the results of other body fluid cultures can be used to guide therapy initially. However, the data obtained from positive blood cultures was often helpful in changing empirical therapy. Therefore, blood cultures remain important diagnostic tools.

Clinical Issues of Blood Cultures

Dramatic changes in the methods of obtaining blood cultures in clinical practice have recently occurred owing to factors such as the rising number of patients at risk for infection, newer pathogens occurring in the bloodstream, widespread use of indwelling intravascular devices, and our improved ability to recover and identify microorganisms in blood. Guidelines for the proper practice of obtaining blood cultures are needed. Blood cultures must be obtained under sterile conditions when there is suspicion of bacteremia/ mycobacteremia, fungemia, or viremia. This review provides recent information on optimal blood culture practices during suspected bloodstream infection in hospitalized patients including those with continuous or intermittent bacteremia, patients with intravascular devices, and compromised hosts such as immunodeficient patients and those in intensive care units. The traditional two-bottle system of aerobic and anaerobic cultures continues to be helpful, although the frequency of anaerobic bacteremia has decreased. More recently, special culture/transport media have become available for the recovery of mycobacteria, fungi, and viruses. Communication between the clinician and laboratory personnel frequently aids in improving the yield from blood cultures. (Arch Intern Med. 1994;154:841-849)

Learning, experience, and self-assessment of competence of third-year medical students in performing bedside procedures.

Third-year medical students are expected to perform common bedside procedures as part of their daily ward activities, but there are few programs to teach these skills or document students' abilities to perform them. In addition to describing the clinical procedures course at the Medical College of Georgia School of Medicine, the purpose of this paper is to report how often students perform common bedside procedures during the third year of medical school, whether the number of times a procedure has been performed is indicative of self-perceived level of competence, and how useful the students find the procedures course for learning how to perform common procedures. In June 1991, the 163 entering third-year students participated in a two-day course in which they were taught universal precautions and provided specific step-by-step instructions for performing 16 clinical procedures. One year later, after the students had completed their third-year clerkships, they were asked to report the numbers of times they had performed the procedures during their clerkships, to provide self-assessments of their competency, and to indicate how helpful the course had been for learning clinical procedures. The association between the number of times the students reported performing a procedure and how competent they felt to perform the procedure was assessed using Kendall's tau coefficient. A total of 100 students returned completed questionnaires. Most of the students reported performing venipuncture, obtaining blood cultures, and scrubbing surgically more than five times, but they reported performing other procedures less frequently. For most procedures, self-assessment of competency correlated with frequency of performance. The procedures course was well received by students and instructors, based on both written evaluations and informal verbal feedback. Surprisingly, the students' self-reports indicated that many students performed procedures on patients infrequently. As expected, for most procedures there was a significant association between frequency of performance and self-assessed competency.

Mixed Bacteremia with Vibrio metschnikovii in an 83-year-old Female Patient

An 83-year-old woman suddenly fell ill and was admitted to the hospital on suspicion of a heart attack. After admission she developed high fever, chills and malaise. Vibrio metshnikovii and Staphylococcus hominis were isolated from 2 separately obtained blood cultures. One of the cultures also yielded Escherichia coli. The patient's condition improved rapidly after treatment with ampicillin intravenously. To our knowledge, this is the fourth reported case of V. metschnikovii bacteremia in humans.

Blood culture: Comparison of outcomes between switch-needle and no-switch techniques

Because blood culture is a common test at our institution, we hoped to save money and reduce the risk of needlestick injury by modifying our current technique for the preparation of culture specimens without increasing the risk of contamination. To compare the contamination rates of blood culture specimens obtained by the conventional method of switching to another sterile needle before inoculation with those of specimens obtained by a method without switching. Cross-over study. Department of Medicine of university hospital. Nursing personnel working in seven acute care medical wards in Siriraj Hospital, Bangkok, Thailand. From March to June 1991, participating nurses prepared blood culture specimens by means of both switch-needle and no-switch techniques in a cross-over study. All blood culture specimens were submitted to microbiology laboratory to determine the growth of microorganisms. Growth in a culture was considered to be "true positive" or "contamination" by predetermined criteria. Total number of blood culture specimens was 1619; of these, 813 were prepared by switch-needle technique and 806 were prepared by no-switch technique. The contamination rates were 7.6% and 8.3% for switch-needle and no-switch techniques, respectively (p = 0.61). The switch-needle technique may not be necessary for obtaining blood culture specimens unless the needle is obviously contaminated. The no-switch technique for the preparation of blood culture specimens is more convenient and less expensive; it also poses less risk of needlestick injury.

Management of asymptomatic, term gestation neonates born to mothers treated with intrapartum antibiotics

Intrapartum antibiotics are frequently administered to parturient women for suspected chorioamnionitis to treat infection in the mother and to prevent or treat infection in the baby. We sent a questionnaire to the 150 United States fellowship program directors in neonatology and pediatric infectious disease, focusing on recommendations for evaluation and therapy of apparently healthy, pretreated, term gestation infants. Eighty-three (55%) of the completed responses were analyzed. Sixteen (19%) respondents do no initial laboratory evaluation but simply observe the baby, 65 (78%) take a complete blood count as well as a platelet count, 59 (71%) obtain blood cultures, 41 (49%) check urine antigen for Group B Streptococcus (GBS) and 23 (28%) perform a lumbar puncture. Only 39% of respondents would begin antibiotic therapy for all pretreated infants. If the evaluation were unremarkable 65 directors would treat for less than or equal to 3 days. If only the urine GBS antigen were positive 47 would treat for greater than or equal to 7 days, while if an elevated immature neutrophil:total neutrophil ratio were the sole abnormality 19 would treat for greater than or equal to 7 days. Forty-four respondents thought that a combination of an elevated immature neutrophil:total neutrophil ratio and a positive urine GBS antigen should always be considered indicative of bacteremia. Given a different scenario, that of a mother treated with intrapartum antibiotics because of a positive cervical culture for GBS and a risk factor (e.g. temperature greater than or equal to 38 degrees C), 58 respondents would begin antibiotics. There is no consensus regarding management of pretreated, healthy appearing, term gestation neonates.

Utility of collecting blood cultures through newly inserted intravenous catheters

We prospectively examined the utility of obtaining blood cultures through newly inserted intravenous catheters in 99 children who required both a blood culture and placement of an intravenous catheter. Two blood cultures were collected from each patient, one through a freshly inserted intravenous catheter and another through a butterfly needle at a separate venipuncture site. A standardized technique of skin preparation with povidone-iodine was used. The rate of contamination was 1.0% (95% confidence intervals, 0 to 3.0%) for each method. Ten patients had blood cultures yielding true pathogens; in five of these bacteremic children, only one of two sets of blood cultures was positive. We conclude that blood cultures can be collected through freshly placed intravenous catheters without increasing the risk of contamination. These results also raise the possibility that obtaining two blood cultures instead of a single culture may improve the detection of bacteremia in children.

Detection of bloodstream infections in children

A critical responsibility of the clinical microbiology laboratory serving clinicians who care for infected children is accurate and timely detection of bacteremia. Blood culture protocols which are suitable for processing adult specimens are not necessarily the first choice for processing pediatric specimens. In this review, the following aspects of detection of bacteremia in children are covered: obtaining blood culture specimens from children, including skin disinfection, specimen volume and timing of specimen collection; the array of blood culture methods available, focusing upon conventional, radiometric, infrared spectroscopic and manometric broth cultures, as well as biphasic agar/broth and lysis direct plating techniques: the strengths and weaknesses of the various methods; and recommendations to laboratories for selection of a blood culture method based upon the laboratory's staffing level.

Occult Bacteremia in Children With Simple Febrile Seizures

Sir.—The association of bacteremia and febrile seizures described by Chamberlain and Gorman1in a recentAJDCarticle has been recognized at least since 1967, when two of three patients with pneumococcal bacteremia described by Belsey2presented with seizures. Five of 11 children with occult pneumococcal bacteremia described in 19703presented with seizures, and all had sterile cerebrospinal fluid. As Chamberlain and Gorman point out, obtaining blood cultures should always be considered for children with febrile seizures. We should recall that children with pneumococcal bacteremia, with or without seizures, who have sterile cerebrospinal fluid initially may go on to develop meningitis, while receiving oral or even parenteral antibiotics.2

Febrile inpatients: house officers' use of blood cultures.

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.

Clinical features and therapeutic interventions in 17 cases of Bacillus bacteremia in an immunosuppressed patient population.

We retrospectively examined episodes of Bacillus bacteremia at a hospital with a large proportion of immunosuppressed patients. Seventeen episodes in 9.5 years met our case definition: two of two bottles of one blood culture or one of two bottles of two or more separately obtained blood cultures drawn on the same date. During the same period, there were 59 additional episodes in which a single blood culture had only one of two bottles positive for Bacillus species. Only 2 of 59 such episodes resulted in recurrent bacteremia (3%), as compared with 5 of 17 episodes meeting our case definition (29%) (P = 0.004). In four of five episodes complicated by recurrent bacteremia and in which appropriate antibiotics were used, a Hickman-Broviac catheter was in place and was not removed. We suggest that our case definition permits the differentiation of infection from contamination based on outcome and that patients with Bacillus bacteremia have chronic venous catheters removed as well as receive antibiotic treatment.

Use of blood cultures in the emergency department

While the use of blood cultures to detect septicemia is a time-honored and valuable laboratory technique, guidelines for obtaining such cultures are vague. Several controversies exist regarding the utilization of blood cultures in the ambulatory setting, including when and on whom cultures should be obtained, how many cultures should be obtained, and how much blood should be obtained with each venipuncture. The guidelines have become slightly more confusing with the recognition of an entity known as occult bacteremia. A number of studies that bear relevance to these issues are reviewed. The utility of obtaining blood cultures in the ambulatory setting is examined, and guidelines are offered for obtaining blood cultures in adult and pediatric populations. Areas in which further research may be appropriate also are noted.

Prospective evaluation of the risk of bacteremia and the role of antibiotics in ERCP.

To determine the frequency of bacteremia associated with endoscopic retrograde cholangiopancreatography (ERCP), we obtained blood cultures before, during, and after ERCP in 51 consecutive patients. Patients with radiographically demonstrated abnormalities in pancreatic and/or biliary ducts were routinely given antibiotic therapy after ERCP. Bacteremia after successful cannulation of the papilla of Vater was observed in only one patient with multiple strictures of the main pancreatic duct. No episodes of acute febrile illness was observed in any patient during the 48-hour follow-up period after ERCP. Our observations suggest that the risk of bacteremia from ERCP is minimal, and that any possibility of sepsis after ERCP in patients with abnormal pancreatic or biliary ducts may be prevented by administering appropriate antibiotics after the procedure.

Nosocomial bacteremia in perspective: a community-wide study.

Prospective surveillance of 1,527 episodes of bacteremia in the four major hospitals serving a community of 300,000 revealed striking differences among the hospitals. The rate of community-acquired bacteremia ranged from 1.9 to 6.8 per 1000 discharges; the rate of nosocomial bacteremia ranged from 0.9 to 9.8 per 1000 discharges. Death rates attributed to nosocomial bacteremias varied among the hospitals by as much as 40-fold. Nosocomial bacteremias were less frequent at two community non-teaching hospitals than at two teaching hospitals. Although fewer blood cultures were obtained at the nonteaching hospitals, the ratio of blood cultures obtained to deaths attributed to bacteremic infection was highest at these hospitals, suggesting that physicians recognized the importance of obtaining blood cultures in critically ill patients. The potential usefulness of bacteremia surveillance is reviewed. It is suggested that hospitals serving a single community might constitute an appropriate unit for such surveillance.

Bacteremic Infection in Hemodialysis

This is a retrospective study of 133 episodes of bacteremic infection in 112 hemodialysis patients. The frequency of bacteremic infection was 9.5% in patients with chronic renal failure and 10.9% in patients with acute renal failure. In patients with acute renal failure, pneumonia and intra-abdominal abscess were the most frequent sources of septicemia. Sepsis was usually due to Gram-negative organisms and mortality was high. In patients with chronic renal failure, infection of the shunt or fistula was the most common cause, was frequently due to Staphylococcus organism, and had a more favorable survival rate. Gram-negative septicemia from a nonaccess source in patients with chronic renal failure was associated with a higher mortality. Bacterial endocarditis and septic pulmonary emboli occurred in 3.6% of septic episodes and 0.35% of patients at risk and had very low mortality. A low threshold for obtaining blood cultures and early antibiotic treatment are believed to be important in the treatment of bacteremic infections in patients undergoing long-term hemodialysis.

Use of the central venous pressure catheter to obtain blood cultures

The results of aerobic and anaerobic blood cultures obtained from a peripheral venopuncture and from the central venous pressure catheter were compared in critically ill patients admitted to the ICU to determine if pain and anxiety from multiple venopunctures could be alleviated while the physician's task is facilitated. The results were identical in 93.5% of the 92 comparisons. The discrepancies were evaluated and it was concluded that the method was easy, quick, and reliable. We recommend it as a suitable alternative to venopuncture.

Haemophilus Influenzae Infections in Adults: Report of Nine Cases and a Review of the Literature

Haemophilus influenzae is an aerobic pleomorphic gram-negative coccobacillus that requires both X and V factors for growth. It grows poorly, if at all, on ordinary blood agar unless streaked with Staph. aureus. It grows well on chocolate agar. Because this medium is often not used in culturing specimens from adults and because the organism may be overgrown by other bacteria, the frequency of H. influenzae infections has undoubtedly been seriously underestimated. This is aggravated by the failure of many physicians to obtain blood cultures in suspected bacterial infections and the failure of many laboratories to subculture them routinely onto chocolate agar. H. influenzae, along with Streptococcus pneumoniae, is a major factor in acute sinusitis. It is probably the most frequent etiologic agent of acute epiglottitis. It is probably a common, but commonly unrecognized, cause of bacterial pneumonia, where it has a distinctive appearance on Gram stain. It is unusual in adult meningitis, but should particularly be considered in alcoholics; in those with recent or remote head trauma, especially with cerebrospinal fluid rhinorrhea; in patients with splenectomies and those with primary or secondary hypogammaglobulinemia. It may rarely cause a wide variety of other infections in adults, including purulent pericarditis, endocarditis, septic arthritis, obstetrical and gynecologic infections, urinary and biliary tract infections, and cellulitis. Antimicrobial susceptibility testing is somewhat capricious in part from the marked effect of inoculum size in some circumstances. In vitro and in vivo results support the use of ampicillin, unless the organism produces beta-lactamase. Alternatives in minor infections include tetracycline, erythromycin, and sulfamethoxazole-trimethoprim. For serious infections chloramphenicol is the best choice if the organism is ampicillin-resistant or the patient is penicillin-allergic.