Experience of changing between signal and Bactec 9240 blood culture systems in a children's hospital

Optimum Time to Detection of Bacteria and Yeast Species with BACTEC 9120 Culture System from Blood and Sterile Body Fluids

The culture results of 4,807 blood and 383 sterile body fluid specimens received in our laboratory during a 54-month period, were analyzed to determine the time required for culture to become positive, time at which a culture could safely be considered negative, and the spectrum of isolated organisms. The specimens were processed by automated BACTEC 9120 culture system. A total of 1,677 clinically significant microorganisms were isolated. Gram positive and negative bacterial isolation rates were found to be 62.55% and 32.20%, respectively. Yeasts were recovered in 5.24%. False positivity rate was 1.5%. Clinically significant isolates recovered on day four and five were 97.81% and 99.88%, respectively. At day five, the sensitivity was 99.94% and negative predictive value 99.96%. Our data support a five-day incubation protocol for recovery of all clinically significant organisms with sensitivity reduced by 0.06%, when compared with a six-day protocol.

Distribution, optimum detection time and antimicrobial susceptibility rates of the microorganisms isolated from blood cultures over a 4-year time period in a Turkish university hospital and a review of the international literature

This study retrospectively examined 8986 blood cultures from patients over a 4-year time period in an eastern Turkish university hospital to determine the detection times and distribution of isolated microorganisms using the automated BACTEC 9050 and BACTEC 9120 systems. A total of 1914 (21.3%) blood cultures contained pathogenic microorganisms and 252 (2.8%) positive cultures were considered contaminated. Of all the cultures, 18 (0.2%) were false positives and 224 (2.5%) were false negatives. In cultures containing pathogenic microorganisms, Gram-positive and Gram-negative bacterial isolation rates were 436 (22.8%) and 1440 (75.2%), respectively, and yeasts (all Candida sp.) were found in 38 (2.0%) cultures. Coagulase-negative staphylococci occurred in 936 (48.9%) cultures and Staphylococcus aureus occurred in 302 (15.8%) cultures. The mean detection time for all of the pathogens was 21 h and Brucella spp were isolated within 10 days. This study helps in understanding the epidemiology of the region and in providing positive therapeutic approaches. A review of the international literature helps to place this understanding into a global context.

A 7-year study of bloodstream infections in an English children's hospital

Knowledge of the pattern of bloodstream infection (BSI) can help determine antibiotic prescribing policy and infection control procedures. Data on 2364 consecutive episodes of BSI at Birmingham Children's Hospital over 7 years were collected prospectively. A total of 1224 (51.8%) episodes were community-acquired, but only 281 (11.9%) were in previously healthy children. Intravascular devices (IVDs) were the most common source of infection, accounting for 48.9% of episodes. Gram-positive, gram-negative and anaerobic bacteria accounted for 66.2%, 31.3% and 0.4% of isolates, and 2.2% were yeasts. Coagulase-negative staphylococci, Staphylococcus aureus and enterococci accounted for over 50% of all isolates. Of these, only enterococci were predominantly hospital-acquired. Neisseria meningitidis was the most common cause of community-acquired BSI in previously healthy children. Of cases of meningococcaemia, 55.6% were diagnosed by PCR alone. Antibiotic resistance, especially in Enterobacteriaceae, S. aureus and enterococci, was more common than in earlier studies of BSI in children, and varied between specialties. The overall mortality rate directly attributable to infection was 2.4%, but was higher in neonates (6.2%) and in previously healthy children with community-acquired infections (5.3%).

CONCLUSION

Intravascular devices have emerged as the commonest source of bloodstream infection in children, leading to marked similarities in the species distribution of blood culture isolates across specialties other than General Paediatrics, and explaining the low overall mortality rate. Antibiotic resistance was found frequently in most commonly isolated pathogens, but differences between specialties suggest the existence of local risk factors, some of which might be amenable to infection control interventions.

Optimum detection times for bacteria and yeast species with the BACTEC 9120 aerobic blood culture system: evaluation for a 5-year period in a Turkish university hospital

We tracked and documented the time of positivity of blood cultures by using the BACTEC 9120 (Becton Dickinson Diagnostic Instrument Systems) blood culture system over a 5-year study period. A 7-day protocol of the incubation period was selected, and a total of 11156 blood cultures were evaluated. The clinically significant microorganisms (32.95%) were isolated in 3676 specimens. Gram-positive and -negative bacterial isolation rates were found to be 41.07 and 44.88%, respectively. Yeasts were found in 14.03% of all pathogens. Both the false-positivity and -negativity rates were very low (0.1 and 0.3%, respectively). The mean detection times for all of the pathogens were determined to be 19.45 h. Yeasts, nonfermentative gram-negative bacteria, and Brucella melitensis strains were isolated within 5 days. By taking these data into account, we decided to establish a 5-day-incubation protocol in our laboratory instead of the 7 days that are commonly used.

Use of anaerobically incubated media to increase yield of positive blood cultures in children

During a 3-year period we received 10024 blood samples for culture from pediatric patients. Overall 181 episodes of significant bacteremia were documented. During the study period we would have missed 35 (19%) of all significant episodes of pediatric bloodstream infections if we had not been using the anaerobically incubated blood bottle. Anaerobically incubated blood samples are also necessary in the pediatric population.

Enterococcal bacteremia in children: a review of seventy-five episodes in a pediatric hospital

BACKGROUND

Enterococcal bacteremia is being increasingly reported. Although there have been a number of recent studies of enterococcal bacteremia in adults, there are few studies involving children. We carried out a prospective study to determine the epidemiologic, clinical and laboratory characteristics of such bacteremia in children.

METHODS

Clinical and microbiologic data were recorded prospectively for all episodes of enterococcal bacteremia occurring during a 3-year period between January 1, 1995, and December 31, 1997.

RESULTS

Seventy-five episodes of enterococcal bacteremia occurring in children at our institution during a 3-year period were prospectively analyzed. Serious underlying disease was present in 67 (89.3%) episodes, and in 48 (64.%) episodes patients had received antibiotics during the 2 weeks preceding enterococcal bacteremia. Forty-seven (62.7%) episodes were nosocomial in origin and 26 (34.7%) were polymicrobial. Fifty (66.7%) episodes occurred in children 1 year old or less. A source of bacteremia was identified in 33 (44%) episodes, intravascular device being the most common identifiable source. Of the 73 isolates identified to species level, there were 36 Enterococcus faecium, 36 Enterococcus faecalis and one Enterococcus avium. In 60 (80%) episodes appropriate anti-enterococcal therapy was given. The overall mortality rate was 7.5%. Four clinical patterns of infection were identified: self-limited bacteremia, 16.0%; low grade sepsis with a favorable outcome after specific therapy, 65.3%; severe and prolonged infection associated with a high mortality rate, 14.7%; and fulminant neonatal sepsis in previously healthy babies, 4.0%.

CONCLUSION

Enterococcal bacteremia in children comprises a heterogeneous group. Bacteremias that are mild and self-limited and respond promptly to antibiotic therapy appear to be more common in children.