A study of the role of multiple site blood cultures in the evaluation of neonatal sepsis

Abstract

Background: The optimal number of blood cultures needed to document sepsis in an ill neonate has undergone little critical evaluation. Multiple site cultures may improve pathogen detection if intermittent bacteremia occurs, or if a low density of bacteria is present in the blood. We hypothesized, however, that bacterial clearance is slower and bacteremia more continuous in septic neonates, so that a single site blood culture should be sufficient to accurately document true septicemia.Objective: To determine the need for multiple site blood cultures in the evaluation of neonates for sepsis.Design/Methods: Clinical data were prospectively collected for 216 neonates who had 269 pairs of blood cultures taken from two different peripheral sites for the evaluation of possible sepsis. A minimum of 1 ml of blood was obtained from the two peripheral sites within 15-30 min of each other. Based on prior retrospective data, we determined that 203 infants would need to have two site blood cultures to demonstrate a significant improvement in pathogen detection at an alpha of 0.05 and a beta of 0.20 (80%) power.Results: A total of 186 culture pairs were taken for evaluation of earlyonset sepsis in 186 neonates, while 83 pairs were drawn for evaluation of late-onset sepsis in 43 neonates. In all, 21 neonates from the late-onset group were evaluated more than once, and 12 neonates were evaluated for both early-and late-onset sepsis. In all, 20 (9.2%) of 216 neonates had 22 episodes of culture-proven sepsis at a median age of 18 days. All neonates with positive cultures had the same organism with a similar sensitivity pattern obtained from the two different peripheral sites. The other 196 study neonates had negative blood cultures from both sites. The single episode of early-onset sepsis was caused by Listeria monocytogenes, while all remaining episodes were late-onset with the following organisms: Staphylococcus epidermidis (7), methicillin-resistant Staphylococcus aureus (MRSA) (3), combined MRSA and Candida albicans (2), Candida albicans alone (2), late-onset Group B b-hemolytic Streptococcus (GBS) (2), Klebsiella pneumoniae (2), Enterococcus fecalis (1), Escherichia coli (1), and Serratia marcescens (1). Since no infant grew organisms from only one of the two sites, the data indicate that the diagnosis of sepsis would have been made correctly in all infants with a single site culture. Conclusions:Two site blood cultures for the initial evaluation of neonatal sepsis do not have a better yield in pathogen detection. Sepsis in neonates can be detected with no loss of accuracy with a single site blood culture with blood volume of X1 ml.

Can neutrophil responses in very low birth weight infants predict the organisms responsible for late-onset bacterial or fungal sepsis?

“…We have shown previously that a single-site blood culture should be sufficient to document sepsis in symptomatic infants, and is biologically plausible because young infants have high-colony-count bacteremia, the bacterial clearance is slower and the bacteremia more continuous in newborns with sepsis than in older patients. 16 The distribution of pathogens causing sepsis in a specific hospital unit is usually considered when empiric antibiotics are selected, but 'this approach assumes that all pathogens causing sepsis have equal likelihood of causing severe complications including meningitis and death,' 17,18 and that all antibiotics will have good cerebrospinal fluid penetration and be equally effective to treat meningitis, which is commonly associated with Gram-negative sepsis. In reality, when empiric antibiotics for late-onset sepsis are selected, one should be especially concerned about fulminant late-onset Gram-negative sepsis, in which infants die before pathogens and antibiotic susceptibilities have been identified, often in <48 h of onset of illness.…”

Epidemiological Evaluation of Blood Culture Patterns among Neonates Receiving Vancomycin

“…Yet, the optimal number of blood cultures and the ideal volume of blood needed to detect neonatal bacteremia are a matter of ongoing debate [27,28]. Multiple BC collection is especially problematic in neonates and often only one culture is (or can be) obtained [29]. Efforts have been made to enforce the clinical use of BC.…”

Role of multiple site blood cultures to document the clearance of bacteremia in neonates

“…Indications for the diagnostic blood cultures and the results of that study have been previously reported. 3 When diagnostic cultures were reported to be positive then central lines were removed, initial empiric antimicrobial therapy was altered according to the susceptibility of the isolate, and optimal antimicrobial drug concentrations were monitored. Details of the blood culture collection and skin cleansing methods have been summarized elsewhere.…”

“…Details of the blood culture collection and skin cleansing methods have been summarized elsewhere. 3 At the discretion of the attending neonatologist, beginning 48 to 72 h after initiation of antimicrobial therapy, follow-up blood cultures were drawn from two different peripheral sites with a minimum of 1.0 ml of blood from each site. Repeat cultures were obtained every 24 to 48 h until both blood cultures became negative.…”

“…3 However, once antimicrobial therapy is started, the blood bacterial density may be reduced rendering a single site blood culture insufficient to document either absence or presence of persistent bacteremia. 4 Proper documentation of clearance of bacteremia with blood culture is important because false-negative blood cultures could lead to a shorter course of antimicrobial treatment with potential adverse consequences.…”