Umbilical cord blood culture in neonatal early-onset sepsis: a systematic review and meta-analysis

Utility of Anaerobic Blood Cultures in Neonatal Sepsis Evaluation

BACKGROUND

Clinicians variably obtain anaerobic blood cultures as part of sepsis evaluations in the neonatal intensive care unit (NICU). Our objective was to determine if anaerobic blood culture bottles yielded clinically relevant information by either recovering pathogens exclusively or more rapidly than the concurrently obtained aerobic culture bottle in the NICU.

METHODS

A retrospective cohort study of blood cultures obtained from infants admitted to the NICU from August 01, 2015 to August 31, 2023. Standard practice was to inoculate 2 mL of blood divided equally between an aerobic and an anaerobic culture bottle. We analyzed positive blood cultures where both aerobic and anaerobic bottles were obtained and compared pathogen recovery and time to positivity between the bottles.

RESULTS

During the study period, 4599 blood cultures were obtained from 3665 infants, and 265 (5.8%) were positive. Of these, 182 cultures were sent as aerobic-anaerobic pairs and recovered pathogenic organisms. Organisms were recovered exclusively from the anaerobic bottle in 32 (17.6%) cultures. Three organisms were obligate anaerobes; the rest were facultative anaerobes including Coagulase-negative staphylococci (40.6%), Escherichia coli (15.6%), and Staphylococcus aureus (15.6%). Cultures with exclusive recovery in the anaerobic bottle were more frequently obtained ≤3 days after birth, compared to other cultures (31.3% vs 15.3%, P = .03). When both bottles recovered the pathogen (n = 113), the anaerobic bottle had a shorter time to positivity in 76 (67.3%) cultures.

CONCLUSIONS

Including anaerobic culture bottles could lead to the identification of pathogens not recovered in the aerobic bottle, as well as earlier identification of pathogens.

Umbilical cord blood culture for early onset sepsis in preterm infants

BACKGROUND

Umbilical cord blood culture (UCBC) may have a diagnostic utility for early onset sepsis (EOS) detection in preterm infants. It may prevent sampling the newborn and collect a higher volume of blood for pathogenic identification.

METHODS

Retrospective analysis at a tertiary care center in Canada of preterm infants ≤ 34 0/7 weeks' gestation with UCBC taken at birth.

RESULTS

Of 505 admitted infants, 195 had UCBC. 170 UCBCs were negative; 44 of these had also negative neonatal blood culture (NBC). No infants with negative UCBC showed EOS symptoms in the first week of life. 25 UCBCs were positive: 18 were contaminants (all with negative NBC) and 7 were confirmed as EOS. 18 infants with UCBC contaminants remained asymptomatic. 7 EOS cases were identified, with varying bacteriological profiles; 5 displayed sepsis symptoms while 2 were asymptomatic. Risk of EOS increased with prolonged rupture of membranes.

CONCLUSIONS

UCBC effectively detected EOS establishing it as a method with possibly better diagnostic performance than NBC in high-risk neonates. Further studies are needed to improve UCBC technique and lower contamination rates.

IMPACT

Umbilical cord blood culture has a higher bacterial identification rate than peripheral venous blood culture for the early identification of early-onset sepsis in preterm infants. Umbilical cord blood cultures that showed no growth were reliable predictors of not developing early onset sepsis. Umbilical cord blood culture should be considered as part of the evaluation for early onset sepsis in the preterm infants.

Diagnostic Accuracy of Multiplex Polymerase Chain Reaction in Early Onset Neonatal Sepsis

Early onset neonatal sepsis is a significant contributor to neonatal morbidity and mortality. Although blood cultures remain the diagnostic gold standard, they detect pathogens in only a minority of suspected cases. This study compared the accuracy of blood cultures with a rapid multiplex PCR test. Newborns at risk of neonatal sepsis were prospectively screened as recommended per national guidelines. Evaluations included laboratory parameters (CrP, IL6, differential blood count), blood culture, and a molecular multiplex PCR test (ROCHE LightCycler SeptiFast®) identifying 20 common microbial agents. Blood samples were taken simultaneously from umbilical cord or venous sources on the first day of life. Of 229 infants included, 69% were born preterm. Blood culture and multiplex PCR sensitivity were 7.4% and 14.8%, respectively. Specificity, negative and positive predictive values between methods showed no significant variance, although multiplex PCR had more false positives due to contamination. The limited sensitivity of blood cultures for early onset neonatal sepsis is concerning. Despite quicker results, multiplex PCR does not enhance diagnostic accuracy or antibiotic therapy guidance, thus it cannot be recommended for this indication.

Potential of Molecular Culture in Early Onset Neonatal Sepsis Diagnosis: A Proof of Principle Study

Delay in the time-to-positivity of a peripheral blood culture (PBC), the gold standard for early onset neonatal sepsis (EOS) diagnosis, has resulted in excessive use of antibiotics. In this study, we evaluate the potential of the rapid Molecular Culture (MC) assay for quick EOS diagnosis. In the first part of this study, known positive and spiked blood samples were used to assess the performance of MC. In the in vivo clinical study, the second part of this study, all infants receiving antibiotics for suspicion of EOS were included. At initial EOS suspicion, a blood sample was collected for PBC and MC. MC was able to detect bacteria present in the spiked samples even when the bacterial load was low. In the clinical study, MC was positive in one infant with clinical EOS (Enterococcus faecalis) that was not detected by PBC. Additionally, MC was positive in two infants without clinical sepsis (Streptococcus mitis and multiple species), referred to as contamination. The other 37 samples were negative both by MC and PBC. MC seems to be able to detect bacteria even when the bacterial load is low. The majority of MC and PBC results were comparable and the risk for contamination and false positive MC results seems to be limited. Since MC can generate results within 4 h following sampling compared with 36-72 h in PBC, MC may have the potential to replace conventional PBC in EOS diagnostics in order to guide clinicians on when to discontinue antibiotic therapy several hours after birth.

Group B Streptococcus Early-Onset Disease: New Preventive and Diagnostic Tools to Decrease the Burden of Antibiotic Use

The difficulty in recognizing early-onset neonatal sepsis (EONS) in a timely manner due to non-specific symptoms and the limitations of diagnostic tests, combined with the risk of serious consequences if EONS is not treated in a timely manner, has resulted in a low threshold for starting empirical antibiotic treatment. New guideline strategies, such as the neonatal sepsis calculator, have been proven to reduce the antibiotic burden related to EONS, but lack sensitivity for detecting EONS. In this review, the potential of novel, targeted preventive and diagnostic methods for EONS is discussed from three different perspectives: maternal, umbilical cord and newborn perspectives. Promising strategies from the maternal perspective include Group B Streptococcus (GBS) prevention, exploring the virulence factors of GBS, maternal immunization and antepartum biomarkers. The diagnostic methods obtained from the umbilical cord are preliminary but promising. Finally, promising fields from the newborn perspective include biomarkers, new microbiological techniques and clinical prediction and monitoring strategies. Consensus on the definition of EONS and the standardization of research on novel diagnostic biomarkers are crucial for future implementation and to reduce current antibiotic overexposure in newborns.

Neonatal Early Onset Sepsis (EOS) Calculator plus Universal Serial Physical Examination (SPE): A Prospective Two-Step Implementation of a Neonatal EOS Prevention Protocol for Reduction of Sepsis Workup and Antibiotic Treatment

Current neonatal early-onset sepsis (EOS) guidelines lack consensus. Recent studies suggest three different options for EOS risk assessment among infants born ≥35 wks gestational age (GA), leading to different behaviors in the sepsis workup and antibiotic administration. A broad disparity in clinical practice is found in Neonatal Units, with a large number of non-infected newborns evaluated and treated for EOS. Broad spectrum antibiotics in early life may induce different short- and long-term adverse effects, longer hospitalization, and early mother-child separation. In this single-center prospective study, a total of 3002 neonates born in three periods between 2016 and 2020 were studied, and three different workup algorithms were compared: the first one was based on the categorical risk assessment; the second one was based on a Serial Physical Examination (SPE) strategy for infants with EOS risk factors; the third one associated an informatic tool (Neonatal EOS calculator) with a universal extension of the SPE strategy. The main objective of this study was to reduce the number of neonatal sepsis workups and the rate of antibiotic administration and favor rooming-in and mother−infant bonding without increasing the risk of sepsis and mortality. The combined strategy of universal SPE with the EOS Calculator showed a significant reduction of laboratory tests (from 33% to 6.6%; p < 0.01) and antibiotic treatments (from 8.5% to 1.4%; p < 0.01) in term and near-term newborns. EOS and mortality did not change significantly during the study period.