Bacterial Infection In Newborns Research Articles

Unexplained neonatal jaundice as an early diagnostic sign of urinary tract infection

Hyperbilirubinemia is one of the presenting signs of bacterial infection in newborns, and the association of neonatal jaundice with urinary tract infection (UTI) has been particularly emphasized. The aim of this study was to determine the prevalence of UTI in asymptomatic jaundiced neonates younger than 4 weeks old. We prospectively evaluated 120 asymptomatic jaundiced and 122 healthy neonates without jaundice younger than 4 weeks old for UTI. Patients with UTI, defined as >10,000 colony-forming units of a single pathogen per milliliter urine obtained by bladder catheterization, were evaluated for sepsis. Of 120 asymptomatic jaundiced neonates with a mean age of 7 ± 4 days, 15 (12.5%) had a UTI. Of 122 healthy neonates, positive urine cultures from a urine bag were found in eight cases; however on reevaluation, urine cultures from bladder catheterization were negative. The most common pathogen isolated from the UTI cases was Klebsiella pneumoniae. Also, unconjugated hyperbilirubinemia was detected in all jaundiced patients with UTI. UTI was found in 12.5% of the asymptomatic jaundiced neonates with the onset of unconjugated hyperbilirubinemia in the first week of life. Therefore, we suggest that urine culture should be considered as a part of the diagnostic evaluation of jaundiced neonates older than 3 days with an unexplained etiology.

A group B streptococcal pilus protein promotes phagocyte resistance and systemic virulence

Group B Streptococcus (GBS) is a major cause of invasive bacterial infections in newborns and certain adult populations. Surface filamentous appendages known as pili have been recently identified in GBS. However, little is known about the role of these structures in disease pathogenesis. In this study we sought to probe potential functional role(s) of PilB, the major GBS pilus protein subunit, by coupling analysis of an isogenic GBS pilB knockout strain with heterologous expression of the pilB gene in the nonpathogenic bacterium Lactococcus lactis. We found the knockout GBS strain that lacked PilB was more susceptible than wild-type (WT) GBS to killing by isolated macrophages and neutrophils. Survival was linked to the ability of PilB to mediate GBS resistance to cathelicidin antimicrobial peptides. Furthermore, the PilB-deficient GBS mutant was more readily cleared from the mouse bloodstream and less-virulent in vivo compared to the WT parent strain. Strikingly, overexpression of the pilB gene alone in L. lactis enhanced resistance to phagocyte killing, increased bloodstream survival, and conferred virulence in a mouse challenge model. Together these data demonstrate that the pilus backbone subunit, PilB, plays an integral role in GBS virulence and suggests a novel role for gram-positive pili in thwarting the innate defenses of phagocyte killing.

Beyond the complete blood cell count and C-reactive protein: a systematic review of modern diagnostic tests for neonatal sepsis.

To systematically review the accuracy of modern laboratory tests for the diagnosis of serious bacterial infection in newborns. The MEDLINE, EMBASE, and Cochrane Library databases were searched using the keywords newborn, infection, sepsis, and diagnosis. We included studies published from 1995 through 2001 that included infants younger than 90 days with proven bacterial growth in a sample from a sterile site. Whenever possible, relevant data were extracted to calculate likelihood ratios (LRs) for whether each test can diagnose a serious bacterial infection. Two independent reviewers selected and reviewed the articles (interobserver agreement, kappa = 0.80). All disagreements were resolved by consensus. Of the 137 citations we retrieved, 37 articles met the inclusion criteria; 17 studies, evaluating 11 different tests, met the highest methodological criteria. The most commonly evaluated test was interleukin 6 (IL-6) level (n = 7 studies). The remaining tests were each evaluated in no more than 3 studies. Positive LRs ranged from 1.5 to infinity. Six individual tests examined in 8 studies had LRs of more than 10 (range, 12.5- infinity ). Combined tests also had a wide range of LRs (3.4-9.9). All studies were performed in single medical centers and had small sample sizes, making recommendations according to gestational age criteria difficult. We found few methodologically rigorous studies of the accuracy of laboratory tests for the diagnosis of bacterial infection in newborns; in a significant proportion of studies, the accuracy of the tests could not be independently determined because of a lack of adequate data. There was marked heterogeneity in sample selection and cutoff levels for diagnosis of neonatal sepsis. A few tests showed promising accuracy, but there are insufficient data to support their confident use as clinical tools.

Infections bactériennes de la peau et des tissus mous chez le nouveau-né

Infections bactériennes de la peau et des tissus mous chez le nouveau-né

Diagnostic potential of neutrophil elastase inhibitor complex in the routine care of critically ill newborn infants

It has been suggested that determination of the neutrophil elastase alpha1-proteinase inhibitor complex (E-alpha1PI) improves the diagnosis of bacterial infection in newborns. We evaluated the use of E-alpha1PI measurements in 143 newborns, consecutively admitted to a tertiary intensive care unit, employing a new random access assay and a sampling procedure that minimises post-collection artefacts. The 95% range for noninfected newborns was 20-110 microg/l up to the 5th day of life and 20-85 microg/l thereafter. The sensitivity as to the diagnosis of culture-proven bloodstream infection was 80% for E-alpha1PI, 86% for the immature to total neutrophil ratio, 64% for C-reactive protein and 37% for the total white blood cell count. The corresponding specificity amounted to 97%, 85%, 85% and 86%, respectively. E-alpha1PI increases preceded elevations of C-reactive protein by 18 h. Like C-reactive protein, E-alpha1PI levels did not distinguish between bloodstream infection and non-bacterial inflammatory responses. Results of E-alpha1PI became available within 1 h of collection and usually 2-3 h before manual leucocyte counts. Determination of neutrophil elastase alpha1-proteinase inhibitor levels yields diagnostic advantages comparable to those of manual differential counts but provide faster turnaround times.

Bacterial Infection in Newborns with Respiratory Distress: The Role of Group B β-Hemolytic Streptococcus (GBS) in Brazilian Newborns. 1333

Respiratory distress (RD) within the first days of life is a common sign of early-onset bacterial infection. The bacterial etiology of early-onset neonatal infection varies from one population to another. Gram-positive organisms such as GBS are an infrequent cause of neonatal infection in some tropical countries. In Brazil, there role of GBS in neonatal infection is unknown. The aim of this study was to determine the frequency of bacterial infection in Brazilian newborns with RD considering the relative distribution of each pathogen. All of 261 consecutively admitted newborns who had RD within 96 hours of life (excluding aspiration syndromes, transient tachypnea, cardiac disease or congenital anomalies) were evaluated. Before the use of antibiotics, a blood culture, a urine culture, a latex test to detect GBS antigen in concentrated urine samples and leukocyte counts were done. Infants with positive blood cultures for pathogenic non-contaminant organisms were considered to have a confirmed infection. A true infection with S. epidermidis was considered in the presence of suggestive clinical and laboratory evidence. Infants with negative blood culture and positive GBS antigen urine tests with negative urine culture were considered to have presumed infection by GBS if clinical and laboratory signs were present. The newborns studied had a median gestational age of 32 weeks and a median birth weight of 1400 g. Screening of pregnant women for GBS colonization was not done. Only 3 of the 37 (8.1%) mothers of these newborns received antibiotics prior to delivery. Overall, there were 37/261 (14.2%) newborns with bacterial infection. The majority (78.4%) of neonatal infections were caused by Gram-positive organisms (29/37). The remaining 8 (21.6%) newborns were infected by Gram-negative organisms. GBS was the single most frequently detected pathogen among infected infants (35%) followed by S.epidermidis (13.5%), E. coli (10.8%), S. viridans (10.8%), other streptococci (10.8%), S. aureus (8.1%),H. influenzae (5.4%) and P. mirabilis (5.4%). Taking into account that GBS was detected in 5% (13/261) of all newborns with RD and that this organism has emerged as the major pathogen detected in this population, the implementation of regimens for prevention of GBS disease is strongly warranted.

Complement Deficiency and Neutrophil Dysfunction as Risk Factors for Bacterial Infection in Newborns and the Role of Granulocyte Transfusion in Therapy

The similarity in the susceptibility to bacterial infections of newborns and older patients with complement deficiencies, neutropenia, or neutrophil function defects has suggested that neutrophils and/or complement might also be defective in newborns. Although no individual element of the phagocytic host defense system is severely deficient, several partial deficiencies have been identified. These involve important amplification pathways of complement and neutrophil activation and may combine to cause significant decreases in phagocyte activity at sites of infection. Because of decreased specific antibody, initial activation of the classical complement pathway is decreased. Low levels of C3 and factor B decrease amplification by the alternative pathway and result in marked decreases in opsonization and generation of chemotactic activity from C5. There are also quantitative and qualitative neutrophil defects. The recent observations that newborns' neutrophils are relatively deficient in membrane expression of their major adherence protein/C3bi receptor help explain the decreased mobility and phagocytic activity of these cells. Thus, several partial deficiencies combine to cause severe impairments in delivery of neutrophils to sites of infection and contribute to the increased susceptibility of the newborn to infection.

C-reactive protein (CRP) in the diagnosis of bacterial infection in newborns: F. Larivière, M. Mason J.C. Forest, Linda Nadeau, Jeanne Pichette, C. Carrier. Services de biochimie et de néonatalogie, hôpital Saint-François d'Assise, Québec, G1L 3L5

C-reactive protein (CRP) in the diagnosis of bacterial infection in newborns: F. Larivière, M. Mason J.C. Forest, Linda Nadeau, Jeanne Pichette, C. Carrier. Services de biochimie et de néonatalogie, hôpital Saint-François d'Assise, Québec, G1L 3L5

The Treatment of Bacterial Infections in the Newborn Infant

There has been little apparent change in the overall incidence of systemic bacterial infection in newborns, though rates of disease differ among institutions and countries and patterns of causative organisms have shifted. Selected aspects of the clinical pharmacology of antimicrobials in newborns, present usage of agents for suspected systemic infection, the potential value of new therapies including a new generation of cephalosporins, and adjunctive therapies such as granulocyte transfusion, exchange transfusion, and immune globulins, are discussed.

Diagnosis of Bacterial Infections of the Newborn Infant

Early diagnosis of bacterial infection in newborns by identification of maternal and neonatal risk factors, improvement of laboratory methods, and preventive measures represents a challenge to clinician and investigator. The current status of diagnostic methods is discussed.

The Emergence of Group B Streptococci in Infections of the Newborn Infant

Because of a long association with mastitis in dairy cattle, the group B streptococcus (Streptococcus agalactiae) is an agent of considerable veterinary and economic importance (1). However, it has achieved medical prominence only within the past 15 years. Since 1962, well over 500 instances of group B streptococcal sepsis2 in newborn infants have been reported and many other cases, less stringently docu­ mented, have been described. In the United States, this organism is now the leading cause of serious bacterial infections in newborns (2-5) or at least shares this distinc­ tion with Escherichia coli (2). The incidence of group B streptococcal sepsis in several American and British centers has been estimated at between 1.3 and 3 per 1, 000 live births (2, 6-9). This chapter emphasizes clinical and relevant microbiological and epidemiologi­ cal aspects of newborn streptococcal infections. The more general subject of human disease related to group B streptococci was reviewed by Eickhoff in 1972 (10).