A comparison of two versus one blood culture in the diagnosis and treatment of coagulase-negative staphylococcus in the neonatal intensive care unit

Blood culture collection practices in NICU; A national survey

Background

Sepsis is the leading cause of mortality and morbidity in neonates. Blood cultures are the gold standard in diagnosing neonatal sepsis; however, there are currently no consensus guidelines for blood culture collection in neonates and significant practice variation exists in Neonatal Intensive Care Units (NICUs) globally.

Objective

To examine current practices in obtaining blood cultures in the evaluation of neonatal sepsis in NICUs across Canada.

Methods

A nine-item electronic survey was sent to each of the 29 level-3 NICUs in Canada, which are equipped to provide highly specialized care for newborns.

Results

Responses were received from 90% (26/29) of sites. Sixty-five percent (17/26) of sites have blood culture collection guidelines for the investigation of neonatal sepsis. Forty-eight percent (12/25) of sites routinely target 1.0 mL per culture bottle. In late-onset sepsis (LOS), 58% (15/26) of sites process one aerobic culture bottle, whereas four sites routinely add anaerobic culture bottles. In early-onset sepsis (EOS) in very low birth weight infants (BW <1.5 kg), 73% (19/26) of sites use umbilical cord blood, and 72% (18/25) use peripheral venipuncture. Two sites routinely collect cord blood for culture in EOS. Only one site applies the concept of differential time-to-positivity to diagnose central-line-associated bloodstream infection.

Conclusions

There is significant practice variation in methods used to obtain blood cultures in level-3 NICUs across Canada. Standardization of blood culture collection practices can provide reliable estimates of the true incidence of neonatal sepsis and help to develop appropriate antimicrobial stewardship strategies.

Determinants of morbidity and mortality related to health care-associated primary bloodstream infections in neonatal intensive care units: a prospective cohort study from the SEPREVEN trial

Background

Health care-associated primary bloodstream infections (BSIs), defined as not secondary to an infection at another body site, including central line-associated BSI, are a leading cause of morbidity and mortality in patients in neonatal intensive care units (NICUs). Our objective was to identify factors associated with severe morbidity and mortality after these infections in neonates in NICUs.

Methods

This ancillary study of the SEPREVEN trial included neonates hospitalized ≥2 days in one of 12 French NICUs and with ≥ 1 BSI during the 20-month study period. BSIs (all primary and health care-associated) were diagnosed in infants with symptoms suggestive of infection and classified prospectively as possible (one coagulase-negative staphylococci (CoNS)-growing blood culture) or proven (two same CoNS, or ≥1 recognized pathogen-growing blood culture). BSI consequences were collected prospectively as moderate morbidity (antibiotic treatment alone) or severe morbidity/mortality (life-saving procedure, permanent damage, prolonged hospitalization, and/or death).

Results

Of 557 BSIs identified in 494 patients, CoNS accounted for 378/557 (67.8%) and recognized bacterial or fungal pathogens for 179/557 (32.1%). Severe morbidity/mortality was reported in 148/557 (26.6%) BSIs. Independent factors associated with severe morbidity/mortality were corrected gestational age <28 weeks (CGA) at infection (P < .01), fetal growth restriction (FGR) (P = .04), and proven pathogen-related BSI vs. CoNS-related BSI (P < .01). There were no differences in severe morbidity and mortality between proven and possible CoNS BSIs. In possible BSI, S. epidermidis was associated with a lower risk of severe morbidity than other CoNS (P < .01), notably S. capitis and S. haemolyticus.

Conclusions

In BSIs in the NICU, severe morbidity/mortality was associated with low CGA at infection, FGR, and proven pathogen-related BSIs. When only one blood culture was positive, severe morbidity/mortality were less frequent if it grew with S. epidermidis compared to other CoNS. Further studies to help distinguish real CoNS BSIs from contaminations are needed.

Study registration

ClinicalTrials.gov (NCT02598609).

Double Blood Culture Policy Is More Effective Than Single In Neonatal Intensive Units

Aim: Blood culture (BC) sampling and antibiotic administration are common practices in Neonatal Intensive Care Units(NICUs). However, false positive BC results might affect clinician’s decision and lead to inappropriate antibiotic treatments. The aim of this study was to investigate the effect of double culture on clinical application. Material and Methods: The study was conducted retrospectively. The blood culture results of the patients admitted to the NICU between 2016-2019 were analyzed. Considering sepsis before 2017, we took only one sample from the patient. After this period, we started to take double blood cultures. Time frames of BCs were investigated to two groups as early and late onset sepsis fistly, and then subgroups as; a-) Group 1, BCs in the first 24 hours, b-)Group 2, between 24 to 72 hours, and c-)Group 3, after 72 hours. Results: Total of 1747 BC samples were taken in study. Majority of BCs were in Group 3(62%). Male/female ratio was 1.3:1. Staphylococcus Epidermidis(S. Epi) was major source for the contamination. But, by taking dBCs, we were able to eliminate most S.Epi contamination in Group 2 (11%vs.3%) and in Group 3(41%to14%). We were able to identify some resistant Gr(-) pathogens in one arm although the other arm was negative, by taking dBC. Conclusions: Our study indicates that dBC policy in NICUs could help to clinicians for judicious decision in antibiotic use and decrease unnecessary antibiotic exposure of infants. Also it could be enable to detect some highly pathogen microorganism easily. Key words: Newborn, Septicemia, Blood culture, Coagulase Negative Staphylococci, contamination

Dual-site blood culture yield and time to positivity in neonatal late-onset sepsis

OBJECTIVE

To determine whether culture yield and time to positivity (TTP) differ between peripheral and central vascular catheter-derived blood cultures (BCx) in neonatal intensive care unit (NICU) patients evaluated for late-onset sepsis.

DESIGN

Single-centre, retrospective, observational study.

SETTING

Level IV NICU.

PARTICIPANTS

The study included infants >72 hours old admitted to NICU in 2007-2019 with culture-confirmed bacteraemia. All episodes had simultaneous BCx drawn from a peripheral site and a vascular catheter ('catheter culture').

MAIN OUTCOME MEASURES

Dual-site culture yield and TTP.

RESULTS

Among 179 episodes of late-onset bacteraemia (among 167 infants) with concurrently drawn peripheral and catheter BCx, the majority (67%, 120 of 179) were positive from both sites, compared with 17% (30 of 179) with positive catheter cultures only and 16% (29 of 179) with positive peripheral cultures only. 66% (19 of 29) of episodes with only positive peripheral BCx grew coagulase-negative Staphylococcus, while 34% (10 of 29) were recognised bacterial pathogens. Among 120 episodes with both peripheral and catheter BCx growth, catheter cultures demonstrated bacterial growth prior to paired peripheral cultures in 78% of episodes (93 of 120, p<0.001). The median TTP was significantly shorter in catheter compared with peripheral cultures (15.0 hours vs 16.8 hours, p<0.001). The median elapsed time between paired catheter and peripheral culture growth was 1.3 hours.

CONCLUSION

Concurrently drawn peripheral and catheter BCx had similar yield. While a majority of episodes demonstrated dual-site BCx growth, a small but important minority of episodes grew virulent pathogens from either culture site alone. While dual-site culture practices may be useful, clinicians should balance the gain in sensitivity of bacteraemia detection against additive contamination risk.

Sustainable neonatal CLABSI surveillance: consensus towards new criteria in the Netherlands

BACKGROUND

Central line-associated bloodstream infections (CLABSI) are a main focus of infection prevention and control initiatives in neonatal care. Standardised surveillance of neonatal CLABSI enables intra- and interfacility comparisons which can contribute to quality improvement. To date, there is no national registration system for CLABSI in neonatal care in the Netherlands and several criteria are used for local monitoring of CLABSI incidence rates. To achieve standardised CLABSI surveillance we conducted a consensus procedure with regard to nationwide neonatal CLABSI surveillance criteria (SC).

METHODS

A modified Delphi consensus procedure for the development of nationwide neonatal CLABSI SC was performed between January 2016 and January 2017 in the Netherlands. An expert panel was formed by members of the Working Group on Neonatal Infectious Diseases of the Section of Neonatology of the Dutch Paediatric Society. The consensus procedure consisted of three expert panel rounds.

RESULTS

The expert panel achieved consensus on Dutch neonatal CLABSI SC. Neonatal CLABSI is defined as a bloodstream infection occurring more than 72 h after birth, associated with an indwelling central venous or arterial line and laboratory confirmed by one or more blood cultures. In addition, the blood culture finding should not be related to an infection at another site and one of the following criteria can be applied: 1. a bacterial or fungal pathogen is identified from one or more blood cultures; 2. the patient has clinical symptoms of sepsis and 2A) a common commensal is identified in two separate blood cultures or 2B) a common commensal is identified by one blood culture and C-reactive protein level is above 10 mg/L in the first 36 h following blood culture collection.

CONCLUSIONS

The newly developed Dutch neonatal CLABSI SC are concise, specified to the neonatal population and comply with a single blood culture policy in actual neonatal clinical practice. International agreement upon neonatal CLABSI SC is needed to identify best practices for infection prevention and control.

Analysis of Pathogen Distribution and Its Antimicrobial Resistance in Bloodstream Infections in Hospitalized Children in East China, 2015-2018

This study analyzed the pathogen distribution in bloodstream-infected (BSI) children hospitalized in Shandong Province from 2015 to 2018, to identify prevention strategies and select empiric antimicrobial therapy for BSI in children. Blood sample data from 14 107 children from 162 hospitals of Shandong Province were obtained from the China Antimicrobial Resistance Surveillance System and analyzed with WHONET 5.6 software. The results of the blood culture test showed the growth of 70.6% Gram-positive and 29.4% Gram-negative bacteria. Of the 14 107 blood isolates, 59.3% were collected from males and 40.7% were from females. Coagulase-negative staphylococci (47.1%) were the most commonly distributed pathogens. The distribution of pathogens varied according to age group and season. All Staphylococcus isolates were susceptible to vancomycin, teicoplanin and linezolid. Clinically, significant declines in penicillin-resistant Streptococcus pneumonia and carbapenem-resistant Escherichia coli were observed during the study period; however, detection rates of carbapenem-resistant Klebsiella pneumoniae increased over time (p < 0.05). Empiric antimicrobial therapy should be prescribed according to corresponding regional pediatric antimicrobial-resistant data.

Management of Neonates Born at ≤34 6/7 Weeks' Gestation With Suspected or Proven Early-Onset Bacterial Sepsis

Early-onset sepsis (EOS) remains a serious and often fatal illness among infants born preterm, particularly among newborn infants of the lowest gestational age. Currently, most preterm infants with very low birth weight are treated empirically with antibiotics for risk of EOS, often for prolonged periods, in the absence of a culture-confirmed infection. Retrospective studies have revealed that antibiotic exposures after birth are associated with multiple subsequent poor outcomes among preterm infants, making the risk/benefit balance of these antibiotic treatments uncertain. Gestational age is the strongest single predictor of EOS, and the majority of preterm births occur in the setting of other factors associated with risk of EOS, making it difficult to apply risk stratification strategies to preterm infants. Laboratory tests alone have a poor predictive value in preterm EOS. Delivery characteristics of extremely preterm infants present an opportunity to identify those with a lower risk of EOS and may inform decisions to initiate or extend antibiotic therapies. Our purpose for this clinical report is to provide a summary of the current epidemiology of preterm neonatal sepsis and provide guidance for the development of evidence-based approaches to sepsis risk assessment among preterm newborn infants.

Management of Neonates Born at ≥35 0/7 Weeks' Gestation With Suspected or Proven Early-Onset Bacterial Sepsis

The incidence of neonatal early-onset sepsis (EOS) has declined substantially over the last 2 decades, primarily because of the implementation of evidence-based intrapartum antimicrobial therapy. However, EOS remains a serious and potentially fatal illness. Laboratory tests alone are neither sensitive nor specific enough to guide EOS management decisions. Maternal and infant clinical characteristics can help identify newborn infants who are at risk and guide the administration of empirical antibiotic therapy. The incidence of EOS, the prevalence and implications of established risk factors, the predictive value of commonly used laboratory tests, and the uncertainties in the risk/benefit balance of antibiotic exposures all vary significantly with gestational age at birth. Our purpose in this clinical report is to provide a summary of the current epidemiology of neonatal sepsis among infants born at ≥35 0/7 weeks' gestation and a framework for the development of evidence-based approaches to sepsis risk assessment among these infants.

Dwell time and risk of central-line-associated bloodstream infection in neonates

BACKGROUND

Umbilical venous catheters (UVCs) or peripherally inserted central catheters (PICCs), widely used in high-risk neonates, may have a threshold dwell time for subsequent increased risk of central-line-associated bloodstream infection (CLABSI).

AIM

To evaluate the CLABSI risks in neonates having either UVC, PICC, or those having both sequentially.

METHODS

The study included 3985 infants who had UVC or PICC inserted between 2007 and 2009 cared for in 10 regional neonatal intensive care units: 1392 having UVC only (group 1), 1317 PICC only (group 2), and 1276 both UVC and PICC (group 3).

FINDINGS

There were 403 CLABSIs among 6000 venous catheters inserted, totalling 43,302 catheter-days. CLABSI rates were higher in group 3 infants who were of lowest gestation (16.9 per 1000 UVC-days and 12.5 per 1000 PICC-days; median: 28 weeks) when compared with group 1 (3.3 per 1000 UVC-days; 37 weeks) and group 2 (4.8 per 1000 PICC-days; 30 weeks). Life table and Kaplan-Meier hazard analysis showed that UVC CLABSI rate increased stepwise to 42 per 1000 UVC-days by day 10, with the highest rate in group 3 (85 per 1000 UVC-days). PICC CLABSI rates remained relatively stable at 12-20 per 1000 PICC-days. Compared to PICC, UVC had a higher adjusted CLABSI risk controlled for dwell time. Among group 3, replacing UVC electively before day 4 may have a trend of lower CLABSI risk than late replacement.

CONCLUSION

There was no cut-off duration beyond which PICC should be removed electively. Early UVC removal and replacement by PICC before day 4 might be considered.

Clinical and Microbiologic Characteristics of Early-onset Sepsis Among Very Low Birth Weight Infants: Opportunities for Antibiotic Stewardship

BACKGROUND

Most very low birth weight (VLBW, birth weight <1500 g) infants receive empiric antibiotics for risk of early-onset sepsis (EOS). The objective of this study was to determine the characteristics of VLBW infants with culture-confirmed EOS at a single center during 25 years and to identify opportunities for antibiotic stewardship.

METHODS

Retrospective cohort study includes VLBW infants admitted from 1990 to 2015. EOS was defined as isolation of a pathogen in blood or cerebrospinal fluid culture obtained at <72 hours of age. Clinical and microbiologic characteristics of EOS case infants were obtained by review of medical, laboratory and administrative records. Blood culture, antibiotic initiation and maternal discharge code data were available for all VLBW infants born between 1999 and 2013.

RESULT

One-hundred nine EOS cases (20.5/1000 VLBW births) occurred during the study period. Preterm labor, preterm rupture of membranes and/or the obstetrical diagnosis of chorioamnionitis were present in 106/109 cases (97%). Obligate anaerobic organisms accounted for 16% of cases. Time to culture positivity was 36 hours for 88% and 48 hours for 98% of cases. From 1999 to 2013, 97% of VLBW infants were evaluated for EOS and 90% administered empiric antibiotics; 22% of these infants were born by cesarean section to mothers with preeclampsia and without preterm labor or chorioamnionitis and had a 12-fold lower incidence of EOS compared with the remaining infants.

CONCLUSION

Decisions to initiate and discontinue empiric antibiotics among VLBW infants can be informed by the delivery characteristics of infected infants and by local microbiologic data.

Simultaneous Two-site Blood Culture for Diagnosis of Neonatal Sepsis

OBJECTIVE

To evaluate efficacy of two blood cultures taken simultaneously from two different sites as compared to standard practice of single blood culture in diagnosis of neonatal sepsis.

STUDY DESIGN

Prospective cohort study.

Setting

A tertiary-care center at a public hospital.

PARTICIPANTS

475 neonates admitted to intensive care unit with suspected sepsis, from August 2014-July 2015.

INTERVENTION

Two blood cultures drawn from two different peripheral veins in patients with suspected neonatal sepsis.

MAIN OUTCOME MEASURES

Increase in culture-positivity rate with use of two blood cultures.

RESULTS

475 babies with suspected sepsis were enrolled. 185 patients had only first culture positive (38.9%). When we added second culture positivity, yield increased to 221 (46.5%). Adding on second culture increased the culture yield by 36 (7.6%; 95% CI 2.41 to 12.79; P=0.018). The most common organisms isolated were E. coli, S. aureus and Candida spp. Major morbidities and mortality were more common in blood culture positive patients Contamination was ruled out in 25 babies who grew Coagulase negative Staphylococcus (CONS) (n=10) and Candida spp. (n=15) in either of the two cultures.

CONCLUSION

Two blood cultures taken simultaneously from two different sites improve rate of pathogen detection as compared to routine practice of single blood culture.

Understanding Bacterial Isolates in Blood Culture and Approaches Used to Define Bacteria as Contaminants: A Literature Review

BACKGROUND

Interpretation of blood culture isolates is challenging due to a lack of standard methodologies for identifying contaminants. This problem becomes more complex when the specimens are from sick young infants, as a wide range of bacteria can cause illness among this group.

METHODS

We used 43 key words to find articles published between 1970 and 2011 on blood culture isolates and possible contaminants in the PubMed database. Experts were also consulted to obtain other relevant articles. Selection of articles followed systematic methods considering opinions from more than 1 reviewer.

RESULTS

After reviewing the titles of 3869 articles extracted from the database, we found 307 relevant to our objective. Based on the abstracts, 42 articles were selected for the literature review. In addition, we included 7 more articles based on cross-references and expert advice. The most common methods for differentiating blood culture isolates were multiple blood cultures from the same subject, antibiograms and molecular testing. Streptococcus pneumoniae, Hemophilus influenzae, Neisseria meningitidis and group A and B streptococcus were always considered as pathogens, whereas Bacillus sp., Diphtheroids, Propionibacterium and Micrococcus were commonly regarded as contaminants. Coagulase-negative staphylococci were the most frequent isolates and usually reported as contaminants unless the patient had a specific condition, such as long-term hospitalization or use of invasive devices (catheters).

CONCLUSIONS

Inaccurate interpretation of blood culture may falsely guide treatment and also has long-term policy implications. The combination of clinical and microbiological knowledge, patient's clinical history and laboratory findings are essential for appropriate interpretation of blood culture.

Optimizing the Use of Antibacterial Agents in the Neonatal Period

Antibiotics are invaluable in the management of neonatal infections. However, overuse or misuse of antibiotics in neonates has been associated with adverse outcomes, including increased risk for future infection, necrotizing enterocolitis, and mortality. Strategies to optimize the use of antibiotics in the neonatal intensive care unit include practicing effective infection prevention, improving the diagnostic evaluation and empiric therapy for suspected infections, timely adjustment of therapy as additional information becomes available, and treating proven infections with an effective, narrow-spectrum agent for the minimum effective duration. Antibiotic stewardship programs provide support for these strategies but require the participation and input of neonatologists as stakeholders to be most effective.

Staphylococcal infections in infants: updates and current challenges

Staphylococci are common pathogens in the neonatal period. Increased survival of premature infants leads to prolonged hospital stay with associated risk factors for developing invasive staphylococcal disease. Challenges of diagnosing coagulase-negative staphylococcal infections result in conflicting definitions and inconsistent clinical practice. Resistance to methicillin influences the choice of empirical therapy.

Duration of vancomycin treatment for coagulase-negative Staphylococcus sepsis in very low birth weight infants

AIM

Vancomycin is widely used to treat late onset coagulase-negative Staphylococcus (CoNS) sepsis in very low birth weight (VLBW) infants. Although vancomycin is associated with a risk of toxicity and bacterial resistance, the appropriate duration of use has not been established. This study sought to investigate the association between the duration of vancomycin therapy and clinical outcome in VLBW infants with CoNS sepsis.

METHODS

The files of all VLBW infants treated for CoNS sepsis at a tertiary paediatric medical centre from 1995-2003 were reviewed for clinical data, laboratory variables and outcome. Only patients with two positive diagnostic blood cultures were included. The findings were analyzed by duration of vancomycin treatment after the last positive blood culture.

RESULTS

The study cohort included 126 infants, 48 treated for 5 days, 32 for 6-7 days, 31 for 8-10 days and 15 for >10 days. There were no differences among the groups in perinatal characteristics, central catheter dwell time, laboratory data including haematologic, renal and liver function tests, or rate of complications of prematurity. Five infants were diagnosed with infective endocarditis or aortic thrombi and were treated for >10 days. CoNS sepsis recurred in two infants (1.6%). No toxicity of vancomycin treatment was observed.

CONCLUSIONS

In VLBW infants with uncomplicated CoNS sepsis, treatment with vancomycin for 5 days after the last positive blood culture appears to be associated with a satisfactory outcome and no adverse effects. A well-controlled prospective multicentre study is needed to confirm these findings.

Comparative microbial analysis of paired amniotic fluid and cord blood from pregnancies complicated by preterm birth and early-onset neonatal sepsis

BACKGROUND

16S rRNA-based genomic analyses have revolutionized our understanding of infectious diseases. Many cases which were recognized as "idiopathic" are now known to have an infectious etiology. Here, we present a proof-of-concept study to examine the microbial link between intra-amniotic infection (IAI) and early-onset neonatal sepsis (EONS).

RESULTS

Using culture independent methods, we analyzed paired amniotic fluid (AF) and cord blood (CB) samples from 36 singleton pregnancies complicated by preterm birth (PTB), IAI, and/or EONS. PTB cases were grouped as 1) Group 1- neonatal blood culture-positive EONS (n=6). 2) Group 2- neonatal blood culture-negative presumed EONS with positive IAI (n=16). 3) Group 3- neonatal blood culture-negative presumed EONS with no IAI (n=7); 4) Group 4- no EONS or IAI (n=7). In addition, samples from term healthy deliveries (n=8) served as technical controls. A total of 31 species (15 non-redundant) were identified in AF, of which only 1/3 were cultivated. Significantly fewer microorganisms were detected in CB, with a total of 18 species (7 non-redundant) identified, of which only 2 (Escherichia coli, Streptococcus agalactiae) were cultivated. Of those, Bergeyella, Fusobacterium nucleatum, and Sneathia sanguinegens had not been detected in EONS before. The novel species identified in AF by PCR include Peptoniphilus harei and Lachnospiraceae sp. The majority (72%) of CB species were also detected in the matching AF, with E. coli and F. nucleatum as the most prevalent. The 16S rRNA sequences of paired AF and CB were 99.9-100% identical, while no identical sequences were found between different pregnancies.

CONCLUSIONS

Previously unrecognized, uncultivated or difficult-to-cultivate species are implicated in EONS. Microbial species in paired AF and CB likely share the same infectious origin. Given its prevalence in EONS, F. nucleatum should be placed on the same importance scale as E. coli.

Distinguishing true coagulase-negative Staphylococcus infections from contaminants in the neonatal intensive care unit

OBJECTIVE

To characterize true coagulase-negative Staphylococcus (CoNS) infections in infants receiving neonatal intensive care.

STUDY DESIGN

Retrospective cohort study of neonatal intensive care unit (NICU) infants with clinical sepsis and CoNS isolated from ≥ 2 blood cultures (BCs) or one BC and a sterile site (proved infection) or CoNS isolated from one BC and deemed significant after blinded data review (probable infection).

RESULT

In all, 98% of 40 proved and 96% of 55 probable infections occurred in infants with birth weight (BW) <2000 g and gestation <34 weeks. Total central lines (CLs) placed, but not CL duration or presence in situ, predicted proved (odds ratio (OR) 3.5, 95% confidence interval (CI) 1.4 to 8.3; P=0.005) and probable infection (OR 2.7, 95% CI 1.3 to 5.6; P=0.007) by multivariate analysis as did lethargy and gastric residuals.

CONCLUSION

True CoNS infection is unlikely in infants with BW >2000 g and gestation >34 weeks. Total CL required for care, lethargy and gastric residuals predicted true CoNS infection.

Persistent coagulase-negative staphylococci bacteremia in very-low-birth-weight infants

This study sought to expand current knowledge on the clinical and epidemiological characteristics of persistent coagulase-negative Staphylococcus (CoNS) bacteremia in very-low-birth-weight (VLBW) infants. Background and disease-related data were collected prospectively on 143 VLBW infants diagnosed with CoNS bacteremia at a pediatric tertiary medical center in 1995-2003. Findings were compared between those with persistent (positive blood cultures for >72 h under appropriate treatment ) and nonpersistent disease. Fifty-eight infants (40.6%) were found to have persistent bacteremia. There were no between-group differences in maternal characteristics, mode of delivery, newborn characteristics, dwell time of central venous and umbilical catheters, complications of prematurity, or mean hospital stay. The persistent bacteremia group had significantly higher rates of hypothermia at presentation (37.9% vs. 17.6%, p < 0.04), creatinine >1.2 mg% on treatment day 7 (13.7% vs. 2.4%, p < 0.02; transient phenomenon), and endocarditis (p < 0.03); one infant had an aortic thrombus. Predominantly breast-fed infants had a higher rate of negative cultures within 72 h of appropriate treatment than predominantly formula-fed infants (60% vs. 19%, p < 0.02). In conclusion, persistence of CoNS bacteremia is common in VLBW infants. Endocarditis should be excluded in all infants with persistent disease. Breast-feeding is associated with a shorter disease duration.

Strategies to prevent bacterial and fungal infection in the neonatal intensive care unit

Hospital-acquired infections are one of the leading causes of preventable morbidity and mortality in neonatal intensive care units (NICUs). Device-related infections, such as catheter-associated blood stream infections (CABSIs) and ventilator-associated pneumonia (VAP), are the most common nosocomial infections. This review examines the pathogenesis of CABSIs and methods, widely accepted and novel, that can be used to help prevent them. Strategies to prevent fungal infections, which are often associated with the presence of a central venous catheter, are also reviewed. Finally, the dilemmas in the diagnosis and prevention of VAP in the NICU are discussed.

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

OBJECTIVE

To evaluate the usefulness of two-site blood cultures for the documentation of bacterial clearance during initial treatment of culture proven neonatal sepsis.

DESIGN/METHODS

Clinical data were prospectively collected for 216 neonates who had blood cultures drawn for evaluation of possible sepsis. A positive diagnostic blood culture was followed by repeat blood cultures from two different peripheral sites after initiation of antimicrobial therapy.

RESULTS

Follow-up two-site cultures were drawn on 25 occasions at a median interval of 3 days after start of antimicrobial therapy for culture-proven sepsis in 15 neonates. On 12 occasions, follow-up blood cultures were both negative. On eight occasions, follow-up blood cultures grew the same organisms from both sites. However, follow-up two-site cultures on five occasions in four of the 15 infants grew organisms from one site but not the second site.

CONCLUSIONS

Two-site blood cultures seem necessary to document bacterial clearance in response to antimicrobial therapy for culture-proven sepsis, and may help determine the appropriate duration of antimicrobial therapy by reducing false-negative results.

Coagulase-negative staphylococcal infections in the neonate and child: an update

Coagulase-negative staphylococcus (CONS) infection is the most common bloodstream infection treated in neonatal and pediatric intensive care units and significantly impacts patient mortality and morbidity. Staphylococcus epidermidis is the most common CONS species isolated clinically and investigated for its pathogenicity and virulence. Difficulties exist in the differentiation of CONS infection from culture contamination in clinical specimens, as CONS is a common skin commensal. Most CONS isolates have the mecA gene and exhibit beta-lactam resistance. The glycopeptide antibiotics, such as vancomycin, are the mainstay in therapy, although resistance has been reported. Arbekacin, linezolid, and streptogramins are newer antibiotics being evaluated as alternatives to glycopeptides. Monoclonal and polyclonal antibodies have been developed against the cell-wall components of staphylococcus and may hold promise for immune prophylaxis and treatment of CONS infection.

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

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 early-onset 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 beta-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>or=1 ml.

Cloxacillin versus vancomycin for presumed late-onset sepsis in the Neonatal Intensive Care Unit and the impact upon outcome of coagulase negative staphylococcal bacteremia: a retrospective cohort study

Background

Coagulase negative staphylococcus (CONS) is the main cause of late-onset sepsis in Neonatal Intensive Care Units (NICU). Although CONS rarely causes fulminant sepsis, vancomycin is frequently used as empiric therapy. Indiscriminate use of vancomycin has been linked to the emergence of vancomycin resistant organisms. The objective of this study was to compare duration of CONS sepsis and mortality before and after implementation of a policy of selective vancomycin use and compare use of vancomycin between the 2 time periods.

Methods

A retrospective study was conducted of infants ≥4 days old, experiencing signs of sepsis with a first positive blood culture for CONS, during two 12-month periods. Late-onset sepsis was treated empirically with vancomycin and gentamicin during period 1, and cloxacillin and gentamicin during period 2. The confidence interval method was used to assess non-inferiority of the outcomes between the two study groups.

Results

There were 45 episodes of CONS sepsis during period 1 and 37 during period 2. Duration of sepsis was similar between periods (hazard ratio of 1.00, 95%CI: 0.64, 1.57). One death during period 2 was possibly related to CONS sepsis versus none in period 1. Vancomycin was used in 97.8% of episodes in period 1 versus 81.1% of episodes in period 2.

Conclusion

Although we failed to show non-inferiority of duration of sepsis in the cloxacillin and gentamicin group compared to the vancomycin and gentamicin group, duration of sepsis was clinically similar. Restricting vancomycin for confirmed cases of CONS sepsis resistant to oxacillin appears effective and safe, and significantly reduces vancomycin use in the NICU.

Variations in rates of nosocomial infection among Canadian neonatal intensive care units may be practice-related

Background

Nosocomial infection (NI), particularly with positive blood or cerebrospinal fluid bacterial cultures, is a major cause of morbidity in neonatal intensive care units (NICUs). Rates of NI appear to vary substantially between NICUs. The aim of this study was to determine risk factors for NI, as well as the risk-adjusted variations in NI rates among Canadian NICUs.

Methods

From January 1996 to October 1997, data on demographics, intervention, illness severity and NI rates were submitted from 17 Canadian NICUs. Infants admitted at <4 days of age were included. NI was defined as a positive blood or cerebrospinal fluid culture after > 48 hrs in hospital.

Results

765 (23.5%) of 3253 infants <1500 g and 328 (2.5%) of 13228 infants ≥1500 g developed at least one episode of NI. Over 95% of episodes were due to nosocomial bacteremia. Major morbidity was more common amongst those with NI versus those without. Mortality was more strongly associated with NI versus those without for infants ≥1500 g, but not for infants <1500 g. Multiple logistic regression analysis showed that for infants <1500 g, risk factors for NI included gestation <29 weeks, outborn status, increased acuity on day 1, mechanical ventilation and parenteral nutrition. When NICUs were compared for babies <1500 g, the odds ratios for NI ranged from 0.2 (95% confidence interval [CI] 0.1 to 0.4) to 8.6 (95% CI 4.1 to 18.2) when compared to a reference site. This trend persisted after adjustment for risk factors, and was also found in larger babies.

Conclusion

Rates of nosocomial infection in Canadian NICUs vary considerably, even after adjustment for known risk factors. The implication is that this variation is due to differences in clinical practices and therefore may be amenable to interventions that alter practice.

Features of invasive staphylococcal disease in neonates

OBJECTIVE

Most clinical descriptions of invasive staphylococcal disease (ISD) in neonates date from before the mid-1980s, when neonatal viability and intensive care differed substantially from current standards. We aimed to describe the contemporary incidence, clinical features, and outcome of infants with ISD in a neonatal intensive care unit.

METHODS

A retrospective cohort study was conducted of infants who had ISD and were in the neonatal intensive care unit of the Woman's Hospital of Texas, Houston, from January 2000 to June 2002. Confirmed ISD was defined as clinical sepsis and Staphylococcus aureus (SA) isolated from > or =1 blood culture (BC) or a sterile body site excluding urine or coagulase-negative staphylococci (CoNS) isolated from > or =2 BC or from 1 BC and a sterile body site. Probable ISD was defined as CoNS isolated from 1 BC or a sterile body site for which clinical and laboratory data review by 3 infectious disease specialists indicated that antimicrobial treatment was appropriate. Confirmed and combined confirmed plus probable cases were analyzed.

RESULTS

A total of 149 episodes (83 confirmed [39 SA, 44 CoNS], 66 probable) in 137 infants (mean gestational age [GA]: 27.6 weeks [22.4-36.4]; mean birth weight: 981 g [350-2995]) were reviewed. Four (3%) infants had early-onset infection (2 SA, 2 CoNS). Median age at infection onset was similar (17 days SA; 18 days CoNS). Intravascular catheters (IVC) were in situ in a minority of infants with ISD episodes (38% SA, 43% CoNS). CoNS more than SA infections were associated with very low birth weight (<1500 g), lower GA, a history of more IVCs and concurrent total parenteral nutrition, but IVC and parenteral nutrition days were similar. By multivariate analysis correcting for birth weight and complications of prematurity, hypoxia at the time of sepsis evaluation was significantly associated with CoNS and hypotension with SA infections; other clinical features were similar. Methicillin-resistant SA caused 8% of SA infections. Among bacteremic infants, SA more frequently than CoNS involved > or =2 sites. Overall, SA had more focal complications (primarily bone and joint) than CoNS, resulting in a 2- to 3-fold higher SA-associated morbidity rate. Mortality directly attributable to either organism was similar (5% SA; 5% confirmed, 3% confirmed/probable CoNS).

CONCLUSION

CoNS ISD occurred in smaller, more premature infants than SA and was IVC associated in a minority of cases. Hypoxia and hypotension were the only presenting features that differentiated CoNS and SA. SA-associated morbidity was substantial, but SA infection carried no greater risk of death (5%) than CoNS.

Clinical microbiology of bacterial and fungal sepsis in very-low-birth-weight infants

Twenty percent of very-low-birth-weight (<1500 g) preterm infants experience a serious systemic infection, and despite advances in neonatal intensive care and antimicrobials, mortality is as much as threefold higher for these infants who develop sepsis than their counterparts without sepsis during their hospitalization. Outcomes may be improved by preventative strategies, earlier and accurate diagnosis, and adjunct therapies to combat infection and protect the vulnerable preterm infant during an infection. Earlier diagnosis on the basis of factors such as abnormal heart rate characteristics may offer the ability to initiate treatment prior to the onset of clinical symptoms. Molecular and adjunctive diagnostics may also aid in diagnosing invasive infection when clinical symptoms indicate infection but no organisms are isolated in culture. Due to the high morbidity and mortality, preventative and adjunctive therapies are needed. Prophylaxis has been effective in preventing early-onset group B streptococcal sepsis and late-onset Candida sepsis. Future research in prophylaxis using active and passive immunization strategies offers prevention without the risk of resistance to antimicrobials. Identification of the differences in neonatal intensive care units with low and high infection rates and implementation of infection control measures remain paramount in each neonatal intensive care unit caring for preterm infants.

Controlling healthcare-associated infections: the role of infection control and antimicrobial use practices

Healthcare-associated infections are a major cause of morbidity and mortality in pediatric patients in the United States and throughout the world. Overall rates of infection range widely depending on the pediatric population, with the highest rates being in patients in neonatal intensive care units, followed by those in pediatric intensive care units, immunocompromised patients, and those undergoing surgical procedures. Risk factors for healthcare-associated infection include intrinsic and extrinsic factors. The major intrinsic factors are age, birth weight, underlying diseases, and immune status. The major extrinsic factors are presence of invasive devices and procedures. The major risk factors for healthcare-associated infection caused by antimicrobial-resistant pathogens are either the transmission of pathogens from person to person (directly or indirectly, usually via the hands of healthcare workers) or the emergence of resistance after exposure to antimicrobials. Preventing healthcare-associated infections caused by antimicrobial-resistant pathogens requires a comprehensive approach that includes: 1) preventing infections through the use of vaccines and prophylaxis; 2) minimizing the use of invasive devices; 3) understanding and fully implementing (and complying with) current guideline recommendations for the prevention of infections; and 4) using antimicrobials judiciously. Implementing such a comprehensive program will reduce healthcare-associated infections, reduce the prevalence of antimicrobial-resistant pathogens, improve patient outcomes, and reduce health care costs.

Platelet count and sepsis in very low birth weight neonates: is there an organism-specific response?

OBJECTIVE

Thrombocytopenia is commonly observed in very low birth weight (VLBW) neonates with sepsis. Specific platelet responses to different infectious agents have not been extensively characterized. The objectives of this study were to examine platelet counts and platelet indices in preterm neonates with culture-proven sepsis to determine if there are organism-specific platelet responses.

STUDY DESIGN

We analyzed a cohort of all VLBW neonates (birthweight <1500 g) born over a 4-year period and admitted to a single level III neonatal intensive care unit (N = 943). Thrombocytopenia was defined as a platelet count <100,000/mm(3). Platelet count, nadir, duration of thrombocytopenia, and mean platelet volume (MPV) were examined during episodes of culture-proven sepsis. Analysis of variance, Kruskal-Wallis, Mann-Whitney U, and chi(2) tests were used to compare groups, and data are expressed as mean +/- standard deviation.

RESULTS

Sepsis was diagnosed in 154 (16%) of 943 patients in the study population. Of the sepsis episodes, 54% were associated with thrombocytopenia and 61% with an elevation in MPV. Infections were grouped by organism type: Gram-positive bacteria (117/154, 76%), Gram-negative bacteria (24/154, 16%), and fungi (13/154, 8%). When compared with patients with Gram-positive sepsis, those with Gram-negative or fungal sepsis had a significantly lower initial platelet count, a lower platelet nadir, a higher incidence of thrombocytopenia, and a greater duration of thrombocytopenia. The decrease in platelet count from baseline was also significantly less in the Gram-positive infections than in the fungal infections. Although there was an overall increase in MPV from baseline, there were no differences between groups.

CONCLUSIONS

In our population of VLBW infants, sepsis is frequently associated with thrombocytopenia and an elevation in MPV. However, fungal and Gram-negative pathogens are associated with a lower platelet count and more prolonged thrombocytopenia compared with Gram-positive pathogens. We conclude that common pathogens causing sepsis have different effects on platelet kinetics.