Bactericidal activity against coagulase-negative staphylococci is impaired in infants receiving long-term parenteral nutrition

Persistent Coagulase-Negative Staphylococcal Bacteremia in Neonates: Clinical, Microbiological Characteristics and Changes within a Decade

Atypical outbreaks of persistent coagulase-negative staphylococci (CoNS) bacteremias, defined as three or more consecutive positive blood cultures with the same CoNS species, at least 48 h apart, have been reported in neonatal intensive-care units (NICUs). Our aim was to describe the profile of these cases in our NICU over a two-year period with the objective of assessing possible changes within a decade. Demographics, clinical and microbiological data were recorded for all CoNS bacteremias in our tertiary NICU during 2016–2017 and compared with the results of the same study in 2006–2007. Fifty-six cases of CoNS sepsis were recorded. Fourteen (25%) of them were persistent. There were no significant differences in demographic and clinical characteristics between cases with persistent vs. non-persistent bacteremia. Staphylococcus epidermidis was the most common species. In logistic regression analysis, biofilm production (β = 2.464, p = 0.04) was the most significant determinant for the development of persistent CoNS bacteremia. Our isolates were less likely to produce biofilm and carry ica operon as compared to those of 2006–2007. The cases of persistent CoNS sepsis have decreased within a decade, which could be attributed to the implementation of intensive infection control practices. Biofilm production remains the most important risk factor.

Epidemiology of Neonatal Septicemia in the Era of Extended Spectrum Beta-Lactamase Producing Bacteria: A Prospective Study in a Tertiary Referral Hospital

A surge of extended spectrum beta lactamase (ESBL)-producers is being witnessed in the neonatal intensive care units (NICUs). Hence, the present study was conducted to analyze both the bacteriological profile and clinical outcome of neonatal septicemia, and to identify the prevalence and sensitivity of the incriminated pathogens with emphasis on ESBL producers. We conducted this study in the NICU of a tertiary referral hospital over a one-year-period. All neonates with a clinical diagnosis of sepsis (371 participants) were enrolled. Blood cultures were performed, and subsequent cultures of various specimens were done according to clinical suspicion. Antibiotic susceptibility tests were carried out and the neonates were followed up until discharge. Out of the 371 neonates, 137 (37%) had positive blood culture results, of whom 49% died versus only 7.7% of neonates with a negative blood culture (P-value< 0.0001). Low birth weight, prematurity, and the duration of hospital stay were considered as positive blood culture risk factors. Meanwhile, among 85 cultures that yielded Gram-negative pathogens, 16 isolates were identified as ESBL producers with Klebsiella pneumoniae being the most frequently encountered isolate (19.7%). Of the neonates inflicted with ESBL-sepsis, 62.5% died versus 11.6% with non-ESBL sepsis. Judicious antibiotic stewardship together with infection control practices can hinder the spread of drug-resistant pathogens. This is especially compelling among the vulnerable population of the NICUs. Meanwhile, rapid diagnostic modalities and timely antibiotic susceptibility tests are of paramount importance to initiate appropriate therapy which can hugely impact the clinical prognosis.

Epidemiology and healthcare factors associated with neonatal enterococcal infections

OBJECTIVE

To investigate the epidemiology and healthcare factors associated with late-onset neonatal enterococcal infections.

DESIGN

Multicentre, multinational retrospective cohort study using prospectively collected infection data from a neonatal infection surveillance network between 2004 and 2016; this was supplemented with healthcare data from a questionnaire distributed to participating neonatal units.

SETTING

Sixty neonatal units across Europe (UK, Greece, Estonia) and Australia.

PATIENTS

Infants admitted to participating neonatal units who had a positive culture of blood, cerebrospinal fluid or urine after 48 hours of life.

RESULTS

In total, 414 episodes of invasive Enterococcus spp infection were reported in 388 infants (10.1% of a total 4083 episodes in 3602 infants). Enterococcus spp were the second most common cause of late-onset infection after coagulase-negative Staphylococcus spp and were strongly associated with necrotising enterocolitis (NEC) (adjusted OR 1.44, 95% CI 1.02 to 2.03, p=0.038), total parenteral nutrition (TPN) (adjusted OR 1.34, 95% CI 1.06 to 1.70, p=0.016), increasing postnatal age (per 1-week increase: adjusted OR 1.04, 95% CI 1.02 to 1.06, p<0.001) and decreasing birth weight (per 1 kg increase: adjusted OR 0.85, 95% CI 0.74 to 0.97, p=0.017). There was no evidence that inadequate nurse to patient staffing ratios in high-dependency units were associated with a higher risk of enterococcal infections.

CONCLUSIONS

Enterococcus spp were the second most frequent cause of late-onset infections. The association between enterococcal infections, NEC and TPN may inform empiric antimicrobial regimens in these contexts and provide insights into reducing these infections.

Late Onset Sepsis in Very Low Birth Weight Infants in the South American NEOCOSUR Network

BACKGROUND

The main aim is to determine the incidence and associated factors of late onset sepsis (LOS) in very low birth weight infants (500-1500 g), from the NEOCOSUR Network during years 2001-2013. Secondary objectives are to describe the microbiology of the first and second episode of LOS and to study the association between catheter dwell time and LOS.

METHODS

Demographic information and outcome data are prospectively and routinely collected across the network using predefined diagnostic criteria and online data entry. LOS was confirmed by isolation of the organism in blood or through cerebrospinal fluid in cultures. The participating countries were Argentina, Brazil, Chile, Paraguay, Peru and Uruguay.

RESULTS

Overall incidence was 22.2% (3066/13,821). Infants who developed LOS were smaller by weight and gestational age; also, they feature less prenatal care and prenatal steroids, and longer hospital stays. A greater number of infants in the LOS group had 1 minute Apgar Scores ≤3. Multivariate logistic regression analysis showed a positive association between LOS and necrotizing enterocolitis, mechanical ventilation requirements, patent ductus arteriosus, oxygen dependency at 36 weeks and death. The majority of first LOS episode was caused by coagulase-negative staphylococci (44.3%). An increased risk of LOS was observed in relation to catheter dwell time (6% per day of stay of central lines).

CONCLUSIONS

The incidence of LOS was associated with mechanical ventilation, patent ductus arteriosus, necrotizing enterocolitis and death. LOS was an important cause of morbidity and mortality in very low birth weight infants in our network, and coagulase-negative staphylococci was the most frequent causative microorganism.

Safety and efficacy of an olive oil-based triple-chamber bag for parenteral nutrition: a prospective, randomized, multi-center clinical trial in China

Background

Small studies suggest differences in efficacy and safety exist between olive oil-based (OLIVE) and soybean oil-based (SOYBEAN) parenteral nutrition regimens in hospitalized adult patients. This large, prospective, randomized (1:1), open-label, multi-center, noninferiority study compared the delivery, efficacy, and safety of OLIVE (N = 226) with SOYBEAN (N = 232) in Chinese adults (≥18 years) admitted to a surgical service for whom parenteral nutrition was required.

Methods

Treatments were administered for a minimum of 5 days up to 14 days (to achieve approximately 25 kcal/kg/day, 0.9 g/kg/day amino acids, 0.8 g/kg/day lipid). Impact of treatment on anabolic/catabolic and serum inflammatory, chemistry, and hematological markers, safety, and ease of use were assessed. The primary efficacy variable was serum prealbumin level at Day 5.

Results

OLIVE (n = 219) was not inferior to SOYBEAN (n = 224) based on the prealbumin least square geometric mean [LSGM] ratio [95 % CI] 1.12 [1.06, 1.19]; P = 0.002), improved the anabolic/catabolic status of patients enrolled in the study, and was well tolerated compared with SOYBEAN. Improved anabolic status was supported by significantly higher levels of prealbumin at Day 5, albumin at Day 5 and IGF-1 at Day 14 in the OLIVE group, while catabolism was similar between groups. C-reactive protein, intercellular adhesion molecule-1, procalcitonin, and oxidation were similar in each group, but infections were significantly lower with OLIVE (3.6 % versus 10.4 %; P < 0.01).

Conclusions

OLIVE provided effective nutrition, was well tolerated, was associated with fewer infections, and conferred greater ease-of-use than SOYBEAN.

Trial registration

NTC 01579097.

Intravenous lipids for preterm infants: a review

Extremely low birth weight infants (ELBW) are born at a time when the fetus is undergoing rapid intrauterine brain and body growth. Continuation of this growth in the first several weeks postnatally during the time these infants are on ventilator support and receiving critical care is often a challenge. These infants are usually highly stressed and at risk for catabolism. Parenteral nutrition is needed in these infants because most cannot meet the majority of their nutritional needs using the enteral route. Despite adoption of a more aggressive approach with amino acid infusions, there still appears to be a reluctance to use early intravenous lipids. This is based on several dogmas that suggest that lipid infusions may be associated with the development or exacerbation of lung disease, displace bilirubin from albumin, exacerbate sepsis, and cause CNS injury and thrombocytopena. Several recent reviews have focused on intravenous nutrition for premature neonate, but very little exists that provides a comprehensive review of intravenous lipid for very low birth and other critically ill neonates. Here, we would like to provide a brief basic overview, of lipid biochemistry and metabolism of lipids, especially as they pertain to the preterm infant, discuss the origin of some of the current clinical practices, and provide a review of the literature, that can be used as a basis for revising clinical care, and provide some clarity in this controversial area, where clinical care is often based more on tradition and dogma than science.

Intestinal Transplantation from Living Donors

Intestinal transplantation (ITx) represents the physiologic alternative to total parenteral nutrition (TPN) for patients suffering from life-threatening complications of irreversible intestinal failure. The number of transplants performed worldwide has been increasing for several years until recently. ITx has recently become a valid therapeutic option with a graft survival rate between 80 % and 90 % at 1 year, in experienced centers. These results have been achieved due to a combination of several factors: better understanding of the pathophysiology of intestinal graft, improved immunosuppression techniques, more efficient strategies for the monitoring of the bowel graft, as well as control of infectious complications and posttransplant lymphoproliferative disease (PTLD). In fact, this procedure is associated with a relatively high rate of complications, such as infections, acute rejection, graft versus host disease (GVHD), and PTLD, if compared to the transplantation of other organs. These complications may be, at least in part, the consequence of the peculiarity of this graft, which contains gut-associated lymphoid tissue and potentially pathogenic enteric flora. Furthermore, in these patients, the existing disease and the relative malnutrition could predispose them to infectious complications. Additionally, other factors associated with the procedure, such as laparotomy, preservation injury, abnormal motility, and lymphatic disruption, could all be implicated in the development of complications.

Neonatal host defense against Staphylococcal infections

Preterm infants are especially susceptible to late-onset sepsis that is often due to Gram-positive bacterial infections resulting in substantial morbidity and mortality. Herein, we will describe neonatal innate immunity to Staphylococcus spp. comparing differences between preterm and full-term newborns with adults. Newborn innate immunity is distinct demonstrating diminished skin integrity, impaired Th1-polarizing responses, low complement levels, and diminished expression of plasma antimicrobial proteins and peptides, especially in preterm newborns. Characterization of distinct aspects of the neonatal immune response is defining novel approaches to enhance host defense to prevent and/or treat staphylococcal infection in this vulnerable population.

Metabolomics reveals increased isoleukotoxin diol (12,13-DHOME) in human plasma after acute Intralipid infusion

Intralipid is a fat emulsion that is regularly infused into humans and animals. Despite its routine use, Intralipid infusion can cause serious adverse reactions, including immunosuppression. Intralipid is a complex mix of proteins, lipids, and other small molecules, and the effect of its infusion on the human plasma metabolome is unknown. We hypothesized that untargeted metabolomics of human plasma after an Intralipid infusion would reveal novel insights into its effects. We infused Intralipid and saline into 10 healthy men in a double-blind, placebo-controlled experiment and used GC/MS, LC/MS, and NMR to profile the small-molecule composition of their plasma before and after infusion. Multivariate statistical analysis of the 40 resulting plasma samples revealed that after Intralipid infusion, a less-well-characterized pathway of linoleic acid metabolism had resulted in the appearance of (9Z)-12,13-dihydroxyoctadec-9-enoic acid (12,13-DHOME, P < 10(-3)), a leukotoxin that has powerful physiological effects and is known to inhibit the neutrophil respiratory burst. Intralipid infusion caused increased plasma 12,13-DHOME. Given that 12,13-DHOME is known to directly affect neutrophil function, we conclude that untargeted metabolomics may have revealed a hitherto-unknown mechanism of intralipid-induced immunosuppression.

Dose of intravenous lipids and rate of bacterial clearance in preterm infants with blood stream infections

BACKGROUND

Intravenous lipid emulsion (IVLE) is an integral part of the total parenteral nutrition (TPN) regimen in neonates. The use of IVLE during sepsis is the subject of controversy because it may interfere with phagocytosis of microbes by macrophages and may lead to significant hypertriglyceridemia.

OBJECTIVE

This paper aims to study the rate of clearance of bacteria in relation to dose of IVLE administered to preterm infants with blood stream infections (BSIs).

METHODS

Preterm infants (mean gestational age ± SD, 32.0 ± 2.5 weeks) with culture-proven BSI and receiving TPN were randomized to two groups. The first group (n = 22) was given the usual dose of IVLE according to a standard protocol (starting from 0.5 g kg(-1) day(-1) and gradually increased by 1 g kg(-1) day(-1) to a maximum of 3.5 g kg(-1) day(-1)); in the second group (n = 20), IVLE were restricted at a dose of 1 g kg(-1) day(-1). Samples for blood cultures were withdrawn every 24 h until a negative culture was obtained. CRP was measured daily until its normalization. Serum triglycerides were monitored daily.

RESULTS

The rate of bacterial clearance was significantly more rapid in the restricted-dose IVLE group compared to the standard-dose group [72 (48-120) versus 144 (72-168) h, p = 0.001]. Daily weight increment was significantly greater in the standard-dose IVLE group compared to the restricted-dose IVLE group [25 (6.9-31.9) versus 0.9 (-3.3-11.7) g, p = 0.0001]. The duration of antibiotic use was significantly reduced in the restricted-dose IVLE group compared with the standard-dose IVLE group (10.0 ± 4.5 vs 14.9 ± 5.1 days; p = 0.003). The durations of TPN, mechanical ventilation, and hospitalization were not significantly different between groups.

CONCLUSIONS

Restriction of the dose of IVLE to 1 g kg(-1) day(-1) in preterm infants with BSI is associated with earlier negative blood cultures and reduced duration of antibiotic therapy but was associated with a lower daily weight increments.

Dacryocystitis: Systematic Approach to Diagnosis and Therapy

The objective of this paper is to review the main findings of the largest studies on the etiopathogenesis and microbiology of the development of dacryocystitis and to formulate clinical and surgical guidelines based on said studies and on our experience at Cruces Hospital, the Basque Country, Spain. The most common sign of this entity is the distal nasolacrimal duct obstruction, and this should be treated to prevent clinical relapse. The time when surgery should be indicated mainly depends on the clinical signs and symptoms, age and general status of a patient. Given the germs isolated in cases of dacryocystitis, antibiotic therapy against Gram positive (S. aureus, S. pneumoniae, S. epidermidis) and Gram negative bacteria (H. influenzae, P. aeruginosa) should be administered, orally in adults and intravenously in pediatric patients, prior to surgery. Gentamicin and amoxicillin-clavulanic acid have been found to be effective against the bacteria commonly implicated in the etiopathogenesis of this entity.

Anti-tumor necrosis factor-α monoclonal antibody alleviates parenteral nutrition-associated liver disease in mice

BACKGROUND

The authors aimed to investigate the role of anti-tumor necrosis factor (TNF)-α monoclonal antibody treatment in a mouse model of parenteral nutrition-associated liver disease (PNALD).

METHODS

C57BL/6J male mice (aged 6-8 weeks) were randomly assigned to 3 groups: parenteral nutrition (PN), PN with anti-TNF-α monoclonal antibody treatment (PN + mAb), and controls. A central venous catheter was inserted for intravenous infusion of a PN solution (PN and PN + mAb groups) or saline (controls) for 7 days. Liver pathology, hepatic biochemical indicators, and serum TNF-α concentrations were analyzed. Levels of hepatic bsep, mdr1a/mdr1b, mdr2, and mrp2 mRNA were also evaluated in each group.

RESULTS

The PN group showed significant increases in serum transaminase, direct bilirubin, and bile acids relative to the control group (P < .05). Histopathological changes in this group were consistent with early stage cholestasis. The pathological score and serum alanine aminotransferase, total bilirubin, and direct bilirubin levels were improved in the PN + mAb group relative to the PN group (P < .05). The PN group showed significantly lower hepatic bsep, mdr1a/mdr1b, mdr2, and mrp2 mRNA expression than the controls (P < .05), but these were significantly increased compared to the PN group (P < .05).

CONCLUSIONS

Infliximab administered at a single dose of 5 mg/kg body weight ameliorated the progression of PNALD and improved the expression of hepatic ABC transporter genes. Therefore, anti-TNF-α monoclonal antibody may be a beneficial therapy for patients with PNALD.

Total parenteral-nutrition-mediated dendritic-cell activation and infiltration into the small intestine in a rat model

PURPOSE

Total parenteral nutrition (TPN) is commonly carried out in the clinical setting. However, effects of TPN on the immune system, including dendritic cells (DC), are not well understood. The purpose of this study was to determine whether TPN affects DC activation and infiltration into the intestinal barrier.

METHODS

Male Wistar rats were given conventional nutrition (CN) or TPN for 7 days. DCs were visualized by immunohistochemistry. Levels of nucleotide-binding oligomerization domain protein 2 (NOD2) and high-mobility group box 1 (HMGB1) protein were assessed by Western blot.

RESULTS

The number of DCs at the small intestinal barrier was significantly increased in the TPN group (9.2 ± 3.1 cells/microscopic field) compared with the CN group (0.5 ± 0.6 cells/microscopic field; p < 0.05), as were protein expression levels of NOD2 and HMGB1.

CONCLUSION

These results suggest that TPN increases activation and infiltration of DCs into the small intestine, potentially involving an increase in NOD2 and HMGB1 levels in the small intestine.

State of the art review: Intravenous fat emulsions: Current applications, safety profile, and clinical implications

OBJECTIVE

To review the current state of the science regarding intravenous fat emulsions (IVFEs), with an emphasis on their safety profile.

DATA SOURCES

Articles were identified via a search of the MEDLINE database, including publications from 1979 to December 2009, using a search string that included the terms parenteral nutrition, lipid emulsion, fat emulsion, IVFE, safety, adverse effect, neonate intralipid, and terms describing a range of specific adverse events (AEs) such as pancreatitis.

STUDY SELECTION AND DATA EXTRACTION

We selected articles that allowed us to compare the results of clinical trials involving delivery of medications via IVFEs with the historical use and effects of IVFEs in parenteral nutrition, with an emphasis on AEs. We focused on 2 drugs in current use that are administered intravenously in lipid emulsions: propofol and clevidipine.

DATA SYNTHESIS

Clearance of the fat particles in IVFEs is mediated by the enzyme lipoprotein lipase. AEs are more likely if the rate or duration of IVFE administration exceeds the enzyme's clearance capacity. AEs are also more likely after administration of a 10% IVFE formulation than a 20% formulation, because the higher concentration of free phospholipid in the 10% formulation interferes with lipoprotein lipase activity. AEs can be reduced by administering IVFEs at a dosage < or = 2.5 g/kg/day and at a rate < or = 0.11 g/kg/h. The anesthetic agent propofol, which is formulated in a 10% IVFE, has been used clinically for 25 years. Typical AEs associated with propofol use include infection, high plasma triglyceride concentrations, and pancreatitis. Recent clinical trials involving clevidipine, which is formulated in a 20% IVFE, have demonstrated a low rate of lipid-related AEs.

CONCLUSIONS

The results of this review demonstrate that IVFEs are well tolerated when administered in accordance with guideline recommendations.

The timing of antibiotic administration in the management of infant dacryocystitis

PURPOSE

To report (1) the prevalence of bacteremia among infants with dacryocystitis and (2) the influence of timing of antibiotic administration on the need for repeat probing in the management of these patients.

METHODS

A retrospective analysis of the hospital records of 25 infants < or =6 weeks of age treated for acute dacryocystitis was conducted, including analysis of laboratory data and outcomes.

RESULTS

Of 22 infants who underwent blood cultures, 5 (22.7%) were bacteremic. Twenty-one of the 25 infants underwent nasolacrimal duct probing. Infants who received preoperative antibiotics were less likely to require a repeat probing than those who did not (6% vs. 80%), and this difference was statistically significant (p = 0.004).

CONCLUSIONS

The high rate of bacteremia in this series of patients and the significantly lower incidence of repeat probing among infants who received preprocedural antibiotics suggests that blood cultures and subsequent administration of intravenous antibiotics should be considered prior to probing of infants with dacryocystitis.

Neonatal immune responses to coagulase-negative staphylococci

PURPOSE OF REVIEW

Coagulase-negative staphylococci have emerged as the most common nosocomial pathogen in neonatal intensive care units worldwide. Our understanding of the interactions between coagulase-negative staphylococci and the immune system is incomplete, especially in the newborn. This review summarizes current knowledge on the human immune response to coagulase-negative staphylococci, with particular emphasis on the neonatal innate immune system.

RECENT FINDINGS

There are very limited data on innate immune responses to coagulase-negative staphylococci in neonates. Levels of serum proteins, including transplacental anti-coagulase-negative staphylococci immunoglobulin and complement, correlate with gestational age, and this relative deficiency in preterm infants contributes to their suboptimal opsonization and impaired bacterial killing of coagulase-negative staphylococci. In adults, coagulase-negative staphylococci elicit significant cytokine responses in vitro, which are probably partly mediated by Toll-like receptors, including Toll-like receptor type 2, but these pathways have not been characterized in the high-risk neonatal population.

SUMMARY

The susceptibility of human preterm neonates to coagulase-negative staphylococci relates partly to the immaturity of the neonatal immune response. Strategies to reduce the burden of coagulase-negative staphylococci infections require a thorough understanding of host-pathogen interactions, particularly the engagement of coagulase-negative staphylococci by the neonatal innate immune system.

High-dose oral erythromycin decreased the incidence of parenteral nutrition-associated cholestasis in preterm infants

BACKGROUND & AIMS

Feeding intolerance because of functional gastrointestinal dysmotility and parenteral nutrition-associated cholestasis (PNAC) are common problems in preterm, very-low-birth-weight (VLBW) infants. This double-blind, randomized, placebo-controlled study aimed to assess the effectiveness of "high-dose" oral erythromycin as a prokinetic agent in decreasing the incidence of PNAC. Two secondary end points, including the time to achieve full enteral feeding and the duration of parenteral nutrition, were also evaluated.

METHODS

Infants consecutively admitted to the neonatal unit were randomized to receive erythromycin (12.5 mg/kg/dose every 6 hours for 14 days) or an equivalent volume of normal saline (placebo) if they attained less than half the total daily fluid intake (<75 mL/kg/day) as milk feeds on day 14 of life.

RESULTS

Of 182 VLBW infants enrolled, 91 received erythromycin. The incidence of PNAC was significantly lower in erythromycin-treated infants (18/91) compared with placebo infants (37/91; P = .003). Treated infants achieved full enteral nutrition significantly earlier (mean, 10.1; SE, 1.7 days; P < .001), and the duration of parenteral nutrition was also significantly decreased by 10 days (P < .001). Importantly, fewer infants receiving erythromycin had 2 or more episodes of septicemia (n = 4) compared with placebo patients (n = 13, P = .03). No serious adverse effect was associated with erythromycin treatment.

CONCLUSIONS

High-dose oral erythromycin can be considered as a rescue measure for VLBW infants who fail to establish adequate enteral nutrition and in whom anatomically obstructive pathologies of the gastrointestinal tract have been excluded.

Risk factors for late-onset health care-associated bloodstream infections in patients in neonatal intensive care units

BACKGROUND

There are few data comparing risk factors for catheter-related (CR) versus non-CR bloodstream infection (BSI) or for BSI caused by gram-positive versus gram-negative organisms. The aims of this study were to compare risk factors for CR versus non-CR BSI and to compare risk factors for BSI associated with gram-negative versus gram-positive organisms among infants hospitalized in two neonatal intensive care units (NICUs).

METHODS

Data were collected prospectively over a 2-year period to assess risk factors among 2,935 neonates from two NICUs.

RESULTS

Among all neonates, in addition to low birth weight and presence of a central venous catheter, hospitalization in NICU 1 (relative risk [RR]: 1.60, 95% confidence intervals [CI]: 1.14, 2.24) was a significant predictor of BSI. In neonates with a central catheter total parenteral nutrition (TPN) was a significant risk factor for BSI (RR: 4.69, 95% CI: 2.22, 9.87). Ventilator use was a significant risk factor for CR versus non-CR BSI (RR: 3.74, 95% CI: 1.87, 7.48), and significantly more CR BSI were caused by gram-positive (77.1%) than by gram-negative organisms (61.4%), P = .03.

CONCLUSIONS

This study confirmed that central venous catheters and low birth weight were risk factors for neonates with late-onset healthcare-associated BSI and further elucidated the potential risks associated with TPN and ventilator use in subgroups of neonates with BSI. Additional studies are needed to examine the incremental risk of TPN among infants with central venous catheters and to understand the link between CR BSI and ventilator use. Preventive strategies for BSI in neonates in NICUs should continue to focus on limiting the use of invasive devices.

Early central catheter infections may contribute to hepatic fibrosis in children receiving long-term parenteral nutrition

BACKGROUND

Bacterial infections in infants constitute a risk factor for parenteral nutrition (PN)-related cholestasis. The possible role of infections in the development of liver fibrosis, the most severe long-term complication, has yet to be documented. This study retrospectively compares the incidence of sepsis in children with and without severe liver fibrosis.

PATIENTS AND METHODS

Medical reports of 30 children in prolonged PN programs between March 1985 and March 2000 were reviewed. Starting at birth, the mean PN duration was 65 months (range, 8-150 months). According to the results of liver biopsy (LB), patients were split into 2 groups: group A (n = 16) with severe liver fibrosis (ie, septal fibrosis involving >50% of portal fields or cirrhosis) and group B (n = 14) with normal hepatic architecture or mild fibrosis (<50% of portal fields).

RESULTS

Duration of PN at the time of LB was shorter in group A (30.5 months; range, 8-96 months) than in group B (105 months; range, 37-150 months; P < 0.001). In group A the incidence of sepsis was significantly higher than in group B (3.2 +/- 0.3/year vs 1.5 +/- 0.2/year) and the first infection occurred earlier (group A, 1 month [range, 1-2 months]; group B, 4 months [range, 1-19 months]). By contrast, both groups were similar in terms of pregnancy duration, birth weight, age of PN onset, underlying diseases, mode of PN delivery, and number of cholestasis episodes.

CONCLUSIONS

Incidence and early onset of infections may contribute to the development of liver fibrosis in cases of long-term PN. New strategies are required in prevention and treatment of infections in children receiving PN.

Induction and modulation of apoptosis in neonatal monocytes by polyunsaturated fatty acids

Polyunsaturated fatty acids (PUFAs), known modulators of the immune response, are the source of essential fatty acids in total parenteral nutrition-dependent patients. Critically ill infants on TPN have an increased incidence of sepsis, and lipid emulsions depress various immune functions. Recent studies have demonstrated that PUFAs induce apoptosis in various tissue cells in vitro and ex vivo. The susceptibility of neonatal monocytes, as major early effector cells in the host response to sepsis, to PUFA-mediated apoptosis and the mechanisms associated with PUFA-induced apoptosis were investigated. Both n-3 and n-6 PUFAs induced rapid, dose-dependent cell death in purified monocytes. Polyunsaturated fatty acids induced significant activation of upstream caspases 8 and 9 as well as caspase 3. The PUFA treatment resulted in a 4-fold increase in oxidative stress and a loss of monocyte mitochondrial potential compared with carrier controls (P < .05). The addition of cyclosporin, which blocks the development of mitochondrial transition pores, completely abolished the proapoptotic effects of PUFAs. Although Trolox (Sigma Aldrich) reduced PUFA-induced intracellular oxidative stress in neonatal monocytes, apoptosis was not blocked by this potent antioxidant. The data identify PUFAs as potent inducers of monocyte apoptosis, which can occur independently of the induction of oxidative stress, by using a mitochondrial dependent pathway. The TPN-dependent infant may be particularly sensitive to such PUFA effects, having a relatively poor capacity to both use and clear PUFAs.

Impaired energy metabolism during neonatal sepsis: the effects of glutamine

Neonatal sepsis is an important cause of morbidity and mortality as a result of multiple organ system failure, particularly in neonates requiring total parenteral nutrition. Suitable therapies and support are needed both to prevent sepsis and to prevent multiple organ failure. After bacterial infection, pro-inflammatory cytokines trigger the antimicrobial activity of macrophages and neutrophils, resulting in production of reactive species such as H2O2, NO, superoxide and peroxynitrite. However, excess production can lead to host tissue damage. Incubation of either hepatocytes or heart mitochondria from neonatal rats with these reactive species, or with cytokines, leads to impairment of mitochondrial oxidative function, and in an animal model of neonatal sepsis similar results to thein vitrofindings have been demonstrated. Recentin vivostudies, using indirect calorimetry of suckling rat pups, show that during endotoxaemia there is a profound hypometabolism, associated with hypothermia. Having determined that cellular oxidative function may be impaired during sepsis, it is of great importance to try to identify therapeutic measures. Much interest has been shown in glutamine, which may become essential during sepsis. It has been shown that hepatic glutamine is rapidly depleted during endotoxaemia. When hepatocytes from endotoxaemic rats were incubated with glutamine, there was a restoration of mitochondrial structure and metabolism.In vivo, intraperitoneal injection of glutamine into endotoxic suckling rats partially reversed hypometabolism, markedly reduced the incidence of hypothermia and improved clinical status. These results suggest that glutamine has a beneficial effect during sepsis in neonates.

Persistent bacteremia and severe thrombocytopenia caused by coagulase-negative Staphylococcus in a neonatal intensive care unit

OBJECTIVE

Coagulase-negative Staphylococcus (CoNS) is the most frequent cause of late-onset sepsis in NICUs, but mortality is rare and morbidity is unusual. We report a new syndrome of CoNS sepsis characterized by significant morbidity and persistent bacteremia despite aggressive antibiotic therapy and no identified focus of infection.

METHODS

We conducted a retrospective review of infants in the NICU with CoNS bacteremia between 2000 and 2002. Statistical analysis included an initial exploratory analysis followed by logistic regression. Microbiological identification of all isolates and molecular typing were performed.

RESULTS

Thirty-one neonates with persistent CoNS bacteremia were compared with 60 randomly selected neonates from a group of 140 with nonpersistent CoNS bacteremia. The clinical manifestations at presentation, gestational ages, and birth weights were similar in the 2 groups. Thrombocytopenia was present in 26 (84%) neonates with persistent CoNS bacteremia but only in 8 (13%) neonates in the nonpersistent group. Central venous catheterization increased the risk for persistent CoNS bacteremia, but 42% of the persistent group was never catheterized. Staphylococcus epidermidis was the most common isolate in both groups. Molecular typing failed to identify a predominant clone.

CONCLUSIONS

The syndrome of persistent CoNS septicemia is remarkable for thrombocytopenia and persistence in the absence of central venous catheterization. Clinical manifestations at presentation and demographic characteristics did not discriminate between the persistent and nonpersistent groups. We did not identify the emergence of a particularly virulent clone, but it is possible that some strains of CoNS have acquired the capacity to persist under different conditions.

The effects of long-term total parenteral nutrition on gut mucosal immunity in children with short bowel syndrome: a systematic review

BACKGROUND: Short bowel syndrome (SBS) is defined as the malabsorptive state that often follows massive resection of the small intestine. Most cases originate in the newborn period and result from congenital anomalies. It is associated with a high morbidity, is potentially lethal and often requires months, sometimes years, in the hospital and home on total parenteral nutrition (TPN). Long-term survival without parenteral nutrition depends upon establishing enteral nutrition and the process of intestinal adaptation through which the remaining small bowel gradually increases its absorptive capacity. The purpose of this article is to perform a descriptive systematic review of the published articles on the effects of TPN on the intestinal immune system investigating whether long-term TPN induces bacterial translocation, decreases secretory immunoglobulin A (S-IgA), impairs intestinal immunity, and changes mucosal architecture in children with SBS. METHODS: The databases of OVID, such as MEDLINE and CINAHL, Cochran Library, and Evidence-Based Medicine were searched for articles published from 1990 to 2001. Search terms were total parenteral nutrition, children, bacterial translocation, small bowel syndrome, short gut syndrome, intestinal immunity, gut permeability, sepsis, hyperglycemia, immunonutrition, glutamine, enteral tube feeding, and systematic reviews. The goal was to include all clinical studies conducted in children directly addressing the effects of TPN on gut immunity. RESULTS: A total of 13 studies were identified. These 13 studies included a total of 414 infants and children between the ages approximately 4 months to 17 years old, and 16 healthy adults as controls; and they varied in design and were conducted in several disciplines. The results were integrated into common themes. Five themes were identified: 1) sepsis, 2) impaired immune functions: In vitro studies, 3) mortality, 4) villous atrophy, 5) duration of dependency on TPN after bowel resection. CONCLUSION: Based on this exhaustive literature review, there is no direct evidence suggesting that TPN promotes bacterial overgrowth, impairs neutrophil functions, inhibits blood's bactericidal effect, causes villous atrophy, or causes to death in human model.The hypothesis relating negative effects of TPN on gut immunity remains attractive, but unproven. Enteral nutrition is cheaper, but no safer than TPN. Based on the current evidence, TPN seems to be safe and a life saving solution.

Melatonin protects from, but does not reverse, the effects of mediators of sepsis on liver bioenergetics

BACKGROUND

Reactive oxygen species (ROS) have been reported to play a significant role in the pathogenesis of sepsis and liver dysfunction. In particular, neonates are at risk for sepsis and have less protection against oxidation. Melatonin has been reported to reduce the oxidative stress status in neonates with sepsis. Little is known about the effect of melatonin on liver bioenergetics. The aim of this study was to investigate the protective effect of melatonin on hepatocyte oxidative energy metabolism against hydrogen peroxide (H2O2), a free radical mediator of septic damage.

METHODS

Hepatocytes were isolated from neonatal suckling rats (11-15 days old). The cells, respiring on palmitate, were exposed to H2O2 at the concentration of 2 mmol/l, melatonin alone at 1 micromol/l or 10 micromol/l, or H2O2 plus melatonin at each of the two concentrations. Oxygen consumption was measured polarographically. In subsequent experiments, melatonin was added after the hydrogen peroxide.

RESULTS

Hydrogen peroxide significantly reduced hepatocyte oxygen consumption ( p<0.001), but melatonin added at the same time was able to prevent this effect ( p<0.001). However, melatonin at a low dose significantly inhibited hepatocyte oxygen consumption ( p<0.001), an effect which has not been previously described. When melatonin was added to cells after they had been exposed to hydrogen peroxide, a beneficial effect was not observed, indicating that melatonin is not able to reverse the effects of hydrogen peroxide.

CONCLUSION

Melatonin has a protective effect on hepatocyte oxidative metabolism, improving mitochondrial function by counteracting oxidative stress.

Gut overgrowth with abnormal flora: the missing link in parenteral nutrition-related sepsis in surgical neonates

BACKGROUND AND AIMS

Patients receiving parenteral nutrition are at risk of septicaemia. Intestinal dysmotility and impaired gut immunity due to parenteral nutrition promote bacterial overgrowth. Gut overgrowth with aerobic Gram-negative bacilli (AGNB) impairs systemic immunity. The aim of this study was to determine the potential role of gut overgrowth with AGNB in the pathogenesis of septicaemia related to parenteral nutrition.

METHODS

A prospective 5 y study of surgical infants less than 6 months of age was undertaken. Surveillance samples of the oropharynx and gut were obtained at the start of parenteral nutrition and thereafter twice weekly, to detect AGNB carriage. Blood cultures were taken on clinical indication only.

RESULTS

Two-hundred and eight infants received parenteral nutrition for 6271 days (median 13 days, range 1-512 days). The incidence of AGNB carriage was 42%, whilst the septicaemia rate was 15%. Eighty-four percent of septicaemic infants carried AGNB, whilst 16% never carried AGNB (P<0.005). Carriage developed significantly earlier than septicaemia.

CONCLUSIONS

The incidence of septicaemia was significantly greater in the subset of abnormal carriers. Although gut overgrowth with abnormal flora reflects illness severity, the fact that it preceded septicaemia implicates AGNB overgrowth, per se, as a contributory factor in the development of septicaemia related to parenteral nutrition. Prevention is unlikely to be successful if it ignores the abnormal flora.

Surgical infants on total parenteral nutrition have impaired cytokine responses to microbial challenge

BACKGROUND/PURPOSE

Cytokines are essential for the prevention of microbial infections. Total parenteral nutrition (TPN) in infancy is associated with an increased risk of infection, and this could be related to altered cytokine production. The aim of the study was to determine if cytokine production is altered in monocytes from surgical infants receiving TPN.

METHODS

There were 3 study groups: (a) infants receiving TPN, (b) enterally fed healthy control infants, and (c) enterally fed healthy control adults. Blood samples were incubated with either Escherichia coli LPS, Staphylococcus epidermidis, or with medium alone. Flow cytometry was used to measure monocyte intracellular cytokine: tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, IL-1beta.

RESULTS

After LPS stimulation, the percent of monocytes producing TNF-alpha and IL-6 were lower in infants on TPN than both control infants and adults. This was most apparent for TNF-alpha. The difference for IL-1beta was significant only between infant on TPN and control adults. When blood was stimulated with S. epidermidis, all 3 cytokines were significantly lower in the TPN group compared with control adults. However, the differences between infants on TPN and infant controls only reached statistical significance for IL-6.

CONCLUSIONS

The inflammatory response to bacterial challenge is impaired in infants on TPN compared with enterally fed infants or adults. The pattern of this response may be dependent on the nature of the microbial challenge. Our results indicate that the susceptibility of TPN-fed surgical infants to bacterial infections may in part be caused by impaired cytokine responses after bacterial invasion.

Glutamine improves impaired cellular exudation and polymorphonuclear neutrophil phagocytosis induced by total parenteral nutrition after glycogen-induced murine peritonitis

Clinical and laboratory evidence shows that enteral feeding significantly reduces pneumonia and intra-abdominal abscess formation after celiotomy for severe trauma. Supplementation of total parenteral nutrition (TPN) with glutamine (GLN) supports impaired immunity induced by TPN in several animal and human studies. This work investigates the peritoneal cellular response and polymorphonuclear neutrophil (PMN) bactericidal function after mouse chemical peritonitis after TPN with and without GLN. Thirty-three mice received chow, TPN, or 2% GLN-supplemented TPN (GLN-TPN) for 5 days. All mice then received 2 mL of a 1% glycogen solution intraperitoneally to induce cell exudation, and peritoneal exudative cells (PECs) were recovered 4 h later. Total and differential PEC numbers, as well as PMN phagocytosis, reactive oxygen intermediate production (ROI), CD11b (integrin aM chain) expression, and CD16/32 (Fcgamma II/III receptor) expression were measured. PMN, macrophage, and lymphocyte cell numbers were significantly lower with TPN than with chow or GLN-TPN groups, with no differences between chow and GLN-TPN. TPN significantly lowered peritoneal PMN phagocytosis compared with chow (P < 0.05) and approached significance with GLN-TPN (P = 0.06). There were no significant differences in ROI production or CD11b and CD16/32 expression on peritoneal PMN. GLN supplementation improved the reduction in cell exudation and PMN phagocytosis induced by TPN after chemical peritonitis.

Infection rates in surgical neonates and infants receiving parenteral nutrition: a five-year prospective study

We performed a prospective, observational, cohort study on 208 surgical neonates and infants between 1992 and 1997. Surveillance cultures of the oropharynx and rectum were obtained at the start of parenteral nutrition and thereafter twice weekly. Blood cultures were taken on clinical indication only. Microbial translocation was diagnosed when the micro-organisms in the blood were not distinguishable from those carried in the oropharynx and/or rectum. Liver function was monitored weekly and when septicaemia was suspected. The incidence of septicaemia was 15%. The predominant micro-organisms (86%) were the low-level pathogens, coagulase-negative staphylococci and enterococci. Potential pathogens, including aerobic Gram-negative bacilli, were responsible for the remainder. Microbial translocation was responsible for 84% of septicaemic episodes in 76% of patients. The potential pathogens caused septicaemia significantly later than coagulase-negative staphylococci, at a time when liver function was significantly more impaired. In neonates and infants receiving parenteral nutrition, septicaemia is mainly a gut-derived phenomenon and requires novel strategies for prevention.

Feeding the intensive care patient

The present review highlights recent findings (focusing on papers published between October 1999 and December 2000) in nutritional support of intensive care unit patients. During the past year, research focused on the use of enteral nutrition versus parenteral nutrition, and on the best composition of enteral nutrition and parenteral nutrition according to the clinical condition of the patient. With regard to enteral nutrition, the pH of nutritional support, the timing of administration and the technique of tube placement were debated. Immunomodulating agents and hormonal manipulations may improve outcomes of critically ill patients, but still warrant further research before they can be recommended for routine clinical use.