Michaela Langgartner

Immaturity of Infection Control in Preterm and Term Newborns Is Associated with Impaired Toll-Like Receptor Signaling

The impaired infection control related to the functional immaturity of the neonatal immune system is an important cause of infection in preterm newborns. We previously reported that constitutive Toll-like receptor (TLR) 4 expression and cytokine secretion on lipopolysaccharide (LPS) stimulation increases with gestational age. Here, we analyzed constitutive monocyte TLR2 expression and evaluated the expression profiles of the proximal downstream adapter molecule myeloid differentiation factor 88 (MyD88). We further investigated activation of protein kinases p38 and extracellular regulated kinsase (ERK) 1/2 in CD14 monocytes after ex vivo stimulation with bacterial TLR ligands (LPS and lipoteichoic acid [LTA]). The functional outcome of the stimulation was determined by cytokine secretion. Monocytes from 31 preterm newborns (<30 weeks of gestation, n=16; 30-37 weeks of gestation, n=15), 10 term newborns, and 12 adults were investigated. In contrast to TLR4 expression, TLR2 levels did not differ between age groups. However, MyD88 levels were significantly lower in preterm newborns. Activation of p38 and ERK1/2 was impaired in all newborn age groups after stimulation with TLR-specific ligands. Accordingly, after LTA stimulation, the levels of interleukin (IL)-1 beta , IL-6, and IL-8 cytokine production were substantially lower (P<.001) in preterm newborns than in adults. The reduced functional response to bacterial cell wall components appears to be part of the functional immaturity of the neonatal immune system and might predispose premature newborns to bacterial infection.

The bacterial load of Ureaplasma parvum in amniotic fluid is correlated with an increased intrauterine inflammatory response

Ureaplasma spp. are the most frequently isolated microorganisms inside the amniotic cavity and have been associated with spontaneous abortion, chorioamnionitis, premature rupture of the membranes (PROM), and preterm labor (PL). We analyzed 118 samples from amniotic fluid of preterm infants before 34 weeks of gestation by quantitative polymerase chain reaction (qPCR). Bacterial load, Ureaplasma biovar discrimination (Ureaplasma urealyticum and Ureaplasma parvum), and the level of inflammation were correlated with short-term clinical outcome. U. parvum was the predominant biovar, and increased bacterial load was significantly linked to histologic chorioamnionitis, PROM + PL, early-onset sepsis, and bronchopulmonary dysplasia. Furthermore, there was a positive correlation between the amount of U. parvum and the magnitude of inflammatory response inside the amniotic cavity observed by elevated interleukin 8 levels. We postulate that the bacterial load of Ureaplasma spp. measured by qPCR should be determined in studies investigating the potential clinical impact of intrauterine Ureaplasma spp. on the outcome of preterm infants.

Molecular Detection of Late-Onset Neonatal Sepsis in Premature Infants Using Small Blood Volumes: Proof-of-Concept

Background: Conventional blood culture is still the gold standard for sepsis diagnosis but results are not immediately available and pathogens are only detected in approximately 25% of cases. New molecular assays for the detection of blood stream pathogens are promising diagnostic tools. Objectives: The aim of the study was to adapt and evaluate a multiplex PCR system using 100 µl blood. -Methods: 46 blood specimens of very low birth weight infants (818 ± 242 g) with suspected sepsis were analyzed using the Roche SeptiFast MGRADE PCR with a modified DNA extraction protocol and software handling tool for decreased blood volume requirements. Results: In the non-infected group, 5/21 infants had a positive PCR result with coagulase-negative staphylococci. All pathogens detected in the blood culture positive group (n = 15) were also detected by PCR. In addition, 4/6 patients had a positive PCR result in the clinical sepsis group (clinical and laboratory signs of sepsis but negative blood culture). Overall, the PCR was demonstrated to have a higher sensitivity (90.5%; 95%CI 68.2-98.3%) in comparison to blood culture (71.4%; 95%CI 47.7-87.8%) including clinical sepsis cases, even though it had a lower specificity (80.0%; 95%CI 58.7-92.4% versus 100.0%; 95%CI 83.4-100.0%). Conclusions: These first data demonstrate the usability and potential benefit of this multiplex PCR using a modified DNA extraction for the rapid detection of nosocomial sepsis in preterm infants in addition to blood culture.

Nosocomial transmission of respiratory syncytial virus in neonatal intensive care and intermediate care units: a prospective epidemiologic study.

To test the hypothesis that a considerable number of preterm infants acquire respiratory syncytial virus (RSV) within the hospital during the postnatal stay, a prospective epidemiologic survey was performed. Nasopharyngeal swabs were taken twice weekly for a period of 8 weeks from preterm infants, medical/nursing staff, and parents during the peak of RSV season 2007/2008 and tested for RSV by polymerase chain reaction. Of 1002 samples, only 4 tested positive (2 from a patient, 2 from staff). Sequence analyses of the G protein demonstrated that nosocomial transmission did not occurr between these individuals.

Intravenous sildenafil i.v. as rescue treatment for refractory pulmonary hypertension in extremely preterm infants.

BACKGROUND Intravenous sildenafil treatment has recently shown promising results and good tolerability in the treatment of refractory pulmonary hypertension (PH) in term and near-term neonates, while comparable data in preterm infants are still lacking. However, for critically ill preterm infants suffering from PH refractory to conventional treatment, sildenafil may represent a last treatment resort. PATIENTS AND METHODS We reviewed the records of 6 critically ill extremely preterm infants who had suffered from PH refractory to conventional treatment and had obtained intravenous sildenafil after careful consideration as ultima ratio treatment. AIM To describe the responses to sildenafil in terms of hemodynamic and respiratory changes during treatment and outcome. RESULTS 4/6 patients showed resolution of severe PH with full reversal of ductal shunt direction into pure left-to-right shunt within 82 ± 35 h after sildenafil start. Remarkably, 2/6 patients developed pulmonary hemorrhage at a time point when significant improvement of PH had already taken place, both of them survived. Overall 4/6 patients died, two deaths were related to treatment-refractory PH. CONCLUSION Intravenous sildenafil treatment seems effective in improving severe PH and hemodynamic instability in extremely preterm infants with refractory PH. Pulmonary hemorrhage may represent a distinct adverse effect of sildenafil treatment in these patients, presumably due to sudden reversal of ductal shunt. Accordingly, sildenafil should be restricted to most severe and refractory cases in this population.

Significant Reduction of Catheter-associated Blood Stream Infections in Preterm Neonates After Implementation of a Care Bundle Focusing on Simulation Training of Central Line Insertion.

Background: Central line–associated blood stream infections (CLABSIs) are common problems in neonatal intensive care units (NICUs). Implementation of catheter care bundles has been shown to reduce CLABSI rates. We developed a care bundle aiming at establishing a uniform central line insertion technique and improving teaching practices focusing on simulation-based techniques. The purpose of this study was to assess the impact of this care bundle on CLABSI rates in very low birth weight infants (VLBWI). Methods: In September 2010, a CLABSI prevention bundle was introduced in our NICU, consisting of simulation-based standardization and education of a peripherally inserted central catheter insertion technique. Data of all VLBWI admitted to our NICU during 2010–2012 were analyzed. Diagnosis of CLABSI required a positive blood culture in the presence of a central venous catheter and clinical signs of infection. Results: Five hundred twenty-six VLBWI admitted during the study period were included into the analysis. CLABSI rates decreased significantly from 13.9 in 2010 to 9.5 in 2011 and 4.7 in 2012 (P < 0.0001). This significant reduction was true for the overall population and for subgroups separated by birth weight. Distribution of blood culture pathogens revealed a constant absolute and relative decline of infections with coagulase-negative staphylococci from 2010 (n = 43/50, 86%) to 2012 (n = 12/18, 67%), as opposed by a slight increase of Staphylococcus aureus infections (n = 1/50, 2% in 2010 versus n = 2/18, 11% in 2012). Conclusion: Our data provide evidence of a potential effect of simulation-based training of central line placement in decreasing CLABSI rates in VLBWI and encourage its implementation into care bundles.

Preterm infants who later require duct ligation show different vital signs and pH in early postnatal life

The study investigated early postnatal vital signs in very low birthweight (VLBW) infants who later developed patent ductus arteriosus (PDA). We hypothesised that the early postnatal course of vital signs and blood gas variables might differ between infants whose PDA closed spontaneously, those who responded to ibuprofen and those who later required PDA ligation.