Prospective assessment of the gastroesophageal microbiome in VLBW neonates.

BACKGROUND: The distal GI microbiota of hospitalized preterm neonates has been established to be unique from that of healthy full-term infants; the proximal GI, more specifically gastroesophageal colonization has not been systematically addressed. We prospectively evaluated early colonization of gastroesophageal portion of the GI tract of VLBW infants. METHODS: This study involved 12 infants admitted to a level III NICU with gestational age (GA) 27 +/- 0.5 weeks and birth weight 1105 +/- 77 grams. The gastroesophageal microbial flora was evaluated using 16S rDNA analysis of aspirates collected in a sterile manner during the first 28 days of life. RESULTS: Bacteria were detected in 9 of the 12 neonates. Ureaplasma was the dominant species in the first week of life, however, staphylococci were the predominant bacteria overall. By the fourth week, Gram (-) bacteria increased in abundance to account for 50% of the total organisms. Firmicutes were present in the majority of the neonates and persisted throughout the 4 weeks comprising nearly half of the sequenced clones. Noticeably, only two distinct species of Staphylococcus epidermidis were found, suggesting acquisition from the environment. CONCLUSIONS: In our neonates, the esophagus and stomach environment changed from being relatively sterile at birth to becoming colonized by a phylogenetically diverse microbiota of low individual complexity. By the fourth week, we found predominance of Firmicutes and Proteobacteria. Bacteria from both phyla (CONS and Gram (-) organisms) are strongly implicated as causes of hospital-acquired infections (HAI). Evaluation of the measures preventing colonization with potentially pathogenic and pathogenic microorganisms from the hospital environment may be warranted and may suggest novel approaches to improving quality in neonatal care.

Fluid flow induces biofilm formation in Staphylococcus epidermidis polysaccharide intracellular adhesin-positive clinical isolates.

Staphylococcus epidermidis is a common cause of catheter-related bloodstream infections, resulting in significant morbidity and mortality and increased hospital costs. The ability to form biofilms plays a crucial role in pathogenesis; however, not all clinical isolates form biofilms under normal in vitro conditions. Strains containing the ica operon can display significant phenotypic variation with respect to polysaccharide intracellular adhesin (PIA)-based biofilm formation, including the induction of biofilms upon environmental stress. Using a parallel microfluidic approach to investigate flow as an environmental signal for S. epidermidis biofilm formation, we demonstrate that fluid shear alone induces PIA-positive biofilms of certain clinical isolates and influences biofilm structure. These findings suggest an important role of the catheter microenvironment, particularly fluid flow, in the establishment of S. epidermidis infections by PIA-dependent biofilm formation.

The effects of shear stress on isolated receptor-ligand interactions of Staphylococcus epidermidis and human plasma fibrinogen using molecularly patterned microfluidics.

Staphylococcus epidermidis is an opportunistic pathogen that has been implicated in hospital-acquired infections, specifically related to implanted intravascular devices. S. epidermidis adhesion is a mechanism of colonization, leading to pathogenesis. Here we demonstrate an easily fabricated and robust parallel microfluidic platform to investigate the physiologically-relevant effects of fluid shear on S. epidermidis adhesion to human fibrinogen (hFg) with increased experimental throughput. In situ molecular patterning using fluid flow boundaries allows for isolation of the molecular interactions in highly defined shear stress environments, while keeping the device operation simple and reproducible. We characterize two modes of attachment of S. epidermidis to hFg coated surfaces. Single colonies adhere in high fractions at low shear stresses (~1 dyne cm(-2)) and adhesion decays with increasing shear. However, clusters of bacteria adhere the highest at median wall shear stress (up to 10 dyne cm(-2)), and adhesion subsequently decays above this critical shear stress. This initial characterization suggests a previously unobserved phenomenon of shear activated cell-cell adhesion in S. epidermidis, which acts to increase the overall attachment strength to hFg. Both of these modes of attachment are dependant upon the presence of intact hFg, indicating that adhesion is resultant from specific molecular recognition between the bacteria and human fibrinogen. This platform provides new insight into complex host-pathogen interactions, and will allow for further investigation of colonization and pathogenesis in more physiologically relevant conditions.

Vein of Galen arteriovenous malformation with PAPVR and use of serial B-type natriuretic peptide levels in the management: a case report and review of the literature.

BACKGROUND: Arteriovenous malformation of the vein of Galen with partial anomalous pulmonary venous return can lead to a critically challenging condition associated with a high morbidity and mortality. CASE REPORT: We report a case of a full term infant born with a vein of Gallen arteriovenous malformation complicated by partial anomalous pulmonary venous return and congestive heart failure where B-type natriuretic peptide was used as a vital tool in clinical assessment and treatment management. CONCLUSIONS: Rapid diagnosis and treatment in infants with complex conditions such as this are imperative to expedite appropriate treatments, preventing long term negative outcome.

B-type natriuretic peptide utilization as an adjunct to management in a case of conjoined twins with pulmonary hypertension.

This article reports a case of pulmonary hypertension in 37-week-gestational-age, pygopagus conjoined twins where B-type natriuretic peptide (BNP) was used as a cost-effective and important tool to aid effective management. Pulmonary hypertension in neonates is associated with high morbidity and mortality and multiplies the challenge of caring for conjoined twins. BNP is a peptide hormone secreted by cardiac ventricles that have undergone stress related to ventricular filling, volume overload, and pressure. BNP is commonly used in adults to assess heart failure, but its utility is less established in infants receiving neonatal intensive care. In this case, BNP testing was used as an adjunct to standard assessments for rapid diagnosis which was critical to expediting appropriate treatment management for these high-risk patients.

Benzyl alcohol and ethanol can enhance the pathogenic potential of clinical Staphylococcus epidermidis strains.

BACKGROUND: Staphylococcus epidermidis is the most frequent cause of health care-associated infections, particularly in neonates and patients with indwelling catheters. The pathogenesis of infections caused by this organism is associated with its ability to form biofilms. We hypothesized that alcohol used in skin disinfectants, as well as preservative in solutions administered through catheters, can enhance biofilm formation by S epidermidis. METHODS: We performed polymerase chain reaction (PCR) analysis to investigate the prevalence of ica locus in a collection of 169 commensal and clinical S epidermidis strains. Using a microtiter plate assay, we examined the effect of ethanol and benzyl alcohol on biofilm production. Quantitative real-time reverse transcriptase PCR analysis evaluated quantitative changes in gene expression. RESULTS: We found that ica-positive but biofilm-negative or low-grade biofilm-positive S epidermidis strains displayed induction or increase in biofilm production after incubation in media supplemented with both ethanol and benzyl alcohol. The expression of the icaADBC operon was up-regulated in the presence of alcohol. CONCLUSION: Our results suggest that biofilm production and, therefore, the pathogen potential of S epidermidis can be induced by alcohol. Considering the routine use of alcohol-based skin disinfectants and benzyl alcohol-containing solutions in hospitals, the alcohol-inducible biofilm phenotype of S epidermidis has potentially profound clinical ramifications.

Variables associated with the early failure of nasal CPAP in very low birth weight infants.

OBJECTIVE: To identify risk factors and neonatal outcomes associated with the early failure of "bubble" nasal continuous positive airway pressure (CPAP) in very low birth weight (VLBW) infants with respiratory distress syndrome (RDS). STUDY DESIGN: Following resuscitation and stabilization at delivery, a cohort of 261 consecutively inborn infants (birth weight < or = 1250 g) was divided into three groups based on the initial respiratory support modality and outcome at 72 hours of age: "ventilator-started" group, "CPAP-failure" group, and "CPAP-success" group. RESULTS: CPAP was successful in 76% of infants < or = 1250 g birth weight and 50% of infants < or = 750 g birth weight. In analyses adjusted for postmenstrual age (PMA) and small for gestational age (SGA), CPAP failure was associated with need for positive pressure ventilation (PPV) at delivery, alveolar-arterial oxygen tension gradient (A-a DO2) >180 mmHg on the first arterial blood gas (ABG), and severe RDS on the initial chest x-ray (adjusted odds ratio [95% CI] = 2.37 [1.02, 5.52], 2.91 [1.30, 6.55] and 6.42 [2.75, 15.0], respectively). The positive predictive value of these variables ranged from 43% to 55%. In analyses adjusted for PMA and severe RDS, rates of mortality and common premature morbidities were higher in the CPAP-failure group than in the CPAP-success group. CONCLUSION: Although several variables available near birth were strongly associated with early CPAP failure, they proved weak predictors of failure. A prospective controlled trial is needed to determine if extremely premature spontaneously breathing infants are better served by initial management with CPAP or mechanical ventilation.

Genetic relatedness of Staphylococcus epidermidis from infected infants and staff in the neonatal intensive care unit.

BACKGROUND: The genetic relatedness of Staphylococcus epidermidis associated with infections in infants and cultured from the hands of nurses was assessed. METHODS: From March 2001 to January 2002, infections caused by S. epidermidis were prospectively monitored. Participating nurses had hand cultures performed quarterly following hand hygiene. Pulsed-field gel electrophoresis was performed to determine genetic relatedness of strains from infants and nurses. RESULTS: During the study period, S. epidermidis caused 42 of 143 (29%) and 26 of 100 (26%) infant infections and was cultured from the clean hands of 51 of 61 (84%) and 53 of 58 (91%) nurses in neonatal intensive care unit (NICU)-1 and NICU-2, respectively. Fifty-eight clones of S. epidermidis were identified among 173 isolates typed: 38 of 173 isolates (22%) were unique clones detected in a single infant (n=10) or nurse (n=28); 42 of 173 (24%) isolates were defined as belonging to small cluster clones (n=15), ie, were detected in 2 to 4 nurses and/or infants; and 93 of 173 (54%) isolates belonged to large cluster clones (n=4), ie, detected in 7 to 64 nurses and/or infants. CONCLUSIONS: These data suggested that most S. epidermidis isolates were shared between infants and nurses. Hand hygiene alone is inadequate to prevent S. epidermidis infections, and additional strategies are needed to prevent cross transmission in NICU populations.

Is the new definition of bronchopulmonary dysplasia more useful?

OBJECTIVE: To determine the incidence of bronchopulmonary dysplasia (BPD) in low birth weight (LBW) infants <1251 g managed with early bubble nasal continuous positive airway pressure (NCPAP) and a gentle ventilation strategy using the newly proposed definition for BPD and the previous definitions. METHODS: Needs for supplemental oxygen and positive pressure (positive pressure ventilation or NCPAP) during initial hospitalization were evaluated in 266 inborn LBW infants (birth weight <1251 g). The data were categorized in three weight groups, <751, 751 to 1000 and 1001 to 1250 g and the incidence of BPD was computed in survivors based on oxygen need at 28 days, 36 weeks postmenstrual age (PMA) and the new severity of BPD criteria, that is, mild BPD: need for supplemental oxygen > or =28 days, but not at 36 weeks PMA; moderate BPD: need for supplemental oxygen > or =28 days and <30% at 36 weeks PMA and severe BPD: need for supplemental oxygen > or =28 days, and >30% at 36 weeks PMA and/or positive pressure at 36 weeks PMA. Further, BPD-associated comorbidities and short-term outcome data during hospitalization were compared among the groups, defined by severity of BPD. RESULTS: Among LBW infants <1251 g, the incidences of BPD at 28 days and 36 weeks PMA were 21.1 and 7.4% respectively. Using the newly defined criteria, the incidences of mild, moderate and severe BPD were 13.5, 4.8 and 2.6%, respectively. In total, 64.6% of these infants had mild BPD and 70.8% weighed <751 g at birth. Associated comorbidities correlated significantly with grades of underlying pulmonary disease. Also, significantly longer hospital stay, discharge at a higher PMA and lower growth velocity was observed with increasing grades of BPD. CONCLUSIONS: The new system for grading the severity of BPD offers a better description of underlying pulmonary disease and correlates with the infant's maturity, growth and overall severity of illness. Whether it will have a role in predicting long-term outcome remains to be determined.

Molecular epidemiology of Serratia marcescens outbreaks in two neonatal intensive care units.

OBJECTIVE: Serratia marcescens can cause serious infections in patients in neonatal intensive care units (NICUs), including sepsis, pneumonia, urinary tract infection, and conjunctivitis. We report the utility of genetic fingerprinting to identify, investigate, and control two distinct outbreaks of S. marcescens. DESIGN: An epidemiologic investigation was performed to control two clusters of S. marcescens infections and to determine possible routes of transmission. Molecular typing by pulsed-field gel electrophoresis determined the relatedness of S. marcescens strains recovered from neonates, the environment, and the hands of healthcare workers (HCWs). SETTING: Two geographically distinct level III-IV NICUs (NICU A and NICU B) in two university-affiliated teaching hospitals in New York City. RESULTS: In NICU A, one major clone, "F," was detected among isolates recovered from four neonates and the hands of one HCW. A second predominant clone, "A," was recovered from four sink drains and one rectal surveillance culture from an asymptomatic neonate. In NICU B, four neonates were infected with clone "D," and three sink drains harbored clone "H." The attributable mortality rate from bloodstream infections was 60% (3 of 5 infants). The antimicrobial susceptibilities of clone F strains varied for amikacin, cefepime, and piperacillin/tazobactam. CONCLUSIONS: S. marcescens causes significant morbidity and mortality in preterm neonates. Cross-transmission via transient hand carriage of a HCW appeared to be the probable route of transmission in NICU A. Sinks did not harbor the outbreak strains. Antimicrobial susceptibility patterns did not prove to be an accurate predictor of strain relatedness for S. marcescens.

Thyroid hormones and gamma interferon specifically increase K15 keratin gene transcription.

Basal layers of stratified epithelia express keratins K5, K14, and K15, which assemble into intermediate filament networks. Mutations in K5 or K14 genes cause epidermolysis bullosa simplex (EBS), a disorder with blistering in the basal layer due to cell fragility. Nonkeratinizing stratified epithelia, e.g., in the esophagus, produce more keratin K15 than epidermis, which alleviates the esophageal symptoms in patients with K14 mutations. Hypothesizing that increasing the cellular content of K15 could compensate for the mutant K14 and thus ease skin blistering in K14 EBS patients, we cloned the promoter of the K15 gene and examined its transcriptional regulation. Using cotransfection, gel mobility shifts, and DNase I footprinting, we have identified the regulators of K15 promoter activity and their binding sites. We focused on those that can be manipulated with extracellular agents, transcription factors C/EBP, AP-1, and NF-kappaB, nuclear receptors for thyroid hormone, retinoic acid, and glucocorticoids, and the cytokine gamma interferon (IFN-gamma). We found that C/EBP-beta and AP-1 induced, while retinoic acid, glucocorticoid receptors, and NF-kappaB suppressed, the K15 promoter, along with other keratin gene promoters. However, the thyroid hormone and IFN-gamma uniquely and potently activated the K15 promoter. Using these agents, we could boost the amounts of K15 in human epidermis. Our findings suggest that treatments based on thyroid hormone and IFN-gamma could become effective agents in therapy for patients with EBS.