Analysis of pediatric sternal fractures using the Kid's Inpatient Database (KID).

PURPOSE: This study aims to determine if sternal fracture is a predictor of discharge requiring additional care and mortality. METHODS: Blunt pediatric trauma admissions (<18 years) in the Kid's Inpatient Database (2016) were included in analysis. Weighted incidence of sternal fracture was calculated and adjusted for using survey weight, sampling clusters, and stratum. Regression analysis was used to identify factors associated with poor outcomes. RESULTS: Annual incidence of sternal fracture in the pediatric blunt trauma population was 0.43 per 100,000. Of 50,076 patients identified, 236 had sternal fractures. The sternal fracture patients were older (median 16 vs 10 years, P < 0.001) and motor vehicle accident was more frequently the mechanism of injury (78% vs 24%, P < 0.001). Common injuries associated with sternal fracture included clavicle fracture (43%), abdominal organ injury (28%), spinal fracture (47%), lung injury (65%), and rib fracture (47%).  Sternal fracture patients were more frequently discharged to receive additional care (22% vs 5%, P < 0.001) and to die of their injuries (3.8% vs 0.9%, P < 0.001). When adjusting for other factors associated with poor outcomes, sternal fracture was not an independent predictor of mortality or discharge to care. CONCLUSIONS: Sternal fracture is a severe injury in the pediatric population, but it is not independently associated with need for a higher level of care after discharge or mortality.

Use of Chest Computed Tomography for Blunt Pediatric Chest Trauma: Does It Change Clinical Course?

INTRODUCTION: Given the concern for radiation-induced malignancy in children and the fact that risk of severe chest injury in children is low, the risk/benefit ratio must be considered in each child when ordering a computed tomography (CT) scan after blunt chest trauma. METHODS: The study included pediatric blunt trauma patients (age, <15 years) with chest radiograph (CR) before chest CT on admission to our adult and pediatric level I trauma center. Surgeons were asked to view the blinded images and reads and indicate if they felt CT was warranted based on CR findings, if their clinical management change based on additional findings on chest CT, and how they might change management. RESULTS: Of the 127 patients identified, 64.6% had no discrepancy between their initial CR and chest CT and 35.4% of the children's imaging contained a discrepancy. The majority of the pediatric and general trauma surgeons felt CT was indicated in 6 of 45 patients based on CR. In 87% of patients with a discrepancy in findings on CR and CT, the majority of surgeons agreed that their management would not change based on the additional information. In the 6 patients in which the CT was considered indicated, 4 of the 6 would have triggered a management change. CONCLUSIONS: Our study suggests that chest CT scans frequently serve as confirmatory diagnostic tools and in the pediatric blunt chest trauma patient and can be withheld in many cases without hindering the management of an injured child.

Standardized irrigation technique reduces intraabdominal abscess after appendectomy.

PURPOSE: The utility of irrigation at the time of appendectomy for acute appendicitis has been debated, with recent studies showing no benefit to irrigation. In our practice, two techniques have been used; one in which irrigation was at the discretion of the surgeon, and one in which irrigation was standardized. The standardized irrigation technique involved large volume (3-12 l) irrigation in small, focused, directed aliquots to achieve optimal dilution. We sought to retrospectively assess whether the standardized large volume irrigation technique was associated with measurably reduced intraabdominal infection. We hypothesized that there would be no difference in intraabdominal infection rate. METHODS: Medical records for cases of appendectomies performed for acute appendicitis, years 2007 through 2017, were reviewed (n = 432). Rate of subsequent abdominal infection was compared between patients who underwent the standardized large volume irrigation technique compared to those who did not using Fisher's exact test; p < 0.05 was considered significant. RESULTS: For patients that underwent the standardized large volume irrigation technique there were no (0/140) subsequent abdominal infections within the study period, compared with a rate of 6.2% (18/292) for all other patients (p value 0.001). Among cases that had a perforated appendix (n = 105), the rates were 0% (0/31) compared to 18.9% (14/74; p value 0.009). CONCLUSIONS: Utilization of a standardized large volume irrigation technique with the objective of serial dilution is associated with a significantly lower rate of subsequent abdominal infection, even among cases with a perforated appendix. Prospective studies are needed to evaluate this technique. LEVEL OF EVIDENCE: Level III. TYPE OF STUDY: Treatment study.

A review of racial/ethnic disparities in pediatric trauma care, treatment, and outcomes.

Health disparities are an increasingly researched topic in the United States. Evidence of disparities found across the spectrum of health care includes pediatric patients. The purpose of this review is to comprehensively summarize disparities among pediatric trauma patients, evaluating both emergency department and hospital treatment and outcomes. Multiple studies describe disparities in a variety of areas of trauma care including emergency department, radiology, surgery, abuse evaluation, and discharge rehabilitation. More concerning, multiple studies report disparities in length of stay, disability, recidivism, and mortality. This review also highlights several gaps in disparity research including specialty care, inclusion of all racial/ethnic groups, and geographic differences. Few of the reviewed studies described disparity interventions; however, research regarding abuse evaluations showed that care guidelines diminished disparity. Trauma care, a routinized patient service, is subject to existing care guidelines and quality improvement programs, and may be the ideal health care setting for disparity intervention. LEVEL OF EVIDENCE: Study type review, level V.

Combined laparoscopic-fluoroscopic technique for primary gastrojejunostomy button tube placement.

BACKGROUND: Gastrojejunostomy (GJ) tubes are frequently used to provide pediatric enteral nutritional support for pediatric patients. Various placement methods have been described, each with attendant advantages and disadvantages. DESCRIPTION OF THE OPERATIVE TECHNIQUE: We present a technique for primary laparoscopic/fluoroscopic GJ button tube placement designed to avoid delay in placement of the jejunal limb, and difficulties associated with endoscopic-assisted and primary fluoroscopic placement. RESULTS: There were 52 gastrojejunostomy button tubes placed via this technique in patients ranging from 3.8 to 90.3 kg in weight. Three postoperative complications were identified; one bowel perforation on postoperative day two, and two tube dislodgements within 30 days. CONCLUSION: The described technique was uniformly effective and was associated with a low complication rate (5.8%).

Peritoneal dialysis catheter placement, outcomes and complications.

PURPOSE: Peritoneal dialysis (PD) is a commonly used method for renal support in pediatric patients and can be associated with the risk of post-surgical complications. We evaluated method of placement of PD catheters with regard to post-surgical complications. METHODS: PD catheters placed at two institutions between 2005 and 2017 were reviewed. Complication rates were evaluated based on method of placement, delayed usage, omentectomy, and patient age using Fisher's exact test, two-sided, with significance set at 0.05. Factors influencing complication were evaluated with multivariate logistic regression and Kaplan-Meier survival analysis. RESULTS: There were 130 patients with 157 catheters placed, ranging in age from 1 day to 23 years. There was no significant difference in complication rate by method of placement or delayed usage. Infants were significantly more likely to experience leakage (21% vs 8%, p 0.036) and hernias (15% vs 5%, p 0.030). Patients that underwent an omentectomy were less likely to require a catheter replacement (7% vs 27%, p 0.004), and the catheters had a significantly higher survival rate (p 0.009). We found that laparoscopic intervention resulted in catheter salvage. Lateral exit sites may be a risk factor for catheter migration in some patients. CONCLUSIONS: Omentectomy is associated with longer PD catheter survival. Laparoscopic salvage of dysfunctional catheters may be a valuable adjunct in management.

Radial umbilical dermatofasciolysis to invert the skin following umbilical herniorrhaphy.

BACKGROUND: Umbilical hernia is a common congenital anomaly, and can result in the appearance of a protuberant umbilicus. In select cases, inversion of the umbilical skin can be impaired by the presence of thickened dermis or fascial remnants of the umbilical stalk. DESCRIPTION OF OPERATIVE TECHNIQUE: After umbilical herniorrhaphy, the skin is everted over the left index finger and radial partial thickness incisions in the fascia and dermis of the undersurface of the umbilicus. The umbilical skin is then inverted and secured to the fascia. CONCLUSION: This operative technique can allow complete inversion of the umbilical skin creating an aesthetically appealing umbilical hernia repair.

The Natural Surfactant Glycerol Monolaurate Significantly Reduces Development of Staphylococcus aureus and Enterococcus faecalis Biofilms.

BACKGROUND: Bacterial biofilms are involved in a large proportion of clinical infections, including device-related infections. Unfortunately, biofilm-associated bacteria are typically less susceptible to antibiotics, and infected devices must often be removed. On the basis of a recent observation that lipid-rich biofilm matrix material is present in early biofilm formation and may protect a population of bacteria from interacting with ordinarily diffusible small molecules, we hypothesized that surfactants may be useful in preventing biofilm development. METHODS: Experimental Staphylococcus aureus or Enterococcus faecalis biofilms were cultivated on surgical suture suspended in a growth medium supplemented with the natural surfactant glycerol monolaurate (GML) or with a component molecule, lauric acid. After 16 h incubation, the numbers of viable biofilm-associated bacteria were measured by standard microbiologic techniques and biofilm biomass was measured using the colorimetric crystal violet assay. RESULTS: Both GML and lauric acid were effective in inhibiting biofilm development as measured by decreased numbers of viable biofilm-associated bacteria as well as decreased biofilm biomass. Compared with lauric acid on a molar basis, GML represented a more effective inhibitor of biofilms formed by either S. aureus or E. faecalis. CONCLUSIONS: Because the natural surfactant GML inhibited biofilm development, resulting data were consistent with the hypothesis that lipids may play an important role in biofilm growth, implying that interfering with lipid formation may help control development of clinically relevant biofilms.

Antibacterial synergy of glycerol monolaurate and aminoglycosides in Staphylococcus aureus biofilms.

Glycerol monolaurate (GML) is a natural surfactant with antimicrobial properties. At ∼0.3 mM, both GML and its component lauric acid were bactericidal for antibiotic-resistant Staphylococcus aureus biofilms. With the use of MICs of antibiotics obtained from planktonic cells, GML and lauric acid acted synergistically with gentamicin and streptomycin, but not ampicillin or vancomycin, to eliminate detectable viable biofilm bacteria. Images of GML-treated biofilms suggested that GML may facilitate antibiotic interaction with matrix-embedded bacteria.

Aminoglycoside inhibition of Staphylococcus aureus biofilm formation is nutrient dependent.

Biofilms represent microbial communities, encased in a self-produced matrix or extracellular polymeric substance. Microbial biofilms are likely responsible for a large proportion of clinically significant infections and the multicellular nature of biofilm existence has been repeatedly associated with antibiotic resistance. Classical in vitro antibiotic-susceptibility testing utilizes artificial growth media and planktonic microbes, but this method may not account for the variability inherent in environments subject to biofilm growth in vivo. Experiments were designed to test the hypothesis that nutrient concentration can modulate the antibiotic susceptibility of Staphylococcus aureus biofilms. Developing S. aureus biofilms initiated on surgical sutures, and in selected experiments planktonic cultures, were incubated for 16 h in 66 % tryptic soy broth, 0.2 % glucose (1× TSBg), supplemented with bactericidal concentrations of gentamicin, streptomycin, ampicillin or vancomycin. In parallel experiments, antibiotics were added to growth medium diluted one-third (1/3× TSBg) or concentrated threefold (3× TSBg). Following incubation, viable bacteria were enumerated from planktonic cultures or suture sonicates, and biofilm biomass was assayed using spectrophotometry. Interestingly, bactericidal concentrations of gentamicin (5 µg gentamicin ml(-1)) and streptomycin (32 µg streptomycin ml(-1)) inhibited biofilm formation in samples incubated in 1/3× or 1× TSBg, but not in samples incubated in 3× TSBg. The nutrient dependence of aminoglycoside susceptibility is not only associated with biofilm formation, as planktonic cultures incubated in 3× TSBg in the presence of gentamicin also showed antibiotic resistance. These findings appeared specific for aminoglycosides because biofilm formation was inhibited in all three growth media supplemented with bactericidal concentrations of the cell wall-active antibiotics, ampicillin and vancomycin. Additional experiments showed that the ability of 3× TSBg to overcome the antibacterial effects of gentamicin was associated with decreased uptake of gentamicin by S. aureus. Uptake is known to be decreased at low pH, and the kinetic change in pH of growth medium from biofilms incubated in 5 µg gentamicin ml(-1) in the presence of 3× TSBg was decreased when compared with pH determinations from biofilms formed in 1/3× or 1× TSBg. These studies underscore the importance of environmental factors, including nutrient concentration and pH, on the antibiotic susceptibility of S. aureus planktonic and biofilm bacteria.

Anoxia inhibits biofilm development and modulates antibiotic activity.

BACKGROUND: Many infections involve bacterial biofilms that are notoriously antibiotic resistant. Unfortunately, the mechanism for this resistance is unclear. We tested the effect of oxygen concentration on development of Staphylococcus aureus biofilms, and on the ability of gentamicin and vancomycin to inhibit biofilm development. MATERIALS AND METHODS: To mimic catheter-associated biofilms, silastic coupons were inoculated with 10(7)S aureus and incubated either aerobically (∼21% O2) or anaerobically (10% CO2, 5% H2, 85% N2) for 16 h at 37°C with varying concentrations of gentamicin and vancomycin. Viable colony-forming units were quantified from sonicated biofilms, and the crystal violet assay quantified biofilm biomass. Metabolomic profiles probed biochemical differences between aerobic and anaerobic biofilms. RESULTS: Control biofilms (no antibiotic) cultivated aerobically contained 8.1-8.6 log10S aureus. Anaerobiasis inhibited biofilm development, quantified by viable bacterial numbers and biomass (P < 0.05). Bactericidal concentrations of gentamicin inhibited biofilm development in normoxia but not anoxia, likely because bacterial uptake of gentamicin is oxygen dependent. The inhibitory effect of vancomycin was more uniform aerobically and anaerobically, although at high bactericidal concentrations, vancomycin effectiveness was decreased under anoxia. There were notable differences in the metabolomic profiles of biofilms cultivated under normoxia versus anoxia. CONCLUSIONS: Compared with aerobic incubation, anaerobiasis resulted in decreased biofilm development, and metabolomics is a promising tool to identify key compounds involved in biofilm formation. The effectiveness of a specific antibiotic depended on its mode of action, as well as on the oxygen concentration in the environment.

Ultrastructure of a novel bacterial form located in Staphylococcus aureus in vitro and in vivo catheter-associated biofilms.

Bacterial biofilms are ubiquitous in nature, industry, and medicine, and understanding their development and cellular structure is critical in controlling the unwanted consequences of biofilm growth. Here, we report the ultrastructure of a novel bacterial form observed by scanning electron microscopy in the luminal vegetations of catheters from patients with active Staphylococcus aureus bacteremia. This novel structure had the general appearance of a normal staphylococcal cell but up to 10 to 15 times as large. Transmission electron microscopy indicated that these structures appeared as sacs enclosing multiple normal-sized (~0.6 µm) staphylococcal forms. Using in vitro cultivated biofilms, cytochemical studies using fluorescent reagents revealed that these structures were rich in lipids and appeared within 15 min after S. aureus inoculation onto clinically relevant abiotic surfaces. Because they appeared early in biofilm development, these novel bacterial forms may represent an unappreciated mechanism for biofilm surface adherence, and their prominent lipid expression levels could explain the perplexing increased antimicrobial resistance of biofilm-associated bacteria.

Clostridium difficile infection in the pediatric surgery population.

PURPOSE: The incidence of Clostridium difficile-associated disease (CDAD) in the adult population doubled in the past decade, with increasing morbidity and mortality; however, little research has been performed in the pediatric population. We characterized C difficile infection in the pediatric population, with emphasis on the surgical population. METHODS: At a university-based children's hospital, we reviewed 231 patient (birth to 18 years of age) records containing a diagnosis of CDAD between January 1, 2002, and December 31, 2008. RESULTS: Clostridium difficile-associated disease incidence increased from 250 per 100,000 hospitalizations in 2002 to 580 per 100,000 hospitalizations in 2008. No fatalities or surgical interventions were attributable to CDAD. Eighty-seven percent of patients received antibiotics within 2 months of diagnosis. Fifty-two percent of patients underwent operative intervention within 2 months of diagnosis; of these, 89% percent received previous antibiotic therapy and 57% were immunosuppressed. The most common antecedent procedures were bone marrow biopsy and line placement for myelodysplastic diseases (40%), followed by renal transplant (11%). CONCLUSIONS: Pediatric CDAD incidence doubled during the study period but was not associated with death or operative intervention. A substantial number of CDAD cases were associated with previous operative procedures, particularly in immunosuppressed patients and those who received prior antibiotics.

Interplay of antibiotics and bacterial inoculum on suture-associated biofilms.

BACKGROUND: Biofilms are often antibiotic resistant, and it is unclear if prophylactic antibiotics can effectively prevent biofilm formation. Experiments were designed to test the ability of high (bactericidal) concentrations of ampicillin (AMP), vancomycin (VAN), and oxacillin (OXA) to prevent formation of suture-associated biofilms initiated with low (10(4)) and high (10(7)) numbers of Staphylococcus aureus. MATERIALS AND METHODS: S. aureus biofilms were cultivated overnight on silk suture incubated in biofilm growth medium supplemented with bactericidal concentrations of AMP, VAN, or OXA. Standard microbiological methods were used to quantify total numbers of viable suture-associated S. aureus. Crystal violet staining followed by spectroscopy was used to quantify biofilm biomass, which includes bacterial cells plus matrix components. To observe the effects of antibiotics on the microscopic appearance of biofilm formation, biofilms were cultivated on glass slides, then stained with fluorescent dyes, and observed by confocal microscopy. RESULTS: In the presence of a relatively low inoculum (10(4)) of S. aureus cells, bactericidal concentrations of AMP, VAN, or OXA were effective in preventing development of suture-associated biofilms. However, similar concentrations of these antibiotics were typically ineffective in preventing biofilm development on sutures inoculated with 10(7)S. aureus, a concentration relevant to contaminated skin. Confocal microscopy confirmed that bactericidal concentrations of AMP, VAN, or OXA inhibited, but did not prevent, development of S. aureus biofilms. CONCLUSION: Bactericidal concentrations of AMP, VAN, or OXA inhibited formation of suture-associated biofilms initiated with low numbers (10(4)), but not high numbers (10(7)), of S. aureus cells.

Relation between antibiotic susceptibility and ultrastructure of Staphylococcus aureus biofilms on surgical suture.

BACKGROUND: Infectious biofilms are recalcitrant to antimicrobial therapy, but the mechanism(s) responsible for the greater resistance are unclear. Experiments were designed to clarify the association between antibiotic resistance and biofilm ultrastructure. METHODS: Staphylococcus aureus was cultivated for 24 h on silk suture, where robust biofilms formed. Initial experiments compared the susceptibilities of planktonic (free-living) cells and mechanically dispersed biofilm cells to ampicillin, oxacillin, and vancomycin. Antibiotics in bactericidal concentrations were then incubated overnight with 24-h biofilms, and subsequent assays determined the viability of cells in mechanically dispersed biofilms, biofilm metabolic capacity and biomass, and biofilm ultrastructure (scanning electron microscopy). RESULTS: Planktonic and biofilm cells had similar intrinsic antibiotic susceptibility. Nonetheless, a stable population of bacteria remained viable after biofilms were incubated with inhibitory drug concentrations, although biofilm metabolic capacity often was not detected, and biomass generally was reduced. Electron microscopy revealed that control (no drug) biofilms consisted primarily of bacterial clusters amid fibrillar elements. Antibiotic-treated biofilms had some staphylococci with smooth cells walls similar to planktonic cells, but other cocci were encased in extracellular material. This material was more abundant in antibiotic-treated than in control biofilms. CONCLUSIONS: In the presence of high antibiotic concentrations, dense extracellular material may inhibit interaction of antibiotics with their bacterial targets.

Gentamicin promotes Staphylococcus aureus biofilms on silk suture.

BACKGROUND: Communities of bacteria, termed biofilms, develop on biotic and abiotic surfaces, including medical devices and surgical suture. Biofilm-associated bacteria are typically recalcitrant to antibiotic therapy, and the effects of antibiotics on microbial biofilms are not clearly understood. There is emerging evidence that under specific conditions, aminoglycosides may actually promote biofilm development. Experiments were designed to study the effects of gentamicin on suture-associated Staphylococcus aureus biofilms. MATERIALS AND METHODS: S. aureus biofilms were formed after 24 h incubation of bacteria with silk suture. Susceptibility of planktonic S. aureus (from broth culture) to gentamicin was compared with the susceptibility of cells from mechanically dispersed S. aureus biofilms. Subinhibitory and inhibitory concentrations of gentamicin were subsequently incubated with intact suture-associated biofilms. S. aureus viability and metabolic capacity were assessed, and biofilm biomass was quantified with crystal violet (binds negatively charged surface molecules) and with the nucleic acid stain Syto 9. Scanning electron microscopy was used to assess the effect of gentamicin on the ultrastructure of suture-associated S. aureus biofilms. RESULTS: Planktonic cells and S. aureus cells from mechanically dispersed biofilms had similar susceptibility to gentamicin. However, after incubation of high concentrations of gentamicin with intact biofilms, high numbers of S. aureus remained both viable and metabolically active; biofilm biomass was increased and biofilm ultrastructure showed staphylococcal cells within copious amounts of extracellular material. CONCLUSION: Gentamicin does not effectively kill S. aureus within intact suture-associated biofilms, and gentamicin also promotes the biomass of S. aureus biofilms.

Role of Staphylococcus aureus protein A in adherence to silastic catheters.

BACKGROUND: Communities of bacteria, termed biofilms, frequently develop on central venous catheters, and bacterial contamination of central venous catheters is the most common cause of nosocomial bloodstream infections. Little is known about the initial events in bacterial adherence to the catheter surface, and experiments were designed to clarify the role of staphylococcal protein A, serum, and immunoglobulin in adherence of Staphylococcus aureus to silastic catheters. We hypothesized that S. aureus protein A in the presence of serum and immunoglobulin would alter S. aureus adherence to silastic catheters. MATERIALS AND METHODS: Three strains of S. aureus with varying expression of staphylococcal protein A were incubated 15 min at room temperature with silastic catheters, and bacterial adherence to the catheter surface was quantified. In addition, the effects of serum, albumin, and purified IgG on bacterial adherence were assessed. RESULTS: Both serum and albumin had an inhibitory effect on S. aureus adherence to the catheter surface, and protein A expression did not appreciably modulate these effects. Purified serum IgG also inhibited S. aureus adherence, with IgG having a greater inhibitory effect on the adherence of an S. aureus strain deficient in protein A compared with an S. aureus strain expressing high levels of protein A. CONCLUSION: S. aureus adherence to silastic catheters was inhibited by whole serum, albumin, and purified IgG. Expression of staphylococcal protein A interfered with IgG mediated inhibition of bacterial binding to the catheter surface. Protein A altered S. aureus adherence to silastic catheters in the presence of immunoglobulin, but not in the presence of serum or albumin.

Bacterial contamination of surgical suture resembles a biofilm.

BACKGROUND: Although much attention is currently directed to studying microbial biofilms on a variety of surfaces, few studies are designed to study bacterial growth on surgical suture. The purpose of this study was to compare the kinetic development of Staphylococcus aureus and Enterococcus faecalis on five surgical suture materials and to clarify factors that might influence this growth. METHODS: Pure cultures of S. aureus and E. faecalis were incubated with five types of suture for four days using either tissue culture medium or a bacterial growth medium. Suture-associated bacteria were quantified daily. In selected experiments, the bacterial growth medium was supplemented with heparin, a substance known to promote S. aureus biofilm formation. The ultrastructure of S. aureus biofilm developing on braided suture was studied with scanning electron microscopy. RESULTS: Staphylococcus aureus and E. faecalis were recovered in greater numbers (typically p < 0.01) from braided than from monofilament suture, and the numbers of bacteria were greater (often p < 0.01) on sutures incubated in bacterial growth medium rather than tissue culture medium. Addition of heparin 1,000 U/mL to silk or braided polyglactin 910 suture incubated three days with S. aureus resulted in greater numbers of bacteria on day one but not on subsequent days. Scanning electron microscopy showed a maturing S. aureus biofilm that developed from small clusters of cells among amorphous material and fibrillar elements to larger clusters of cells that appeared covered by more consolidated extracellular material. CONCLUSIONS: Bacterial growth was favored on braided vs. monofilament suture, and heparin enhanced bacterial adherence after day one, but not at subsequent times. Staphylococcus aureus adhered to suture material and formed a structure consistent with a bacterial biofilm.

Selected factors affecting Staphylococcus aureus within silastic catheters.

BACKGROUND: Catheter-related infections are frequent complications in hospitalized patients, and Staphylococcus aureus is a frequent etiologic agent. Little is known about factors that contribute to the growth and viability of S. aureus within contaminated catheters. MATERIALS AND METHODS: In vitro experiments assessed the ability of S. aureus to adhere to silastic catheter tubing. The effects of heparin, serum, and calcium on initial bacterial adherence were also assessed. Additional experiments quantified the effect of ethanol locking on S. aureus viability within catheter-associated biofilms produced after 48 to 72 h incubation of S. aureus with catheters under conditions of nutrient flow. Scanning electron microscopy visualized the effect of ethanol locking on the morphology of bacterial vegetations adherent to the catheter wall. RESULTS: S. aureus readily adhered (in a dose dependent manner) to silastic catheters incubated with bacteria for 15 min, and adherence was not affected by calcium or heparin (even though heparin adhered to the silastic tubing and S. aureus is known to express heparin-binding proteins). S. aureus adherence was inhibited by serum but not albumin. Ethanol locking (5 min to 24 h) of catheters containing mature 48 to 72 h S. aureus biofilms resulted in no detectable bacterial viability, although scanning electron microscopy revealed similar bacterial vegetations adherent to control and ethanol-treated catheters. CONCLUSION: S. aureus adherence to silastic catheters was inhibited by serum, but the active inhibitory component was not albumin. Ethanol locking efficiently sterilized S. aureus contaminated catheters, although nonviable bacterial vegetations remained on the ethanol-treated catheters.

Echocardiographic assessment of ductal anatomy in premature infants-lessons for device design.

OBJECTIVE: Echocardiographic analysis of patent ductus arteriosus (PDA), proximal left main pulmonary artery (LPA) and descending thoracic aorta (Ao) dimensions in preterm infants who undergo surgical ligation of the PDA. A discussion for percutaneous ductal occlusion in preterm infants. METHODS: Echocardiographic analysis of the LPA diameter, PDA diameter, PDA length, and descending thoracic aorta diameter in 55 preterm infants who underwent surgical ligation of the PDA from 2004 to 2008. Patients were stratified by weight into four groups: those less than 750 g, 751-1,000 g, 1,001-1,250 g, and those greater than 1,250 g. Mean and standard deviation for each structure dimension was calculated in each weight group. Structural dimensions were compared between groups using ANOVA for multiple comparisions. RESULTS: The mean patient weight was 1,018 g (560-2,400 g). The mean ductal length was 4.1 mm (2.5-5.3 mm). The mean ductal diameter was 2.2 mm (1.5-3.6 mm). The mean LPA diameter was 3 mm (1.5-4.5 mm). The mean aortic diameter was 4.3 mm (2.7-7.8 mm). The alpha value for between weight groups for PDA length was 0.21, PDA diameter 0.16, LPA diameter 0.39, and aortic diameter 0.1. DISCUSSION: No statistical significance was seen when comparing structure dimension by weight. This suggests uniform structural dimensions across a broad weight distribution in this patient population. To date, there has been no attempt to standardize dimensions of these vascular structures. The information gathered in this study may be useful in developing an implantable device for ductal occlusion in preterm infants. (ECHOCARDIOGRAPHY 2010;27:575-579).