Portal Vein Thrombosis Following Splenectomy in Children: Is There a Higher Rate When Using Single-Incision Laparoscopy?

BACKGROUND: Portal vein thrombosis can be a life-threatening complication associated with a splenectomy. Laparoscopic splenectomy has been suggested to cause an increased rate of portal vein thrombosis. Our study evaluated the rate of portal vein thrombosis in pediatric patients who underwent a splenectomy via single-site laparoscopy. METHODS: A retrospective chart review was performed for all patients undergoing laparoscopic splenectomy from November 2012 to July 2019. Demographic data, operative details, postoperative imaging, and patient outcomes were obtained for analysis. Patients were contacted to determine if they had any complications for which they sought medical care elsewhere. RESULTS: There were 78 pediatric patients who underwent laparoscopic splenectomy over the 7-year period. The most common indication was sickle cell disease (70.5%). Single-incision laparoscopy was performed in 61.5% of the cases. Eight were converted to open. Eleven patients (14.1%) had a laparoscopic cholecystectomy performed during the same operation. The overall complication rate was 8.9%. A quarter of our patients had imaging within 1 year of surgery; no portal vein thrombosis was identified. In addition, over half of the patients were recontacted for follow-up questioning. None of the patients surveyed sought medical care elsewhere for a surgery-related complication or sequela of a portal vein thrombus. DISCUSSION: Single-incision laparoscopic splenectomy is a safe approach in children. Using the single-site platform allows the flexibility to perform additional operations, such as cholecystectomy, without the placement of additional ports. This analysis shows that patients undergoing single-incision laparoscopic splenectomy do not have a higher rate for portal vein thrombosis.

Small tunneled central venous catheters as an alternative to a standard hemodialysis catheter in neonatal patients.

BACKGROUND/PURPOSE: Continuous renal replacement therapy (CRRT) is difficult in neonates for several reasons, including problems with catheter placement and maintenance. We sought to compare outcomes between standard hemodialysis catheters (HDC) and 6Fr-tunneled central venous catheters (TC-6Fr). METHODS: We evaluated neonates who received CRRT from December 2013 - January 2018. All patients received CRRT with the Aquadex (Baxter Corporation, Minneapolis, Minnesota) circuit. Data regarding patient demographics, CRRT indication, catheter days, reason for removal, and catheter-specific complications were analyzed. RESULTS: Forty-six catheters were placed in 26 neonates; nine of these were 6Fr-tunneled catheters. The median age and mean weight at CRRT initiation was 9.5 days (IQR 4-31) and 3.5 kg (+/- 0.6 kg), respectively. TC-6Fr lasted longer (median of 28 days vs 10 days, p = 0.02), required fewer revisions (0 vs 0.16/10 catheter days) and were less commonly removed due to bleeding complications (0% vs 10.8%), occlusion (11.1% vs 18.9%), or malposition (0% vs 8.1%); none of these differences were statistically significant. TC-6Fr were associated with higher infection rates (33.3% vs 0%, p = 0.01) than HDC. CONCLUSIONS: TC-6Fr use resulted in less need for catheter revisions and provided longer-lasting vascular access, which may influence infection rates. This catheter provides neonates in need of CRRT more reliable vascular access. LEVEL OF EVIDENCE: III.

Laparoscopic Treatment of Slipping Rib Syndrome in Pediatric Patients.

Background: Slipping rib syndrome (SRS) is an often unrecognized cause of lower chest and upper abdominal pain in children and adolescents. Surgical resection of the cartilaginous portions of the slipping rib often provides permanent pain relief, with the standard surgical approach being an open resection. A minimally invasive approach has not been reported previously; we report a novel laparoscopic technique for the treatment of SRS with satisfactory results. Materials and Methods: A retrospective review of all consecutive pediatric patients who underwent laparoscopic cartilage resection during the year 2019 and open cartilage resection during the year 2018 was included. Following data were recorded: age of patients, length of symptoms, length of procedure, length of cartilage resection, length of stay, resolution of pain, cosmetic acceptability, and postoperative complications. Results: Four patients underwent laparoscopic slipping rib resection without complication during the year 2019. The mean age of symptom onset was 15 (range 14-16) years old, mean length of symptoms was 1.4 (0.5-2.0) years, and mean age at operation was 16.5 (16-18) years old. The average length of the procedure was 72.8 (55-102) minutes, and mean length of cartilage removed was 2.3 (1.9-3.0) cm. Three patients underwent standard open operation during the year 2018. All patients reported complete resolution of their chronic pain at their 6-month follow-up visit. Conclusions: Laparoscopic technique can be used to treat SRS. All patients reported high satisfaction from resolution of chronic pain and the cosmetic appearance of their surgical scars.

Gastrosplenic Fistula without Malignancy Management in a 16-Year-Old Boy.

Gastrosplenic fistula is a very rare entity, most commonly occurring as a distinctive complication of splenic or gastric malignancies, most notably diffuse large B cell lymphoma (DLBCL). Benign gastric ulcer, splenic abscess, and Crohn's disease have also been reported as possible causes. We report a nonmalignant case of 16-year-old male with a gastrosplenic fistula of unclear etiology. The fistulous tract was confirmed by an upper endoscopy and an upper gastrointestinal series. Subsequently, it was surgically managed with a subtotal gastrectomy with "Roux-en-Y" reconstruction and a feeding jejunostomy.

Does the incidence of thoracic aortic injury warrant the routine use of chest computed tomography in children?

BACKGROUND: Thoracic aortic injury is a potentially life-threatening injury associated with rapid deceleration mechanisms. Diagnosis is made by chest computed tomography (CT), which is associated with a risk of radiation-induced malignancy. We sought to determine the incidence of aortic injuries in the pediatric population to weigh against the risk of CT imaging. METHODS: The Pediatric Health Information Systems was queried for children ≤18 years with discharge diagnosis code of thoracic aortic injury (901.0) between December 2004 and 2014. Data abstracted included patient age, gender, diagnosis and procedure codes, and discharge disposition, where available. We also queried for imaging codes to determine what type of chest imaging the child received. RESULTS: Between December 2004 and 2014, 311,850 children were admitted to Pediatric Health Information Systems hospitals with traumatic injury. Of these patients, 46 (0.015%) were coded with a thoracic aortic injury and an accompanying E-code. Twenty-seven patients (58.7%) were male, and the median age was 13 years. The most common mechanism of injury was motor vehicle collision (63%, n = 29). Eighteen hospitals (41.9%) had no patients with a thoracic aortic injury in the 10-year period. In children with a thoracic aortic injury, the mortality rate was 11% (n = 5) and 22 (47.8%) underwent a chest CT during their hospitalization. Forty percent (124,909) of all trauma patients underwent chest CT, with a positive rate for aortic injury of 1.8/10,000. The reported estimated cancer risk from a chest CT scan is 25/10,000 for girls and 7.5/10, 000 in boys, greater than the positive CT rate. CONCLUSION: Thoracic aortic injuries are rare in children in the United States. The risk of cancer associated with screening chest CT is greater than the likelihood of identifying an aortic injury. Therefore, screening chest CT scans are unwarranted in injured children. LEVEL OF EVIDENCE: Therapeutic/Care Management, level IV.

Improving imaging strategies in pediatric appendicitis: a quality improvement initiative.

BACKGROUND: Data from the American College of Surgeons National Surgical Quality Improvement Program identified our hospital as an outlier for preoperative computed tomography (CT) use in the diagnosis of acute appendicitis in children. We performed a quality improvement project to reduce this utilization in favor of ultrasound-based diagnoses (ultrasonography [US]) through creation and implementation of an evidence-based appendicitis algorithm. METHODS: Over a 2-y period (1 y preceding and 1 y following institution of the algorithm), the clinical information of all pediatric patients operated on for suspicion of acute appendicitis following imaging studies in our institution was collated. Basic characteristics were compared before and after protocol implementation using the chi-square test for categorical variables and the nonparametric, independent sample test of medians for numerical variables. Imaging modalities used and clinical outcomes were compared using chi-square analysis. RESULTS: A total of 227 patients (117 preprotocol and 110 postprotocol implementation) were evaluated in our emergency department and operated on for suspicion of acute appendicitis. There were no differences in age, sex, race, or body mass index between the two periods. There were also no differences in length of stay (P = 0.27), acute and perforated appendicitis rates (P = 0.59), negative appendectomy rates (P = 0.40), or postoperative complications (P = 0.19). There was a significant reduction in the utilization of CT, from 65.8% to 22.0%, with a concurrent increase in the utilization of US (P < 0.001). CONCLUSIONS: With the implementation of a standardized, multidisciplinary algorithm, CT utilization was decreased and concurrently US utilization was increased without sacrificing diagnostic accuracy or patient outcomes.

Contrast enhanced ultrasound for the evaluation of blunt pediatric abdominal trauma.

INTRODUCTION: Blunt abdominal trauma is a common problem in children. Computed tomography (CT) is the gold standard for imaging in pediatric blunt abdominal trauma, however up to 50% of CTs are normal and CT carries a risk of radiation-induced cancer. Contrast enhanced ultrasound (CEUS) may allow accurate detection of abdominal organ injuries while eliminating exposure to ionizing radiation. METHODS: Children aged 7-18years with a CT-diagnosed abdominal solid organ injury underwent grayscale/power Doppler ultrasound (conventional US) and CEUS within 48h of injury. Two blinded radiologists underwent a brief training in CEUS and then interpreted the CEUS images without patient interaction. Conventional US and CEUS images were compared to CT for the presence of injury and, if present, the injury grade. Patients were monitored for contrast-related adverse reactions. RESULTS: Twenty one injured organs were identified by CT in eighteen children. Conventional US identified the injuries with a sensitivity of 45.2%, which increased to 85.7% using CEUS. The specificity of conventional US was 96.4% and increased to 98.6% using CEUS. The positive predictive value increased from 79.2% to 94.7% and the negative predictive value from 85.3% to 95.8%. Two patients had injuries that were missed by both radiologists on CEUS. In a 100kg, 17year old female, a grade III liver injury was not seen by either radiologist on CEUS. Her accompanying grade I kidney injury was not seen by one of the radiologist on CEUS. The second patient, a 16year old female, had a grade III splenic injury that was missed by both radiologists on CEUS. She also had an adjacent grade II kidney injury that was seen by both. Injuries, when noted, were graded within 1 grade of CT 33/35 times with CEUS. There were no adverse reactions to the contrast. CONCLUSION: CEUS is a promising imaging modality that can detect most abdominal solid organ injuries in children while eliminating exposure to ionizing radiation. A multicenter trial is warranted before widespread use can be recommended. LEVEL OF EVIDENCE: Level II; Diagnostic Prospective Study.

Acute procedural interventions after pediatric blunt abdominal trauma: A prospective multicenter evaluation.

BACKGROUND: Pediatric intra-abdominal injuries (IAI) from blunt abdominal trauma (BAT) rarely require emergent intervention. For those children undergoing procedural intervention, our aim was to understand the timing and indications for operation and angiographic embolization. METHODS: We prospectively enrolled children younger than 16 years after BAT at 14 Level I Pediatric Trauma Centers over a 1-year period. Patients with IAI who received an intervention (IAI-I) were compared with those who did not receive an intervention using descriptive statistics and univariate analysis; p less than 0.05 was considered significant. RESULTS: Two hundred sixty-one (11.9%) of 2,188 patients had IAI. Forty-five (17.2%) IAI patients received an acute procedural intervention (38 operations, seven angiographic embolization). The mean age for patients requiring intervention was 7.1 ± 4.1 years and not different from the population. Most patients (88.9%) with IAI-I were normotensive. IAI-I patients were significantly more likely to have a mechanism of motor vehicle collision (66.7% vs. 38.9%), more likely to present as a Level I activation (44.4% vs. 26.9%), more likely to have a Glascow Coma Scale less than 14 (31.1% vs. 15.5%), and more likely to have an abnormal abdominal physical examination (93.3% vs. 65.7%) than patients that did not require acute intervention. All patients underwent computed tomography scan before intervention. Operations consisted of laparotomy (n = 21), laparoscopy converted to open (n = 11), and laparoscopy alone (n = 6). The most common surgical indications were hollow viscus injury (HVI) (11 small bowel, 10 colon, 6 small bowel/colon, 2 duodenum). All interventions for solid organ injury, including seven angioembolic procedures, occurred within 8 hours of arrival; many had hypotension and received a transfusion. Procedural interventions were more common for HVI than for solid organ injury (59.2% vs. 7.6%). Postoperative mortality from IAI was 2.6%. CONCLUSION: Acute procedural interventions for children with IAI from BAT are rare, predominantly for HVI, are performed early in the hospital course and have excellent clinical outcomes. LEVEL OF EVIDENCE: Prognostic/epidemiologic study, level III; therapeutic study, level IV.

Focused assessment with sonography for trauma in children after blunt abdominal trauma: A multi-institutional analysis.

INTRODUCTION: The utility of focused assessment with sonography for trauma (FAST) in children is poorly defined with considerable practice variation. Our purpose was to investigate the role of FAST for intra-abdominal injury (IAI) and IAI requiring acute intervention (IAI-I) in children after blunt abdominal trauma (BAT). METHODS: We prospectively enrolled children younger than 16 years after BAT at 14 Level I pediatric trauma centers over a 1-year period. Patients who underwent FAST were compared with those that did not, using descriptive statistics and univariate analysis; p value less than 0.05 was considered significant. FAST test characteristics were performed using computed tomography (CT) and/or intraoperative findings as the gold standard. RESULTS: Two thousand one hundred eighty-eight children (age, 7.8 ± 4.6 years) were included. Eight hundred twenty-nine (37.9%) received a FAST, 340 of whom underwent an abdominal CT. Ninety-seven (29%) of these 340 patients had an IAI and 27 (7.9%) received an acute intervention. CT scan utilization after FAST was 41% versus 46% among those who did not receive FAST. The frequency of FAST among centers ranged from 0.84% to 94.1%. There was low correlation between FAST and CT utilization (r = -0.050, p < 0.001). Centers that performed FAST at a higher frequency did not have improved accuracy. The test performance of FAST for IAI was sensitivity, 27.8%; specificity, 91.4%; positive predictive value, 56.2%; negative predictive value, 76.0%; and accuracy, 73.2%. There were 81 injuries among the 70 false-negative FAST. The test performance of FAST for IAI-I was sensitivity, 44.4%; specificity, 88.5%; positive predictive value, 25.0%; negative predictive value, 94.9%; and accuracy, 85.0%. Fifteen children with a negative FAST received acute interventions. Among the 27 patients with true positive FAST examinations, 12 received intervention. All had an abnormal abdominal physical examination. No patient underwent intervention before CT scan. CONCLUSION: As currently used, FAST has a low sensitivity for IAI, misses IAI-I and rarely impacts management in pediatric BAT. LEVEL OF EVIDENCE: Prognostic and epidemiologic study, level II; diagnostic tests or criteria study, level II; therapeutic/care management study, level III.

Primary laparoscopic gastrojejunostomy tubes as a feeding modality in the pediatric population.

PURPOSE: Outcomes associated with primary laparoscopic gastrojejunal (GJ) tube placement in the pediatric population were evaluated. METHODS: A single-institution, retrospective review examined patients undergoing laparoscopic GJ tube placement between June 2011 and December 2014. Outcomes included gastric feeding tolerance, subsequent fundoplication, complications, and mortality. RESULTS: Ninety laparoscopic GJ tubes were placed. Median follow-up was 342days (interquartile range [IQR]=141-561days). Median patient age was 5months (IQR=3-11months) and weight was 5.2kg (IQR=4-8.4kg). The most common indications for placement were gastroesophageal reflux (n=85, 94.4%) and/or aspiration (n=40, 44.4%). Most common comorbidities included cardiac (n=34, 37.8%) and respiratory (n=29, 32.2%) diseases. The complication rate was 17.8%, including one case of intestinal perforation. Thirty-four (37.7%) patients transitioned to gastric feeding within 1year; time to conversion was 156days (IQR=117-210days); of those, 18.9% patients transitioned to oral feedings. A fundoplication was later performed in 4 children for persistent reflux. Mortality was 23.3% with no procedural-related deaths. CONCLUSION: Primary laparoscopically placed GJ tubes are a reliable means of enteral access for pediatric patients with gastric feeding intolerance. Many of these children are successfully transitioned to gastric and/or oral feedings over time. Further studies are needed to characterize which patients are best served with a GJ tube versus alternatives such as fundoplication. LEVEL OF EVIDENCE: III (treatment) TYPE OF STUDY: Retrospective.

The lost art of the splenorrhaphy.

BACKGROUND: In the case of the hemodynamically unstable child, splenorrhaphy is preferred to splenectomy to avert postsplenectomy sepsis. However, successful splenorrhaphy requires familiarity with the procedure. We sought to determine how many splenectomies or splenorrhaphies for trauma the average pediatric surgeon can be expected to perform during their career. METHODS: The Pediatric Health Information System (PHIS) Database was queried for patients ≤18years coded with an International Classification of Diseases 9th Edition diagnosis code of a splenic injury from 2004 to 2013. Age, gender, grade of splenic injury, and operations performed were extracted. Numbers of pediatric surgeons per hospital were obtained. RESULTS: 9567 children were identified. 2.1% underwent a splenectomy and 0.8% underwent a splenorrhaphy. The average surgeon performed 0.6 (SD=0.6) splenectomies and 0.2 (SD=0.4) splenorrhaphies for trauma. If these rates remain constant over time, the average surgeon would perform 1.8 (SD =1.7) splenectomies and 0.6 (SD =1.1) splenorrhaphies for trauma over a 30-year surgical career. CONCLUSION: Nonoperative management is associated with a host of benefits, but has resulted in a decrease in the experience level of the pediatric surgeons expected to perform an emergency splenectomy or splenorrhaphy when the unusual occasion arises.

The value of official reinterpretation of trauma computed tomography scans from referring hospitals.

INTRODUCTION: Historically, computed tomography (CT) scans of injured children obtained at referring emergency departments were not reinterpreted by trauma center radiologists at our institution, creating a dilemma for trauma physicians: rescan, use the outside interpretation, or interpret scans themselves. In 2010, our radiologists began reinterpreting all referring hospital trauma CT scans; this study examines the effect of that change. METHODS: Transferred patients who had undergone an abdomen/pelvis CT (CTAP) scan between December 2010 and December 2012 were identified in our trauma registry. Pediatric radiologist reinterpretations were compared to referring hospital radiologist reports. RESULTS: We identified 168 patients transferred to our institution with a CTAP. Seventy patients were excluded owing to lack of: complete study, referring hospital interpretation, or reinterpretation. Of the remaining 98 cases, 12 new injuries were identified: 3 splenic and 3 liver injuries, 1 adrenal hematoma, 2 pelvic fractures, 1 spinal fracture, 1 duodenal hematoma and 1 jejunal perforation. Three patients had solid organ injuries upgraded (grade II to III liver laceration; 2 renal lacerations with active extravasation initially missed), and 4 patients downgraded to no injury. CONCLUSION: Reinterpretation of referring hospital CT scans by pediatric radiologists is beneficial to appropriate management of pediatric trauma patients with concern for blunt abdominal trauma.

Laparoscopic Gastrojejunostomy Tube Placement in Infants with Congenital Cardiac Disease.

INTRODUCTION: Gastrojejunostomy (GJ) tubes are an option for durable enteral access for critically ill infants with congenital cardiac disease who struggle with obtaining adequate nutrition. MATERIALS AND METHODS: Infants weighing less than 10 kg with cardiac disease who received placement of a laparoscopic GJ tube from November 2011 to January 2015 were reviewed. The operative technique used an umbilical port for the camera and a single stab incision for the gastric access site. After insufflation to 5-8 mm Hg, the stomach was suspended to the abdominal wall, after which a dilator was maneuvered into a postpyloric position using laparoscopic visualization and fluoroscopy, and a glidewire was passed into the duodenum. The GJ tube was then fluoroscopically threaded over the glidewire; final position was confirmed by contrast injection. RESULTS: There were 32 laparoscopic GJ tube placement operations performed; 7 (21.9%) of these tubes were standard single-unit GJ tubes, and 25 (78.1%) were low-profile gastrostomy tubes modified with a nasojejunal feeding tube threaded through the feeding port. Median patient age was 3.5 months (range, 0.75-11 months), with a median weight of 4.2 kg (range, 2.4-7.4 kg). Congenital defects were varied, including hypoplastic left heart syndrome and pulmonary vein stenosis. Median operative time was 62 minutes for isolated GJ placement (range, 35-114 minutes). There were three postoperative complications, resulting in a 30-day complication rate of 9.4%. Thirty-day mortality was 9.4% with no mortality related to the operation. CONCLUSIONS: Laparoscopic GJ tube placement may be performed safely in infants with cardiac disease and allows these patients to receive adequate nutrition despite intolerance of gastric feeding.

Development of a Streptococcus pneumoniae keratitis model in mice.

BACKGROUND: Streptococcus pneumoniae is a common cause of bacterial keratitis, and models to examine the ocular pathogenesis of this bacterium would aid in efforts to treat pneumococcal keratitis. The aim of this study was to establish a murine model of pneumococcal keratitis. METHODS: The corneas of A/J, BALB/c or C57BL/6 mice were scratched and topically infected with a clinical strain of S. pneumoniae. Slitlamp examination (SLE), enumeration of bacteria in the corneas and histology were performed. RESULTS: Bacteria were recovered from the eyes of A/J mice on postinfection (PI) days 1 [1.96 +/- 0.61 log(10) colony-forming units (CFU)] and 3 (1.41 +/- 0.71 log(10) CFU). SLE scores were significantly higher in the infected A/J mice as compared to the BALB/c or C57BL/6 mice on PI day 3 (p < 0.0001) and steadily increased over time, reaching a maximal value of 3.00 +/- 0.35 on PI day 10. Histopathology revealed stromal edema and the influx of polymorphonuclear leukocytes on PI days 7 and 10, and corneal disruption on PI day 7. CONCLUSIONS: S. pneumoniae keratitis was established in A/J mice, but not BALB/c or C57BL/6 mice.

Cross-sectional study of nasopharyngeal carriage of Streptococcus pneumoniae in human immunodeficiency virus-infected adults in the conjugate vaccine era.

Human immunodeficiency virus (HIV)-infected patients have an increased rate of pneumococcal infections. Within the HIV-infected population, patients with low CD4(+) cell counts have a higher rate of pneumococcal infection. The purpose of our study was to determine pneumococcal carriage and to examine the serotypes carried by HIV-infected patients after the introduction of the conjugate vaccine. Nasopharyngeal swabs were obtained from patients during routine clinic visits. Samples were cultured on blood agar plates with gentamicin and screened for alpha-hemolysis, optochin sensitivity, and bile solubility. Capsular serotypes were determined by multiplex PCR, multibead assay, or latex agglutination. Antibiotic susceptibility was determined by the Etest method. Multilocus sequence typing was also performed. Of the 175 patients enrolled, 120 patients had absolute CD4(+) cell counts above 200/mm(3) and 55 had counts below 200/mm(3). A total of six (3.4%) patients carried pneumococci. All but one of these patients had received the 23-valent pneumococcal vaccine within the previous 5 years. Five of the isolates were serotypes that are not included in the 7-valent conjugate vaccine. Immunization with the pneumococcal polysaccharide vaccine does not prevent colonization in HIV-infected patients; however, the observation of carriage of serotypes not included in the conjugate vaccine may be due to herd immunity and serotype replacement effects in the general population.

Protection from Streptococcus pneumoniae keratitis by passive immunization with pneumolysin antiserum.

PURPOSE: To determine whether passive immunization with pneumolysin antiserum can reduce corneal damage associated with pneumococcal keratitis. METHODS: New Zealand White rabbits were intrastromally injected with Streptococcus pneumoniae and then passively immunized with control serum, antiserum against heat-inactivated pneumolysin (HI-PLY), or antiserum against cytotoxin-negative pneumolysin (psiPLY). Slit lamp examinations (SLEs) were performed at 24, 36, and 48 hours after infection. An additional four corneas from rabbits passively immunized with antiserum against psiPLY were examined up to 14 days after infection. Colony forming units (CFUs) were quantitated from corneas extracted at 20 and 48 hours after infection. Histopathology of rabbit eyes was performed at 48 hours after infection. RESULTS: SLE scores at 36 and 48 hours after infection were significantly lower in rabbits passively immunized with HI-PLY antiserum than in control rabbits (P < or = 0.043). SLE scores at 24, 36, and 48 hours after infection were significantly lower in rabbits passively immunized with psiPLY antiserum than in control rabbits (P < or = 0.010). The corneas of passively immunized rabbits that were examined up to 14 days after infection exhibited a sequential decrease in keratitis, with an SLE score average of 2.000 +/- 1.586 at 14 days. CFUs recovered from infected corneas were not significantly different between each experimental group and the respective control group at 20 or 48 hours after infection (P > or = 0.335). Histologic sections showed more corneal edema and polymorphonuclear leukocyte (PMN) infiltration in control rabbits compared with passively immunized rabbits. CONCLUSIONS: HI-PLY and psiPLY both elicit antibodies that provide passive protection against S. pneumoniae keratitis.

A comparison of pneumolysin activity and concentration in vitro and in vivo in a rabbit endophthalmitis model.

The purpose of this study was to determine whether the in vitro activity and concentration of Streptococcus pneumoniae pneumolysin correlated to the pathogenesis of S. pneumoniae endophthalmitis. Five S. pneumoniae clinical endophthalmitis strains were grown in media to similar optical densities (OD), and extracellular milieu was tested for pneumolysin activity by hemolysis of rabbit red blood cells. Pneumolysin concentration was determined using a sandwich ELISA. Rabbit vitreous was injected with 10(2) colony-forming units (CFU) of 1 of 2 different strains with low hemolytic activity (n = 10 and 12 for strains 4 and 5, respectively) or 1 of 3 different strains with high hemolytic activity (n = 12 per strain). Pathogenesis of endophthalmitis infection was graded by slit lamp examination (SLE) at 24 hours post-infection. Bacteria were recovered from infected vitreous and quantitated. The SLE scores of eyes infected with strains having high hemolytic activity were significantly higher than the scores of those infected with strains having low hemolytic activity (P < 0.05). Pneumolysin concentration in vitro, however, did not correlate with hemolysis or severity of endophthalmitis. Bacterial concentrations from the vitreous infected with 4 of the strains were not significantly different (P > 0.05). These data suggest that pneumolysin hemolytic activity in vitro directly correlates to the pathogenesis of S. pneumoniae endophthalmitis. The protein concentration of pneumolysin, however, is not a reliable indicator of pneumolysin activity.

Factor H binding to PspC of Streptococcus pneumoniae increases adherence to human cell lines in vitro and enhances invasion of mouse lungs in vivo.

Pneumococcal surface protein C (PspC) binds to both human secretory immunoglobulin A (sIgA) and complement factor H (FH). FH, a regulator of the alternative pathway of complement, can also mediate adherence of different host cells. Since PspC contributes to adherence and invasion of host cells, we hypothesized that the interaction of PspC with FH may also mediate adherence of pneumococci to human cells. In this study, we investigated FH- and sIgA-mediated pneumococcal adherence to human cell lines in vitro. Adherence assays demonstrated that preincubation of Streptococcus pneumoniae D39 with FH increased adherence to human umbilical vein endothelial cells (HUVEC) 5-fold and to lung epithelial cells (SK-MES-1) 18-fold, relative to that of D39 without FH on the surface. The presence of sIgA enhanced adherence to SK-MES-1 6-fold and to pharyngeal epithelial cells (Detroit 562) 14-fold. Furthermore, sIgA had an additive effect on adherence to HUVEC; specifically, preincubation of D39 with both FH and sIgA led to a 21-fold increase in adherence. Finally, using a mouse model, we examined the significance of the FH-PspC interaction in pneumococcal nasal colonization and lung invasion. Mice intranasally infected with D39 preincubated with FH had increased bacteremia and lung invasion, but they had similar levels of nasopharyngeal colonization compared to that of mice challenged with D39 without FH.