Elastic TPU Mesh as Abdominal Wall Inlay Significantly Reduces Defect Size in a Minipig Model.

Background: The open abdomen with mesh implantation, followed by early reoperation with fascial closure, is a modern surgical approach in difficult clinical situations such as severe abdominal sepsis. As early fascial closure is not possible in many cases, mesh-mediated fascial traction is helpful for conditioning of a minimized ventral hernia after open abdomen. The aim of this study was to evaluate the clinical utilization of an innovative elastic thermoplastic polyurethane mesh (TPU) as an abdominal wall inlay in a minipig model. Methods: Ten minipigs were divided in two groups, either receiving an elastic TPU mesh or a nonelastic polyvinylidene fluoride (PVDF) mesh in inlay position of the abdominal wall. After 8 weeks, mesh expansion and abdominal wall defect size were measured. Finally, pigs were euthanized and abdominal walls were explanted for histological and immunohistochemical assessment. Results: Eight weeks after abdominal wall replacement, transversal diameter of the fascial defect in the TPU group was significantly smaller than in the PVDF group (4.5 cm vs. 7.4 cm; p = 0.047). Immunhistochemical analysis showed increased Ki67 positive cells (p = 0.003) and a higher number of apoptotic cells (p = 0.047) after abdominal wall replacement with a TPU mesh. Collagen type I/III ratio was increased in the PVDF group (p = 0.011). Conclusion: Implantation of an elastic TPU mesh as abdominal wall inlay is a promising approach to reduce the size of the ventral hernia after open abdomen by mesh-mediated traction. However, this effect was associated with a slightly increased foreign body reaction in comparison to the nonelastic PVDF.

[Oligometastasized colorectal cancer-modern treatment strategies]. / Oligometastasierung beim kolorektalen Karzinom ­ moderne Therapiekonzepte.

BACKGROUND: The prognosis of colorectal cancer in UICC stage IV has been improved in the last decades by improvements in interdisciplinary treatment. MATERIAL AND METHODS: Treatment strategies for oligometastasized colorectal cancer are developing more and more into an individualized treatment. An overview of the current literature of modern treatment concepts in oligometastasized colorectal cancer UICC stage IV is given. RESULTS: Surgery still has the supreme mandate in resectable colorectal liver metastases, as neoadjuvant and adjuvant treatment strategies to not provide any benefits for these patients. In marginal or non-resectable stages systemic treatment is superior in these patients depending on the prognostic parameters. Also in curative settings local treatment options should be considered as a reasonable additive tool. An interesting treatment approach for isolated liver metastases and non-resectable colorectal cancer is liver transplantation. CONCLUSION: Irrespective of new developments in treatment strategies for metastasized colorectal cancer, resection of colorectal liver metastases remains the gold standard whenever possible.

MRI Evaluation of an Elastic TPU Mesh under Pneumoperitoneum in IPOM Position in a Porcine Model.

BACKGROUND: The frequency of laparoscopic approaches increased in hernia surgery over the past years. After mesh placement in IPOM position, the real extent of the meshes configurational changes after termination of pneumoperitoneum is still largely unknown. To prevent a later mesh folding it might be useful to place the mesh while it is kept under tension. Conventionally used meshes may lose their Effective Porosity under these conditions due to poor elastic properties. The aim of this study was to evaluate a newly developed elastic thermoplastic polyurethane (TPU) containing mesh that retains its Effective Porosity under mechanical strain in IPOM position in a porcine model. It was visualized under pneumoperitoneum using MRI in comparison to polyvinylidenefluoride (PVDF) meshes with similar structure. METHODS: In each of ten minipigs, a mesh (TPU containing or native PVDF, 10 × 20 cm) was randomly placed in IPOM position at the center of the abdominal wall. After 8 weeks, six pigs underwent MRI evaluation with and without pneumoperitoneum to assess the visibility and elasticity of the mesh. Finally, pigs were euthanized and abdominal walls were explanted for histological and immunohistochemical assessment. The degree of adhesion formation was documented. RESULTS: Laparoscopic implantation of elastic TPU meshes in IPOM position was feasible and safe in a minipig model. Mesh position could be precisely visualized and assessed with and without pneumoperitoneum using MRI after 8 weeks. Elastic TPU meshes showed a significantly higher surface increase under pneumoperitoneum in comparison to PVDF. Immunohistochemically, the amount of CD45-positive cells was significantly lower and the Collagen I/III ratio was significantly higher in TPU meshes after 8 weeks. There were no differences regarding adhesion formation between study groups. CONCLUSIONS: The TPU mesh preserves its elastic properties in IPOM position in a porcine model after 8 weeks. Immunohistochemistry indicates superior biocompatibility regarding CD45-positive cells and Collagen I/III ratio in comparison to PVDF meshes with a similar structure.

Surgical sutures: coincidence or experience?

BACKGROUND: Knotting sutures by hand is still important in daily surgical routine, especially laparotomy closure. The expectation is that hand suturing relies on the experience and subjective estimation of the surgeon. The aim of this study was to investigate whether hand suturing tension is reproducible and if surgical experience influences reproducibility. METHODS: At the annual Congress of the German Association of Surgery, 118 surgeons performed repetitive sutures on a standardized and certified measuring device simulating the final knot of a fascial closure. Each surgeon was asked to perform five identical single knots in a row using the suture tension that each considered ideal. Tension during knotting was measured in Newtons. The surgeons were divided into five subgroups based on surgical experience: group 1, <1 year; group 2, 2-5 years; group 3, 6-10 years; group 4, 11-20 years; and group 5, >30 years. RESULTS: The tension measured at the end of knotting ranged from 0.19 to 10 N. The mean suture tension at endpoint was 3.88 N for group 1 and slightly higher in the other groups, but not significantly different. The overall mean suture tension was 5.43 N and did not correlate with surgical experience. Suture tension was not reproducible. CONCLUSION: Sequential suture tension varied, even among experienced surgeons. The ideal tissue-dependent suture tension has not been defined. Measured values appear to be intuitive, relying on individual feeling rather than the level of experience.

[Rectal perforation : A rare complication following radiotherapy]. / Rektumperforation : Eine seltene Komplikation nach Strahlentherapie.

BACKGROUND: Radiotherapy in the treatment of prostate cancer is well established. Intestinal complications following radiotherapy are divided into acute and chronic toxicity. Chronic complications like perforation and fistula formation to the rectum are rare and difficult to treat. MATERIALS AND METHODS: In case of chronic radiotherapy complications and particularly chronic fistula formation to the rectum, evidence is low. Therefore, an overview of the available literature of surgical therapy strategies is given. RESULTS: Options for the treatment of acute intestinal toxicity are established and therapy algorithms exist. Therapy of acute rectal perforation covers primary suture repair with or without diversion stoma as well as primary rectal resection with or without primary restoring bowel continuity. In chronic rectal lesions and particularly in fistula formation to the rectum, abdominal treatment strategies are preferred with additional interposition of an omental flap or vascularized muscle flap. CONCLUSION: Although evidence for surgical therapy strategies of the rare chronic rectourethral and rectovesical fistula is low, treatment is a real interdisciplinary challenge and should be provided in a specialized center.

Port-site incisional hernia - A case series of 54 patients.

BACKGROUND: The increased use of laparoscopy has resulted in certain complications specifically associated with the laparoscopic approach, such as port-site incisional hernia (PIH). Until today, it is not finally clarified if port-site closure should be performed by fascia suture or not. Furthermore, the optimal treatment strategy in PIH (suture vs. mesh) is still widely unclear. The aim of this study was to present our experience with PIH in two independent departments and to derive possible treatment strategies from these results. METHODS: Between 2003 and 2013, 54 patients were operated due to port-site incisional hernia in two surgical centres. Their data were collected and retrospectively analyzed depending on surgical technique of port-site hernia repair (Mesh repair group, n = 13 vs. Suture only group, n = 41). RESULTS: Port site incisional hernia occurred in 96% (52 patients) after the use of trocars with 10 mm or larger diameter. Patients treated with mesh repair had significantly higher body mass index (BMI) (32 ± 9 vs. 27 ± 4; p = 0.023) and significantly higher rates of cardiac diseases (77% vs. 39%; p = 0.026) than patients in the suture only group. Mean fascial defect size was significantly larger in the Mesh repair group than in the Suture only group (31 ± 24 mm vs. 24 ± 32 mm; p = 0.007) and mean time of operation was significantly longer in patients operated with mesh repair (83 ± 47 min vs. 40 ± 28 min; p < 0.001). There were no significant differences in mean hospital stay (3 ± 4 days; p = 0.057) and hernia recurrence rates (9%; p = 0.653) between study groups. Mean time of follow up was 32 ± 35 months. CONCLUSIONS: In Port sites of 10 mm and larger diameter fascia should be closed by suture, whereas the risk of hernia development in 5 mm trocar placements seems to be a rare complication. Port-site incisional hernia should be treated by suture or mesh repair depending on fascial defect size and the patients' risk factors regarding preexisting deseases and body mass index.

Analysis of adhesion formation of a new elastic thermoplastic polyurethane (TPU) mesh in comparison to polypropylene (PP) meshes in IPOM position.

BACKGROUND: Postsurgical adhesions severely affect the patients' quality of life causing various complications like bowel obstruction or chronic pain. Especially the implantation of alloplastic prostheses in IPOM position for hernia repair carries a high risk of adhesion formation due to the close contact between mesh and viscera. The extent of adhesions mainly depends on the type and textile characteristics of the implanted mesh. The aim of this study was to examine the degree of adhesion formation of a newly developed, elastic thermoplastic polyurethane (TPU) mesh in comparison to polypropylene (PP) meshes in IPOM position in a rabbit model. METHODS: Sixteen female chinchilla rabbits were laparoscopically operated. Two different meshes were placed to the left and the right lower abdominal wall in IPOM position in each rabbit. After 7 or 21 days, midline laparotomy was performed, the degree of adhesion formation was examined by the Diamond score and mesh elongation was measured under a force of 3N. Finally, the abdominal walls were explanted for immunohistochemical and histopathological investigations. RESULTS: TPU meshes showed significantly lower Diamond scores than PP meshes. After explantation, mesh elongation of the TPU mesh was significantly larger than expansion of PP under a force of 3N. Thus, the TPU mesh preserved its elastic properties after 7 and 21 days. The amount of CD68 positive, Ki67 positive and apoptotic cells within the granuloma around the fibers did not show significant differences between the study groups. CONCLUSIONS: The newly developed TPU mesh seems to reduce peritoneal adhesion formation in IPOM position in a rabbit model compared to PP meshes after 7 and 21 days. Immunohistochemistry did not reveal differences in biocompatibility of the two meshes used.

Etiology of Appendicitis in Children: The Role of Bacterial and Viral Pathogens.

BACKGROUND: Although acute appendicitis is the most common cause for abdominal surgery in children, its etiology is still largely unknown. The aim of this study was to evaluate the role of bacterial and viral pathogens for the etiology of appendicitis in children. METHODS: Between 2000 and 2010, 277 children underwent appendectomy in our institution. On this collective, a retrospective study was performed on to identify the presence of bacterial or viral pathogens. RESULTS: Intraoperatively, 39% of cases showed acute, 9% of cases chronic, and 41% of cases ulcerous inflammation. Bowel perforation was found in 7% of cases and four percent of the children had no inflammation of the appendix at all. Escherichia coli was the predominant bacterium with an incidence of 27.4%, followed by streptococci (9.8%). Concerning viral pathogens, adenovirus was the most common with an incidence of 5.4% followed by rotavirus (4.7%). Significant correlations between histopathological findings and present pathogens were found: in cases of bowel perforation there were significantly more infections with E. coli bacteria (32.2%, p < .001), streptococci (12.2%, p < 0.001), and Pseudomonas aeruginosa (6.7%, p < .001) whereas chronic inflammations were accompanied with a significantly elevated rate of yersinia infections (2.5%, p = .016). Acute inflammations were significantly more often associated with campylobacter (1.7%, p = .011) and oxyures infections (6.1%, p < .001). In relation to the patients' age, a significant accumulation of different pathogens was observed. CRP- and leukocyte counts showed differences between viral and bacterial inflammations. CONCLUSIONS: Our data indicates that appendicitis in children might be triggered by bacterial and viral pathogens and that the type of pathogen directly correlates with patient age, type of inflammation, and level of inflammation values. To confirm and further evaluate these findings, additional studies need to be conducted.

Influence of diversion stoma on surgical outcome and recurrence rates in patients with rectovaginal fistula - A retrospective cohort study.

BACKGROUND: Rectovaginal fistula is an extremely distressing condition for the patients. There is still no generally accepted standard surgical treatment strategy. Especially the influence of diversion stoma creation on patients' outcome remains controversial. Thus, the aim of this study was to analyze the influences of diversion stoma on the outcome of patients treated because of rectovaginal fistula with special regard to perioperative complications and recurrence rates. METHODS: Between 2003 and 2013, all patients treated due to rectovaginal fistula in our institutions were retrospectively analyzed. A total of 81 procedures were performed in 62 patients. Procedures were divided into two groups depending on the presence of a diversion stoma or not (diversion stoma, n = 42 vs. no stoma, n = 39). RESULTS: The overall rate of fistula recurrence was 44% without statistical significance in-between the study groups (49 vs. 38%; p = 0.603). Diversion stoma had no influence on complication rates, wound infections or number of operative revisions. Patients treated with diversion stoma had significantly higher ASA-scores (2.6 ± 0.6 vs. 2.1 ± 0.8; p = 0.011), higher rates of malignoma (58 vs. 17%; p = 0.001) and larger sizes of fistula (1.67 ± 0.08 vs. 1.51 ± 0.46 mm; p = 0.012). The in-hospital stay was significantly longer in these patients (30 ± 66 vs. 15 ± 15 days; p = 0.023). CONCLUSIONS: Our data suggest that diversion stoma creation does not influence the outcome of patients with rectovaginal fistula with special regard to rates of fistula recurrence. On the other hand it is mainly used in complex cases of sick patients and larger fistula sizes. Prospective clinical studies need to be conducted to reinforce these findings.

Major Esophageal Dilation After Laparoscopic Adjustable Gastric Banding in Symptomatic Patients: Does It Prevent Effective Weight Loss and How Should It be Treated?

INTRODUCTION: Esophageal dilation (ED) has been described as a long-term complication following laparoscopic adjustable gastric banding (LAGB) with an incidence of 0.5-50%. The purpose of this study was to evaluate the effect of major ED on weight loss and find methods to diagnose ED and possible treatment strategies based on a classification. MATERIALS AND METHODS: We performed a retrospective analysis of all patients undergoing LAGB between 2004 and 2008 in three community-based hospitals. ED was classified in four stages of dilation using gastrografin swallow. We report body mass index (BMI), failure rates and reoperations among these patients, with a mean follow-up period of 6.7 years. RESULTS: Nineteen (18.4%) of 103 patients who underwent LAGB presented with esophageal dilation. Band deflation failed for all nine patients (8.7%) with major ED. The mean BMI at LAGB (BMI 1), revision (BMI 2), and 1 year after conversion (BMI 3) were 45.9±3.2, 42.8±4.9 and 30.3±5.5 kg/m2, respectively. No significant difference was found comparing BMI 1 and BMI 2 (p=0,065, EWL1: 14.2±21.7 kg/m2). In contrast, the weight loss after the revision surgery was significant (p=0.001, EWL2: 67.1±30 kg/m2). No significant difference was found concerning age, gender, ASA, preoperative (LAGB) weight, and mean interval between LAGB and revision comparing patients with major ED (IV) to patients with milder forms (ED I-III). CONCLUSION: ED is a serious long-term complication after LAGB and seems to prevent effective weight loss in stage IV. Furthermore, untreated dilation could cause long-term damage to the esophagus. Therefore, we suggest routine radiographic follow-up after LAGB even in asymptomatic patients and a treatment based on a classification with an early surgical revision for major ED.

Fascial closure after open abdomen: initial indication and early revisions are decisive factors--a retrospective cohort study.

BACKGROUND: The surgical treatment method in which the peritoneal cavity is opened anteriorly and deliberately left open, hence often called "open abdomen" has become the standard of care in damage-control procedures as well as in the management of intra-abdominal hypertension and in severe intra-abdominal sepsis. Whereas open abdomen has been closed in two stages traditionally, a modern trend is to close the fascial layers within the initial hospitalization to avoid complications like enterocutaneous fistula and hernia formation. The aim of this study was to determine crucial factors influencing the possibility of fascial closure after open abdomen. METHODS: Between 2003 and 2013, 355 adult patients were treated with open abdomen in our institution. Their data were collected and retrospectively analyzed. They were divided into two groups depending on fascial closure or not (fascial closure, n = 137 (39%) vs. non-fascial closure, n = 218 (61%)). RESULTS: The patients who reached fascial closure had a significantly higher rate of initially performed open abdomen (97 patients (71%) vs. 118 (54%), p = 0.002) and the periods of time until a second and a third look operation were significantly shorter (2.7 ± 2.5 vs. 4.2 ± 6.6 days, p = 0.021 and 5.6 ± 3.7 vs. 8.5 ± 8.6 days, p = 0.006). Furthermore, the presence of peritonitis (64 patients (47%) vs. 83 patients (38%), p = 0.023) and large bowel resection (74 patients (54%) vs. 90 patients (41%), p = 0.022) were significantly higher in this group. Rates of in-hospital mortality (97 patients (44%) vs. 38 patients (28%), p = 0.002) and the presence of pancreatitis (19 patients (9%) vs. 3 patients (2%), p = 0.013) were significantly higher in the non-fascial closure group. CONCLUSIONS: The probability to reach fascial closure after open abdomen seems to increase when open abdomen is performed initially and when early second and third look operations are performed. The presence of pancreatitis seems to be the only negative prognostic marker concerning fascial closure.

Laparotomy closure using an elastic suture: a promising approach.

BACKGROUND: Midline laparotomy wound failure like burst abdomen remains one of the major complications after abdominal surgery. The use of sutures with a closer resemblance to abdominal wall physiology, like elastic threads, could decrease the risk of these complications occurring. Thus, we evaluated the possibility of using a new elastic thread composed of thermoplastic polyurethane (TPU) as a suture for the closure of midline laparotomies compared to conventionally used polypropylene (PP) in a rabbit model. METHODS: The elastic TPU thread was processed and tensile tests were performed. Twenty female chinchilla rabbits underwent midline laparotomy. They were randomized to a TPU and a PP group depending on the suture used for fascia closure. After 7 or 21 days, the abdominal walls were assessed macroscopically for wound healing complications and were explanted for histopathological investigation. RESULTS: Tensile tests showed a mean elastic elongation of 55.5% and a sufficient material strength of the TPU thread. In animal experiments, there was no difference between the groups at 7 days; however, the TPU suture showed significantly less CD68 positive cells (p < 0.001) and a higher collagen I/III ratio (p = 0.011) than PP did after 21 days. The amount of apoptotic cells was significantly elevated in the TPU group (p = 0.007) after 21 days. No differences were found concerning granuloma size and number of Ki67-positive cells. CONCLUSIONS: The newly developed TPU thread shows promising tensile characteristics. Midline laparotomy closure is feasible and safe in a rabbit model. Immunohistochemistry indicates similar biocompatibility and wound healing after implantation compared to PP after 21 days. To confirm these findings and to proof long-term capability further studies need to be conducted.

Spinal anesthesia for inguinal hernia repair in infants: a feasible and safe method even in emergency cases.

BACKGROUND: Inguinal hernia repair is the most frequently performed surgical procedure in infants and children. Especially in premature infants, prevalence reaches up to 30% in coincidence with high rates of incarceration during the first year of life. These infants carry an increased risk of complications due to general anesthesia. Thus, spinal anesthesia is a topic of growing interest for this group of patients. We hypothesized that spinal anesthesia is a feasible and safe option for inguinal hernia repair in infants even at high risk and cases of incarceration. METHODS: Between 2003 and 2013, we operated 100 infants younger than 6 months with inguinal hernia. Clinical data were collected prospectively and retrospectively analyzed. Patients were divided into two groups depending on anesthesia procedure (spinal anesthesia, Group 1 vs. general anesthesia, Group 2). RESULTS: Spinal anesthesia was performed in 69 infants, and 31 infants were operated in general anesthesia, respectively. In 7 of these 31 infants, general anesthesia was chosen because of lumbar puncture failure. Infants operated in spinal anesthesia were significantly smaller (54 ± 4 vs. 57 ± 4 cm; p = 0.001), had a lower body weight (4,047 ± 1,002 vs. 5,327 ± 1,376 g; p < 0.001) and higher rate of prematurity (26 vs. 4%; p = 0.017) compared to those operated in general anesthesia. No complications related to surgery or to anesthesia were found in both groups. The number of relevant preexisting diseases was higher in Group 1 (11 vs. 3%; p = 0.54). Seven of eight emergent incarcerated hernia repairs were performed in spinal anesthesia (p = 0.429). CONCLUSIONS: Spinal anesthesia is a feasible and safe option for inguinal hernia repair in infants, especially in high-risk premature infants and in cases of hernia incarceration.

Postoperative outcome in premature infants with open abdomen.

BACKGROUND: Premature infants treated with laparostomy in the first days of their life represent a group of complex patients with high morbidity and mortality rates. Laparostomy is a surgical treatment method in which the peritoneal cavity is opened anteriorly and deliberately left open, hence often called "open abdomen". The aim of this study was to analyze crucial factors influencing the postoperative outcome of premature infants treated this way. METHODS: Between March 2002 and August 2012, we treated 40 premature infants with a median gestational age of 29 weeks (range from 24 to 34 weeks) with open abdomen in our institution. Their data were analyzed retrospectively. They were divided into two groups depending on in-hospital survival. RESULTS: Indications for surgery were ileus (n = 16), spontaneous intestinal perforation (n = 11), gastroschisis (n = 8) and necrotizing enterocolitis (NEC, n = 5). The overall in-hospital mortality was 43 % (17 of 40 patients). Postoperative anemia was the only significant factor influencing mortality rates in our patients (10 vs. 14 patients; p = 0.028). Neither the indication of surgery, nor week of gestation, nor birth weight had any significant influence on postoperative survival. Twenty-one of the 23 surviving patients reached fascia closure. CONCLUSIONS: In our study, outcome of premature infants with open abdomen in the first days of their life seems to depend more on an operation and a postoperative course without complications than on the preoperative conditions of the children. Postoperative anemia seems to be a significant negative prognostic marker. Patients reaching fascia closure mainly survive.

Influence of skin closure technique on surgical site infection after loop ileostomy reversal: retrospective cohort study.

BACKGROUND: Intestinal stoma closure is associated with high risk of surgical site infection (SSI) at stoma reversal site. The aim of this retrospective cohort study was to determine the outcome of purse string approximation (PSA) compared to primary linear closure (PLC) of the skin after loop ileostomy reversal. METHODS: Data of 140 patients operated between 2005 and 2012 were analyzed in this two-center-study to determine the outcome of patients with either PSA (n = 44) or PLC (n = 96) after loop ileostomy reversal. RESULTS: Patients in the PSA group were significantly older than in the PLC group (64 ± 15 vs. 57 ± 18; p = 0.026). Cardiac diseases were significantly more present in the PSA group in comparison to the PLC group (59% vs. 38%; p = 0.017). Stoma creation was significantly more often due to malignancy in the PSA group in comparison to the PLC group (68% vs. 50%; p = 0.044). SSI occurred significantly more often in the PLC group in comparison to the PSA group (17% vs. 5%; p = 0.047). CONCLUSIONS: The risk for SSI is lower in patients with PSA in comparison to patients with PLC. In order to diminish SSI we recommend performing a PSA in patients with loop ileostomy reversal.

In vitro and in vivo characteristics of gentamicin-supplemented polyvinylidenfluoride mesh materials.

To reduce infection rates after mesh implantation antibiotic-coated meshes were designed. The aim of the study was to analyze biocompatibility and in vitro efficiency of a modified gentamicin-supplemented polyvinylidenfluoride mesh. Twenty rats were randomized to two groups (PVDF group and Genta group). Mesh material was implanted subcutaneously. Blood samples were taken to determine the gentamicin serum concentration. Seven and 90 days after mesh implantation, animals were euthanized. The inflammatory tissue response was characterized by analyzing the foreign body granuloma. Cellular immune response was analyzed by immunohistochemical investigations. The collagen type I/III ratio was estimated by crosspolarization microscopy. In vitro agar diffusion test, suspension test, and gentamicin release were characterized. Agar diffusion and suspension test showed efficient antibiotic effects of the mesh in vitro. Serum concentrations of gentamicin showed a peak value 1 h postoperatively with a decline within the next day. The total size of the granuloma was significantly smaller in the Genta group compared to the PVDF group at both points of time. Except of a short period of increased expression of CD68 in the Genta group after 7 days, no further difference was found analyzing cellular immune response. The collagen type I/III ratio was widely constant analyzing the two mesh types without significant differences comparing both mesh materials. A significantly decreased foreign body granuloma formation compared to the pure PVDF mesh group was found. In vitro analysis showed efficient antibiotic effects of the Gentamicin supplementation compared to the pure PVDF mesh.

Efficacy of pasteurization conditions for the inactivation of Mycobacterium avium subsp. paratuberculosis in milk.

Mycobacterium avium subsp. paratuberculosis, the causative agent of a chronic enteritis in ruminants (Johne's disease), has been linked to Crohn's disease in humans. This microorganism is shed by infected animals primarily in the feces but is also shed in the milk at much lower levels. Therefore, dairy products from infected animals may be one mode of transmission of this animal pathogen. This study was designed to evaluate the effectiveness of the holder and high-temperature short-time pasteurization standards on the destruction of M. paratuberculosis. One hundred eighty experiments were conducted in this study using a slug-flow pasteurizer unit and a laboratory scale pasteurizer unit. Ultrahigh-temperature milk was inoculated at two concentrations, 10(8) and 10(5) CFU/ml, with three different field strains of M. paratuberculosis. Five different time-temperature combinations were evaluated: 62.7 degrees C for 30 min, 65.5 degrees C for 16 s, 71.7 degrees C for 15 s, 71.7 degrees C for 20 s, and 74.4 degrees C for 15 s. Three replicates of each experiment were run for the pasteurizer unit, time-temperature combination, and strain of M. paratuberculosis. Treatment of milk regardless of bacterial strain or pasteurizer unit resulted in an average 5.0- and 7.7-log kill for the low and high concentrations of inoculum, respectively. Milk treated for cheese production (65.5 degrees C for 16 s) resulted in a much lower and more variable kill. Results from this study indicate that the current U.S. minimum standards for batch and high-temperature short-time pasteurization of grade A milk significantly reduced the survivability of M. paratuberculosis, but some bacteria survived subpasteurization heat treatment of milk used for cheese manufacture.