Active and passive immunization against Pseudomonas aeruginosa infection of burned patients

A 16-part polyvalent pseudomonas vaccine, PEV-01 and an immunoglobulin prepared from plasma from human volunteers vaccinated with PEV-01 were tested in a controlled clinical trial in burned patients at Safdarjang Hospital, New Delhi. The mortality of the burned patients was reduced four-fold in adults and three-fold in children by the immunological treatments. Both immunoglobulin and vaccine increased the concentration of protective antibody. Patients responded to all 16 components in PEV-01. The vaccine caused no toxic side-effects and enhanced the bactericidal activity of polymorphonuclear leucocytes against Pseudomonas aeruginosa.     

Intestinal bacterial translocation in experimentally burned mice with wounds colonized by Pseudomonas aeruginosa.

Translocation of micro-organisms from the gastrointestinal tract may play a role in the pathogenesis of septic complications in severely burned patients. We therefore investigated the influence of burn wound infection with Pseudomonas aeruginosa on translocation in experimentally burned mice. The P. aeruginosa disseminated in 15% of the animals on the second day and in 20% of the animals on the third day postburn in the Pseudomonas-seeded group. Wound colonization with P. aeruginosa, compared with a control group, led to an increased incidence of translocation of Escherichia coli from the GI tract to the spleen (p < 0.005), liver (p < 0.03), lungs (p < 0.005), and peritoneal cavity (p < 0.03) on the second day postburn but not on the third day postburn. On both the second and third days, the number of viable E. coli in the organs in the Pseudomonas-seeded group exceeded that in the organs in the control group. In this model translocation of E. coli from the GI tract played a more important role than did hematogeneous dissemination of P. aeruginosa from the burn wound.     

Inhaled nitric oxide decreases the bacterial load in a rat model of Pseudomonas aeruginosa pneumonia

Gaseous nitric oxide (NO) is bactericidal in vitro. However whether and how it can be used for the treatment of bacterial lung infections in patients with cystic fibrosis is unclear. Here we assessed the bactericidal effect of intermittently inhaled 160 ppm NO for 30 min every 4 h in a Pseudomonas aeruginosa pneumonia model in rats. NO significantly reduced P. aeruginosa colony count in rat lungs but did not affect neutrophil myeloperoxidase function methemoglobin percentage nor plasma nitrite/nitrate levels. This regimen warrants exploration in infected patients with cystic fibrosis.     

A rat model for the study of Pseudomonas aeruginosa enterogenous infection after severe scald

Eighty eight healthy Wistar rats were used in this study. Pseudomonas aeruginosa (serotype IX, labelled with fluorescein isothiocyanate) were fed in suspension (10(9)/ml, 1ml/100g body weight) following a 25-28% full-thickness burn created on the back of animals. The animals were sacrificed at eight different time phases from 1-72 hours after burns. The labelled bacteria were traced in internal organs, the quantitative bacterial cultures of visceral tissues and blood cultures were performed coincidently. The results showed that the labelled bacteria introduced into GI tract could be demonstrated from the internal organs and blood circulation.     

Chronic porcine two-hit model with hemorrhagic shock and Pseudomonas aeruginosa sepsis

BACKGROUND: Sepsis is still a major cause of death despite well-developed therapeutical strategies such as antibiotics and supportive medication. The aim of this study was to characterize the long-term effects of a two-hit porcine sepsis model with a hemorrhagic shock as 'first hit' followed by a Pseudomonas aeruginosa infusion as 'second hit'. MATERIALS AND METHODS: Twelve juvenile healthy pigs were anesthetized and hemodynamically monitored. The two-hit group (n = 6) underwent a hemorrhagic shock with a 50% reduction of the mean arterial pressure and/or cardiac index for 45 min, followed by resuscitation, while the control group (n = 6) received no pretreatment. All chronically catheterized conscious pigs were challenged with a P. aeruginosa infusion (1.6 x 10(7) CFU/kg/h for the first 24 h followed by 1.6 x 10(6) CFU/kg/h for the next 24 h) and observed for another 48 h. RESULTS: The two-hit group showed the following significant differences to the control group: higher APACHE II scores prior to sepsis induction, increased persisting mean pulmonary arterial pressure (MPAP) and pulmonary vascular resistance index (PVRI) during bacterial challenge. In contrast, systemic vascular resistance (SVRI) was reduced at the end of the study. Throughout the observation period, the mean arterial pressure (MAP) was significantly reduced. CONCLUSIONS: The present study shows that the clinical course and hemodynamic effects of a P. aeruginosa sepsis will be aggravated by a preceding hemorrhagic shock during an observation period of 96 h. This two-hit model represents a valid, clinically relevant experimental protocol in sepsis research.     

Synergy between Staphylococcus aureus and Pseudomonas aeruginosa in a rat model of complex orthopaedic wounds.

BACKGROUND: We observed an interaction in animals inoculated concomitantly with Staphylococcus aureus and Pseudomonas aeruginosa during a study of the efficacy of surfactants for disinfection of orthopaedic wounds. This led us to investigate whether synergy could be demonstrated between Staphylococcus aureus and Pseudomonas aeruginosa in a rat model of complex orthopaedic wounds. METHODS: A wire was implanted into the spinous process of a lumbar vertebra of Sprague-Dawley rats through a dorsal incision. Animals were divided into two groups: group one was inoculated with either Staphylococcus aureus or Pseudomonas aeruginosa, and group two received a polymicrobial inoculation with both test organisms in varying concentrations. After inoculation, the wounds were irrigated and closed. On postoperative day 14, all animals were killed and specimens from the wounds were cultured. The number of colony-forming units (CFU) of Staphylococcus aureus or Pseudomonas aeruginosa needed to cause infection in 50% of the animals (ID50) was determined with use of the Reed-Muench method. The infection rate associated with each inoculum combination was calculated, and the two groups were compared. RESULTS: The ID50 was 2.8 x 10(4) CFU for Staphylococcus aureus and 4.8 x 10(5) CFU for Pseudomonas aeruginosa. The combination of 10(3) CFU of Staphylococcus aureus with low concentrations (10(2), 10(3), or 10(4) CFU) of Pseudomonas aeruginosa yielded infection rates that were higher than those found with either organism alone at the same concentrations. The combination of 10(3) CFU of Staphylococcus aureus and 10(3) CFU of Pseudomonas aeruginosa yielded a 75% infection rate, which was significantly higher (p = 0.004) than that associated with 10(3) CFU of either organism alone. As the Pseudomonas aeruginosa concentration was increased (to 10(5), 10(6), and 10(7) CFU), this trend reversed, and the infection rate decreased to 33% (p = 0.004). Low concentrations of Pseudomonas aeruginosa (0 to 10(5) CFU) combined with 10(6) CFU of Staphylococcus aureus yielded infection rates ranging from 83% to 100%. At the higher concentrations of Pseudomonas aeruginosa (10(6) and 10(7) CFU), however, the infection rate again decreased, to 33% (p = 0.005). Only Staphylococcus aureus was isolated from the cultures of the specimens from the animals that had received a polymicrobial inoculum. CONCLUSIONS: Synergy between Staphylococcus aureus and Pseudomonas aeruginosa was demonstrated when low levels of each organism were present in the wound. As the Pseudomonas aeruginosa concentration was increased, the infection rates fell well below what would be anticipated, suggesting that low concentrations of Pseudomonas aeruginosa enhance the ability of Staphylococcus aureus to cause infection in this orthopaedic wound model. At the same time, the presence of Staphylococcus aureus in the ratios tested decreased the rate of infection by Pseudomonas aeruginosa. CLINICAL RELEVANCE: Staphylococcus aureus is a pathogen commonly seen in orthopaedic patients. The pathogenicity of Staphylococcus aureus was shown to be increased in the presence of anaerobic bacteria. This study is the first one that we are aware of that demonstrated synergy between Staphylococcus aureus and Pseudomonas aeruginosa, at low concentrations, in a wound model while at the same time showing that Staphylococcus aureus lowers the rate of Pseudomonas aeruginosa infection.     

Effect of polymyxin B on intestinal bacterial translocation in Pseudomonas aeruginosa wound-colonized burned mice.

Bacterial translocation (BT) from the gastrointestinal tract has been proposed to play a role in the pathogenesis of septic complications in severely burned patients. In a burn model the effect of a subtherapeutic dose of polymyxin B-sulfate (PB) at BT was examined in Escherichia coli-monoassociated mice with Pseudomonas aeruginosa-inoculated burn wounds. The BT incidence and number of translocating microorganisms to the spleen (p less than 0.01), liver (p less than 0.01), lung (p less than 0.05) and heart (p less than 0.05) were diminished significantly in the PB-treated versus the untreated group. Endotoxin in plasma was detectable in one of the 16 PB-treated versus 6 of the 17 control mice (p less than 0.05). The relation of Pseudomonas burn wound inoculation, BT, endotoxin and the endotoxin-neutralizing properties of PB will be discussed.     

大鼠被动型Heymann肾炎的实验研究

目的探索被动型Ｈｅｙｍａｎｎ肾炎（ｐａｓｉｖｅＨｅｙｍａｎｎｎｅｐｈｒｉｔｉｓ，ＰＨＮ）的发病机理与新的治疗途径。方法采用兔抗大鼠肾近曲小管上皮细胞刷状缘微绒毛（ｂｒｕｓｈｂｏｒｄｅｒｍｅｍｂｒａｎｅ，ＢＢＭ）抗血清经Ｗｉｓｔａｒ大鼠尾静脉注射，复制ＰＨＮ模型。考马斯亮兰法检测实验大鼠尿蛋白排泄，免疫组织化学法（ＳＰ法）及计算机图象分析系统检测基质金属蛋白酶９（ｍａｔｒｉｘｍｅｔａｌｏｐｒｏｔｅｉｎａｓｅ９，ＭＭＰ９）及Ⅳ型胶原的表达及其与蛋白尿的关系。观察牛磺酸对该模型的干预作用。结果（１）成功复制了ＰＨＮ模型。（２）ＭＭＰ９在注射抗血清后７天表达明显增高，以３周时为著，ＭＭＰ９的升高与蛋白尿的产生呈线性相关关系（ｒ＝０．９８，Ｐ＜０．０５）；Ⅳ型胶原在２周以后沿基底膜连续性分布中断呈溶解现象。（３）给予牛磺酸的实验大鼠蛋白尿减轻，ＭＭＰ９的表达明显降低，Ⅳ型胶原溶解现象及病理改变也得到了不同程度的改善。结论ＭＭＰ９参与了ＰＨＮ肾小球基底膜的损伤过程；牛磺酸对该模型具有一定的保护作用。     

Comparison of ketamine and pentobarbital anesthesia with the conscious state in a porcine model of Pseudomonas aeruginosa septicemia

Live Pseudomonas aeruginosa (2.5.10(9).kg-1.h-1) were administered to awake (Group A, n = 10) and anesthetized piglets, which were given intravenous ketamine (Group K, 10 mg.kg-1.h-1, n = 8) or pentobarbital (Group P, 15 mg.kg-1.h-1, n = 8). The anesthetized animals were mechanically ventilated. In addition, a pentobarbital group (Group CP, n = 6) and a ketamine control group (Group CK, n = 6) were studied. The mean survival time was 10.5 +/- 3.0 h in Group A, 10.6 +/- 2.8 h in Group K, and 1.8 +/- 1.3 h in Group P. In Group P the arterial pressure, the cardiac output and the systemic vascular resistance declined soon after start of the bacterial infusion, whereas the pulmonary artery pressure increased. The animals died of irreversible circulatory failure. In Group K pronounced pulmonary hypertension and lethal pulmonary edema developed. There was no circulatory failure in Group A, but the animals also died of marked pulmonary edema. Groups CP and CK exhibited stable hemodynamics for a period of 8 h. The results of this study suggest a deleterious effect of pentobarbital on hemodynamics and survival time, and a minor suppressive action of ketamine on the circulation in septicemia. Therefore, data obtained from septic shock studies applying pentobarbital have to be evaluated carefully. Investigation of the effects of gram-negative bacteria or endotoxin should be performed in unanesthetized or, if anesthesia is necessary, in ketamine-anesthetized animals.     

Pseudomonas aeruginosa Septicemia with Gangrene of the Lung and Empyema

The following case report demonstrates the occasional necessity for staged thoracic surgical intervention in the management of a clinical condition commonly associated with high mortality: overwhelming pseudomonas pulmonary infection and septic shock. Intervention included the use of emergency wide-open drainage of gangrene of the lung and empyema, followed by sequential, interval lobectomy.     

Experimental studies of the pathogenesis of infections due to Pseudomonas aeruginosa: immunization using divalent flagella preparations

Flagella preparations of the two antigenic types that make up all the flagella antigens in Pseudomonas aeruginosa were used, individually, to immunize mice. Mice thus immunized were protected when burned and infected with P. aeruginosa. Protection was specific for the flagella antigen of the challenge strain but independent of its somatic antigen. When both antigens were used, together, for immunization, protection was independent of both the flagella and somatic antigen of the challenge strain. These results suggest that a divalent P. aeruginosa 'vaccine' would be of considerable value for immunoprophylaxis in burn patients.     

Pseudomonas aeruginosa infections in the podiatric patient

Pseudomonal infections of the skin, soft tissue, bone, and toe web may often be very difficult to treat. This article reviews the microbiology, pathogenesis, and treatment of pseudomonal infections that are related to podiatric medicine and surgery.     

Xenograft rejection of fetal porcine islet-like cell clusters in the rat: effects of active and passive immunization

The process of islet xenograft rejection is still poorly understood. To elucidate further possible mechanism(s) involved in xenograft rejection, the effect of different immunization protocols was investigated. Fetal porcine islet-like cell clusters (ICCs) were transplanted under the kidney capsule in otherwise untreated rats, rats pre-immunized by s.c. injections of ICCs and in rats passively immunized with immune serum. The rejection process was evaluated with regard to antibody and complement deposition in the graft, as well as to morphology and phenotype of the infiltrating cells. In otherwise untreated animals, a moderate perigraft mononuclear cell infiltrate was seen after 3 days. Graft destruction became evident on day 6 with marked intragraft infiltration by macrophages (ED1 positive), whereas T cells were in the minority and mainly located in the perigraft area. In contrast to the findings in non-immunized rats, the rejection process in pre-immunized rats was characterized by marked intragraft infiltration by macrophages 3 days after transplantation. Moreover, both T cells and macrophages heavily infiltrated the adjacent kidney parenchyma, and major histocompatibility complex (MHC) class II expression in surrounding kidney tubular cells was concomitantly enhanced. Syngeneic rat islets mixed with porcine ICCs escaped the rejection process in non-immunized rats but were affected in pre-immunized animals. Thus, the specificity of the rejection process in non-immunized animals seems to be lost in pre-immunized animals. The early macrophage infiltration was also accelerated in rats passively immunized with immune serum, but no early switch from perigraft to intragraft infiltration or subsequent cellular infiltration in the adjacent kidney parenchyma was seen. Circulating xenoreactive antibodies of the IgG isotype increased after transplantation in normal and otherwise untreated rats. No distinct IgG deposition in the ICC xenografts was observed until day 12 after transplantation in untreated rats, whereas perigraft deposition of IgG was found 1 day after transplantation in pre-immunized rats and in rats given immune serum. No deposition of complement was observed within the ICC xenograft in any of the groups during the observation period. The dependence on T cells, the massive infiltration of macrophages with a unique phenotype, the cellular distribution, and the loss of specificity (bystander killing) of the rejection process in immunized rats suggest that ICC xenograft rejection shares some of its main characteristics with a delayed type hypersensitivity-like (DTH) immune response.