Results of a randomized trial comparing sequential intravenous/oral treatment with ciprofloxacin plus metronidazole to imipenem/cilastatin for intra-abdominal infections. The Intra-Abdominal Infection Study Group

OBJECTIVE

In a randomized, double-blind, multicenter trial, ciprofloxacin/metronidazole was compared with imipenem/cilastatin for treatment of complicated intra-abdominal infections. A secondary objective was to demonstrate the ability to switch responding patients from intravenous (IV) to oral (PO) therapy.

SUMMARY BACKGROUND DATA

Intra-abdominal infections result in substantial morbidity, mortality, and cost. Antimicrobial therapy often includes a 7- to 10-day intravenous course. The use of oral antimicrobials is a recent advance due to the availability of agents with good tissue pharmacokinetics and potent aerobic gram-negative activity.

METHODS

Patients were randomized to either ciprofloxacin plus metronidazole intravenously (CIP/MTZ IV) or imipenem intravenously (IMI IV) throughout their treatment course, or ciprofloxacin plus metronidazole intravenously and treatment with oral ciprofloxacin plus metronidazole when oral feeding was resumed (CIP/MTZ IV/PO).

RESULTS

Among 671 patients who constituted the intent-to-treat population, overall success rates were as follows: 82% for the group treated with CIP/MTZ IV; 84% for the CIP/MTZ IV/PO group; and 82% for the IMI IV group. For 330 valid patients, treatment success occurred in 84% of patients treated with CIP/MTZ IV, 86% of those treated with CIP/MTZ IV/PO, and 81% of the patients treated with IMI IV. Analysis of microbiology in the 30 patients undergoing intervention after treatment failure suggested that persistence of gram-negative organisms was more common in the IMI IV-treated patients who subsequently failed. Of 46 CIP/MTZ IV/PO patients (active oral arm), treatment success occurred in 96%, compared with 89% for those treated with CIP/MTZ IV and 89% for those receiving IMI IV. Patients who received intravenous/oral therapy were treated, overall, for an average of 8.6 +/- 3.6 days, with an average of 4.0 +/- 3.0 days of oral treatment.

CONCLUSIONS

These results demonstrate statistical equivalence between CIP/MTZ IV and IMI IV in both the intent-to-treat and valid populations. Conversion to oral therapy with CIP/MTZ appears as effective as continued intravenous therapy in patients able to tolerate oral feedings.

Pharmacokinetics of once-daily dosing of gentamicin in surgical intensive care unit patients with open fractures

OBJECTIVE

To compare the first-dose pharmacokinetic parameters of gentamicin 6 mg/kg and 2 mg/kg in stable, nonobese surgical intensive care unit patients with open extremity fractures receiving gentamicin prophylactically.

METHODS

Serial blood samples were obtained over 8 or 24 hours following the first dose of gentamicin. Serum concentrations of gentamicin were measured using fluorescence polarization immunoassay and analyzed by noncompartmental means.

RESULTS

Eleven patients were enrolled, 7 in the 6 mg/kg group and 4 in the 2 mg/kg group. The median (6 vs. 2 mg/kg) age was 29 versus 28 years; serum creatinine 80 versus 88 mumol/L; and APACHE II score 13 versus 10. The mean +/- SD (micrograms/mL) of concentration at the end of the 30-minute infusion (Cmax), concentration 30 minutes after the end of the infusion (Cpk), and concentration at the end of the dosing interval for 6 versus 2 mg/kg were: 35.0 +/- 19.0 versus 10.1 +/- 1.77; 17.0 +/- 2.7 versus 5.4 +/- 0.4, and 0.45 +/- 0.31 versus 0.69 +/- 0.11, respectively. Area under the curve0-infinity (AUC0-infinity), apparent volume of distribution, and half-life were: 89.0 +/- 28.9 versus 26.1 +/- 1.2 mg.h/L, 0.40 +/- 0.10 versus 0.47 +/- 0.14 L/kg, and 4.0 +/- 1.1 versus 4.3 +/- 1.5 h, respectively.

CONCLUSIONS

The first-dose pharmacokinetics of gentamicin 6 mg/kg resulted in a proportional rise in Cmax, Cpk, and AUC0-infinity compared with gentamicin 2 mg/kg in patients with open fractures, but with greater variability.

Alterations of neutrophil responses to tumor necrosis factor alpha and interleukin-8 following human endotoxemia

Interleukin-8 (IL-8), a neutrophil chemoattractant and activating cytokine, has been implicated as a proinflammatory mediator in gram-negative sepsis. In vitro data support the notion of IL-8 as an endothelial adherence inhibitor. To evaluate this issue, we infused six volunteers with reference endotoxin and measured plasma levels of IL-8, neutrophil tumor necrosis factor alpha (TNF-alpha) receptors, TNF-alpha-induced adherence to fibronectin, and neutrophil chemotaxis to IL-8 and other attractants. We found that, at 3 h postinfusion, IL-8 but not TNF-alpha plasma levels were elevated. Neutrophils had shed L-selectin (mean channel fluorescence decrease, 79 +/- 9 to 49 +/- 7; P = 0.0625) and TNF-alpha receptors (decrease in number of receptors per cell, 1,596 +/- 340 to 574 +/- 93; P = 0.004). Cells were chemotactically desensitized to IL-8. TNF-alpha-induced adherence to fibronectin was suppressed from 69% +/- 5% of the phorbol myristate acetate response to 38% +/- 7% (P = 0.0154). These findings support the notion that release of IL-8 into the vascular space may be an in vivo mechanism for suppression of neutrophil accumulation at extravascular sites. L-Selectin loss would reduce the ability of neutrophils to adhere to activated endothelial cells. The specific loss of migratory response to IL-8 would impair neutrophil delivery to areas where IL-8 was the predominant chemoattractant. Loss of TNF-alpha-induced adherence to fibronectin would blunt those responses, including production of oxidants, capacitated by adherence.

The pull-through procedure: technical factors in influencing outcome, with emphasis on pouchitis

BACKGROUND

The purpose of the study was to review those features that we believed to be critical to the successful performance of the ileal pouch-anal anastomosis, or pull-through, procedure, and specifically the complication of pouchitis.

METHODS

The charts of 205 patients who successfully underwent ileal pouch-anal anastomosis procedure were reviewed. No follow-up was available in five patients; therefore, the basis of this report and its analysis was based on 200 consecutive procedures in which at least two of the three surgeons participated. Particular emphasis was placed on continence, particularly nighttime continence. The incidence of pouchitis, either a single episode or intermittent episodes, was surveyed. Particular attention was paid to the level of rectal mucosectomy and anastomosis at the top of the columns of Morgagni, thus retaining the transitional zone.

RESULTS

Only 5% of patients were incontinent in the absence of pouchitis. Twenty-five patients (13%) wore a pad at night, but only nine (5%) wore a pad during the day. Of those patients with pouchitis, 6% (12) have had a single episode and 12% (23) were intermittently on medication. Therapy of pouchitis was usually carried out with ciprofloxacin 500 mg by mouth everyday or twice a day.

CONCLUSIONS

Ileal pouch-anal anastomosis is an excellent procedure, provided technical details are adhered to. Satisfactory outcome with respect to nighttime continence can be achieved with rectal mucosectomy with minimal manipulation and retaining the transitional epithelium, performing the pouch anastomosis at the top of the columns of Morgagni. The incidence of pouchitis is disappointing but need not be inhibiting of either patients or carrying out this life-saving procedure in patients with ulcerative colitis and familial polyposis.

Pathogenesis, prevention, and management of catheter-associated infections

Infection of vascular catheters is one of the leading causes of nosocomial bacteremia in the critically ill patient. Most catheter-associated infections result from exogenous microbial contamination of the catheter at the time of insertion or during use and are endemic. Prevention of catheter-associated infection is based on measures designed to eliminate the potential for microbial contamination of the skin at the catheter insertion site, the catheter hub, tubing connectors, and any inline devices that may be present. Development and implementation of catheter-care protocols for use in the ICU should be effective in preventing catheter infections. The diagnosis of catheter infections is difficult, as there are few signs or symptoms that are specific for an infected catheter. Catheter infection should be suspected in patients who develop fever, chills, and leukocytosis with no other apparent site of infection.

Comparison of empiric aztreonam and aminoglycoside regimens in the treatment of serious gram-negative lower respiratory infections

An open-label, controlled, randomized study was performed to assess the efficacy and safety of combination regimens using either aztreonam or an aminoglycoside control regimen as empiric therapy for suspected aerobic gram-negative bacillary pneumonia or purulent bronchitis. Eighty-four patients, 42 in each arm of the study, were randomly assigned to one of two treatment regimens. The combination aztreonam regimen included aztreonam, 2 gm every 8 hours (q8h), plus either clindamycin, 600 to 900 mg q8h, or nafcillin, 1.5 gm to 2 gm every 6 hours (q6h). The control regimen was one of the following depending on the combination therapy that was designated standard at each of the three study institutions: amikacin, 5 mg/kg q8h, plus cefazolin, 1 gm q8h; amikacin, 500 mg every 12 hours plus mezlocillin, 4 gm q6h; or kinetically dosed tobramycin plus ticarcillin, 3 gm to 4 gm q4h. The two groups were well matched in terms of demographics and clinical characteristics. Among the 84 patients, organisms from the Enterobacteriaceae family accounted for the largest proportion of isolates (44%) including Escherichia coli (13%), Klebsiella species (14%), and Serratia species (9%). Other commonly identified organisms were Pseudomonas aeruginosa (19%), Haemophilus influenzae (15%), Streptococcus pneumoniae (12%), and Staphylococcus aureus (8%). Results of this trial included clinical response rates of 83% in both groups (P = 0.951) and a microbiologic cure rate of 75% in the aztreonam group and 63% in the control group (P = 0.291). In the 59 patients with documented aerobic gram-negative pneumonia, microbiologic eradication rates were 72% in the aztreonam group versus 57% in the control group (P = 0.359). Duration of treatment tended to be shorter in the aztreonam group than in the control group, with a median 10 days of therapy versus 12 days of therapy (P = 0.095), respectively. In addition, the percentage of patients requiring nonstudy antimicrobial agents tended to be lower in the aztreonam group than the control group, involving 21% of patients in the aztreonam group compared with 36% of patients in the control group (P = 0.086). All regimens were well tolerated, and no patient was withdrawn because of adverse reactions to the study medications. Two patients, both in the control group, required dose reduction, which was necessitated by possible aminoglycoside-induced nephrotoxicity. This trial shows that aztreonam is an effective agent with an excellent safety profile when used in combination regimens for the empiric treatment of pneumonia. A well-controlled trial is needed to verify the trend toward shorter hospital stays and a reduced need for additional antimicrobial agents seen with the aztreonam regimen when compared with those receiving aminoglycoside-combination regimens.

Circulating factors contribute to elevation of intracellular cyclic-3',5'-adenosine monophosphate and depression of superoxide anion production in polymorphonuclear leukocytes following thermal injury

We have previously demonstrated that bactericidal activity and superoxide anion (O2-) production are depressed concomitantly in polymorphonuclear leukocytes (PMNs) following thermal injury in a guinea pig model, and the bactericidal defect is related to elevation of intracellular cyclic-3',5'-adenosine monophosphate (cAMP). The purpose of the present investigation was to determine the relationship between elevation of intracellular cAMP and depression of O2- production in PMNs following thermal injury and determine the involvement of circulating factors in the development of these alterations. The kinetics of O2- production and dose responses to formylmethionyl-leucyl-phenylalanine (fMLP) and phorbol myristate acetate (PMA) were depressed in peripheral PMNs following thermal injury in this experimental model. Sera obtained during the period of PMN dysfunction induced depression of O2- production in response to fMLP and elevation of intracellular cAMP in normal PMNs. Pretreatment of normal PMNs with nonsteroidal anti-inflammatory drugs (NSAID; indomethacin or piroxicam) inhibited the elevation of intracellular cAMP mediated by sera from the injured animals but had no effect on the depression of O2- production observed under similar conditions. Treatment of PMNs from injured animals with NSAID under conditions known to reduce the cAMP content of the cells and correct the bactericidal defect did not normalize O2- production. Studies utilizing sera from two thermally injured patients confirmed findings in the guinea pig model of serum-mediated elevation of intracellular cAMP and depression of O2- production in normal PMNs and effects observed with NSAID. These results suggest that circulating factors contribute to the elevation of intracellular cAMP and depression of O2- production in PMNs following thermal injury. Whereas the increase in intracellular cAMP may be involved in the depression of O2- production, our results suggest that there is not a direct link between these alterations.

Guidelines for clinical care: anti-infective agents for intra-abdominal infection. A Surgical Infection Society policy statement

Several antibiotics have been marketed for therapeutic use in intra-abdominal infection. Often, these agents do not provide a sufficient spectrum activity against both facultative and obligate anaerobic gram-negative organisms, or have certain toxic effects that would not otherwise support their use. Guidelines have been developed for selection of antibiotic therapy for intra-abdominal infections and are presented as a statement of the Surgical Infection Society endorsed by the Executive Council. These guidelines are restricted to infections derived from the gastrointestinal tract and deal with those microorganisms commonly seen in such infections. The recommendations are based on in vitro activity against enteric bacteria, experience in animal models, and documented efficacy in clinical trials. Other concerns regarding pharmacokinetics, mechanisms of action, microbial resistance, and safety were also used in the formation of these guidelines. For community-acquired infections of mild to moderate severity, single-agent therapy with cefoxitin, cefotetan, or cefmetazole or ticarcillin-clavulanic acid is recommended. For more severe infections, single-agent therapy with carbapenems (imipenem/cilastatin) or combination therapy with either a third-generation cephalosporin, a monobactam (aztreonam), or an aminoglycoside plus clindamycin or metronidazole is recommended. Regimens with little or no activity against facultative gram-negative rods or anaerobic gram-negative rods are not considered acceptable.

Bactericidal defect of neutrophils in a guinea pig model of thermal injury is related to elevation of intracellular cyclic-3',5'-adenosine monophosphate

PG of the E series inhibit major effector functions of polymorphonuclear leukocytes (PMN) by elevating intracellular cAMP. The present study investigated the involvement of this mechanism in the bactericidal defect of PMN induced by thermal injury in a guinea pig model. Peripheral and peritoneal exudate PMN harvested from thermally injured guinea pigs at 1 or 2 days postburn had decreased bactericidal activity against Pseudomonas aeruginosa and a marked increase in cAMP content. Production of PGE1 by these cells in the absence of exogenous PMN activators was also increased. Treatment of PMN in vitro or in vivo with nonsteroidal anti-inflammatory drugs (indomethacin, ibuprofen, and piroxicam) restored bactericidal activity to normal and concomitantly reduced cAMP content and PGE1 production. A concomitant reduction in cAMP content and PGE1 production was also observed as bactericidal activity of PMN returned to normal under natural conditions during 4 to 7 days postburn. The enhancement of PMN bactericidal activity mediated by NSAID was fully counteracted by purified PGE1, theophylline, and by cAMP itself. These results suggest that the bactericidal defect of PMN induced by thermal injury is related to elevation of cAMP and that PGE1 plays a significant role in this phenomenon.

Bactericidal defect of neutrophils in a guinea pig model of thermal injury is related to elevation of intracellular cyclic-3',5'-adenosine monophosphate

PG of the E series inhibit major effector functions of polymorphonuclear leukocytes (PMN) by elevating intracellular cAMP. The present study investigated the involvement of this mechanism in the bactericidal defect of PMN induced by thermal injury in a guinea pig model. Peripheral and peritoneal exudate PMN harvested from thermally injured guinea pigs at 1 or 2 days postburn had decreased bactericidal activity against Pseudomonas aeruginosa and a marked increase in cAMP content. Production of PGE1 by these cells in the absence of exogenous PMN activators was also increased. Treatment of PMN in vitro or in vivo with nonsteroidal anti-inflammatory drugs (indomethacin, ibuprofen, and piroxicam) restored bactericidal activity to normal and concomitantly reduced cAMP content and PGE1 production. A concomitant reduction in cAMP content and PGE1 production was also observed as bactericidal activity of PMN returned to normal under natural conditions during 4 to 7 days postburn. The enhancement of PMN bactericidal activity mediated by NSAID was fully counteracted by purified PGE1, theophylline, and by cAMP itself. These results suggest that the bactericidal defect of PMN induced by thermal injury is related to elevation of cAMP and that PGE1 plays a significant role in this phenomenon.

Hemodynamic and metabolic alterations during experimental sepsis in young and adult rats

Cecal ligation and puncture (CLP) has been extensively used as a model of sepsis in adult rats. It is not known if the response to sepsis is similar in young and adult rats. This investigation was done to compare hemodynamic and metabolic alterations in young (four to six weeks of age, 60 to 90 grams) and adult (12 to 14 weeks of age, 270 to 340 grams) rats after CLP. In one series of experiments, survival rate was determined for 96 hours, and in other experiments, mean arterial blood pressure (MAP), heart rate (HR), white blood cell count, hematocrit, platelets, plasma glucose, lactate, amino acids, blood urea nitrogen (BUN), blood and peritoneal cultures and resting energy expenditure (REE) were determined eight and 16 hours after CLP. Levels of glycogen in liver and muscle were determined 16 hours after CLP. Mortality rate was similar in young and adult rats. MAP was stable throughout the course of sepsis, with no significant differences between the two groups of rats. HR was higher in young rats at all times studied. The adult rats became hyperglycemic after CLP while the young were hypoglycemic eight hours after CLP but normalized at 16 hours. Plasma lactate and BUN were similar in the two groups of rats, and no alterations were seen during sepsis. Both young and adult rats became hypoaminoacidemic after CLP. The phenylalanine to tyrosine ratio increased in a similar manner during sepsis in both experimental groups. REE was higher in young than in adult rats, but no significant changes were observed during the course of sepsis in either group.(ABSTRACT TRUNCATED AT 250 WORDS)

Nonsteroidal anti-inflammatory drugs correct the bactericidal defect of polymorphonuclear leukocytes in a guinea pig model of thermal injury

We conducted studies to determine the effects of parenteral therapy with indomethacin, ibuprofen, and piroxicam on key immunologic and hematologic alterations induced by thermal injury. Drugs (10-20 mg/kg) or placebo were administered intramuscularly to thermally injured guinea pigs at 3 h postburn and then daily for nine days postburn. All three drugs inhibited production of 6-keto prostaglandin F1 alpha and thromboxane B2 in wound fluid and concomitantly restored the bactericidal activity of polymorphonuclear leukocytes (PMNLs) against Pseudomonas aeruginosa to normal. Indomethacin also increased the proliferative response of splenic lymphocytes to concanavalin A; however, ibuprofen and piroxicam had no effect on this response. None of the drugs affected the extent of systemic complement consumption, thrombocytopenia, leukocytosis, or leukopenia in the injured animals. These results suggest that the PMNL bactericidal defect induced by thermal injury is preventable or reversible and that the mechanisms responsible for this defect are inhibitable by nonsteroidal anti-inflammatory drugs.

Bacterial infectibility of chronically implanted endothelial cell-seeded expanded polytetrafluoroethylene vascular grafts

Vascular prosthetic grafts become more resistant to infection as the interval between implantation and bacteremic challenge increases. Endothelial cell (EC) seeding of such grafts has been shown to improve measurably their ability to resist a bacteremic challenge several weeks after implantation, presumably by reducing the amount of thrombus-free area (TFA) on their luminal surface. However, no investigators have reported the impact of EC seeding on the ability of chronically implanted vascular prostheses to resist a late bacteremic challenge. Bilateral common carotid interposition grafts were placed in 15 adult mongrel dogs with a 4 mm internal diameter, experimental, expanded polytetrafluoroethylene (ePTFE) prosthesis. One animal died shortly after operation and the grafts in two dogs thrombosed, thereby leaving 12 animals with at least one patent graft for subsequent study. At a mean interval of 45 weeks after implantation, five dogs (seven patent grafts) were challenged with an intravenous infusion of 3 X 10(8) radiolabeled Staphylococcus aureus; bacterial adherence and the TFA of the graft's luminal surface were determined for each of the patent grafts. There was no statistically significant difference in bacterial adherence or TFA between EC-seeded and control grafts. At a mean interval of 53 weeks after implantation, the remaining seven dogs (14 patent grafts) received a similar bacterial infusion and the animals were allowed to recover. Five days later, the grafts were harvested and cultured. Once again, there was no significant difference in the infectibility of EC-seeded vs. control grafts.(ABSTRACT TRUNCATED AT 250 WORDS)

Opsonization of bacteroides by the alternative complement pathway reconstructed from isolated plasma proteins

Opsonization of clinical isolates of B. fragilis and B. thetaiotaomicron with the six isolated proteins of the alternative complement pathway under physiological conditions resulted in considerable C3 deposition on the bacterial surfaces. The time course of C3 deposition was similar to that observed in EGTA-serum; however, the magnitude of C3 deposition was twofold greater in EGTA-serum. Opsonization of the bacteria with the isolated alternative pathway proteins failed to promote adherence, uptake, or killing by polymorphonuclear leukocytes, whereas opsonization of the bacteria with EGTA-serum facilitated these events. The difference in opsonic capacity of isolated proteins and EGTA-serum was not related to the quantitative difference in C3 deposition, because repeated opsonization of the bacteria with isolated proteins resulting in C3 deposition comparable to that observed in EGTA-serum only minimally increased adherence of the bacteria to polymorphonuclear leukocytes. SDS-PAGE and autoradiographic analysis of C3 extracted from bacteria opsonized with isolated proteins or EGTA-serum using methylamine and SDS demonstrated that the predominant form of C3 bound by ester bonds under both sets of conditions was iC3b. A low molecular weight C3 cleavage fragment was detected in extracts from bacteria opsonized with isolated proteins, but it accounted for only a minor fraction of the bound C3. The results of our study demonstrate that the early phase of opsonization involving activation of the alternative pathway by B. fragilis and B. thetaiotaomicron and resultant C3 deposition on the bacterial surfaces does not require auxiliary serum factors, but the effector phase of opsonization of these bacteria involving recognition of bacteria-bound C3 by polymorphonuclear leukocytes and the induction of phagocytosis and intracellular killing is dependent on such factors. Natural IgM antibodies serve as auxiliary factors is opsonization of B. thetaiotaomicron by the alternative pathway, whereas additional serum factors are required for alternative pathway-mediated opsonization of B. fragilis.

The effect of indomethacin on muscle and liver protein synthesis and on whole-body protein degradation during abdominal sepsis in the rat

It has been recently suggested that increased muscle protein degradation during injury or infection is at least partially mediated by the increased production of prostaglandin E2 in muscle, and some have suggested that cyclooxygenase inhibitors might decrease protein loss in injured or septic patients. In these experiments, fractional synthesis rates of mixed muscle and liver protein and whole-body tyrosine flux were measured by constant intravenous infusion of tyrosine labeled with carbon 14 in 17 rats with sham operations and 15 severely septic rats with or without indomethacin treatment (20 mg/kg/d). Fractional synthesis rates in muscle and liver were decreased in late sepsis and were lowest in the septic group receiving indomethacin. Unlike the fractional synthesis rate, which was affected by indomethacin in septic rats only, tyrosine flux was significantly lower in indomethacin-treated rats with sham operations and those with sepsis. Although indomethacin reduced total-body protein breakdown during sepsis, it was also associated with lower plasma albumin levels and with decreased protein synthesis in muscle and liver at a time when the survival of the septic host may be dependent on its ability to produce new protein for a variety of vital functions. These results do not support the use of indomethacin in sepsis.

Temporal relationships among immunologic alterations in a guinea pig model of thermal injury

Temporal relationships among various humoral and cellular alterations of host defense mechanisms were investigated in a guinea pig model of thermal injury during three weeks after burning. Reduction in serum concentration of C3 and fixation of C3 on Pseudomonas aeruginosa, presence of activated C3 in plasma, and elevations in levels of 6-ketoprostaglandin F1 alpha and thromboxane B2 in wound fluid were observed at 3-6 hr after burning. These alterations were accompanied by reduction in intrinsic bactericidal activity of polymorphonuclear neutrophils (PMNs) against P. aeruginosa, suppression of bactericidal activity of PMNs by serum, and decreased blood clearance of P. aeruginosa. All parameters returned to normal values by seven to nine days after burning. Proliferative responses of splenic lymphocytes to T cell mitogens were depressed at four days after burning and were maximally reduced at eight days. These data support the concept that there is a continuum of immunologic alterations resulting from thermal injury and that consumption of complement and increase in arachidonic acid metabolism are early events.

Liver resection. A comparison using the Nd-YAG laser, an ultrasonic surgical aspirator, or blunt dissection

Before gaining wide acceptance, possible surgical tools should be compared with the standard ones. This study, therefore, compared the Nd-YAG laser and the CUSA with the standard blunt dissection technique for liver resection in 24 dogs (8 in each group). Using a noncontact technique, the Nd-YAG laser was used for cutting as well as coagulation. The Nd-YAG laser or the CUSA reduced the resection time, with the laser being the faster of the two, and was accompanied by a probable but not significant decrease in perioperative blood loss. The CUSA delineated the blood vessels and bile ducts and gave superior control. It also caused significantly less tissue damage on light and electron microscopic examination than the other two methods. Cultures taken 1 week after operation showed that the risk of bacterial infection correlated well with the extent of tissue necrosis and was significantly greater after use of the Nd-YAG laser than after use of the CUSA. The numbers of animals are small and the conclusions should be tempered by caution, but it appears that the CUSA, but not the Nd-YAG laser, may improve the results of elective liver resection.

Effect of Intralipid on clearance and organ uptake of bacteria in intra-abdominal sepsis in rats

Although infusion of Intralipid has been reported to block reticuloendothelial system (RES) function, it is unclear if this is true at rates used clinically. This study investigates the effect of Intralipid, infused at a rate providing about half of the non-protein caloric needs, on survival and bacterial clearance in septic rats. Continuous infusion of Intralipid (0.9 g/100 g bw/d) or saline (controls) was started immediately after induction of hyperdynamic intra-abdominal sepsis (bacterial agents: E. coli, B. thetaiotamicron). RES function was studied by means of intravenous injection of Selenium-labelled, viable E. coli after 24 or 48 h. Compared to the saline-treated controls, Intralipid did not cause any change in clearance from blood or localisation to liver, spleen or lungs. The 24 and 48 h survival rates were about 80 and 65%, respectively, and similar in the two groups. It is concluded that infusion of Intralipid at a rate close to that used clinically did not impair survival or bacterial clearance in rats with gram-negative sepsis.

Bacterial adherence to endothelial-seeded polytetrafluoroethylene grafts

Since infections of an arterial prosthesis pose a serious threat to life and limb, efforts to produce a graft that is resistant to hematogenous bacteremia continue. We studied the effect of endothelial seeding on bacterial adherence to polytetrafluoroethylene grafts in a canine model. Enzymatically derived venous endothelial cells were seeded in 10 cm long, 4 mm inner diameter polytetrafluoroethylene grafts, which were then implanted as carotid interpositions opposite contralateral unseeded controls. After 4 to 8 weeks, each dog received an intravenous infusion of 3 X 10(8) radiolabeled Staphylococcus aureus. Seeded grafts had significantly fewer adherent viable bacteria than had control grafts (mean, 432 versus 989; p less than 0.05) and significantly fewer radiolabeled bacteria (mean, 2 X 10(5) versus 8 X 10(5); p less than 0.05). Seeded grafts also had significantly more thrombus-free, luminal surface area than had control grafts (mean, 72% versus 40.6%; p less than 0.05). Scanning electron microscopy and autoradiography of seeded grafts confirmed that the sites of bacterial adherence largely corresponded to accumulations of surface thrombus. In this experiment, endothelial seeding appeared to protect against bacterial adherence after a hematogenous challenge 4 to 8 weeks after implantation by reducing luminal thrombi.

A possible beneficial effect of metronidazole in reducing TPN-associated liver function derangements

Cholestasis and fatty infiltration of the liver are common complications of total parenteral nutrition (TPN). Following a recent suggestion that TPN-associated liver function derangements may be related to intestinal overgrowth of anaerobic bacteria, the effect of metronidazole on hepatic dysfunction during TPN in rats was investigated. After 5 days of TPN with either amino acids and glucose or amino acids with glucose and fat, all groups exhibited a mild weight gain, positive nitrogen balance, increased liver weight, increased liver:body weight ratio, increased levels of liver enzymes, and increased hepatic lipid content. The administration of metronidazole at 15 mg/kg/day significantly decreased the hepatic lipid content from 0.077 g fat/g liver for controls to 0.053 g fat/g liver. The efficacy of metronidazole in reducing hepatic fat accumulation during nutritionally effective and adequate TPN in rats suggests the possible involvement of anaerobic bacterial flora of the intestinal tract, at least in part, in the pathogenesis of TPN-associated liver function derangements. However, the various biochemical and morphological expressions of these changes and the discrepancy between unchanged liver weight, liver:body weight ratio, liver enzymes, and the improved hepatic fat content suggest multifactorial mechanisms for TPN-related liver damage.

Theoretical interrelationships among immunologic and hematologic sequelae of thermal injury

A hypothesis of possible interrelationships among immunologic and hematologic sequelae of thermal injury is presented. It is postulated that there are definable pathways involving series of abnormalities with multiple interconnections among these pathways. The initiating step of each pathway should be amenable to blockade. Such blockade would theoretically circumvent the occurrence of the abnormalities or lessen their severity and thereby preserve host resistance.

Activation of Hageman factor by lipopolysaccharides of Bacteroides fragilis, Bacteroides vulgatus, and Fusobacterium mortiferum

Preincubation of lipopolysaccharides (LPS) of Bacteroides fragilis, Bacteroides vulgatus, and Fusobacterium mortiferum with purified human Hageman factor (HF) followed by addition of purified human prekallikrein resulted in the activation of HF, as measured by the generation of kallikrein using the tripeptide substrate N-alpha-benzoyl-L-proline-L-phenylalanine-L-arginine-4-nitroanilide. Addition of purified HF, which had been preincubated with the LPS, to HF-deficient plasma resulted in the acceleration of the recalcification time. Addition of the LPS to HF-deficient plasma reconstituted with various concentrations of HF also resulted in the acceleration of the recalcification time; the magnitude of the acceleration correlated with the amount of HF used to reconstitute the deficient plasma. These results demonstrate that LPS of selected gram-negative anaerobes activate HF and thereby initiate the intrinsic pathway of coagulation.

Enzymes associated with the survival and virulence of gram-negative anaerobes

gram -negative anaerobic bacteria constitute a major portion of the indigenous microflora of humans. Enzymes produced by these bacteria provide nutrients for growth, participate in the pathogenesis of infections involving these bacteria, modify the local environment so that it is suitable for growth, and alter nonnutrients in the immediate vicinity of the bacterial cell. Metabolism of compounds in the gastrointestinal tract by enzymes produced by gram-negative anaerobes may have appreciable effects on the absorption, distribution, and excretion of these compounds as well as on their biologic properties. Knowledge of the enzymes produced by anaerobes is important for understanding and possibly modulating interactions between these bacteria and the host.

Relative roles of burn injury, wound colonization, and wound infection in induction of alterations of complement function in a guinea pig model of burn injury

Stimuli involved in induction of alterations of the complement system and production of circulating inhibitor(s) of phagocytic function of polymorphonuclear neutrophils following burn injury were investigated using a guinea pig model of scald burn injury. The activity of C1-C9, assessed by measurement of total hemolytic complement, was found to increase primarily in response to burn injury per se, whereas reduction in the activity of the alternative complement pathway was shown to develop in association with natural colonization and local burn wound infection with bacterial pathogens. Invasive burn wound infection induced experimentally with Staphylococcus aureus, Pseudomonas aeruginosa, or Candida albicans exacerbated this latter abnormality, caused consumption of C1-C9 activity, and was associated with appearance of serum factors that depressed phagocytosis of Escherichia coli 075 by peritoneal polymorphonuclear neutrophils. Thus injury and coexistent infection both play important roles in induction of humoral alterations of host defense associated with burn injury.

Quantitative variability in requirements for opsonization of strains within the Bacteroides fragilis group

Requirements for opsonization of various strains within the species Bacteroides fragilis, Bacteroides thetaiotaomicron, Bacteroides vulgatus, and Bacteroides distasonis were investigated. The minimal concentration of normal human serum that facilitated maximal uptake by human peripheral leukocytes of 14C-labeled strains ranged from 5% to 80%. Heated (56 C at 30 min) serum produced less uptake than untreated serum, suggesting that complement was required for opsonization. Using human serum depleted of C4 by immunoadsorption as the source of opsonins, predominant utilization of the alternative complement pathway during opsonization was established. Acidic polyanionic exopolymer on the strains was also assessed by ruthenium red staining, electron microscopy, and India ink wet mounts. Strains of the species B thetaiotaomicron, B vulgatus, and B fragilis possessed exopolymer, and a unique configuration of this material was observed on two strains that resisted opsonization. Utilization of classical and/or alternative complement pathway activity during opsonization was not related to the presence of exopolymer.

Staphylococcus in toxic shock syndrome and other surgical infections. Development of new bacteriophages

Recent studies of Staphylococcus aureus isolates from patients with toxic shock syndrome (TSS) have shown the dominance of phage type 29/52 with the capacity to produce pyrogenic exotoxin C and enterotoxin F. They also showed that 29% of the isolates were nontypable and 90% of them had similar toxigenic properties. The existence of unknown and important phages in this disease was postulated. Five new phages were then developed and used for typing three groups of staphylococcal isolates: 236 from patients with TSS, 67 from patients without TSS, and 159 from patients with infected burns. Results showed a high correlation between the lytic action of the new phages and the 29/52 phages, and an additional typing capability in 35% of the previously nontypable TSS isolates, emphasizing further the potential of bacteriophage typing of S aureus in these infections.

Association between microorganism growth at the catheter insertion site and colonization of the catheter in patients receiving total parenteral nutrition

Catheter-related sepsis is one of the major complications of total parenteral nutrition (TPN) therapy. The relationship between microbial colonization of the skin at the site of catheter insertion and colonization of the central venous catheter was investigated in 74 catheters used to administer TPN therapy in 53 patients. Semiquantitative culture specimens were obtained from the insertion site and intravascular and subcutaneous catheter segments at the time of catheter removal. Bacteria and/or fungi were recovered from 19 catheters and 19 insertion sites; of the 19 colonized catheters, 6 had sterile insertion sites. Organisms isolated from the remaining 13 catheters were isolated concurrently from the insertion site. Catheter-associated bacteremia or fungemia was observed in 10 of the 19 patients with colonized catheters. The association between colonization of catheters and the presence of more than 10(3) bacterial or fungal colony-forming units at the insertion site was significant (P less than 0.005). These results demonstrated that colonization of catheters by organisms present on the skin at the site of catheter insertion occurred twice as frequently as colonization by the hematogenous route. The results also suggested that colonization of catheters by organisms present at the insertion site occurred only after a threshold number of organisms was reached.

Staphylococcus aureus associated with toxic shock syndrome: phage typing and toxin capability testing

Phage type 29 Staphylococcus aureus was identified singly or with type 52 in 64.1% of 248 coded isolates from patients with toxic shock syndrome. These phage types also have a high capability of producing pyrogenic exotoxin C and enterotoxin F. The origin and development of these toxigenic strains were explored by studying 25,220 isolates of S. aureus stored in a staphylococcal bank between 1960 and 1979. A small percentage of phage types 29, 52 were found in 1960, but their prevalence increased between 1961 and 1970, and continued at elevated levels through 1979. The toxigenic capabilities of these phage types were apparently acquired about 1971 and increased up to 1975. High levels of prevalence persisted during the following 4 years, and receded in 1980 and 1981. Other evidence during 1980 and 1981 indicates that these strains of S. aureus have become an important pathogen in surgical wounds, burns, and other infections.

Serum-mediated inhibition of polymorphonuclear leukocyte function following burn injury

Serial serum samples from 12 bacteremic burned patients were tested at a physiologic concentration for their ability to facilitate phagocytosis and intracellular killing of the homologous infecting Staphylococcus aureus strains by normal human polymorphonuclear leukocytes in comparison to pooled normal human serum. Serum-mediated inhibition of leukocyte bactericidal activity was demonstrated in three of the patients during 13 to 56 days after burn. Decreased bacterial activity was related to an inhibitory effect of the burn sera on the phagocytic process, which reduced the number of internalized bacteria available for intracellular killing. The serum-mediated inhibition of phagocytosis was not found to be dependent on bacterial surface properties unique to S. aureus. The inhibitory effect was shown to involve a direct interaction of the burn sera with the leukocytes, which was not associated with cell death and was not reversed by washing of the leukocytes.

Studies of the staphylococcal causation of toxic shock syndrome

The data presented in this study indicate that the Staphylococcus aureus is related casually to the toxic shock syndrome and that the dominant phage type was 29. This type has occurred singly as well as in combination with phage type 52 and some other group I phage types. The 29, 52 complex was present in approximately two-thirds of a series of 159 isolates of Staphylococcus aureus obtained from patients with toxic shock syndrome, while another fourth was nontypable. In further support of this concept was the evidence that 94.1 per cent of the isolates of the 29, 52 phage complex tested were capable of producing pyrogenic exotoxin C. These results gave confirmatory evidence of the etiologic importance of this phage type complex of Staphylococcus aureus. The high percentage of 25.8 per cent nontypable isolated has remained unexplained, and this is suggestive of the possibility that another important phage type may be present but obscure, since 83 per cent were shown to be capable of producing pyrogenic C toxin. The data reported also indicated that the current activity of this phage type is another manifestation of the versatility of Staphylococcus aureus and its ability to produce different pathogenic strains capable of causing different or new infections in clinical practice.

Reduction in alternative complement pathway mediated C3 conversion following burn injury

Studies were performed to further investigate an abnormality of the alternative complement pathway associated with burn injury. C3 conversion by inulin and cobra venom factor was measured in serial serum samples from 18 burned patients and in the sera from 25 normal controls. C3 conversion by both activating substances in the patients' sera was significantly decreased during 50 days postburn in comparison to C3 conversion in the normal sera. The most marked reduction in C3 conversion occurred in patients with large full-thickness injuries and infectious complications. However, the abnormality was not more severe in patients with pneumonia and bacteremia in comparison to patients with bacteremia only. It was also not predictive of fatal outcome resulting from infectious complications. Preliminary evidence was presented to suggest that the abnormality is caused by a serum inhibitor, which has an affinity for cellulose and/or is inactivated by it.

Specificity of immunoglobulin M antibodies in normal human serum that participate in opsonophagocytosis and intracellular killing of Bacteroides fragilis and Bacteroides thetaiotaomicron by by human polymorphonuclear leukocytes

Studies were performed to determine the specificity of immunoglobulin M (IgM) antibodies in normal human serum that participate in opsonophagocytosis and intracellular killing of Bacteroides fragilis 1365 and Bacteroides thetaiotaomicron 1343 by human polymorphonuclear leukocytes. Purified normal human IgM was adsorbed with washed heat-killed cells of the homologous strains and heterologous strains of B. fragilis, B. thetaiotaomicron, Bacteroides vulgatus, Bacteroides distasonis, and Bacteroides asaccharolyticus and with erythrocytes coated with outer membrane complex prepared from the homologous strains. Hypogammaglobulinemic serum was supplemented with the adsorbed IgM preparations, and the ability of the supplemented sera to support opsonophagocytosis and killing of B. fragilis 1365 and B. thetaiotaomicron 1343 by human polymorphonuclear leukocytes was measured in vitro under anaerobic conditions. Normal IgM adsorbed with heat-killed cells of B. fragilis 1365 and B. thetaiotaomicron 1343 or with erythrocytes coated with outer membrane complex prepared from these strains failed to restore the ability of hypogammaglobulinemic serum to support opsonophagocytosis and intracellular killing of the homologous strain. In contrast, adsorption of normal IgM with heat-killed cells of the heterologous strains did not alter its opsonophagocytosis-promoting activity for either test strain. These results indicated that the IgM antibodies in normal human serum that participate in opsonophagocytosis and intracellular killing of B. fragilis 1365 and B. thetaiotaomicron 1343 are directed against strain-specific antigenic determinants contained in the outer membrane complex.

Participation of normal human immunoglobulins M, G, and A in opsonophagocytosis and intracellular killing of Bacteroides fragilis and Bacteroides thetaiotaomicron by human polymorphonuclear leukocytes

Restoration of the ability of hypogammaglobulinemic serum to support opsonophagocytosis and intracellular killing of Bacteroides fragilis and Bacteroides thetaiotaomicron by human polymorphonuclear leukocytes was achieved by supplementation with normal human immunoglobulin M, but not with normal human immunoglobulin G. Polymorphonuclear leukocyte bactericidal activity in the presence of immunoglobulin A-deficient human serum was equivalent to that observed in the presence of normal human serum.

Complement, opsonins, and the immune response to bacterial infection in burned patients

Studies were performed to evaluate complement, opsonins, and the immune response to bacterial infection in burned patients. Concentrations and functional acitivities of components of the classical and alternative complement pathways were measured in the sera of four septic, two bacteremic, and four nonseptic burned patients. In addition, heat-labile and heat-stable opsonic activity and agglutinin titers directed against the infecting bacterial strains were measured in the sera of the four septic patients and in an additional group of 11 septic burned patients with abnormal complement profiles. Functional activity of the alternative complement pathway and the concentration of properdin were shown to be persistently decreased during eight weeks postburn in the septic, bacteremic, and nonseptic burned patients; reduced classical pathway activity was demonstrated during the initial postburn period only in the septic patients. Two of the 15 septic patients had decreased heat-labile serum opsonic activity for their infecting bacterial strains, which occurred only during the initial postburn period. Heat-stable opsonins and agglutinin titers in the patients' sera directed against the infecting bacterial strains were equivalent to those in normal human sera, except for the agglutinin titers to Streptococcus faecalis which were increased in the patients' sera in comparison to the normal sera. These results indicate that the multiple complement abnormalities which occur in septic burned patients do not predispose these patients to bacterial infection by decreasing serum opsonic activity. Moreover, heat-stable immune IgG antibodies are not produced during septicemia which facilitate opsonization of the infecting bacterial strains in the absence of an intact complement system.

The septic burned patient: a model for studying the role of complement and immunoglobulins in opsonization of opportunist micro-organisms

Studies were performed to determine the effects of septicemia on complement levels and activities and opsonic function in septic and nonseptic burned patients. None of the nonseptic burned patients had consumption of classical pathway activity during their clinical course. Patients who did not survive septicemia had consumption of all of the classical complement components (C1-C5) prior to and during their septic episodes. Patients who survived septicemia had multiple patterns of classical complement pathway consumption. In these patients, classical pathway activity was restored to normal following the last positive blood culture. Alternative complement pathway consumption was demonstrated in only one of the septic burned patients, as evidenced by decreased factor B and C3b INA levels and decreased C3 and C5 conversion in sera treated with 10 mM ethylene glycol tetraacetic acid and 10 mM MgCl(2) (MgEGTA) and in untreated sera. In all of the other septic patients and in the nonseptic patients, reduction in C3 and C5 conversion in MgEGTA sera and untreated sera was not associated with decrease in factor B or C3b INA. Reduction in complement levels and activities did not reduce the ability of the patients' sera to promote phagocytosis and intracellular killing of their infecting micro-organisms by normal human peripheral polymorphonuclear leukocytes. The results indicate that measurement of classical pathway activity in burned patients can be used as a diagnostic tool for predicting the severity of septic episodes and for monitoring recovery. In addition, the observation that complement consumption did not reduce the opsonic capacity of the patients' sera for their infecting micro-organisms suggests that current concepts regarding the role of immunoglobulins and complement in opsonization of opportunist micro-organisms require re-evaluation.

Participation of immunoglobulin and the alternative complement pathway in opsonization of Bacteroides fragilis and Bacteroides thetaiotaomicron

Studies were conducted to determine the requirements for immunoglobulin and complement in opsonization of Bacteroides fragilis and Bacteroides thetaiotaomicron. The ability of human sera depleted of immunoglobulin or of components of complement to promote the phagocytosis and intracellular killing of the two strains of Bacteroides by human leukocytes was measured in vitro under anaerobic conditions. Neither hypogammaglobulinemic sera nor pooled normal human serum that was heated at 56 C for 30 min supported phagocytosis and killing of the two strains of Bacteroides. Neither sera depleted of terminal complement components by treatment with inulin or cobra venom factor nor human serum deficient in C8 supported phagocytosis of the tested strains. In addition, pooled normal human serum depleted of C3, factor B, or factor D did not support phagocytosis of either strain. Dose-dependent restoration of the opsonic activity of factor B-depleted serum was accomplished by purified human factor B but not by human C2. The results indicate that immunoglobulin and components of the alternative comed in this study.

Participation of immunoglobulin and the alternative complement pathway in opsonization of Bacteroides fragilis and Bacteroides thetaiotaomicron

Studies were conducted to determine the requirements for immunoglobulin and complement for opsonization of Bacteroides fragilis and Bacteroides thetaiotaomicron. The ability of human sera depleted of immunoglobulin or complement components to promote phagocytosis and intracellular killing of the strains of Bacteroides by human leukocytes was measured in vitro under anaerobic conditions. Neither hypogammaglobulinemic sera nor pooled normal human serum (PNHS) heated at 56 C for 30 min supported phagocytosis and killing of the strains of Bacteroides. Sera depleted of terminal complement components by treatment with inulin or cobra venom factor and C8-deficient human serum did not support phagocytosis of the test strains. PNHS depleted of C3, factor B, or factor D also did not support phagocytosis of either strain. Dose-dependent restoration of the opsonic activity of factor B-depleted serum was accomplished by purified human factor B but not by human C2. The results indicated that immunoglobulin and components of the alternative complement pathway participate in opsonization of the strains of Bacteroides tested in this study.

Host defense against opportunist microorganisms following trauma. II. Changes in complement and immunoglobulins in patients with abdominal trauma and in septic patients without trauma

Total hemolytic complement (CH50), conversion of C3 by inulin and cobra venom factor (CoVF), and immunochemical levels of Clq, C4, C2, C3, C5, factor B, properdin, C3b inactivator (KAF), and immunoglobulins (Igs) G, A, and M were measured in the sera of ten patients with abdominal trauma and ten medical patients with septicemia without trauma. Reduction in C3 conversion by CoVF and decrease in the levels of properdin and KAF were demonstrated in the trauma sera. CH50 and the level of C5 were also decreased. Conversion of C3 by inulin and levels of factor B, Clq, C4, C2, and C3 were found to be normal in the patients' sera. Complement levels and activities were found to be normal in the sera of the septic non-trauma patients. A decrease in serum IgM was observed in both patient groups; levels of IgG and IgA were normal. These results indicated that abnormalities of immunoglobulin and of the alternative and classical complement pathways were associated with nonburn trauma. Moreover, the data suggested that consumption of the classical complement pathway associated with septicemia in the thermally injured patient resulted from synergism between the trauma and infection rather than from septicemia per se.

Host defense against opportunist microorganisms following trauma. I. Studies to determine the association between changes in humoral components of host defense and septicemia in burned patients

Total hemolytic complement (CH(50)), conversion of C3 by inulin, and immunochemical levels of Clq, C4, C2, C3, C5, factor B, C3b inactivator (KAF), and properdin were measured in the sera of 15 patients with severe thermal injury during nine weeks postburn. Five of the 15 patients had multiple episodes of septicemia as documented by positive blood cultures and clinical findings. Decrease in CH(50), Clq, C4, C2, C3, and C5 occurred prior to and during septic episodes in these patients. Although conversion of C3 by inulin was often reduced during septic episodes, levels of factor B and KAF were generally normal or elevated. In only one patient did consumption of complement occurring during septicemia decrease the opsonic capacity of the patient's sera for the patient's infecting microorganism, an isolate of E. coli; sera from the same patient opsonized her infecting strain of S. aureus normally. The microorganisms isolated from the other septic patients, which were opsonized normally by the patients' sera despite complement consumption, were also with one exception strains of Staphylococci. In the nonseptic burned patients, decrease in properdin and C3 conversion by inulin, and increase in C3, factor B and KAF were demonstrated as we have previously reported. The results indicate that the classical complement pathway was activated during septicemia in burned patients and that activation of this pathway occurred preferentially due to inhibition of the alternative pathway. In addition, the data show that complement consumption may reduce the opsonic capacity of a patient's sera for certain microorganisms and not for others.

Evaluation of influenza A/New Jersey/76 split-product virus vaccine in a summer camp

An evaluation of two doses of split-product A/New Jersey/76 virus vaccines was conducted at a boys' summer camp. Two doses of either 200 chick cell-agglutinating (CCA) or 400 CCA units of vaccine were administered four weeks apart. There were no significant side effects. Of 60 subjects, 59 developed a significant titer of serum antibody after two doses. There was no correlation between titer of antibody and total dose of vaccine. Younger subjects developed a higher titer than older subjects. A single dose of vaccine was insufficient to achieve a protective level of antibody.

Changes in humoral components of host defense following burn trauma

Serum opsonic activity for E. coli 075, conversion of C3 by inulin, total hemolytic complement (CH(50)), levels of native C3, factor B, C3b inactivator (KAF), properdin (P), and immunoglobulins (Ig) were determined in 14 patients with burns involving 13% to 91% body surface during 6 to 8 weeks postburn. In the 12 uninfected patients, levels of IgG and IgA were reduced during the first 10 days postburn, and decreased concentrations of P and IgM were demonstrated from three to 6 weeks postburn. C3 conversion was reduced from 10 days to 6 weeks postburn. Levels of C3, factor B, and KAF were normal or elevated for the entire study period. No difference in the occurrence of humoral abnormalities was noted in patients with burns caused by flame, immersion scald, or acid contact. Reduction in C3 conversion and P concentration were the only abnormalities which correlated with increasing burn size. Bacteremia and/or fungemia was documented in the other two patients. In one of these patients, reduction in CH(50) occurred during septicemia due to S. aureus, and in the other, reduction in all measurements of complement was associated with candidemia and Pseudomonas septicemia and occurred prior to the development of shock. Serum opsonic activity was only reduced significantly during sepsis, suggesting that this abnormality occurred as a result rather than a cause of infection. These results indicate that consumption of components of the classical and/or alternative pathways of complement activation may be an important mechanism by which infection is perpetuated in the burn patient. They also emphasize the importance of the clinical management of the burn patient in preventing the development of septic complications.

Activation of complement by opportunist pathogens and chemotypes of Salmonella minnesota

Washed cells of Staphylococcus aureus, Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa, and Salmonella minnesota chemotypes (S, Rb, and Re) were tested for their ability to activate the alternative complement pathway (ACP). Parameters of ACP activation were (i) conversion of C3 in 10 mM ethyleneglycol-bis-(beta-aminoethyl ether)-N,N1-tetraacetic acid-treated human serum supplemented with 2.5 mM MgCl2, (ii) lysis of glutathione-treated human erythrocytes in the presence of human serum, and (iii) C3 to C9 consumption in C4-deficient guinea pig serum. With the exception of S. minnesota Re and S. aureus, all of the strains were highly active in the test systems when compared with inulin. S. minnesota Re and S. aureus initiated C3 conversion in untreated human serum, suggesting that these microorganisms were capable of activating complement by a mechanism other than the ACP. These results provide direct evidence for ACP activation by opportunist gram-negative bacilli and refute the hypothesis that the lipid A moiety of the lipopolysaccharide cell wall is responsible for ACP activation.

Reduction in C3 conversion in patients with severe thermal injury

Serum opsonic activity for E. coli 075, concentration of native C3 and C3 conversion by inulin were determined in the sera of five patients with burns involving 45% to 80% total body surface during 3 weeks postburn. In all patients, opsonic activity, C3 concentration, and C3 conversion were reduced during the first week following the injury. C3 was restored to normal or elevated levels by the end of the first week postburn and remained normal or elevated thereafter for the duration of the study. In two patients, opsonic activity and C3 conversion were markedly reduced during the entire 3-week postburn period. In the other three patients, opsonic activity was fully restored to normal within 1 week postburn and, in two of these patients, remained normal thereafter for the duration of the study. In the other patient, opsonic activity became reduced again during the third postburn week. C3 conversion in all five patients remained at a low normal or abnormal level during the entire period of study. Addition of normal human serum to the burn sera fully restored opsonic activity to normal but did not normalize C3 conversion. The results suggest that reduced opsonization is related to a deficiency of serum proteins, whereas reduced C3 conversion may be caused by a circulating inhibitor. Both abnormalities were shown to be associated with microbial infections in burned patients.

Comparison of the in vitro bactericidal activity of human serum and leukocytes against bacteroides fragilis and Fusobacterium mortiferum in aerobic and anaerobic environments

In aerobic and anaerobic in vitro environments, Fusobacterium mortiferum was killed by human leukocytes or serum alone or in combination; clinical isolates of Bacteroides fragilis were killed only by leukocytes in the presence of serum.

Bacteroidaceae in thromboembolic disease: effects of cell wall components on blood coagulation in vivo and in vitro

The effects of Bacteroides sp., Fusobacterium mortiferum, Bacteroides fragilis, and Sphaerophorus necrophorus on various parameters of blood coagulation in vivo and in vitro were determined and compared to the coagulation effects of Escherichia coli and Salmonella minnesota, wild type and R595. Intravenous injection of washed cells, culture filtrate, lipopolysaccharide, or lipid A of the anaerobic gram-negative microorganisms into mice resulted in acceleration of coagulation. Lipopolysaccharide and lipid A of the anaerobic microorganisms had no apparent effect on circulating platelets in mice or rabbits and did not cause aggregation of human platelets in vitro. Washed cells, lipopolysaccharide, and lipid A of Bacteroides sp. and F. mortiferum also significantly accelerated the clotting time of recalcified platelet poor normal human plasma and C6-deficient rabbit plasma. Lipid A, but not lipopolysaccharide, of E. coli and washed cells of S. minnesota R595 accelerated coagulation by a similar mechanism. These results indicated that Bacteroides sp. and F. mortiferum can accelerate blood coagulation in vivo and in vitro by a mechanism which does not involve platelets or terminal components of complement.