Protection from septic shock by neutralization of macrophage migration inhibitory factor.

Identification of new therapeutic targets for the management of septic shock remains imperative as all investigational therapies, including anti-tumor necrosis factor (TNF) and anti-interleukin (IL)-1 agents, have uniformly failed to lower the mortality of critically ill patients with severe sepsis. We report here that macrophage migration inhibitory factor (MIF) is a critical mediator of septic shock. High concentrations of MIF were detected in the peritoneal exudate fluid and in the systemic circulation of mice with bacterial peritonitis. Experiments performed in TNFalpha knockout mice allowed a direct evaluation of the part played by MIF in sepsis in the absence of this pivotal cytokine of inflammation. Anti-MIF antibody protected TNFalpha knockout from lethal peritonitis induced by cecal ligation and puncture (CLP), providing evidence of an intrinsic contribution of MIF to the pathogenesis of sepsis. Anti-MIF antibody also protected normal mice from lethal peritonitis induced by both CLP and Escherichia coli, even when treatment was started up to 8 hours after CLP. Conversely, co-injection of recombinant MIF and E. coli markedly increased the lethality of peritonitis. Finally, high concentrations of MIF were detected in the plasma of patients with severe sepsis or septic shock. These studies define a critical part for MIF in the pathogenesis of septic shock and identify a new target for therapeutic intervention.

Limited CD4+ T-cell renewal in early HIV-1 infection: effect of highly active antiretroviral therapy.

We show that the fraction of proliferating CD4+ lymphocytes is similar in HIV-infected subjects in the early stage of disease and in HIV-negative subjects, whereas the fraction of proliferating CD8+ lymphocytes is increased 6.8-fold in HIV-infected subjects. After initiation of antiviral therapy, there is a late increase in proliferating CD4+ T cells associated with the restoration of CD4+ T-cell counts. These results provide strong support for the idea of limited CD4+ T-cell renewal in the early stage of HIV infection and indicate that after effective suppression of virus replication, the mechanisms of CD4+ T-cell production are still functional in early HIV infection.

Association between protective efficacy of anti-lipopolysaccharide (LPS) antibodies and suppression of LPS-induced tumor necrosis factor alpha and interleukin 6. Comparison of O side chain-specific antibodies with core LPS antibodies.

Two-core LPS antibodies, the rabbit J5 polyclonal antiserum and the human anti-lipid A IgM mAb HA-1A, did not improve the survival of mice challenged with E. coli O111 or P. aeruginosa 3, or with the LPS extracted from them, and did not decrease the incidence of Shwartzman reactions in rabbits challenged with O111 LPS. In contrast, O side chain-specific rabbit antisera were protective in these models. The protection afforded by O side chain-specific antisera against endotoxin lethality was associated with decreased LPS-induced serum TNF and IL-6 levels, whereas core LPS antibodies had no effect on TNF or IL-6 levels. The absence of reduction of LPS-induced cytokines levels by core LPS antibodies suggests that these antibodies are not able to prevent the interactions between LPS and target cells.

Vancomycin prophylaxis of experimental Streptococcus sanguis. Inhibition of bacterial adherence rather than bacterial killing.

Using a strain of Streptococcus sanguis tolerant to vancomycin to infect aortic vegetations in rats, we found that prophylactic intravenous vancomycin given 30 min before bacterial challenge decreased the incidence of endocarditis from 88 to 8% (P less than 10(-5)). Because peak vancomycin serum levels were below the minimal bactericidal concentration, mechanisms of protection other than bacterial killing were investigated. S. sanguis were incubated with inhibitory concentration of vancomycin (50 microgram/ml) for 10 h and washed. 85% of rats (73/86) inoculated with control bacteria developed endocarditis, whereas only 42% (33/78) of those inoculated with vancomycin-exposed bacteria did so (P less than 10(-5)). When rats were killed 30 min after bacterial challenge, S. sanguis were detected by culture of the vegetations in 44% of rats injected with control bacteria, but in only 13% of those challenged with vancomycin-exposed bacteria (P less than 0.03). Enhanced clearance of vancomycin-exposed streptococci was not responsible for this protection because blood cultures showed no difference in the level and duration of bacteremia after injection of control or vancomycin-exposed S. sanguis. Moreover, this protection was not abolished in neutropenic rats injected with vancomycin-exposed bacteria, despite more prolonged bacteremia. These results suggest that vancomycin exerted its protection by lowering adherence of tolerant S. sanguis to vegetations rather than through bactericidal activity or enhanced clearance of bacteria by phagocytic cells. In the choice of antibiotics for prophylaxis of endocarditis, reduction of bacterial adhesion may be a criterion as important as bacterial killing.

Prevention of chronic experimental pyelonephritis by suppression of acute suppuration.

In order to evaluate the importance of suppuration, persistent infection, and scar formation in the evolution of Escherichia coli chronic pyelonephritis, we treated rats with different antibiotic regimens at different stages of the disease. The results show that (a) if acute suppurative pyelonephritis is aborted with early antibiotic therapy, chronic pyelonephritis is prevented; (b) chronic pyelonephritis can develop even after eradication of infection if acute suppuration persists beyond 3 days; (c) persistent infection does not lead to chronic pyelonephritis, if the acute suppuration is suppressed; and (d) residual infection, antigen-load, antibody, and(or) cell-dependent autoimmune processes did not play a significant role. We interpret these results as evidence that the pathologic entity recognized as chronic pyelonephritis results from kidney damage, scarring and shrinkage secondary to acute suppuration.

Piperacillin-tazobactam monotherapy in high-risk febrile and neutropenic cancer patients.

Combination therapy with a beta-lactam plus an aminoglycoside has been the standard approach for treating febrile neutropenia for many years. More recently, beta-lactam monotherapy has also been shown to be a reliable and safe approach. In the present study, 763 eligible patients with fever and neutropenia received piperacillin-tazobactam monotherapy. On day 3, according to the study protocol, 165 patients with persistent fever who fulfilled the study entry criteria were randomised to receive vancomycin or a placebo. The success rate was 51% in the intention-to-treat analysis and 62% in the per-protocol analysis. The overall mortality rate was 8% (58/763), with only 18 (2.4%) deaths attributed to the initial or subsequent infection. Randomisation had no influence on the study endpoints. The adverse event rate was evaluated only in the patient population not included in the randomised part of the study. Among these patients, adverse events probably or definitely related to piperacillin-tazobactam therapy were uncommon, confirming the favourable safety profile of piperacillin-tazobactam. It was concluded that piperacillin-tazobactam could be considered as monotherapy for patients with high-risk febrile neutropenia.

Molecular basis of host-pathogen interaction in septic shock.

Specific mechanisms of recognition of microbial products have been developed by host cells. Among these mechanisms, recognition of lipopolysaccharide of Gram-negative bacteria by CD14, a glycoprotein expressed at the surface of myelomonocytic cells, plays a major role. There is increasing evidence that CD14 also serves as a receptor for other microbial products including peptidoglycan of Gram-positive bacteria. A common theme is that CD14 represents a key molecule in innate immunity. Recognition of microbial products by host cells leads to cell activation and production of a large array of mediators that are necessary for the development of controlled inflammatory processes. When the activation process is out of control, such as in septic shock, these mediators can be detrimental to the host.

Atherogenic dyslipidemia in HIV-infected individuals treated with protease inhibitors. The Swiss HIV Cohort Study.

BACKGROUND: Administration of protease inhibitors (PIs) to HIV-infected individuals has been associated with hyperlipidemia. In this study, we characterized the lipoprotein profile in subjects receiving ritonavir, indinavir, or nelfinavir, alone or in combination with saquinavir. METHODS AND RESULTS: Plasma lipoprotein levels were quantified in 93 HIV-infected adults receiving PIs. Comparison was done with pretreatment values and with 28 nonPI-treated HIV-infected subjects. An elevation in plasma cholesterol levels was observed in all PI-treated groups but was more pronounced for ritonavir (2.0+/-0.3 mmol/L [mean+/-SEM], n=46, versus 0.1+/-0.2 mmol/L in nonPI treated group, P<0.001) than for indinavir (0.8+/-0.2 mmol/L, n=26, P=0.03) or nelfinavir (1.2+/-0.2 mmol/L, n=21, P=0.01). Administration of ritonavir, but not indinavir or nelfinavir, was associated with a marked elevation in plasma triglyceride levels (1.83+/-0.46 mmol/L, P=0.002). Plasma HDL-cholesterol levels remained unchanged. Combination of ritonavir or nelfinavir with saquinavir did not further elevate plasma lipid levels. A 48% increase in plasma levels of lipoprotein(a) was detected in PI-treated subjects with pretreatment Lp(a) values >20 mg/dL. Similar changes in plasma lipid levels were observed in 6 children receiving ritonavir. CONCLUSIONS: Administration of PIs to HIV-infected individuals is associated with a marked, compound-specific dyslipidemia. The risk of pancreatitis and premature atherosclerosis due to PI-associated dyslipidemia remains to be established.

Single daily dose treatment of severe refractory infections with ceftriaxone. Cost savings and possible parenteral outpatient treatment.

Ceftriaxone sodium, a new cephalosporin with a very broad spectrum of action and a very long serum half-life, was administered to 127 patients in the treatment of 133 severe infections at our institution in Lausanne, Switzerland. Eighty infections had previously been treated unsuccessfully with other antimicrobials to which the pathogens were most often resistant. Sixty-five episodes were treated with two daily injections until there was an improvement in the patient's clinical condition, while 67 infections were treated from the start by a single daily injection. The results in the two groups were similar. One hundred fifteen infections (86%) were cured or improved, ten (8%) did not respond to therapy or recurred, and eight (6%) were not evaluable. The treatment was well tolerated, even by the 18 patients who received the drug for more than four weeks. The administration of a single daily dose instead of four doses as with standard antibiotic regimens produced a saving of Sfr 84,000 (+42,000) in the 127 patients. The single daily dose also made it possible to treat 25 of the 127 severely ill patients as outpatients, with a saving of Sfr 388,500 (+195,000) with respect to the hospital costs that would have been incurred for the same time period.

Endocarditis during Staphylococcus aureus septicemia in a population of non-drug addicts.

We examined 76 patients suffering from Staphylococcus aureus septicemia, from 1976 to 1979, none of whom were drug addicts. In contrast to other studies, we found a significant incidence of S aureus endocarditis in patients with a demonstrable portal of entry, a relatively high incidence of metastatic foci in patients without endocarditis, and endocarditis possibly as frequent in patients with hospital-acquired infection as in those with community-acquired infection. These findings suggest caution in determining the length of therapy for S aureus septicemia based on clinical grounds alone.

Cardiobacterium hominis endocarditis manifesting as bacterial meningitis.

Cardiobacterium hominis is a rare cause of endocarditis, and infection caused by this organism has not been described outside the vascular system. A patient with a congenital bicuspid aortic valve was initially seen with C hominis bacterial meningitis. Septic emboli from an underlying endocarditis were probably the source of the infection.

Campylobacter fetus subspecies fetus bacteremia.

Eight patients with Campylobacter fetus bacteremia, six of them with serious underlying diseases, were seen in a two-year period. Besides fever, which was observed in all cases, the most frequent clinical manifestation was lower extremity phlebitis and cellulitis (four patients). In one of these patients, it had the peculiar aspect of bilateral pretibial cellulitis. One patient had vertebral osteomyelitis, a complication, to our knowledge, not yet described. Two patients, both with advanced underlying diseases, died. The five patients who completed a two- to three-week course of erythromycin gluceptate, all had initial clinical improvement. However, one patient suffered a relapse at the end of treatment, and progression of vertebral osteomyelitis while on erythromycin therapy was observed in another patient. These clinical and bacteriologic failures occurred despite the in vitro sensitivity to erythromycin of the two strains. This suggests that erythromycin might not be adequate therapy for C fetus septicemia.

Changes in renal function associated with indinavir.

BACKGROUND: Indinavir use is associated with a spectrum of renal and urinary tract complications including nephrolithiasis, renal colic and pain without recognizable lithiasis, and a picture of crystalluria-dysuria. A frank nephropathy has not been recognized as part of the spectrum. METHODS: A retrospective analysis of 106 HIV-infected individuals receiving indinavir was performed with the purpose of identifying the frequency and risk factors for indinavir-associated nephropathy and urinary complications. Individuals receiving ritonavir or nelfinavir served as controls. RESULTS: A sustained elevation of creatinine (>20%, into abnormal range) was identified in 20 (18.6%) subjects treated with indinavir but not with other protease inhibitors. Creatinine elevation was associated with treatment duration of more than 54 weeks [odds ratio (OR), 7.1; 95% confidence interval (CI), 1.8-27.7], low baseline body mass index < or = 20 kg/m2 (OR, 4.0; 95% CI, 1.0-16.6), and use of trimethoprim-sulphamethoxazole (TMP-SMX; OR, 4.6; 95% CI, 1.5-13.8). Lower urinary specific gravity (P = 0.015), and leukocyturia (P<0.001) were frequently associated features of indinavir nephropathy. No patient developed severe renal impairment and abnormalities were reversible upon discontinuation of the drug. Complications (renal colic, or pain and dysuria) occurred after a mean of 36 weeks (95% CI, 23-48) of indinavir treatment in 13 subjects (12.3%), eight of whom (62%) presented elevated creatinine during follow-up. Only long-term exposure to TMP-SMX (>160 weeks) was identified as a potential risk for the occurrence of a clinical event (OR, 4.7; 95% CI, 1.2-19.2). CONCLUSIONS: A crystal nephropathy, characterized by serum creatinine elevation, loss of concentrating ability of the kidney, leukocyturia, and renal parenchymal image abnormalities, is a frequent complication of indinavir therapy. Identification of individuals at risk, particularly those with low body mass index or receiving TMP-SMX prophylaxis, may help the decision to initiate indinavir or chose an alternative protease inhibitor in order to minimize renal and urinary tract adverse events.

Vancomycin versus placebo for treating persistent fever in patients with neutropenic cancer receiving piperacillin-tazobactam monotherapy.

This prospective, double-blind trial assessed whether the addition of a glycopeptide would be able to reduce the time to defervescence in neutropenic patients with cancer who had persistent fever 48-60 h after the initiation of empirical piperacillin-tazobactam monotherapy. Of 763 eligible patients, 165 with persistent fever were randomized to receive piperacillin-tazobactam therapy plus either vancomycin therapy or placebo. Defervescence was observed in 82 (95%) of 86 patients in the vancomycin group and in 73 (92%) of 79 patients in the placebo group (P=.52). The distributions of the time to defervescence were not statistically significant between the 2 groups (estimated hazard ratio, 1.03; 95% confidence interval, 0.75-1.43; P=.75). The number of additional episodes of gram-positive bacteremia and the percentage of patients for whom amphotericin B was empirically added to their therapy regimen were also similar in both groups. This study failed to demonstrate that the empirical addition of vancomycin therapy to the treatment regimen is of benefit to persistently febrile neutropenic patients with cancer.

Macrophage migration inhibitory factor (MIF) modulates innate immune responses induced by endotoxin and Gram-negative bacteria.

Discovered in the early 1960s as a T-cell cytokine, MIF has emerged to be an important mediator of the innate immune system. MIF was identified recently to be released by a vast array of cells, including monocytes/macrophages, T-cells, B-cells, endocrine cells and epithelial cells in response to infection and stress. Bacteria, microbial toxins and cytokines have been shown to be powerful inducers of MIF secretion by macrophages. MIF stimulates the expression of pro-inflammatory mediators by immune cells and functions to counterbalance the anti-inflammatory and immunosuppressive effects of glucocorticoids. Like TNF and IL-1, MIF plays an important role in host responses to infection. Recombinant MIF was found to exacerbate lethal endotoxemia or bacterial sepsis when co-injected with LPS or Escherichia coli in mice. Conversely, MIF knockout mice or mice treated with anti-MIF antibodies were protected from shock induced by LPS, staphylococcal exotoxins or bacterial peritonitis, even when anti-MIF therapy was started after the onset of infection. Given the central role played by MIF in innate immune responses against microbial pathogens and in the regulation of inflammatory responses, pharmacological modulation of MIF production or neutralization of MIF activity could have broad clinical applications and may offer new treatment options for the management of patients with severe sepsis or septic shock.

Radioimmunoassay versus flow cytometric assay to quantify LPS-binding protein (LBP) concentrations in human plasma.

LPS-binding protein (LBP) is an acute phase protein present in plasma, that has been shown to play a major role in sensitizing monocytes to LPS. We describe here two assays to quantify LBP in plasma. The first assay made use of monophosphoryl lipid A to capture LBP in human plasma, and LBP was detected by radiolabeled anti-LBP IgG. The second assay measured LBP by flow cytometry, using LBPs ability to present LPS to the CD14 receptor present on monocytes. Both assays had a similar level of sensitivity, that allowed the quantification of LBP in human plasma.

Toxicologic and pharmacologic considerations in the choice of empiric parenteral antibiotics.

The last five years have produced an explosive development of new beta-lactam compounds with extended bacterial spectra to include most of the gram-positive cocci as well as the gram-negative bacilli. With the exception of activity against enterococci, there are now third-generation cephalosporins with a spectrum of activity similar to that of the aminoglycosides. In addition, beta-lactams retain a high level of activity against anaerobes and against aerobes surviving in anaerobic conditions, a capacity that is lacking with the aminoglycoside group of antibiotics. The beta-lactams in general and some specific compounds in particular (moxalactam, ceftriazone) have a good penetration into the cerebrospinal fluid, a capacity that is also lacking with the aminoglycosides. Since there is a wide range of different spectra of activity among penicillins and cephalosporins, it is also possible to choose an antibiotic with a spectrum restricted to the offending microorganisms. Finally, because the potential toxicity of beta-lactams is less than that of the aminoglycosides (with the possible exception of myelotoxicity), the first choice of antibiotic in a patient with suspected severe infection should be a beta-lactam. The addition of an aminoglycoside should be reserved for those situations in which a synergistic action between the beta-lactam and the aminoglycoside antibiotics is expected to increase the efficacy of the beta-lactam alone, e.g., enterococcal infections, Pseudomonas aeruginosa infections, infections in severely neutropenic patients, or bacterial endocarditis.

Tolerance study of ceftriaxone compared with amoxicillin in patients with pneumonia.

The safety of ceftriaxone was compared with that of amoxicillin in a randomized study of 91 patients with community-acquired pneumonia. The origin of infection was similar in the two groups. It was proven or probable Streptococcus pneumoniae in 50 percent of the patients and remained uncertain in 40 percent. Ninety percent of the patients who received ceftriaxone were clinically cured compared with 69 percent of those given amoxicillin (p less than 0.05). However, this difference was not apparent among the patients with proven or probable pneumococcal pneumonia. No severe clinical side effects were observed. Cutaneous reactions were more prevalent in the amoxicillin group, whereas mild diarrhea and mucosal candidiasis were more frequent in the ceftriaxone group. Reversible neutropenia was observed in two patients treated with ceftriaxone and none of those treated with amoxicillin.

Immunocompromised animal models for the study of antibiotic combinations.

Studies of various models of Pseudomonas aeruginosa infections in neutropenic animals have demonstrated the superiority of the combination of beta-lactam and aminoglycoside antibiotics when compared with a single drug alone. A limited number of studies carried out in models of Klebsiella pneumoniae infections in neutropenic animals have shown similar results. The efficacy of double beta-lactam combinations for the treatment of gram-negative bacillary infections has not been studied as extensively; the few available reports did not show any benefit over a single beta-lactam treatment. Most studies of combined therapy in gram-positive infections have been performed in the experimental endocarditis model. Experiments in Staphylococcus aureus, Streptococcus viridans, and Streptococcus faecalis endocarditis have shown a clear-cut advantage for combined beta-lactam/aminoglycoside treatment over single beta-lactam therapy, as predicted by in vitro tests. The enhanced efficacy of combined beta-lactam/aminoglycoside treatment in both gram-negative bacillary and gram-positive coccal infections appears to result in most studies in increased and faster killing of the bacteria. With P. aeruginosa infections, however, experiments in neutropenic mice suggest that in addition to increased killing, the beta-lactam arm of the combined treatment prevents the emergence of the small colony variants that lead to treatment failures during therapy with aminoglycoside alone. For both gram-negative bacillary and gram-positive coccal infections, in vitro tests that demonstrated synergism for the combined antibiotics generally predicted enhanced therapeutic efficacy in vivo. Conversely, when no synergism was demonstrated in vitro, there was generally no increased efficacy of combined treatment in vivo. Animal models add a dimension to our understanding of the efficacy of antibiotics, both singly and in combination, that is not always apparent from the results of in vitro tests alone. These in vivo tests can be of value when planning clinical trials.

Do monoclonal antibodies and anticytokines still have a future in infectious diseases?

The continuing high mortality of septic shock has prompted a major effort by the research community to identify novel therapeutic targets. These targets can be conveniently grouped into (1) those derived from microbial components or products; (2) inflammatory mediators; and (3) effector molecules. Many of the experimental, so-called adjunctive agents developed have been monoclonal antibodies or anticytokine molecules of various kinds, and some have progressed into clinical trial. Unfortunately, these trials have failed to show unequivocal survival benefit for patients in shock, prompting a reappraisal of our approach to these agents. In this article, we discuss the possible reasons for these failures: (1) the targets are wrong; (2) the agents are inappropriate; or (3) the trial design is flawed. It would be premature to conclude that adjunctive agents have no future in the therapy of sepsis, but identifying the correct agent, and perhaps more importantly, the correct target population, is going to be more difficult than was at first believed.