[Amebic liver abscesses with bacterial superinfection in a nonendemic area]

A 26-year-old man was admitted to hospital with asthenia, weight loss, right upper quadrant abdominal pain, diarrhea without blood, and fever. Abdominal ultrasonography showed multiple hypoechoic areas in the left hepatic lobe. On abdominal CT, multiple hypodense areas without contrast capture were consistent with hepatic abscesses. Cultures were obtained and the patient was placed empirically on metronidazole, gentamicin and ampicillin, without improvement in the first 72 hours, and a drain was placed in the largest lesion collecting a purulent material. The abscess culture was positive for group C beta-hemolytic Streptococcus. Entamoeba histolytica serology was positive and colon biopsies revealed trophozoites. Multiple left hepatic lobe abscesses secondary to E. histolytica, with bacterial superinfection, is an unusual presentation of amoebic infection, considering that Spain is not an endemic area.

Targeted prevention for people with HIV/AIDS: feasible and desirable?

People with HIV/AIDS are rarely chosen as a target group for prevention activities. In this paper we look at empirical and theoretical evidence for the feasibility and desirability of directing preventive interventions at HIV-positives. Research data on the behaviour and motivation of HIV-positives suggests that the differences between HIV-positives and HIV-negatives and those who are unaware of their HIV-status are not large. However, specific determinants of behaviour, such as responsibility for others or the risk of superinfection, have seldom been measured. Effective interventions targeting at HIV-positives and focussing on prevention are lacking. Fear of increased stigmatization has been used as an argument against focussing prevention activities at HIV-positives. Theoretically that argument is probably not correct: positive coping with HIV may invite positive reactions. The conclusion is that HIV-positives should be chosen as a special target group for additional planned preventive interventions. Because people need to be aware of their HIV status, testing and treatment sites are adequate settings. Effective interventions should be developed on the basis of theory and evidence about the specific determinants of risk behaviour of HIV-positives: protecting oneself for superinfection and protecting one's partner.

Viral superinfection in previously unrecognized chronic carriers of hepatitis B virus with superimposed acute fulminant versus nonfulminant hepatitis

The role of viral superinfection in hepatitis B surface antigen carriers with superimposed fulminant (n = 60) versus nonfulminant (n = 90) acute hepatitis was studied. The frequency of hepatitis A virus (HAV) (0 versus 2.2%), HCV (18.3 versus 21.1%), HDV (15.0 versus 7.8%), and HEV (1.7 versus 4.4%) infection showed no significant difference, while simultaneous HCV and HDV infection was significantly more prevalent in the former (8.3 versus 0%). Only 3. 6% of fulminant cases and 3.3% of nonfulminant controls were HGV RNA positive.

[Fatal course of measles infection in a patient with a low-grade malignant non-Hodgkin lymphoma]

HISTORY AND CLINICAL FINDINGS

A 35-year-old man, for 6 years known to have non-Hodgkin lymphoma (NHL) was admitted because of deteriorating general condition, drowsiness and 11 days of flu-like symptoms. A generalized rash had been noted 5 days after onset of symptoms. His 2-year-old son had fallen ill with measles a few days earlier. The patient had reportedly had measles as a child. On admission a generalized rash was found, he had a fever of 40.5 degrees C, tachypnoea, conjunctivitis and possible meningismus.

INVESTIGATIONS

Lactate dehydrogenase activity was raised to 458 U/ml, and C-reactive protein to 240 mg/ml. Cerebrospinal fluid contained 8/3 cells and protein of 269 mg/l. The chest radiogram revealed opacification in the left upper lobe. Computed tomography of the skull demonstrated a pansinusitis.

DIAGNOSIS, TREATMENT AND COURSE

As measles encephalitis seemed unlikely he was treated for the measles superinfection of bacterial pneumonitis (measles RNA in the bronchoalveolar lavage) and the sinusitis with broad-spectrum antibiotics. After initial improvement artificial ventilation had to be be gun on day 3 because of an acute respiratory distress syndrome, diagnosed both clinically and radiologically. Despite additional antiviral and intensive medical treatment he died on day 11.

CONCLUSION

Patients with impaired immunocompetence due to NHL may lose their immunological "memory" for a previous measles infection. Prevention of exposure may therefore be necessary, in addition to early hyperimmunoglobulin administration.

Risk of hepatitis A superinfection in patients with underlying liver disease

During recent years the outcome of acute hepatitis A in chronic liver disease has been discussed controversially. Data from large hepatitis A epidemics and surveillance data from the United States suggest a significantly higher risk of fatal outcome in patients with chronic hepatitis B. Patients with chronic active hepatitis or liver cirrhosis seem to be at highest risk, while HBsAg carriers may exhibit a benign course of the disease. Patients with chronic hepatitis C also seem to have a significantly higher risk of fulminant hepatic failure when superinfected with hepatitis A. The recently reported unsuspected coincidence of autoimmune markers with a fulminant course of hepatitis A in those patients needs to be confirmed. Vaccination against hepatitis A in patients with chronic liver disease has been shown to be safe and effective.

Clostridium septicum infection and hemolytic uremic syndrome

Five cases of Clostridium septicum infection secondary to Escherichia coli O157-induced hemolytic uremic syndrome have been reported. We report on three cases (one of which is included in the above five) of dual Cl. septicum and E. coil infection; all three patients were exposed to farm animals. A common zoonotic source for Cl. septicum and E. coli O157 infections should be considered. Patients with hemolytic uremic syndrome should be treated aggressively and monitored closely for Cl. septicum superinfection.

The effect of superinfection on the distribution of the infectious period--a continued fraction approximation

It has been shown that the density function of the duration of infection in a superinfection malaria model can be approximated by a mixture of exponential density functions. This is achieved by an application of continued fractions. Numerical calculations and graphs illustrate that this approach is effective.

Lethal synergism between influenza infection and staphylococcal enterotoxin B in mice

Superantigen hyperactivation of the immune system has variable, sometimes lethal consequences for the host. Here we show that concurrent influenza infection enhanced the effects of the bacterial superantigen staphylococcal enterotoxin B (SEB) in mice. The effect was T cell-dependent, and maximal synergism was observed when SEB was administered 7 days after the virus, a timepoint during infection associated with high viral titers, a vigorous cytotoxic T cell response, and extensive lung pathology. The influenza infection enhanced the SEB-induced cytokine response in terms of higher absolute levels of cytokine, sustained secretion, and localization to the respiratory tract. In particular, TNF and IFN-gamma were implicated in the mechanism of death because their neutralization protected the mice from death, and recombinant IFN-gamma and TNFalpha mimicked the lethal effect of SEB in influenza-infected mice. This lethal synergism between concurrent influenza infection and superantigen exposure points to the danger of secondary bacterial involvement in viral pneumonia, and suggests mechanisms that may contribute to sudden and unexpected death from influenza infection. In addition, these data demonstrate that the in vivo effects of superantigen exposure can be strongly influenced by the immune activation status of the host.

Results of a randomized trial of granulocyte colony-stimulating factor in patients with infection and severe granulocytopenia

A study was carried out to investigate the efficacy and toxicity of granulocyte colony-stimulating factor (G-CSF) in the treatment of infection in 119 severely granulocytopenic patients with hematological malignancies after intensive chemotherapy. Patients were assigned randomly to receive either antibiotics alone (ceftazidime, 2 g, i.v., every 8 h + amikacin 7.5 mg/kg, i.v., every 12 h) or the same antimicrobial regimen plus G-CSF (5 micrograms/kg/day, s.c.). Measurements were clinical improvement, eradication of infection and toxicity. Patients who received antibiotics plus G-CSF had more clinical responses (82 versus 60%), less superinfections (6 versus 20%), less mortality (5 versus 15 patients), less days in hospital (median 10 versus 27) and reduced antibiotic usage compared to patients who received only antibiotics. Hematological recovery (granulocytes > 1.0 x 10(9)/l) was also shorter in these patients (12 versus 23 days). Fungal infections occurred only in the group treated with antibiotics alone. Toxicity secondary to G-CSF was absent. We conclude that the addition of G-CSF to broad spectrum antibiotics is useful in selected patients with severe granulocyctopenia after intensive chemotherapy and infection, because if may prove the outcome in these patients.

Acute hematogenous osteomyelitis of a closed fracture with chronic superinfection

Acute hematogenous salmonella osteomyelitis is rare among immunocompetent adults. In this study, the authors reported an unusual case of salmonella enteriditis osteomyelitis of the humerus complicated by methicillin-resistant Staphylococcus aureus superinfection and eventual chronic osteomyelitis in an immunocompetent host. Resection of the humeral head and a significant portion of the humeral shaft coupled with numerous surgical debridements and intravenously administered antibiotics led to resolution of symptoms. This case provides a rare example of acute hematogenous osteomyelitis complicating a closed fracture and demonstrates the difficulty associated with eradication of these specific organisms while emphasizing the principle of aggressive surgical debridement in cases of chronic osteomyelitis.

Randomized comparison between antibiotics alone and antibiotics plus granulocyte-macrophage colony-stimulating factor (Escherichia coli-derived in cancer patients with fever and neutropenia

PURPOSE

A prospective, randomized study was conducted to determine if recombinant human granulocyte-macrophage colony-stimulating factor (rh-GMCSF) (Escherichia coli-derived) could improve response rates to antibiotic therapy and shorten the duration of neutropenia in cancer patients.

PATIENTS AND METHODS

A total of 107 febrile neutropenic cancer patients were randomly assigned to empiric therapy with ticarcillin-clavulanate (4 g ticarcillin + 0.1 g clavulanate i.v. every 4 hours) plus netilmicin (2 mg/kg i.v. every 8 hours) with or without rh-GMCSF (3 micrograms/kg per day i.v.). Clinical improvement, duration of neutropenia, and toxicity were monitored.

RESULTS

Addition of rh-GMCSF to the antibiotics significantly improved the response rate (96% versus 82%, P = 0.03), but not the survival rate (93% versus 93%), in the evaluable patients. This difference in response rate was not significant when considering all patients in an intent-to-treat analysis. The number of patients who recovered from severe neutropenia ( < 100 cells/microliter) during the period of observation in the study was significantly greater among patients receiving the colony-stimulating factor, although the median duration of neutropenia was not affected. Superinfections and subsequent infections were not significantly different among the two treatment regimens. Side effects were more common among patients treated with the colony-stimulating factor.

CONCLUSIONS

Our data do not support the routine administration of rh-GMCSF with antibiotics for patients with fever and neutropenia. Further studies should be conducted to identify those patients most likely to benefit from rh-GMCSF therapy, such as patients with persistent profound neutropenia and refractory infections.

Acute exacerbation and superinfection in patients with chronic viral hepatitis

Recent studies, particularly those in Orientals, have shown that both acute exacerbation from the reactivation of the original virus and acute superinfection with other viruses occur frequently in patients with chronic viral hepatitis. The clinicopathologic features of acute exacerbation and acute superinfection are similar to those of acute hepatitis caused by a single virus, but acute exacerbation is usually less severe than acute superinfection. Recurrent acute exacerbations result from the host's intermittent but persistant efforts to eliminate the replicating virus by immune-mediated mechanisms, thus killing hepatocytes with viral replication. Severe acute exacerbation or acute superinfection may result in immediate hepatic decompensation, or even mortality, and late disease progression, including liver cirrhosis and hepatocellular carcinoma. Further studies are needed to elucidate the basic mechanisms and provide more effective ways to avoid acute exacerbation and acute superinfection in patients with chronic viral hepatitis.

A large randomized clinical trial of a silver-impregnated urinary catheter: lack of efficacy and staphylococcal superinfection

PURPOSE

The antibacterial activity of silver-containing compounds has recently been employed in constructing medical devices, such as vascular and urinary catheters, that may be effective in blocking infection. The present study was designed to evaluate the efficacy of a silver oxide-coated urinary catheter.

PATIENTS AND METHODS

A total of 1,309 hospitalized patients who required placement of an indwelling urinary catheter for 24 hours or longer were randomly assigned to receive either a silicone catheter coated externally with 5% silver oxide or a standard silicone elastomer-coated latex catheter. Daily catheter-urine specimens were collected aseptically and catheter-care violations were monitored daily for the duration of the catheterization.

RESULTS

Bacteriuria developed in 85 of 745 patients (11.4%) in the silver-coated catheter group and in 73 of 564 patients (12.9%) in the control group (P = 0.45). In women who did not receive antibiotics, the rates were 29.3% and 30.4%, respectively (P = 0.98). In men who did not receive antibiotics, the rate of bacteriuria was significantly higher with the silver-coated catheter (29.4% compared to 8.3%, respectively, P = 0.02). Staphylococcal species were isolated more often from the silver-coated catheter group than from the control group (25% versus 8% of all isolates, respectively, P = 0.002).

CONCLUSIONS

This study, the largest ever reported evaluating any silver-impregnated device, has not only failed to demonstrate the efficacy of silver in prevention of catheter-associated bacteriuria, as suggested in prior studies, but it has also shown a significantly increased incidence of bacteriuria in male patients and a significantly increased occurrence of staphylococcal bacteriuria. These results suggest the need for caution and for similar large-scale trials before silver-containing compounds are widely used for preventing device-associated infections, both in vascular and urinary catheters.

Viral potentiation of bacterial superinfection of the respiratory tract

Virus infections of the respiratory tract predispose it to bacterial superinfections. Epidemiological studies, clinical evidence of viral-bacterial co-infection and animal models of such interactions suggest a time course of events and several mechanisms by which viral potentiation may occur. It appears that structural and functional disruption of the respiratory mucosal epithelium is a major contributor to the synergistic effects of superinfection.

Osteomyelitis due to Bacillus cereus in an adolescent: case report and review

Non-anthracis Bacillus species associated with clinical infections are usually dismissed as contaminants or nonpathogens. As opportunists, however, Bacillus organisms can cause significant systemic infections including bacteremia, endophthalmitis, and pneumonia. Osteomyelitis with non-anthracis Bacillus organisms has been described in adults, although to our knowledge it has been described only once in a child. We report a case of chronic osteomyelitis due to Staphylococcus aureus and superinfection with Bacillus cereus in a 13-year-old adolescent. A Bacillus isolate should be considered a true pathogen in children with chronic osteomyelitis who have a poor clinical response to antistaphylococcal therapy.

Ceftazidime compared with piperacillin and tobramycin for the empiric treatment of fever in neutropenic patients with cancer. A multicenter randomized trial. The Intercontinental Antimicrobial Study Group

OBJECTIVE

To compare piperacillin and tobramycin with ceftazidime alone for the empiric treatment of fever in the neutropenic patient without evidence of skin infections or anaerobic infections.

DESIGN

A multicenter, randomized, controlled trial.

PATIENTS

876 febrile, neutropenic episodes in 696 patients (83% acute leukemia or bone marrow transplantation); 92 episodes were excluded from analysis because of protocol violation.

INTERVENTIONS

Patients received either intravenous ceftazidime (2 g every 8 h) or piperacillin (12 to 18 g/d in 4 to 6 divided doses plus tobramycin (1.7 to 2.0 mg/kg body weight every 8 h). Treatment could be modified at any time at the discretion of the investigator.

MEASUREMENTS

Percentage of satisfactory response, eradication of the infecting organism, development of superinfections, and occurrence of adverse events.

RESULTS

As a single agent, ceftazidime was as effective as the combination of piperacillin and tobramycin (62.7% satisfactory responses compared with 61.1%; odds ratio, 1.07%; 95% Cl, 0.79 to 1.44; P > 0.2). Equivalent responses were also obtained in episodes of profound neutropenia (odds ratio, 0.76; Cl, 0.43 to 1.33; P > 0.2). Infectious mortality was 6% for ceftazidime and 8% for the combination therapy. Eradication of the infecting organisms was achieved in 79% of bacteremic episodes treated with ceftazidime compared with 68% of the episodes treated with the combination therapy (odds ratio, 1.76; Cl, 0.92 to 3.38; P = 0.08), and rates for gram-negative rod bacteremia were also similar (95% compared with 77%; odds ratio, 5.25; Cl, 1.0 to 27.5; P = 0.03). Superinfections developed in 38 episodes in each group. An adverse event occurred in 8% of episodes treated with ceftazidime compared with 20% of episodes treated with combination therapy (P < 0.001).

CONCLUSION

Ceftazidime alone was as effective but safer than the combination of piperacillin and tobramycin for the empiric treatment of febrile, neutropenic patients, even those with profound and prolonged granulocytopenia.

[Imipenem-cilastatin in the treatment of suppurative inflammatory complications in the cancer clinic]

The results of the treatment with imipenem/cylastatin (Merck, Sharp and Dohme) of 46 oncological patients whose condition was severe or extremely severe because of infectious complications are presented. The drug was administered intravenously drop-like in doses of 1.5 or 2 g a day. The paper also presents the data on the in vitro susceptibility of 492 strains of aerobic organisms causing purulent inflammatory and septic complications. The majority of the strains were susceptible to imipenem/cylastatin (80-100 per cent depending on the genus and species). A complete or partial therapeutic effect was observed in 30 out of 46 patients. The adverse reactions in several cases required the use of some other drug. Still, they were not life-threatening. Therefore, imipenem/cylastatin should be considered to be a highly efficient combination with antibacterial action. It is useful in the treatment of severe purulent inflammatory complications in oncological patients.

Granulocyte-macrophage colony-stimulating factor in combination with pentavalent antimony for the treatment of visceral Leishmaniasis

The efficacy of GM-CSF was investigated in 20 neutropenic patients (< 1500 neutrophils/microliters) with acute visceral leishmaniasis due to Leishmania chagasi. Patients were randomized to receive either GM-CSF, 5 micrograms/kg daily (intravenously or subcutaneously), or placebo for ten days, in combination with pentavalent antimony, 10-20 mg/kg daily for 20 days. Neutrophil counts were significantly greater on days 5 and 10 of treatment in the GM-CSF group compared with the placebo group (p < 0.02). Eosinophil and monocyte counts were also significantly increased in the GM-CSF group at day 10 (p < or = 0.03). Interestingly, at day 30, platelet counts were significantly increased in the GM-CSF group on days 5 and 10 (p = 0.04 and 0.02, respectively). Patients in the GM-CSF group experienced fewer secondary bacterial or viral infections than placebo patients. Infections occurred in only three patients given GM-CSF compared with eight patients given placebo (p < 0.04). All patients had complete resolution of disease symptoms at three months. Few adverse events were recorded. GM-CSF given subcutaneously at a dose of 5 micrograms/kg daily for ten days was well tolerated, reversed neutropenia rapidly and reduced the number of secondary infections in patients with leishmaniasis.

Persistent infection with Ehrlichia chaffeensis

Although persistent infection of animals by members of the genus Ehrlichia is well known and may be associated with subsequent severe or fatal illness, persistent infection of humans with Ehrlichia chaffeensis has not been reported. Herein we report a typical case of serologically documented acute ehrlichiosis; despite therapy with tetracycline and chloramphenicol, the patient's condition progressively worsened and he suffered multiple secondary infections and gastrointestinal hemorrhage. He died 68 days after his initial hospitalization. Retrospective immunohistologic examination of both acute-phase bone marrow specimens (obtained day 12 of illness) and postmortem liver tissue specimens (obtained day 68 after onset of disease) revealed E. chaffeensis morulae in mononuclear cells, presumably macrophages and monocytes. Findings of this case provide the first definitive evidence that E. chaffeensis is capable of establishing persistent human infection and suggest a role for this obligate intracellular bacterium in the induction of immune compromise associated with a fatal outcome.