Comparison of total antibody and interferon-γ T-cell responses in patients following infection with brucellosis in Georgia

Brucellosis is an ancient disease that still remains a significant threat to humans and is typically linked to exposure to infected animals and/or consumption of unpasteurized animal products. Despite this history, we have a relatively limited understanding of the host characteristics of this disease; consequently, further research is necessary. In this study, we examined the humoral immune response in 43 Georgian individuals that had been diagnosed with brucellosis 3-12 months before enrollment in the study, many of whom still had symptoms after the completion of antibiotic therapy. In total, 35 of 43 (83%) of the patients had antibodies that bound to Brucella lipopolysaccharide (LPS) by COMPELISA, and 34 of 38 (89%) patients had demonstrable specific antibodies to Brucellergene™ antigens; the results from the two ELISAs were highly correlated (p=0.031, r=0.851). We also studied the cellular immune responses in 15 patients. All of the patients generated interferon (IFN)-γ in response to ex vivo stimulation with Brucella protein antigens, and the majority of the patients maintained measurable humoral responses to both LPS and protein antigens. From this initial study, we conclude that measurement of antibody and of cellular (IFN-γ) responses to brucellergene OCB protein epitopes may be worthy of further investigation as an alternative or adjunct to current diagnostics.

Successful use of feedback to improve antibiotic prescribing and reduce Clostridium difficile infection: a controlled interrupted time series

OBJECTIVES

To investigate the effect of reinforcing a narrow-spectrum antibiotic policy on antibiotic prescription and Clostridium difficile infection (CDI) rates by feedback of antibiotic use to doctors, as part of a departmental audit and feedback programme.

DESIGN

A prospective controlled interrupted time-series (ITS) study, with pre-defined pre- and post-intervention periods, each of 21 months.

SETTING

Three acute medical wards for elderly people in a teaching hospital.

PARTICIPANTS

Six thousand one hundred and twenty-nine consecutive unselected acute medical admissions aged >or=80 years.

INTERVENTIONS

A 'narrow-spectrum' antibiotic policy (reinforced by an established programme of audit and feedback of antibiotic usage and CDI rates) was introduced, following an unplanned rise in amoxicillin/clavulanate (Augmentin) use. It targeted broad-spectrum antibiotics for reduction (cephalosporins and amoxicillin/clavulanate) and narrow-spectrum antibiotics for increase (benzyl penicillin, amoxicillin and trimethoprim). Changes in the use of targeted antibiotics (intervention group) were compared with those of untargeted antibiotics (control group) using segmented regression analysis. Changes in CDI rates were examined by the Poisson regression model. Methicillin-resistant Staphylococcus aureus (MRSA) acquisition rates acted as an additional control.

RESULTS

There was a reduction in the use of all targeted broad-spectrum antibiotics and an increase in all targeted narrow-spectrum antibiotics, statistically significant for sudden change and/or linear trend. All other antibiotic use remained unchanged. CDI rates fell with incidence rate ratios of 0.35 (0.17, 0.73) (P=0.009). MRSA incidence did not change [0.79 (0.49, 1.28); P=0.32].

CONCLUSIONS

This is the first controlled prospective ITS study to use feedback to reinforce antibiotic policy and reduce CDI. Multicentre ITS or cluster randomized trials of this and other methods need to be undertaken to establish the most effective means of optimizing antibiotic use and reducing CDI.

Treatment of murine pneumonic Francisella tularensis infection with gatifloxacin, moxifloxacin or ciprofloxacin

The efficacies of gatifloxacin and moxifloxacin were assessed in a BALB/c mouse model of pneumonic tularemia and compared with the efficacy of ciprofloxacin. The rate of relapse following dexamethasone treatment was also investigated. Mice were given 100 mg/kg of the antibiotic by oral administration twice daily for 14 days following an aerosol challenge. All three fluoroquinolones prevented disease during the treatment period, but significant failure rates occurred after the cessation of therapy. Both gatifloxacin and moxifloxacin were more effective than ciprofloxacin at reducing late mortality. Fluoroquinolones may therefore be considered useful candidates for the treatment of pneumonic tularemia.

Comparison of gatifloxacin, moxifloxacin and ciprofloxacin for treatment of experimental Burkholderia pseudomallei infection

OBJECTIVES

To compare the efficacy of moxifloxacin, gatifloxacin and ciprofloxacin for the post-exposure prophylaxis and treatment of experimental Burkholderia pseudomallei infection. The presence of persistent infection in treated animals and the rate of relapse following dexamethasone treatment were also investigated.

METHODS

BALB/c mice were inoculated subcutaneously with 1.75 x 10(6) cfu of B. pseudomallei strain 576. Gatifloxacin, moxifloxacin and ciprofloxacin (100 mg/kg) were given orally at 12 hourly intervals for 14 days starting at 6 h, 7 days or 12 days post-challenge. Control mice did not receive antibiotic therapy.

RESULTS

No regimen gave 100% protection. Prophylaxis was most effective when started 6 h post-challenge, with survival rates at 42 days for ciprofloxacin, gatifloxacin and moxifloxacin being 58%, 75% and 75%, respectively. For treatment started at day 7 post-challenge, survival rates were 17%, 11% and 44%, respectively. When antibiotic treatment was delayed until day 12 post-challenge, survival rates fell to 21%, 17% and 28%, respectively. Following dexamethasone treatment of survivors at 42 days post-challenge, relapses occurred in all treatment groups.

CONCLUSIONS

Fluoroquinolones do not provide good post-exposure protection against infection with B. pseudomallei. The newer agents moxifloxacin and gatifloxacin are not significantly better than ciprofloxacin for this purpose.

Post-exposure prophylaxis of systemic anthrax in mice and treatment with fluoroquinolones

OBJECTIVES

To compare the fluoroquinolones gatifloxacin and moxifloxacin with ciprofloxacin for post-exposure prophylaxis of systemic anthrax in a BALB/c mouse model.

METHODS

Treated mice and controls were inoculated subcutaneously with 5 x 10(4) spores/mouse of Bacillus anthracis Ames strain and observed for 37 days after challenge. Treated mice were given 100 mg/kg of antibiotic orally twice daily for 14 days, starting at various times post-challenge.

RESULTS

Treatment starting 6 h post-challenge resulted in survival rates of 90%, 15% and 40% for gatifloxacin, moxifloxacin and ciprofloxacin, respectively. Treatment commencing 24 h post-challenge resulted in survival rates of 65%, 10% and 5%, respectively. Treatment starting more than 24 h after exposure had little effect on survival.

CONCLUSIONS

Gatifloxacin appeared to be more effective than moxifloxacin or ciprofloxacin, at similar doses, for early post-exposure treatment of murine systemic anthrax. However, these results might be due to differences in potency or pharmacokinetic properties.