Impact of empiric weight-based vancomycin dosing on nephrotoxicity and mortality in geriatric patients with methicillin-resistant Staphylococcus aureus bacteraemia

WHAT IS KNOWN AND OBJECTIVE

Few studies have evaluated the effect of vancomycin dosing on the health outcomes in geriatric patients. Data are needed to determine whether higher vancomycin dosing strategies are more effective in geriatric patients and/or lead to excessive rates of adverse events.

METHODS

This study used a subset of patients aged ≥65 years from a multicentre, retrospective, cohort study of methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia. Patients received ≥ 48 h of empiric vancomycin between 1 July 2002 and 30 June 2008. We compared the incidence of nephrotoxicity and in-hospital mortality in patients who received guideline-recommended dosing (at least 15 mg/kg/dose) to patients who received lower dosing. Multivariable generalized mixed-effect models were constructed to determine independent risk factors for nephrotoxicity and in-hospital mortality.

RESULTS AND DISCUSSION

Half of the cohort (46% of 92 patients) received guideline-recommended dosing. Empiric use of weight-based dosing did increase the percentage of patients achieving a vancomycin trough ≥ 15 mg/L (57% vs. 42%). Nephrotoxicity occurred in 32% of patients and 26% died during their hospitalization. Guideline-recommended dosing was not associated with significant changes in nephrotoxicity (OR 1·13; 95% CI 0·40-3·19) or in-hospital mortality (OR 1·14; 95% CI 0·41-3·18) in the multivariable analysis.

WHAT IS NEW AND CONCLUSION

In this study of geriatric patients, guideline-recommended dosing was not associated with significant changes in nephrotoxicity or mortality. As 40% of the patients who received guideline-recommended dosing failed to achieve a target vancomycin trough of ≥ 15 mg/L, future studies should focus on dosing strategies to increase target attainment rate.

Use of quinupristin/dalfopristin in a critical patient with a methicillin-resistant Staphilococcus aureus infection

The growing incidence of infections due to Gram-positive multiresistant germs has stimulated research into new drugs endowed with broader activity, that are useful in case of infections unresponsive to common antibiotics. The case of a 28-year-old man infected with a methicillin resistant Staphylococcus aureus non responder to therapy with glycopeptide antibiotics is reported. At admission the patient presented a septic condition and required mechanical ventilation. Antibiotic therapy was immediately started with teicoplanin+meropenem. Blood culture and bronchial aspirate evidenced a methicillin resistant Staphylococcus aureus with high sensibility to glycopeptide antibiotics. Although this therapy produced a slight improvement in clinical condition and the patient was extubated, fever and leucocytosis associated with a BAL positive to methicillin resistant Staphylococcus aureus, in vitro susceptible to glycopeptides, persisted. Considering the possibility of a non-responder condition of the patient to glycopeptide antibiotics, quinupristin/dalfopristin was added. The streptogramin produced a quick improvement in clinical condition with resolution of sepsis and culture sterilization. The patient improved progressively and was discharged. In conclusion, in our experience the association quinupristin/dalfopristin was effective in the resolution of a critical methicillin resistant Staphylococcus aureus infection non responder to classical treatment with glycopeptide antibiotics that showed a high sensibility in vitro.

Bluetongue surveillance in the Campania Region of Italy using a geographic information system to create risk maps

The aim of the project was the implementation of a geographic information system (GIS) to study areas of the Campania Region that are potentially at risk for bluetongue (BT) infection. As a first step, environmental, meteorological and climatic features were surveyed to evaluate areas where Culicoides could be present. A risk map was developed and five zones with different risk levels were defined. Data from Culicoides trapping were surveyed to evaluate the capability of the risk map to predict presence/absence of vectors. Finally, data from 2002 BT surveillance (outbreaks and serologically positive sentinels [SPS]) were compared to the map. Captures of Culicoides, SPS and BT in areas the map indicated as a medium/high risk level, seem to confirm reliability of the produced map. However, very few C. imicola were captured in these medium/high risk areas.