The aim of the study was to assess the microbiological activity and clinical efficacy of colistin and rifampin combination against multidrug-resistant (MDR) Pseudomonas aeruginosa infections. The antimicrobial activity of the colistin/rifampin combination was evaluated using the checkerboard and time-kill curve methods against different MDR P. aeruginosa strains. The combination of rifampin and colistin resulted fully (1 strain) or partially (5 strains) synergistic for 6/7 strains and minimum inhibitory concentrations (MICs) in combination were reduced to easily obtainable therapeutic levels. The time-kill curves showed that the combination was bactericidal against the strains tested. The clinical efficacy of the combination was tested in four patients with difficult-to treat infections (sepsis or pneumonia) caused by MDR P. aeruginosa. All infections were successfully treated. Our microbiological and clinical observations suggest that the addition of rifampin to colistin may result in a synergistic bactericidal combination that may be useful in patients with infections caused by MDR P. aeruginosa which are difficult to cure.

SUMMARYThe exerdse-electrocardiography test shows limited feasibility and diagnostic accuracy for the ooninvaslve detection of coronary artery disease hi hypertensive patients. Recently, the dipyridamoleechocardiography test (two-dimensional echocardtographic monitoring with dipyridamole infusion, up to 0.84 mg/kg over 10 minutes) has been proposed as an exercise-independent method for the diagnosis of coronary artery disease. The diagnostic usefulness of the exerdse-electrocardiography test and the dipyridamole-echocardiography test was evaluated in 63 consecutive inpatients with history of chest pain, essential hypertension, and no previous myocardial infarction. The criterion of posltlvity for the exerdse-electrocardiography test was a horizontal or downsioping ST segment shift exceeding 0.1 mV and for the dipyridamole-echocardiography test, a transient dyssynergy of contraction. Fifteen patients could not perform a diagnostic exerdse-electrocardiography test because of an nubility to exercise adequately (two patients), severe hypertension hi spite of full antihypertensive therapy (six patients), or excessive blood pressure rise at the first step of the exercise-electrocardiography test (seven patients). Five patients could not perform the dipyridamole-echocardiography test because of a poor acoustic window. The overall feasibility was 76% for the exercise-electrocardiography test and 92% for the dipyridamoleechocardiography test (p < 0.05). All 43 patients who performed both tests underwent coronary angiography; 30 had significant coronary artery disease (>70% lumen reduction of at least 1 major coronary vessel). Sensitivity was 67% for both the exercise-electrocardiography test and the dipyridamoleechocardiography test (p = NS); spedfidty was 46% for the exerdse-electrocardiography test and 92% for the dipyridamole-echocardiography test {p < 0.05). Thus, the dipyridamole-echocardiography test represents a good diagnostic alternative to the exercise-electrocardiography test hi symptomatic hypertensive patients, as it has a similar sensitivity and higher feasibility and spedfidty for the detection of coronary artery disease.

Dobutamine-atropine and dipyridamole-atropine stress echocardiography are safe and feasible, although submaximal studies are more frequent with dobutamine. The two stresses have comparable accuracy in the detection of angiographically assessed coronary artery disease, although dobutamine is marginally more sensitive and dipyridamole marginally more specific. Stratification of the ischemic response in the space domain is also comparable with the two stresses.

We retrospectively evaluated the safety and effectiveness of colistin alone or in combination with other antimicrobials in eight diabetic patients with severe diabetic foot infections due to multidrug resistant (MDR) Pseudomonas aeruginosa, complicated in 4 cases by osteomyelitis. All patients received colistin after other ineffective antimicrobial treatment, when MDR P. aeruginosa strains were isolated by cultural examination and together with a multidisciplinary care approach including revascularization, surgical debridement and adequate offloading. The mean duration of therapy was 72 +/- 52.9 days. Six out of 8 patients (75%) successfully benefited from colistin therapy, while 2 patients failed and/or experienced side effects that led to discontinuation of therapy. Serious adverse events (i.e. acute renal failure and pulmonary edema) were observed in 1 patient. Our data allow us to conclude that colistin, alone or in combination with other antimicrobials, is safe and effective when administered as part of a multidisciplinary approach, to promote healing of diabetic foot infection due to MDR P. aeruginosa.