Cost-effective aminoglycoside therapy in surgical patients

Community-acquired bacteria frequently detected by means of quantitative polymerase chain reaction in nosocomial early-onset ventilator-associated pneumonia*

OBJECTIVE

To test whether real-time polymerase chain reaction allows for rapid quantitative detection of Streptococcus pneumoniae, Chlamydia pneumoniae, Mycoplasma pneumoniae, and Legionella pneumophila in bronchoalveolar lavage fluids and to determine the prevalence of these pathogens in nosocomial ventilator-associated pneumonia.

DESIGN

Prospective epidemiologic study applying a new molecular biology-based diagnostic tool during a 27-month period.

SETTING

Three medical intensive care units of a tertiary care university hospital.

PATIENTS

One hundred patients suffering from nosocomial ventilator-associated pneumonia, hospitalized for > or =14 days, intubated for reasons other than pneumonia, and mechanically ventilated for >48 hrs.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

S. pneumoniae, M. pneumoniae, and C. pneumoniae were detected in bronchoalveolar lavage fluids of 100 patients in 20 (20%), three (3%), and two (2%) cases, respectively. There of 17 (71%) revealed no growth or no significant growth by conventional culture. In one patient, S. pneumoniae and M. pneumoniae were detected simultaneously. Corresponding colony-forming units/mL were partly up to 10 CFU/mL with Gram stainings showing signs of acute inflammation in 80%. A significant temporary correlation between the number of days on ventilator, development of nosocomial pneumonia, and the frequency of detection of these pathogens was found for day 4.

CONCLUSIONS

S. pneumoniae, M. pneumoniae, and C. pneumoniae should be considered as causative agents in critically ill patients who develop early-onset nosocomial ventilator-associated pneumonia. Thus, empirical antimicrobial regimens should cover S. pneumoniae, Chlamydia, and Mycoplasma alike. Quantitative polymerase chain reaction is a fast diagnostic tool allowing for detection of these bacteria within 3 hrs in pretreated patients.

Retrospective analysis of the clinical and economic outcomes of twice-daily dosing of cefotaxime in a Canadian tertiary care institution

A retrospective analysis of the clinical and economic outcome of a regimen of cefotaxime 1 g given every 12 h was conducted following the introduction of an institutional policy recommending this new dosing strategy. Patients were identified from a log order entry in the pharmacy, and the medical records were reviewed using a standardized data collection form. Explicit criteria were applied for the indications for antimicrobial therapy, presence of infection, and outcome parameters. A total of 60 patients with a mean (+/- SD) age of 56.2 (+/- 17.8) years and a mean (+/- SD) length of stay of 20.75 (+/- 18.1) days were identified. Of these, 48 (80%) were found to have a clinically or microbiologically documented infection, and of the 42 patients who could be assessed accordingly to the criteria chosen, 37 (88%) had a favorable clinical response; 21 patients (35%) received cefotaxime alone. The costs for administration of cefotaxime have decreased by approximately 30% since the introduction of this new dosing regimen.

The antibiotic cost calculator; an expert system for global antibiotic cost calculation

An application to cost antibiotic therapy was developed using Object Vision, an object-oriented software development program. The application facilitates calculation of the cost of up to six antibiotics (three oral and three intravenous) in terms of acquisition, delivery, laboratory and complication components. The application consists of two files. The first file allows entry of basic cost data. The second file allows the user to define each antibiotic regimen and the management, and thus the cost, of complications relevant to the antibiotics being costed; costs are automatically calculated and displayed. The program also contains a help system; this comprises extensive explanation of each stage of the calculation process, a summary of recent literature on the percentage incidence of complications for commonly used antibiotics, and a bibliography. The summary and bibliography may be printed. The program is designed for use by hospitals, universities and pharmaceutical companies for calculation of total in-patient charges, marketing and research. It is a user-friendly system which dramatically reduces the inherent complexities of this area of medicine.

Circadian variation in amikacin clearance and its effects on efficacy and toxicity in mice with and without immunosuppression

A once-daily dosage regimen has been recently recommended in the use of aminoglycoside antibiotics since they induce a postantibiotic effect. In choosing this regimen, one must determine the most appropriate time of day for administration of the drug. We investigated the effects of the timing of amikacin (AMK) administration on the kinetics, the efficacy against intraperitoneal infection with Pseudomonas aeruginosa, and the toxicity of AMK in mice with and without immunosuppression. We found circadian variations in the kinetics, efficacy, and toxicity of the drug in mice. Male and female ICR mice, which were housed under a light-dark (12:12 h) cycle with free food and water intake, were injected subcutaneously with AMK sulfate 50 mg/kg body wt. There was a circadian variation in AMK clearance for both sexes with the maximum value in the dark phase and the minimum in the light phase after a single administration. When AMK 500 mg/kg/day was repeatedly administered once daily for 30 days, higher toxicity was demonstrated in mice injected with the drug at the time of day with lower AMK clearance, although no difference was demonstrated in the toxicity between the two time points with different AMK clearance when AMK 1,500 mg/kg was administered in a single dose. The ED50 of AMK to cure the infected mice in the midlight phase (13:00 h) with lower clearance was significantly lower than that in the middark phase (01:00 h) with higher clearance. In contrast, the ED50 in the early light phase (09:00 h) was significantly lower than that in the early dark phase (21:00 h), although AMK clearance was no different between these two different time points. In mice premedicated with cyclophosphamide to suppress immune functions, the difference in the ED50 of AMK was still demonstrated between 13:00 and 01:00 h, but not between 09:00 and 21:00 h. The present study shows not only that there were circadian variations in both AMK clearance and toxicity after repeated administration, but also that there was a circadian variation in the efficacy of AMK in mice infected with P. aeruginosa. These results suggest that the timing of drug administration should be considered in pharmacotherapy with AMK and that the most appropriate time of administration in mice and nocturnal animals may be in the midlight (resting) phase. They also suggest that the ED50 of AMK against P. aeruginosa infection may be influenced not only by the circadian variation in pharmacokinetics but also by the variations in immune systems suppressed by cyclophosphamide.

Evaluation of clinical judgment in the identification and treatment of nosocomial pneumonia in ventilated patients

To evaluate the accuracy of clinical judgment in the diagnosis and treatment of nosocomial pneumonia in ventilated patients, we studied 84 patients suspected of having nosocomial pneumonia because of the presence of a new pulmonary infiltrate and purulent tracheal secretions. We prospectively evaluated the accuracy of diagnostic predictions and therapeutic plans independently formulated by a team of physicians aware of all clinical, radiologic and laboratory data, including the results of Gram-stained bronchial aspirates. Definite (n = 51) or probable (n = 33) diagnoses could be established in all patients by strict histopathologic and/or bacteriologic criteria. Only 27/84 patients were diagnosed as having pneumonia. Organisms responsible for pneumonias were identified by quantitative cultures of samples obtained using a protected specimen brush or pleural fluid cultures. Four hundred eight predictions were made for the 84 studied patients. Clinical diagnoses for patients subsequently diagnosed as having pneumonia were accurate in 81/131 cases (62 percent). Furthermore, only 43/131 (33 percent) therapeutic plans proposed for these patients represented effective therapy. Common causes of inappropriate treatment included failure to diagnose pneumonia (50 plans), failure to effectively treat highly resistant organisms (21 plans), and failure to treat all organisms in cases of polymicrobial pneumonia (14 plans). Therapeutic plans formulated for patients without pneumonia included the unnecessary use of antibiotics in 45/277 cases (16 percent). These findings indicate that the use of clinical criteria alone does not permit the accurate diagnosis of nosocomial pneumonia in ventilated patients, and commonly results in inappropriate or inadequate antibiotic therapy for these patients.

Evaluating the cost-effectiveness of treatment with third-generation cephalosporins

Spreadsheet computer software was used to compare the estimated global treatment costs of the third-generation cephalosporins, cefotaxime and ceftriaxone, in the management of pneumonia using treatment schedules taken from current studies. Included in the analysis were not only acquisition costs, but also costs that contribute to total expenses for a course of treatment, such as those of (a) preparation and administration (disposable supplies, nursing, and pharmacy time), (b) projected laboratory costs to monitor for hypoprothrombinemia, and (c) complication costs (diarrhea, superinfection, pseudocholelithiasis, and so on). The cost analysis was performed using United States trial-derived factors. Where published cost factors were not available, reasonable estimates were sought. Our analysis indicates that cefotaxime therapy may be less costly than ceftriaxone therapy in the dosage schedules used in these clinical studies and routine clinical practice.

Aminoglycoside therapy. Current use and future prospects

The microbiological, pharmacokinetic, toxicological and clinical aspects of aminoglycosides are reviewed. Aminoglycosides still have an important place in serious infections in neutropenic patients, endocarditis and Pseudomonas aeruginosa infections, all in combination with beta-lactams. Monotherapy (with streptomycin) is indicated in less common diseases like tularemia and bubonic plague. Several experimental studies support a once-daily dosing regimen for aminoglycosides (comparable or better efficacy with less ototoxicity and nephrotoxicity). Only a very limited number of prospective comparative studies have been performed, and much more data on efficacy, development of resistance and toxicity is needed before once-daily administration can be recommended. The choice of an aminoglycoside should be based primarily on the local sensitivity patterns and cost. Differences in ototoxicity and nephrotoxicity are usually minor. If the acquisition costs of amikacin decline, it is to be expected that amikacin will be the aminoglycoside of choice.

Aminoglycosides: current role in antimicrobial therapy

Aminoglycosides remain the cornerstone of antibiotic therapy for nosocomial, gram-negative bacillary infections despite the recent introduction of broad-spectrum beta-lactam antibiotics and quinolones with antipseudomonal activity. Initially, aminoglycosides were used as antiaerobic gram-negative antimicrobial therapy. Currently, they have a key role in many types of infections, such as gram-negative urosepsis and in febrile granulocytopenic patients, because of their established antipseudomonal activity. Empiric treatment of febrile episodes in granulocytopenic cancer patients with an aminoglycoside, in combination with an anti-pseudomonal beta-lactam, accounts for much of the aminoglycoside use. Amikacin is emerging as one of the most effective aminoglycosides on the basis of resistance rates, pharmacokinetic factors likely to affect clinical efficacy, safety, and overall cost of therapy.

Physician-generated cost containment in transurethral prostatectomy

Cost containment need not be imposed on physicians by government, insurance companies and hospital administrators. Decreases in hospital cost can be achieved voluntarily by physicians without sacrificing quality of care, especially for common procedures with relatively homogeneous patient populations, such as transurethral prostatectomy. Variations in existing practice were identified and shared, and optimal scientific practice was discussed at 5 meetings of the division of urology during a 16-month period. Strict guidelines were not developed; surgeons were encouraged to apply cost-related knowledge individually. Resource use was measured before, during and after the intervention. A total of 356 transurethral prostatectomies was studied. There were significant decreases in preoperative and postoperative length of stay, specific ordering practices and total hospital charges. University faculty differed from community urologists and individual surgeons varied considerably. Suggestions for scientific cost management in prostatectomy are presented.