A case series of macrolide treatment failures in community acquired pneumonia

This was a retrospective, multi-center study of patients admitted to hospital with community-acquired pneumonia, caused by Streptococcus pneumoniae, after failing to respond to >2 days of outpatient macrolide therapy. 122 cases, treated between 2000-2004, were enrolled from 31 North American sites between January 2004 - March 2005. Non-susceptible isolates (predominately low-level resistance: erythromycin MICs of 1-16 mcg/ml) were recovered from 87 patients (71%). Bacteremia was present in 63 patients (52%). The in-hospital mortality rate was 5.7 %; all 7 patients who died were bacteremic, 6 had a non-susceptible isolate. We report here the largest series of macrolide failures published to date. The patients were notable for their high rates of macrolide resistance, bacteremia, and mortality. High-level macrolide resistance remains rare among US patients failing outpatient macrolides. The majority of cases and virtually all of the mortality occurred in patients with low-level resistant strains.

Is more than one quinolone needed in clinical practice?

OBJECTIVE

To review clinical information on fluoroquinolone antimicrobials to distinguish between these agents and help define their place in clinical practice.

DATA SOURCES

Primary and review articles on fluoroquinolones available commercially in the US as of August 2000 were identified through MEDLINE (from 1993-August 2000) and secondary sources.

STUDY SELECTION AND DATA EXTRACTION

All pertinent, published, clinical trials for levofloxacin, moxifloxacin, and gatifloxacin were included. Minimal data were included for quinolones with restricted or limited uses, including trovafloxacin, sparfloxacin, enoxacin, and lomefloxacin. Due to the quantity of data on ciprofloxacin, only more recent or pivotal trials or articles summarizing data on specific infections were included. Relevant information was included if it was believed to assist in differentiating between the fluoroquinolones for infections for which these agents would most commonly be considered.

DATA SYNTHESIS

Fluoroquinolones are a potent class of intravenous and oral broad-spectrum antimicrobial agents used for treating a wide range of community-acquired and nosocomial infections. More than 10 quinolones have been approved for use; although some of these have been withdrawn from the market, numerous others are under investigation. It has become increasingly important to be able to differentiate between these agents.

CONCLUSIONS

Differences in safety, antimicrobial spectrum of activity, and resistance development support the selective use of various fluoroquinolones in differing clinical situations.

Cost-effectiveness of Gatifloxacin vs Ceftriaxone With a Macrolide for the Treatment of Community-Acquired Pneumonia

STUDY OBJECTIVE

To determine the cost-effectiveness of sequential IV to oral gatifloxacin therapy vs IV ceftriaxone with or without IV erythromycin to oral clarithromycin therapy to treat community-acquired pneumonia (CAP) patients requiring hospitalization.

PATIENTS

Two hundred eighty-three patients enrolled in a randomized, double-blind, clinical trial were eligible for inclusion in the cost-effectiveness analysis.

METHODS

Data collected included patient demographics, clinical and microbiological outcomes, length of stay (LOS), and antibiotic-related LOS (LOSAR). Costs evaluated include drug acquisition (level 1); plus costs of preparation, dispensing, and administration, treating adverse events, and clinical failures (level 2); plus hospital per diem costs (level 3). Robustness of economic findings was tested using sensitivity analyses.

RESULTS

Two hundred three patients were clinically and economically evaluable (98 receiving gatifloxacin and 105 receiving ceftriaxone). IV erythromycin was administered to 35 patients in the ceftriaxone-treated group. Oral conversion was achieved in 98% of patients in each group. Clinical cure and microbiological eradication rates did not differ statistically (98% and 97% with gatifloxacin vs 92% and 92% with ceftriaxone, respectively). Overall, neither geometric mean LOS nor LOSAR differed significantly (4.2 days and 4.1 days with gatifloxacin vs 4.9 days and 4.9 days with ceftriaxone, respectively). Treatment failures in the ceftriaxone group contributed to a mean incremental increase in LOSAR of 1.09 days and increased mean cost per patient. The geometric mean costs per patient (level 3) were $5,109 for gatifloxacin and $6,164 for ceftriaxone (p = 0.011). The cost-effectiveness ratios (mean cost per expected success) were $5,236:1 and $7,047:1 for gatifloxacin and ceftriaxone, respectively.

CONCLUSIONS

Gatifloxacin monotherapy for CAP patients requiring hospitalization is clinically effective and provides an economic advantage compared to the regimen of ceftriaxone with or without erythromycin IV with a switch to oral clarithromycin.

What have we learned from pharmacokinetic and pharmacodynamic theories?

Pharmacokinetic characteristics and pharmacodynamic properties dictate antimicrobial response and, along with natural immune responses, clinical outcomes. As new agents are developed with long half-lives, we will lose the ability to differentiate between concentration-dependent and time-dependent properties. The area under the inhibitory concentration curve (AUIC) defines drug regimens as a ratio of drug exposure to minimum inhibitory concentration (MIC) and allows them to be compared with each other. With AUIC and agents with long half-lives, these comparisons are possible regardless of chemical classification or concentration or time-dependent activity. Historical examples of reduced drug exposure from decreased doses (i.e., cefaclor, clarithromycin, and ciprofloxacin), and thus low AUIC values, directly correlate with drug resistance. In the face of rising MICs (as is occurring worldwide with Streptococcus pneumoniae), close attention to appropriate dosing and concentration above the MIC may delay and potentially even prevent antibiotic resistance. Creating selective pressure on reliable antibiotics by inappropriately reducing their doses will undoubtedly challenge these agents and may destroy entire drug classes with similar mechanisms of action or resistance.

Economic justification of antimicrobial management programs: implications of antimicrobial resistance

The relationship between the problem of antimicrobial resistance and efforts to control antimicrobial costs is explored. Antimicrobial drug management typically centers around controlling costs and controlling antimicrobial resistance. Selection of therapeutic alternatives without adherence to a well-developed program or without a rationale based on data from the medical literature may promote antimicrobial resistance. Attempts to select alternatives can produce cost shifting rather than cost containment. The annual cost associated with antimicrobial resistance in the United States is estimated to be as high as $47 billion. In one study, patients with bacteremia caused by methicillin-resistant Staphylococcus aureus had an average length of stay 2.7 days longer than patients with susceptible strains and a mean cost of care that was $3500 higher. Infection control is one of the most important duties of health care practitioners. Given today's prevailing reimbursement structure, hospitals with high rates of nosocomial and resistant infections are likely to lose money. A basic problem with the current approach to controlling resistance is that the two most common strategies, highly restrictive formularies and drug cycling, work in opposition. Antimicrobial management programs should be directed at ensuring the most appropriate use of antimicrobials rather than focusing on limiting choices.

Cost effectiveness of cephalosporin monotherapy and aminoglycoside/ureidopenicillin combination therapy. For the treatment of febrile episodes in neutropenic patients

OBJECTIVE

To assess the relative cost effectiveness of cephalosporin monotherapy options and aminoglycoside/ureidopenicillin combination therapy for the treatment of febrile episodes in adult patients with neutropenia.

DESIGN AND SETTING

This was a retrospective cost-effectiveness analysis conducted from the institutional perspective.

METHODS

The analysis was based on 741 febrile episodes in adult patients with neutropenia enrolled in 5 randomised trials: 3 comparing monotherapy with ceftazidime or cefepime, and 2 comparing cefepime monotherapy versus aminoglycoside/ureidopenicillin combination therapy. Resource utilisation included costs for study antibacterials, treatment of adverse effects and failures, and hospitalisation. The primary end-point was the overall cost of treatment per patient. Cost-effectiveness ratios were also analysed.

RESULTS

No significant differences in clinical success rates were detected. Median per-patient costs in the monotherapy comparisons were $US7849 for cefepime and $US7788 for ceftazidime [1997 values; not significantly different (NS)]. Corresponding costs for the monotherapy versus combination therapy comparisons were $US9780 for cefepime and $US10 159 for gentamicin/ureidopenicillin (NS). Despite a higher acquisition cost for cefepime, there were no statistically significant differences in cost effectiveness compared with either ceftazidime monotherapy or gentamicin/ureidopenicillin combination therapy. Sensitivity analyses revealed that monotherapy can be cost effective compared with combination therapy in many situations.

CONCLUSION

There were no economic differences between the 3 regimens tested. Therefore drug cost should not be a deciding factor when choosing antibacterial therapy for the treatment of febrile episodes in adult patients with neutropenia.

Clinical efficacy of intravenous followed by oral azithromycin monotherapy in hospitalized patients with community-acquired pneumonia. The Azithromycin Intravenous Clinical Trials Group

The purpose of this study was to evaluate intravenous (i.v.) azithromycin followed by oral azithromycin as a monotherapeutic regimen for community-acquired pneumonia (CAP). Two trials of i.v. azithromycin used as initial monotherapy in hospitalized CAP patients are summarized. Clinical efficacy is reported from an open-label randomized trial of azithromycin compared to cefuroxime with or without erythromycin. Bacteriologic and clinical efficacy results are also presented from a noncomparative trial of i.v. azithromycin that was designed to give additional clinical experience with a larger number of pathogens. Azithromycin was administered to 414 patients: 202 and 212 in the comparative and noncomparative trials, respectively. The comparator regimen was used as treatment for 201 patients; 105 were treated with cefuroxime alone and 96 were given cefuroxime plus erythromycin. In the comparative trial, clinical outcome data were available for 268 evaluable patients with confirmed CAP at the 10- to 14-day visit, with 106 (77%) of the azithromycin patients cured or improved and 97 (74%) of the comparator patients cured or improved. Mean i.v. treatment duration and mean total treatment duration (i.v. and oral) for the clinically evaluable patients were significantly (P < 0.05) shorter for the azithromycin group (3.6 days for the i.v. group and 8.6 days for the i.v. and oral group) than for the evaluable patients given cefuroxime plus erythromycin (4.0 days for the i.v. group and 10.3 days for the i.v. and oral group). The present comparative study demonstrates that initial therapy with i.v. azithromycin for hospitalized patients with CAP is associated with fewer side effects and is equal in efficacy to a 1993 American Thoracic Society-suggested regimen of cefuroxime plus erythromycin when the erythromycin is deemed necessary by clinicians.

Comparison of the fluoroquinolones based on pharmacokinetic and pharmacodynamic parameters

Assessment of pharmacodynamic activity from standard in vitro minimum inhibitory concentrations (MICs) alone is insufficient to predict in vivo potency. Achievable serum and tissue concentrations as well as pharmacokinetic characteristics must be considered. When pharmacokinetic and pharmacodynamic values are combined, the area under the inhibitory curve (AUIC) and peak concentration:MIC ratio predict clinical cure for fluoroquinolones. Clinical data and animal models indicate that a peak:MIC of 10:1 and above and an AUIC of 125 and above are predictive of a clinical cure for this class of antimicrobials against gram-negative organisms. The values may be used to compare and contrast fluoroquinolones to determine which would be best for treating a specific microorganism. Pharmacodynamic data also can be used to design regimens that minimize the risk of suboptimal drug levels. Ensuring the optimal fluoroquinolone dosage based on pharmacodynamic principles would diminish the emergence of resistant organisms and prevent treatment failures.

Pharmacoeconomics of antimicrobial therapy

Switch therapy, sequential therapy, and step-down therapy are discussed in terms of their contribution to reducing antimicrobial expenditures. Pharmacoeconomics is the science used to identify and compare the costs and consequences of drug therapy in terms of efficacy, safety, and overall health care. Pharmacoeconomic studies of antimicrobials for respiratory-tract infections have identified significant cost savings associated with regimens that are optimized for a particular patient on the basis of a drug's pharmacokinetic profile. For fluoroquinolones, optimal therapy has been associated with targeting the specific pharmacodynamic variable known as the ratio of the area under the serum concentration-time curve from 0 to 24 hours (AUC) to the minimum inhibitory concentration, also referred to as the area under the inhibitory curve (AUIC). Several studies have shown that regimens that achieve targeted AUIC values of 125 to 250 against gram-negative aerobic bacteria are cost-effective; cost savings are linked to decreased time to bacterial eradication and higher AUICs. Additional cost-effective measures for hospitals and health care institutions include the implementation of formalized i.v.-to-oral conversions and streamlining programs. Pharmacoeconomic analysis of therapies for respiratory-tract and other infections demonstrates that reducing health care costs may best be achieved by curing the infection in the shortest possible time through dosage optimization individualized to the patient.

Cost effectiveness of ciprofloxacin plus metronidazole versus imipenem-cilastatin in the treatment of intra-abdominal infections

OBJECTIVE

To compare the cost effectiveness of sequential intravenous (i.v.) to oral ciprofloxacin plus metronidazole (CIP/MTZ i.v./PO) with that of i.v. ciprofloxacin plus i.v. metronidazole (CIP/MTZ i.v.) and i.v. imipenem-cilastatin (IMI i.v.) in patients with intra-abdominal infections.

DESIGN AND PARTICIPANTS

Patients enrolled in a double-blind randomised clinical trial were eligible for inclusion into this cost-effectiveness analysis. Decision analysis was used to characterise the economic outcomes between groups and provide a structure upon which to base the sensitivity analyses. 1996 cost values were used throughout.

SETTING

The economic perspective of the analysis was that of a hospital provider.

MAIN OUTCOME MEASURES AND RESULTS

Among 446 economically evaluable patients, 176 could be switched from i.v. to oral administration. The 51 patients randomised to CIP/MTZ i.v./PO who received active oral therapy had a success rate of 98%, mean duration of therapy of 9.1 days and mean cost of $US7678. There were 125 patients randomized to either CIP/MTZ i.v. or IMI i.v. who received oral placebo while continuing on active i.v. antibacterials; their success rate was 94%, mean duration of therapy was 10.1 days and mean cost was $US8774 (p = 0.029 vs CIP/MTZ i.v./PO). Of the 270 patients who were unable to receive oral administration, 97 received IMI i.v. and had a success rate of 75%, mean duration of therapy of 13.8 days and a mean cost of $US12,418, and 173 received CIP/MTZ i.v. and had a success rate of 77%, mean duration of therapy of 13.4 days and mean cost of $US12,219 (p = 0.26 vs IMI i.v.).

CONCLUSIONS

In patients able to receive oral therapy, sequential i.v. to oral treatment with ciprofloxacin plus metronidazole was cost effective compared with full i.v. courses of ciprofloxacin plus metronidazole or imipenem-cilastatin. In patients unable to receive oral therapy, no difference in mean cost was found between i.v. imipenem-cilastatin or i.v. ciprofloxacin plus i.v. metronidazole.

Influence of fluoroquinolone purchasing patterns on antimicrobial expenditures and Pseudomonas aeruginosa susceptibility

The influence of using ofloxacin in place of ciprofloxacin on hospital fluoroquinolone expenditures, total antimicrobial expenditures, and susceptibility of Pseudomonas aeruginosa to fluoroquinolones was studied. Hospitals with fluoroquinolone expenditures of at least $1 per occupied bed per year were administered annual surveys covering the years 1993 through 1996. The two most recent consecutive years of data were compared among hospitals that used ciprofloxacin as their primary fluoroquinolone during both years (group 1), hospitals whose ofloxacin purchases increased from accounting for < or =25% of total fluoroquinolone expenditures during year 1 to accounting for >25% during year 2 (group 2), and hospitals whose ofloxacin purchases accounted for at least 25% of total fluoroquinolone expenditures for both years (group 3). A total of 109 hospitals were included in the study. Most hospitals spent more on fluoroquinolones and total antimicrobials in year 2 than year 1. Group 3 hospitals had a significant increase in expenditures for fluoroquinolones and non-fluoroquinolone antipseudomonal antimicrobials. Group 2 hospitals did not realize antimicrobial cost savings and had higher rates of Pseudomonas aeruginosa resistance than hospitals that used ciprofloxacin. Whether a hospital changed its pattern of ciprofloxacin and ofloxacin purchasing was not significantly associated with expenditures for fluoroquinolones, nonfluoroquinolone antimicrobial agents, or all antimicrobials. Susceptibility of P. aeruginosa to ciprofloxacin was lower in hospitals with greater proportions of ofloxacin use. Individual hospital, ciprofloxacin expenditures, and study year were found to be predictive of P. aeruginosa susceptibility to ciprofloxacin among all pooled hospitals.

How should we evaluate new anti-infectives for respiratory tract infections?

In assessing the outcomes of anti-infective therapy, microbiological and clinical efficacy have been the most important factors considered. However, increasing attention is being paid to pharmacoeconomic considerations, which include much more than simply the cost of the drug. Nursing and pharmacy time involved in drug preparation and administration, laboratory costs and time in therapeutic drug monitoring, and hospital costs for in-patient care are all factors to be considered. Therapeutic failure caused by using an inexpensive but ineffective drug can thus be very expensive if it leads to prolonged hospitalization. The effort to curb anti-infective drug costs has led to the following strategies: sequential therapy using equipotent oral formulations of intravenous agents; switch therapy, ie, changing to a different class; and step-down therapy, ie, converting to an oral antimicrobial with less potency. Maximal cost effectiveness is related to rapid and effective therapy.

Genesis of methicillin-resistant Staphylococcus aureus (MRSA), how treatment of MRSA infections has selected for vancomycin-resistant Enterococcus faecium, and the importance of antibiotic management and infection control

We extensively studied the epidemiology and time course of endemic methicillin-resistant Staphylococcus aureus (MRSA) in the Millard Fillmore Hospital, a 600-bed teaching hospital in Buffalo. The changeover from methicillin-susceptible S. aureus to MRSA begins on the first hospital day, when patients are given cefazolin as presurgical prophylaxis. Under selective antibiotic pressure, colonizing flora change within 24 to 48 hours. For patients remaining hospitalized, subsequent courses of third-generation cephalosporins further select and amplify the colonizing MRSA population. Therefore, managing antibiotic selective pressure might be essential. Other strategies include attention to dosing, so that serum concentrations of drug exceed the minimum inhibitory concentration, and antibiotic cycling. Although there are some promising new antibiotics on the horizon, it is necessary to deal with many resistance patterns by using the combined strategies of infection control and antibiotic management.

Assessing antibacterial pharmacoeconomics in the intensive care unit

Intensive care units (ICUs) represent areas of high use of antibacterials and other pharmacy goods and services. Many institutions view their ICUs as a target for drug-use surveillance and cost-containment programmes. Economic assessment of antibacterial interventions in the ICU should include all direct costs and patient outcomes. Nonetheless, many of these institutions focus their efforts at reducing antibacterial costs without considering the consequences of these actions. It is possible that devoting more resources to antibacterials can have an overall positive economic impact if more appropriate antibacterial use reduces length of stay, decreases bacterial resistance or lowers frequency of adverse complications. Two consequences of antibacterial use which can result in substantial economic burdens to institutions are drug-induced complications (toxicities and adverse events) and the development of antibacterial-resistant organisms. These events are logical targets for performing pharmacoeconomic studies to evaluate appropriate and inappropriate antibacterial use. Either of these problems can increase length of stay, which is the single most important variable influencing the overall cost of patient care. The primary goal of patient care is to hasten patients' clinical improvement. This will result in decreased antibacterial acquisition costs, decreased lengths of ICU and hospital stays, and ultimately decreased consumption of hospital resources. These can be accomplished by using strategies to guide antibacterial use in order to reduce failures, adverse events, toxicity and antimicrobial resistance.

In nosocomial pneumonia, optimizing antibiotics other than aminoglycosides is a more important determinant of successful clinical outcome, and a better means of avoiding resistance

In in vitro and animal models, antibiotics show good relationships between concentration and response, when response is quantified as the rate of bacterial eradication. The strength of these in vitro relationships promises their utility for dosage regimen design and predictable cure of infections such as nosocomial pneumonia. In spite of their intuitive logic, close relationships between dosage and bacterial eradication have not been easy to show in clinical studies of nosocomial pneumonia. Presumably, a variety of patient, disease, bacterial, and pharmacokinetic variables cloud these relationships in patients, and delay their elucidation in patient trials. Patients with serious infections like nosocomial pneumonia require bactericidal antimicrobial activity. Studies in our laboratory show that the minimum effective antimicrobial action is an area under the inhibitory titer (AUIC) of 125, in which AUIC is calculated as the 24 hour serum area under the curve (AUC) divided by the minimum inhibitory concentration (MIC) of the pathogen. This target AUIC may be achieved with either a single antibiotic or it can be the sum of AUIC values of two or more antibiotics. There is considerable variability in the actual AUIC value for patients when antibiotics are administered in their usual recommended dosages. Examples of this variance will be provided using aminoglycosides, fluoroquinolones, and beta-lactams. The achievement of minimally effective antibiotic action, consisting of an AUIC of at least 125, is associated with bacterial eradication in about 7 days for beta-lactams and quinolones. Adding an aminoglycoside to beta-lactams may produce a slight increase in their rate of bacterial killing in vivo, but because of their narrow therapeutic window, and the associated low doses in relation to MIC, there are situations in which the aminoglycosides may be unable to add sufficient additional AUIC. Antibiotic activity indices allow clinicians to evaluate individualized patient regimens. Furthermore, antibiotic activity is a predictable clinical endpoint with predictable clinical outcome. This value also is highly predictive of the development of bacterial resistance. Antimicrobial regimens that do not achieve an AUIC of at least 125 cannot prevent the selective pressure that leads to overgrowth of resistant bacterial subpopulations. The methods based on the determination of AUIC have clinical applicability in routine practice, through software developed for this purpose. These indices can assist with patient management strategies in a prospective manner because they can identify patients at high risk of therapeutic failure or acquired resistance early in therapy before therapy fails. Our studies show that calculations of AUIC can be used to prospectively target regimens to improve the chances of cure with nosocomial pneumonia and other serious infections. A clinical intervention team has been organized to optimize antimicrobial regimens as early in therapy as possible, to lower the high cost events such as failure and acquired bacterial resistance.

Cost-effectiveness comparison of sequential ofloxacin versus standard switch therapy

OBJECTIVE

To compare the cost-effectiveness of sequential intravenous-to-oral ofloxacin versus intravenous-to-oral standard switch therapy for the treatment of patients with sepsis who are hospitalized with bacterial infections.

DESIGN

Cost-effectiveness analysis from a provider perspective, including resources important to an integrated healthcare network, of a randomized, open-label, controlled, clinical trial.

SETTING

Millard Fillmore Health System, Buffalo, NY.

PATIENTS

Hospitalized adults requiring parenteral antibiotics for a complicated urinary tract infection, lower respiratory tract infection, or skin and soft tissue infection.

INTERVENTIONS

Sequential intravenous-to-oral ofloxacin or standard intravenous-to-oral switch antibiotics.

OUTCOME MEASURES

Clinical outcomes and direct costs associated with hospitalization, primary physician services, specialist physician services, and outpatient care.

RESULTS

Eighty-two of 89 patients randomized into the two treatment groups were evaluable. Standard switch therapy failed with 12 patients versus 10 patients receiving ofloxacin. Complete economic data were available for 74 patients. Sequential ofloxacin therapy resulted in a 1-day-shorter antibiotic-related hospitalization without evidence of recurrent infection during the posttherapy follow-up evaluations. An average cost savings of $399 per patient was achieved in the sequential ofloxacin group. Although this difference did not attain statistical significance (probably due to the large variance), it is an economically significant finding. The cost-effectiveness ratios were $5735 per successful outcome for the standard switch therapy group versus $5126 per successful outcome in the sequential ofloxacin group.

CONCLUSIONS

Sequential ofloxacin was as effective and consistently less expensive than standard switch antibiotics in the initial evaluation and in the sensitivity analysis of room cost and drug acquisition cost. Standard switch therapy would have to be greater than 25% more effective than sequential ofloxacin therapy to change the economic decision.

Changing the infection control paradigm from off-line to real time: the experience at Millard Fillmore Health System

In 1993, several departments at Millard Fillmore Health System joined efforts to initiate a new approach to infection control. The main emphasis of this program is to move infection control to a real-time mode to manage patient outcomes daily. The principal objective was to decrease the number of nosocomial infections by 10%, with a particular emphasis on surgical-site infections. Besides real-time surveillance, we are critically evaluating several aspects of the management of nosocomial infections. High-level computer support has been the frame-work upon which this program was built. We have microcomputers that are linked directly to microbiology, pharmacy, billing, and admissions, downloading data several times daily. An expert software system merges all of the data, and from this we can target patients for real-time interventions. The computer system allows all inpatients to be screened for either infection control or antibiotic management interventions on a daily basis, with minimal time being spent on data collection and maximal efforts devoted to interventions at the bedside. Additionally, the infection management program will assist in maintaining the extraordinarily low expenditures on antimicrobial agents. During 1993, the Millard Fillmore Health System spent $924,884 on antibiotics, an amount approximately 50% that of comparably sized hospitals.

Cost-effectiveness of ampicillin/sulbactam versus imipenem/cilastatin in the treatment of limb-threatening foot infections in diabetic patients

A cost-effectiveness analysis was performed following a double-blind, randomized study of ampicillin/sulbactam (A/S) versus imipenem/cilastatin (I/C) for the treatment of limb-threatening foot infections in 90 diabetic patients. There were no significant differences between the treatments in terms of clinical success rate, adverse-event frequency, duration of study antibiotic treatment, or length of hospitalization. Costs of the study antibiotics, treatment of failures and adverse events, and hospitalization were calculated. Mean per-patient treatment cost in the A/S group was $14,084, compared with $17,008 in the I/C group (P = .05), primarily because of lower drug and hospitalization costs and less-severe adverse events in the A/S group. Sensitivity analyses varying drug prices or hospital costs demonstrated that A/S was consistently more cost-effective than I/C. Varying the clinical success rate for each drug revealed that I/C would have to be 30% more effective than A/S to change the economic decisions.

Cost-effectiveness of abbreviating the duration of intravenous antibacterial therapy with oral fluoroquinolones

Comprehensive economic analyses should include outpatient as well as inpatient resources. A healthcare system that includes both inpatient and outpatient care, such as prescriptions, physician care, laboratory tests and multiple other items, has been termed an Integrated Healthcare Network (IHN). Thus, cost-effectiveness analyses from the perspective of an IHN are necessary. We report a cost-effectiveness analysis from an IHN perspective on 187 evaluable hospitalised patients with serious infection who participated in randomised clinical trials that evaluated either: (i) standard regimens of intravenous (i.v.) antibacterial therapy, usually followed by oral antibacterial therapy; or (ii) an abbreviated regimen of intravenous antibacterials for 2 to 4 days, followed by either oral ciprofloxacin or oral enoxacin as early switch therapy. Clinical success rates were similar for the 2 treatment groups. The median number of days of in-hospital antibacterial treatment was 11 for standard i.v. therapy and 10 for switch therapy. Adverse events occurred in 33% of the standard i.v. therapy group and in 50% of the switch therapy group. Sensitivity analysis of drug price and hospital bed cost showed that switch therapy was consistently more cost effective than standard i.v. therapy. Standard i.v. therapy would have to be 10% more effective than switch therapy to change the economic decision. In this analysis, switch therapy was a cost-effective treatment with no demonstrated change in efficacy compared with standard i.v. therapy.

The economic potential of dual individualisation methodologies

Cost-effective treatment of patients with bacterial infections can best be accomplished by facilitating a rapid response. Achieving a more rapid cure of the infection should result in reduced utilisation of healthcare resources. An innovative means of achieving a more rapid response to antibacterial therapy has been termed dual individualisation. Dual individualisation allows for the simultaneous consideration of the pharmacokinetic interaction between an antibacterial agent and a patient, with the pharmacodynamic interaction between the antibacterial agent and the bacterial pathogen. Integrating the pharmacokinetic parameter of area under the curve (AUC), with the pharmacodynamic measure of minimum inhibitory concentration (MIC) yields a ratio called the area under the inhibitory curve (AUIC). Clinical studies using dual individualisation to achieve a target AUIC24h of 125-250 have been performed with cephalosporins and fluoroquinalones. Economic evaluation of the results demonstrate that dual individualisation is cost-effective. Dual individualisation can be implemented in most practice setting using existing clinical data. Use of a computer model allows for cost-effective calculation of AUIC24h without having to measure serum drug concentrations of bacterial MIC. By adjusting antibacterial regimens to achieve a target AUIC, optimisation of antibacterial therapy can be achieved with resultant economic benefits.

Cefepime: a fourth-generation parenteral cephalosporin

OBJECTIVE

To review the chemistry, microbiology, pharmacokinetics, therapeutic efficacy, adverse effect profile, drug interactions, dosing, and administration of cefepime, a new fourth-generation parenteral cephalosporin.

DATA SOURCES

A MEDLINE search of the available literature, including clinical trials and reviews, was performed. Abstracts presented at recent scientific conferences and current publications were also reviewed.

DATA SELECTION

In vitro and preclinical data were included, as well as data from Phase II and III clinical trials.

DATA SYNTHESIS

Cefepime is an extended-spectrum parenteral cephalosporin antibiotic active in vitro against a broad spectrum of gram-positive and gram-negative aerobic bacteria. The gram-positive spectrum is similar to that of cefotaxime, the gram-negative spectrum is similar to that of ceftazidime, and many, though not all, organisms resistant to these two agents remain susceptible to cefepime, prompting the fourth-generation designation. Cefepime has a high affinity for penicillin-binding proteins and, due to its zwitterionic configuration, rapidly penetrates outer-membrane porin channels of bacteria. Beta-lactamases appear to have a low affinity for the drug. Cefepime has a decreased propensity to induce beta-lactamases compared with other beta-lactam antibiotics. Cefepime has a pharmacokinetic disposition similar to that of other renally eliminated cephalosporins, with a half-life of approximately 2 hours. Cefepime has demonstrated clinical efficacy against a variety of infections, including urinary tract infections, pneumonia, and skin and skin structure infections. Cefepime is generally well tolerated.

Benchmark analysis of strategies hospitals use to control antimicrobial expenditures

Hospital expenditures on antimicrobial drugs, antimicrobial management practices, and the effects of these practices were studied. A survey on institutional budget, size, and staffing; intensive care unit drug costs and use evaluations; and pharmacy expenditures, including antimicrobial costs, for 1993 and 1994 was sent to 122 hospitals. The written survey was followed by telephoned questions regarding each institution's antimicrobial management and expenditures, and any perceived link between the two. Hospitals were grouped by size and type, data were normalized to costs per occupied bed and costs per occupied bed per case mix index, and averages for each size category were calculated for general institutional information and expenses per antimicrobial. Eighty-eight institutions (72%) responded. Although 61% to 74% of the respondents used an antimicrobial formulary to restrict drug choices and control costs, average total antimicrobial expenses increased by more than $300 per occupied bed between 1993 and 1994. Only 7% of the institutions saw decreased costs of $500 or more per occupied bed. The most common reasons for these decreases were restructuring of pricing contracts and implementation of educational programs. The replacement of one formulary alternative with another led to increases in the use of antimicrobials other than the replacement drug and often did not produce savings. The replacement of one formulary antimicrobial with another led more to costshifting than to overall savings.

Survey of ACCP members regarding health economics and outcomes assessment

A letter and a questionnaire were sent to members of the American College of Clinical Pharmacy (ACCP) proposing the formation of a new outcomes and economics practice and research network (PRN). Members were requested to indicate their willingness to join the PRN by returning the questionnaire. More than 10% of the members (327/3007) expressed interest in joining the new PRN; the majority (309) also completed the questionnaire. They were most concerned with increasing their competence in outcomes and economics; developing, or having available, guidelines and standards for research methodologies; properly applying the methodologies to satisfy the informational needs of their institutions; and strengthening and advancing the position of clinical pharmacy.

Pharmacoeconomic comparison of sequential IV/oral ciprofloxacin versus ceftazidime in the treatment of nosocomial pneumonia

A retrospective, cost-effectiveness analysis was performed on 106 clinically evaluable patients who participated in a multi-centre, randomized study of sequential IV/oral ciprofloxacin therapy versus ceftazidime for the treatment of nosocomial pneumonia. Although nearly half of the ciprofloxacin patients received sequential therapy, the majority were treated with a full IV regimen. Clinical success rates and antibiotic-related adverse events were similar for the ciprofloxacin and ceftazidime groups. Per patient and per day costs of antibiotic acquisition; preparation and administration; treatment of adverse events, and clinical failures were compared. Decision analysis revealed that ciprofloxacin therapy was cost-effective compared to ceftazidime 2 g q8h. Varying the probability of clinical success between 60-99% failed to change the economic decision; costs for ciprofloxacin were always lower than for ceftazidime. Further sensitivity analyses demonstrated that if the ceftazidime price was reduced by 50% (equivalent to 1 g q8h), treatment costs would be similar to ciprofloxacin therapy. Increasing the ciprofloxacin price by 50% (equivalent to a q8h frequency) produced per patient costs similar to ceftazidime, although ciprofloxacin therapy retained a lower cost per day (p < 0.0002). For the treatment of nosocomial pneumonia, ciprofloxacin therapy was cost-effective compared to ceftazidime.

Use of benchmarking techniques to justify the evolution of antibiotic management programs in healthcare systems

OBJECTIVE

To apply basic benchmarking techniques to hospital antibiotic expenditures and clinical pharmacy personnel and their duties, to identify cost savings strategies for clinical pharmacy services.

DESIGN

Prospective survey of 18 hospitals ranging in size from 201 to 942 beds. Each was asked to provide antibiotic expenditures, an overview of their clinical pharmacy services, and to describe the duties of clinical pharmacists involved in antibiotic management activities. Specific information was sought on the use of pharmacokinetic dosing services, antibiotic streamlining, and oral switch in each of the hospitals.

RESULTS

Most smaller hospitals (< 300 beds) did not employ clinical pharmacists with the specific duties of antibiotic management or streamlining. At these institutions, antibiotic management services consisted of formulary enforcement and aminoglycoside and/or vancomycin dosing services. The larger hospitals we surveyed employed clinical pharmacists designated as antibiotic management specialists, but their usual activities were aminoglycoside and/or vancomycin dosing services and formulary enforcement. In virtually all hospitals, the yearly expenses for antibiotics exceeded those of Millard Fillmore Hospitals by $2,000-3,000 per occupied bed. In a 500-bed hospital, this difference in expenditures would exceed $1.5 million yearly. Millard Fillmore Health System has similar types of patients, but employs clinical pharmacists to perform streamlining and/or switch functions at days 2-4, when cultures come back from the laboratory.

CONCLUSIONS

The antibiotic streamlining and oral switch duties of clinical pharmacy specialists are associated with the majority of cost savings in hospital antibiotic management programs. The savings are considerable to the extent that most hospitals with 200-300 beds could readily cost-justify a full-time clinical pharmacist to perform these activities on a daily basis. Expenses of the program would be offset entirely by the reduction in the actual pharmacy expenditures on antibiotics.

Ampicillin-sulbactam versus cefoxitin for prophylaxis in high-risk patients undergoing abdominal surgery

This double-blind study compared ampicillin-sulbactam 3 g versus cefoxitin 2 g in 136 adult patients at risk for developing an infection after abdominal surgery. Separate randomization schedules were used for colorectal, upper gastrointestinal/biliary, and other abdominal procedures. Study antibiotics were administered within 30 minutes before incision and repeated 6 hours later. Patients having colorectal surgery received a third dose of antibiotic 6 hours after the second. Efficacy evaluations were made on 123 patients, 62 in the ampicillin-sulbactam group and 61 in the cefoxitin group. The overall postoperative infection rates were 12.9% for ampicillin-sulbactam and 9.8% for cefoxitin (p > 0.05); one wound infection occurred in each group. Adverse events were experienced by 13.2% of the ampicillin-sulbactam and 19.1% of the cefoxitin recipients (p > 0.05). Cost-minimization analysis revealed that ampicillin-sulbactam was a cost-effective alternative to cefoxitin for the prevention of infection after abdominal surgery.

Cost-effectiveness comparison of cefepime and ceftazidime using decision analysis

A retrospective cost-effectiveness analysis, from the institutional perspective, was performed on the 1637 clinically evaluable patients who participated in randomised studies of cefepime versus ceftazidime. The clinical success rate was 88% for patients in both the cefepime and ceftazidime groups. Adverse events occurred in 16.5% of cefepime and 19.0% of ceftazidime patients (p greater than 0.05). In most cases cefepime was administered every 12 hours while ceftazidime was administered every 8 hours. The amount of drug administered per patient (mean+/-SEM) was 17.6+/-0.4g of cefepime and 29.1+/-0.8g of ceftazidime (p less than 0.01). The median number of days of antibiotic treatment was 8 for each group. Decision and sensitivity analyses of drug price and hospital bed cost demonstrated that cefepime was consistently more cost effective than ceftazidime. The probability of clinical success varied between 60 and 97% and revealed that ceftazidime would have to be 31% more effective than cefepime to change the economic decision. If the acquisition prices per gram of drug are similar, cefepime will be cost effective compared with ceftazidime.

Pharmacoeconomic analysis of cefmenoxime dual individualization in the treatment of nosocomial pneumonia

OBJECTIVE

To determine if dual individualization of cefmenoxime dosing is cost-effective.

DESIGN

Retrospective, pharmacoeconomic decision analysis of two consecutively conducted prospective clinical studies.

PATIENTS

Patients with documented gram-negative nosocomial pneumonia were evaluated. Thirty-three patients received cefmenoxime at standard dosing and 28 patients received doses according to dual individualization methodology.

MAIN OUTCOME MEASURE

Antibiotic and infection-related costs were compared between groups. The number of hospital antibiotic days and costs incurred on those days were also evaluated. A decision model was constructed to characterize differences in treatment outcome. Probabilities within the decision tree were derived from 61 evaluable patients. Cost-effectiveness and incremental cost-effectiveness ratios were calculated. Sensitivity analysis was performed by varying outcome probabilities, antibiotic prices, and hospital room costs.

RESULTS

Antibiotic and infection-related costs (mean +/- SEM) were $848 +/- 78 for standard cefmenoxime dosing and $1123 +/- 128 for dual individualization (p < 0.05). Total hospital costs were $10,660 +/- 1432 for standard dosing and $11,709 +/- 1900 for dual individualization (p > 0.05). Median antibiotic length of stay (ALOS) was 15.2 and 12.7 days for standard and dual individualization methodologies, respectively (p > 0.05). Incremental analysis of cost-effectiveness indicated that a similar reduction in length of stay for 259 dual individualization patients would save $321,808 annually.

CONCLUSIONS

Sensitivity analysis indicates that, by reducing ALOS, dual individualization could be a cost-effective method of beta-lactam dosing for patients with pneumonia. A prospective study should be conducted to validate these findings.

Predictors of trough concentrations of oral ciprofloxacin

Patients enrolled in a fixed-dose clinical trial of oral ciprofloxacin had trough concentrations measured to document absorption and monitor compliance. The objective was to determine whether any demographic characteristics might be important predictors of the concentrations. Stepwise multivariate linear regression revealed no correlation between ciprofloxacin trough concentrations and serum creatinine, estimated creatinine clearance (Clcr), weight, height, body surface area, or gender. However, age exhibited a direct linear relationship with trough concentrations (Y in microgram/ml), Y = 0.020.age--0.541 (p < 0.003). We conclude that for patients with Clcr 30 ml/minute or above, age is a more important predictor of ciprofloxacin trough concentration than renal function. Dosage adjustment should not be arbitrary but should be guided by minimum inhibitory concentration, clinical response, and side effects.

Changes in antimicrobial agent usage resulting from interactions among clinical pharmacy, the infectious disease division, and the microbiology laboratory

Rapid reporting of culture and susceptibility data is the first of several important steps in the successful management of infected patients. As has been said many times, rapidly reported data are of little value unless the patient directly benefits. Benefit requires better overall communication and an action plan linked to timely use of these results. In 1989 the Millard Fillmore Hospital Antibiotic Review Committee developed and implemented a prototype approach to hospital wide antimicrobial management. The formulary was revised and the drug use evaluation process modified to enhance effectiveness and to lower the cost of therapy and inventory. Clinical pharmacy antimicrobial agent management specialists were then recruited to individualize patient treatments to the isolated pathogens in conjunction with the Division of Infectious Diseases. To provide the clinical pharmacy specialists with rapid and clinically useful information, a real-time computer link was created between the pharmacy (antibiotic orders) and the microbiology laboratory (culture results). Customized software was implemented to screen all patients automatically for mismatches between pathogens and drugs, or to screen for doses inappropriate to minimum inhibitory concentration or renal function. Special attention was paid to identification of opportunities to target a more appropriate narrow-spectrum regimen after culture results became available. Changes in antimicrobial regimen or dosage were made by contacting the prescribing physician. Over 90% of the recommended changes were made, and virtually all changed regimens had satisfactory clinical outcome. Real dollar expenditures for antimicrobial agents declined by > $200,000 per year. Prior to the institution of this computerized clinical management strategy, antimicrobial purchases were rising yearly at the rate of 12%-15%. The combined efforts of clinical pharmacy, microbiology, and infectious disease personnel successfully optimized antimicrobial therapy on a hospital wide basis. Antimicrobial agent optimization improved patient outcome, and the cost savings more than covered the costs of the program personnel and software.

Clinical and economic evaluation of oral ciprofloxacin after an abbreviated course of intravenous antibiotics

PURPOSE

Oral ciprofloxacin has the requisite pharmacokinetic and antibacterial properties to rival the potency of intravenous antibiotics. This study was designed to determine whether oral ciprofloxacin could abbreviate the course of intravenous antibiotics in the treatment of serious infections.

PATIENTS AND METHODS

Hospitalized adult patients were eligible for enrollment if they had a serious infection that was expected to require 8 or more days of intravenous antibiotic treatment. After conventional intravenous antibiotics were administered for 3 days, informed consent was obtained and patients were randomly assigned to either continue parenteral antibiotics (n = 53) or switch to oral ciprofloxacin 750 mg taken twice daily (n = 52). Ninety-nine of the 105 patients were evaluable for the assessment of efficacy. Clinical and bacteriologic efficacy, adverse events, and costs of the two treatments were compared.

RESULTS

The two treatment groups were comparable for demographic characteristics, types of infections, bacteria isolated, initial intravenous antibiotic regimens, and duration of antibiotic treatment. The most common infections were of the skin and skin structure; bacteremia and infections of the lower respiratory tract, urinary tract, and bone and joint were also represented. The most commonly isolated pathogens were Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli. The most frequently prescribed intravenous antibiotics before randomization included aminoglycosides, cephalosporins, vancomycin, and nafcillin; 52 evaluable patients were treated with combination therapy while 47 received monotherapy. The clinical and bacteriologic outcomes and adverse reaction frequency with oral ciprofloxacin were comparable to those of the continued intravenous antibiotic regimens. Ciprofloxacin was associated with an average cost savings of $293 per patient.

CONCLUSION

When used after 3 days of intravenous antibiotics, oral ciprofloxacin was as safe and effective as full courses of intravenous antibiotics and provided substantial cost savings.

Clinical and economic impact of oral ciprofloxacin as follow-up to parenteral antibiotics

This study assessed the effects of switching to ciprofloxacin hydrochloride in patients initially treated with parenteral antibiotics for respiratory tract (RTI), skin or skin structure (SSS), bone or joint (BJI), or urinary tract infection (UTI). A total of 766 patients from 54 institutions were concurrently monitored and the projected effect of ciprofloxacin on duration of hospitalization and parenteral therapy was assessed based on previous experiences with each type of patient. The median duration of parenteral antibiotic therapy prior to oral ciprofloxacin was 4, 6, 6, and 7.5 days; the median duration of oral ciprofloxacin prior to discharge was 2, 2, 2, and 4 days for UTI, RTI, SSS, and BJI, respectively. It was estimated that more than 70 percent of patients would have continued parenteral antibiotics on an inpatient basis and only 10 percent would have received an alternative oral agent if ciprofloxacin were not available. Use of oral ciprofloxacin significantly affected both duration of parenteral therapy and duration of hospitalization. It was estimated that 16,732 doses of parenteral antibiotics were avoided and, after subtracting the cost of oral ciprofloxacin, resulted in a likely net savings of $187 146.50. An estimated total of 2266 hospital days were saved in 418 patients, resulting in estimated savings of $739 100. Total drug plus hospitalization cost savings were projected to be $980 246.50. Further research is required to determine if, and where, more aggressive intervention will achieve additional cost savings.

Effect of acute alcohol consumption on lithium kinetics

Lithium carbonate is used in several psychiatric disorders in the context of alcohol abuse. In a randomized, double-blind, crossover study the single-dose kinetics of lithium were followed after alcohol or placebo. Lithium carbonate capsules were taken by mouth by 10 healthy young men with alcohol on one occasion and with placebo on a separate occasion (at least 7 days apart). Lithium concentrations were determined in serum and urine samples for 24 hours after dosing and served as the basis for kinetic analysis. Acute alcohol had no effect on lithium absorption, elimination, distribution, or clearance. Alcohol did, however, increase the peak serum lithium level in nine of 10 subjects, from a mean of 0.62 mEq/L in the placebo condition to 0.70 mEq/L in the alcohol condition. Our data suggest that alcohol has limited effects on lithium carbonate kinetics. The possibility of elevated serum lithium concentrations when lithium is taken with alcohol is suggested.

Effect of secobarbital on theophylline clearance

Increased clearance of theophylline after the administration of secobarbital was observed in a child receiving phenobarbital. Prior to barbiturate treatment, theophylline clearance was 4.78 ml/kg/min. Beginning 10 days after the institution of secobarbital and phenobarbital therapy, a continually increasing amount of theophylline was required to maintain therapeutic serum concentrations. After 29 days of barbiturate administration, theophylline clearance attained a peak value of 16.1 ml/kg/min, an increase of 337% from the prebarbiturate rate. During this time it was necessary to administer theophylline at a dosage four times above that usually recommended. After secobarbital was discontinued, theophylline clearance returned to 4.53 ml/kg/min. The decrease in theophylline clearance occurred while phenobarbital dosage remained stable. It is apparent that changes in secobarbital dosing were subsequently followed by changes in the clearance of theophylline.

Amphotericin B and flucytosine in the treatment of candidal cystitis

The causes, diagnosis, and treatment of candidal cystitis are reviewed. It is necessary to differentiate between colonization and infection because Candida organisms reside normally in the digestive tract of humans and do not normally exist in the urine. A diagnosis of candidal cystitis is based on a urine sample culture growth of more than 10,000 colonies/ml. Initial treatment involves removing as many of the precipitating factors as possible. The current treatment of choice is irrigation of the bladder with amphotericin B. Continuous irrigation with a three-way catheter is recommended over intermittent instillations. Oral flucytosine can be added to exert synergistic action in persistent infections, or when renal infection is suspected, or if catheterization is not desirable. The major problem with flucytosine is that many strains of Candida are initially resistant, and some strains may develop secondary resistance during the course of therapy. Because of its potential for toxicity, intravenous amphotericin B is reserved for systemic infections and for those infections refractory to more conservative therapy.