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Tilanus A, Drusano G. Inoculum-Based Dosing: A Novel Concept for Combining Time with Concentration-Dependent Antibiotics to Optimize Clinical and Microbiological Outcomes in Severe Gram Negative Sepsis. Antibiotics (Basel) 2023; 12:1581. [PMID: 37998783 PMCID: PMC10668771 DOI: 10.3390/antibiotics12111581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 10/22/2023] [Accepted: 10/23/2023] [Indexed: 11/25/2023] Open
Abstract
Certain classes of antibiotics show "concentration dependent" antimicrobial activity; higher concentrations result in increased bacterial killing rates, in contrast to "time dependent antibiotics", which show antimicrobial activity that depends on the time that antibiotic concentrations remain above the MIC. Aminoglycosides and fluoroquinolones are still widely used concentration-dependent antibiotics. These antibiotics are not hydrolyzed by beta-lactamases and are less sensitive to the inoculum effect, which can be defined as an increased MIC for the antibiotic in the presence of a relatively higher bacterial load (inoculum). In addition, they possess a relatively long Post-Antibiotic Effect (PAE), which can be defined as the absence of bacterial growth when antibiotic concentrations fall below the MIC. These characteristics make them interesting complementary antibiotics in the management of Multi-Drug Resistant (MDR) bacteria and/or (neutropenic) patients with severe sepsis. Global surveillance studies have shown that up to 90% of MDR Gram-negative bacteria still remain susceptible to aminoglycosides, depending on the susceptibility breakpoint (e.g., CLSI or EUCAST) being applied. This percentage is notably lower for fluoroquinolones but depends on the region, type of organism, and mechanism of resistance involved. Daily (high-dose) dosing of aminoglycosides for less than one week has been associated with significantly less nephro/oto toxicity and improved target attainment. Furthermore, higher-than-conventional dosing of fluoroquinolones has been linked to improved clinical outcomes. Beta-lactam antibiotics are the recommended backbone of therapy for severe sepsis. Since these antibiotics are time-dependent, the addition of a second concentration-dependent antibiotic could serve to quickly lower the bacterial inoculum, create PAE, and reduce Penicillin-Binding Protein (PBP) expression. Inadequate antibiotic levels at the site of infection, especially in the presence of high inoculum infections, have been shown to be important risk factors for inadequate resistance suppression and therapeutic failure. Therefore, in the early phase of severe sepsis, effort should be made to optimize the dose and quickly lower the inoculum. In this article, the authors propose a novel concept of "Inoculum Based Dosing" in which the decision for antibiotic dosing regimens and/or combination therapy is not only based on the PK parameters of the patient, but also on the presumed inoculum size. Once the inoculum has been lowered, indirectly reflected by clinical improvement, treatment simplification should be considered to further treat the infection.
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Affiliation(s)
- Alwin Tilanus
- Department of Infectious Diseases, Clinica Los Nogales, Calle 95 # 23-61, Bogota 110221, Colombia
| | - George Drusano
- Institute for Therapeutic Innovation, University of Florida, 6550 Sanger Road, Orlando, FL 32827, USA;
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Kumar A. An alternate pathophysiologic paradigm of sepsis and septic shock: implications for optimizing antimicrobial therapy. Virulence 2013; 5:80-97. [PMID: 24184742 PMCID: PMC3916387 DOI: 10.4161/viru.26913] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The advent of modern antimicrobial therapy following the discovery of penicillin during the 1940s yielded remarkable improvements in case fatality rate of serious infections including septic shock. Since then, pathogens have continuously evolved under selective antimicrobial pressure resulting in a lack of significant improvement in clinical effectiveness in the antimicrobial therapy of septic shock despite ever more broad-spectrum and potent drugs. In addition, although substantial effort and money has been expended on the development novel non-antimicrobial therapies of sepsis in the past 30 years, clinical progress in this regard has been limited. This review explores the possibility that the current pathophysiologic paradigm of septic shock fails to appropriately consider the primacy of the microbial burden of infection as the primary driver of septic organ dysfunction. An alternate paradigm is offered that suggests that has substantial implications for optimizing antimicrobial therapy in septic shock. This model of disease progression suggests the key to significant improvement in the outcome of septic shock may lie, in great part, with improvements in delivery of existing antimicrobials and other anti-infectious strategies. Recognition of the role of delays in administration of antimicrobial therapy in the poor outcomes of septic shock is central to this effort. However, therapeutic strategies that improve the degree of antimicrobial cidality likely also have a crucial role.
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Affiliation(s)
- Anand Kumar
- Section of Critical Care Medicine; Section of Infectious Diseases; Health Sciences Centre; Winnipeg, MB Canada
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Pharmacokinetics and pharmacodynamics of ciprofloxacin in critically ill patients after the first intravenous administration of 400 mg. Adv Med Sci 2012; 57:217-23. [PMID: 22968336 DOI: 10.2478/v10039-012-0028-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE To investigate the pharmacokinetics and pharmacodynamics of ciprofloxacin in critically ill patients after the first intravenous administration of 400 mg. MATERIAL/METHODS Plasma concentrations were measured in 20 critically ill patients (mean [SD]; age, 55.5 [16.5] years; weight, 80.3 [16.9] kg; and creatinine clearance, 110.0 [71.5] mL/min). Four blood samples were drawn at the following time points 0, 0.5, 6 , 8 hours after infusion. Ciprofloxacin concentrations were determined by high-performance liquid chromatography. RESULTS In the cases where ciprofloxacin was applied in targeted antibiotic therapy the minimum inhibitory concentrations (MIC) were ≤0.5 mg/l. The maximum and minimum plasma concentrations of ciprofloxacin were 1.74 (0.58-7.90) and 0.45 (0.16-2.96) mg/l, respectively. The main pharmacokinetic parameters for ciprofloxacin in the analyzed patients were as follows: k(el), 0.21 h-1; t(1/2kel), 3.37 h; AUC(0-inf), 10.10 mg×h/l; AUMC(0-last), 15.36 mg×h(2)/l; MRT, 1.71 h; V(d), 214.8 l; Cl, 39.70 l/h. Considering the maximum value of MIC (0.5 mg/l) only 30% and 25% of analyzed patients had desired values of the PK/PD indexes AUIC>125 and C(max) /MIC>10, respectively. CONCLUSIONS The target plasma concentrations after the first dose of ciprofloxacin were reached only in a few critically ill patients. Considerable inter-subject variability for PK/PD parameters in ICU patients requires systematic monitoring.
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Combination therapy for treatment of infections with gram-negative bacteria. Clin Microbiol Rev 2012; 25:450-70. [PMID: 22763634 DOI: 10.1128/cmr.05041-11] [Citation(s) in RCA: 539] [Impact Index Per Article: 44.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Combination antibiotic therapy for invasive infections with Gram-negative bacteria is employed in many health care facilities, especially for certain subgroups of patients, including those with neutropenia, those with infections caused by Pseudomonas aeruginosa, those with ventilator-associated pneumonia, and the severely ill. An argument can be made for empiric combination therapy, as we are witnessing a rise in infections caused by multidrug-resistant Gram-negative organisms. The wisdom of continued combination therapy after an organism is isolated and antimicrobial susceptibility data are known, however, is more controversial. The available evidence suggests that the greatest benefit of combination antibiotic therapy stems from the increased likelihood of choosing an effective agent during empiric therapy, rather than exploitation of in vitro synergy or the prevention of resistance during definitive treatment. In this review, we summarize the available data comparing monotherapy versus combination antimicrobial therapy for the treatment of infections with Gram-negative bacteria.
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5
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Abstract
Every patient with sepsis and septic shock must be evaluated thoroughly at presentation before the initiation of antibiotic therapy. However, in most situations, an abridged initial assessment focusing on critical diagnostic and management planning elements is sufficient. Intravenous antibiotics should be administered as early as possible, and always within the first hour of recognizing severe sepsis and septic shock. Broad-spectrum antibiotics must be selected with one or more agents active against likely bacterial or fungal pathogens and with good penetration into the presumed source. Antimicrobial therapy should be reevaluated daily to optimize efficacy, prevent resistance, avoid toxicity, and minimize costs. Consider combination therapy in Pseudomonas infections, and combination empiric therapy in neutropenic patients. Combination therapy should be continued for no more than 3 to 5 days and de-escalation should occur following availability of susceptibilities. The duration of antibiotic therapy typically is limited to 7 to 10 days; longer duration is considered if response is slow, if there is inadequate surgical source control, or in the case of immunologic deficiencies. Antimicrobial therapy should be stopped if infection is not considered the etiologic factor for a shock state.
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Affiliation(s)
- Anand Kumar
- Section of Critical Care Medicine, Section of Infectious Diseases, Department of Medicine, Medical Microbiology and Pharmacology/Therapeutics, University of Manitoba, Canada.
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Early combination antibiotic therapy yields improved survival compared with monotherapy in septic shock: a propensity-matched analysis. Crit Care Med 2010; 38:1773-85. [PMID: 20639750 DOI: 10.1097/ccm.0b013e3181eb3ccd] [Citation(s) in RCA: 299] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
BACKGROUND Septic shock represents the major cause of infection-associated mortality in the intensive care unit. The possibility that combination antibiotic therapy of bacterial septic shock improves outcome is controversial. Current guidelines do not recommend combination therapy except for the express purpose of broadening coverage when resistant pathogens are a concern. OBJECTIVE To evaluate the therapeutic benefit of early combination therapy comprising at least two antibiotics of different mechanisms with in vitro activity for the isolated pathogen in patients with bacterial septic shock. DESIGN Retrospective, propensity matched, multicenter, cohort study. SETTING Intensive care units of 28 academic and community hospitals in three countries between 1996 and 2007. SUBJECTS A total of 4662 eligible cases of culture-positive, bacterial septic shock treated with combination or monotherapy from which 1223 propensity-matched pairs were generated. MEASUREMENTS AND MAIN RESULTS The primary outcome of study was 28-day mortality. Using a Cox proportional hazards model, combination therapy was associated with decreased 28-day mortality (444 of 1223 [36.3%] vs. 355 of 1223 [29.0%]; hazard ratio, 0.77; 95% confidence interval, 0.67-0.88; p = .0002). The beneficial impact of combination therapy applied to both Gram-positive and Gram-negative infections but was restricted to patients treated with beta-lactams in combination with aminoglycosides, fluoroquinolones, or macrolides/clindamycin. Combination therapy was also associated with significant reductions in intensive care unit (437 of 1223 [35.7%] vs. 352 of 1223 [28.8%]; odds ratio, 0.75; 95% confidence interval, 0.63-0.92; p = .0006) and hospital mortality (584 of 1223 [47.8%] vs. 457 of 1223 [37.4%]; odds ratio, 0.69; 95% confidence interval, 0.59-0.81; p < .0001). The use of combination therapy was associated with increased ventilator (median and [interquartile range], 10 [0-25] vs. 17 [0-26]; p = .008) and pressor/inotrope-free days (median and [interquartile range], 23 [0-28] vs. 25 [0-28]; p = .007) up to 30 days. CONCLUSION Early combination antibiotic therapy is associated with decreased mortality in septic shock. Prospective randomized trials are needed.
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A survival benefit of combination antibiotic therapy for serious infections associated with sepsis and septic shock is contingent only on the risk of death: a meta-analytic/meta-regression study. Crit Care Med 2010; 38:1651-64. [PMID: 20562695 DOI: 10.1097/ccm.0b013e3181e96b91] [Citation(s) in RCA: 216] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To assess whether a potential benefit with combination antibiotic therapy is restricted to the most critically ill subset of patients, particularly those with septic shock. DATA SOURCES OVID MEDLINE (1950-October 2009), EMBASE (1980-October 2009), the Cochrane Central Register of Controlled Trials (to third quarter 2009), the ClinicalTrial.gov database, and the SCOPUS database. STUDY SELECTION Randomized or observational studies of antimicrobial therapy of serious bacterial infections potentially associated with sepsis or septic shock. Fifty studies met entry criteria. DATA EXTRACTION Study design, mortality/clinical response, and other variables were extracted independently by two reviewers. When possible, study datasets were split into mutually exclusive groups with and without shock or critical illness. DATA SYNTHESIS Although a pooled odds ratio indicated no overall mortality/clinical response benefit with combination therapy (odds ratio, 0.856; 95% confidence interval, 0.71-1.03; p = .0943; I = 45.1%), stratification of datasets by monotherapy mortality risk demonstrated substantial benefit in the most severely ill subset (monotherapy risk of death >25%; odds ratio of death, 0.51; 95% confidence interval, 0.41-0.64; I = 8.6%). Of those datasets that could be stratified by the presence of shock/critical illness, the more severely ill group consistently demonstrated increased efficacy of a combination therapy strategy (odds ratio, 0.49; 95% confidence interval, 0.35-0.70; p < .0001; I = 0%). An increased risk of death was found in low-risk patients (risk of death <or=15% in the monotherapy arm) exposed to combination therapy (odds ratio, 1.53; 95% confidence interval, 1.16-2.03; p = .003; I = 8.2%). Meta-regression indicated that efficacy of combination therapy was dependent only on the risk of death in the monotherapy group. CONCLUSION Combination antibiotic therapy improves survival and clinical response of high-risk, life-threatening infections, particularly those associated with septic shock but may be detrimental to low-risk patients.
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Kumar A. Optimizing antimicrobial therapy in sepsis and septic shock. Crit Care Clin 2010; 25:733-51, viii. [PMID: 19892250 DOI: 10.1016/j.ccc.2009.08.004] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This article reviews principles in the rational use of antibiotics in sepsis and septic shock and presents evidence-based recommendations for optimal antibiotic therapy. Every patient with sepsis and septic shock must be evaluated at presentation before the initiation of antibiotic therapy. However, in most situations, an abridged initial assessment focusing on critical diagnostic and management planning elements is sufficient. Intravenous antibiotics should be administered as early as possible, and always within the first hour of recognizing severe sepsis and septic shock. Broad-spectrum antibiotics must be selected with one or more agents active against likely bacterial or fungal pathogens and with good penetration into the presumed source. Antimicrobial therapy should be reevaluated daily to optimize efficacy, prevent resistance, avoid toxicity, and minimize costs. Consider combination therapy in Pseudomonas infections, and combination empiric therapy in neutropenic patients. Combination therapy should be continued for no more than 3 to 5 days and deescalation should occur following availability of susceptibilities. The duration of antibiotic therapy typically is limited to 7 to 10 days; longer duration is considered if response is slow, if there is inadequate surgical source control, or in the case of immunologic deficiencies. Antimicrobial therapy should be stopped if infection is not considered the etiologic factor for a shock state.
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Affiliation(s)
- Anand Kumar
- Department of Medicine, Medical Microbiology and Pharmacology/Therapeutics, University of Manitoba, Winnipeg, Manitoba, Canada.
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Fraise AP. Tigecycline: The answer to beta-lactam and fluoroquinolone resistance? J Infect 2006; 53:293-300. [PMID: 16876253 DOI: 10.1016/j.jinf.2006.05.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2006] [Revised: 05/26/2006] [Accepted: 05/26/2006] [Indexed: 10/24/2022]
Abstract
Patients with serious bacterial infections such as intra-abdominal infections and complicated skin and soft tissue infections are often treated empirically because a delay in appropriate initial antimicrobial therapy has been shown to significantly increase morbidity and mortality. Furthermore, pathogens that have developed resistance to mainstay therapeutic options are increasing in prevalence making these infections a challenge for physicians. Treatment guidelines for surgical and intra-abdominal infections recommend selection of an agent or a combination of agents with activity to cover both Gram-positive, Gram-negative organisms and anaerobes. Recommended agents include second-generation cephalosporins with anaerobic coverage, beta-lactam/beta-lactamase inhibitor agents, fluoroquinolone/metronidazole combinations and carbapenems. However, the effectiveness of these agents has come into question as once susceptible organisms are now showing signs of resistance to such antimicrobial therapies. Alternative agents specifically designed to overcome mechanisms of microbial resistance have been sought. The result of that search has been the development of a new class of antimicrobials termed glycylcyclines. The first of these novel antibacterials is tigecycline, with a broad spectrum of activity that includes coverage against vancomycin-resistant enterococci, methicillin-resistant S. aureus, and many species of multidrug-resistant Gram-negative bacteria. Tigecycline also has activity against most penicillin-susceptible and resistant Gram-positive organisms. Clinical trial experience with tigecycline has shown it to be at least as effective as current recommended regimens for the treatment of intra-abdominal infections and complicated skin and soft tissue infections. This new agent thus holds promise as an alternative to the beta-lactams and fluoroquinolones for the initial empiric treatment of serious bacterial infections.
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Affiliation(s)
- Adam P Fraise
- Microbiology Department, Sandwell & West Birmingham Hospitals NHS Trust, Dudley Road, Birmingham B18 7QH, UK.
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Solak S, Willke A, Ergönül O, Tekeli E. In vitro activity of meropenem in combination with ciprofloxacin against clinical isolates of Pseudomonas aeruginosa. Int J Antimicrob Agents 2005; 25:181-2. [PMID: 15664492 DOI: 10.1016/j.ijantimicag.2004.11.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Abstract
Anti-microbial combination therapy is a very frequently used therapeutic approach although clinical data from prospective randomized trials thus fulfilling the criteria of evidence based medicine are very rare. Rationales for the use of combination therapy are thus empirical treatment of polymicrobial infections, infections in critical ill or in immuno-compromised patients, prevention of the emerge of antibiotic resistances, utilization of a potential synergism of antibiotics directed against a certain bacterial strain, or simply despair. Prospective studies have demonstrated a superiority of combination therapy over single drug regimen in enterococcal endocarditis, and infections with gram negative rods including pseudomonas sp., but in the latter condition only if the patient is severely immuno-compromised. There is clinical indication that combination therapy may be beneficial in infections with staphylococci sp., however, well designed studies supporting this experience are largely absent. Nonetheless, antimicrobial combination therapy also harbors some risks for patients which can be referred to potential antagonism between antibiotics, accumulation of side effects, or stimulation of resistance pathways in bacteria by one drug leading to destabilization of the other one. Thus, the insightful use of combination therapy is warranted and well designed, prospective studies are urgently needed to evaluate the true benefit of combination therapy for the treatment of different infections and specific micro-organisms.
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Affiliation(s)
- Günter Weiss
- Klinische Abteilung für Allgemeine Innere Medizin, Klinische Infektiologie und Immunologie, Universitätsklinik für Innere Medizin, Anichstrasse 35, A-6020 Innsbruck.
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Lautzenhiser SJ, Fialkowski JP, Bjorling D, Rosin E. In vitro antibacterial activity of enrofloxacin and ciprofloxacin in combination against Escherichia coli and staphylococcal clinical isolates from dogs. Res Vet Sci 2001; 70:239-41. [PMID: 11676620 DOI: 10.1053/rvsc.2001.0466] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The objective of the study was to determine the in vitro interaction between enrofloxacin and ciprofloxacin against Escherichia coli and staphylococcal isolates from dogs. The microdilution checkerboard assay was used to determine the interaction of the drugs against 50 E. coli and 50 beta-haemolytic staphylococcal clinical isolates. The checkerboard assay revealed that the activity of enrofloxacin and ciprofloxacin was additive against E. coli and staphylococcal clinical isolates. It was concluded that for bacterial species against which ciprofloxacin is more potent than enrofloxacin, the in vivo transformation of enrofloxacin to ciprofloxacin may enhance the efficacy of enrofloxacin, if additivity of the drugs is confirmed in vivo.
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Affiliation(s)
- S J Lautzenhiser
- University of Wisconsin, School of Veterinary Medicine, Madison 58076, USA
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Abstract
The appetite for modification to the basic quinolone nucleus has grown logarithmically since the first quinolone was employed in clinical practice. Important structural refinements have led to expanded microbiologic activity, optimal pharmacokinetics, and increased safety profiles. The practicing clinician and researcher may glean considerable information from the quinolone structure with regard to microbiologic spectra and safety before administering these agents to patients. Although some toxicities can be ominously predictable, such as with the so-called high-risk quinolones (e.g., double-halogenated and trifluorinated quinolones), clinicians must rely on animal models of toxicity and clinical trial data to discern other toxicities (e.g., Q-Tc interval prolongation). A few quinolones enjoy a relatively clean safety profile and are well tolerated (e.g., gatifloxacin, levofloxacin, ciprofloxacin). Other quinolones may be associated with significant collateral system toxicity during therapy; however, under certain conditions, albeit rare, their potential for benefit may outweigh the existing risk. Clinafloxacin, for use in the management of lung infections caused by multiply resistant B. cepacia in cystic fibrosis patients, is an example of a risk that may be outweighed by its therapeutic benefit. Because there are many treatment alternatives within the clinician's armamentarium, the obligation is to select the safest, most therapeutically effective, and most cost-effective agent that is available. In addition to increasing mortality and morbidity, the development of toxicity or an adverse event during therapy may compromise the immediate effectiveness of treatment as well as affect the cost of the patient's care significantly. With the immediate abundance of quinolones available for use, the safest, most effective, and best-tolerated agents will likely emerge as the most appropriate therapeutic choices when a quinolone is indicated.
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Affiliation(s)
- R C Owens
- Department of Infectious Diseases, Maine Medical Center, Portland, Maine, USA
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