Impact of a pharmacist-led oral chemotherapy monitoring clinic at the South Texas Veterans Health Care System.

As cancer treatments shift from traditional intravenous chemotherapy to inclusion of oral oncolytics, there is a critical need for structured oral chemotherapy monitoring and follow-up programs. To provide continuous care and minimize clinical gaps to Veterans receiving oral chemotherapy, the hematology/oncology clinical pharmacy practitioners designed and initiated a pilot, pharmacist-driven, Oral Chemotherapy Monitoring Clinic at the South Texas Veterans Health Care System supported by an oral chemotherapy certified pharmacy technician. A retrospective evaluation of patients receiving oral chemotherapy at the South Texas Veterans Health Care System was performed before (Phase I) and after (Phase II) pilot implementation to assess the impact of an Oral Chemotherapy Monitoring Clinic on compliance with drug-specific lab and symptom monitoring. Complete monitoring was defined as 100% of recommended labs and symptoms assessed per cycle, partial monitoring was <100%, but >0%, and incomplete monitoring was defined as 0%. The primary outcome assessed the proportion of patients receiving complete monitoring in Phase II compared to Phase I. Most patients were male (94%), with a median age of 72 years. The most common oncolytic was abiraterone acetate. Overall, drug-specific baseline and follow-up laboratory and symptom monitoring was complete at a statistically significantly higher rate in Phase II compared with Phase I (p-value < 0.01). A significantly higher portion of patients in the Phase II cohort had a clinical pharmacy practitioner intervention (44% vs. 90%; p < 0.01). Monitoring for Veterans receiving oral chemotherapy was optimized with clinical pharmacy practitioner and certified pharmacy technician involvement while simultaneously alleviating Oncologist and nurse oral chemotherapy workload.

Antibiotic prescribing by age, sex, race, and ethnicity for patients admitted to the hospital with community-acquired bacterial pneumonia (CABP) in the All of Us database.

Purpose: To assess the proportion of inpatients who received guideline-concordant antibiotics for community-acquired bacterial pneumonia (CABP) in special populations of the All of Us database. Background: CABP contributes significantly to healthcare burden worldwide. The American Thoracic Society and Infectious Disease Society of America jointly published guidelines for the treatment of CABP. Guideline-concordant antibiotics for CABP are associated with better patient and cost outcomes. Methods: This was a retrospective cohort study of patients with pneumonia (n = 1608; SNOMED 233604007) from 10/1/2018 to 1/01/22 in the All of Us database. Cases were excluded for treatment setting other than inpatient, prior (within 90 days) pneumonia, receipt of intravenous antibiotics, respiratory isolation of methicillin-resistant Staphylococcus aureus (MRSA) or Pseudomonas aeruginosa, and/or other non-community-acquired types of pneumonia. Patients were grouped based on patient age, sex, race, and ethnicity. The proportion of patients on guideline-concordant therapy was compared within groups using chi-square statistics. Significant associations were assessed using multivariate logistic regression models. Results: A total of 1608 cases were included, and 45% of these patients received guideline-concordant antibiotics. Non-Hispanic White (NHW) patients vs. Black patients were associated with a 36% higher likelihood for receiving guideline-concordant antibiotics (adjusted OR, 1.36; 95% CI 1.02-1.81), whereas NHW vs. Hispanic patients were associated with a 34% lower likelihood for receiving guideline-concordant antibiotics (aOR 0.66; 0.48-0.91). Conclusion: Black patients with CABP in the All of Us database were less likely to receive guideline-concordant antibiotics, and Hispanic patients were more likely to receive guideline-concordant antibiotics, than NHW patients.

Health Equity in Patients Receiving Durvalumab for Unresectable Stage III Non-Small Cell Lung Cancer in the US Veterans Health Administration.

BACKGROUND: Real-world evidence is limited regarding the relationship between race and use of durvalumab, an immunotherapy approved for use in adults with unresectable stage III non-small cell lung cancer (NSCLC) post-chemoradiotherapy (CRT). This study aimed to evaluate if durvalumab treatment patterns differed by race in patients with unresectable stage III NSCLC in a Veterans Health Administration (VHA) population. MATERIALS AND METHODS: This was a retrospective analysis of White and Black adults with unresectable stage III NSCLC treated with durvalumab presenting to any VHA facility in the US from January 1, 2017, to June 30, 2020. Data captured included baseline characteristics and durvalumab treatment patterns, including treatment initiation delay (TID), interruption (TI), and discontinuation (TD); defined as CRT completion to durvalumab initiation greater than 42 days, greater than 28 days between durvalumab infusions, and more than 28 days from the last durvalumab dose with no new durvalumab restarts, respectively. The number of doses, duration of therapy, and adverse events were also collected. RESULTS: A total of 924 patients were included in this study (White = 726; Black = 198). Race was not a significant factor in a multivariate logistic regression model for TID (OR, 1.39; 95% CI, 0.81-2.37), TI (OR, 1.58; 95% CI, 0.90-2.76), or TD (OR, 0.84; 95% CI, 0.50-1.38). There were also no significant differences in median (interquartile range [IQR]) number of doses (White: 15 [7-24], Black: 18 [7-25]; P = .25) or median (IQR) duration of therapy (White: 8.7 months [2.9-11.8], Black: 9.8 months [3.6-12.0]; P = .08), although Black patients were less likely to experience an immune-related adverse event (28% vs. 36%, P = .03) and less likely to experience pneumonitis (7% vs. 14%, P < .01). CONCLUSION: Race was not found to be linked with TID, TI, or TD in this real-world study of patients with unresectable stage III NSCLC treated with durvalumab at the VHA.

Know your medicine: A novel student-led community service learning program.

INTRODUCTION: The objective of this article is to describe the efforts of the student pharmacist organization called Know Your Medicine (KYM) as they conduct medication therapy management (MTM) for older adults and underserved communities. METHODS: Patients brought medications, immunization records, and health concerns to KYM events during academic years 2012-2013 and 2013-2014. Student pharmacists performed health screenings, created personalized medication records (PMR), made recommendations, created personal action plans (PAP), and conducted follow-up phone calls. RESULTS: Student pharmacists provided MTM services for a total of 107 patients. The mean duration of a KYM appointment was 62±21min, and student pharmacists provided a mean of 3.5±2.1 recommendations per patient. Patients had a mean age of 78±11 years, 4.5±3.2 disease states, 6.9±4.6 prescriptions, 1.9±1.9 OTC medications, and 2.8±2.6 vitamins or herbals. At the time of the follow-up phone call, a mean of 2.6±1.9 recommendations per patient had been followed. DISCUSSION AND CONCLUSIONS: Student pharmacists successfully implemented a new MTM program for older adults and underserved communities. This program can serve as an example of how other pharmacy colleges and schools might implement MTM training and real-world MTM experience for their student pharmacists.

Comparative value of four measures of retention in expert care in predicting clinical outcomes and health care utilization in HIV patients.

This study compared the ability of four measures of patient retention in HIV expert care to predict clinical outcomes. This retrospective study examined Veterans Health Administration (VHA) beneficiaries with HIV (ICD-9-CM codes 042 or V08) receiving expert care (defined as HIV-1 RNA viral load and CD4 cell count tests occurring within one week of each other) at VHA facilities from October 1, 2006, to September 30, 2008. Patients were ≥18 years old and continuous VHA users for at least 24 months after entry into expert care. Retention measures included: Annual Appointments (≥2 appointments annually at least 60 days apart), Missed Appointments (missed ≥25% of appointments), Infrequent Appointments (>6 months without an appointment), and Missed or Infrequent Appointments (missed ≥25% of appointments or >6 months without an appointment). Multivariable nominal logistic regression models were used to determine associations between retention measures and outcomes. Overall, 8,845 patients met study criteria. At baseline, 64% of patients were virologically suppressed and 37% had a CD4 cell count >500 cells/mm3. At 24 months, 82% were virologically suppressed and 46% had a CD4 cell count >500 cells/mm3. During follow-up, 13% progressed to AIDS, 48% visited the emergency department (ED), 28% were hospitalized, and 0.3% died. All four retention measures were associated with virologic suppression and antiretroviral therapy initiation at 24 months follow-up. Annual Appointments correlated positively with CD4 cell count >500 cells/mm3. Missed Appointments was predictive of all primary and secondary outcomes, including CD4 cell count ≤500 cells/mm3, progression to AIDS, ED visit, and hospitalization. Missed Appointments was the only measure to predict all primary and secondary outcomes. This finding could be useful to health care providers and public health organizations as they seek ways to optimize the health of HIV patients.

Impact of a new method of warfarin management on patient satisfaction, time, and cost.

STUDY OBJECTIVE: International normalized ratio self-testing with online remote monitoring and management (STORM2) is an alternative to anticoagulation clinic management, but the patient's perspective of this method has not been evaluated in the United States; thus we sought to evaluate the impact of STORM2 on patient satisfaction, time, and cost. DESIGN: Prospective pre- and postintervention study. SETTING: Freestanding clinical research center. PATIENTS: Forty-three patients treated with long-term warfarin therapy and monitored initially in the anticoagulation clinic setting and then with STORM2, referred from 11 medical practices. INTERVENTION: Patients were asked to complete a survey and the Duke Anticoagulation Satisfaction Scale (DASS) before (at baseline) and after at least 3 months of STORM2 (at follow-up). MEASUREMENTS AND MAIN RESULTS: Patient satisfaction and time were assessed by survey and the DASS. Costs were measured from the patient's perspective. Overall 90% of responders preferred STORM2 to traditional clinic management. The DASS questions indicated that patients were more satisfied with their anticoagulation treatment and more likely to recommend oral anticoagulation to a friend after experiencing STORM2. In addition, patients found STORM2 to be less complicated and more convenient than traditional clinic management. For each traditional monthly visit, patients drove 20 miles and expended a total of 1.8 hours; using 55¢/mile for mileage reimbursement and $15/hour for lost wages, the cost for each visit was $38. The total cost for four STORM2 visits per month was $10, for a net savings of $28 per patient per month. A total of 76% of patients were willing to pay additional money to eliminate a monthly clinic visit. CONCLUSION: STORM2 is more convenient, less complicated, preferred by patients, and saves patients time and money compared with clinic management.

Treatment failure and costs in patients with methicillin-resistant Staphylococcus aureus (MRSA) skin and soft tissue infections: a South Texas Ambulatory Research Network (STARNet) study.

OBJECTIVE: To measure the incidence of treatment failure and associated costs in patients with methicillin-resistant Staphylococcus aureus skin and soft tissue infections (SSTIs). METHODS: This was a prospective, observational study in 13 primary care clinics. Primary care providers collected clinical data, wound swabs, and 90-day follow-up information. Patients were considered to have "moderate or complicated" SSTIs if they had a lesion ≥5 cm in diameter or diabetes mellitus. Treatment failure was evaluated within 90 days of the initial visit. Cost estimates were obtained from federal sources. RESULTS: Overall, treatment failure occurred in 21% of patients (21 of 98) at a mean additional cost of $1,933.71 per patient. In a subgroup analysis of patients who received incision and drainage, those with moderate or complicated SSTIs had higher rates of treatment failure than those with mild or uncomplicated SSTIs (36% vs. 10%; P=.04). CONCLUSIONS: One in 5 patients presenting to a primary care clinic for a methicillin-resistant S. aureus SSTI will likely require additional interventions at an associated cost of almost $2,000 per patient. Baseline risk stratification and new treatment approaches are needed to reduce treatment failures and costs in the primary care setting.

A clinical pathway for community-acquired pneumonia: an observational cohort study.

BACKGROUND: Six hospitals instituted a voluntary, system-wide, pathway for community acquired pneumonia (CAP). We proposed this study to determine the impact of pathway antibiotics on patient survival, hospital length of stay (LOS), and total hospital cost. METHODS: Data were collected for adults from six U.S. hospitals with a principal CAP discharge diagnosis code, a chest infiltrate, and medical notes indicative of CAP from 2005-2007. Pathway and non-pathway cohorts were assigned according to antibiotics received within 48 hours of admission. Pathway antibiotics included levofloxacin 750 mg monotherapy or ceftriaxone 1000 mg plus azithromycin 500 mg daily. Multivariable regression models assessed 90-day mortality, hospital LOS, total hospital cost, and total pharmacy cost. RESULTS: Overall, 792 patients met study criteria. Of these, 505 (64%) received pathway antibiotics and 287 (36%) received non-pathway antibiotics. Adjusted means and p-values were derived from Least Squares regression models that included Pneumonia Severity Index risk class, patient age, heart failure, chronic obstructive pulmonary disease, and admitting hospital as covariates. After adjustment, patients who received pathway antibiotics experienced lower adjusted 90-day mortality (p = 0.02), shorter mean hospital LOS (3.9 vs. 5.0 days, p < 0.01), lower mean hospital costs ($2,485 vs. $3,281, p = 0.02), and similar mean pharmacy costs ($356 vs. $442, p = 0.11). CONCLUSIONS: Pathway antibiotics were associated with improved patient survival, hospital LOS, and total hospital cost for patients admitted to the hospital with CAP.

Fluoroquinolones in community-acquired pneumonia: guide to selection and appropriate use.

Fluoroquinolone use has dramatically increased since the introduction of the first respiratory fluoroquinolone in the late 1990s. Over a relatively brief period of time, the respiratory fluoroquinolones have supplanted other first-line options as the predominant community-acquired pneumonia (CAP) therapy in hospitals. This article discusses the rise of the fluoroquinolone era, debates the comparative effectiveness of fluoroquinolones for CAP therapy, examines fluoroquinolone resistance and adverse drug reactions, and discusses new trends in pneumonia epidemiology and outcomes assessment. Overall, published data suggest that fluoroquinolone monotherapy is associated with improved patient survival compared with ß-lactam monotherapy and similar survival to ß-lactam plus macrolide combination therapy. Fluoroquinolone monotherapy may be associated with shorter hospital length of stay compared with ß-lactam plus macrolide combination therapy, particularly in severe pneumonia or with high-dose therapy. There is insufficient evidence to conclude that any individual fluoroquinolone therapy is better than another with regards to patient mortality. Fluoroquinolones are generally well tolerated and Streptococcus pneumoniae resistance remains low; however, rare but serious adverse effects have been reported. Some members of the fluoroquinolone class have been removed from the market amidst safety concerns. Pneumonia classifications have changed and antipseudomonal fluoroquinolones may have a role in healthcare-associated pneumonia when administered in combination with other antipseudomonal and anti-methicillin-resistant Staphylococcus aureus therapies.

Health economics of use fluoroquinolones to treat patients with community-acquired pneumonia.

Respiratory diseases account for approximately 10% of all hospital admissions in the United States. Pneumonia constitutes 35% of these cases, with an average length of stay (LOS) of 5.1 days. It is estimated that $8.4 billion to $10 billion of all annual US hospital expenditures are attributable to community-acquired pneumonia (CAP). As such, medical decisions, including empiric antibiotic choice, potentially exert an impact on hospital LOS and associated costs. In this review, we focus on the empiric antibiotic choices and associated costs of treatment for hospitalized patients with CAP, focusing on the use of fluoroquinolone therapy as recommended by the CAP guidelines.

Antimicrobial breakpoints for gram-negative aerobic bacteria based on pharmacokinetic-pharmacodynamic models with Monte Carlo simulation.

OBJECTIVES: This study describes a comprehensive programme designed to develop pharmacokinetic-pharmacodynamic (PK-PD) breakpoints for numerous antimicrobial classes against key gram-negative aerobic bacteria. METHODS: A 10,000 subject Monte Carlo simulation was constructed for 13 antimicrobials (21 dosing regimens). Published pharmacokinetic data and protein binding were varied according to log-normal and uniform distributions. MICs were fixed at single values from 0.03 to 64 mg/L. The PK-PD susceptible breakpoint was defined as the MIC at which the probability of target attainment was > or = 90%. PK-PD, CLSI and European Committee on Antimicrobial Susceptibility Testing breakpoints were applied to MICs from the 2005 worldwide Meropenem Yearly Susceptibility Test Information Collection database to evaluate the impact of breakpoint discrepancies. RESULTS: PK-PD breakpoints were within one dilution of the CLSI and European breakpoints for all antimicrobials tested--with a few exceptions. When discrepancies were noted, the PK-PD breakpoint was lower than the CLSI breakpoint [ceftriaxone (0.5 versus 8 mg/L), ertapenem (0.25 versus 2 mg/L), ciprofloxacin (0.125 versus 1 mg/L) and levofloxacin (0.25-0.5 versus 2 mg/L)] and higher than the European breakpoint [ceftazidime (4-8 versus 1 mg/L), aztreonam (4-8 versus 1 mg/L), although ciprofloxacin was an exception to this pattern (0.125 versus 0.5-1 mg/L)]. For Enterobacteriaceae, breakpoint discrepancies resulted in modest (< or = 10%) differences in the percentages susceptible. In contrast, large (> 15%) discrepancies were noted for Pseudomonas aeruginosa and Acinetobacter baumannii. CONCLUSIONS: Breakpoint agreement exists for imipenem, meropenem and the aminoglycosides. In contrast, discrepancies exist for piperacillin/tazobactam, cephalosporins, ertapenem, aztreonam and the fluoroquinolones. These discrepancies are most pronounced for P. aeruginosa and A. baumannii.

Pharmacokinetic/pharmacodynamic modeling to predict in vivo effectiveness of various dosing regimens of piperacillin/tazobactam and piperacillin monotherapy against gram-negative pulmonary isolates from patients managed in intensive care units in 2002.

OBJECTIVE: This study compared the pharmacokinetic/pharmacodynamic (PK/PD) properties of piperacillin/tazobactam (PTZ) combination treatment with those of piperacillin (PIP) monotherapy against clinical gram-negative pulmonary isolates from US patients treated in intensive care units. METHODS: Computer modeling was used to integrate national in vitro microbiologic data from 2002 with pharmacokinetic data from published studies in healthy volunteers. PTZ (3.375 g q4h, 3.375 g q6h, 4.5 g q6h, and 4.5 g q8h) and PIP (3 g q4h, 3 g q6h, 4 g q6h, and 4 g q8h) were modeled using Monte Carlo simulations. The cumulative fraction of response (CFR) was determined for percentage of time that the free serum concentration remained above the MIC of >or=30% (bacteriostatic) and >or=50% (bactericidal). Because simulated comparisons with an artificially derived sample size were used, statistical methods were not applied. RESULTS: Overall, 2584 gram-negative pulmonary isolates were evaluated, including Enterobacteriaceae (n = 1430), Pseudomonas aeruginosa (n = 799), Acinetobacter baumannii (n = 179), and "other" (n = 176). The percents susceptible with PTZ and PIP were as follows: Enterobacteriaceae, 86% and 66%, respectively; P aeruginosa, 89% and 84%; and A baumannii, 47% and 34%. CFR rates with PTZ were numerically higher than those with PIP against Enterobacteriaceae (ranges, 86%-89% and 66%-73%, respectively) and A baumannii (47%-53% and 33%-42%), but not against P aeruginosa (79%-84% and 75%-81%). CONCLUSION: Results from PK/PD models with Monte Carlo simulation suggested that susceptibility differences among these selected gram-negative isolates collected in 2002 may be of sufficient magnitude to result in notable PK/PD differences between PTZ and PIP.

Influence of culture site-specific MIC distributions on the pharmacokinetic and pharmacodynamic properties of piperacillin/tazobactam and piperacillin: a data analysis.

BACKGROUND: Investigators who perform pharmacokinetic/pharmacodynamic (PK-PD) modeling with Monte Carlo simulation have historically not stratified microbiological data by culture site. This lack of stratification might be problematic if susceptibility patterns differ among sites and might lead to differences in PK-PD. OBJECTIVE: This study compared the PK-PD of 2 antimicrobial regimens against 5 gram-negative bacterial species form 3 culture sites. METHODS: This data analysis was performed at the Department of Pharmacology, The University of Texas Health Science Center, San Antonio, Texas. Blood, pulmonary (ie, bronchial, endotracheal, lung, respiratory, sputum, and tracheal secretions), and wound distributions of MICs were extracted from the 2002 Intensive Care Unit Surveillance System database. Bacteria included Acinetobacter baumannii, Enterobacter cloacae, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. The PK properties of piperacillin/tazobactam (3.375 g every 4 hours) and piperacillin (3 g every 4 hours) were obtained from studies in healthy volunteers. Monte Carlo simulation was used in 10,000 patients for each antimicrobial-bacteria-culture site combination. The cumulative fraction of response (CFR) for a free percentage time above the MIC of > or =50% was determined for each combination, and a clinically significant difference was defined a priori as > or =10%. RESULTS: Data from 2408 pulmonary, 490 blood, and 242 wound isolates were included. For piperacillin/tazobactam, the CFR varied <10% by culture site in all 5 bacterial species. Site-specific differences were noted in MIC50 for piperacillin versus E cloacae and E coli and MIC90 for piperacillin/tazobactam versus K pneumoniae and P aeruginosa. Likewise, for piperacillin, the CFR was similar among the 3 culture sites for P aeruginosa. However, the CFR for piperacillin varied by > or =10% for A baumannii (blood > wound), E cloacae (pulmonary > blood), E coli (pulmonary and blood > wound), and K pneumoniae (wound > blood). CONCLUSIONS: The PK-PD models based on PK properties found in healthy humans and site-specific MIC distributions in this study suggest that for piperacillin, culture-site differences subsequently resulted in CFR differences that exceeded a predetermined level of clinical significance. Furthermore, these data suggest that traditional reporting strategies for microbiological data (ie, MIC50 and MIC90) might fail to adequately characterize the MIC population.

Pharmacodynamic analysis of ceftriaxone, gatifloxacin,and levofloxacin against Streptococcus pneumoniae with the use of Monte Carlo simulation.

STUDY OBJECTIVE: To evaluate the pharmacodynamics of four intravenous antimicrobial regimens-ceftriaxone 1 g, gatifloxacin 400 mg, levofloxacin 500 mg, and levofloxacin 750 mg, each every 24 hours-against recent Streptococcus pneumoniae isolates. DESIGN: Pharmacodynamic analysis using Monte Carlo simulation. DATA SOURCE: The Surveillance Network (TSN) 2002 database. MEASUREMENTS AND MAIN RESULTS: Streptococcus pneumoniae isolates (7866 isolates) were stratified according to penicillin susceptibilities as follows: susceptible (4593), intermediate (1986), and resistant (1287). Risk analysis software was used to simulate 10,000 patients by integrating published pharmacokinetic parameters, their variability, and minimum inhibitory concentration (MIC) distributions from the TSN database. Probability of target attainment was determined for percentage of time above the MIC (%T > MIC) from 0-100% for ceftriaxone and area under the concentration-time curve (AUC):MIC ratio from 0-150 for the fluoroquinolones. For ceftriaxone, probability of target attainment remained 90% or greater against the three isolate groups until a %T > MIC of 70% or greater, and it remained 90% or greater against susceptible and intermediate isolates over the entire interval (%T > MIC 0-100%). For levofloxacin 500 mg, probability of target attainment was 90% at an AUC:MIC < or = 30, but the curve declined sharply with further increases in pharmacodynamic target. Levofloxacin 750 mg achieved a probability of target attainment of 99% at an AUC:MIC ratio < or = 30; the probability remained approximately 90% until a target of 70 or greater, when it declined steeply. Gatifloxacin demonstrated a high probability (99%) of target attainment at an AUC:MIC ratio < or = 30, and it remained above 90% until a target of 70. CONCLUSION: Ceftriaxone maintained high probability of target attainment over a broad range of pharmacodynamic targets regardless of penicillin susceptibility (%T > MIC 0-60%). Levofloxacin 500 mg maintained high probability of target attainment for AUC:MIC ratios 0-30; whereas, levofloxacin 750 mg and gatifloxacin maintained high probability of target attainment for AUC:MIC ratios 0-60. Rate of decline in the pharmacodynamic curve was most pronounced for the two levofloxacin regimens and more gradual for gatifloxacin and ceftriaxone.

Pharmacodynamic modeling of carbapenems and fluoroquinolones against bacteria that produce extended-spectrum beta-lactamases.

BACKGROUND: Bacteria that produce extended-spectrum beta-lactamases (ESBLs) are resistant to penicillins,cephalosporins, and monobactams. The results of clinical studies suggest that the carbapenems imipenem and meropenem may be effective against bacteria that produce ESBLs, although it is not known whether the new once-daily carbapenem ertapenem or the fluoroquinolones are useful against infections caused by ESBL-producing bacteria. OBJECTIVE: The present study compared the simulated pharmacodynamics of the carbapenems imipenem,meropenem, and ertapenem; the simulated pharmacodynamics of the fluoroquinolones levofloxacin, gatifloxacin, and ciprofloxacin with those of the carbapenems; and the simulated pharmacodynamics of levofloxacin 750 mg with those of levofloxacin 500 mg, all against gram-negative isolates that did and did not produce ESBLs METHODS: Pharmacokinetic data were obtained from studies in healthy humans. Minimum inhibitory concentrationsMICs) for bacteria that did and did not produce ESBLs were determined in triplicate using broth-microdilution techniques as recommended by National Committee for Clinical Laboratory Standards guidelines. Monte Carlo simulation was used to construct pharmacodynamic models for imipenem, meropenem, ertapenem, levofloxacin, gatifloxacin, and ciprofloxacin. Pharmacodynamic measures of interest were the probability of the free concentration remaining above the MIC >-40% of the time (T>MIC > or =40%) for carbapenems and the likelihood of achieving a free AUC:MIC ratio > or =125 for fluoroquinolones. RESULTS: MICs were determined for 39 isolates that produced ESBLs and 45 isolates that did not Bacteria that did not produce ESBLs were > or =93% susceptible to all carbapenems and fluoroquinolones tested. Among bacteria that produced ESBLs, rates of susceptibility to the specific agents were as follows: imipenem, 100%; meropenem, 97%; ertapenem, 87%; levofloxacin, 54%; gatifloxacin, 44%; and ciprofloxacin, 36%. In the pharmacodynamic models, imipenem and meropenem had an equal likelihood of achieving a free T>MIC > or =40% against bacteria that produced ESBLs (> or =97%) and bacteria that did not produce ESBLs (> or =98%). In contrast, the likelihood of ertapenem achieving a free T>MIC > or =40% was lower against bacteria that produced ESBLs (78%) than against bacteria that did not produce ESBLs (94%). Similarly, the fluoroquinolones were less likely to achieve a free AUC:MIC ratio > or =125 against bacteria that produced ESBLs (2%-13%) than against bacteria that did not produce ESBLs (85%-91%). CONCLUSIONS: Carbapenems had superior in vitro activity against bacteria that produced ESBLs compared with fluoroquinolones. Pharmacodynamic modeling based on local ESBL-producing isolates and pharmacokinetic data from healthy humans indicated that imipenem and meropenem may have a greater likelihood of achieving pharmacodynamic targets against bacteria that produce ESBLs than ertapenem or fluoroquinolones.