Activity of Moxifloxacin against Mycobacterium tuberculosis in Acid Phase and Nonreplicative-Persister Phenotype Phase in a Hollow-Fiber Infection Model

ABSTRACT A major goal for improving tuberculosis therapy is to identify drug regimens with improved efficacy and shorter treatment durations. Shorter therapies improve patient adherence to the antibiotic regimens, which, in turn, decreases resistance emergence. Mycobacterium tuberculosis exists in multiple metabolic states. At the initiation of therapy, the bulk of the population is in log-phase growth. Consequently, it is logical to focus initial therapy on those organisms. Moxifloxacin has good early bactericidal activity against log-phase bacteria and is a logical component of initial therapy. It would be optimal if this agent also possessed activity against acid-phase and nonreplicative-persister (NRP) phenotype organisms. In our hollow-fiber infection model, we studied multiple exposures to moxifloxacin (equivalent to 200 mg to 800 mg daily) against strain H37Rv in the acid phase and against strain 18b in streptomycin starvation, which is a model for NRP-phase organisms. Moxifloxacin possesses good activity against acid-phase organisms, generating cell killing of 3.75 log10(CFU/ml) (200 mg daily) to 5.16 log10(CFU/ml) (800 mg daily) over the 28 days of the experiment. Moxifloxacin also has activity against streptomycin-starved strain 18b. The 400- to 800-mg daily regimens achieved extinction at day 28, while the no-treatment control still had 1.96 log10(CFU/ml) culturable. The lowest dose (200 mg daily) still had 0.7 log10(CFU/ml) measurable at day 28, a net kill of 1.26 log10(CFU/ml). Moxifloxacin is an attractive agent for early therapy, because it possesses activity against three metabolic states of M. tuberculosis.

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Linezolid Kills Acid-Phase and Nonreplicative-Persister-Phase Mycobacterium tuberculosis in a Hollow-Fiber Infection Model

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00221-18 ◽

2018 ◽

Vol 62 (8) ◽

Cited By ~ 4

Author(s):

G. L. Drusano ◽

Jenny Myrick ◽

Michael Maynard ◽

Jocelyn Nole ◽

Brandon Duncanson ◽

...

Keyword(s):

Mycobacterium Tuberculosis ◽

Hollow Fiber ◽

Infection Model ◽

Phase Growth ◽

Minimum Concentration ◽

Once Daily ◽

Content Type ◽

Metabolic States ◽

Daily Dose ◽

Clear Dose Response

ABSTRACT The therapy for treatment of Mycobacterium tuberculosis infections is long and arduous. It has been hypothesized that the therapy duration is driven primarily by populations of organisms in different metabolic states that replicate slowly or not at all (acid-phase and nonreplicative-persister [NRP]-phase organisms). Linezolid is an oxazolidinone antimicrobial with substantial activity against Log-phase M. tuberculosis. Here, we examined organisms in acid-phase growth and nonreplicative-persister-phenotype growth and determined the effect of differing clinically relevant exposures to linezolid in a hollow-fiber infection model (HFIM). The endpoints measured were bacterial kill over 29 days and whether organisms that were less susceptible to linezolid could be recovered during that period. In addition, we evaluated the effect of administration schedule on linezolid activity, contrasting daily administration with administration of twice the daily dose every other day. Linezolid demonstrated robust activity when administered daily against both acid-phase and NRP-phase organisms. We demonstrated a clear dose response, with 900 mg of linezolid daily generating ≥3 Log(CFU/ml) killing of acid-phase and NRP-phase M. tuberculosis over 29 days. Amplification of a population less susceptible to linezolid was not seen. Activity was reduced with every 48-h dosing, indicating that the minimum concentration (Cmin)/MIC ratio drove the microbiological effect. We conclude that once-daily linezolid dosing has substantial activity against M. tuberculosis in acid-phase and NRP-phase metabolic states. Other studies have shown activity against Log-phase M. tuberculosis. Linezolid is a valuable addition to the therapeutic armamentarium for M. tuberculosis and has the potential for substantially shortening therapy duration.

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Effect of Coadministration of Moxifloxacin and Rifampin on Mycobacterium tuberculosis in a Murine Aerosol Infection Model

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.06383-11 ◽

2012 ◽

Vol 56 (6) ◽

pp. 3054-3057 ◽

Cited By ~ 18

Author(s):

V. Balasubramanian ◽

S. Solapure ◽

S. Gaonkar ◽

K. N. Mahesh Kumar ◽

R. K. Shandil ◽

...

Keyword(s):

Mycobacterium Tuberculosis ◽

Hollow Fiber ◽

Lung Model ◽

Control Group ◽

Infection Model ◽

Content Type ◽

Days Of Therapy ◽

Cell Kill ◽

Aerosol Infection

ABSTRACTCoadministration of moxifloxacin and rifampin was evaluated in a murine model ofMycobacterium tuberculosispulmonary infection to determine whether the finding of antagonism documented in a hollow-fiber infection model could be recapitulatedin vivo. Colony counts were followed in a no-treatment control group, groups administered moxifloxacin or rifampin monotherapy, and a group administered a combination of the two agents. Following 18 days of once-daily oral administration to mice infected withM. tuberculosis, there was a reduction in the plasma exposure to rifampin that decreased further when rifampin was coadministered with moxifloxacin. Pharmacodynamic analysis demonstrated a mild antagonistic interaction between moxifloxacin and rifampin with respect to cell kill in the mouse model for tuberculosis (TB). No emergence of resistance was noted over 28 days of therapy, even with monotherapy. This was true even though one of the agents in the combination (moxifloxacin) induces error-prone replication. The previously noted antagonism with respect to cell kill shown in the hollow-fiber infection model was recapitulated in the murine TB lung model, although to a lesser extent.

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Pharmacodynamics of Ceftazidime plus Avibactam against KPC-2-Bearing Isolates of Klebsiella pneumoniae in a Hollow Fiber Infection Model

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00462-19 ◽

2019 ◽

Vol 63 (8) ◽

Cited By ~ 1

Author(s):

G. L. Drusano ◽

Ryan K. Shields ◽

Nino Mtchedlidze ◽

M. Hong Nguyen ◽

Cornelius J. Clancy ◽

...

Keyword(s):

Klebsiella Pneumoniae ◽

Hollow Fiber ◽

Model Fit ◽

Infection Model ◽

Bacterial Burden ◽

Treatment Control ◽

Early Therapy ◽

Content Type ◽

Kill Rate ◽

Potent Inhibitory Activity

ABSTRACT Ceftazidime-avibactam (CAZ/AVI) combines ceftazidime with a diazabicyclooctane non-β-lactam β-lactamase inhibitor. This has potent inhibitory activity against KPC-type enzymes. We studied activity of clinically relevant regimens of CAZ/AVI against two KPC-2-bearing Klebsiella pneumoniae isolates (sequence type 258 recovered sequentially from the same patient) with and without ompK36 mutations in a hollow fiber infection model. The baseline total bacterial burden exceeded 109 CFU. For both isolates, there was early multi-log CFU/ml reductions in the bacterial burden for all regimens. Bacterial subpopulations with reduced susceptibilities to CAZ/AVI were isolated only from the no-treatment control arms. All CAZ/AVI regimens resulted in undetectable colony counts between days 6 and 8. At day 10, the total volume of each CAZ/AVI arm was plated, with no organisms recovered from any regimen, documenting complete eradication. A population model was fit to avibactam concentrations and total colony count outputs. The model fit was acceptable and demonstrated a large kill rate constant (Kkill = 6.29 h−1) and a relatively low avibactam concentration at which kill rate was half maximal (C50 = 2.19 mg/liter), concordant with the observed bacterial burden decline. A threshold analysis identified time > 4 mg/liter of avibactam as the index most closely linked to bacterial burden decline. Given the clinical outcomes seen with KPC-bearing organisms and the toxicities that occur when patients are treated with currently available polymyxins, drugs such as CAZ/AVI should have a prominent place in early therapy.

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Higher Dosing of Rifamycins Does Not Increase Activity against Mycobacterium tuberculosis in the Hollow-Fiber Infection Model

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02255-20 ◽

2021 ◽

Vol 65 (4) ◽

Author(s):

E. D. Pieterman ◽

S. van den Berg ◽

A. van der Meijden ◽

E. M. Svensson ◽

H. I. Bax ◽

...

Keyword(s):

Mycobacterium Tuberculosis ◽

Drug Development ◽

Hollow Fiber ◽

Standard Dose ◽

Free Fraction ◽

Infection Model ◽

Preclinical Model ◽

Content Type ◽

Development Pipeline

ABSTRACT Improvements in the translational value of preclinical models can allow more-successful and more-focused research on shortening the duration of tuberculosis treatment. Although the hollow-fiber infection model (HFIM) is considered a valuable addition to the drug development pipeline, its exact role has not been fully determined yet. Since the strategy of increasing the dose of rifamycins is being evaluated for its treatment-shortening potential, additional in vitro modeling is important. Therefore, we assessed increased dosing of rifampin and rifapentine in our HFIM in order to gain more insight into the place of the HFIM in the drug development pipeline. Total and free-fraction concentrations corresponding to daily dosing of 2.7, 10, and 50 mg of rifampin/kg of body weight, as well as 600 mg and 1,500 mg rifapentine, were assessed in our HFIM using the Mycobacterium tuberculosis H37Rv strain. Drug activity and the emergence of drug resistance were assessed by CFU counting and subsequent mathematical modeling over 14 days, and pharmacokinetic exposures were checked. We found that increasing rifampin exposure above what is expected with the standard dose did not result in higher antimycobacterial activity. For rifapentine, only the highest concentration showed increased activity, but the clinical relevance of this observation is questionable. Moreover, for both drugs, the emergence of resistance was unrelated to exposure. In conclusion, in the simplest experimental setup, the results of the HFIM did not fully correspond to preexisting clinical data. The inclusion of additional parameters and readouts in this preclinical model could be of interest for proper assessment of the translational value of the HFIM.

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Combating Carbapenem-ResistantAcinetobacter baumanniiby an Optimized Imipenem-plus-Tobramycin Dosage Regimen: Prospective Validation via Hollow-Fiber Infection and Mathematical Modeling

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02053-17 ◽

2018 ◽

Vol 62 (4) ◽

Cited By ~ 7

Author(s):

Cornelia B. Landersdorfer ◽

Rajbharan Yadav ◽

Kate E. Rogers ◽

Tae Hwan Kim ◽

Beom Soo Shin ◽

...

Keyword(s):

Mathematical Modeling ◽

Acinetobacter Baumannii ◽

Hollow Fiber ◽

Dosage Regimen ◽

Infection Model ◽

Bacterial Killing ◽

Content Type ◽

Carbapenem Resistant

ABSTRACTWe aimed to prospectively validate an optimized combination dosage regimen against a clinical carbapenem-resistantAcinetobacter baumannii(CRAB) isolate (imipenem MIC, 32 mg/liter; tobramycin MIC, 2 mg/liter). Imipenem at constant concentrations (7.6, 13.4, and 23.3 mg/liter, reflecting a range of clearances) was simulated in a 7-day hollow-fiber infection model (inoculum, ∼107.2CFU/ml) with and without tobramycin (7 mg/kg q24h, 0.5-h infusions). While monotherapies achieved no killing or failed by 24 h, this rationally optimized combination achieved >5 log10bacterial killing and suppressed resistance.

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Optimization and Evaluation of Piperacillin-Tobramycin Combination Dosage Regimens againstPseudomonas aeruginosafor Patients with Altered Pharmacokinetics via the Hollow-Fiber Infection Model and Mechanism-Based Modeling

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00078-18 ◽

2018 ◽

Vol 62 (5) ◽

Cited By ~ 4

Author(s):

Rajbharan Yadav ◽

Kate E. Rogers ◽

Phillip J. Bergen ◽

Jürgen B. Bulitta ◽

Carl M. J. Kirkpatrick ◽

...

Keyword(s):

Critically Ill ◽

Hollow Fiber ◽

Critically Ill Patient ◽

Infection Model ◽

Case Scenario ◽

Bacterial Killing ◽

Worst Case ◽

Content Type ◽

Dosage Regimens ◽

Time Kill

ABSTRACTAugmented renal clearance (ARC) in critically ill patients can result in suboptimal drug exposures and treatment failure. Combination dosage regimens accounting for ARC have never been optimized and evaluated againstPseudomonas aeruginosaby use of the hollow-fiber infection model (HFIM). Using aP. aeruginosaisolate from a critically ill patient and static-concentration time-kill experiments (SCTKs), we studied clinically relevant piperacillin and tobramycin concentrations, alone and in combinations, against two inocula (105.8and 107.6CFU/ml) over 72 h. We subsequently evaluated the effects of optimized piperacillin (4 g every 4 h [q4h], given as 0.5-h infusions) plus tobramycin (5 mg/kg of body weight q24h, 7 mg/kg q24h, or 10 mg/kg q48h, given as 0.5-h infusions) regimens on killing and regrowth in the HFIM, simulating a creatinine clearance of 250 ml/min. Mechanism-based modeling was performed in S-ADAPT. In SCTKs, piperacillin plus tobramycin (except combinations with 8 mg/liter tobramycin and against the low inoculum) achieved synergistic killing (≥2 log10versus the most active monotherapy at 48 h and 72 h) and prevented regrowth. Piperacillin monotherapy (4 g q4h) in the HFIM provided 2.4-log10initial killing followed by regrowth at 24 h and resistance emergence. Tobramycin monotherapies displayed rapid initial killing (≥5 log10at 13 h) followed by extensive regrowth. As predicted by mechanism-based modeling, the piperacillin plus tobramycin dosage regimens were synergistic and provided ≥5-log10killing with resistance suppression over 8 days in the HFIM. Optimized piperacillin-tobramycin regimens provided significant bacterial killing and suppressed resistance emergence. These regimens appear to be highly promising for effective and early treatment, even in the near-worst-case scenario of ARC.

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Population Pharmacokinetic/Pharmacodynamic Analysis of the Bactericidal Activities of Sutezolid (PNU-100480) and Its Major Metabolite against Intracellular Mycobacterium tuberculosis inEx VivoWhole-Blood Cultures of Patients with Pulmonary Tuberculosis

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01920-13 ◽

2014 ◽

Vol 58 (6) ◽

pp. 3306-3311 ◽

Cited By ~ 20

Author(s):

Tong Zhu ◽

Sven O. Friedrich ◽

Andreas Diacon ◽

Robert S. Wallis

Keyword(s):

Mycobacterium Tuberculosis ◽

Hollow Fiber ◽

Ex Vivo ◽

Parent Compound ◽

Plasma Concentrations ◽

Population Pharmacokinetic ◽

Model Parameters ◽

Data Set ◽

Content Type

ABSTRACTSutezolid (PNU-100480 [U-480]) is an oxazolidinone antimicrobial being developed for the treatment of tuberculosis. An active sulfoxide metabolite (PNU-101603 [U-603]), which reaches concentrations in plasma several times those of the parent, has been reported to drive the killing of extracellularMycobacterium tuberculosisby sutezolid in hollow-fiber culture. However, the relative contributions of the parent and metabolite against intracellularM. tuberculosisin vivoare not fully understood. The relationships between the plasma concentrations of U-480 and U-603 and intracellular whole-blood bactericidal activity (WBA) inex vivocultures were examined using a direct competitive population pharmacokinetic (PK)/pharmacodynamic 4-parameter sigmoid model. The data set included 690 PK determinations and 345 WBA determinations from 50 tuberculosis patients enrolled in a phase 2a sutezolid trial. The model parameters were solved iteratively. The median U-603/U-480 concentration ratio was 7.1 (range, 1 to 28). The apparent 50% inhibitory concentration of U-603 for intracellularM. tuberculosiswas 17-fold greater than that of U-480 (90% confidence interval [CI], 9.9- to 53-fold). Model parameters were used to simulatein vivoactivity after oral dosing with sutezolid at 600 mg twice a day (BID) and 1,200 mg once a day (QD). Divided dosing resulted in greater cumulative activity (−0.269 log10per day; 90% CI, −0.237 to −0.293 log10per day) than single daily dosing (−0.186 log10per day; 90% CI, −0.160 to −0.208 log10per day). U-480 accounted for 84% and 78% of the activity for BID and QD dosing, respectively, despite the higher concentrations of U-603. Killing of intracellularM. tuberculosisby orally administered sutezolid is mainly due to the activity of the parent compound. Taken together with the findings of other studies in the hollow-fiber model, these findings suggest that sutezolid and its metabolite act on different mycobacterial subpopulations.

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The Combination of Rifampin plus Moxifloxacin Is Synergistic for Suppression of Resistance but Antagonistic for Cell Kill of Mycobacterium tuberculosis as Determined in a Hollow-Fiber Infection Model

mBio ◽

10.1128/mbio.00139-10 ◽

2010 ◽

Vol 1 (3) ◽

Cited By ~ 52

Author(s):

G. L. Drusano ◽

Nicole Sgambati ◽

Adam Eichas ◽

David L. Brown ◽

Robert Kulawy ◽

...

Keyword(s):

Mycobacterium Tuberculosis ◽

Combination Therapy ◽

Hollow Fiber ◽

Bacterial Cell ◽

Infection Model ◽

Bacterial Burden ◽

Log Reduction ◽

Significant Difference ◽

Cell Kill ◽

The Impact

ABSTRACTMoxifloxacin is under development for expanded use againstMycobacterium tuberculosis. Rifampin is a mainstay of therapy. We examined the interaction of moxifloxacin plus rifampin for log-phase and nonreplicating persister (NRP) organisms. For this evaluation, we employed our hollow-fiber infection model, in which organisms are exposed to clinically relevant drug concentration-time profiles and the impact on bacterial cell kill and resistant subpopulation amplification is determined. In log phase, resistance emergence was observed in all monotherapy regimens and in no combination therapy regimen. No difference was seen in time to a 3-log reduction in the bacterial burden; there was a significant difference in time to resistance emergence (P= 0.0006). In the NRP experiment, no resistance emergence was seen. There was a significant difference between the monotherapy and combination therapy regimens in time to a 3-log reduction in the bacterial burden (P= 0.042). The combination is efficacious for suppressing resistant organisms but is antagonistic for cell kill.IMPORTANCEM. tuberculosisinfects one-third of the world’s population. Multiresistant organisms have become more frequent, threatening our ability to provide adequate chemotherapy. Moxifloxacin has been seen as an important new agent with the potential to supplant isoniazid or add to the rifampin/isoniazid combination.M. tuberculosisalso exists in different physiological states, including the NRP phenotype. We examined the moxifloxacin/rifampin combination in a newin vitrosystem to allow judgment of how moxifloxacin would interact with rifampin and allow its performance in clinical trials to be placed into perspective. Importantly, the combination suppressed resistance emergence, but at the price of slightly slowing bacterial cell kill. This new combination is a welcome addition to the physician’s armamentarium.

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Developing New Drugs for Mycobacterium tuberculosis Therapy: What Information Do We Get from Preclinical Animal Models?

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01376-20 ◽

2020 ◽

Vol 64 (12) ◽

Author(s):

G. L. Drusano ◽

Brandon Duncanson ◽

C. A. Scanga ◽

S. Kim ◽

S. Schmidt ◽

...

Keyword(s):

Mycobacterium Tuberculosis ◽

Animal Models ◽

Scale Up ◽

New Drugs ◽

Model Systems ◽

Infection Model ◽

New Agents ◽

Content Type ◽

Preclinical Animal Models ◽

The Impact

ABSTRACT Preclinical animal models of infection are employed to develop new agents but also to screen among molecules to rank them. There are often major differences between human pharmacokinetic (PK) profiles and those developed by animal models of infection, and these may lead to substantial differences in efficacy relative to that seen in humans. Linezolid is a repurposed agent employed to great effect for therapy of Mycobacterium tuberculosis. In this study, we used the hollow-fiber infection model (HFIM) to evaluate the impact of different pharmacokinetic profiles of mice and nonhuman primates (NHP) versus humans on bacterial cell kill as well as resistance suppression. We examined both plasma and epithelial lining fluid (ELF) profiles. We examined simulated exposures equivalent to 600 mg and 900 mg daily of linezolid in humans. For both plasma and ELF exposures, the murine PK profile provided estimates of effect that were biased low relative to human and NHP PK profiles. Mathematical modeling identified a linkage between minimum concentrations (Cmin) and bacterial kill and peak concentrations (Cpeak) and resistance suppression, with the latter being supported by a prospective validation study. Finding new agents with novel mechanisms of action against M. tuberculosis is difficult. It would be a tragedy to discard a new agent because of a biased estimate of effect in a preclinical animal system. The HFIM provides a system to benchmark evaluation of new compounds in preclinical animal model systems against human PK effects (species scale-up estimates of PK), to safeguard against unwarranted rejection of promising new agents.

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Activity of Fosfomycin and Amikacin against Fosfomycin-Heteroresistant Escherichia coli Strains in a Hollow-Fiber Infection Model

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02213-20 ◽

2021 ◽

Vol 65 (5) ◽

Author(s):

I. Portillo-Calderón ◽

M. Ortiz-Padilla ◽

B. de Gregorio-Iaria ◽

V. Merino-Bohorquez ◽

J. Blázquez ◽

...

Keyword(s):

Escherichia Coli ◽

Hollow Fiber ◽

Infection Model ◽

Bacterial Burden ◽

Content Type ◽

E Coli ◽

Bacterial Cultures ◽

Agar Dilution ◽

Time Kill ◽

Risk Of Treatment

ABSTRACT We evaluated human-like the efficacy of intravenous doses of fosfomycin of 8 g every 8 h (8 g/Q8h) and of amikacin (15 mg/kg/Q24h) in monotherapy and in combination against six fosfomycin-heteroresistant Escherichia coli isolates using a hollow-fiber infection model (HFIM). Six fosfomycin-heteroresistant E. coli isolates (four with strong mutator phenotype) and the control strain E. coli ATCC 25922 were used. Mutant frequencies for rifampin (100 mg/liter), fosfomycin (50 and 200 mg/liter), and amikacin (32 mg/liter) were determined. Fosfomycin and amikacin MICs were assessed by agar dilution (AD), gradient strip assay (GSA), and broth microdilution (BMD). Fosfomycin and amikacin synergies were studied by checkerboard and time-kill assays at different concentrations. The efficacies of fosfomycin (8 g/Q8h) and amikacin (15 mg/kg/Q24h) alone and in combination were assessed using an HFIM. Five isolates were determined to be resistant to fosfomycin by AD and BMD, but all were determined to be susceptible by GSA. All isolates were determined to be susceptible to amikacin. Antibiotic combinations were synergistic in two isolates, and no antagonism was detected. In time-kill assays, all isolates survived under fosfomycin at 64 mg/liter, although at 307 mg/liter only the normomutators and two hypermutators survived. Four isolates survived under 16 mg/liter amikacin, and none survived at 45 mg/liter. No growth was detected under combination conditions. In HFIM, fosfomycin and amikacin monotherapies failed to sterilize bacterial cultures; however, the combination of fosfomycin and amikacin yielded a rapid eradication. There may be a risk of treatment failure of fosfomycin-heteroresistant E. coli isolates using either amikacin or fosfomycin in monotherapy. These results support that the amikacin-fosfomycin combination can rapidly decrease bacterial burden and prevent the emergence of resistant subpopulations against fosfomycin-heteroresistant strains.

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