Species-dependent hepatic and intestinal metabolism of selective oestrogen receptor degrader LSZ102 by sulphation and glucuronidation.

LSZ102 is an orally bioavailable selective oestrogen receptor degrader in clinical development for the treatment of breast cancer. Preclinical studies showed efficacy in xenograft models on oral dosing. However, oral bioavailability was relatively low in several preclinical species (7-33%), and was associated with first-pass metabolism, particularly intestinal first-pass.To investigate metabolism and first-pass effects, metabolites were analysed in human plasma samples after oral dosing of LSZ102 to patients, rat plasma samples after oral dosing of [14C]LSZ102, and in vitro incubations of [14C]LSZ102 with human and rat hepatocytes and intestinal S9 fractions. The kinetics of human sulfotransferase (SULT) enzymes potentially involved in metabolism of LSZ102 was characterised.Sulphate metabolites were found to be the major components in human plasma, as well as in human hepatocytes and intestinal S9 fractions. Contrastingly, glucuronidation was predominant in rat plasma, hepatocytes and intestinal S9. LSZ102 was found to be metabolised by several human SULTs expressed in liver and intestine. The combined metabolism data in rat and human provide supporting evidence for an extensive intestinal first-pass metabolism effect via sulphation in human but glucuronidation in rat.As LSZ102 is metabolised by a number of different SULTs, drug-drug interactions resulting from the inhibition of one SULT are unlikely.Despite the observed species difference in metabolism, the major human metabolites of LSZ102, sulphate M5, glucuronide M4, and secondary glucuronide/sulphate metabolite M12, have no or weak pharmacological activity and are not considered a toxicity risk as they are phase II conjugative metabolites.

Eltrombopag added to immunosuppression for children with treatment-naïve severe aplastic anaemia.

Acquired severe aplastic anaemia (SAA) has an immune pathogenesis, and immunosuppressive therapy (IST) with anti-thymocyte globulin and cyclosporine is effective therapy. Eltrombopag (EPAG) added to standard IST was associated with higher overall and complete response rates in patients with treatment-naïve SAA compared to a historical IST cohort. We performed a paediatric subgroup analysis of this trial including all patients aged <18 years who received EPAG plus standard IST (n = 40 patients) compared to a historical cohort (n = 87) who received IST alone. Response, relapse, clonal evolution, event-free survival (EFS), and overall survival were assessed. There was no significant difference in either the overall response rate (ORR) or complete response rate at 6 months (ORR 70% in EPAG group, 72% in historical group, P = 0·78). Adults (≥18 years) had a significantly improved ORR of 82% with EPAG compared to 58% historically (P < 0·001). Younger children had lower response rates than did adolescents. The trend towards relapse was higher and EFS significantly lower in children who received EPAG compared to IST alone. Addition of EPAG added to standard IST did not improve outcomes in children with treatment-naïve SAA. EPAG in the paediatric population should not automatically be considered standard of care. Registration: clinicaltrials.gov (NCT01623167).

Comparison of 99mTc-UBI 29-41, 99mTc-ciprofloxacin, 99mTc-ciprofloxacin dithiocarbamate and 111In-biotin for targeting experimental Staphylococcus aureus and Escherichia coli foreign-body infections: an ex-vivo study.

BACKGROUND: Diagnosis of implant-associated infection is challenging. Several radiopharmaceuticals have been described but direct comparisons are limited. Here we compared in vitro and in an animal model 99mTc-UBI, 99mTc-ciprofloxacin, 99mTcN-CiproCS2 and 111In-DTPA-biotin for targeting E. coli (ATCC 25922) and S. aureus (ATCC 43335). METHODS: Stability controls were performed with the labelled radiopharmaceuticals during 6 hours in saline and serum. The in vitro binding to viable or killed bacteria was evaluated at 37 °C and 4 °C. For in vivo studies, Teflon cages were subcutaneously implanted in mice, followed by percutaneous infection. Biodistribution of i.v. injected radiolabelled radiopharmaceuticals were evaluated during 24 h in cages and dissected tissues. RESULTS: Labelling efficiency of all radiopharmaceuticals ranged between 94% and 98%, with high stability both in saline and in human serum. In vitro binding assays displayed a rapid but poor bacterial binding for all tested agents. Similar binding kinetic occurred also with heat-killed and ethanol-killed bacteria. In the tissue cage model, infection was detected at different time points: 99mTc-UBI and 99mTcN-CiproCS2 showed higher infected cage/sterile cage ratio at 24 hours for both E. coli and S. aureus; 99mTc-Ciprofloxacin at 24 hours for both E. coli and at 4 hours for S. aureus; 111In-DTPA-biotin accumulates faster in both E. coli and S. aureus infected cages. CONCLUSIONS: 99mTc-UBI, 99mTcN-CiproCS2 showed poor in vitro binding but good in vivo binding to E. coli only. 111In-DTPA-biotin showed poor in vitro binding but good in vivo binding to S. aureus and poor to E. coli. 99mTc-Ciprofloxacin showed poor in vitro binding but good in vivo binding to all tested bacteria. The mechanism of accumulation in infected sites remains to be elucidated.

Pharmacokinetics, Pharmacodynamics, Tolerability, and Food Effect of Cenerimod, a Selective S1P1 Receptor Modulator in Healthy Subjects.

The pharmacokinetics, pharmacodynamics, tolerability, and food effect of cenerimod, a potent sphingosine-1-phosphate subtype 1 receptor modulator, were investigated in three sub-studies. Two double-blind, placebo-controlled, randomised studies in healthy male subjects were performed. Cenerimod was administered either as single dose (1, 3, 10 or 25 mg; Study 1) or once daily for 35 days (0.5, 1, 2 or 4 mg; Study 2). A two-period cross-over, open-label study was performed to assess the food effect (1 mg, Study 3). The pharmacokinetic profile of cenerimod was characterised by a tmax of 5.0-6.2 h. Terminal half-life after single and multiple doses ranged from 170 to 199 h and 283 to 539 h, respectively. Food had no relevant effect on the pharmacokinetics of cenerimod. A dose-dependent decrease in lymphocyte count was observed after initiation of cenerimod and reached a plateau (maximum change from baseline: -64%) after 20-23 days of treatment. Lymphocyte counts returned to baseline values at end-of-study examination. One serious adverse event of circulatory collapse (25 mg dose group, maximum tolerated dose: 10 mg) and adverse events of mild-to-moderate intensity were reported. Treatment initiation was associated with transient decreases in heart rate and blood pressure at doses >1 and ≥10 mg, respectively.

Bioequivalence of different dose-strength tablets of selexipag, a selective prostacyclin receptor agonist, in a multiple-dose up-titration study.

OBJECTIVE: Selexipag is a novel, oral, selective prostacyclin (PGI2) receptor agonist in clinical development for the treatment of pulmonary arterial hypertension. Film-coated tablets with strength between 200 and 1,600 µg were used. Bioequivalence between 8 x 200 µg and a new 1,600 µg tablet was evaluated at steady state in healthy male subjects. MATERIALS AND METHODS: This was an open-label, 2-treatment, 2-period, crossover, up-titration, phase 1 study. The treatments were selexipag at 1,600 µg b.i.d. for 4.5 days either as 8 x 200 µg tablets (reference: A) or 1 x 1,600 µg tablet (test: B), both preceded by an up-titration phase starting from 400 µg b.i.d. doses, in 200-µg steps every 4th day. Subjects were randomized 1 : 1 to the A-B or B-A sequence. The pharmacokinetics and tolerability of selexipag and its active metabolite, ACT-333679, were investigated. RESULTS: 80 subjects were enrolled in the study: 65 subjects completed the study according to protocol, and 15 subjects withdrew from the study. The most frequent adverse events (AEs) were headache (86%), myalgia (73%), and jaw pain (73%). There was no difference in nature and overall frequency of AEs between the two treatments. Steady state was attained within 3 days of the selexipag 1,600 λg b.i.d. TREATMENTS: The 90% confidence intervals (CIs) of the geometric mean ratio (B/A) at steady state for AUCτ and Cmax,ss were within (0.80, 1.25) bioequivalence interval: (0.92, 1.06) and (0.95, 1.14), respectively, for selexipag and (0.95, 1.06) and (0.94, 1.07), respectively, for the active metabolite, ACT-333679. CONCLUSIONS: Bioequivalence was demonstrated between 8 x 200 µg and 1 x 1,600 µg selexipag at steady state.

Cadazolid, a novel antibiotic with potent activity against Clostridium difficile: safety, tolerability and pharmacokinetics in healthy subjects following single and multiple oral doses.

OBJECTIVES: Current treatment options for Clostridium difficile-associated diarrhoea (CDAD) leave a high unmet medical need for new therapies. Cadazolid is a new antibiotic in development for the treatment of CDAD. The objectives of this study were to evaluate its tolerability and pharmacokinetics following single ascending doses (AC-061-101) and multiple ascending doses (AC-061-102). METHODS: Single and multiple (twice daily for 10 days) oral doses of cadazolid between 30 mg and 3000 mg, or placebo, were tested in a total of 64 healthy male subjects. Safety assessments were conducted at regular intervals. Blood, urine and faeces were sampled, and cadazolid concentrations were measured. RESULTS: Cadazolid was well tolerated up to 3000 mg given twice daily for 10 days. The most common adverse event was headache, with no observed relationship between dose or treatment duration and adverse events. Plasma concentrations of cadazolid were low. No plasma concentrations >3.3 ng/mL were observed after single doses or >6.9 ng/mL after 10 days of multiple doses. Food increased the mean C(max) from 0.73 to 1.87 ng/mL and mean AUC(0-t) from 3.13 to 15.69 ng ·h/mL after a single 300 mg dose. The increase in systemic exposure to cadazolid across doses was less than dose-proportional. The mean cumulative faecal recovery was 81.0%-93.5%. Urinary recovery of unchanged compound was <0.015%. CONCLUSIONS: Cadazolid was well tolerated and its systemic exposure was low. The majority of compound was recovered unchanged in the faeces, thus resulting in high concentrations at the site of action (colon).

In vitro activity of gallium maltolate against Staphylococci in logarithmic, stationary, and biofilm growth phases: comparison of conventional and calorimetric susceptibility testing methods.

Ga(3+) is a semimetal element that competes for the iron-binding sites of transporters and enzymes. We investigated the activity of gallium maltolate (GaM), an organic gallium salt with high solubility, against laboratory and clinical strains of methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-resistant S. aureus (MRSA), methicillin-susceptible Staphylococcus epidermidis (MSSE), and methicillin-resistant S. epidermidis (MRSE) in logarithmic or stationary phase and in biofilms. The MICs of GaM were higher for S. aureus (375 to 2000 microg/ml) than S. epidermidis (94 to 200 microg/ml). Minimal biofilm inhibitory concentrations were 3,000 to >or=6,000 microg/ml (S. aureus) and 94 to 3,000 microg/ml (S. epidermidis). In time-kill studies, GaM exhibited a slow and dose-dependent killing, with maximal action at 24 h against S. aureus of 1.9 log(10) CFU/ml (MSSA) and 3.3 log(10) CFU/ml (MRSA) at 3x MIC and 2.9 log(10) CFU/ml (MSSE) and 4.0 log(10) CFU/ml (MRSE) against S. epidermidis at 10x MIC. In calorimetric studies, growth-related heat production was inhibited by GaM at subinhibitory concentrations; and the minimal heat inhibition concentrations were 188 to 4,500 microg/ml (MSSA), 94 to 1,500 microg/ml (MRSA), and 94 to 375 microg/ml (MSSE and MRSE), which correlated well with the MICs. Thus, calorimetry was a fast, accurate, and simple method useful for investigation of antimicrobial activity at subinhibitory concentrations. In conclusion, GaM exhibited activity against staphylococci in different growth phases, including in stationary phase and biofilms, but high concentrations were required. These data support the potential topical use of GaM, including its use for the treatment of wound infections, MRSA decolonization, and coating of implants.

Linezolid alone or combined with rifampin against methicillin-resistant Staphylococcus aureus in experimental foreign-body infection.

We investigated the activity of linezolid, alone and in combination with rifampin (rifampicin), against a methicillin-resistant Staphylococcus aureus (MRSA) strain in vitro and in a guinea pig model of foreign-body infection. The MIC, minimal bactericidal concentration (MBC) in logarithmic phase, and MBC in stationary growth phase were 2.5, >20, and >20 microg/ml, respectively, for linezolid; 0.01, 0.08, and 2.5 microg/ml, respectively, for rifampin; and 0.16, 0.63, >20 microg/ml, respectively, for levofloxacin. In time-kill studies, bacterial regrowth and the development of rifampin resistance were observed after 24 h with rifampin alone at 1x or 4x the MIC and were prevented by the addition of linezolid. After the administration of single intraperitoneal doses of 25, 50, and 75 mg/kg of body weight, linezolid peak concentrations of 6.8, 12.7, and 18.1 microg/ml, respectively, were achieved in sterile cage fluid at approximately 3 h. The linezolid concentration remained above the MIC of the test organism for 12 h with all doses. Antimicrobial treatments of animals with cage implant infections were given twice daily for 4 days. Linezolid alone at 25, 50, and 75 mg/kg reduced the planktonic bacteria in cage fluid during treatment by 1.2 to 1.7 log(10) CFU/ml; only linezolid at 75 mg/kg prevented bacterial regrowth 5 days after the end of treatment. Linezolid used in combination with rifampin (12.5 mg/kg) was more effective than linezolid used as monotherapy, reducing the planktonic bacteria by >or=3 log(10) CFU (P < 0.05). Efficacy in the eradication of cage-associated infection was achieved only when linezolid was combined with rifampin, with cure rates being between 50% and 60%, whereas the levofloxacin-rifampin combination demonstrated the highest cure rate (91%) against the strain tested. The linezolid-rifampin combination is a treatment option for implant-associated infections caused by quinolone-resistant MRSA.

Efficacy of daptomycin in implant-associated infection due to methicillin-resistant Staphylococcus aureus: importance of combination with rifampin.

Limited treatment options are available for implant-associated infections caused by methicillin (meticillin)-resistant Staphylococcus aureus (MRSA). We compared the activity of daptomycin (alone and with rifampin [rifampicin]) with the activities of other antimicrobial regimens against MRSA ATCC 43300 in the guinea pig foreign-body infection model. The daptomycin MIC and the minimum bactericidal concentration in logarithmic phase and stationary growth phase of MRSA were 0.625, 0.625, and 20 microg/ml, respectively. In time-kill studies, daptomycin showed rapid and concentration-dependent killing of MRSA in stationary growth phase. At concentrations above 20 microg/ml, daptomycin reduced the counts by >3 log(10) CFU/ml in 2 to 4 h. In sterile cage fluid, daptomycin peak concentrations of 23.1, 46.3, and 53.7 microg/ml were reached 4 to 6 h after the administration of single intraperitoneal doses of 20, 30, and 40 mg/kg of body weight, respectively. In treatment studies, daptomycin alone reduced the planktonic MRSA counts by 0.3 log(10) CFU/ml, whereas in combination with rifampin, a reduction in the counts of >6 log(10) CFU/ml was observed. Vancomycin and daptomycin (at both doses) were unable to cure any cage-associated infection when they were given as monotherapy, whereas rifampin alone cured the infections in 33% of the cages. In combination with rifampin, daptomycin showed cure rates of 25% (at 20 mg/kg) and 67% (at 30 mg/kg), vancomycin showed a cure rate of 8%, linezolid showed a cure rate of 0%, and levofloxacin showed a cure rate of 58%. In addition, daptomycin at a high dose (30 mg/kg) completely prevented the emergence of rifampin resistance in planktonic and adherent MRSA cells. Daptomycin at a high dose, corresponding to 6 mg/kg in humans, in combination with rifampin showed the highest activity against planktonic and adherent MRSA. Daptomycin plus rifampin is a promising treatment option for implant-associated MRSA infections.

Performance of microcalorimetry for early detection of methicillin resistance in clinical isolates of Staphylococcus aureus.

We describe a calorimetric assay for the detection of methicillin-resistant Staphylococcus aureus (MRSA) within 5 h. Microbial heat was calculated in culture with and without cefoxitin. Among 30 genetically distinct clinical isolates, 19/20 MRSA (95%) and 10/10 methicillin-susceptible Staphylococcus aureus (100%) were correctly identified. Microcalorimetry may be useful for rapid MRSA screening.

Evaluation of a Novel Tc-99m Labelled Vitamin B12 Derivative for Targeting Escherichia coli and Staphylococcus aureus In Vitro and in an Experimental Foreign-Body Infection Model.

PURPOSE: Vitamin B12 (cyanocobalamin, Cbl) is accumulated by rapidly replicating prokaryotic and eukaryotic cells. We investigated the potential of a Tc-99m labelled Cbl derivative ([(99m)Tc]PAMA(4)-Cbl) for targeting infections caused by Escherichia coli and Staphylococcus aureus. In vitro binding assays were followed by biodistribution studies in a mouse model of foreign body infection. PROCEDURES: E. coli (ATCC 25922) and S. aureus (ATCC 43335) were used as test strains. [(57)Co]Cbl, [(67)Ga]citrate and [(99m)Tc]DTPA served as reference compounds. The in vitro competitive binding of [(57)Co]Cbl or [(99m)Tc]PAMA(4)-Cbl, and unlabeled Cbl, to viable or killed bacteria, was evaluated at 37 and 4 °C. A cage mouse model of infection was used for biodistribution of intravenous [(57)Co]Cbl and [(99m)Tc]PAMA(4)-Cbl in cage and dissected tissues of infected and non-infected mice. RESULTS: Maximum binding (mean ± SD) of [(57)Co]Cbl to viable E. coli was 81.7 ± 2.6 % and to S. aureus 34.0 ± 6.7 %, at 37 °C; no binding occurred to heat-killed bacteria. Binding to both test strains was displaced by 100- to 1000-fold excess of unlabeled Cbl. The in vitro binding of [(99m)Tc]PAMA(4)-Cbl was 100-fold and 3-fold lower than the one of [(57)Co]Cbl for E. coli and S. aureus, respectively. In vivo, [(99m)Tc]PAMA(4)-Cbl showed peak percentage of injected dose (% ID) values between 1.33 and 2.3, at 30 min post-injection (p.i.). Significantly higher retention occurred in cage fluids infected with S. aureus at 4 h and with E. coli at 8 h p.i. than in non-infected animals. Accumulation into infected cages was also higher than the one of [(99m)Tc]DTPA, which showed similar biodistribution in infected and sterile mice. [(57)Co]Cbl gradually accumulated in cages with peaks % ID between 3.58 and 4.83 % achieved from 24 to 48 h. Discrimination for infection occurred only in E. coli-infected mice, at 72 h p.i. [(67)Ga]citrate, which showed a gradual accumulation into cage fluids during 12 h, was discriminative for infection from 48 to 72 h p.i. (P < 0.05). CONCLUSION: Cbl displayed rapid and specific in vitro binding to test strains. [(99m)Tc]PAMA(4)-Cbl was rapidly cleared from most tissues and discriminated between sterile and infected cages, being a promising candidate for imaging infections in humans.

A new reversible and potent P2Y12 receptor antagonist (ACT-246475): tolerability, pharmacokinetics, and pharmacodynamics in a first-in-man trial.

BACKGROUND AND OBJECTIVES: ACT-246475 is a new reversible, selective, and potent antagonist of the platelet P2Y12 receptor. This study was a first-in-man trial investigating the tolerability, pharmacokinetics, and pharmacodynamics of single oral doses of ACT-246475 and its di-ester prodrug (ACT-281959) in healthy males. METHODS: The study had a double-blind, randomized, ascending single-dose design with an oral formulation F1 (i.e., ACT-281959 or placebo) (Part I) and an open-label, randomized, 3-period, crossover design comparing exploratory formulations of ACT-281959 (F2) 70 mg and ACT-246475 (dF) 50 mg to F1 70 mg (Part II). In Part I, doses up to 1,000 mg were tested in 40 healthy subjects. Nine healthy subjects were enrolled in Part II. Standard safety parameters, inhibition of platelet aggregation, and ACT-246475 plasma concentrations were measured. Non-compartmental pharmacokinetic analysis was performed. RESULTS: All doses and formulations were well tolerated. The most frequent adverse event was headache, whereas no events of bleeding or dyspnea were reported. In Part I, ACT-246475 area under the plasma concentration-time curve (AUC) increased dose-proportionally whereas maximum plasma concentration (C max) was less than dose-proportional. The highest C max [geometric mean (95 % CI)] at 1,000 mg was 13.8 (9.7, 19.5) pmol/mL at 4.5 h post-dose, terminal half-life (t ½) was ~10 h. ACT-246475 C max and AUC0-∞ ratios of geometric means (90 % CI) using F1 as reference, for F2 were 8.5 (5.42, 13.35) and 3.4 (2.40, 4.82), respectively, and for dF 2.2 (1.42, 3.49) and 1.5 (1.07, 2.16), respectively. Mean peak platelet inhibition was 31.0 % after F1 (1,000 mg) and 47.8 % after F2. CONCLUSIONS: Oral doses of ACT-281959 and ACT-246475 were well tolerated. Platelet inhibition correlated with ACT-246475 exposure. Exploratory formulations enhanced the bioavailability and antiplatelet effect of ACT-246475.

Setipiprant, a selective oral antagonist of human CRTH2: relative bioavailability of a capsule and a tablet formulation in healthy female and male subjects.

BACKGROUND: CRTH2 is a prostaglandin D2 receptor that plays an important role in allergic inflammation. Setipiprant is a potent CRTH2 antagonist under development for the treatment of allergic diseases. OBJECTIVE: The aim of this study was to evaluate the tolerability and pharmacokinetics of a single oral dose of a setipiprant capsule (reference) and a tablet formulation. METHODS: This was an open-label, 2-period, 2-way crossover, randomized study in which 20 healthy women and men (1:1 ratio) received either 2 250-mg capsules or a 500-mg tablet of setipiprant. Subjects were between 18 and 45 years old, with a body mass index of 18.0 to 28.0 kg/m(2). Differences in pharmacokinetics of setipiprant formulations were explored overall and by sex. RESULTS: All subjects completed the study. Both formulations were well tolerated, with headache the most frequently reported adverse event (25% of subjects), followed by flatulence (15%) and somnolence and fatigue (10%). The adverse event profile in men and women and between formulations was similar. The ratios of geometric means for Cmax (0.94; 95% CI, 0.79-1.12) and AUC0-∞ (1.01; 95% CI, 0.92-1.12) were mostly within the limits of 0.80 to 1.25. When corrected for weight, the differences observed between sexes, within each treatment, for Cmax (capsules: 1.01; 95% CI, 0.71-1.44; tablet: 0.89; 95% CI, 0.62-1.26) and AUC0-∞ (capsules: 1.12; 95% CI, 0.86-1.47; tablet: 0.96; 95% CI, 0.73-1.25) were minor. CONCLUSION: Both the setipiprant formulations were well tolerated. Setipiprant pharmacokinetics were similar between formulations, overall, and between sexes. The new tablet formulation may constitute a valid alternative to the capsule formulation for later clinical development phases. ClinicalTrials.gov identifier: NCT01877629.

Activity of dalbavancin, alone and in combination with rifampicin, against meticillin-resistant Staphylococcus aureus in a foreign-body infection model.

The activity of dalbavancin, a representative of the lipoglycopeptide antibiotics, alone and in combination with rifampicin, was investigated against meticillin-resistant Staphylococcus aureus (MRSA) in a foreign-body infection model in guinea pigs. The MIC, MBC and time-kill profile of dalbavancin were determined for MRSA ATCC 43300 in the logarithmic (MBC(log)) and stationary (MBC(stat)) growth phases. The pharmacokinetic profile of dalbavancin was determined in sterile cage fluid in guinea pigs. The activity of intraperitoneal dalbavancin (40, 60 or 80 mg/kg as a single dose), rifampicin (12.5 mg/kg/12 h for 4 days) and their combination was assessed against planktonic and biofilm MRSA. The MIC of dalbavancin was 0.078 mg/L; MBC(log) and MBC(stat) were both >128× MIC. In time-kill studies, bacterial reduction of 3log(10)CFU/mL was achieved after 48 h at ≥32× MIC (logarithmic growth) and at ≥1× MIC (stationary growth). Dalbavancin was neither synergistic nor antagonistic with rifampicin, and prevented the emergence of rifampicin resistance in vitro. The half-life of dalbavancin in cage fluid was 35.8-45.4 h and the concentration remained above the MIC of MRSA during 7 days after a single dose. Dalbavancin reduced planktonic MRSA in cage fluid at high dose (60 mg/kg and 80 mg/kg) but failed to eradicate biofilm MRSA from cages. In combination with rifampicin, dalbavancin at 80 mg/kg cured 36% of infected cages, and emergence of rifampicin resistance was completely prevented. Dalbavancin at 80 mg/kg and in combination with rifampicin eradicated approximately one-third of cage-associated MRSA infections and prevented emergence of rifampicin resistance.