Antibacterial effect of seven days exposure to ceftolozane-tazobactam as monotherapy and in combination with fosfomycin or tobramycin against Pseudomonas aeruginosa with ceftolozane-tazobactam MICs at or above 4 mg/l in an in vitro pharmacokinetic model

OBJECTIVES

To use a pre-clinical pharmacokinetic infection model to assess the antibacterial effect of ceftolozane/tazobactam alone or in combination with fosfomycin or tobramycin against Pseudomonas aeruginosa strains with MICs at or higher than the clinical breakpoint (MIC ≥ 4 mg/L).

METHODS

An in vitro model was used to assess changes in bacterial load and population profiles after exposure to mean human serum concentrations of ceftolozane/tazobactam associated with doses of 2 g/1 g q8h, fosfomycin concentrations associated with doses of 8 g q8h or tobramycin at doses of 7 mg/kg q24 h over 168 h.

RESULTS

Simulations of ceftolozane/tazobactam at 2 g/1 g q8h alone produced 3.5-4.5 log reductions in count by 6 h post drug exposure for strains with MIC ≤32 mg/L. The antibacterial effect over the first 24 h was related to ceftolozane/tazobactam MIC. There was subsequent regrowth with most strains to bacterial densities of >106 CFU/mL. Addition of either fosfomycin or tobramycin resulted in suppression of regrowth and in the case of tobramycin more rapid initial bacterial killing up to 6 h. These effects could not be related to either fosfomycin or tobramycin MICs. Changes in population profiles were noted with ceftolozane/tazobactam alone often after 96 h exposure but such changes were suppressed by fosfomycin and almost abolished by the addition of tobramycin.

CONCLUSIONS

The addition of either fosfomycin or tobramycin to ceftolozane/tazobactam at simulated human clinically observed concentrations reduced P. aeruginosa bacterial loads and the risk of resistance to ceftolozane/tazobactam when strains had ceftolozane/tazobactam MIC values at or above the clinical breakpoint.

617. Pharmacodynamics of Ceftolozane-Tazobactam (C/T) as Monotherapy and in Combination with Tobramycin or Fosfomycin Against P.aeruginosa with C/T MICs at or Above 4mg/L

Background

Ceftolozane (C/T) is widely used in clinical practice to treat difficult and/or multidrug resistant Pseudomonas aeruginosa (Pa). However, clinical data is absent on the use of C/T therapy to treat Pa strains with C/T MICs ≥ 4mg/L, that is outside the wild type population. To address this, we simulated 7-day courses of C/T against 8 strains of Pa C/T MICs 4-64mg/L as monotherapy and in combination with tobramycin (T) or fosfomycin (F) using an in vitro pharmacokinetic model.

Methods

A single compartment dilutional in vitro model was used, volume central chamber 360mL, inoculum 106 CFU/mL. Differing drugs t½ were simulated using add back. Pa strain C/T MICs were 4-64mg/L, T 0.25-8mg/L and F 4-1024mg/L. C/T doses of 2-1g, 8h (Cmax 112-32mg/L, t½ 2.5-1h), T doses 7mg/Kg 24h (Cmax 22mg/L, t½ 2.5h) and F doses 4g 8h (Cmax 250mg/L, t½ 2.5h) were simulated for 7 days. Endpoints were changes in bacterial load (log CFU/ml) and population profiles (growth on C/T containing media at MICx4 and MICx8 concentrations).

Results

C/T alone resulted in rapid clearance of all strains after 4-12h exposure, with the antibacterial effect being poorest with strains with the highest C/T MICs. Regrowth occurred with 7/8 strains after 24-48h, counts reaching 6-8 logs by 7 days. Combination of C/T plus T increased the rate of initial clearance and suppressed regrowth with all strains. Combination of C/T plus F did not increase the rate of initial clearance except in the strains with the highest C/T MICs but resulted in suppression of regrowth with final bacterial counts of 3-4 logs at day 7. Changes in C/T population profiles occurred after 7 days exposure with growth on C/T MICx8 containing media in 6/8 strains exposed to C/T alone, but 0/8 strains exposed to C/T plus T and 1/8 strains exposed to C/T plus F.

Conclusion

Combinations of C/T plus T or F resulted in long term suppression of Pa bacterial load and minimised emergence of resistance in Pa strains with C/T MICs on or just above the epidemiological cut off value (MIC 4mg/L-64mg/L).

Disclosures

Alasdair P. MacGowan, MD, GSK: Grant/Research Support|InfectoPharm: Grant/Research Support|Merck: Advisor/Consultant|Shionogi: Advisor/Consultant|Venatorx: Advisor/Consultant.

Cefepime pharmacodynamic targets against Enterobacterales employing neutropenic murine lung infection and in vitro pharmacokinetic models

BACKGROUND

Very limited studies, so far, have been conducted to identify the pharmacodynamic targets of cefepime, a well-established fourth-generation cephalosporin. As a result, conventional targets representing the cephalosporin class are used for cefepime target attainment analysis.

OBJECTIVES

We employed both a neutropenic murine lung infection model and an in vitro pharmacokinetic model (IVPM) to determine cefepime's pharmacodynamic target [percentage of the dosing interval during which unbound drug concentrations remain higher than the MIC (%fT>MIC)] for bacteriostatic and 1 log10 kill effects.

METHODS

Ten strains with cefepime MICs ranging from 0.03 to 16 mg/L were studied in the lung infection. In the IVPM, five cefepime-resistant strains with cefepime/tazobactam (fixed 8 mg/L) MICs ranging from 0.25 to 8 mg/L were included. Through 24 h dose fractionation, both in lung infection and IVPM (in the latter case, tazobactam 8 mg/L continuous infusion was used to protect cefepime), varying cefepime exposures and corresponding pharmacodynamic effect scenarios were generated to identify the pharmacodynamic targets.

RESULTS

Using a non-linear sigmoidal maximum-effect (Emax) model, the cefepime's plasma fT>MIC for 1 log10 kill in lung infection ranged from 17% to 53.7% and a combined exposure-response plot yielded 30%. In the case of IVPM, T>MIC ranged from 6.9% to 75.4% with a mean value of 34.2% for 1 log10 kill.

CONCLUSIONS

Both in vivo and in vitro studies showed that cefepime's pharmacodynamic requirements are lower than generally reported for cephalosporins (50%-70% fT>MIC). The lower requirement for cefepime could be linked with factors such as cefepime's better permeation properties and multiple PBP affinity-driven enhanced bactericidal action.

P43 In vitro activity of cefiderocol and comparators against Gram-negative pathogens: ARTEMIS study in the UK

Objectives

Cefiderocol (CFDC) is a novel siderophore cephalosporin approved in Europe for the treatment of infections caused by aerobic Gram-negative (GN) bacteria in adults with limited treatment options. The aim of the ARTEMIS study was to evaluate the in vitro activity of CFDC and comparators against recent clinical isolates collected across five countries in Europe. Here we report susceptibility data from isolates collected in the UK.

Methods

From January to December 2020, GN clinical isolates were collected from hospitalized patients from all infection sites (excluding the urinary tract). Duplicate isolates of the same species from a single patient were excluded. As a prespecified target, each laboratory collected 75 isolates, with: 20 Klebsiella spp., 20 other Enterobacterales, 20 Pseudomonas aeruginosa and 15 Acinetobacter baumannii isolates expected to be included. CFDC susceptibility testing was conducted using disc diffusion (with 30 μg discs) on Mueller–Hinton agar and Sensititre^™ broth microdilution (BMD) panels [EUMDROXF; centrally tested at International Health Management Associates (IHMA)]. Susceptibility by disc diffusion was reported using zone diameter breakpoints (BPs) of ≥22 mm (or ≥17 mm for A. baumannii isolates, corresponding to MIC values below the pharmacokinetic/pharmacodynamic BPs of ≤2 mg/L). Comparator susceptibility was determined using custom research use only Sensititre^™ BMD panels (CMP2SHIH) according to the EUCAST method for BMD. Antimicrobial susceptibility was interpreted according to EUCAST clinical BPs (v.11 2021).

Results

In total, 517 isolates were collected from nine UK hospitals, of which: 308 (59.6%) were Enterobacterales [including 147 (28.4%) Klebsiella spp.], 148 (28.6%) were P. aeruginosa and 33 (6.4%) were A. baumannii. The most common sites of infection were bloodstream (n = 245; 47.4%), respiratory tract (n = 158; 30.6%) and skin (n = 59; 11.4%). A high percentage of Enterobacterales (90.2%), P. aeruginosa (96.6%) and A. baumannii (96.9%) isolates were susceptible to CFDC by disc diffusion. By central laboratory testing (MIC), 99.0% of Enterobacterales, 99.3% of P. aeruginosa and 93.9% of A. baumannii isolates were susceptible to CFDC. High susceptibility rates (>85%) were also observed for all comparator agents (Table 1). A total of 32/517 (6.2%) isolates were carbapenem resistant, the majority of which (22/32, 68.8%) were susceptible to CFDC by disc diffusion.

Conclusions

Among clinical GN isolates collected from UK hospitals in 2020, a high percentage (98.6%), including carbapenem-resistant isolates, were susceptible to CFDC by BMD. These data support the use of CFDC in patients with GN infections and limited treatment options. The differences identified between EUCAST disc diffusion and BMD using Sensititre^™ panels for CFDC highlight that disc diffusion underestimates Enterobacterales susceptibility to CFDC, which is mainly a result of the area of technical uncertainty (where isolates with MIC of 2 mg/L have a zone diameter of <22 mm and are characterized as resistant). This requires further investigation to explore whether the EUCAST zone diameter BP is optimal for CFDC disc testing.

Evaluation of perturbed iron-homeostasis in a prospective cohort of patients with COVID-19

Background: Marked reductions in serum iron concentrations are commonly induced during the acute phase of infection. This phenomenon, termed hypoferremia of inflammation, leads to inflammatory anemia, but could also have broader pathophysiological implications. In patients with coronavirus disease 2019 (COVID-19), hypoferremia is associated with disease severity and poorer outcomes, although there are few reported cohorts. Methods: In this study, we leverage a well characterised prospective cohort of hospitalised COVID-19 patients and perform a set of analyses focussing on iron and related biomarkers and both acute severity of COVID-19 and longer-term symptomatology. Results: We observed no associations between acute serum iron and long-term outcomes (including fatigue, breathlessness or quality of life); however, lower haemoglobin was associated with poorer quality of life. We also quantified iron homeostasis associated parameters, demonstrating that among 50 circulating mediators of inflammation IL-6 concentrations were strongly associated with serum iron, consistent with its central role in inflammatory control of iron homeostasis. Surprisingly, we observed no association between serum hepcidin and serum iron concentrations. We also observed elevated erythroferrone concentrations in COVID-19 patients with anaemia of inflammation. Conclusions: These results enhance our understanding of the regulation and pathophysiological consequences of disturbed iron homeostasis during SARS-CoV-2 infection.

In vitro pharmacodynamics of omadacycline against Escherichia coli and Acinetobacter baumannii

BACKGROUND

The pharmacodynamics of omadacycline have been extensively studied against Gram-positive pathogens but less information is available for Gram-negative pathogens. We describe the pre-clinical pharmacodynamics of omadacycline against Escherichia coli and Acinetobacter baumannii.

METHODS

An in vitro dilutional pharmacokinetic model was used. Exposure experiments with fAUC/MIC ratios ranging from 0 to 1200 were performed using five strains of E. coli and five strains of A. baumannii. Reduction in bacterial load and changes in population profiles were measured.

RESULTS

The fAUC/MIC targets against E. coli for 24 h static and -1 log reduction in load were 25.3 ± 17.2 and 42.7 ± 32.5, respectively. For A. baumannii the fAUC/MIC for 24 h static effect was 108.1 ± 38.6. Changes in population profiles were observed for E. coli at fAUC/MIC ratios of ≤200 and for A. baumannii up to 1200. MICs were increased 2-32 fold.

CONCLUSIONS

fAUC/MIC targets for A. baumannii are greater than for E.coli and changes in population profiles more likely. E. coli fAUC/MIC targets align with in vivo data and will be useful in determining omadacycline dosing for this pathogen.

Predicting outcomes of COVID-19 from admission biomarkers: a prospective UK cohort study

INTRODUCTION

COVID-19 has an unpredictable clinical course, so prognostic biomarkers would be invaluable when triaging patients on admission to hospital. Many biomarkers have been suggested using large observational datasets but sample timing is crucial to ensure prognostic relevance. The DISCOVER study prospectively recruited patients with COVID-19 admitted to a UK hospital and analysed a panel of putative prognostic biomarkers on the admission blood sample to identify markers of poor outcome.

METHODS

Consecutive patients admitted to hospital with proven or clinicoradiological suspected COVID-19 were consented. Admission bloods were extracted from the clinical laboratory. A panel of biomarkers (interleukin-6 (IL-6), soluble urokinase plasminogen activator receptor (suPAR), Krebs von den Lungen 6, troponin, ferritin, lactate dehydrogenase, B-type natriuretic peptide, procalcitonin) were performed in addition to routinely performed markers (C reactive protein (CRP), neutrophils, lymphocytes, neutrophil:lymphocyte ratio). Age, National Early Warning Score (NEWS2), CURB-65 and radiographic severity score on initial chest radiograph were included as comparators. All biomarkers were tested in logistic regression against a composite outcome of non-invasive ventilation, intensive care admission or death, with area under the curve (AUC) (figures calculated).

RESULTS

187 patients had 28-day outcomes at the time of analysis. CRP (AUC: 0.69, 95% CI: 0.59 to 0.78), lymphocyte count (AUC: 0.62, 95% CI: 0.53 to 0.72) and other routine markers did not predict the primary outcome. IL-6 (AUC: 0.77, 0.65 to 0.88) and suPAR (AUC: 0.81, 0.72 to 0.88) showed some promise, but simple clinical features alone such as NEWS2 score (AUC: 0.70, 0.60 to 0.79) or age (AUC: 0.70, 0.62 to 0.77) performed nearly as well.

DISCUSSION

Admission blood biomarkers have only moderate predictive value for predicting COVID-19 outcomes, while simple clinical features such as age and NEWS2 score outperform many biomarkers. IL-6 and suPAR had the best performance, and further studies should focus on the additive value of these biomarkers to routine care.

The pharmacodynamics of minocycline alone and in combination with rifampicin against Staphylococcus aureus studied in an in vitro pharmacokinetic model of infection

BACKGROUND

Tetracyclines are widely used as oral therapy of MRSA infection, however, the pharmacodynamic underpinning is absent.

OBJECTIVES

We employed an in vitro pharmacokinetic model to study the pharmacodynamics of minocycline alone and in combination with rifampicin.

METHODS

An exposure-ranging design was used to establish fAUC/MIC targets for static, -1 log drop and -2 log drop effects against Staphylococcus aureus for minocycline and in combination with rifampicin. We then simulated 7-10 day human dosing of minocycline and the combination.

RESULTS

The minocycline fAUC/MIC for 24 h static effect and -1 log drop in bacterial load were 12.5 ± 7.1 and 23.3 ± 12.4. fAUC/MIC targets for static and -1 log drop were greater at 48 and 72 h. The addition of simulated free rifampicin associated with dosing 300 mg q12h reduced the 24 h minocycline fAUC/MICs. Simulations performed over 7-10 days exposure indicated that for minocycline standard human doses there was a 1-3 log reduction in viable count and no changes in population profiles. Addition of rifampicin resulted in larger reductions in staphylococcal load but emergence of resistance to rifampicin. There was no resistance to minocycline.

CONCLUSIONS

An fAUC/MIC minocycline target of 12-36 is appropriate for S. aureus. Addition of rifampicin decreases bacterial load but results in emergence of resistance to rifampicin. Unusually, there was no emergence of resistance to minocycline.

Krebs von den Lungen 6 (KL-6) as a marker for disease severity and persistent radiological abnormalities following COVID-19 infection at 12 weeks

INTRODUCTION

Acute presentations of COVID-19 infection vary, ranging from asymptomatic carriage through to severe clinical manifestations including acute respiratory distress syndrome (ARDS). Longer term sequelae of COVID-19 infection includes lung fibrosis in a proportion of patients. Krebs von den Lungen 6 (KL-6) is a mucin like glycoprotein that has been proposed as a marker of pulmonary epithelial cell injury. We sought to determine whether KL-6 was a marker of 1) the severity of acute COVID-19 infection, or 2) the persistence of symptoms/radiological abnormalities at medium term follow up.

METHODS

Prospective single centre observational study.

RESULTS

Convalescent KL-6 levels were available for 93 patients (male 63%, mean age 55.8 years) who attended an 12-week follow up appointment after being admitted to hospital with COVID-19. For 67 patients a baseline KL-6 result was available for comparison. There was no significant correlations between baseline KL-6 and the admission CXR severity score or clinical severity NEWS score. Furthermore, there was no significant difference in the baseline KL-6 level and an initial requirement for oxygen on admission or the severity of acute infection as measured at 28 days. There was no significant difference in the 12-week KL-6 level and the presence or absence of subjective breathlessness but patients with abnormal CT scans at 12 weeks had significantly higher convalescent KL-6 levels compared to the remainder of the cohort (median 1101 IU/ml vs 409 IU/ml).

CONCLUSIONS

The association between high KL-6 levels at 12 weeks and persisting CT abnormalities (GGO/fibrosis), is a finding that requires further exploration. Whether KL-6 may help differentiate those patients with persisting dyspnoea due to complications rather than deconditioning or dysfunctional breathing alone, is an important future research question.

Blood group type A secretors are associated with a higher risk of COVID-19 cardiovascular disease complications

The SARS-CoV-2 virus causes COVID-19, an infection capable of causing severe disease and death but which can also be asymptomatic or oligosymptomatic. We investigated whether ABO blood group or secretor status was associated with COVID-19 severity. We investigated secretor status because expression of ABO glycans on secreted proteins and non-erythroid cells are controlled by a fucosyltransferase (FUT2), and inactivating FUT2 mutations result in a non-secretor phenotype which protects against some viral infections. Data combined from healthcare records and our own laboratory tests (n = 275) of hospitalized SARS-CoV-2 polymerase chain reaction positive patients confirmed higher than expected numbers of blood group A individuals compared to O (RR = 1.24, CI 95% [1.05, 1.47], p = 0.0111). There was also a significant association between group A and COVID-19-related cardiovascular complications (RR = 2.56, CI 95% [1.43, 4.55], p = 0.0011) which is independent of gender. Molecular analysis revealed that group A non-secretors are significantly less likely to be hospitalized than secretors. Testing of convalescent plasma donors, among whom the majority displayed COVID-19 symptoms and only a small minority required hospitalization, group A non-secretors were slightly over-represented. Our findings showed that group A non-secretors are not resistant to infection by SARS-CoV-2, but are more likely to experience a less severe form of associated disease.

Patient outcomes after hospitalisation with COVID-19 and implications for follow-up: results from a prospective UK cohort

The longer-term consequences of SARS-CoV-2 infection are uncertain. Consecutive patients hospitalised with COVID-19 were prospectively recruited to this observational study (n=163). At 8-12 weeks postadmission, survivors were invited to a systematic clinical follow-up. Of 131 participants, 110 attended the follow-up clinic. Most (74%) had persistent symptoms (notably breathlessness and excessive fatigue) and limitations in reported physical ability. However, clinically significant abnormalities in chest radiograph, exercise tests, blood tests and spirometry were less frequent (35%), especially in patients not requiring supplementary oxygen during their acute infection (7%). Results suggest that a holistic approach focusing on rehabilitation and general well-being is paramount.

Antibacterial effect of imipenem/relebactam on aerobic Gram-negative bacilli: in vitro simulations of 7 or 14 day human exposures

OBJECTIVES

We assessed the antibacterial effect of human simulations of dosing with imipenem/relebactam (with or without amikacin) on Enterobacteriaceae or Pseudomonas aeruginosa over 7 or 14 day antibiotic exposures.

METHODS

An in vitro pharmacokinetic model was used to assess changes in bacterial load and population profiles.

RESULTS

Imipenem/relebactam produced an initial >4 log drop in viable counts followed by suppression for 7 days for Enterobacteriaceae whether the strain was WT, produced KPC enzymes or produced an AmpC enzyme with porin loss. Similarly, with the P. aeruginosa strains, there was an initial >4 log clearance over the first 24 h irrespective of whether the strain was WT, hyperexpressed AmpC or had OprD mutation with porin loss. However, with three of four strains there was modest regrowth over the 7 days. There were no changes in imipenem/relebactam MICs over the 7 days. Addition of amikacin in 7 day simulations resulted in more suppression of pseudomonal growth. In 14 day simulations with P. aeruginosa there was regrowth to 8 log10 by 14 days with imipenem/relebactam alone and associated increases in MICs. Addition of amikacin resulted in clearance from the model and prevented changes in population profiles.

CONCLUSIONS

Imipenem/relebactam was highly effective at reducing the bacterial load of Enterobacteriaceae and there was no emergence of resistance. Against P. aeruginosa, the initial bacterial burden was also rapidly reduced, but there was subsequent regrowth, especially after 7 days of exposure. Addition of amikacin increased the clearance of P. aeruginosa and prevented emergence of resistance.

The pharmacodynamics of fosfomycin against Staphylococcus aureus studied in an in vitro model of infection

OBJECTIVES

The pharmacodynamics of intravenous fosfomycin have not been described for Gram-positive pathogens such as Staphylococcus aureus (S. aureus). This paper described the dominant pharmacodynamic index for fosfomycin against S. aureus and its size for antibacterial effect.

METHODS

A single-compartment dilutional in vitro pharmacokinetic model was used to provide fosfomycin exposures against S. aureus, three methicillin-susceptible S. aureus (MSSA), two methicillin-resistant S. aureus (MRSA); fosfomycin MICs were 2 mg/L (one strain), 4 mg/L (one strain), 8 mg/L (two strains) and 16 mg/L (one strain). For all simulations, a fosfomycin half-life of 2.5 hours was modelled. Cmax/MICs from 0-74.8, AUC/MICs from 0-750 and T>MIC 0-100% were simulated. The primary end-points were changes in bacterial load after 24 hours and changes in population profiles after 48 hours.

RESULTS

Log AUC/MIC R² = 0.55 and log Cmax/MIC R² = 0.66 were related to S. aureus log reduction in viable count at 24 hours; T>MIC was poorly related. Cmax/MIC for a 24 hour static, -1 log drop and -2 log drop were 3.0 ± 1.7, 4.6 ± 2.4 and 6.6 ± 3.8, respectively. AUC/MIC for a 24 hour static, -1 log drop and -2 log drop were 26.4 ± 11.8, 42.8 ± 21.8 and 66.6 ± 39.1. Emergence of resistance as indicated by > 2 log growth on MICx8 recovery media was maximal at AUC/MIC ratios of 10-40 and was suppressed at AUC/MIC ratios of ≥ 250.

CONCLUSIONS

The dominant pharmacodynamic index for fosfomycin against S. aureus was Cmax/MIC in terms of reduction of bacterial load and AUC/MIC in terms of suppressing emergence of resistance. AUC/MIC ratios of 20-75 were associated with a -1 log reduction in bacterial load and AUC/MIC of 10-40 maximally increased emergence of resistance.

Antibacterial effect of ceftolozane/tazobactam in combination with amikacin against aerobic Gram-negative bacilli studied in an in vitro pharmacokinetic model of infection

Objectives

To use a pre-clinical infection model to assess the antibacterial effect of human simulations of dosing with ceftolozane/tazobactam (with or without amikacin) or meropenem against Enterobacteriaceae and Pseudomonas aeruginosa.

Methods

An in vitro pharmacokinetic model was used to assess changes in bacterial load and profiles after exposure to mean human serum concentrations over 168 h. Changes in area under the bacterial kill curve (AUBKC; log cfu/mL·h) and growth on 4 × MIC recovery plates were the co-primary outcome measures.

Results

Simulations of ceftolozane/tazobactam at 1 g/0.5 g or 2 g/1 g q8h or meropenem 2 g q8h all produced a >4 log reduction in bacterial load of Escherichia coli. Meropenem had smaller AUBKC values, indicating greater reduction in bacterial load than ceftolozane/tazobactam. Meropenem was also more effective than ceftolozane/tazobactam against Klebsiella pneumoniae strains. All regimens were equally effective in reducing P. aeruginosa bacterial load measured by AUBKC but growth on 4 × MIC recovery plates and changes in population profiles were only seen with meropenem. Addition of amikacin at 15 mg/kg q24h or 7.5 mg/kg q12h to 2 g/1 g of ceftolozane/tazobactam produced greater reductions in bacterial load but generated changes in amikacin population profiles with the 7.5 mg/kg q12h amikacin simulation.

Conclusions

The doses of ceftolozane/tazobactam simulated were highly effective in reducing the bacterial load of E. coli (MIC ≤0.25 mg/L), but less so for K. pneumoniae (MIC 4 mg/L). For both species, meropenem produced an overall greater reduction in pathogen load. Ceftolozane/tazobactam and meropenem were equally effective as monotherapy against P. aeruginosa but emergence of resistance occurred with meropenem. Addition of amikacin to ceftolozane/tazobactam reduced the bacterial load of P. aeruginosa at the expense of emergence of resistance to amikacin.

Experiences and career intentions of general practice registrars from The Netherlands

For some years prospective general practitioners (GPs) from the Netherlands have come to Britain to complete their training. Not all report enjoying their time here, and many leave this country after training. The aim of this study was to examine reasons for coming to Britain, experiences, perceptions and career intentions. The sample consisted of 14 general practice registrars working in their practice year in Southern England. Data were collected through in-depth semistructured interviews and analysed by thematic qualitative analysis. The main reasons for training in this country were easier access, a quicker route to specialization and the quality of training provided. Most had positive professional and personal experiences and saw the British system of training GPs as up to date and supportive of their educational and professional needs. They highlighted some of the positive aspects of the British system, such as the emphasis on teamwork and collaboration with other primary care professionals. They did, however, point out problems and conflicts; for instance, they saw the health care system in Britain as more bureaucratic and as providing unequal access for different groups of the population. Despite their fear of litigation, which they saw as one of the drawbacks for British general practitioners, most looked favourably on the option of staying in or returning to this country if possible. All registrars valued their stay in Britain; however, personal circumstances often dictated a return to Holland. Our findings have implications for manpower planning and recruitment for general practice in both Britain and Holland.

The loneliness of the long-distance manager

Many top managers have been tempted to neglect their own development in the face of massive work agendas. The experiences of 12 senior NHS managers, who were involved in a project designed and implemented by the NHS Training Directorate (NHSTD), bear this out, as Margaret Attwood and colleagues discuss.