Antimicrobial usage in farm animal practices in the UK: A mixed-methods approach

Antimicrobial resistance (AMR) is a growing One Health problem. Monitoring antimicrobial usage in farm animals is crucial for tackling AMR. A cohort study using the electronic clinical records during 2019 from 23 farm animal veterinary practices across the UK belonging to two corporate groups, with a range of 2-14 veterinarians per practice, estimated the usage of antimicrobials and highest priority critically important antimicrobials (HP-CIAs). Risk factors for using HP-CIAs were evaluated using hierarchical mixed-effects logistic regression modelling with practice ID and farm ID added as random effects. Using a qualitative approach, veterinarians from one of the participating practice groups were recruited for a qualitative study to explore the barriers and facilitators in relation to antimicrobial use. Semi-structured interviews were conducted with participants and analysed thematically. During the year 2019, 98,824 antimicrobial prescribing events overall were recorded from the treatment records of the 23 participating practices. The median count of antimicrobial events per practice was 3226 (range 263-22,159). There were 17,111/98,824 (17.3%) HP-CIAs events overall, with a median of 15.4% at practice level (range 4.8-22.1%). Penicillins were the most frequently used antimicrobials 29,539/98,824 (29.9%) followed by tetracyclines 19,015/98,824 (19.2%). HP-CIA use was strongly clustered, with more clustering seen at the farm level (intraclass correlation coefficient (ICC)= 0.56) than at the practice level (ICC= 0.32). Country, route of administration, season and practice type were significantly associated with the usage of HP-CIAs. Four main themes were identified from the analysis of the veterinarians' interviews: pressure from the industry, drug-related factors, knowledge level of veterinarians and clinical factors. Supermarket contracts and farm assurance schemes were facilitators for reducing antimicrobial use and the use of HP-CIAs. Ease of administration and the withdrawal period of the antimicrobials influenced veterinarians' choice of antimicrobials. The clinical condition and clinical signs presented on farm were reported to influence participating veterinarians' prescribing decision. Participants showed a good understanding of AMR, responsible use of antimicrobials and the term 'critically important antimicrobials'. In conclusion, integrating the quantitative and qualitative findings can inform policymaking on antimicrobials stewardship in farm practice. By estimating the relative levels of clustering of antimicrobial use at the practice and farm level, as well as identifying major risk factors for using HP-CIAs, more targeted interventions can be designed to promote responsible antimicrobial use in farm practice. Furthermore, better understanding the industry pressures on farms to reduce antimicrobials usage could reduce the barriers for responsible antimicrobial use by veterinarians.

Selecting, assessing and interpreting measures of function for patients with severe hip pathology: The need for caution

INTRODUCTION

It is not always possible to use a combination of patient-reported outcome measures (PROMs), performance tests and clinician-administrated measures to assess physical function prior to hip surgery. We hypothesised that there would be low correlations between these three types of measure and that they would be associated with different patients' characteristics.

MATERIALS AND METHODS

We conducted a cross-sectional analysis of the preoperative information of 125 participants listed for hip replacement. The WOMAC-function subscale, Harris Hip Score (HHS) and walk, step and balance tests were assessed by questionnaire or during a clinic visit. Participant's socio-demographics and medical characteristics were also collected. Correlations between functional measures were investigated with correlation coefficients. Regression models were used to test the association between the patient's characteristics and each of the three types of functional measures.

RESULTS

None of the correlations between the PROM, clinician-administrated measure and performance tests were very high (<0.90). Associations between patient's characteristics and functional scores varied by type of measure. Psychological status was associated with the PROM (P-value<0.0001) but not with the other measures. Age was associated with the performance test measures (P-value ranging from ≤0.01 to <0.0001) but not with the PROM. The clinician-administered measure was not associated with age or psychological status.

DISCUSSION

Substantial discrepancies exist when assessing hip function using a PROM, functional test or a clinician-administered test. Moreover, these assessment methods are influenced differently by patient's characteristics. Clinicians should supplement their pre-surgery assessment of function with patient-reported measure to include the patient's perspective.

LEVEL OF EVIDENCE

III, observational cross-sectional study.

Farming on the edge: farmer attitudes to bovine tuberculosis in newly endemic areas

Defra's recent strategy to eradicate bovine tuberculosis (bTB) establishes three spatial zones: high-risk areas (HRAs) and low-risk areas, and an area referred to as 'the edge', which marks the areas where infection is spreading outwards from the HRA. Little is known about farmers in the edge area, their attitudes towards bTB and their farming practices. This paper examines farmers' practices and attitudes towards bTB in standardised epidemiologically defined areas. A survey was developed to collect data on farmer attitudes, behaviours, practices and environmental conditions as part of an interdisciplinary analysis of bTB risk factors. Survey items were developed from a literature review and focus groups with vets and farmers in different locations within the edge area. A case-control sampling framework was adopted with farms sampled from areas identified as recently endemic for bTB. 347 farmers participated in the survey including 117 with bTB, representing a 70per cent response rate. Results show that farmers believe they are unable to do anything about bTB but are keen for the government intervention to help control the spread of bTB.

Assessing the impact of diagnosis and the related supportive care needs in patients with cutaneous melanoma

PURPOSE

Despite the large number of people affected by melanoma, little is known about the specific needs of melanoma patients. Understanding the effects of melanoma diagnosis and the specific supportive care needs of this group of patients is a necessary step towards provision of effective psychosocial care.

METHODS

Semi-structured interviews were carried out with 15 patients with malignant melanoma of the skin. The sample size, which was purposive, included 8 females and 7 males from 27 to 78 years old. Data were analysed using the NVIVO 8 software and principles of thematic analysis.

RESULTS

Four major areas were identified: (a) Emotional effects due to body image, fear of the sun and uncertainty for the future; (b) Effects on Relationships, with some patients in need of more support than others from family and work colleagues; (c) Functional effects due to on-going symptoms such as pain and lymphedema; and (d) Health System and Information Needs, around the clarity, quality and timing of the information received from the health care professionals.

CONCLUSIONS

The findings suggest that we often fail to pick up melanoma patients' health and psychosocial needs and fail to refer them appropriately, rather than the services not being available. Interventions should focus on patient and carer education about melanoma and sun protection, psychosocial support and effective information giving. Patient-reported outcome measures should routinely be collected to identify issues of specific concerns to the patients and directing them to the right services based on their individual needs.

Prevalence and correlates of unmet supportive care needs in patients with resected invasive cutaneous melanoma

BACKGROUND

Knowledge about supportive care needs in patients with cutaneous invasive melanoma is scarce. We examined the unmet needs of melanoma patients treated with surgery and factors associated with these needs to assist health professionals identify areas needing clinical attention.

PATIENTS AND METHODS

Cross-sectional multisite survey of UK patients ascertained 3 months to 5 years after complete resection of stage I-III cutaneous melanoma. Participants completed the following validated questionnaires: Supportive Care Needs Survey (SCNS-SF34 with melanoma module), Hospital Anxiety and Depression Scale and 51-item Functional Assessment of Cancer Therapy-Melanoma quality-of-life scale.

RESULTS

A total of 472 participants were recruited [319 (67%) clinical stage I-II). Mean age was 60 years (standard deviation = 14) and 255 (54%) were female. One hundred and twenty-three (27%) participants reported at least one unmet need (mostly 'low' level). The most frequently reported unmet needs were fears of cancer returning (n = 138, 29%), uncertainty about the future (n = 119, 25%), lack of information about risk of recurrence (n = 112, 24%) and about possible outcomes if melanoma were to spread (n = 91, 20%). One hundred and thirty-eight (29%) participants reported anxiety and 51 (11%) depression at clinical or subclinical levels. Patients with nodal disease had a significantly higher level of unmet supportive care needs (P < 0.001) as did patients with anxiety or depression (P < 0.001). Key correlates of the total SCNS-SF34 score for unmet supportive care needs were younger age (odds ratio, OR = 2.23, P < 0.001) and leaving school early (OR = 4.85, P < 0.001), while better emotional (OR = 0.89, P < 0.001) and social well-being (OR = 0.91, P < 0.001) were linked with fewer unmet needs. Neither patients' sex nor tumour thickness was associated with unmet needs.

CONCLUSIONS

Around a quarter of melanoma patients may have unmet support needs in the mid to long term after primary treatment. In particular, patients who are younger, less educated, distressed or socially isolated could benefit from more support.

Mapping patients' experiences from initial change in health to cancer diagnosis: a qualitative exploration of patient and system factors mediating this process

Delays in the diagnosis of cancer are common, and they are attributed to both patient and healthcare system factors. Minimizing such delays and improving early detection rates is a key goal of the new cancer reform strategy in England, in light of recent data showing that survival rates in the UK are low. The aim of this study was to explore the pathway from initial persistent change in health to diagnosis of cancer in a sample of patients from seven diagnostic groups in the UK and the factors mediating this process. Qualitative interviews with patients diagnosed with cancer were carried out. Seventy-five cancer patients discussed their pre-diagnosis experience as part of a broader exploration of their symptom experience for a larger study. Data were analysed by using content analysis and chart events. A broader range of mediating factors affecting and extending the patient pathway to diagnosis were reported in relation to lung, gastrointestinal and head and neck cancers and lymphoma, compared with breast, gynaecological and brain cancer patients. Many of the mediating factors were patient-related (e.g. misattribution of symptoms to common ailments, underestimation of the seriousness of the symptoms, self-medication or monitoring of symptoms, etc.). Primary care practitioner-factors were also prominent, including the exploration of firstly more common possibilities for treating the presenting symptoms without follow-up of persisting symptoms. Public health education about common cancer signs and symptoms, educational approaches in primary care to improve early diagnoses of cancer and updated guidelines for referral of suspected cancers should be enhanced before we can see any improvements in survival rates from cancer in the UK.

Preclinical pharmacokinetics and metabolism of a novel prototype DNA-PK inhibitor NU7026

In this study we investigated the in vitro time dependence of radiosensitisation, pharmacokinetics and metabolism of NU7026, a novel inhibitor of the DNA repair enzyme DNA-dependent protein kinase (DNA-PK). At a dose of 10 μM, which is nontoxic to cells per se, a minimum NU7026 exposure of 4 h in combination with 3 Gy radiation is required for a significant radiosensitisation effect in CH1 human ovarian cancer cells. Following intravenous administration to mice at 5 mg kg⁻¹, NU7026 underwent rapid plasma clearance (0.108 l h⁻¹) and this was largely attributed to extensive metabolism. Bioavailability following interperitoneal (i.p.) and p.o. administration at 20 mg kg⁻¹ was 20 and 15%, respectively. Investigation of NU7026 metabolism profiles in plasma and urine indicated that the compound undergoes multiple hydroxylations. A glucuronide conjugate of a bis-hydroxylated metabolite represented the major excretion product in urine. Identification of the major oxidation site as C-2 of the morpholine ring was confirmed by the fact that the plasma clearance of NU7107 (an analogue of NU7026 methylated at C-2 and C-6 of the morpholine ring) was four-fold slower than that of NU7026. The pharmacokinetic simulations performed predict that NU7026 will have to be administered four times per day at 100 mg kg⁻¹ i.p. in order to obtain the drug exposure required for radiosensitisation.

Pharmacokinetic/pharmacodynamic study of ZD9331, a nonpolyglutamatable inhibitor of thymidylate synthase, in a murine model following two curative administration schedules

ZD9331 is a nonpolyglutamatable antifolate inhibitor of thymidylate synthase currently in clinical development. This enzyme is crucial for DNA synthesis and catalyzes the reductive methylation of dUMP to form thymidylate, which is subsequently converted to dTTP. The pharmacokinetics of two curative antitumor doses of ZD9331 administered by either a single i.p. bolus injection (50 mg/kg) or by 24-h s.c. infusion (3 mg/kg) have been measured in a thymidine salvage-incompetent murine lymphoma model (L5178Y) using a sensitive and specific ELISA. To gain an understanding of the relationship between the pharmacokinetics of ZD9331 and antitumor activity perturbations in tumor, dTTP and dUMP concentrations were also determined. After bolus administration, ZD9331 was eliminated from plasma and tissues relatively rapidly, with terminal elimination (lambda(z) 0-24 h) of 4-6 h. Liver concentrations were 8-fold higher than those measured in the plasma. Kidney and lymphoma drug concentrations were similar to those of plasma, although there was evidence of a slower overall elimination of drug at later time points. Steady-state concentrations of ZD9331 were obtained 4-5 h after the start of the 24 h s.c. infusion. At the end of infusion, elimination rates were similar for plasma and tissues (approximately 3.5 h) but appeared to be slower in the tumor at later time points. Liver concentrations were approximately 4-fold higher, and kidney and tumor concentrations were similar to those in the circulation. Depletion of dTTP and elevation in dUMP in the tumor were consistent with inhibition of thymidylate synthase after both administration schedules, although the time for which dTTP was decreased was longer (approximately 24 h) for the infusional route than for the bolus injection (<16 h). The results suggest that antitumor activity is dependent on attaining adequate drug concentrations to affect dTTP pools as well as on the duration of effective drug levels.

Leucovorin rescue from raltitrexed (tomudex)-induced antiproliferative effects: in vitro cell line and in vivo mouse studies

Raltitrexed (RTX) is an antifolate thymidylate synthase (TS) inhibitor that is effective for the treatment of advanced colorectal cancer and other solid tumors. However, a small minority of patients receiving RTX monotherapy will experience grade III/IV gastrointestinal toxicity that can be life-threatening, particularly if copresenting with neutropenia. Lack of vigilance in recognition and treatment of symptoms of toxicity or violations of protocol have led to treatment-related deaths in some hospitals. The safety of RTX could be improved if an effective rescue agent was available. Leucovorin (LV) is a reduced folate cofactor that competes with RTX for transport and polyglutamation in both tumor and normal tissues and thus has potential as a rescue agent. In vitro cell studies are presented suggesting that the growth-inhibitory, and potentially cytotoxic, effects of RTX on populations of viable cells can be reversed by the delayed administration of LV. The mechanisms involved are inhibition of further drug uptake and polyglutamation and a redistribution and/or reduction in the concentration of preformed raltitrexed polyglutamates. A more clinically relevant in vivo mouse model was used to test the hypothesis further. BALB/c mice treated with 100 mg/kg/day x 4 days of RTX were used as a model for gastrointestinal and bone marrow toxicity. LV (200 mg/kg), which was given after the onset of severe weight loss and diarrhea (twice daily, days 5-7), prevented further weight loss and induced earlier recovery. This was accompanied by improvement in the histological appearance of the intestine (day 7) and the concentration of neutrophils and platelets in the blood (day 9). BALB/c mice could not tolerate 100 mg/kg daily x 5 days unless LV (200 mg/kg twice daily) was given on days 6-8. Measurement of RTX (polyglutamates) by RIA after 100 mg/kg RTX daily (days 1-4) showed less drug in plasma (3-4-fold), liver (8-11-fold), kidney (3-4-fold), and small intestinal epithelium (3-4-fold) on day 7 in LV-treated mice (100 or 200 mg/kg twice daily) compared with controls. A single injection of 100 mg/kg RTX (day 1) gave plasma levels of 3-4 pmol/ml on day 4 that are more clinically relevant. Administration of LV (100 or 200 mg/kg; twice daily on days 4-6) reduced the RTX concentration in the liver 2-4-fold on days 7, 9, and 11 compared with controls. A model is proposed where LV and/or its anabolic products can compete with RTX uptake into tissues and interfere with the homeostatic regulation of RTX polyglutamates. These data support the use of LV rescue in the small minority of patients treated with RTX who present with a severe pattern of antiproliferative toxicities. The use of LV is not recommended routinely because the antitumor activity of RTX may similarly be reversed.

Comparison of thymidylate synthase (TS) protein up-regulation after exposure to TS inhibitors in normal and tumor cell lines and tissues

Thymidylate synthase (TS) is an important target for cancer chemotherapy. However, several mechanisms of resistance to TS inhibitors have been described. One mechanism that may be relevant to short-term exposure to TS inhibitors occurs as a result of disruption of the autoregulatory loop, which allows TS to control its own translation. This disruption leads to up-regulation of TS protein and is generally thought to decrease efficacy. This study has investigated TS protein up-regulation using a range of TS inhibitors in both tumor and nonmalignant cell lines in vitro and in vivo. Up-regulation of TS protein showed a time-, dose-, and cell-type-specific response to treatment with ZD9331. This response was observed in W1L2 cells treated for 24 h at equitoxic doses of raltitrexed (6-fold), ZD9331 (10-fold), fluorouracil (5-fold), LY231514 (7-fold), AG337 (7-fold), and BW1843U89 (3-fold). Up-regulation was observed over a range of doses. Elevation of TS protein only persisted up to 12 h after removal of drug. The extent of induction does not depend on basal TS levels. Nontransformed human fibroblasts showed significantly greater up-regulation of TS protein than tumor cells exposed to an equitoxic dose of ZD9331. In vivo experiments using the L5178Y thymidine kinase -/- mouse lymphoma implanted into DBA2 mice also showed greater up-regulation of TS protein in normal intestinal epithelial cells compared with tumor cells. These results confirm that TS up-regulation is a common feature of TS inhibition in tumor cells and that it may occur to a greater extent in normal tissues, although the clinical implications of these findings remain to be determined.

Cellular pharmacology and in vivo activity of a new anticancer agent, ZD9331: a water-soluble, nonpolyglutamatable, quinazoline-based inhibitor of thymidylate synthase

ZD9331 is a drug that was developed from a potent class of water-soluble, C7-methyl-substituted, quinazoline-based inhibitors of thymidylate synthase (TS) that are transported into cells via a saturable, carrier-mediated system (reduced folate carrier, or RFC) but are not substrates for folylpolyglutamate synthetase. ZD9331 is the gamma-tetrazole analogue of 2-desamino-2, 7-dimethyl-N10-propargyl-2'fluoro-5,8-dideaza folate (ZM214888), with a TS Ki of approximately 0.4 nM. ZD9331 exhibits potent growth inhibitory and cytotoxic activity; e.g., IC50 for the inhibition of human W1L2 lymphoblastoid cell line was 7 nM. The addition of thymidine to the culture medium increased the IC50 in W1L2 cells >10, 000-fold, demonstrating the high specificity of the drug for TS. ZD9331 is transported into cells predominantly via the RFC. Accordingly, it competes with methotrexate (MTX) and folinic acid for cellular uptake and has reduced activity against two cell lines with low expression of the RFC (L1210:1565 and CEM/MTX). In addition, a cell line with acquired resistance to ZD9331 displays reduced uptake of both ZD9331 and MTX. A mouse cell line (L1210:RD1694), with acquired resistance to ZD1694 due to reduced folylpolyglutamate synthetase activity, was not significantly cross-resistant to ZD9331. The flux through TS, as measured by 3H release from 5-[3H]deoxyuridine, was rapidly inhibited when cells were incubated with ZD9331. However, because ZD9331 cannot form polyglutamates, TS activity recovered rapidly once cells were placed in drug-free medium. The minimum curative dose of ZD9331 in the i.m. L5178Y TK-/- tumor model was approximately 3 mg/kg when given by 24-h continuous infusion, and it was 25-50 mg/kg when given by a single i.p. or i.v. injection. ZD9331 had antitumor activity against the L5178Y TK+/- tumor when administered by 7-day continuous infusion; growth delays of more than 5 days (and some cures) were seen at doses of 25-50 mg/kg/day. At higher doses, significant weight loss (gastrointestinal toxicity) and myelosuppression (neutropenia and thrombocytopenia) were observed, suggesting that these may be dose-limiting toxicities in the Phase I clinical studies.

Quinazoline thymidylate synthase inhibitors: methods for assessing the contribution of polyglutamation to their in vitro activity

Many quinazoline thymidylate synthase (TS) inhibitors undergo intracellular metabolism to polyglutamate forms which can significantly alter their activity and pharmacodynamics through improved TS inhibition and drug retention. When a series of quinazolines was tested for inhibitory activity towards TS (IC50 0.001-2 microM) and the growth of L1210 cells (IC50 0.005-10 microM), no direct correlation was observed. However, a very good correlation was apparent if a L1210 variant cell line (L1210: RD1694) was used. This line is deficient in its ability to form antifolate polyglutamates. A number of other intact cell methods have also been developed which estimate the contribution that intracellular polyglutamation makes to a compound's activity. These assays were validated using a series of quinazoline-based TS inhibitors with well-defined activity for TS, folypolyglutamate synthetase (FPGS) and the reduced-folate cell membrane carrier (RFC). Short-exposure growth-inhibition assays or the measurement of TS activity in situ after various incubation times, followed by different lengths of time in drug-free medium, can indicate both the speed and extent of appearance of retentive forms (usually polyglutamates). Continuous-exposure growth-inhibition assays, in the presence of leucovorin (LV), are also useful, since only the growth-inhibitory potency of polyglutamated analogues is significantly decreased by LV. Highly polyglutamated compounds, e.g. ZD1694, are virtually inactive in the presence of a high concentration of LV. It is proposed that these methods, when considered together, provide a greater degree of information concerning the rate and extent of polyglutamation of a particular compound than isolated FPGS assays alone.

Quinazoline-based thymidylate synthase inhibitors: relationship between structural modifications and polyglutamation

Quinazoline-based analogues of folic acid are a group of thymidylate synthase (TS) inhibitors that display a wide spectrum of activity for cultured tumour cells, partly due to their differential ability to form polyglutamate metabolites that are (i) more potent TS inhibitors and (ii) not readily effluxed from cells. The rate of cell membrane transport and folylpolyglutamate synthetase substrate activity influence compound polyglutamation. A series of intact-cell assays has been used to determine how specific modifications of 2-desamino-2-methyl-N10-propargyl-5,8-dideazafolate (ICI 198583) affect compound polyglutamation. Those containing the 'classical' glutamate structure were usually, but not always, well polyglutamated intracellularly. Replacement of N10 propargyl with smaller aliphatic substituents, particularly when combined with replacement of the benzene ring with thiophene or thiazole heterocycles, was beneficial for antitumour activity through polyglutamate formation. Fluorination of the benzene, particularly if a F was adjacent to the 'bridge region' (3'F or 2',5'diF), also gave compounds with a high dependence on polyglutamation for activity. Those analogues with 2-CH2OH or NH2 substituents were poor substrates for the reduced-folate cell membrane carrier which can account for their reduced polyglutamation rate and hence growth-inhibitory activity. A large decrease or prevention of polyglutamation was achieved by the introduction of CH3, CH2CH3, Br or C1 on C7. The concomitant enhancement in TS inhibition by these modifications gave compounds active under continuous-exposure cell culture conditions. Some ICI 198583 analogues had the glutamate moiety replaced with unnatural amino acids or dipeptides. Only the L-gamma-L-glu analogue (a polyglutamate metabolite of ICI 198583) gave activity entirely attributable to polyglutamate formation.

The incidence and prevention of folate deficiency in a pregnant clinic population

Non-anemic women attending a public antenatal clinic were given, daily, a multivitamin tablet containing 78 mg. of elemental iron. The follow-up studies included an analysis of their diets. A total of 311 patients were included, of which one group received a supplement of 0.5 mg. folic acid and 0.005 mg. vitamin B(12). The incidence of megaloblastic bone marrow change in the unsupplemented group was 26% and of low blood folates approximately 50%. The incidence of megaloblastic changes was sharply reduced in the supplemented group and the blood folates were elevated to supranormal levels, indicating that the dose of folic acid used may have been above the minimal requirement. Formiminoglutamic acid (FIGLU) excretion could not be correlated with other parameters of folate deficiency. Neutrophil lobe counts did not relate to megaloblastic changes or low folate levels unless there was more than 5% hypersegmentation. The dietary intake was suboptimal in total calories, iron and food folate.

Nutritional anemia and megaloblastosis in pregnancy

Macrogranulocytic and/or erythroid megaloblastic bone marrow changes which could not be accurately predicted from the hematologic findings in the blood were present in 25% of 305 mildly to moderately anemic pregnant women attending a public antepartum clinic in Montreal. Iron deficiency was the primary cause of anemia in most instances. Serum folate activity of less than 4.1 ng./ml. and/or serum vitamin B(12) levels of less than 100 pg./ml. were present in 90% of the 77 patients having these bone marrow changes, whereas approximately one-third of 228 patients with normoblastic marrow had these low values. Red cell folate did not correlate as well as serum folate activity with bone marrow changes. After treatment with oral folic acid in the range of 0.2 mg. to 0.8 mg., daily, for seven to 14 days, the megaloblastic and macrogranulocytic changes in patients with low serum folate activity and normal serum vitamin B(12) values disappeared in 15 of 21 patients. Of five women having both low folate and vitamin B(12) values, three failed to respond and two showed only partial improvement after 0.4 mg. of folic acid daily, per os, for 10 days. The average diet of these anemic women was suboptimal in folate and in iron.