Characteristics of GPs and scientific publications
Interviews with 20 GPs and the data from three publications [21,22,23] were analysed.
Three GPs were contacted, but refused to be involved in the study because they lacked time. The 20 GPs interviewed had a mean age of 47 years (range: 27 to 70 years). They had been practicing in the primary care setting for a mean of 18 years (range: 2 months to 37 years). Thirteen were salaried (public sector), and seven worked in private practice. Twelve were women. All but one of the GPs were interviewed with the same seven clinical cases (see Additional file). The remaining GP was interviewed with only five of the seven clinical cases because of a lack of time. Interviews lasted between 15 and 35 min.
One of the publications studied [21] investigated the reasons underlying antibiotic choice by GPs, but focused on broad-spectrum and fluoroquinolone antibiotics. The other two publications [22, 23] did not address the problem of antibiotic choice as a primary objective, but they reported findings regarding the factors involved in antibiotic choice.
Antibiotic choice is guided by four main factors
Our analysis of GP interviews and scientific publications (steps 1 and 2) revealed that antibiotic choice was guided by four main factors: the probable causal bacteria, the patient’s condition, antibiotic properties and general practitioner-related factors.
Antibiotic choice is guided by the probable causal bacteria
Almost all the GPs reported that they chose the antibiotic to prescribe according to the bacterium causing the infection (Ex1). Identification of the causal bacterium is not easy in primary care, because GPs cannot necessarily perform bacterial tests during consultations. They therefore have to use the patient’s symptoms and epidemiological data (e.g. the prevalence of causal agents) to formulate hypotheses concerning the most likely causal bacterium (Ex2). The GPs then choose an antibiotic to which they presume the bacterium is susceptible.
Ex1 (from publication [21]): “The likely infecting organism was also reported as a major influence on which antibiotic to prescribe”.
Ex2: “For otitis… if there is also conjunctivitis, then I prescribe amoxicillin clavulanic-acid, because I suspect the pathogen to be Haemophilus influenzae”.
In some cases, GPs may decide to confirm their hypotheses, by prescribing bacteriological tests (e.g. urine culture). However, as the results of these tests may take some time to obtain, GPs are nevertheless obliged to prescribe antibiotics in accordance with their hypothesis, before subsequent readjustment, if necessary, on the basis of bacteriological tests (Ex3).
Ex3: “For uncomplicated pyelonephritis… I think I would prescribe a urine culture test, and then adjust the prescription according to the result of the test (…). I first prescribe ofloxacin, because of its broad-spectrum and then readjust after 48 hours, according to the results of the bacterial test. For example, if the bacterium is susceptible to amoxicillin, I would readjust and prescribe amoxicillin. But, without the result of the bacterial test, I would never prescribe amoxicillin because of the risk of resistance, unlike fluoroquinolones for which susceptibility is higher.”
A few GPs also reported a preference for prescribing antibiotics likely to do little collateral damage (i.e. those not known to generate bacterial resistance) (Ex4).
Ex4: “I now prescribe fluoroquinolones as a first-line treatment, to avoid the emergence of extended-spectrum beta-lactamases”.
Antibiotic choice is guided by the patient’s condition
All GPs reported taking patient profile (age, allergy, pregnancy), medical history and comorbid conditions (e.g. renal failure) into account. For example, for frail elderly patients or patients with comorbid conditions likely to worsen the infection (e.g. diabetes), the GPs preferred to prescribe antibiotics that were “powerful” or taken in long courses (Ex5, Ex6).
Ex5: “For pneumonia in young people I give amoxicillin (...). For elderly people, I prefer to give amoxicillin/clavulanic acid, which is more efficient, especially after flu-like conditions, which often leave patients frailer”.
Ex6: “For acute cystitis, I usually give Monuril® (…). But today, I saw a patient who had an history of pyelonephritis. Because of this antecedent, I was worried about prescribing Monuril® as a single-dose… So, I decided to prescribe lomefloxacin for three days. So yes, because of her medical history, I wanted to be more effective than the usual treatment”.
All GPs also said that they took the patient’s symptoms and the course of the infection into account when prescribing antibiotics. For example, they reported a preference for broad-spectrum antibiotics (e.g. fluoroquinolones) for serious, intense, risky, persistent, repeated or complicated infections (Ex7, Ex8).
Ex7: “For otitis… if symptoms are severe I prescribe Oflocet®, otherwise I give Augmentin®”.
Ex8: “For childhood pharyngitis… Amoxicillin as the first-line treatment (…). But if the patient’s condition deteriorates, then I add clavulanic acid, because I want to be more effective and to cover more of the pathogens likely to cause upper respiratory tract infections”.
Some GPs also said that they took the patient’s history of antibiotic treatment into account. They avoid prescribing antibiotics that had not proved effective in the patient in the past, and antibiotics already prescribed to the patients in the last few months, so as to prevent the occurrence of bacterial resistance (Ex9).
Ex9: “For prostatitis … I avoid fluoroquinolones (…) if the patient has taken fluoroquinolones in the last three months”.
Patient preferences were also taken into account. GPs said that they sometimes adjusted their prescriptions according to the patient’s preference in terms of the type of molecule, galenic formulation or mode of administration (Ex10, Ex11).
Ex10: (from publication [21]): “Many GPs explained how fluoroquinolones were popular with a range of patients due to the low incidence of side-effects and the twice daily dose”.
Ex11: “I listen a little to what the patient says… if the patient repeatedly had sinusitis and tells me that one particular antibiotic is efficient, then I prescribe this antibiotic if it is appropriate. So, yes, sometimes, the patient’s wishes may play a role in antibiotic choice”.
Antibiotic choice is guided by antibiotic properties
Most GPs reported that they considered the efficacy of the antibiotic when making their choice. They reported a preference for antibiotics with marketing authorisation for the infection, good pharmacokinetic parameters (e.g. rapid action), and antibiotics known to treat the type of infection concerned effectively (Ex12, Ex13).
Ex12: “For sinusitis… I prescribe Orelox®, because it has always been effective”.
Ex13: “For prostatitis …. I give ofloxacin… This antibiotic reaches high concentrations in the urinary tract, and this is important because prostatitis is a deep infection”.
Many GPs also said that they took the adverse effects of antibiotics into account (Ex14). They avoided prescribing antibiotics known to have adverse effects (e.g. fluoroquinolone-induced Achilles tendinitis, the adverse gastrointestinal effects of amoxicillin clavulanic-acid).
Ex14: “For pharyngitis… I prescribe amoxicillin (...). It is very effective, and it has the least side effects”.
The administration protocol was often taken into account. Antibiotics with a convenient administration protocol (i.e. low daily dose, short-course treatment) were preferred, to maximise patient observance (Ex15). Administration route, galenic formulation and the flavour of the preparation may also be adjusted to patient profile, to encourage patients to take their treatment (Ex16). For example, if the patient has trouble swallowing tablets, antibiotics may be prescribed as syrups or suspensions, or for intramuscular injection.
Ex15: “For cystitis… I prescribe Monuril® as a single dose (…). It is very convenient for patients”.
Ex16: “Josacin® is highly suitable for use in children because of its strawberry taste”.
Some GPs also explained that they avoided prescribing antibiotics from classes considered to be precious, such as fluoroquinolones, and third-generation cephalosporins. They reserved these antibiotics for very serious cases and for cases of infection with highly resistant bacteria (Ex17, Ex18).
Ex17 (from publication [21]) “They needed to keep broad-spectrum antibiotics in reserve for severely ill patients”.
Ex18: “For pharyngitis, I avoid third-generation cephalosporins. We have to preserve them.”
Very few GPs reported taking cost into account in their choice of antibiotic. Those that did considered the cost of the drug itself (Ex19), but also the costs relating to hospital admission that antibiotic administration might prevent.
Ex19: “I won’t prescribe pristinamycin as a first-line treatment because it is expensive for our national health insurance”.
Antibiotic choice is guided by general practitioner-related factors
Antibiotic choice is also guided by the GPs’ antibiotic knowledge (Ex20), habits, experience (Ex21), and preferences (Ex22). These preferences seem to differ between GPs.
Ex20: “For pyelonephritis… I used to prescribe quinolones because that was what we prescribed during my medical training, but I think things are changing…”.
Ex21: “For cystitis… Monuril® (…). This is the antibiotic recommended for first-line treatment, and I have also had good experiences with this drug in terms of side effects and efficacy.”
Ex22: “I know we can prescribe other antibiotics in this situation, but I prefer Orelox®.”
All GPs said that they used external resources to guide their choice of antibiotic. Clinical practice guidelines were the most frequently mentioned resource, followed by antibiotic websites, personal memos, and scientific publications (Ex23). GPs were also found to be influenced by the practices of colleagues, and of specialists in hospitals (Ex24). One GP reported being influenced by sales representatives from the pharmaceutical industry.
Ex23: “I follow the recommendations in clinical practice guidelines (...) I also update my knowledge with the antibiotic website”.
Ex24 (from publication [21]): “GPs’ prescribing choices were also influenced by discussions with other GPs at practice meetings”.
Half the GPs also reported that they followed their own instincts when choosing antibiotics (Ex25), and one even admitted that antibiotic choice was influenced by his/her mood at the time of prescription (Ex26).
Ex25: “For cystitis… instinctively, I prescribe Monuril®”.
Ex26: “For sinusitis… I give Augmentin® or Zinnat®, depending on my mood”.
Some GPs also said that they were guided by their fears (Ex27) and by feelings of responsibility for their patients (Ex28). They explained that they sometimes prescribed very powerful antibiotics not recommended in guidelines because they were concerned about the possibility of complications occurring in the patient and because they wanted to do their best for their patients.
Ex27: “For pneumonia… I should give amoxicillin, but this is the only situation in which I prescribe amoxicillin-clavulanic acid. I prefer to be more effective. Pneumonia is a source of anxiety for doctors, and for this reason, doctors may deliberately decide to prescribe outside of the guidelines”.
Ex28 (from publication [21]): “Most of them justified their current liberal prescribing of fluoroquinolones on the basis of their duty to do the best for “the patient in front of them””.
Model of the rationale used by general practitioners in their choice of antibiotic
The model resulting from our analysis, including all the factors involved in antibiotic choice, is presented in Fig. 1.