Association between antibiotic resistance and community prescribing: a critical review of bias and confounding in published studies

Educational interventions to improve antibiotic use in the community: report from the International Forum on Antibiotic Resistance (IFAR) colloquium, 2002

National and international strategies for the control of antibiotic resistance recommend education for health-care professionals and the public to promote prudent antibiotic use. This paper, based on discussions at the 2002 colloquium of the International Forum on Antibiotic Resistance (IFAR), provides an international discourse between theoretical approaches to behaviour change and practical experience gained in large-scale antibiotic use educational campaigns. Interventions are more likely to be effective if their aim is to change behaviour, rather than provide information. They should target all relevant groups, especially parents, children, day-care staff, and health-care professionals. They should use clear and consistent messages concerning bacterial versus viral infection, prudent antibiotic use, symptomatic treatment, and infection-control measures (eg, handwashing). Campaigns should use a range of communications using pilot-testing, strong branding, and sociocultural adaptation. Prime-time television is likely to be the most effective public medium, while academic detailing is especially useful for health-care professionals. Multifaceted interventions can improve antibiotic prescribing to some degree. However, there are few data on their effects on resistance patterns and patient outcomes, and on their cost-effectiveness. Current research aims include the application of behaviour-change models, the development and validation of prudent antibiotic prescribing standards, and the refinement of tools to assess educational interventions.

Antibiotic use in Hispanic households, New York city

Trained interviewers visited 631 inner city households to determine community prevalence and predictors of antibiotic use. Infectious disease symptoms were reported in 911 (33.2%) of 2,743 household members in the previous 30 days: medical attention was sought by 441 (48.4%) of 911 persons, and 354 (38.9%) of 911 took antibiotics for symptoms. Reported symptoms were respiratory (68.9%), gastrointestinal (15.3%), fever (12.8%), and skin infection (2.8%). Medical attention was sought significantly more often among those with chronic illness, those born in the United States, and those with fever, runny nose, or skin infections (all p<0.05). Antibiotics were taken significantly more often among those with poor health, those who spent more time at home, and those with fever and respiratory symptoms. Interventions to promote judicious use of antibiotics must include clinicians and the public, and for the Hispanic population such interventions must also be culturally relevant and provided in Spanish.

Clinical role of beta-lactam/beta-lactamase inhibitor combinations

The use of beta-lactamase inhibitors in combination with beta-lactam antibiotics is currently the most successful strategy to combat a specific resistance mechanism. Their broad spectrum of activity originates from the ability of respective inhibitors to inactivate a wide range of beta-lactamases produced by Gram-positive, Gram-negative, anaerobic and even acid-fast pathogens. Clinical experience confirms their effectiveness in the empirical treatment of respiratory, intra-abdominal, and skin and soft tissue infections. There is evidence to suggest that they are efficacious in treating patients with neutropenic fever and nosocomial infections, especially in combination with other agents. beta-Lactam/beta-lactamase inhibitor combinations are particularly useful against mixed infections. Their role in treating various multi-resistant pathogens such as Acinetobacter species and Stenotrophomonas maltophilia are gaining importance. Although, generally, they do not constitute reliable therapy against extended-spectrum beta-lactamase producers, their substitution in place of cephalosporins appears to reduce emergence of the latter pathogens. Similarly, their use may also curtail the emergence of other resistant pathogens such as Clostridium difficile and vancomycin-resistant enterococci. beta-Lactam/beta-lactamase inhibitor combinations are generally well tolerated and their oral forms provide effective outpatient therapy against many commonly encountered infections. In certain scenarios, they could even be more cost-effective than conventional combination therapies. With the accumulation of so much clinical experience, their role in the management of infections is now becoming more clearly defined.

Decreasing beta-lactam resistance in Pneumococci from the Memphis region: analysis of 2,152 isolates From 1996 to 2001

STUDY OBJECTIVES

The Memphis region historically has had high pneumococcal antibiotic resistance rates. In recent years, we have seen a significant shift in antibiotic use away from beta-lactams toward the newer quinolones and macrolides. We hypothesized that these changes would cause a shift in pneumococcal antibiotic resistance patterns.

DESIGN

Retrospective cohort study.

SETTING

A large private hospital system.

PATIENTS AND METHODS

We analyzed the antibiotic susceptibility patterns of 2,152 pneumococcal isolates obtained in the Memphis area from 1996 to 2001. Isolates were categorized as invasive or noninvasive and antibiotic resistance was classified according to the 2000 guidelines of the National Committee for Clinical Laboratory Standards.

RESULTS

Over the study period, the proportion of penicillin-susceptible noninvasive pneumococcal isolates taken from children increased from 22 to 44% (p = 0.0004 [for trend across the 6-year period]). In noninvasive isolates taken from adults, penicillin susceptibility increased from 22 to 55% (p = 0.002), with a trend toward increasing sensitivity to cefotaxime (p = 0.02) in noninvasive isolates over the same period. The proportion of isolates with high-level penicillin resistance (ie, minimum inhibitory concentration, > or = 4 microg/mL) also decreased between 1996 and 2001 (p = 0.003). Clindamycin resistance in adult noninvasive isolates also declined (p = 0.002). The only adverse trend observed over this period was an increase in erythromycin resistance in noninvasive isolates from adults (p = 0.01). Resistance rates were significantly higher in children than in adults and were higher in noninvasive isolates than in invasive isolates.

CONCLUSIONS

The stabilization of beta-lactam resistance rates in our region suggests that a continuous increase in pneumococcal resistance to antibiotics is not inevitable and may be avoidable.

Upper respiratory tract infections in general practice: diagnosis, antibiotic prescribing, duration of symptoms and use of diagnostic tests

A diagnosis/antibiotic prescribing study was performed in 5 counties in Sweden for 1 week in November 2000. As part of this study, the characteristics and clinical management of patients with upper respiratory tract infections (n = 2899) in primary care were analyzed. Almost half of the patients were aged < 15 y and one-fifth of the patients consulted out of hours. Of all patients seeking primary care for upper respiratory tract infections, 56.0% were prescribed an antibiotic. Almost all patients who were given the diagnoses streptococcal tonsillitis, acute otitis media or acute sinusitis were prescribed antibiotics, compared to 10% of patients with common cold or acute pharyngitis. The most frequently prescribed antibiotic was penicillin V (79.2%) and this was even more pronounced out of hours, when the diagnoses otitis media and streptococcal tonsillitis were more frequently used. In patients with common cold and acute pharyngitis, the percentage who received antibiotics increased with increasing length of symptoms and increasing CRP levels. In patients with acute pharyngitis or streptococcal tonsillitis, antibiotics were prescribed less frequently provided streptococcal tests were performed. The management of patients with upper respiratory tract infections in general practice seems to be in good agreement with current Swedish guidelines. However, the study indicates some areas for improvement. The diagnosis of acute sinusitis seems to have been overestimated and used only to justify antibiotic treatment.

Differences in antibiotic prescribing patterns between general practitioners in Scandinavia: a questionnaire study

There has been a dramatic increase in the prevalence of antibiotic-resistant bacteria worldwide. In the Scandinavian countries at least 90% of total antibiotic use relates to outpatients and therefore it has become increasingly important to know the antibiotic prescription pattern of general practitioners (GPs) in order to implement and monitor changes in antibiotic prescribing. The aim of the present study was to evaluate the prescription patterns of GPs in Denmark, Norway and Sweden. In order to achieve a reasonable comparison, a questionnaire consisting of 7 case reports concerning upper and lower respiratory tract infections, urinary tract infections and skin and soft tissue infections was sent to 1,000 GPs in the 3 countries. In general, the guidelines for the treatment of bacterial infections in the individual countries were followed by the responders. In all 3 countries, penicillin V was still the drug most frequently used in upper and lower respiratory tract infections. The greatest difference in prescribing patterns among the countries was seen in the treatment of urinary tract infections, recurrent pharyngeal tonsillitis, acute otitis media and acute exacerbation of chronic bronchitis. There were also differences in the dosing regimens, length of treatment and use of diagnostic techniques.

Suboptimal antibiotic dosage as a risk factor for selection of penicillin-resistant Streptococcus pneumoniae: in vitro kinetic model

Optimizing pharmacokinetic/pharmacodynamic indices of antibiotics to obtain clinical and microbiological efficacy is essential, but dosing regimens must also be tailored to minimize the risk for emergence of resistance. The aim of the present study was to investigate whether certain concentrations of benzylpenicillin are critical for the selection of resistant subpopulations. A mixed culture of Streptococcus pneumoniae containing ca. 90% susceptible (MIC = 0.031 mg/liter), 9% intermediate (MIC = 0.25 mg/liter), and 1% resistant (MIC = 8 mg/liter) was studied in an in vitro kinetic model. The time that concentrations exceeded the MIC (T>MIC) for the three strains in the culture was varied by different initial concentrations of benzylpenicillin. Samples for viable counts were withdrawn at different times during 24 h and seeded on blood agar plates and on selective antibiotic-containing plates. The T>MIC varied from 46 to 100% for the susceptible strain, from 6 to 100% for the intermediate strain, and from 0 to 48% for the resistant strain. Our study, which may mimic the clinical situation with carriage of a mixed population of S. pneumoniae with different antibiotic susceptibilities, has shown that selection of resistant bacteria may easily occur if dosing regimens are only targeted toward fully susceptible strains.

The patient's role in the spread and control of bacterial resistance to antibiotics

As the ultimate consumers, patients play an important role in the emergence, spread and control of bacterial resistance to antibiotics. Improved knowledge of antibiotics and the problem of resistance, as well as a better understanding of beliefs, pressures/concerns, and expectations, from both the patient's and physician's perspectives, are fundamental for controlling antibiotic use. There is growing evidence to suggest that empowering patients through implementation of patient-centered health-care strategies, such as shared decision-making, in conjunction with educational initiatives help to change attitudes and behavior, and improve access to and completion of appropriate antimicrobial therapy. This, in turn, may help to control the development and spread of resistance to antibiotics.

Pharmaco-epidemiology and -economics should be developed more extensively in veterinary medicine

Pharmaco-epidemiology, which has emerged within the last 20 years as a new discipline in human medicine, deals with the quantities of drugs consumed and their effects on populations in terms of epidemiological concepts and tools. To a lesser extent, it is also practised in veterinary medicine. The applications presented in this review are illustrative of pharmaco-epidemiological and -economical concepts. Assessment of drug consumption, the study of adverse drug effects, and the economic implications of drug use are the three main fields considered. Developments can be expected in veterinary medicine within the next few years relative to novel areas of interest such as antimicrobial resistance and new therapeutic class uses. These applications will require methodological progress and the elimination of current gaps. Pharmaco-epidemiological methods need to be developed, which implies close co-operation between statisticians, pharmacologists, veterinary practitioners and epidemiologists. A greater use of the term 'pharmaco-epidemiology' as a keyword in literature would facilitate recognition of this domain which associates closely epidemiology and pharmacology.

A survey of antimicrobial drug resistance in respiratory tract pathogens, isolated in a northern Italian teaching hospital between 1990 and 1999

Drug susceptibility test results of respiratory tract pathogens, isolated from patients admitted to the Clinic of Respiratory Diseases of the IRCCS San Matteo Hospital, University of Pavia (Italy) between 1990 and 1999, were retrospectively evaluated. A total of 1366 bacterial isolates were collected, including 499 gram-positive and 867 gram-negative strains. In comparison to methicillin-susceptible Staphylococcus aureus, the methicillin-resistant strains (MRSA) showed high levels of resistance to many selected antibiotics, except for glycopeptides. Resistance rates to beta-lactams were high in both Pseudomonas aeruginosa and in the other gram-negative isolates, while aminoglycoside and ciprofloxacin resistance was less than 20%. Some pathogens became more resistant to selected antimicrobials during the observation period, including staphylococci to methicillin, MRSA to ciprofloxacin, P. aeruginosa isolates to imipenem and ciprofloxacin, and the other gram-negative strains to almost all drugs considered, with the exception of cefotaxime and cotrimoxazole.

Over-the-counter acquisition of antibiotics in the Maltese general population

Few studies have studied the frequency of over-the-counter acquisition of antibiotics in western countries. In order to provide an insight into these practices in Malta, attitudes towards antibiotic use in the general public were researched through a structured interview. Nineteen percent admitted that they took antibiotics without prescription and 11% of parents replied that they had given antibiotics to their children without prescription. These antibiotics were mainly self-administered for upper respiratory tract symptoms, particularly sore throat, with community pharmacies being the major source in more than 85% of cases. The study indicates the need for an educational campaign on proper antibiotic use amongst the Maltese general public.