European Surveillance of Antimicrobial Consumption (ESAC): outpatient macrolide, lincosamide and streptogramin (MLS) use in Europe

Consumption of macrolides, lincosamides and streptogramins in the community, European Union/European Economic Area, 1997-2017

OBJECTIVES

Data on the consumption of macrolides, lincosamides and streptogramins (MLS) in the community were collected from 30 EU/European Economic Area (EEA) countries over two decades. This article reviews temporal trends, seasonal variation, presence of change-points and changes in composition of the main subgroups of MLS.

METHODS

For the period 1997-2017, data on consumption of MLS, i.e. ATC group J01F, in the community and aggregated at the level of the active substance, were collected using the WHO ATC/DDD methodology (ATC/DDD index 2019). Consumption was expressed in DDD per 1000 inhabitants per day and in packages per 1000 inhabitants per day. Consumption of MLS was analysed and presented as trends, seasonal variation, presence of change-points and compositional changes, using a classification based on mean plasma elimination half-life for macrolides.

RESULTS

In 2017, consumption of MLS in the community expressed in DDD per 1000 inhabitants per day varied by a factor of 13 between countries with the highest (Greece) and the lowest (Sweden) consumption. Consumption of MLS did not change significantly up to 2003, after which it significantly increased up to 2007. No significant change was observed after 2007. Consumption of MLS showed high seasonal variation. The proportional consumption of long-acting macrolides significantly increased over time compared with that of intermediate-acting macrolides, and proportional consumption of the latter increased compared with that of short-acting macrolides.

CONCLUSIONS

Consumption of MLS did not change significantly over time during 2007-2017, while the proportional consumption of long-acting macrolides increased. Seasonal variation remained high, which suggests that MLS are still prescribed inappropriately in many countries.

Change-points in antibiotic consumption in the community, European Union/European Economic Area, 1997-2017

OBJECTIVES

Surveillance of antibiotic consumption in the community is of utmost importance to inform and evaluate control strategies. Data on two decades of antibiotic consumption in the community were collected from 30 EU/European Economic Area (EEA) countries. This article reviews temporal trends and the presence of abrupt changes in subgroups of relevance in antimicrobial stewardship.

METHODS

For the period 1997-2017, data on yearly antibiotic consumption in the community, aggregated at the level of the active substance, were collected using the WHO ATC classification and expressed in DDD (ATC/DDD index 2019) per 1000 inhabitants per day. We applied a range of non-linear mixed models to assess the presence of changes in the consumption of antibacterials for systemic use (ATC group J01) and eight antibiotic subgroups.

RESULTS

For the majority of the studied groups, a country-specific change-point model provided the best fit. Depending on the antibiotic group/subgroup and on the country, change-points were spread out between 2000 and 2013.

CONCLUSIONS

Due to the heterogeneity in antibiotic consumption in the community across EU/EEA countries, a country-specific change-point model provided the better fit. Given the limitations of this model, our recommendation for the included countries is to carefully interpret the country-specific results presented in this article and to use the tutorial included in this series to conduct their own change-point analysis when evaluating the impact of changes in regulations, public awareness campaigns, and other national interventions to improve antibiotic consumption in the community.

Consumption of antibiotics in the community, European Union/European Economic Area, 1997-2017: data collection, management and analysis

OBJECTIVES

This article introduces a series of articles on antibiotic consumption in the community between 1997 and 2017, which provide an update of previous articles covering the periods 1997-2003 and 1997-2009.

METHODS

In this article, differences in participating countries, the ATC/DDD classification system, and data collection, validation and analysis between the current and previous series are described.

RESULTS

In the previous series, 33 European countries provided valid data for further analysis, while the current series focused on 30 countries belonging to the EU or the European Economic Area (EEA). For both series, data were collected in accordance with the WHO ATC classification system. While the previous series reported data in accordance with the ATC/DDD index 2011, the current series employed the ATC/DDD index 2019. Both series focused on consumption of antibacterials for systemic use (ATC J01) and collected data expressed in DDD per 1000 inhabitants per day and packages per 1000 inhabitants per day. When studying consumption expressed in packages per 1000 inhabitants per day, countries reporting total care data, i.e. community and hospital sector combined, were included in the previous series but excluded in the current series. While the previous series used non-linear mixed models to evaluate time trends in antibiotic consumption, the current series allowed for inclusion of change-points with a data-driven location. In addition, both series assessed the composition and quality of antibiotic consumption in the EU/EEA.

CONCLUSIONS

The updated analyses of two decades of ESAC-Net data provide the most comprehensive and detailed description of antibiotic consumption in the community in Europe.

Evidence of mutations conferring resistance to clarithromycin in wastewater and activated sludge

The occurrence of clarithromycin in wastewater samples and of the activated sludge bacteria possibly resistant to this pharmaceutical was the object of the study. Samples of wastewater or activated sludge were taken from a municipal wastewater treatment plant in summer and winter and characterised regarding their clarithromycin concentrations and the presence of nucleic acid fragments (Cla-sequences) known to be responsible for clarithromycin resistance in Helicobacter pylori. The concentrations of clarithromycin in raw wastewater were about 1086-2271 ng/L. Around 50-60% less of the pharmaceutical was found in treated wastewater. The concentrations were much higher in winter samples, as compared to summer samples. The clarithromycin resistance markers in H. pylori were detected by fluorescence in situ hybridisation in activated sludge bacterial cells. Cla-sequences were found in all the detected Proteobacteria, independently of the sampling season. Among nitrifying or phosphate or glycogen accumulating bacteria only Nitrosomonas spp. revealed presence of the clarithromycin sequences.

Trends in macrolide resistance of respiratory tract pathogens in the paediatric population in Serbia from 2004 to 2009

We report the first study of macrolide resistance in respiratory tract pathogens in a Serbian paediatric population. It included 5293 Streptococcus pneumoniae, 4297 Streptococcus pyogenes, 2568 Moraxella catarrhalis and 1998 Haemophilus influenzae isolates derived from the respiratory tract and 110 invasive isolates from children aged up to 18 years during 2004-2009. Over the 6-year period, a significant increase (P < 0·01) in macrolide resistance was found in both S. pneumoniae and S. pyogenes that reached 45% and 19%, respectively, in 2009. In the same period, consumption of macrolides increased continually from 2·46 to 5·8 defined daily dose/1000 inhabitants per day. The increase in macrolide resistance in S. pyogenes correlated with consumption of total macrolide and long-acting macrolides (r = 0·879, P = 0·05 and r = 0·922, P = 0·026, respectively). A similar trend was observed in pneumoccoci, although it did not reach statistical significance. The growing problem of macrolide resistance in pneumococci and S. pyogenes in Serbia requires further vigilant surveillance.

Blood, tissue, and intracellular concentrations of azithromycin during and after end of therapy

Although azithromycin is extensively used in the treatment of respiratory tract infections as well as skin and skin-related infections, pharmacokinetics of azithromycin in extracellular space fluid of soft tissues, i.e., one of its therapeutic target sites, are not yet fully elucidated. In this study, azithromycin concentration-time profiles in extracellular space of muscle and subcutaneous adipose tissue, but also in plasma and white blood cells, were determined at days 1 and 3 of treatment as well as 2 and 7 days after the end of treatment. Of all compartments, azithromycin concentrations were highest in white blood cells, attesting for intracellular accumulation. However, azithromycin concentrations in both soft tissues were markedly lower than in plasma both during and after treatment. Calculation of the area under the concentration-time curve from 0 to 24 h (AUC(0-24))/MIC(90) ratios for selected pathogens suggests that azithromycin concentrations measured in the present study are subinhibitory at all time points in both soft tissues and at the large majority of observed time points in plasma. Hence, it might be speculated that azithromycin's clinical efficacy relies not only on elevated intracellular concentrations but possibly also on its known pleotropic effects, including immunomodulation and influence on bacterial virulence factors. However, prolonged subinhibitory azithromycin concentrations at the target site, as observed in the present study, might favor the emergence of bacterial resistance and should therefore be considered with concern. In conclusion, this study has added important information to the pharmacokinetic profile of the widely used antibiotic drug azithromycin and evidentiates the need for further research on its potential for induction of bacterial resistance.

A genomic portrait of the emergence, evolution, and global spread of a methicillin-resistant Staphylococcus aureus pandemic

The widespread use of antibiotics in association with high-density clinical care has driven the emergence of drug-resistant bacteria that are adapted to thrive in hospitalized patients. Of particular concern are globally disseminated methicillin-resistant Staphylococcus aureus (MRSA) clones that cause outbreaks and epidemics associated with health care. The most rapidly spreading and tenacious health-care-associated clone in Europe currently is EMRSA-15, which was first detected in the UK in the early 1990s and subsequently spread throughout Europe and beyond. Using phylogenomic methods to analyze the genome sequences for 193 S. aureus isolates, we were able to show that the current pandemic population of EMRSA-15 descends from a health-care-associated MRSA epidemic that spread throughout England in the 1980s, which had itself previously emerged from a primarily community-associated methicillin-sensitive population. The emergence of fluoroquinolone resistance in this EMRSA-15 subclone in the English Midlands during the mid-1980s appears to have played a key role in triggering pandemic spread, and occurred shortly after the first clinical trials of this drug. Genome-based coalescence analysis estimated that the population of this subclone over the last 20 yr has grown four times faster than its progenitor. Using comparative genomic analysis we identified the molecular genetic basis of 99.8% of the antimicrobial resistance phenotypes of the isolates, highlighting the potential of pathogen genome sequencing as a diagnostic tool. We document the genetic changes associated with adaptation to the hospital environment and with increasing drug resistance over time, and how MRSA evolution likely has been influenced by country-specific drug use regimens.

Are children carrying the burden of broad-spectrum antibiotics in general practice? Prescription pattern for paediatric outpatients with respiratory tract infections in Norway

OBJECTIVES

To investigate the antibiotic prescription pattern and factors that influence the physicians' choice of antibiotic.

DESIGN

Observational study.

SETTING

Primary healthcare in Norway, December 2004 through November 2005.

PARTICIPANTS

426 general practitioners, GPs, in Norway, giving 24 888 respiratory tract infection episodes with 19 938 children aged 0-6 years.

OUTCOME MEASURES

Assess antibiotic prescription details and patient and GP characteristics associated with broad-spectrum and narrow-spectrum antibiotic use.

RESULTS

Of the 24 888 episodes in the study, 26.2% (95% CI 25.7% to 26.8%) included an antibiotic prescription. Penicillin V accounted for 42% and macrolide antibiotics for 30%. The prescription rate varied among the physicians, with a mean of 25.5% (95% CI 24.2% to 26.7%). Acute tonsillitis gave the highest odds for a prescription, OR 33.6 (95% CI 25.7% to 43.9%), compared to 'acute respiratory tract infections and symptoms' as a reference group. GPs with a prescription rate of 33.3% or higher had the larger probability for broad-spectrum antibiotic prescriptions, OR 3.33 (95% CI 2.01% to 5.54%). Antibiotic prescriptions increased with increasing patient age.

CONCLUSIONS

We found a low antibiotic prescription rate for childhood respiratory tract infections. However, our figures indicate an overuse of macrolide antibiotics and penicillins with extended spectrum, more so than in the corresponding study including the adult population. Palatability of antibiotic suspensions and other administrative challenges affect medication compliance in children. To help combat antibiotic resistance, guidelines need to be followed, in particular for our youngest patients. TRIAL REGISTRATION NUMBER (CLINICALTRIALS.ORG): NCT00272155.

European Surveillance of Antimicrobial Consumption (ESAC): outpatient antibiotic use in Europe (1997-2009)

OBJECTIVES

To describe total outpatient systemic antibiotic use in Europe from 1997 to 2009 and to analyse statistically trends of total use and composition of use over time.

METHODS

For the period 1997-2009, data on outpatient use of systemic antibiotics aggregated at the level of the active substance were collected and expressed in defined daily doses (WHO, version 2011) and packages per 1000 inhabitants per day (DID and PID, respectively). Outpatient antibiotic (ATC J01) use in DID in the 33 European countries able to deliver valid data was analysed using longitudinal and compositional data analyses.

RESULTS

Total outpatient antibiotic use in 2009 varied by a factor of 3.8 between the countries with the highest (38.6 DID in Greece) and lowest (10.2 DID in Romania) use. For Europe, a significant increase was found in total outpatient antibiotic use, as well as a significant seasonal variation, which decreased over time from 1997 to 2009. Relative use of penicillins and quinolones significantly increased over time with respect to sulphonamides and trimethoprim, and relative use of quinolones increased with respect to macrolide/lincosamide/streptogramin as well. More detailed analyses of these major antibiotic subgroups will be described in separate papers.

CONCLUSIONS

Outpatient antibiotic use in Europe measured as DID has increased since 1997, whereas seasonal variation has decreased over time. European Surveillance of Antimicrobial Consumption (ESAC) data on outpatient antibiotic use in Europe enable countries to audit their antibiotic use. Complemented by longitudinal and compositional data analyses, these data provide a tool for assessing public health strategies aimed at reducing antibiotic resistance and optimizing antibiotic prescribing.

Description of macrolide-resistant and potential virulent clones of Streptococcus pyogenes causing asymptomatic colonization during 2000-2006 in the Lisbon area

The asymptomatic oropharyngeal colonization rate by Streptococcus pyogenes was 10.7% in children (901 among 8,405 children 0-16 years old) and 3.3% in adults (37 among 1,126 households of children) in the Lisbon area during 2000-2006. Macrolide-resistant S. pyogenes from children (n = 149) was variable with time: 9.8-10.7% in 2000-2002, 28.1% in 2003, 19.6-2.7% in 2004-2005 and 14.6% in 2006. Eight lineages (97.3% of isolates) were identified based on at least 80% similarity of PFGE patterns, T types, emm types and multilocus sequence types (ST). The elevated frequency of macrolide resistance was associated with M phenotype lineages I (emm12/ST36) and V (emm4, emm75/ST39 and a novel emmstMrp6 type) and with one cMLS(B) lineage IV (emm28/ST52) known to be associated with upper respiratory tract and invasive infections. Significant associations (p < 0.05) between emm type/virulence genotype were found, such as emm1/speA (+) ssa (-), emm4/ssa (+) prtF1 (+), emm12/speA (-) ssa (-). The high prevalence (>20%) of speC, prtF1 or ssa was probably caused either by clonal dissemination (speC), or to horizontal gene transfer events (prtF1 and ssa). This report contributes to a better understanding of the molecular epidemiology and evolution of macrolide-resistant S. pyogenes causing symptom-free oropharyngeal colonization. These colonizing strains carry macrolide resistance and virulence genes capable of being transferred to other bacterial species sharing the same niche.

European Surveillance of Antimicrobial Consumption (ESAC): outpatient systemic antimycotic and antifungal use in Europe

OBJECTIVES

To assess the total outpatient systemic antimycotic and antifungal use in Europe, and to identify the antimycotic and antifungal substances most commonly used.

METHODS

Within ESAC (www.esac.ua.ac.be), using the anatomical therapeutic chemical (ATC) and defined daily dose (DDD) classification, data on outpatient use of all 14 antimycotics (12) and antifungals (2) for systemic use (ATC J02 and D01B, respectively), aggregated at the level of the active substance, were collected for 2007. Use was expressed in DDD (WHO ATC/DDD, version 2008) per 1000 inhabitants per day (DID). Only countries for which data on both J02 and D01B use were available were included in the analysis.

RESULTS

In 20 European countries (data for Cyprus and Estonia include hospital use), total outpatient systemic antimycotic and antifungal use varied by a factor of 6.7 between the country with the highest (3.03 DID in Belgium) and the country with the lowest (0.45 in Croatia) use. Terbinafine, ketoconazole, itraconazole and fluconazole represented >94% of the total outpatient antimycotic and antifungal use in all countries. Terbinafine use represented >50% of the total systemic antimycotic and antifungal use in 16 out of 20 countries (not in Croatia, Italy, Luxembourg and Bulgaria).

CONCLUSIONS

We present for the first time a standardized and validated data set of outpatient systemic antimycotic and antifungal use in Europe. Our study demonstrates a variation of antimycotic and antifungal use in Europe, as striking as that of antibiotic use. The ESAC data facilitate the auditing of antimycotic and antifungal prescribing, and the evaluation of the implementation of guidelines and public health policies to promote their judicious use.

Antibiotic prescribing over the last 16 years: fewer antibiotics but the spectrum is broadening

The purpose of this study was to quantify the antibiotics prescribed in the outpatient setting of all primary health care professionals in Catalonia during 1992-2007. We calculated prescribed defined daily doses per 1,000 inhabitants and day (DID) from data provided by the Catalonian Health Service. The antibiotics analysed belonged to the J01 group (ATC/DDD classification). The overall prescribing of antibacterials has decreased by 11.9% during this period (1992: 16.75 DID, 2007: 14.75 DID). During this 16-year period, an increase was observed for penicillins (from 46.1% in 1992 to 59.6% in 2007) and for quinolones (from 13.3% to 15.7%). The prescription of cephalosporins remained steady and, conversely, a decrease in macrolides was found (from 14.8% to 12.2%). The leading antibiotic prescribed in 2007 was amoxicillin plus clavulanic acid (5.15 DID), followed by amoxicillin (2.95 DID). The former has increased by 84.4% since 2002. Penicillin V prescribing reached a peak in 2007 with 0.034 DID. There has been a slight reduction in antibiotic prescription in this 16-year study, with an increase of penicillins, mainly at the expense of those of broader antibacterial spectrum. Awareness of the rational use of antibiotics is mandatory, basically aimed at reducing the overall prescribing of antibiotics and encouraging those with a narrower spectrum.

Decrease in macrolide resistance and clonal instability among Streptococcus pyogenes in Portugal

Macrolide resistance among Streptococcus pyogenes (group A streptococci) in Portugal was stable during 1998-2003, but a rapid inversion in the dominant phenotypes was noted in the same period, with a sharp decrease in the proportion of isolates presenting the MLS(B) phenotype and a concomitant increase in isolates presenting the M phenotype. The characterization of group A streptococci recovered during 2004-2006, which is reported here, revealed that resistance was not stable during this period and that the decline in erythromycin resistance observed during 2004-2006 was due to a decrease in the prevalence of isolates presenting the M phenotype, while the proportion of isolates expressing the MLS(B) phenotype remained stable. Characterization by emm typing, T serotyping, pulsed-field gel electrophoresis (PFGE) profiling and multilocus sequence typing revealed a very diverse population. Several of the major PFGE clusters identified had already been found in the 1998-2003 study period, but others were found for the first time, e.g. T11/emm11/ST403, carrying the erm(B) gene, and T3/13/emm3/ST315, carrying the mef(A) gene. The clone defined as T12/emm12/ST36, previously found to be associated with mef(A), was now found to be predominantly associated with erm(B). The clonal dynamics of macrolide-resistant group A streptococci emphasizes the importance of considering factors other than antibiotic consumption in explaining the prevalence of resistant isolates.

Antibiotic prescribing patterns in village health clinics across 10 provinces of Western China

OBJECTIVES

To explore antibiotic prescribing patterns in rural areas across 10 provinces of Western China and to compare the patterns among these provinces.

METHODS

About 20 125 prescriptions were collected from 680 primary health clinics in villages from 40 counties in 10 provinces of Western China. Percentage of prescriptions with antibiotics and number of antibiotics per 100 prescriptions were used as measurements of antibiotic utilization.

RESULTS

The percentage of prescriptions with antibiotics was 48.43 (range: 41.12-57.47) in the study areas. There were 49 kinds of antibiotics prescribed in total, and 17 of them accounted for 90% of all usage. The number of antibiotics per 100 prescriptions was 54.62 (range: 43.78-69.56).

CONCLUSIONS

The frequency and proportion of prescribed antibiotics in the rural areas of Western China are higher compared with the developed countries, and the patterns of antibiotic prescription differ greatly among provinces. The findings have important policy implications for recommendations on the utilization of antibiotics in China.

European Surveillance of Antimicrobial Consumption (ESAC): quality indicators for outpatient antibiotic use in Europe

BACKGROUND AND OBJECTIVE

Indicators to measure the quality of healthcare are increasingly used by healthcare professionals and policy makers. In the context of increasing antimicrobial resistance, this study aimed to develop valid drug-specific quality indicators for outpatient antibiotic use in Europe, derived from European Surveillance of Antimicrobial Consumption (ESAC) data.

METHODS

27 experts (15 countries), in a European Science Foundation workshop, built on the expertise within the European Drug Utilisation Research Group, the General Practice Respiratory Infections Network, the ESCMID Study Group on Primary Care Topics, the Belgian Antibiotic Policy Coordination Committee, the World Health Organization, ESAC, and other experts. A set of proposed indicators was developed using 1997-2003 ESAC data. Participants scored the relevance of each indicator to reducing antimicrobial resistance, patient health benefit, cost effectiveness and public health policy makers (scale: 1 (completely disagree) to 9 (completely agree)). The scores were processed according to the UCLA-RAND appropriateness method. Indicators were judged relevant if the median score was not in the 1-6 interval and if there was consensus (number of scores within the 1-3 interval was fewer than one third of the panel). From the relevant indicators providing overlapping information, the one with the highest scores was selected for the final set of quality indicators-values were updated with 2004 ESAC data.

RESULTS

22 participants (12 countries) completed scoring of a set of 22 proposed indicators. Nine were rated as relevant antibiotic prescribing indicators on all four dimensions; five were rated as relevant if only relevance to reducing antimicrobial resistance and public health policy makers was taken into account. A final set of 12 indicators was selected.

CONCLUSION

12 of the proposed ESAC-based quality indicators for outpatient antibiotic use in Europe have face validity and are potentially applicable. These indicators could be used to better describe antibiotic use in ambulatory care and assess the quality of national antibiotic prescribing patterns in Europe.

Validation of a confirmatory method for the determination of macrolides in liver and kidney animal tissues in accordance with the European Union regulation 2002/657/EC

This study proposes a simple multiresidue liquid chromatography-diode array detector (LC-DAD) method capable of determining seven macrolide antibiotics in samples of liver and kidney animals at concentrations lower than those allowed by current legislation. Samples were prepared by homogenizing the tissue with EDTA-McIlvaine's buffer and extracted with an Oasis HLB cartridge. The consumption of organic solvent during extraction was minimum. The analytes were detected by LC-DAD and also by liquid chromatography-mass spectrometry with electrospray ionization (LC-(ESI)MS). The method was specific, stable and robust enough for the required purposes. The DAD method was validated in accordance with the European Commission Decision 657/2002. Recovery data were also satisfactory with values higher than 67% for most macrolide antibiotics extracted from liver and kidney samples spiked at 200 microg/kg, the lowest MRL established for the macrolides studied. The relative standard deviations (RSD (%), (n=3)) were lower than 13% and 15% for intra-day and inter-day assays. The method was applied to investigate the occurrence of the studied macrolides in 31 beef and kidney animal samples. The results obtained by LC-DAD for positive samples were compared to those obtained by LC-(ESI)MS. Therefore, the method with simpler instrumentation than a LC-(ESI)MS can be used as a control method and the results of the validation process demonstrate that this method is suitable for application in a European Union program for monitoring residues of veterinary drugs.

Comparison of Outpatient Systemic Antibacterial Use in 2004 in the United States and 27 European Countries

The European Surveillance of Antimicrobial Consumption (ESAC) project collects data on antibacterial use in Europe, applying the Anatomic Therapeutic Chemical classification system and defined daily dose methodology, as recommended by the World Health Organization. Comparable data for the United States have been collected from IMS Health. The IMS Health sales data, processed according to ESAC methodology, suggest that outpatient antibacterial use in the United States is high (only 3 of 27 European countries used more) and is mainly characterized by a shift towards newer antibiotics.

Effect of azithromycin and clarithromycin therapy on pharyngeal carriage of macrolide-resistant streptococci in healthy volunteers: a randomised, double-blind, placebo-controlled study

BACKGROUND

Resistance to antibiotics is a major public-health problem, and studies that link antibiotic use and resistance have shown an association but not a causal effect. We used the macrolides azithromycin and clarithromycin to investigate the direct effect of antibiotic exposure on resistance in the oral streptococcal flora of healthy volunteers.

METHODS

Volunteers were treated with azithromycin (n=74), clarithromycin (74), or placebo (76) in a randomised, double-blind trial. Pharyngeal swabs were obtained before and after administration of study treatment through 180 days. The proportion of streptococci that were macrolide resistant was assessed and the molecular basis of any change in resistance investigated. Analyses were done on an intent-to-treat basis. This study is registered with ClinicalTrials.gov, number NCT00354952.

FINDINGS

The number of dropouts (n=20) was much the same in all groups until day 42; dropouts increased substantially at day 180 (105). Both macrolides significantly increased the proportion of macrolide-resistant streptococci compared with the placebo at all points studied, peaking at day 8 in the clarithromycin group (mean increase 50.0%, 95% CI 41.7-58.2; p<0.0001) and at day 4 in the azithromycin group (53.4%, 43.4-63.5; p<0.0001). The proportion of macrolide-resistant streptococci was higher after azithromycin treatment than after clarithromycin use, with the largest difference between the two groups at day 28 (17.4% difference, 9.2-25.6; p<0.0001). Use of clarithromycin, but not of azithromycin, selected for the erm(B) gene, which confers high-level macrolide resistance.

INTERPRETATION

This study shows that, notwithstanding the different outcomes of resistance selection, macrolide use is the single most important driver of the emergence of macrolide resistance in vivo. Physicians prescribing antibiotics should take into account the striking ecological side-effects of such antibiotics.

The use of erythromycin as a gastrointestinal prokinetic agent in adult critical care: benefits versus risks

Erythromycin A, the first macrolide, was introduced in the 1950s and after years of clinical experience it still remains a commonly relied upon antibiotic. In the past, pharmacodynamic characteristics of macrolides beyond antimicrobial action such as anti-inflammatory and immune-modulating properties have been of scientific and clinical interest. The function of erythromycin as a prokinetic agent has also been investigated for a range of gastrointestinal motility disorders and more recently within the context of critically ill patients. Prokinetic agents are drugs that increase contractile force and accelerate intraluminal transit. Whilst the anti-inflammatory action may be a desirable side effect to its antibiotic action, using erythromycin A merely for its prokinetic effect alone raises the concern about promoting emergence of macrolide resistance. The objectives of this review article are: (i) to briefly summarize the modes and epidemiology of macrolide resistance, particularly in respect to that found in the Streptococcus species (a potential reservoir for the dissemination of macrolide resistance on the critical care unit); (ii) to discuss in this context the evidence for conditions promoting bacterial resistance against macrolides; and (iii) to assess the potential clinical benefit of using erythromycin A as a prokinetic versus the risks of promoting emergence of macrolide resistance in the clinical setting. We conclude, that in view of the growing weight of evidence demonstrating the potential epidemiological impact of the increased use of macrolides upon the spread of resistance, versus a lack of sufficient and convincing evidence that erythromycin A is a superior prokinetic agent to potential alternatives in the critically ill patient population, at this stage we do not advocate the use of erythromycin A as a prokinetic agent in critically ill patients unless they have failed all other treatment for impaired gastrointestinal dysmotility and are intolerant of metoclopramide. Further large and methodologically robust studies are needed to ascertain the effectiveness of erythromycin A and other alternative agents in the critically ill.

How to fight antimicrobial resistance

Antimicrobial misuse results in the development of resistance and superbugs. Over recent decades, resistance has been increasing despite continuing efforts to control it, resulting in increased mortality and cost. Many authorities have proposed local, regional and national guidelines to fight against this phenomenon, and the usefulness of these programmes has been evaluated. Multifaceted intervention seems to be the most efficient method to control antimicrobial resistance. Monitoring of bacterial resistance and antibiotic use is essential, and the methodology has now been homogenized. The implementation of guidelines and infection control measures does not control antimicrobial resistance and needs to be reinforced by associated measures. Educational programmes and rotation policies have not been evaluated sufficiently in the literature. Combination antimicrobial therapy is inefficient in controlling antimicrobial resistance.

M.SpyI, a DNA methyltransferase encoded on a mefA chimeric element, modifies the genome of Streptococcus pyogenes

While screening the clonality of Streptococcus pyogenes isolates from an outbreak of erythromycin-resistant pharyngitis in Pittsburgh, PA, we found a correlation between the presence of the chimeric element Phi10394.4 (carrying the macrolide efflux gene, mefA) and genomic DNA being resistant to cleavage by SmaI restriction endonuclease. A search of the open reading frames in Phi10394.4 identified a putative type II restriction-modification (R-M) cassette containing a cytosine methyltransferase gene (spyIM). Heterologous expression of the cloned spyIM gene, as well as allelic-replacement experiments, showed that the action of this methyltransferase (M.SpyI) was responsible for the inhibition of SmaI digestion of genomic DNA in the Phi10394.4-containing isolates. Analysis of the methylation patterns of streptococcal genomic DNA from spyIM-positive strains, a spyIM deletion mutant, and a spyIM-negative strain determined that M.SpyI specifically recognized and methylated the DNA sequence to generate 5'-C(m)CNGG. To our knowledge, this is the first methyltransferase gene from S. pyogenes to be cloned and to have its activity characterized. These results reveal why pulsed field gel electrophoresis analysis of SmaI-digested genomic DNA cannot be used to analyze the clonality of some streptococci containing Phi10394.4 and may explain the inability of previous epidemiological studies to use SmaI to analyze DNAs from macrolide-resistant streptococci. The presence of the SpyI R-M cassette in Phi10394.4 could impart a selective advantage to host strain survival and may provide another explanation for the observed increase in macrolide-resistant streptococci.

European Surveillance of Antimicrobial Consumption (ESAC): outpatient antibiotic use in Europe

BACKGROUND

The ESAC project, granted by DG SANCO of the European Commission, is an international network of surveillance systems, aiming to collect comparable and reliable data on antibiotic use in Europe. Data on outpatient antibiotic use were collected from 34 countries using the ATC/DDD methodology.

METHODS

For the period 1997-2003, data on outpatient use of systemic antibiotics aggregated at the level of the active substance were collected and expressed in DDD (WHO, version 2004) per 1000 inhabitants per day (DID). Outpatient antibiotic (ATC J01) use in 25 European countries, able to deliver valid data, was analysed.

RESULTS

Total outpatient antibiotic use in 2003 varied by a factor of 3 between the country with the highest (31.4 DID in Greece) and the country with the lowest (9.8 DID in the Netherlands) use. General use patterns in individual countries as well as trends during the period 1997-2003 are described in this paper, while major antibiotic classes (penicillins, cephalosporins, macrolides/lincosamides/streptogramins and quinolones) will be analysed in detail in separate papers.

CONCLUSION

The ESAC project established for the first time a credible alternative to industry sources for the collection of internationally comparable data on antibiotic use in Europe, based on cooperation between regulatory authorities, scientific societies, health insurers and professional organizations. These data provide a tool for assessing public health strategies aiming to optimize antibiotic prescribing.