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PubMed2006

External quality assurance system for antibiotic resistance in bacteria of animal origin in Europe (ARBAO-II), 2003.

Initiated in 2003 by the European Union, ARBAO-II aims to establish a monitoring of antimicrobial susceptibility among the veterinary laboratories in all European countries based on validated methodologies. This includes an external quality control system for the most important bacterial pathogens. In 2003 two trials were performed. The first on Salmonella and Escherichia coli involved 31 laboratories in 18 countries and the second on Staphylococcus and Streptococcus included 22 laboratories in 15 countries. For the E. coli strains, 92.8% of the results complied with the reference MICs, for Salmonella 93.7%, for Streptococcus 80.4% and for Staphylococcus 93.1%. Most problems were observed when testing florfenicol (79.2% correct), gentamicin (84.2%) and amoxicillin + cl (84.9%) in E. coli; streptomycin in Salmonella (62.5%); gentamicin (56.7%), lincomycin (71.4%), clindamycin (75.4%), TMP + sulfonamides (75.7%) and chloramphenicol (78.5%) in Streptococcus; erythromycin (81.5%) and oxacillin (78.2.5%) in Staphylococcus. A few laboratories caused most deviations. However, there was no correlation between good performance for one bacterial group and good performance for other groups. This study showed that most laboratories are capable of performing correct susceptibility testing for E. coli and Salmonella, even though performance of some laboratories can be improved, and that some problems exist for Staphylococcus and Streptococcus. This clearly shows the need for continuous harmonisation of methodologies within the EU.

Animals↗
PubMed2003

European survey of vancomycin-resistant enterococci in at-risk hospital wards and in vitro susceptibility testing of ramoplanin against these isolates.

A survey in eight European countries, including 13 hospitals, of vancomycin-resistant enterococci (VRE) in at-risk hospital wards (such as the ICU and the haematology ward) was performed in 2001, and the in vitro susceptibility of the isolates ramoplanin and other drugs was tested. A total of 1314 non-duplicate clinical enterococcal isolates were collected, and 38 (2.9%) were vancomycin resistant: 27 Enterococcus faecium and 11 Enterococcus faecalis; 35 VanA and three VanB phenotypes. Rates of VRE among clinical enterococcal isolates varied between 0 and 1.7% for the participating countries, except the UK (10.4%) and Italy (19.6%). One hundred and twenty-three (3.5%) VRE were found among 3499 stool samples tested for the presence of these organisms: 111 (3.2%) E. faecium and 12 (0.3%) E. faecalis; 114 (3.3%) VanA and nine (0.3%) VanB phenotypes. Rates of intestinal colonization with VRE varied between 0 and 1.2% for the participating countries, except Italy (7.5%) and the UK (32.6%). In vitro susceptibility testing showed that the Italian and UK VRE are multi-resistant (including resistance to ampicillin and high-level resistance to gentamicin and streptomycin), and that ramoplanin was active against all strains of VRE, with an MIC90 of 0.5 mg/L for clinical isolates. Pulsed-field gel electrophoresis showed that the high prevalence of VRE in the Italian and UK centres was related to the monoclonal emergence and spread of three centre-specific clones. This survey suggests that in some centres in Europe, a similar situation may be encountered to that in the USA (monoclonal spread of multi-resistant VRE in at-risk wards).

Anti-Bacterial Agents↗
PubMed2006

European Committee on Antimicrobial Susceptibility Testing (EUCAST) Technical Notes on antimicrobial susceptibility testing.

The main objectives of the European Committee on Antimicrobial Susceptibility Testing (EUCAST) are to harmonise breakpoints for antimicrobial agents in Europe, and to act as the breakpoint committee for the European Medicines Agency (EMEA) during the registration of new antimicrobial agents. Detailed EUCAST procedures for harmonising and setting breakpoints for antimicrobial agents are available on the EUCAST website. Beginning with the current issue, a series of EUCAST Technical Notes will be published in CMI, based on the rationale documents produced by EUCAST for each of the antimicrobial agents studied, with the aim of highlighting important background information underlying decisions on breakpoints made by EUCAST.

Advisory Committees↗
PubMed1992

Standardized susceptibility testing of fluconazole: an international collaborative study.

An international collaborative study of broth dilution (MIC) and disk diffusion susceptibility testing of fluconazole was conducted by using a chemically defined medium (High-Resolution Antifungal Assay Medium; Oxoid Ltd., Basingstoke, United Kingdom) and standard test methods performed in eight reference laboratories. Ten yeast isolates were tested by each test method in duplicate on each of 3 separate days. The intralaboratory reproducibility of the MIC test was excellent; 95.7% of the replicate tests (n = 220) were within 2 doubling dilutions of the other values in the set for the eight laboratories. The intralaboratory reproducibility of the disk test was also good, with 91% of the replicate tests (n = 234) agreeing with each other within an arbitrarily chosen value of 4 mm. Interlaboratory agreement of MIC test results was acceptable, with 84% of the MICs agreeing within 2 doubling dilutions. In contrast, the interlaboratory agreement of the disk test was not good, with only 59% of test results agreeing within 4 mm. Comparison of the rank order of MICs obtained in each laboratory with the reference rank order gave an agreement of 70 to 80% (median, 80%) with the MIC test and 70 to 90% (median, 80%) with the disk test. These preliminary results are encouraging for the development of standardized testing methods for testing fluconazole.

Culture Media↗
PubMed2005

Antimicrobial spectrum and potency of dalbavancin tested against clinical isolates from Europe and North America (2003): initial results from an international surveillance protocol.

Dalbavancin is a bactericidal dimethylaminopropyl amide glycopeptide derivative possessing an extended serum elimination half-life in humans that allows once-weekly dosing for the therapy of Gram-positive infections. Strains from this baseline surveillance protocol in North America (NA; USA and Canada) and Europe (EU, 14 countries) were sampled in 2003. A total of 7,765 Gram-positive isolates (3,695 from NA and 4,070 from EU) were tested by reference broth microdilution methods against dalbavancin and 10 comparator agents. Species were analyzed separately by resistance phenotypes such as methicillin- (oxacillin-) resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE) and penicillin-resistant Streptococcus pneumoniae. Dalbavancin and other glycopeptides were very active against staphylococci (n=4648) with dalbavancin being 16- to 32-fold more potent than vancomycin (MIC90, 0.06 versus 2 mg/L). MRSA rates were greater (31.6%) in NA than in EU (26.1%). Quinupristin/dalfopristin resistance (MIC, > or = 2 mg/L; 0.1-0.5%) was documented more often in EU compared to NA. Dalbavancin (MIC50, 0.03-0.06 mg/L) was active against enterococci, except VanA resistance phenotypes. VRE rates were lower in EU (8.3%) then in NA (35.9%) from this resistance-enhanced enterococcal collection. Streptococci (dalbavancin MIC90, 0.016-0.03 mg/L) were generally most susceptible to glycopeptides (100.0%), quinupristin/dalfopristin (98.6-100.0%) and linezolid (100.0%); but dalbavancin was 16-fold more active than comparators. All vancomycin-susceptible enterococci and > 90% of vanB VRE had dalbavancin MIC values at < or = 1 mg/L,but vanA VRE strains had dalbavancin MIC results ranging from 0.06 to > 8 mg/L (median MIC, > or = 8 mg/L). Dalbavancin MIC values were not adversely influenced by geographic region or resistance phenotype (except vanA VRE). Infrequently isolated Gram-positive organisms such as Bacillus spp. (MIC90, 0.12 mg/L), Corynebacterium spp. (MIC90, 0.12 mg/L), Listeria monocytogenes (MIC90, 0.25 mg/L) and Micrococcus spp. (MIC90, 0.03 mg/L) were very susceptible to dalbavancin. In conclusion, these 2003 baseline resistance surveillance findings confirm the potent dalbavancin activity compared to several comparator agents against important Gram-positive pathogens. This high volume international survey indicates potential therapeutic roles for dalbavancin against many troublesome resistant Gram-positive phenotypes.

Anti-Bacterial Agents↗
PubMed2001

Antimicrobial resistance: standardisation and harmonisation of laboratory methodologies for the detection and quantification of antimicrobial resistance.

The Ad hoc Group of experts on antimicrobial resistance of the Office International des Epizooties has developed a guideline on the standardisation and harmonisation of laboratory methodologies used for the detection and quantification of antimicrobial resistance. The existing methods (disk diffusion [including concentration gradient strips], agar dilution and broth dilution) are reviewed, including a comparison of their advantages and disadvantages. The definitions of resistance characteristics of bacteria (susceptible, intermediate and resistant) are addressed and the criteria for the establishment of breakpoints are discussed. Due consideration has to be given to these aspects in the interpretation and comparison of resistance monitoring or surveillance data. The use of validated laboratory methods and the establishment of quality assurance (internal and external) for microbiological laboratory work and the reporting of quantitative test results is recommended. Equivalence of different methods and laboratory test results is also recommended to be established by external proficiency testing, which should be achieved by the means of a reference laboratory system. This approach allows the comparison of test results obtained using different methods generated by laboratories in different countries.

Animals↗
PubMed2005

Antifungal susceptibility testing methods.

The number of systemically active antifungal agents has increased dramatically in recent years in response to the challenge of invasive mycoses. Additional work is needed to better understand the mechanisms of action of these agents as well as the mechanisms of resistance expressed by the fungal pathogens. Antifungal susceptibility testing has been standardized and refined and now may be considered to play an important role in the management of invasive mycoses. More work is needed to optimize the methods for testing new antifungal agents and for testing pathogens other than Candida. The ongoing efforts and international collaborations designed to address these issues will provide important information that will improve the management of serious fungal infections.

Antifungal Agents↗
PubMed2002

Role of electronic data exchange in an international outbreak caused by Salmonella enterica serotype Typhimurium DT204b.

From July through September 2000, patients in five European countries were infected with a multidrug-resistant strain of Salmonella Typhimurium DT204b. Epidemiologic investigations were facilitated by the transmission of electronic images (Tagged Image Files) of pulsed-field gel electrophoresis profiles. This investigation highlights the importance of standardized protocols for molecular typing in international outbreaks of foodborne disease.

Computer Communication Networks↗
PubMed2005

Integrating Escherichia coli antimicrobial susceptibility data from multiple surveillance programs.

Collaboration between networks presents opportunities to increase analytical power and cross-validate findings. Multivariate analyses of 2 large, international datasets (MYSTIC and SENTRY) from the Global Advisory on Antibiotic Resistance Data program explored temporal, geographic, and demographic trends in Escherichia coli resistance from 1997 to 2001. Elevated rates of nonsusceptibility were seen in Latin America, southern Europe, and the western Pacific, and lower rates were seen in North America. For most antimicrobial drugs considered, nonsusceptibility was higher in isolates from men, older patients, and intensive care unit patients. Nonsusceptibility to ciprofloxacin was higher in younger patients, rose with time, and was not associated with intensive care unit status. In univariate analyses, estimates of nonsusceptibility from MYSTIC were consistently higher than those from SENTRY, but these differences disappeared in multivariate analyses, which supports the epidemiologic relevance of findings from the 2 programs, despite differences in surveillance strategies.

Anti-Bacterial Agents↗
PubMedDate not supplied

Two rapid methods for detection of Escherichia coli exceeding 10(4)/g action levels: precollaborative study.

The current AOAC Method 966.24 for enumeration of Escherichia coli in foods uses a most probable number (MPN) procedure with extensive confirmation steps. Two new methods based on membrane filtration (MF) were compared to the MPN reference method for detection of high levels of E. coli in 5 food types, some of which represent categories for which the U.S. Food and Drug Administration (FDA) mandates additional testing if an action level of 10(4)/g E. coli is exceeded. Ground beef, which is not FDA regulated, was also tested. The 5 food types were all inoculated at 3 levels: 10(2)/g, > or = 10(4)/g, and > or = 10(5)/g E. coli. An MF protocol using either m-ColiBlue24 (CB) or lauryl sulfate tryptose plus BCIG (LST/BCIG) was an effective potential alternative to the reference method. Sensitivity and specificity for both CB and LST/BCIG were 98 and 100%, respectively. Agreement between MPN and both CB and LST/BCIG was 98%. The 2 proposed methods allow completion of both presumptive and confirmatory steps in 1-3 days, whereas the reference method requires as many as 11 days. Exclusivity testing with 50 non-E. coli strains indicated 100% were correctly ruled out by the proposed protocols. Inclusivity testing was used to determine whether typical results were obtained after incubation of E. coli cultures on CB or LST/BCIG for 24 h. Of 50 E. coli strains tested, 100% yielded typical results after incubation on CB, and 98% yielded typical results after incubation on LST/BCIG.

Colony Count, Microbial↗
PubMedDate not supplied

Modification to the AOAC Sporicidal Activity of Disinfectants Test (Method 966.04): collaborative study.

In an effort to improve AOAC Method 966.04, the Sporicidal Activity of Disinfectants Test, selected modifications to the procedure were evaluated in a collaborative study. Method 966.04 is used to generate efficacy data to support the product registration of sporicides and sterilants. The method is a carrier-based test that provides a qualitative measure of product efficacy against spores of Bacillus subtilis and Clostridium sporogenes. The use of garden soil extract and the lack of standard procedures for the enumeration of spores and neutralization of the test chemicals have been considered problematic for many years. The proposed modifications were limited to the B. subtilis and hard surface carrier (porcelain penicylinder) components of the method. The study included the evaluation of a replacement for soil extract nutrient broth and an establishment of a minimum spore titer per carrier, both considered crucial for the improvement and utilization of the method. Additionally, an alternative hard surface material and a neutralization confirmation procedure were evaluated. To determine the equivalence of the proposed alternatives to the standard method, 3 medium/carrier combinations, (1) soil extract nutrient broth/porcelain carrier (current method), (2) nutrient agar amended with 5 microg/mL manganese sulfate/porcelain carrier, and (3) nutrient agar amended with 5 microg/mL manganese sulfate/stainless steel carrier were analyzed for carrier counts, HCI resistance, efficacy, quantitative efficacy, and spore wash-off. The test chemicals used in the study represent 3 chemical classes and are commercially available antimicrobial liquid products: sodium hypochlorite (bleach), glutaraldehyde, and a combination of peracetic acid and hydrogen peroxide. Four laboratories participated in the study. The results of the spore titer per carrier, HCI resistance, efficacy, and wash-off studies demonstrate that amended nutrient agar in conjunction with the porcelain is comparable to the current method, soil extract nutrient broth/porcelain. The nutrient agar method is simple, inexpensive, reproducible, and provides an ample supply of high quality spores. Due to the current use of porcelain carriers for testing C. sporogenes, it is advisable to retain the use of porcelain carriers until stainless steel can be evaluated as a replacement carrier material for Clostridium. The evaluation of stainless steel for Clostridium has been initiated by the Study Director. Study Director recommendations for First Action revisions are provided in a modified method.

Bacillus subtilis↗
PubMed1987

Worldwide study of cefoperazone susceptibility.

In vitro susceptibility to cefoperazone of more than one million clinical aerobic bacterial isolates was evaluated in 369 hospitals in Japan, the United States, Canada, France, Austria, and Hungary. Standard versions of the disk diffusion method were used according to interpretive criteria approved in the respective countries, and comparisons were made among the countries and among various body sites. Susceptibility of organisms varied little within most species among the countries. Minor differences in methodology and in interpretive criteria may explain some of the variations observed among countries and hospitals. The susceptibility of key pathogens to cefoperazone among countries ranged from 91% to 98% for Escherichia coli, 73% to 91% for Pseudomonas aeruginosa, 90% to 95% for Klebsiella pneumoniae, 73% to 92% for Enterobacter cloacae, 74% to 92% for Staphylococcus aureus, and 91% to 97% for Proteus mirabilis. Susceptibility of isolates from the urinary tract did not vary markedly from that in other body sites.

Cefoperazone↗