PubMed Health⌕ Search

Biomedical subjects

G Kahlmeter

Publications and source records attributed to G Kahlmeter.

At least 19 recordsLinked to original sources
PubMed2006

Phenotypic detection of methicillin resistance in Staphylococcus aureus by disk diffusion testing and Etest on Mueller-Hinton agar.

Cefoxitin is increasingly recommended for detection of methicillin resistance in Staphylococcus aureus (MRSA) when using disk diffusion testing. In this study, 95 mecA-negative S. aureus isolates and a highly genetically diverse collection of mecA-positive S. aureus types (n=50) were used to investigate the influence of technical factors such as disk potency, incubation time, and temperature on Mueller-Hinton agar. The use of cefoxitin MIC testing by Etest for the same purpose was investigated under similar conditions. For disk diffusion, the accuracy was high at both 35 degrees C and 36 degrees C using overnight incubation, while incubation at 30 degrees C or 37 degrees C was associated with slightly lower accuracy. Increasing incubation times from 18 to 24 h did not improve accuracy at either temperature. Cefoxitin Etest MICs for mecA-positive strains were 6 mg/liter or higher, while cefoxitin Etest MICs for mecA-negative strains were 4 mg/liter, corresponding to S>or=22 mm and R or=17 mm and R<or=16 mm for the 10-microg cefoxitin disk. These criteria resulted in only one mecA-positive isolate being misclassified as susceptible.

Anti-Bacterial Agents↗
PubMed2006

Staphylococcus aureus resistant to fusidic acid among Swedish children: a follow-up study.

We previously described the epidemic spread of a fusidic acid resistant clone of Staphylococcus aureus among children with bullous impetigo throughout Sweden 1. In this follow-up study we present data showing that Swedish clinicians in 2002 drastically reduced prescriptions of fusidic acid ointments, probably in response to the epidemic. Furthermore, we show that the fusidic acid resistant clone which dominated in 2001 is still the most prevalent fusidic acid resistant S. aureus in the population. The epidemic which reached its peak in 2002 is now clearly declining.

Adolescent↗
PubMed2006

Statistical characterisation of bacterial wild-type MIC value distributions and the determination of epidemiological cut-off values.

MIC distribution data were obtained from a variety of international sources, and pooled after selection by a defined criterion. Sixty-seven of these datasets were subjected to a range of statistical goodness-of-fit tests. The log-normal distribution was selected for subsequent modelling. Cumulative counts of MIC distribution data were fitted to the cumulative log-normal distribution using non-linear least squares regression for a range of data subsets from each antibiotic-bacterium combination. Estimated parameters in the regression were the number of isolates in the subset, and (the log(2) values of) the mean and standard deviation. Optimum fits for the cumulative log-normal curve were then used to determine the wild-type MIC range, determined by calculating the MICs associated with the lower and upper 0.1% of the distribution, rounding to the nearest two-fold dilution, and calculating the probabilities of values higher and lower than these values. When plotted logarithmically, histograms of MIC frequencies appeared normal (Gaussian), but standard goodness-of-fit tests showed that the two-fold dilution grouping of MICs fits poorly to a log-normal distribution, whereas non-linear regression gave good fits to population (histogram) log-normal distributions of log(2) MIC frequencies, and even better fits to log-normal cumulative distributions. Optimum fits were found when the difference between the estimated and true number of isolates in the fitted subset was minimal. Sixteen antibiotic-bacterium datasets were fitted using this technique, and the log(2) values of the means and standard deviations were used to determine the 0.1% and 99.9% wild-type cut-off values. When rounded to the nearest two-fold dilution, > or = 98.5% of MIC values fall within the cut-off value range. Non-linear regression fitting to a cumulative log-normal distribution is a novel and effective method for modelling MIC distributions and quantifying wild-type MIC ranges.

Anti-Infective 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↗
PubMed2005

Diversity among 2481 Escherichia coli from women with community-acquired lower urinary tract infections in 17 countries.

OBJECTIVES: In the recently published ECO.SENS survey, the antimicrobial susceptibility of Escherichia coli from urinary tract infections in women in 16 European countries and Canada was investigated. This study reports the diversity among these E. coli. METHODS: The 2481 E. coli, typed with the PhenePlate (PhP) System utilizing the dynamics and end result of 11 biochemical reactions in a microplate system, were clustered and the Simpson's index of diversity calculated. RESULTS: Seventy-four Common PhP Types (CT) comprising 2067 isolates and 414 Single Types (Si) were identified. Of these, 916 isolates (37%) belonged to one of the four most frequent CT (arbitrarily numbered CT48, 10, 26 and 20). CT48 with 400 isolates and 11 different susceptibility patterns, was widely disseminated across Europe and Canada and was the most frequent type in 13 countries and the second most frequent in the remaining four countries. Sixty-four per cent of the E. coli were susceptible to all eight investigated antimicrobials (CT48: 73%, CT10: 77%, CT26: 62% and CT20: 37%). Forty-six different susceptibility patterns were seen, the three most common being isolated resistance to ampicillin, resistance to ampicillin and trimethoprim, and isolated resistance to trimethoprim. Multiresistance, here defined as resistance to four or more of the investigated antibiotics, was distributed among E. coli belonging to several PhP types. CONCLUSIONS: There was no obvious correlation between the phenotypes identified with the PhP System and the susceptibility pattern. The data did not indicate clonal dissemination within or between countries as a major reason for differences in antimicrobial resistance rates.

Adult↗
PubMed2005

Evaluation of cefoxitin 5 and 10 microg discs for the detection of methicillin resistance in staphylococci.

OBJECTIVE: To evaluate cefoxitin 5 and 10 microg discs for detection of methicillin resistance in staphylococci. METHODS: Six hundred and forty-one Staphylococcus aureus (261 mecA-negative and 380 mecA-positive) and 344 coagulase-negative staphylococci (CoNS) (132 mecA-negative and 212 mecA-positive) were investigated. The CoNS represented nine species, Staphylococcus epidermidis being the most frequent (n = 231). All isolates were tested using semi-confluent growth on Iso-Sensitest agar (ISA), and Mueller-Hinton agar (MH) using a 5 and a 10 microg cefoxitin disc and overnight incubation in ambient air at 35-37 degrees C. RESULTS: For S. aureus, both cefoxitin discs performed with high accuracy on both media. The sensitivity and specificity for the following proposed interpretive zone diameters were: ISA 5 microg, R < 14 mm (99.5% and 98.1%); ISA 10 microg, R < 22 mm (99.5% and 98.1%); MH 5 microg, R < 12 mm (99.7% and 98.1%); and MH 10 microg, R < 18 mm (99.5% and 98.9%), respectively. All four variants were superior to oxacillin using the former SRGA methodology. In CoNS, a substantial overlap was seen for all variants. However, by avoiding primary interpretation in the overlapping interval, highly accurate results could be obtained for 81%, 80%, 91% and 97% of the isolates, respectively. CONCLUSION: For S. aureus, cefoxitin 5 and 10 microg discs performed with high accuracy on both ISA and MH using semi-confluent growth and standard incubation conditions. With the introduction of a defined interval in which primary interpretation should be avoided, the method could also be used for CoNS.

Cefoxitin↗
PubMed2004

Antimicrobial resistance in Escherichia coli in urine samples from children and adults: a 12 year analysis.

AIM: To investigate the distribution and antimicrobial resistance in urinary tract pathogens, primarily Escherichia coli, in two age groups, children < or = 2 y and adults 18-50 y, over a period of 12 y. METHODS: From the database of the microbiological laboratory all urinary tract culture data were extracted and structured according to date, patient age, bacteriological findings, antimicrobial susceptibility results and sample type. Statistical longitudinal analysis of bacteriological findings and antimicrobial resistance trends in the two age groups were performed. RESULTS: Statistical significance was obtained for the following results. Escherichia coli was the most common pathogen in both age groups and irrespective of sample type. In E. coli resistance to ampicillin and trimethoprim was higher in children than in adults and increased over time in both age groups. Resistance to fluoroquinolones was higher in adults than in children and increased over time in both groups. Resistance to pivmecillinam, cefadroxil and nitrofurantoin was below 2% in 2001 in both age groups. CONCLUSION: The steadily increasing and now high E. coli resistance levels in children to ampicillin and trimethoprim render empirical therapy with these drugs doubtful. The stable and low levels of resistance to pivmecillinam, cefadroxil and nitrofurantoin (< 2% in 2001) make these drugs reasonable alternatives in uncomplicated lower urinary tract infections.

Adolescent↗
PubMed2004

European recommendations for antimicrobial resistance surveillance.

The problem of antimicrobial resistance surveillance in Europe has been debated extensively in many excellent documents issued by national committees that often assume the value of national guidelines. However, a comprehensive document addressing the whole matter from a European perspective, as well as reviewing its present status and drafting future perspectives, has been lacking. The present recommendations have been produced by the ESCMID Study Group for Antimicrobial Resistance Surveillance (ESGARS) through a consensus process involving all members of the Study Group. The recommendations focus on the detection of bacterial resistance and its reporting to clinicians, public health officers and a wider-and ever-increasing-audience. The leading concept is that the basis for resistance monitoring is microbiological diagnostics. The prerequisites for resistance monitoring are findings of adequate quality and quantity, which have been recorded properly and evaluated correctly. Different types of surveillance studies should fulfil different requirements with regard to data collection and reporting, the expected use of data, and the prerequisites for networking such activities. To generate relevant indicators, bacterial resistance data should be reported using adequate denominators and stratification. Reporting of antimicrobial resistance data is necessary for selection of empirical therapy at the local level, for assessing the scale of the resistance problem at the local, national or international levels, for monitoring changes in resistance rates, and for detecting the emergence and spread of new resistances types. Any type of surveillance study should conclude, where appropriate, with a proposal for intervention based on the data obtained.

Anti-Bacterial Agents↗
PubMed2003

Non-hospital antimicrobial usage and resistance in community-acquired Escherichia coli urinary tract infection.

OBJECTIVES: To investigate the correlation between non-hospital antimicrobial consumption and resistance. METHODS: Information on the non-hospital sales of antimicrobials from 14 European countries in 1997 and 2000 was compared with the antimicrobial resistance profiles of Escherichia coli isolated from women with community-acquired urinary tract infection in the same countries in 1999/2000. RESULTS: There was no statistically significant correlation between the consumption of and resistance to co-amoxiclav, cefadroxil, fosfomycin, mecillinam, sulfamethoxazole, trimethoprim or trimethoprim-sulfamethoxazole. On the other hand, there were statistically significant correlations between consumption of broad-spectrum penicillins and quinolones in 1997 and 2000 and resistance to ciprofloxacin (P range 0.0005-0.0045) and nalidixic acid (P range 0.0013-0.0049). Total antimicrobial consumption in 1997 was significantly correlated to ciprofloxacin (P=0.0009) and nalidixic acid (P=0.0018) resistance, and there were significant relationships between quinolone consumption in both years and resistance to gentamicin (P range 0.0029-0.0043) and nitrofurantoin (P range 0.0003-0.0007). E. coli with multiple antimicrobial resistance were significantly more common in countries with high total antimicrobial consumption. CONCLUSIONS: Owing to the frequent presence of many possible confounding factors, antimicrobial resistance to one drug does not always correlate well to the consumption of the same drug or closely related drugs. This study showed that the degree of antimicrobial consumption was significantly correlated to the incidence of multidrug-resistant E. coli.

Adolescent↗
PubMed2003

Evaluation of a cefoxitin 30 microg disc on Iso-Sensitest agar for detection of methicillin-resistant Staphylococcus aureus.

OBJECTIVES: To evaluate the performance of a cefoxitin 30 microg disc on Iso-Sensitest agar, using a semi-confluent inoculum and overnight incubation at 35-36 degrees C, for detection of methicillin-resistant Staphylococcus aureus (MRSA). METHODS: A total of 457 S. aureus, including 190 MRSA of several defined PFGE types and a number of low-level resistant isolates, were tested with a cefoxitin 30 microg disc on Iso-Sensitest agar, using a semi-confluent inoculum and overnight incubation at 35-36 degrees C. This method was compared with the standard SRGA (Swedish Reference Group for Antibiotics) method (oxacillin 1 microg disc on Iso-Sensitest agar supplemented with 5% defibrinated horse blood, confluent growth and 24 h incubation in ambient air at 30 degrees C). RESULTS: The cefoxitin method was excellent, with a sensitivity of 100% and a specificity of 99% using an interpretative zone diameter of S > or = 29 mm and R < 29 mm. Its performance was much better than the SRGA method, which with this collection of difficult strains had a sensitivity of only 78% using the current breakpoint of S > or = 12 mm. CONCLUSION: We suggest that the cefoxitin method should replace that currently recommended by the SRGA for the detection of MRSA, and that it would fit well into BSAC methodology.

Agar↗
PubMed2003

Prevalence and antimicrobial susceptibility of pathogens in uncomplicated cystitis in Europe. The ECO.SENS study.

The ECO.SENS study investigated the prevalence and antimicrobial susceptibility of pathogens causing community-acquired acute uncomplicated urinary tract infections (UTIs) in 4734 women aged 18-65 years presenting with symptoms of acute UTI, at 252 community healthcare centres in 16 countries in Europe plus Canada. Resistance in Escherichia coli occurred most frequently to ampicillin (30%) and sulphonamides (29%), followed by trimethoprim (15%), trimethoprim/sulphamethoxazole (14%) and nalidixic acid (5%) but was low to co-amoxiclav, mecillinam, cefadroxil, nitrofurantoin, fosfomycin, gentamicin and ciprofloxacin, all at<3%. Consumption of antibiotics in 1997 varied more than 4-fold within Europe and from 9 to 37 DDD/1000 inhabitants/day, the consumption being highest in Southern Europe. The consumption of broad-spectrum penicillins correlated with resistance to ampicillin and there was a clear correlation between quinolone consumption and resistance to ciprofloxacin and nalidixic acid. The 4-fold difference in antibiotic consumption within Europe and the correlation to resistance emphasises the importance of controlling antibiotic usage.

Adolescent↗
PubMed2003

A new method for normalized interpretation of antimicrobial resistance from disk test results for comparative purposes.

OBJECTIVE: To evaluate a calibration method for disk diffusion antibiotic susceptibility tests, using zone diameter values generated in the individual laboratory as the internal calibrator for combinations of antibiotic and bacterial species. METHODS: The high-zone side of zone histogram distributions was first analyzed by moving averages to determine the peak position of the susceptible population. The accumulated percentages of isolates for the high zone diameter values were calculated and converted into probit values. The normal distribution of the ideal population of susceptible strains was then determined by using the least-squares method for probit values against zone diameters, and the ideal population was thereby defined, including mean and standard deviation. Zone diameter values were obtained from laboratories at the Karolinska Hospital (KS) and Växjö Hospital (VX), and from two laboratories (LabA, LabB) in Argentina. The method relies on well standardized disk tests, but is independent of differences in MIC limits and zone breakpoints, and does not require the use of reference strains. Resistance was tentatively set at below 3 SD from the calculated, ideal mean zone diameter of the susceptible population. RESULTS: The method, called normalized interpretation of antimicrobial resistance, was tested on results from the KS and VX clinical microbiology laboratories, using the disk diffusion method for antimicrobial susceptibility tests, and for two bacterial species, Staphylococcus aureus and Escherichia coli. In total, 114 217 test results were included for the clinical isolates, and 3582 test results for control strains. The methodology at KS and VX followed the standard of the Swedish Reference Group for Antibiotics (SRGA). Zone diameter histograms for control strains were first analyzed to validate the procedure, and a comparison of actual means with the calculated means showed a correlation coefficient of r = 0.998. Results for clinical isolates at the two laboratories showed an excellent agreement for 54 of 57 combinations of antibiotic and bacterial species between normalized interpretations and the interpretations given by the laboratories. There were difficulties with E. coli and mecillinam, and S. aureus and tetracycline and rifampicin. The method was also tested on results from two laboratories using the NCCLS standard, and preliminary results showed very good agreement with quality-controlled laboratory interpretations. CONCLUSIONS: The normalized resistance interpretation offers a new approach to comparative surveillance studies whereby the inhibition zone diameter results from disk tests in clinical laboratories can be used for calibration of the test.

Anti-Bacterial Agents↗
PubMed2003

An international survey of the antimicrobial susceptibility of pathogens from uncomplicated urinary tract infections: the ECO.SENS Project.

The ECO.SENS study is the first international survey to investigate the prevalence and susceptibility of pathogens causing community-acquired acute uncomplicated urinary tract infections (UTIs). Midstream urine samples were taken for culture and for testing for the presence of leucocytes from 4734 women not older than 65 years presenting with symptoms of acute UTI at 252 community health care centres in 17 countries. Recognized urinary tract pathogens were identified and the susceptibility to 12 antimicrobials determined. Pathogens were present in 3278 (69.2%) patients, Escherichia coli accounting for 77.0% of isolates. In E. coli, 42% of the isolates were resistant to one or more of the 12 antimicrobial drugs investigated. Resistance was most common to ampicillin (29.8%) and sulfamethoxazole (29.1%), followed by trimethoprim (14.8%), trimethoprim/sulfamethoxazole (14.1%) and nalidixic acid (5.4%). Resistance in E. coli to co-amoxiclav, mecillinam, cefadroxil, nitrofurantoin, fosfomycin, gentamicin and ciprofloxacin was <3%. However, co-amoxiclav resistance was apparent in Portugal (9.3%) as was resistance to the quinolones, nalidixic acid and ciprofloxacin, in Portugal (11.6% and 5.8%, respectively) and Spain (26.7% and 14.7%, respectively). Overall, Proteus mirabilis were less resistant to ampicillin (16.1%) and more resistant to trimethoprim (25.5%) than E. coli, whereas Klebsiella spp. were more resistant to ampicillin (83.5%) and fosfomycin (56.7%). 'Other Enterobacteriaceae' were more resistant to the broad spectrum beta-lactams (ampicillin 45.9%, co-amoxiclav 21.3% and cefadroxil 24.6%), nitrofurantoin (40.2%) and fosfomycin (15.6%). In Staphylococcus saprophyticus resistance development was rare. Overall, antimicrobial resistance was lowest in the Nordic countries and Austria and highest in Portugal and Spain.

Adolescent↗
PubMed2002

Antibiotic prescription practices, consumption and bacterial resistance in a cross section of Swedish intensive care units.

BACKGROUND: The purpose of this work was to study usage of antibiotics, its possible determinants, and patterns of bacterial resistance in Swedish intensive care units (ICUs). METHODS: Prospectively collected data on species and antibiotic resistance of clinical isolates and antibiotic consumption specific to each ICU in 1999 were analyzed together with answers to a questionnaire. Antibiotic usage was measured as defined daily doses per 1000 occupied bed days (DDD1000). RESULTS: Data were obtained for 38 ICUs providing services to a population of approximately 6 million. The median antibiotic consumption was 1257 DDD1000 (range 584-2415) and correlated with the length of stay but not with the illness severity score or the ICU category. Antibiotic consumption was higher in the ICUs lacking bedside devices for hand disinfection (2193 vs. 1214 DDD1000, p=0.05). In the ICUs with a specialist in infectious diseases responsible for antibiotic treatment the consumption pattern was different only for use of glycopeptides (58% lower usage than in other ICUs: 26 vs. 11 DDD1000,P=0.02). Only 21% of the ICUs had a written guideline on the use of antibiotics, 57% received information on antibiotic usage at least every 3 months and 22% received aggregated resistance data annually. Clinically significant antimicrobial resistance was found among Enterbacter spp. to cephalosporins and among Enterococcus spp. to ampicillin. CONCLUSIONS: Availability of hand disinfection equipment at each bed and a specialist in infectious diseases responsible for antibiotic treatment were factors that correlated with lower antibiotic consumption in Swedish ICUs, whereas patient-related factors were not associated with antibiotic usage.

Adult↗
PubMed2002

Clonal spread among Swedish children of a Staphylococcus aureus strain resistant to fusidic acid.

An increased incidence of fusidic acid-resistant Staphylococcus aureus strains causing superficial infections among children in Sweden has been noted since the mid-1990s. Based on routine susceptibility testing data from 10 laboratories representing 8/21 Swedish counties during 1990-2001, the increase was first demonstrated in southern Sweden and subsequently became apparent throughout the country. Epidemiological typing using pulsed-field gel electrophoresis of recent isolates of fusidic acid-resistant S. aureus from 11 laboratories representing 8/21 Swedish counties revealed a high degree of similarity of band patterns, indicating a clonal relationship. Data from 1 of the laboratories demonstrated a close connection between this clone and impetigo. Sales statistics showed a pronounced increase in the use of fusidic acid ointments in the 0-12 y age group from 1998 onwards. There was, however, no statistically significant correlation between sales of fusidic acid ointments and resistance among S. aureus strains to fusidic acid.

Administration, Topical↗
PubMed2001

Methods for identifying methicillin resistancein Staphylococcus aureus.

Five methods for the detection of methicillin-resistant Staphylococcus aureus were used to examine a collection of 100 clinical isolates comprising both susceptible and resistant strains. The disc diffusion test with oxacillin had a sensitivity of 93.3% and a specificity of 92.0% whereas mannitol salt agar containing oxacillin had a sensitivity of 100% and specificity 80.6% with high inoculum. With a low inoculum the sensitivity was 90.7% and specificity 96.0%. The MRSA screen test (Denka Seiken Co. Ltd., Japan) and Evigene MRSA Detection Kit (State Serum Institute, Denmark) tests were in complete agreement with results obtained with polymerase chain reaction assays amplifying mecA and nuc gene sequences.

Bacterial Proteins↗
PubMed2000

The ECO*SENS Project: a prospective, multinational, multicentre epidemiological survey of the prevalence and antimicrobial susceptibility of urinary tract pathogens-interim report.

The ECO*SENS Project is the first international survey to investigate the prevalence and susceptibility of pathogens causing community-acquired, uncomplicated urinary tract infections (UTIs) in women. At 240 centres in 17 countries, female patients presenting with symptoms of uncomplicated UTIs were asked to provide a urine sample for testing for the presence of leucocytes and bacteria. The bacteria were identified and their susceptibility to 12 antibiotics commonly used in the treatment of UTIs was determined. The objective of the survey was to collect 5000 urine samples to obtain approximately 3500 isolates of defined uropathogens. This interim report includes the results from 1960 urine samples, 75% of which contained a uropathogen. Escherichia coli accounted for the majority (80%) of uropathogens isolated in all 17 countries. The rates of resistance among E. coli strains were: ampicillin and sulphamethoxazole, 30%; trimethoprim alone or with sulphamethoxazole, 15%; nalidixic acid, 6%; ciprofloxacin, 3%; amoxycillin-clavulanic acid, mecillinam, cefadroxil, nitrofurantoin and fosfomycin, 2%. The use of ampicillin, sulphonamides and trimethoprim alone or with sulphamethoxazole needs to be reconsidered. The seemingly rapid increase in quinolone resistance among community-acquired E. coli in some of the countries gives cause for concern.

Journal Article↗