this direct assay quality control detect all of these errors. In addition, if the wrong antibiotic is put in a prelabelled plate, the error may be detected if the observed zone size and/or zone edge differ from those that were expected. The spore suspension is particularly convenient, and it had been hoped that it could be used for the assay of all antibiotics except colistin. However, all thre...

AIMS To investigate the evolution of chromosomal and plasmid mediated resistance for ampicillin and tetracycline of N gonorrhoeae strains in Stockholm during 1982-1993. METHODS A total of 404 gonococcal strains isolated in 1982, 1987, 1990, 1992, 1993 were analysed for minimal inhibitory concentrations (MIC) of ampicillin and tetracycline and for plasmid content. MIC values were determined by...

The increasing prevalence of penicillin-resistant Streptococuus pneumoniae urges for fast and accurate susceptibility testing methods. This study evaluated the comparability of three commonly used techniques; disk diffusion, E-test and agar dilution, to detect penicillin susceptibility in clinical isolates of S. pneumoniae. Fifty pneumococcal isolates, obtained from patients at the University o...

Neisseria meningitidis is one of the important cause of meningitis and has been extremely susceptible to penicillin. Nevertheless, moderately penicillin resistant strains have been reported in some parts of the world. To our knowledge, there is no such report in Malaysia. We report two clinical isolates that were found to have MICs of decreased susceptibility to penicillin by the agar dilution ...

Recent studies have questioned treatment of serious methicillinresistant Staphylococcus aureus (MRSA) infections with vancomycin because of treatment failures, despite vancomycin MICs in the susceptible category (MIC 2 g/ml) (2, 3, 5, 6, 7). Some of these studies have used broth microdilution for determining vancomycin MICs (5), while others have used the Etest commercial product (AB Biodisk, S...

A parametric method of statistical analysis for dilution assays is developed in detail from first principles of probability and statistics. The method is based on a simple product binomial model for the experiment and produces an estimate for the concentration of target entities, a confidence interval for this concentration, and an indicator of the quality of the assay called the p value for go...

OBJECTIVES In vitro susceptibility testing of 31 Bartonella spp. strains including 21 Bartonella henselae isolates was performed for 17 antimicrobial agents (telithromycin, four macrolides, five fluoroquinolones, five aminoglycosides, doxycycline and rifampicin). METHODS MICs were determined by agar dilution and Etest using chocolate agar containing 5% defibrinated sheep blood as assay medium...

MICs of amikacin, cefoxitin, ciprofloxacin, clarithromycin, doxycycline, and imipenem were determined by Etest for 100 clinical strains of rapidly growing mycobacteria and compared with MICs determined by a reference agar dilution method. Etest MICs were also determined by an alternative inoculum application (agar overlay) method and compared with MICs determined by the inoculum application met...

In vitro activities of 17 antibiotics against 53 clinical strains of Mycobacterium marinum, an atypical mycobacterium responsible for cutaneous infections, were determined using the reference agar dilution method. Rifampin and rifabutin were the most active drugs (MICs at which 90% of the isolates tested were inhibited [MIC(90)s], 0.5 and 0.6 microgram/ml, respectively). MICs of minocycline (MI...