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Susceptibility Testing (susceptibility + testing)
Kinds of Susceptibility Testing Selected AbstractsAntifungal susceptibility testing by flow cytometry: is it the future?MYCOSES, Issue 4 2006Luís André Vale-Silva Summary The current increase in the number and significance of fungal infections, the expanding armamentarium of antifungal agents, and the emergence of the problem of antifungal drug resistance have been intensifying the importance of antifungal susceptibility testing (AST). The Clinical and Laboratory Standards Institute (CLSI, formerly NCCLS) in the United States and the Antifungal Susceptibility Testing Subcommittee of the European Committee on Antimicrobial Susceptibility Testing (AFST-EUCAST) published standard methodologies in order to achieve higher reproducibility and allow direct inter-laboratory comparison of the susceptibility results. Nevertheless, several problems remain unresolved and the methods depend on long incubation periods of a minimum of 24 h (EUCAST) or even 48 h (CLSI). Over the last 15 years, successful applications of flow cytometric techniques to AST of both yeast and moulds have been reported. These techniques are based on the analysis of a great number of fungal cells individually and frequently rely on short incubation times of no more than a few hours. Considering these attributes, flow cytometry (FC) seems to have the potential to achieve clinical usefulness in the near future. The collection of data on the reproducibility of the results and on the correlation with clinical outcomes has barely started, however. Practical validation of the experimental methodologies is not granted before a significant amount of data addressing those questions is available. [source] European Committee on Antimicrobial Susceptibility Testing (EUCAST) Technical Notes on antimicrobial susceptibility testingCLINICAL MICROBIOLOGY AND INFECTION, Issue 6 2006G. Kahlmeter Abstract 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. [source] Correlation between the procedure for antifungal susceptibility testing for Candida spp. of the European Committee on Antibiotic Susceptibility Testing (EUCAST) and four commercial techniquesCLINICAL MICROBIOLOGY AND INFECTION, Issue 6 2005M. Cuenca-Estrella Abstract The correlation between results obtained with the European Committee on Antibiotic Susceptibility Testing (EUCAST) antifungal susceptibility testing procedure (document 7.1) and four commercial systems was evaluated for a collection of 93 clinical isolates of Candida spp. Overall, agreement between the EUCAST procedure and the Sensititre YeastOne and Etest methods was 75% and 90.4%, respectively. The correlation indices (p < 0.01) between the EUCAST and commercial methods were 0.92 for Sensititre YeastOne, 0.89 for Etest, ,,0.90 for Neo-Sensitabs, and 0.95 for Fungitest. Amphotericin B MICs obtained by Sensititre YeastOne were consistently higher than with the EUCAST method and, although very major errors were not observed, 91% of MICs were misclassified. Amphotericin B- and fluconazole-resistant isolates were identified correctly with Sensititre YeastOne, Etest and Fungitest. Neo-Sensitabs identified amphotericin B-resistant isolates, but misclassified >,5% of fluconazole-resistant isolates as susceptible. The commercial methods, particularly Etest and Fungitest, appeared to be suitable alternatives to the EUCAST procedure for antifungal susceptibility testing of clinical isolates of Candida. [source] Multicenter evaluation of the reproducibility of the proposed antifungal susceptibility testing method for fermentative yeasts of the Antifungal Susceptibility Testing Subcommittee of the European Committee on Antimicrobial Susceptibility Testing (AFST-EUCAST)CLINICAL MICROBIOLOGY AND INFECTION, Issue 6 2003M. Cuenca-Estrella Objective To evaluate the intra- and inter-laboratory reproducibility of a new standard for susceptibility testing of fermentative yeasts. This standard is based on the M27-A procedure of the National Committee for Clinical Laboratory Standards (NCCLS), but incorporates several modifications, including spectrophotometric growth-dependent endpoint reading. Methods Nine laboratories participated in the study. Common material lots were used to test six Candida species (one each of C. albicans, C. tropicalis, C. parapsilosis, C. glabrata, C. krusei, and C. lusitaniae), and two quality control strains (C. krusei ATCC6258 and C. parapsilosis ATCC22019). Triplicate testing on three separate days was performed in microtiter format with RPMI,2% glucose, pH 7.0. Flucytosine, fluconazole and itraconazole were tested. In total, 3888 MIC values were included in the analyses. Reproducibility was calculated by means of agreement (percentage of MICs within one two-fold dilution of the mode) and intraclass correlation coefficient (ICC, maximum value of 1). Results The average intra-laboratory agreements were 99% and 96% after 24 h and 48 h of incubation, respectively, with ICCs of 0.98 and 0.97 (P < 0.05). Two strains exhibiting a trailing effect showed intra-laboratory agreement of 92% and ICCs of <,0.91 at 48 h. The inter-laboratory agreement was 94% and 88% after 24 h and 48 h, respectively, with ICCs of 0.93 and 0.91 (P < 0.05). Lower values of agreement and ICCs were obtained for strains exhibiting trailing after 48 h of incubation. Itraconazole yielded the lowest values of reproducibility. Conclusion The new procedure of EUCAST for antifungal susceptibility testing is a reproducible method within and between laboratories and offers several advantages over the NCCLS approved method. [source] The HOMER Study: The Effect of Increasing the Dose of Metronidazole When Given with Omeprazole and Amoxicillin to Cure Helicobacter pylori InfectionHELICOBACTER, Issue 4 2000Karna Dev Bardhan Background.Helicobacter pylori eradication with omeprazole, amoxycillin, and metronidazole is both effective and inexpensive. However, eradication rates with different dosages and dosing vary, and data on the impact of resistance are sparse. In this study, three different dosages of omeprazole, amoxycillin, and metronidazole were compared, and the influence of metronidazole resistance on eradication was assessed. Methods. Patients (n = 394) with a positive H. pylori screening test result and endoscopy-proven duodenal ulcer in the past were enrolled into a multicenter study performed in four European countries and Canada. After baseline endoscopy, patients were randomly assigned to treatment for 1 week with either omeprazole, 20 mg twice daily, plus amoxycillin, 1,000 mg twice daily, plus metronidazole, 400 mg twice daily (low M); or omeprazole, 40 mg once daily, plus amoxycillin, 500 mg three times daily, plus metronidazole, 400 mg three times daily (medium M); or omeprazole, 20 mg twice daily, plus amoxycillin, 1,000 mg twice daily, plus metronidazole, 800 mg twice daily (high M). H. pylori status at entry was assessed by a 13C urea breath test and a culture. Eradication was defined as two negative 13C-urea breath test results 4 and 8 weeks after therapy. Susceptibility testing using the agar dilution method was performed at entry and in patients with persistent infection after therapy. Results. The eradication rates, in terms of intention to treat (ITT) (population n = 379) (and 95% confidence interval [CI]) were as follows: low M 76% (68%, 84%), medium M 76% (68%, 84%), and high M 83% (75%, 89%). By per-protocol analysis (population n = 348), the corresponding eradication rates were: low M 81%, medium M 80%, and high M 85%. No H. pylori strains were found to be resistant to amoxycillin. Prestudy resistance of H. pylori strains to metronidazole was found in 72 of 348 (21%) of the cultures at entry (range, 10%,39% in the five countries). The overall eradication rate in prestudy metronidazole-susceptible strains was 232 of 266 (87%) and, for resistant strains, it was 41 of 70 (57%; p < .001). Within each group, the results were as follows (susceptible/resistant): low M, 85%/54%; medium M, 86%/50%; and high M, 90%/75%. There were no statistically significant differences among the treatment groups. 23 strains susceptible to metronidazole before treatment were recultured after therapy failed; 20 of these had now developed resistance. Conclusions.H. pylori eradication rates were similar (approximately 80%) with all three regimens. Metronidazole resistance reduced efficacy; increasing the dose of metronidazole appeared not to overcome the problem or significantly improve the outcome. Treatment failure was generally associated with either prestudy or acquired metronidazole resistance. These findings are of importance when attempting H. pylori eradication in communities with high levels of metronidazole resistance. [source] Helicobacter pylori antimicrobial resistance in the United Kingdom: the effect of age, sex and socio-economic statusALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 9 2001H. K. Parsons Background: Helicobacter pylori antimicrobial resistance is the most common reason for eradication failure. Small studies have shown metronidazole resistance to be more prevalent in certain population groups. Aim: To determine the resistance rates in a large cohort of patients from a single centre in the UK, and to evaluate resistance patterns over time, according to age, sex and socio-economic status. Methods: Consecutive patients with H. pylori -positive antral gastric biopsy samples were studied from 1994 to 1999. Susceptibility testing was performed to metronidazole, tetracycline, macrolide and amoxicillin by the modified disk diffusion method. The Jarman under-privileged area score was used as a measure of socio-economic status. Results: A total of 1064 patients were studied. Overall metronidazole resistance was 40.3%, decreasing with age (P < 0.0001, odds ratio for patients over 60 years 0.63, 95% CI: 0.48,0.80). Women were more likely to have metronidazole resistant strains (P=0.003, odds ratio 1.5, 95% CI: 1.15,1.91), but there was no association with Jarman score. Macrolide resistance was associated with metronidazole resistance (P=0.03, odds ratio 2.14, 95% CI: 1.07,4.28). Conclusions: Metronidazole resistance in H. pylori is highly prevalent and more common in women and the young, but does not appear to be related to socio-economic status. [source] High Level of Antimicrobial Resistance in French Helicobacter pylori IsolatesHELICOBACTER, Issue 1 2010Josette Raymond Abstract Background: Helicobacter pylori is a human pathogen responsible for serious diseases including peptic ulcer disease and gastric cancer. The recommended triple therapy included clarithromycin but increasing resistance has undermined its effectiveness. It is therefore important to be aware of the local prevalence of antimicrobial resistance to adjust treatment strategy. Materials and Methods: Overall, 530 biopsies were collected between 2004 and 2007. The antimicrobial susceptibility of H. pylori was determined by E-test and molecular methods. Results: Among these, 138/530 (26%) strains were resistant to clarithromycin, 324/530 (61%) to metronidazole and 70/530 (13.2%) to ciprofloxacin. Whereas no resistance against amoxicillin and tetracycline was observed, only one strain was resistant to rifampicin. Compared to the patients never treated for H. pylori infection, the prevalence of resistance was significantly higher in patients previously treated (19.1% vs 68% for clarithromycin; 13.2% vs 53.3% for both clarithromycin and metronidazole). The trend analysis revealed an increase of primary resistance to ciprofloxacin between 2004 and 2005 (7.3%) vs 2006,2007 (14.1%) (p = .04) and the secondary resistance reached 22.7% in 2007. Interestingly, 27 biopsies (19.6%) contained a double population of clarithromycin-susceptible and -resistant strains. Conclusions: The reported high prevalence of clarithromycin and multiple resistances of H. pylori suggest that the empiric therapy with clarithromycin should be abandoned as no longer pretreatment susceptibility testing has assessed the susceptibility of the strain. As culture and antibiogram are not routinely performable in most clinical laboratories, the use of molecular test should be developed to allow a wide availability of pretreatment susceptibility testing. [source] Resistant Pathogens in Urinary Tract InfectionsJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 2002Lindsay E. Nicolle MD Antimicrobial susceptibility of bacteria causing urinary tract infection (UTI) has evolved over several decades as antimicrobial exposure has repeatedly been followed by emergence of resistance. Older populations in the community, long-term care facilities, or acute care facilities have an increased prevalence of resistant bacteria isolated from UTI. Resistant isolates are more frequent in long-term care populations than the community. Resistant isolates include common uropathogens, such as Escherichia coli or Proteus mirabilis, and organisms with higher levels of intrinsic resistance, such as Pseudomonas aeruginosa or Providencia stuartii. Isolation of resistant organisms is consistently associated with prior antimicrobial exposure and higher functional impairment. The increased likelihood of resistant bacteria makes it essential that a urine specimen for culture and susceptibility testing be obtained before instituting antimicrobial therapy. Therapy for the individual patient must be balanced with the possibility that antimicrobial use will promote further resistance. Antimicrobial therapy should be avoided unless there is a clear clinical indication. In particular, asymptomatic bacteriuria should not be treated with antimicrobials. Where symptoms are mild or equivocal, urine culture results should be obtained before initiating therapy. This permits selection of specific therapy for the infecting organism and avoids empiric, usually broad-spectrum, therapy. Where empirical therapy is necessary, prior infecting organisms should be isolated, and recent antimicrobial therapy, as well as regional or facility susceptibility patterns, should be considered in antimicrobial choice. Where empirical therapy is used, it should be reassessed 48 to 72 hours after initiation, once pretherapy cultures are available. [source] Comparison of phenotypic and genotypic markers for characterization of an outbreak of Salmonella serotype Havana in captive raptorsJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2003M.P. Reche Abstract Aims: To establish a typing method for tracing the epidemic relationship of 16 strains of Salmonella serotype Havana isolated from captive raptors showing no symptomatology and residing in a wildlife hospital in Spain. Methods and Results: Antimicrobial susceptibility testing, ribotyping, pulsed field gel electrophoresis (PFGE) and amplified fragment length polymorphism (AFLP) methodology were applied. Ten unrelated strains of serotype Havana were included as a control group to provide a basis of for the efficiency of the different markers used. All outbreak-related strains were resistant to nalidixic acid and streptomycin and showed the same ripotype, pulsotype and AFLP pattern. Conclusions: This is the first time that AFLP analysis has been tested with serotype Havana isolates and it has demonstrated to be the most useful epidemiological tool for discriminating between unrelated and outbreak-related strains of this serotype. The results obtained suggest that all the Salmonella serotype Havana isolates represented a common outbreak strain whose origin of contamination could not be established although it is thought that it was the poultry meat used for raptors'diet. Significance and Impact of the Study: Our study suggests the importance of microbiological analysis of these products in order to prevent contamination and dissemination of Salmonellae in this kind of Hospital. [source] Novel method for clearing red blood cell debris from BacT/ALERT® blood culture medium for improved microscopic and antimycobacterial drug susceptibility test resultsJOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 4 2007Krishnamoorthy Gopinath Abstract Even though automation in mycobacterial culture has immensely improved the detection of organisms, identification of species and antimycobacterial susceptibility testing from blood culture bottles remain cumbersome and error-prone due to the presence of intact red blood cells (RBCs). The removal or lysis of these RBCs and excessive protein from the blood components could theoretically help improve this process. The present study reports an effective method that uses ammonium chloride (NH4Cl) and Triton X-100 to lyse the RBCs in blood culture medium. The method was optimized by preparing various concentrations of NH4Cl and Triton X-100, and incubation conditions, leading to eight protocols. The lysis protocol with a concentration of 150,mM of NH4Cl, 0.5% Triton X-100, and 1% potassium bicarbonate, pH 7.0, and incubation at 37°C for 15,min was found to be optimal. This method not only made the culture medium clear, the protein concentration decreased from 753.5±39.4 to 53.2±4.2,mg/mL in the M. tuberculosis -spiked culture medium and in the blood culture medium inoculated with the blood from tuberculosis patients. The method had no adverse effect on mycobacteria, and no depletion of M. tuberculosis colony-forming units was found. The lysate could be used for antimycobacterial susceptibility testing with no difficulty in setting the mycobacterial concentration of inoculum to 0.5 McFarland standards. Furthermore, this method had the added advantage in the microscopy and molecular methods for the speciation of Mycobacterium sp. J. Clin. Lab. Anal. 21:220,226, 2007. © 2007 Wiley-Liss, Inc. [source] Antimicrobial profiles of periodontal pathogens isolated from periodontitis patients in the Netherlands and SpainJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 8 2005A. J. Van Winkelhoff Abstract Background and Aim: Antimicrobial resistance of periodontal pathogens towards currently used antibiotics in periodontics has been investigated in a previous study. Microbial resistance in the periodontal microflora was more frequently observed in Spanish patients in comparison with Dutch patients. The aim of the present study was to compare antimicrobial susceptibility profiles of five periodontal bacteria isolated from periodontitis patients in Spain and in the Netherlands. Material and Methods: Subgingival plaque samples from adult patients with periodontitis were collected and cultured on selective and non-selective plates. Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum and Micromonas micros were isolated and used for minimal inhibitory concentration tests using the Epsilometer (E-test) technique. Eight different antibiotics were tested on all bacterial isolates. MIC50 and MIC90 values for each antibiotic and each species were determined and the percentage of resistant strains was calculated. Results: Significantly higher MIC values were noted in Spanish strains of F. nucleatum for penicillin, ciprofloxacin, of P. intermedia for penicillin, amoxicillin and tetracycline, of M. micros for tetracycline, amoxicillin and azithromycin, and of P. gingivalis for tetracycline and ciprofloxacin. Based on breakpoint concentrations, a higher number of resistant strains in Spain were found in F. nucleatum for penicillin, amoxicillin and metronidazole, in Prevotella intermedia for tetracycline and amoxicillin, and in A. actinomycetemcomitans for amoxicillin and azithromycin. Resistance of P. gingivalis strains was not observed for any of the antibiotics tested both in Spain and the Netherlands. Conclusions: Differences exist in the susceptibility profiles of periodontal pathogens isolated from periodontitis patients in Spain and in the Netherlands. This implicates that antibiotic susceptibility testing is necessary to determine efficacy of antimicrobial agents. Also, clinical studies with antibiotics should take these differences into account. The information from the present study indicates that it may not be possible to develop uniform protocols for usage of antibiotics in the treatment of severe periodontitis in the European Union. [source] A retrospective study of the clinical presentation of 140 dogs and 39 cats with bacteraemiaJOURNAL OF SMALL ANIMAL PRACTICE, Issue 8 2008M. Greiner Objectives: To evaluate retrospective data from 140 dogs and 39 cats with positive blood cultures that were presented to the Clinic for Small Animal Medicine in Munich from 1995 to 2004. Methods: The identity of bacteria isolated from blood cultures of dogs and cats with bacteraemia was determined, and clinical and laboratory findings and outcome of animals with Gram-negative versus Gram-positive bacteraemia were compared. Results: Sepsis was diagnosed in 81·7 per cent of dogs and 59·5 per cent of cats with bacteraemia. Escherichia coli was isolated in one third of the animals. Dogs with bacteraemia more often showed monocytosis and increased alkaline phosphatase activity, while in cats, hyperglycaemia was found more commonly. Dogs with Gram-negative bacteraemia had hypoalbuminaemia significantly more often than dogs with Gram-positive bacteraemia, while among the remaining parameters, there were no statistically significant differences. Clinical Significance: Not all dogs and cats with a positive blood culture met the criteria for sepsis. Bacteraemia caused by Gram-positive versus Gram-negative bacteria cannot be distinguished based on clinical or laboratory parameters, and bacterial culture and susceptibility testing have to be performed for the right choice of antibiotic treatment. [source] TRACING THE ORIGIN OF MULTI-DRUG RESISTANT (MDR) ESCHERICHIA COLI INFECTIONS FROM URINARY CATHETERS IN ICU CANINE PATIENTSJOURNAL OF VETERINARY EMERGENCY AND CRITICAL CARE, Issue S1 2004J Ogeer-Gyles Introduction: Urinary tract infections (UTIs) in dogs with urinary catheters in intensive care units (ICUs) are frequent. Historically, multi-drug resistant (MDR) Escherichia coli account for about 10% of the UTIs. The objectives of this study were to determine the frequency of E. coli infections and of MDR E. coli in dogs with UTIs in our ICU, and to assess whether the MDR E. coli were community-acquired or nosocomial in origin. Methods: Over a 1-year period, rectal swabs were taken from all dogs in the ICU on the day of admission (D0) and on days 3 (D3), 6 (D6), 9 (D9) and 12 (D12). Urine was collected on these days from dogs with an indwelling urinary catheter (n=190). Rectal swabs and urine were routinely cultured. E. coli isolates were identified by biochemical tests. Using NCCLS guidelines, antibiotic susceptibility testing was done by disk diffusion method on fecal and urinary E. coli isolates. Twelve antimicrobial agents were used: nalidixic acid, enrofloxacin, cephalothin, cefoxitin, cefotaxime, ceftiofur, trimethoprim-sulfa, chloramphenicol, gentamicin, tetracycline, ampicillin, and amoxicillin/clavulanate. Pulsed-field gel electrophoresis (PFGE) was used to compare MDR E. coli UTI strains with fecal E. coli strains from the same patient and with MDR fecal E. coli from patients that were adjacent to, or housed in the same cages. Results: E. coli was cultured from 12 (48%) of 25 UTIs. Two of the E. coli were MDR. For one dog, PFGE showed no similarities among fecal E. coli and the urinary MDR E. coli isolates from the patient or between these isolates and fecal E. coli from a dog housed in the same kennel on the previous day. The MDR E. coli UTI was likely acquired prior to admission to the ICU, as it was present on D0. For the other dog, PFGE showed genetic similarity but not complete identity between the D3 MDR E. coli urinary isolate and the D3, D6, D9 fecal MDR isolates. This suggests that the UTI originated with the fecal E. coli. Using selective plates, fecal MDR E. coli were not found on D0. Selection of the MDR strain in the intestine by the use of antibiotics occurred while the dog was in the ICU and possibly led to the UTI. Conclusions: Multi-drug resistant E. coli accounted for 2 of 12 E. coli UTIs in dogs in the ICU over a 1-year period. Genotyping showed that one of the two MDR E. coli infections could possibly be of nosocomial origin. [source] Antimicrobial Use in the Treatment of Calf DiarrheaJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 1 2004Peter D. Constable Calves with diarrhea often have small intestinal overgrowth with Escherichia coli bacteria, regardless of the inciting cause for the diarrhea, and 30% of systemically ill calves with diarrhea have bacteremia, predominantly because of E coli. Antimicrobial treatment of diarrheic calves should therefore be focused against E coli in the small intestine and blood, the 2 sites of infection. Fecal bacterial culture and antimicrobial susceptibility testing is not recommended in calves with diarrhea because fecal bacterial populations do not accurately reflect small intestinal or blood bacterial populations and because the break points for susceptibility test results have not been validated. Antimicrobial efficacy is therefore best evaluated by the clinical response of a number of calves to treatment, with calves randomly assigned to treatment groups. Amoxicillin, chlortetracycline, neomycin, oxytetracycline, streptomycin, sulfachloropyridazine, sulfamethazine, and tetracycline administered PO are currently labeled in the United States for the treatment of calf diarrhea. On the basis of published evidence for the oral administration of these antimicrobial agents, only amoxicillin can be recommended for the treatment of diarrhea. Dosage recommendations are amoxicillin trihydrate (10 mg/kg PO q12h) or amoxicillin trihydrate-clavulanate potassium (12.5 mg combined drug/kg PO q12h) for at least 3 days; the latter constitutes extra-label drug use. Parenteral administration of broad-spectrum ,-lactam antimicrobials,eftiofur (2.2mg/kg IM orSCq12h) and amoxicillin or ampicillin (10 mg/kg IM q12h),rpotentiatedsulfonamides(25 mg/kg IV or IM q24h) is recommended for treating calves with diarrhea and systemic illness; both constitute extra-label drug use. In calves with diarrhea and no systemic illness (normal appetite for milk, no fever), it is recommended that the health of the calf be monitored and that oral or parenteral antimicrobials not be administered. [source] Molecular characterization of early colonizer bacteria from wastes in a steel plantLETTERS IN APPLIED MICROBIOLOGY, Issue 4 2008D.B. Freitas Abstract Aims:, Forty-nine bacteria isolated from four newly-produced waste samples of a steel industry, which had a high content of CaO, MgO, Cr and P2O5, were characterized molecularly and phenotypically by susceptibility testing against heavy metals. Methods and Results:, Phylogenetic analysis using 16S rRNA gene sequences revealed that the isolates belonged to nine genera, Pseudomonas, Micrococcus, Acinetobacter, Bacillus, Dietzia, Kocuria, Diaphorobacter, Staphylococcus and Brevibacillus. Besides, some isolates could be affiliated to species: M. luteus, Ac. junii, Ac. schindleri, B. cereus, K. marina, D. nitroreducens and Staph. warneri. The bacteria that were characterized are taxonomically diverse, and Pseudomonas and Micrococcus predominated. Fingerprinting BOX-PCR revealed high genomic heterogeneity among the isolates. Among the heavy metal compounds Zn, Ni, Pb and Cu were least toxic to the bacterial isolates, whereas Ag inhibited all isolates at 0·001 mmol l,1. Conclusions:, Heterotrophic bacteria, affiliated with several phylogentic groups, were able to colonize different wastes of a steel industry. Significance and Impact of the Study:, This study extends our knowledge of the early colonizers bacteria populating siderurgic environments. Some of these bacteria could have potential for recycling siderurgic waste for steel production. [source] Molecular identification and characterization of rifampicin-resistant Mycobacterium tuberculosis isolates by line probe assay: an approach for rapid diagnosis of multidrug-resistant tuberculosisLETTERS IN APPLIED MICROBIOLOGY, Issue 3 2008C. Bicmen Abstract Aim:, Early identification and characterization of rifampicin-resistant (Rr) Mycobacterium tuberculosis isolates recovered from the samples of tuberculosis (TB) patients in the Aegean (West Anatolian) Region was intended. Methods and Results:, Sixty isolates [47 (78·3%) multidrug-resistant (MDR)], which were identified as M. tuberculosis complex and phenotypically resistant to rifampicin by both BACTEC mycobacteria growth indicator tube (MGIT) 960 and 460 systems were analysed by a commercial line probe assay (INNO-LiPA Rif TB). The concordance of LiPA with the in vitro susceptibility test was found as 98·3%. Among the isolates, S531L (R5 pattern; 46·7%) and L511P/R, S512T, Q513L/K (,S1 pattern; 11·7%) were the most frequent mutation patterns. As compared with the BACTEC systems and conventional techniques for cultivation, identification and in vitro susceptibility testing, INNO-LiPA Rif TB after cultivation in BACTEC MGIT 960 system provided an average of 20 days early diagnosis of RrM. tuberculosis isolates. Conclusions:, Rapid molecular identification and characterization of RrM. tuberculosis isolates after BACTEC MGIT 960 cultivation would be useful for faster diagnosis, infection control and planning of accurate treatment in MDR-TB patients. Significance and Impact of the Study:, Patients with MDR-TB need a specified treatment and efficient follow-up strategies. Rapid and practical methodologies to diagnose and follow these patients should be applied in routine use. [source] Ceragenin CSA-13 exhibits antimicrobial activity against cariogenic and periodontopathic bacteriaMOLECULAR ORAL MICROBIOLOGY, Issue 2 2009E. Isogai Introduction:, Ceragenin CSA-13 is a bile-acid-based mimic of endogenous antimicrobial peptides and shares a mechanism of action with many of these antimicrobial agents. Because CSA-13 is not peptide based, it is not a substrate for the proteases that are found in the oral cavity, which are capable of degrading antimicrobial peptides. Furthermore, the simplicity of the ceragenins makes them easier to prepare and purify than antimicrobial peptides. In this study, we examined the antimicrobial activities of CSA-13 against oral pathogens and found that this compound was bactericidal against all of the strains tested. Methods:, The strains used were isolates of Streptococcus mutans and Porphyromonas species. Minimum inhibitory concentrations (MIC) were determined using agar dilution methods. In susceptibility testing, viable counts were determined after incubation with CSA-13. Results:, CSA-13 was potent against all 23 strains tested with MICs of 1,8 ,g/ml for S. mutans and 1,16 ,g/ml for 24 strains of the genus Porphyromonas. The MIC50 was 2 and the MIC90 was 8 ,g/ml for S. mutans. MIC ranges for protease-positive P. gingivalis and P. cangingivaliswere 2,16 ,g/ml, and 1,2 ,g/ml for protease-negative P. circumdentaria. CSA-13 interacted with lipopolysaccharide-sensitized erythrocytes at a concentration of 5.0,20.0 ,g/ml. Conclusion:, CSA-13 displays broad-spectrum activity against cariogenic and periodontopathic bacteria. CSA-13 was effective against protease-positive Porphyromonas. It was shown to bind to erythrocytes coated with lipopolysaccharide and lipoteichoic acid from diverse bacterial strains. These results suggest that CSA-13 may be useful for the prevention and treatment of oral microbial diseases. [source] In vitro susceptibility testing in fungi: a global perspective on a variety of methodsMYCOSES, Issue 1 2010Cornelia Lass-Flörl Summary Candida and Aspergillus species are the most common causes of invasive fungal infections in immunocompromised patients. The introduction of new antifungal agents and recent reports of resistance emerging during treatment have highlighted the need for in vitro susceptibility testing. For some drugs, there is a supporting in vitro,in vivo correlation available from studies of clinical efficacy. Both intrinsic and emergent antifungal drug resistance are encountered. Various testing procedures have been proposed, including macrodilution and microdilution, agar diffusion, disk diffusion and Etest. Early recognition of infections caused by pathogens that are resistant to one or more antifungals is highly warranted to optimise treatment and patient outcome. [source] Direct fluconazole susceptibility testing of positive Candida blood cultures by flow cytometryMYCOSES, Issue 3 2008Bernard Rudensky Summary The standard methods for yeast susceptibility testing require 24,48 h of incubation. As there has been an increase in incidence of non- albicans Candida species, the clinician is very often wary of initiating therapy with fluconazole until a final susceptibility report is generated, especially when treating very sick patients. A rapid reliable susceptibility testing method would enable the clinician to prescribe fluconazole, thus avoiding more toxic or expensive therapy. To determine the feasibility of direct susceptibility testing of Candida species to fluconazole by a rapid flow cytometric method, 50 Candida strains were seeded into blood culture bottles and were tested for susceptibility to fluconazole directly from the bottles after their being flagged as positive by the blood culture instrument. Minimal inhibitory concentration (MIC) determined by fluorescent flow cytometry (FACS) showed excellent agreement to that determined by macrodilution. Following the seeding experiments, 30 true patient specimens were tested directly from positive blood cultures, and MIC determined by both methods showed excellent agreement. Antifungal susceptibility testing by FACS directly from positive blood culture bottles is a reliable, rapid method for susceptibility testing of Candida to fluconazole. The method allows same-day results, does not require subculture to agar media, and can greatly assist in the selection of appropriate antifungal therapy. [source] Antifungal susceptibility testing by flow cytometry: is it the future?MYCOSES, Issue 4 2006Luís André Vale-Silva Summary The current increase in the number and significance of fungal infections, the expanding armamentarium of antifungal agents, and the emergence of the problem of antifungal drug resistance have been intensifying the importance of antifungal susceptibility testing (AST). The Clinical and Laboratory Standards Institute (CLSI, formerly NCCLS) in the United States and the Antifungal Susceptibility Testing Subcommittee of the European Committee on Antimicrobial Susceptibility Testing (AFST-EUCAST) published standard methodologies in order to achieve higher reproducibility and allow direct inter-laboratory comparison of the susceptibility results. Nevertheless, several problems remain unresolved and the methods depend on long incubation periods of a minimum of 24 h (EUCAST) or even 48 h (CLSI). Over the last 15 years, successful applications of flow cytometric techniques to AST of both yeast and moulds have been reported. These techniques are based on the analysis of a great number of fungal cells individually and frequently rely on short incubation times of no more than a few hours. Considering these attributes, flow cytometry (FC) seems to have the potential to achieve clinical usefulness in the near future. The collection of data on the reproducibility of the results and on the correlation with clinical outcomes has barely started, however. Practical validation of the experimental methodologies is not granted before a significant amount of data addressing those questions is available. [source] The colonization incidence of group B streptococcus in pregnant women and their newborns in IstanbulPEDIATRICS INTERNATIONAL, Issue 1 2005Ilikkan Barbaros Abstracts,Background:,This study was designed to determine the incidence of group B Streptococcus (GBS) colonization in pregnant women and newborns, and to evaluate the antimicrobial resistance during delivery. Methods:,A total of 300 pregnant women and their newborns were enrolled in this prospective study performed in the maternity ward of Cerrahpasa Medical Faculty and Bakirkoy SSK Hospital, Istanbul, Turkey. Samples were collected from pregnant women and their newborns in the delivery room. Results:,GBS was isolated from 24 women and the colonization rate was found to be 8%. Two newborns were colonized with GBS. None of the isolates were resistant to penicillin, whereas 20% showed resistance to erythromycin and clindamycin. Conclusion:,Screening and antimicrobial susceptibility testing of GBS during pregnancy show similiar results with other studies performed in different regions of our country. [source] Drug-resistant tuberculosis: Past, present, futureRESPIROLOGY, Issue 3 2010Chen-Yuan CHIANG ABSTRACT In a population of Mycobacterium tuberculosis, random chromosomal mutation that results in genetic resistance to anti-tuberculosis (TB) drugs occurs at a relatively low frequency. Anti-TB drugs impose selection pressure so that mycobacterial mutants gradually outnumber susceptible bacilli and emerge as the dominant strains. Resistance to two or more anti-TB drugs represents cumulative results of sequential mutation. The fourth report on global anti-TB drug resistance provides the latest data on the extent of such problem in the world. The median prevalence of multi-drug-resistant TB (MDR-TB) in new TB cases was 1.6%, and in previously treated TB cases 11.7%. Of the half a million MDR-TB cases estimated to have emerged in 2006, 50% were in China and India. The optimal duration of any given combination of anti-TB drugs for treatment of MDR- and extensively drug-resistant TB (XDR-TB) has not been defined in controlled clinical trials. Standardized treatment may be feasible for MDR-TB patients not previously treated with second-line drugs, but a different strategy needs to be applied in the treatment of MDR-TB patients who have received second-line drugs before. Unfortunately, the reliability of drug susceptibility testing of most second-line anti-TB drugs is still questionable. Drug-resistant TB is not necessarily less virulent. Findings from modelling exercise warned that if MDR-TB case detection and treatment rates increase to the World Health Organization target of 70%, without simultaneously increasing MDR-TB cure rates, XDR-TB prevalence could increase exponentially. Prevention of development of drug resistance must be accorded the top priority in the era of MDR-/XDR-TB. [source] Sample survey of drug-resistant tuberculosis in Henan, China, 1996RESPIROLOGY, Issue 1 2002GUOBIN WANG Background: There is little reliable data on the global drug resistance to tuberculosis (TB) as most of the existing data is based upon biased samples, is not standardized or was obtained using poor techniques. For this reason, the World Health Organization (WHO) and the International Union Against Tuberculosis and Lung Disease (IUATLD) developed a global project on anti-TB drug resistance surveillance (DRS) in 1994. China joined this project in 1995 and the province of Henan was selected as the first site for collection of representative samples to survey the prevalence of drug-resistant TB. Methodology: Standard drug susceptibility testing by the proportion method against streptomycin (S), isoniazid (H), rifampicin (R), and ethambutol (E) was performed with Mycobacterium tuberculosis isolated from 916 new cases and 456 previously treated cases. Treatment outcome of these patients has been evaluated according to the regimens and drug susceptibility patterns. Results: Drug resistance among new cases to any drug was found to be 43.0% and any resistance: S, 32.5%; H, 31.0%; R, 20.7%; and E, 10.3%. Drug resistance among previously treated cases to any drug was 68.2% and any resistance: S, 52.2%; H, 49.3%; R, 48.3%; and E, 20.4%. The cure rate for new cases was 43.3% and 29.4% for previously treated cases. The poor cure rate resulted mainly from a high defaulter rate. Conclusion: Drug-resistant TB was found to be highly prevalent in Henan and the cure rate remained poor. The results strongly indicated that Henan should take immediate action to improve the cure rate of patients through expansion of the introduction of the directly observed treatment short-course strategy. [source] Outbreak of CTX-M-15-producing Klebsiella pneumoniae of sequence type 199 in a Latvian teaching hospitalAPMIS, Issue 9 2010UGA DUMPIS Dumpis U, Iversen A, Balode A, Saule M, Mikla,evi,s E, Giske CG. Outbreak of CTX-M-15-producing Klebsiella pneumoniae of sequence type 199 in a Latvian teaching hospital. APMIS 2010; 118: 713,6. Previous studies on the epidemiology of extended-spectrum ,-lactamase (ESBL)-producing Enterobacteriaceae in Latvia are lacking. ESBL-producing Klebsiella pneumoniae (n = 32) were subjected to pulsed-field gel electrophoresis (PFGE) and selected isolates to multi-locus sequence typing (MLST). Species identification and susceptibility testing were performed using VITEK2, and sequencing of blaCTX-M was performed in selected isolates. PFGE revealed one major clone (n = 23), with most of the isolates derived from the ICU. The clone harboured blaCTX-M-15, was sequence type 199 and comprised two ertapenem non-susceptible isolates. This is the first report of an ESBL outbreak in Latvia, and calls for increased epidemiological typing of ESBL-producing Enterobacteriaceae, as well as improved infection control routines. [source] Vancomycin-resistant Enterococcus spp.: validation of susceptibility testing and in vitro activity of vancomycin, linezolid, tigecycline and daptomycinAPMIS, Issue 1 2010MATHIAS RATHE Rathe M, Kristensen L, Ellermann-Eriksen S, Thomsen MK, Schumacher H. Vancomycin-resistant Enterococcus spp.: validation of susceptibility testing and in vitro activity of vancomycin, linezolid, tigecycline and daptomycin. APMIS 2010; 118: 66,73. Vancomycin-resistant enterococci (VRE) have emerged to become a significant nosocomial pathogen. However, detection may be challenging and treatment possibilities are limited. Reports of resistance to linezolide, daptomycin and tigecycline underline the need for reliable susceptibility testing with respect to these compounds. We evaluated the in vitro activity of vancomycin, linezolid, daptomycin and tigecycline against a panel of VRE and vancomycin-susceptible enterococci by broth microdilution (BMD). Etest for determination of minimum inhibitory concentration of these four antibiotics and two disc diffusion assays for detecting VRE and for susceptibility testing against tigecycline and linezolid were evaluated. Before susceptibility testing, all isolates were classified by polymerase chain reaction as vanA or vanB gene positive or vanA/B gene negative. Linezolid, daptomycin and tigecycline had excellent in vitro activity towards all isolates. For daptomycin and tigecycline, the overall agreement between BMD and Etest was suboptimal. For both disc diffusion assays, use of current break points was inadequate to detect vancomycin resistance for isolates carrying the vanB gene. Inspection of the inhibition zone for a diffuse edge, as recommended, accurately predicted presence of the vanB gene. [source] Evaluation of the VITEK 2 cards for identification and antimicrobial susceptibility testing of non-glucose-fermenting Gram-negative bacilliAPMIS, Issue 4 2009WEN-SHYANG HSIEH We evaluated VITEK 2 cards (NGNC and AST-GN10) for the accuracy of identification (ID) and antimicrobial susceptibility testing (AST) of non-glucose-fermenting Gram-negative bacilli (NGF-GNB). In a total of 201 strains, 190 strains (94.5%) were correctly identified, seven strains (3.5%) showed low discrimination, four strains (2.0%) had discrepancies, and no strain remained unidentified. Reference AST of amikacin, aztreonam, cefepime, cefotaxime, ceftazidime, ciprofloxacin, imipenem, levofloxacin, piperacillin-tazobactam, and trimethoprim-sulfamethoxazole was performed by the agar dilution method. Approximately 82.5% of ID and 72.9% of AST were completed within 7 and 14 h, respectively. For NGF-GNB, other than Pseudomonas aeruginosa, Acinetobacter spp., Stenotrophomonas maltophilia, and the Burkholderia cepacia group, essential agreements (EAs) were 93.6,100.0%. Severe disagreements (resistant by the reference method to susceptible by AST-GN10) were observed for amikacin (0.9%), cefepime (1.8%), cefotaxime (1.8%), imipenem (0.9%), and piperacillin-tazobactam (0.9%). One major disagreement (susceptible to resistant) was observed for ceftazidime (0.1%). For P. aeruginosa, EAs were 85.7,100%, with severe disagreements observed for cefepime (4.8%) and piperacillin-tazobactam (4.8%). For Acinetobacter spp., EAs were 86.4,100% without disagreements. The VITEK 2 cards appear to be promising for rapid ID and reliable AST for most species of NGF-GNB. [source] Application of molecular genetic methods in macrolide, lincosamide and streptogramin resistance diagnostics and in detection of drug-resistant Mycobacterium tuberculosis,APMIS, Issue 11-12 2004JARI JALAVA Antimicrobial susceptibility testing has traditionally been based on measurements of minimal inhibitory concentrations of antimicrobials. Molecular genetic studies on antimicrobial resistance have produced a great deal of genetic information which can be used for diagnosis of antimicrobial resistance determinants. Bacteria can acquire resistance to macrolides, lincosamides and streptogramin antibiotics by modification of the target site of the drugs, by active efflux of the drugs, and by inactivation of the drugs. The genetic backgrounds of these resistance mechanisms are well known and several molecular methods for detection of resistance determinants have been developed. Outbreaks of multidrug-resistant tuberculosis have focused international attention on the emergence of Mycobacterium tuberculosis strains that are resistant to antimycobacterial agents. Knowledge of the antimycobacterial resistance genetics and progress in molecular methods has made it possible to develop rapid molecular methods for susceptibility testing. This review presents the genetic background of drug resistance and introduces some methods for genotypic susceptibility testing. [source] Calibration of fusidic acid disk diffusion susceptibility testing of Staphylococcus aureusAPMIS, Issue 10 2002BARBRO OLSSON-LILJEQUIST Single strain regression analysis, SRA, was used to calibrate disk diffusion fusidic acid susceptibility testing of Staphylococcus aureus in two laboratories using different standard methods but the same interpretative MIC limits. SRA equation constants were calculated using five different fusidic acid disk contents (1.5, 5, 15, 50, 150 ,g). These disks were tested on five separate occasions against quality control strain S. aureus ATCC 29213. The National Committee for Clinical Laboratory Standards (NCCLS) method was employed in Tartu, Estonia (TE) and the Swedish Reference Group for Antibiotics (SRGA) method in Sweden at the Karolinska Hospital (KS). SRA constants obtained were used for calculating zone breakpoints corresponding to MIC breakpoints recommended by the SRGA (S ,0.5 mg/L, R ,1 mg/L). Zone diameter histograms from KS, performed with a 50 ,g disk, and from TE, using a 10 ,g disk, showed a clustering of wild type strains around 41 mm and 30 mm, respectively, reflecting differences in methodology. Zone breakpoints calculated from the equations were validated by comparison with the histograms. Breakpoints were also calculated for a suggested lower disk content in Sweden, 10 ,g, and validated in tests of clinical isolates and by histogram analysis. [source] Efficacy of amoxycillin,clavulanate in an experimental model of murine pneumonia caused by AmpC-non-hyperproducing clinical isolates of Escherichia coli resistant to cefoxitinCLINICAL MICROBIOLOGY AND INFECTION, Issue 6 2008F. Docobo-Pérez Abstract The algorithms included in most automated systems used for antimicrobial susceptibility testing (e.g., Vitek 2) consider that Escherichia coli isolates resistant to cefoxitin are AmpC-hyperproducers and, consequently, resistant also to amoxycillin,clavulanate. However, a recent study revealed that 30% of E. coli clinical isolates resistant to cefoxitin remained susceptible in vitro to amoxycillin,clavulanate. The aim of the present study was to evaluate the in-vivo efficacy of amoxycillin,clavulanate in the treatment of an experimental model of pneumonia, using two clonally related isolates (with identical repetitive extragenic palindromic sequence (REP)-PCR patterns) of AmpC-non-hyperproducing and OmpF-lacking E. coli (Ec985 and Ec571) that were resistant to cefoxitin and susceptible to cefotaxime and amoxycillin,clavulanate. MICs were determined using a microdilution technique, and in-vitro bactericidal activity was tested using time-kill assays. The in-vivo efficacy of amoxycillin, amoxycillin,clavulanate and cefotaxime against both isolates was tested in a murine pneumonia model using immunocompetent C57BL/6 mice. Ec571 (a TEM-1/2 producer) was resistant to amoxycillin, whereas Ec985 (a TEM-1/2 non-producer) was susceptible. Amoxycillin, amoxycillin,clavulanate and cefotaxime were bactericidal for Ec985, and amoxycillin,clavulanate and cefotaxime were bactericidal for Ec571 at different concentrations and time-points, as determined using time-kill assays. Treatment with amoxycillin, amoxycillin,clavulanate and cefotaxime reduced the bacterial lung concentration of Ec985 compared with non-treated controls (p <0.05), whereas amoxycillin,clavulanate and cefotaxime showed efficacy against Ec571 when compared with the control and amoxycillin groups (p <0.05). Regardless of the exact underlying mechanism(s) of resistance, amoxycillin,clavulanate was effective in the experimental murine model in the treatment of pneumonia caused by AmpC-non-hyperproducing strains of E. coli resistant to cefoxitin. [source] European Committee on Antimicrobial Susceptibility Testing (EUCAST) Technical Notes on antimicrobial susceptibility testingCLINICAL MICROBIOLOGY AND INFECTION, Issue 6 2006G. Kahlmeter Abstract 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. [source] | |||||||||||||||||||||||||