When there is resistance to any firstline drug, secondline drug susceptibility testing is performed. The correlation between clinical outcome and drug susceptibility testing breakpoints other than for the macrolides is regarded to be poor. This report includes results for a subset of laboratories performing drug susceptibility tests dst for mtbc in the united states. Dec 01, 2009 the goals of testing are to detect possible drug resistance in common pathogens and to assure susceptibility to drugs of choice for particular infections. Verification of antimicrobial susceptibility testing.
Errors in interpretation and reporting results 28 7. Kirbybauer disk diffusion susceptibility test protocol asm. Before the advent of drug sensitivity testing, cancer clinicians made therapeutic decisions on an empirical basis in terms of the pathological features of the cancer, rather than by thorough understanding and evaluation of individual tumor and human responses to anticancer drugs in clinics. The demand for reliable drugsusceptibility testing dst increases with the expansion of antituberculosis drugresistance surveillance, and with the need for an appropriate treatment of multidrugresistant tuberculosis, whose incidence gradually increases in many parts of the world. Drug susceptibility testing laboratory information tb cdc. Apley, susceptibility testing, virginia vma, 2232018, page 5 microwell dilution testing example. Antimicrobial susceptibility testing protocols 1st. Antimycobacterial activity of drugs when incorporated. In this document, we attempt to answer many of the frequently asked questions regarding antimicrobial susceptibility testing. Susceptibility testing of fastidious bacteria 21 6. Microbiology data for systemic antibacterial drugs. Testing for these drugs is done using the kirby bauer method at this time, since they are not yet available for testing using the broth microdilution method. The mgit 960 platform has been extensively validated for testing susceptibility to firstline antitb agents at critical drug concentrations 2, 24.
Performance standards for antimicrobial susceptibility testing. In june 2010, the clinical and laboratory standards institute clsi published new mic and disk diffusion interpretive criteria i. Application of computers in antimicrobial susceptibility testing 39 10. Even though treatment regimen is started as soon as the diagnosis is made, continuing with testing is critical, as it can. In 2004, routine use of culture and drugsusceptibility testing dst was implemented for persons in 5 thailand provinces with a diagnosis of tuberculosis tb. A certain proportion of drug resistant bacteria exists in all populations of drug susceptible mtb. The role of drug susceptibility testing dst in the choice of agents for antimicrobial treatment of ntm disease, mainly that by slow growers, remains subject of debate. Drug susceptibility testing is a difficult procedure to standardize, and proficiency in performing these tests requires an understanding of many elements, including the. Intended use the bactec mgit 960 sire kit is used as a rapid qualitative procedure for susceptibility testing of mycobacterium tuberculosis, from culture, to streptomycin str, isoniazid inh, rifampin rif, and ethambutol emb. Feb 19, 2014 in 2004, routine use of culture and drug susceptibility testing dst was implemented for persons in 5 thailand provinces with a diagnosis of tuberculosis tb. Drtb drug resistant tuberculosis dst drug susceptibility testing ecoff epidemiological cutoff value fq fluoroquinolone e.
Who technical manual for drug susceptibility testing of. It is welldocumented that tb drug susceptibility testing dst is one of the most difficult procedures to standardize in the mycobacteriology laboratory 5. The process of verifying an antimicrobial susceptibility testing ast system can be very confusing. Editorial the new england journal of medicine 1474 n engl j med 379. The authors provide a comprehensive, uptodate procedural manual including protocols for. The demand for reliable drug susceptibility testing dst increases with the expansion of antituberculosis drug resistance surveillance, and with the need for an appropriate treatment of multidrugresistant tuberculosis, whose incidence gradually increases in many parts of the world. Effective evaluations of antimicrobial susceptibility tests asts require a robust study design. Rapid antimicrobial susceptibility test for identification. Drug susceptibility testing of mycobacterium tuberculosis in the diagnostic laboratory classi. What you need to know about testing sputum samples. In addition, there are several different reasons why verification might be necessary. Technical manual for drug susceptibility testing of.
Conventional methods for antimicrobial susceptibility. The most widely used testing methods include broth microdilution or rapid automated instrument methods that use commercially marketed materials and devices. Dst drug susceptibility testing ecoff epidemiological cutoff value fq fluoroquinolone e. Policy guidance on drugsusceptibility testing dst of. There is limited capability for testing drug combina. Fdacleared susceptibility test interpretive criteria for delafloxacin mic mcgml pathogen susceptible intermediate resistant staphylococcus aureus methicillinresistant and methicillin susceptible isolates. The coming of age of drugsusceptibility testing for. Potency and stability of drugs during laboratory manipulation. Here we systematically evaluated the performance of the mgit 960 instrumentation for quantitative susceptibility testing of drug resistant clinical isolates of m.
Quality control in antimicrobial susceptibility testing 29 8. Ernesto montoro, dihadenys lemus, miguel echemendia, anandi martin, francoise portaels, juan carlos palomino, comparative evaluation of the nitrate reduction assay, the mtt test, and the resazurin microtitre assay for drug susceptibility testing of clinical isolates of mycobacterium tuberculosis, journal of antimicrobial chemotherapy, volume 55, issue 4, april 2005, pages 500505, s. This takes a long time, first to isolate a culture and then to perform drug susceptibility. Susceptibility testing using the bactec 460 system. There are important discrepancies between drug susceptibility measured in vitro and the activity of the drug observed in vivo. Antimicrobial susceptibility testing ast is a laboratory procedure performed by medical technologists clinical laboratory scientists to identify. This multicenter study was carried out to evaluate if drug susceptibility testing dst can be successfully carried out directly from processed smearpositive specimens direct dst and if this approach could offer substantial time. Resistance mechanisms and drug susceptibility testing of. Drug susceptibility testing laboratory information tb. Quantitative drug susceptibility testing of mycobacterium. Of particular importance is the concept of efficacy ratios. Antimicrobial susceptibility testing statpearls ncbi bookshelf.
Prediction of dst was obtained from 62% of cases, with complete concordance with phenotypic drug susceptibility reference testing. If the initial testing shows ethionamide resistance, testing at 5 gml and 10 gml is performed. Many methods exist for the in vitro assessment of antimicrobial susceptibility of microorganisms. Direct drug susceptibility testing of mycobacterium. Drug susceptibility testing determines the patients response to various antimicrobics. The goals of testing are to detect possible drug resistance in common pathogens and to assure susceptibility to drugs of choice for particular infections. However, the reliability of dst results obtained through widely used methods does not meet acceptable levels. Antimicrobial susceptibility testing journal of clinical. It has been suggested that, at least in terms of direct relevance to the care of patients with infection, ast may be the. It is not a formal, graded proficiency testing program. Program officers and clinicians may not be aware that the intrinsic accuracy of susceptibility testing results performed under the best circumstances varies with the drug tested.
Novel liquid culturebased drug susceptibility testing techniques have been evaluated. Culturebased phenotypic drug susceptibility testing dst methods are currently the gold standard for drug resistance detection. Use of drugsusceptibility testing for management of drug. Drug susceptibility testing report for march 2019 survey purpose the purpose of this report is to present results of the u. A simple and costsaving phenotypic drug susceptibility. Antimicrobial susceptibility testing, drug resistance mechanisms, and therapy of infections with nontuberculous mycobacteria october 03, 2012 summary moreover, the clinical and laboratory standards institute clsi has published and recently in 2011 updated recommendations including suggested antimicrobial and susceptibility breakpoints. The rate of diffusion of the antimicrobial through the agar is dependent on the diffusion and solubility properties of the drug in mh agar 2 and the. The isolate was first cultured by streaking a swab from the tissue sample on an agar plate.
Susceptibility is determined by evaluating the growth pattern of microorganisms in the presence of an antibiotic. The clinical microbiology laboratory is often a sentinel for detection of drugresistant microorganisms. Susceptibility testing ast results to determine the minimum inhibitory concentration mic values are of high. Among the 308 participants who were culturepositive for m. The table below lists antibacterial drugs and indicates which, if any, susceptibility test interpretive criteria, also known as breakpoints abbreviated as stic, are recognized or. Antimicrobial susceptibility testing, drug resistance mechanisms, and therapy of infections with nontuberculous mycobacteria barbara a. Traditionally, dst for mtbc has relied on the testing of a single, critical concentration cc, which is used to differentiate resistant from susceptible isolates of mtbc and is specific for each antitb agent and. Drug resistance level or susceptibility testing is considered an important issue for the management of newly hiv1 infected and treatmentexposed hiv1 infected patients 9,20. Antimicrobial susceptibility testing by clsi method. As with other dilution methods, etest directly quantifies antimicrobial susceptibility in terms of discrete mic values. The coming of age of drugsusceptibility testing for tuberculosis.
However, the reliability of dst results obtained through widely used methods does not meet. Origin of drug resistance and the criteria for resistance. The growing prevalence of mdrtb around the world places the importance of m. Mycobacterium tuberculosis complex drug susceptibility. Tb drug susceptibility testing determines whether the patients current medications will be effective against the patients tb bacteria. Susceptibility tests determine a microbes vulnerability to antimicrobial drugs by exposing a standardized concentration of organism to specific concentrations of antimicrobial drugs. Pdf an increasing antimicrobial resistance amr has resulted in morbidity and mortality from treatment failures and increased health care. Antibacterial susceptibility test interpretive criteria fda. Intrinsic resistance means that the species was resistant to an antibiotic even before its introduction. The performance of antimicrobial susceptibility testing by the clinical microbiology laboratory is important to confirm. Manual of antimicrobial susceptibility testing national university. Comparative evaluation of the nitrate reduction assay, the.
Rapid drug susceptibility testing plays an important role in the detection and control of mdrxdr tb 23, 31. Drug sensitivity was at the core of individualized cancer chemotherapy in the past. Fdacleared susceptibility test interpretive criteria for delafloxacin disk diffusion zone diameter in mm pathogen susceptible intermediate resistant staphylococcus aureus methicillinresistant and methicillin susceptible isolates. Just like with any antimicrobial susceptibility testing, the results can guide therapy so patient stands the best chance for cure. Antimicrobial susceptibility testing protocols clearly defines the role of the clinical microbiology laboratory in integrated patient care and provides a comprehensive, uptodate procedural manual that can be used by a wide variety of laboratorians. For years, conventional dst on solid egg or agarbased media was a standard technology and is still utilized in. For some organisms, results obtained with one drug predict results with similar drugs.
Drug susceptibility testing dst of mycobacterium tuberculosis is generally carried out after a culture is isolated from a clinical specimen. Table i pdf appendix a pdf appendix b pdf references. May 11, 2020 methods for drug susceptibility testing conventional drug susceptibility testing. Clinical and laboratory standards institute, wayne, pa. Dst for first and secondline antitb drugs was performed using the bactec 460 system as recommended by the manufacturer. Bactec mgit 960 sire kit for the antimycobacterial. Drug resistance mechanisms and drug susceptibility testing. Susceptibility testing can be done for bacteria, fungi, and viruses. Manual of antimicrobial susceptibility testing authors, stephen j. Centers for disease control and prevention cdc model performance evaluation program mpep for mycobacterium tuberculosis complex mtbc drug susceptibility testing survey sent to participants in march 2019. Recent studies have compared newer methodologies with conventional dst for selected slds and. An alternative to detection of mdrtb by a laboratory test is an empirical assumption based on the patients failure to respond to the standard treatment regimen. Technical manual for drug susceptibility testing of medicines.
There are few activities in the clinical microbiology laboratory that utilize more technologist time and laboratory resources than antimicrobial susceptibility testing ast. Mycobacterium tuberculosis drug susceptibility testing. Novel liquid culturebased drugsusceptibility testing techniques have been evaluated. It is welldocumented that tb drugsusceptibility testing dst is one of the most difficult procedures to standardize in the mycobacteriology laboratory 5. Modifications can include the addition of any substance e. Antimicrobial susceptibility testing, drug resistance. Evaluation of a rapid molecular drugsusceptibility test. Traditionally, dst for mtbc has relied on the testing of a single, critical concentration cc, which is used to differentiate resistant from susceptible isolates of mtbc and is specific for each antitb agent and test method. These methods are usually suitable for testing up to 25 antibiotics for a given sample. Susceptibility testing infectious diseases merck manuals. Conventional indirect drug susceptibility testing of mycobacterium tuberculosis with liquid medium is well established and offers timesaving and reliable results.
308 828 980 730 861 404 152 834 736 1174 1103 644 91 525 660 1214 810 1362 1085 1123 530 414 182 1278 1043 601 121 1464 803 1272 855 878 1470 315 1363