What is phenotypic drug resistance?

What is phenotypic drug resistance?

However, in some situations resistance can be achieved without any genetic alteration; this is called phenotypic resistance. Non-inherited resistance is associated to specific processes such as growth in biofilms, a stationary growth phase or persistence.

How do you test for drug resistance?

The standard method for identifying drug resistance is to take a sample from a wound, blood or urine and expose resident bacteria to various drugs. If the bacterial colony continues to divide and thrive despite the presence of a normally effective drug, it indicates the microbes are drug-resistant.

What is DST in TB?

Drug susceptibility testing (DST) of Mycobacterium tuberculosis is generally carried out after a culture is isolated from a clinical specimen. This takes a long time, first to isolate a culture and then to perform drug susceptibility testing (indirect DST).

What are genotypic tests?

Genotypic Assay. A type of resistance test that detects drug-resistant mutations in HIV genes. Resistance testing is used to guide selection of an HIV regimen when initiating or changing antiretroviral therapy (ART).

What is a resistance test?

An insulation resistance (IR) test measures the total resistance between any two points separated by electrical insulation. Such tests are useful for checking the quality of insulation, not only when a product is first manufactured but also over time as the product is used.

What are the purposes of doing drug sensitivity tests for TB?

When performed properly, this method allows a quantitation of the proportion of mutants resistant to a drug and can detect the 1% proportion of drug- resistant mutants above which therapeutic failure is likely. M. tuberculosis complex are tested by this method with the following drugs: Isoniazid.

Is XDR TB treatable?

XDR-TB is associated with a much higher mortality rate than MDR-TB, because of a reduced number of effective treatment options. A 2008 study in the Tomsk oblast of Russia, reported that 14 out of 29 (48.3%) patients with XDR-TB successfully completed treatment.

What is a genotypic resistance test?

Genotypic resistance testing examines the genetic structure (genotype) of a patient’s HIV. A blood sample is taken from the patient, and the HIV is analyzed for the presence of specific genetic mutations that are known to cause resistance to specific drugs.

How are phenotypic assays used to test for drug resistance?

Phenotypic assays measure the ability of a virus to grow in different concentrations of ARV drugs. RT, PR, and, more recently, IN and envelope gene sequences derived from patient plasma HIV RNA are inserted into the backbone of a laboratory clone of HIV or used to generate pseudotyped viruses that express the patient-derived HIV genes of interest.

What kind of testing is used for drug resistance?

Standard genotypic drug-resistance testing in ARV-naive persons involves testing for mutations in the reverse transcriptase (RT) and protease (PR) genes. If transmitted integrase strand transfer inhibitor (INSTI) resistance is a concern, providers should ensure that genotypic resistance testing also includes the integrase gene (AIII).

When to do drug resistance testing for HIV?

HIV drug-resistance testing is recommended at entry into care for persons with HIV to guide selection of the initial antiretroviral therapy (ART) regimen (AII). If therapy is deferred, repeat testing may be considered at the time of ART initiation (CIII).

How are phenotypic drug susceptibility tests ( DST ) used?

3.3 Phenotypic drug susceptibility tests (DST) Phenotypic DST determines if a strain is resistant to an anti-TB drug by evaluating the growth (or metabolic activity) in the presence of the drug8.

Phenotypic assays measure the ability of a virus to grow in different concentrations of ARV drugs. RT, PR, and, more recently, IN and envelope gene sequences derived from patient plasma HIV RNA are inserted into the backbone of a laboratory clone of HIV or used to generate pseudotyped viruses that express the patient-derived HIV genes of interest.

Standard genotypic drug-resistance testing in ARV-naive persons involves testing for mutations in the reverse transcriptase (RT) and protease (PR) genes. If transmitted integrase strand transfer inhibitor (INSTI) resistance is a concern, providers should ensure that genotypic resistance testing also includes the integrase gene (AIII).

How is Genotypic resistance used to test for HIV?

HIV genotypic resistance is a qualitative test and detects mutations associated with drug resistance. It does not report the level of resistance associated with the drug. Phenotypic resistance testing is a better indicator of the level of HIV drug resistance.

HIV drug-resistance testing is recommended at entry into care for persons with HIV to guide selection of the initial antiretroviral therapy (ART) regimen (AII). If therapy is deferred, repeat testing may be considered at the time of ART initiation (CIII).