What is the d test for clindamycin?

A positive D test (see Figure) indicates the presence of macrolide-inducible resistance to clindamycin produced by an inducible methylase that alters the common ribosomal binding site for macrolides, clindamycin and the group B streptogrammins (quinupristin) (Woods, 2009) .

When do we use D test?

D test is a simple disc diffusion test giving high throughput results. It is used to study the macrolide lincosamide streptogramin resistance (MLSB), both constitutive and inducible as well as macrolide streptogramin resistance (MSB) in Staphylococcus aureus.

What is the plate media used to confirm the clindamycin induced resistance?

Inducible resistance to clindamycin was tested by ‘D test’ as per CLSI guidelines. [7] Briefly, erythromycin (15 μg) disc was placed at a distance of 15 mm (edge to edge) from clindamycin (2 μg) disc on a Mueller-Hinton agar plate, previously inoculated with 0.5 McFarland standard bacterial suspensions.

Why do we need to do the D test for MRSA isolates?

MRSA isolates with inducible clindamycin resistance (iCR) are resistant to erythromycin and sensitive to clindamycin on routine testing. D-test can help to determine whether clindamycin could be used as a therapeutic option2.

What is D-zone test?

To test for clindamycin resistance certain strains of Staphylococcus aureus bacteria with natural resistance to erythromycin are chosen for cultivation on the gel. The two antimicrobial disks contain erythromycin and clindamycin and are placed about 20 mm apart. This is called a D-zone test, or D test.

How do I set up my D test?

Procedure for D-zone Test Put clindamycin (2-μg ) and erythromycin (15-μg ) disks approximately 15 mm apart (measured edge to edge). For beta-hemolytic streptococci and S. pneumoniae, place disks 12 mm apart. Invert plates and incubate the plate for 16 to 18 hours at 35°C.

Which test is used for the determination of inducible clindamycin resistance in staphylococci and streptococci?

Inducible clindamycin resistance can be detected with a simple disk approximation test, commonly referred as the D test [14]. For this test, an erythromycin disk is placed 15 mM to 26 mM (edge to edge) from a clindamycin disk in a standard disk diffusion test.

What test is used to distinguish between staphylococci and streptococci?

The catalase test is important in distinguishing streptococci (catalase-negative) staphylococci which are catalase positive. The test is performed by flooding an agar slant or broth culture with several drops of 3% hydrogen peroxide.

What is D zone test?

Does clindamycin cover MRSA?

Clindamycin is widely used in children for community-acquired MRSA skin and soft-tissue infections, and is anecdotally reported to be effective.

What is D-Zone in microbiology?

Which tests could be used to distinguish between Staphylococcus aureus and Staphylococcus epidermidis?

aureus and Staph. epidermidis. Accordingly, a multiplex PCR was developed and we found that a single gene encoding the adhesin fibrinogen binding protein could be used to identify and differentiate the two species. Consequently, a multiplex reaction combining a triplex PCR for Staph.

What is a positive D test for clindamycin?

The inhibition of bacterial growth in zone 2 but not zone 1 produces a “D” shape surrounding the clindamycin disk, which is considered a “positive” D-test. (Adapted from Woods 2009).

How do you test for clindamycin resistance?

Inducible Clindamycin Resistance (D Test): Principle, procedure and Interpretation. D test is performed by disk diffusion, placing a 15-μg Erythromycin disk in proximity to a 2-μg Clindamycin disk on an agar plate that has been inoculated with a staphylococcal isolate; the plate is then incubated overnight.

What is the induction test for clindamycin?

For Erythromycin-resistant isolates, induction tests can help laboratories determine whether results for Clindamycin should be reported as susceptible (when the induction test is negative) or as resistant (when the induction test is positive). Procedure: Materials Large (15 X 150mm) Mueller Hinton Plate

What is the D phenotype of clindamycin?

A clear, D-shaped zone of inhibition around the Clindamycin disk is designated as the D phenotype which is labeled as D or D+. Four other non-induction phenotypes (designated as negative [Neg], hazy D zone [HD], resistant [R], and susceptible [S]) are also observed in disk diffusion results