StrepPRO™ Grouping Kit

Cat. no. PL030HD StrepPRO™ Grouping Kit 60 tests/kit
Each kit contains:
*     PL031HD     Blue Latex Suspension Group A, 3ml 1 vial/kit
*     PL032HD     Blue Latex Suspension Group B, 3ml 1 vial/kit
*     PL033HD     Blue Latex Suspension Group C, 3ml 1 vial/kit
*     PL034HD     Blue Latex Suspension Group D, 3ml 1 vial/kit
*     PL035HD     Blue Latex Suspension Group F, 3ml 1 vial/kit
*     PL036HD     Blue Latex Suspension Group G, 3ml 1 vial/kit
*     PL037HD     Extraction Reagent 1, 3.5ml 1 vial/kit
*     PL038HD     Extraction Reagent 2, 3.5ml 1 vial/kit
*     PL039HD     Extraction Reagent 3, 8.5ml 2 vials/kit
*     PL040HD     Polyvalent Positive Control, 3.5ml 1 vial/kit
*     PL092HD     Latex Test Cards 48 cards/kit
*     Mixing Sticks 300 sticks/kit
*     Components also available separately.

INTENDED USE

Hardy Diagnostics StrepPRO™ Grouping Kit provides a rapid latex agglutination method for the serological identification of Lancefield's groups A, B, C, D, F, and G from isolated colonies of beta-hemolytic Streptococcus spp. and Enterococcus faecalis.

SUMMARY

Clinical, epidemiological, and microbiological studies have conclusively shown that the diagnosis of streptococcal infections based on clinical symptoms always require microbiological verification.(4) Beta-hemolytic streptococci are the most frequently isolated human pathogens among the representatives of the genus Streptococcus. Nearly all the beta-hemolytic streptococci possess specific carbohydrate antigens, known as streptococcal grouping antigens. Previously Lancefield showed that these antigens can be extracted in soluble form and identified by precipitation reactions with homologous antisera. Currently different procedures for extraction of streptococcal antigens are in use.(1,2,6,7)

Hardy Diagnostics StrepPRO™ Grouping Kit liberates the specific antigen from the bacterial cell wall using a modified nitrous acid extraction. The extracted antigen, in conjunction with latex agglutination, offers a rapid, sensitive, and specific method for identification of streptococcal groups A, B, C, D, F, and G from primary culture plates. Extraction Reagents 1 and 2 contain a chemical substance able to extract the streptococcal group specific antigens at room temperature. Extraction Reagent 3 contains a neutralizing solution. The neutralized extracts can then be easily identified using blue latex particles sensitized with purified group specific rabbit immunoglobulins. These blue latex particles agglutinate strongly in the presence of homologous antigen and will not agglutinate when homologous antigen is absent.

MATERIALS SUPPLIED

Blue Latex Suspension Group A Blue latex particles coated with purified rabbit antibodies to group A streptococci, suspended in phosphate buffer with 0.1% sodium azide
Blue Latex Suspension Group B Blue latex particles coated with purified rabbit antibodies to group B streptococci, suspended in phosphate buffer with 0.1% sodium azide
Blue Latex Suspension Group C Blue latex particles coated with purified rabbit antibodies to group C streptococci, suspended in phosphate buffer with 0.1% sodium azide
Blue Latex Suspension Group D Blue latex particles coated with purified rabbit antibodies to group D streptococci, suspended in phosphate buffer with 0.1% sodium azide
Blue Latex Suspension Group F Blue latex particles coated with purified rabbit antibodies to group F streptococci, suspended in phosphate buffer with 0.1% sodium azide
Blue Latex Suspension Group G Blue latex particles coated with purified rabbit antibodies to group G streptococci, suspended in phosphate buffer with 0.1% sodium azide
Extraction Reagent 1 Extraction Reagent 1 with 0.1% sodium azide
Extraction Reagent 2 Extraction Reagent 2
Extraction Reagent 3 Extraction Reagent 3 with 0.1% sodium azide
Polyvalent Positive Control Polyvalent Extract with antigens from inactivated streptococcal groups A, B, C, D, F, and G
Latex Test Cards Disposable white cards with ten raised reaction circles
Mixing Sticks Disposable 4 inch wooden sticks

MATERIALS REQUIRED BUT NOT PROVIDED

Standard microbiological supplies and equipment such as loops, pasteur pipettes, 12x75mm test tube, timers, other culture media, swabs, applicator sticks, incinerators, and incubators, etc., as well as serological and biochemical reagents, are not provided.

STORAGE AND SHELF LIFE

Storage: Upon receipt store at 2-8°C away from direct light. Do not freeze. This kit, or any of its reagents, should not be used if there are any signs of discoloration, contamination, or if the expiration date has passed.

PRECAUTIONS

The Blue Latex Reagents, Extraction Reagent 1, and Extraction Reagent 3 contain sodium azide as a preservative. Sodium azide can react explosively with copper or lead if allowed to accumulate. Although the amount of sodium azide in the reagents is minimal, large quantities of water should be used when flushing these reagents down the sink.

Extraction Reagents 1, 2, and 3 contain a caustic agent. In case of skin contact, immediately wash with soap and copious amounts of water. In case of eye contact, flush for at least 15 minutes with water.

PROCEDURE

Specimen Collection:
For specific procedures regarding specimen collection and preparation of primary cultures consult standard microbiological references.(4,10-12)

In general, an overnight, gram-positive, beta-hemolytic isolate of streptococcal isolate is required for use in this assay. Colonies should be chosen from an area demonstrating obvious isolation. One to four isolated colonies are recommended for grouping testing, however, if colonies are pinpoint, an increased number of colonies, approximately a loopful, should be used.

Test Protocol:

1. Allow all reagents to acclimatize to room temperature for 10 minutes prior to use.

2. Label one 12x75mm test tube for each specimen tested.

3. Add one drop of Extraction Reagent 1 to each tube.

4. Using a loop, select 1 to 4 isolated beta-hemolytic colonies and suspend them in Extraction Reagent 1. If colonies are minute, pick a loopful of colonies, such that the Extraction Reagent 1 becomes turbid.

5. Add one drop of Extraction Reagent 2 to each tube.

6. Mix the reaction by tapping the tube with a finger for 10 seconds.

7. Add five drops of Extraction Reagent 3 to each tube. Mix the reaction as in step 6.

8. Prior to use, resuspend the Blue Latex Reagents, by inverting the tubes. Dispense one drop of each blue latex suspension onto separate circles on the test card.

9. Using a pasteur pipette, place one drop of the extract suspension next to the drop of latex suspension in each circle. Ensure that the pipette tip does not touch the latex suspension.

10. Mix the blue latex and the extract with the wooden sticks provided, using the complete area of the circle. A new stick should be used for each reagent.

11. Gently hand rock the entire card, allowing the mixture to flow slowly within the ring area.

12. At one minute, under normal lighting conditions, observe for agglutination, or strong clumping, of the blue latex particles. See Interpretation of Results for more information.

INTERPRETATION OF RESULTS

Positive Results:
A rapid and significantly strong clumping of the blue latex particles, to form an agglutination pattern, with only one of the latex reagents indicates an identification of the streptococcal isolate for the Lancefield group.

A weak reaction with a single blue latex reagent should be repeated using a heavier inoculum. The repeated test is considered positive if a visible agglutination occurs with only one of the blue latex reagents.

Negative Results:
No visible agglutination of the latex particles indicates a negative reaction for the particular Lancefield group.

FLOW CHART

Figure 1: Suggested Scheme for Streptococcal Grouping:


Streptococcal Grouping

LIMITATIONS

This kit is intended for use in the identification of beta-hemolytic streptococci. If alpha or gamma streptococci are identified, the identification should be confirmed by biochemical tests. See flow chart for the recommended procedure for grouping streptococci.(5,9)

Do not perform the procedure using a broth culture as false reactions can occur.

False-negative or false-positive results can occur if inadequate amounts of culture or Extraction Reagents are used.

False-positive reactions have been known to occur with organisms from unrelated genera, including gram-negatives such as Escherichia coli, Klebsiella, and Pseudomonas species. These are likely to non-specifically agglutinate all latex reagents. This kit is recommended only for testing of gram-positive organisms.

Listeria monocytogenes may cross react with the Streptococcal Latex Reagents Group B and/or Group G, since L. monocytogenes exhibits similar antigenicity to group B and G streptococci. The catalase test may be performed to distinguish between Listeria, which are catalase-positive, and streptococci, which are catalase-negative. Gram staining and motility testing may be performed as further aids in differentiation.

Some rare strains of group D streptococci have been found to cross react with group G antisera. These strains may be confirmed as group D by a positive Bile Esculin (Cat. no. G12 or L10) test.

QUALITY CONTROL

The following organisms are routinely tested on each lot of StrepPRO™ Grouping Kit by the manufacturer:

Test Organisms Inoculation Method* Incubation Results
Time Temperature Atmosphere
Streptococcus pyogenes
ATCC® 19615
* 1 min. 35°C Aerobic or CO 2** Agglutination observed only with Blue Latex Suspension Group A
Streptococcus agalactiae
(Group B)
ATCC® 12386

* 1 min. 35°C Aerobic or CO2** Agglutination observed only with Blue Latex Suspension Group B
Streptococcus spp.
(Group C)
ATCC® 12388

* 1 min. 35°C Aerobic or CO2** Agglutination observed only with Blue Latex Suspension Group C
Enterococcus faecalis
ATCC® 19433
* 1 min. 35°C Aerobic or CO2** Agglutination observed only with Blue Latex Suspension Group D
Streptococcus spp.
(Group F)
ATCC® 12392

* 1 min. 35°C Aerobic Agglutination observed only with Blue Latex Suspension Group F
Streptococcus spp.
(Group G)
ATCC® 12394

* 1 min. 35°C Aerobic Agglutination observed only with Blue Latex Suspension Group G

In addition, each Blue Latex Suspension is tested for the absence of cross-reactions against extracts of the following
additional quality control organisms:

Test Organisms Inoculation Method* Incubation Results
Time Temperature Atmosphere
Escherichia coli
ATCC® 25922
* 1 min. 35°C Aerobic or CO2** No agglutination observed with any Blue Latex Suspensions
Klebsiella pneumoniae
ATCC® 13883
* 1 min. 35°C Aerobic or CO2** No agglutination observed with any Blue Latex Suspensions
Staphylococcus aureus
ATCC® 25923
* 1 min. 35°C Aerobic or CO2** No agglutination observed with any Blue Latex Suspensions
Haemophilus influenza
Type B
ATCC® 10211

* 1 min. 35°C Aerobic or CO2** No agglutination observed with any Blue Latex Suspensions

* Refer to the section entitled Procedure for a detailed description of the inoculation protocol.

** Atmosphere of incubation is enriched with 5-10% CO2.

StrepPRO™ Grouping Kit

StrepPRO™ Grouping Kit. Showing agglutination (LEFT) and no agglutination (RIGHT).

END USER QUALITY CONTROL

Latex Suspension
Verify the performance of each Latex Suspension by agglutinating with the Polyvalent Positive Control (included in the kit).
Expected Results: positive agglutination.

Extraction Reagents
Verify the performance of Extraction Reagents 1, 2, and 3 with S. pyogenes ATCC® 19615. Agglutinate the extract with the Latex Suspension Group A that was previously approved in the step above.
Expected Results: positive agglutination.

Absence of Autoagglutination
Verify the lack of autoagglutination by performing the test procedure on one of the Latex Reagents without adding bacteria or the Polyvalent Positive Control to the Extraction Reagents.
Expected Results: negative agglutination.

PERFORMANCE CHARACTERISTICS

A. Cross Reactivity Studies:

Hardy Diagnostics StrepPRO™ Grouping Kit was tested for cross-reactivity using 33 ATCC® reference strains. The kit successfully grouped all streptococci containing Lancefield groups A, B, C, D, F, and G (N=16). No cross-reactivity was observed during the testing of other streptococcal strains (N=7) nor of other non-streptococcal organisms (N=10).

B. Clinical Performance Studies:

Hardy Diagnostics StrepPRO™ Grouping Kit was evaluated at a Microbiological Center in Oxford, England. In this study 468 primary culture were tested by the StrepPRO™ Grouping Kit and an alternative grouping kit. Overall agreement between the two kits upon first time testing occurred with 452 of 468 isolates tested (96.6%). Anomalous results (N=16; all minute colonies) were repeated using a heavier inoculum. 13 of the 16 anomalous results agreed after retest which included 1 group A, 2 group B, 3 group D, 1 group F, 5 group G, and 1 non-groupable strains. Two of the 3 discrepant strains were further identified as non-beta-hemolytic strains, while the third isolate grouped as group D by StrepPRO™ Grouping Kit, while determined non-groupable by the alternative kit. This isolate gave a positive group D isolate result with the alternative kit following subculture. Overall agreement between the StrepPRO™ Grouping Kit and the alternative grouping kit after retest of anomalous results occurred with 463 of 468 isolates tested (99.4%). The 468 Streptococci isolates used in this study included 127 group A, 93 group B, 30 group C, 28 group D, 8 group F, 107 group G, and 75 non-groupable strains.

A second performance study was carried out a Health Center in Ontario, Canada. In this study, 111 primary cultures were included (110 tested, 1 inadequate). All the strains were originally grouped by Lancefield precipitation reactions. All group D were further biochemically confirmed using Bile Esculin and PYR assay protocol. The primary cultures were tested in parallel using the StrepPRO™ Grouping Kit and an alternative grouping kit. In this study, the overall agreement between StrepPRO™ Grouping Kit and the Lancefield results occurred with 109 of the 110 isolates tested (99%), while overall agreement between the alternative kit and Lancefield results occurred with 106 of 110 isolates tested (96.3%). The 110 Streptococci primary isolates used in this study included 15 group A, 40 group B, 13 group C, 4 group D, 11 group F, 12 group G, and 15 non-groupable strains.

REFERENCES

1. Edereer, G.M., et al. 1972. Rapid Extraction Methods with Pronase B for Grouping Beta-Hemolytic Streptococci. Appl. Microbiol.; 23, 285.

2. E.L. Kholy, et al. 1974. Simplified Extraction Procedure for Serological Grouping of Beta-Hemoltyic Streptococci. Appl. Microbiol.; 28, 836.

3. Elliot, S.D., et al. 1978. The Type-Specific Polysaccharides of Streptococcus suis. J. Exp. Med.; 148, 1699.

4. Versalovic, J., et al. Manual of Clinical Microbiology. American Society for Microbiology, Washington, D.C.

5. Facklam, R.R. 1977. Physiological Differentiation of Viridans Streptococci. J. Clin. Microbiol.; 5, 184.

6. Fuller, A.T. 1938. The Formamide Method for the Extraction of Polysaccharides from Hemolytic Streptococci. Brit. J. Exp. Path.; 19, 130.

7. Maxted, W.R. 1948. Preparation of Streptococcal Extracts for Lancefield Grouping. Lancet, ii, 255.

8. Nowlan, S.S., and Deibel, R.H. 1967. Group Q Streptococci. I. Ecology, Serology, Physiology and Relationships to Established Enterococci. J. Bact.; 94, 291.

9. Petts, D.N. 1984. Early Detection of Streptococci in Swabs by Latex Agglutination Before Culture. J. Clin. Microbiol.; 19, 432.

10. Tille, P.M., et al. Bailey and Scott's Diagnostic Microbiology, C.V. Mosby Company, St. Louis, MO.

11. Isenberg, H.D. Clinical Microbiology Procedures Handbook, Vol. I, II & III. American Society for Microbiology, Washington, D.C.

12. Koneman, E.W., et al. Color Atlas and Textbook of Diagnostic Microbiology. J.B. Lippincott Company, Philadelphia, PA.


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