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Standards for Microbiology Investigations (UK SMIs)

UK Standards for Microbiology Investigations (UK SMIs) are a comprehensive referenced collection of recommended algorithms and procedures for clinical microbiology.

UK Health Security Agency (UKHSA) in conjunction with its partner organisations develops UK SMIs to help to assure equivalence of investigation strategies in different laboratories; all the UK SMI Test Procedures (TPs) for bacteriology stipulate the use of control strains from the National Collection of Type Cultures (NCTC). Controls are necessary to help demonstrate that laboratory procedures are being operated and interpreted correctly.

You can view the UK Standards for Microbiology Investigations document to see example reference strains for UK Standards for Microbiology Investigations test procedures. For further information or to download any of the Standards for Microbiological Investigations go to the RCPath’s UK Standards for Microbiology Investigations webpage.

Culture Collections now provide a cost-effective means for clinical microbiology laboratories to update their stock cultures of the 17 NCTC strains needed for the SMI TPs in a single order. The SMI TP NCTC set includes controls listed below.

 

UK SMI

Example reference strain for both phenotypic and EUCAST disc susceptibility tests

 

Bacteria 

Alternative bacteria  

Fungi

TP 2 – Aesculin hydrolysis test

Positive control

Negative control

Enterococcus faecalis NCTC 12697

Streptococcus agalactiae NCTC 8181

   

TP 3 – Agglutination test

Positive control

Negative control

 

N/A **

 

   

TP 5 – Bile solubility test

Positive control

Negative control

Streptococcus pneumoniae NCTC 12977

Streptococcus mitis NCTC 10712

   

TP 8 – Catalase test***

Positive control

Negative control

Staphylococcus aureus NCTC 6571

Streptococcus mitis NCTC 10712

Staphylococcus aureus NCTC 12973

 

Cryptococcus neoformans NCPF 3168


Candida albicans NCPF 3281

TP 10 – Coagulase test

Positive control

Negative control

Staphylococcus aureus NCTC 6571

Staphylococcus haemolyticus NCTC 11042

 

Staphylococcus aureus NCTC 12973

 

 

TP 12 – Deoxyribonuclease test

Positive control

Negative control

Staphylococcus aureus NCTC 6571

Staphylococcus haemolyticus NCTC 11042

Staphylococcus aureus NCTC 12973

 

 

TP 19 – Indole test

Positive control

Negative control

Escherichia coli NCTC 10418

Proteus mirabilis NCTC 10975

Escherichia coli NCTC 12241

 

 

TP 21 – Motility test

Positive control

Negative control

Proteus mirabilis NCTC 10975

Acinetobacter lwoffii NCTC 5866

   

TP 24 - ONPG (ß-Galactosidase) test (for Enterobacteriaceae)

Positive control

Negative control

Escherichia coli NCTC 10418

Proteus mirabilis NCTC 10975

Escherichia coli NCTC 12241 

 

 

TP 24 - ONPG (ß-Galactosidase) test (for Neisseria species)

Positive control

Negative control

Neisseria lactamica NCTC 10617

Neisseria gonorrhoeae NCTC 8375

   

TP 25 – Optochin test

Positive control

Negative control

Streptococcus pneumoniae NCTC 12977

Streptococcus mitis NCTC 10712

   

TP 26 – Oxidase test***

Positive control

Negative control

Pseudomonas aeruginosa NCTC 10662

Escherichia coli NCTC 10418

Pseudomonas aeruginosa NCTC 12903


Escherichia coli NCTC 12241

Candida albicans NCPF 3281


Saccharomyces cerevisiae NCPF 8348

TP 27 - Oxidation/fermentation of glucose test (Gram negative roots)

 

Oxidation:

Positive control

Negative control

Pseudomonas aeruginosa NCTC 10662

Acinetobacter Iwoffii NCTC 5866

Pseudomonas aeruginosa NCTC 12903

 

 

Fermentation:

Positive control

Negative control

Escherichia coli NCTC 10418

Acinetobacter Iwoffii NCTC 5866

Escherichia coli NCTC 12241

 

 

TP 27 - Oxidation/fermentation of glucose test (Gram positive cocci)

 

Oxidation:

Positive control

Negative control

Micrococcus luteus NCTC 2665


OF basal medium without carbohydrate

   

Fermentation:

Positive control

Negative control

Staphylococcus aureus NCTC 6571

OF basal medium without carbohydrate

Staphylococcus aureus NCTC 12973

 

 

P 29 – Porphyrin synthesis (ALA) test

Positive control

Negative control

Haemophilus parainfluenzae NCTC 10665

Haemophilus influenzae NCTC 11931

Haemophilus influenzae NCTC 12975

 

 

TP 30 - Potassium hydroxide test

Positive control

Negative control

Escherichia coli NCTC 10418

Staphylococcus aureus NCTC 6571

Escherichia coli NCTC 12241


Staphylococcus aureus NCTC 12973

 

TP 32 - Changing the phase pf Salmonella

Positive control

Negative control

N/A**

   

TP 34 – Thermonuclease test*

Positive control

Negative control

Staphylococcus aureus NCTC 6571

Staphylococcus haemolyticus NCTC 11042

Staphylococcus aureus NCTC 12973

 

 

TP 36 – Urease test***

Positive control

Negative control

Proteus mirabilis NCTC 10975

Escherichia coli NCTC 10418

Escherichia coli NCTC 12241

 

Cryptococcus neoformans NCPF 3168


Candida albicans NCPF 3281

TP 38 – X and V factor test

 

 

X and V factor

Haemophilus influenzae NCTC 11931

Haemophilus influenzae NCTC 12975

 

 

V factor only

Haemophilus parainfluenzae NCTC 10665

   

X factor only

Haemophilus haemoglobinophilus NCTC 8540

   

TP39 – Staining procedures

Positive control

Negative control

Use the recommended controls within . However, if controls used are other than those recommended, laboratories should ensure that these are validated prior to use.

   

TP40 - MALDI TOF MS test procedure 

Positive control

Negative control

The quality control organisms used is dependent on what the manufacturer provides. Follow manufacturer’s instructions. Laboratories should include their own validated positive and negative controls.

   

*The reference bacterial strains have not been validated by NCTC for the test shown.
**N/A – Not Applicable
*** The reference fungal strains have not been validated by NCTC for the tests at the time of publication.

There is validation data for all the strains tested.

Those listed as “alternative strains” in this table are also EUCAST control strain, and are suitable for use for both purposes.