23 replies to this topic

[Petersen_M]

Hello Everyone

 

I am editing a testing schedule and on the schedule it states test for Staphylococcus aureus and Coliforms for hand swabs. It also then states test for E.coli only if Coliforms are positive. Is this correct? The problem I have with this statement is that swabs need to be tested within 24 hours of it being sampled. A specific swab can also NOT be re-tested. So how is it possible to test for E.coli if Coliforms are positive? By then the staff member would have washed their hands clean. I was thinking perhaps take Coliforms off the schedule and test only for E.coli instead. The other alternative would be to test for everything.What do you all think?

 

Michelé

[Petersen_M]

Unless we swab hands twice and store swab number 2 in refrigeration?

[BrummyJim]

Your lab will tell you that you need two swabs to test for coliforms and e-coli. You can test for staph and coliforms from a single swab as they take a similar approach in the lab. E-coli is a different type of test.

[Charles.C]

Hello Everyone

 

I am editing a testing schedule and on the schedule it states test for Staphylococcus aureus and Coliforms for hand swabs. It also then states test for E.coli only if Coliforms are positive. Is this correct? The problem I have with this statement is that swabs need to be tested within 24 hours of it being sampled. A specific swab can also NOT be re-tested. So how is it possible to test for E.coli if Coliforms are positive? By then the staff member would have washed their hands clean. I was thinking perhaps take Coliforms off the schedule and test only for E.coli instead. The other alternative would be to test for everything.What do you all think?

 

Michelé

Hi PetersenM,

 

Its micro.logic

(generic) E.coli is a member of the Coliform group.

No detection of Coliform  implies no presence of E.coli.

Positive detection of coliforms requires continuation to E.coli test

 

I do not know yr procedure but traditionally the procedure for E.coli is an extension of that for coliforms, ie one sample/sequence of tests enables both together.

 

Have a look at BAM -

 

http://www.fda.gov/F...s/ucm064948.htm

 

I would hope that the details for use of yr swab would give an appropriate procedure.

[RG3]

There are also the 3M petrifilms available that test for both coliform and E.coli http://solutions.3m....Vbe29BDXSBJ7Fgl

 

You can't inoculate off a 3M petrifilm from a coliform plate onto a E.coli plate. So the test needs to be done from the beginning. 

[Charles.C]

There are also the 3M petrifilms available that test for both coliform and E.coli http://solutions.3m....Vbe29BDXSBJ7Fgl

 

You can't inoculate off a 3M petrifilm from a coliform plate onto a E.coli plate. So the test needs to be done from the beginning. 

Hi RG3,

 

I tried the (combined) Coliform/E.coli Petrifilm product some time ago but gave it up due not sensitive enough for E.coli at low levels.

(Common problem for  non-MPN based systems).

 

Maybe OK if major contamination.

[ennyk]

Our testing includes a combined test of CEC and E.coli, whereby when there is positive CEC result, further testing for E.coli on the same sample will be carried out. try Biomedix chemicals.

[carine]

Hi Jim,

Is Staphylococcus aureus and Coliforms under same group? Negative result for staphy means no presence of Coliform?

[Petersen_M]

We outsource our swabs. We test for Staph and for Coliforms separately not under the same group. Thus only one swab will be taken and both coliforms and staph would be tested from that particular swab.Our schedule states that if the results are positive for Coliforms.. we should do an extensive test for E.coli. I fully understand that E.coli is a member of the coliform group. However, by the time results for coliforms are reported, that very swab cannot be tested again for E.coli. An extensive test cannot be done on a swab sample taken 2 days prior can it? We have not heard of petrifilms being used in S.A I stand under correction. I will try Biomedix chemicals .

[BrummyJim]

Hi,

 

On further investigation, I was wrong. You can test for Coliforms, Staph and e-coli from the same swab. However in general a swab can only be tested within 24 hours of being taken, so either you commission all tests, or re-swab with all the associated issues.

 

Sorry.

[Charles.C]

We outsource our swabs. We test for Staph and for Coliforms separately not under the same group. Thus only one swab will be taken and both coliforms and staph would be tested from that particular swab.Our schedule states that if the results are positive for Coliforms.. we should do an extensive test for E.coli. I fully understand that E.coli is a member of the coliform group.

However, by the time results for coliforms are reported, that very swab cannot be tested again for E.coli. An extensive test cannot be done on a swab sample taken 2 days prior can it? 

Pls refer the BAM Procedure. The Procedure sample > coliform > E.coli is continuous, albeit recursive. Condensed versions of BAM also exist.

We have not heard of petrifilms being used in S.A I stand under correction. I will try Biomedix chemicals .

 

@Carine - S.aureus is a species, not a Group. "Coliform" is a (functionally defined) Group. And No times 2.

 

@ ennyk - What is CEC ? New species ?

The Biomedix product maybe something like Hygiena's Microsnap ?. Interesting looking concept if it works and <10 result is satisfactory.

[Antores]

I don’t know what your operation is, and why it would require testing hands for coliforms and stapah, but it seems like a waste of resources for me, unless is done as validation for a hand washing process, or may be part of your hiring requirements to be sure new employees are staph free?

May be this is a normal procedure in your industry and geographical area, but what is the purpose of that? How long it takes to get results on coliforms, and what the employee does during that time? and if it comes positive.. What is the corrective action? All I see they can do is wash their hands again anyways..

I’m trying to understand why you are not doing ATP testing instead, get result instantly, and if results are out of the stablished range, then re-wash hands immediately (re-train if necessary) and re-test.. The whole process may take just 5 minutes.

Again, Just trying to understand why are you doing that..

[Petersen_M]

I agree with you @Antores which is why I myself am having trouble with that. Our new Technical Manager said the same thing about the ATP testing.  The swabbing is done for validation of hand washing process. @Charles C I will have a look again.

[Charles.C]

It depends on the Product/Process but S.aureus is a (UK) recommended check for hands of workers involved with chilled, RTE foods. Requirement is no repetitive detection. Reason is enhanced opportunity for growth post heat treatment.

 

 If you have an in-house lab, ATP is probably more expensive than conventional swabbing. And possibly more numerically contentious.

[w.weber]

Hello,

I am not really familiar with ATP, but does a swab of the hands not also show the normal human cells you may grab with the swab?

I know ATP for testiong machines, but I think for humans it may not be very realistic.

Yours

Werner

[RG3]

W.weber, you may not be familiar with ATP, but you definitely understand the science behind it. You're correct, no matter how you clean your hands you will always pick up a count on the ATP machine. Validated & Verified.

[JThompson]

We use a standard plate count for hand swabs.  Further identification for suspected staph or E. coli could then be carried out from growth on that plate.  When we use MPN tubes, there are secondary steps that use the sample growing within the tubes to be tested for the E. coli.

 

Petrifilm options are ok except for sensitivity issues.

 

ATP swabs "could" be an acceptable route if you first studied and verified the normal range of count on a known clean hand before using to check for out of specification, however this would be time consuming.

[Charles.C]

We use a standard plate count for hand swabs.  Further identification for suspected staph or E. coli could then be carried out from growth on that plate.  When we use MPN tubes, there are secondary steps that use the sample growing within the tubes to be tested for the E. coli.

 

Petrifilm options are ok except for sensitivity issues.

 

ATP swabs "could" be an acceptable route if you first studied and verified the normal range of count on a known clean hand before using to check for out of specification, however this would be time consuming.

 

Hi jthompson,

 

I don't know what plate count medium you are using but unless customised it seems unlikely to be optimised for growth of S.aureus and, to a perhaps lesser extent, E.coli. And particularly at the hopefully low expected levels.

 

For example here is one direct swab route to S.aureus -

http://www.ncbi.nlm....les/PMC2884472/

[Antores]

Hello,

I am not really familiar with ATP, but does a swab of the hands not also show the normal human cells you may grab with the swab?

I know ATP for testiong machines, but I think for humans it may not be very realistic.

Yours

Werner

 

@ AIFSQN and SIFSQN...

 

Right, ATP It does not detect bacteria but Adenosine triphosphate, and if what you need to detect is bacteria, then is totally useless, but of course ATP has its place in the food safety process depending of what you need. If you need a quick and cheap verification method for cleaning effectiveness in equipment this is great as we all know, but it could also be used for hand washing verification.. Although I personally like it more for a training tool for proper hand washing..

 

And yes, the target on hands would not be “0” (as it is not for equipment neither), but you need to make a base line, and of course take the sample right after hands have been washed..   

 

For your reference, I borrowed my ATP tested along with a lot of swabs that were close to expire to my 9 yr. old daughter for her school science project. She wanted to know if there was a difference on cleaning hands for 5. 10 and 20 seconds.  She tested a bunch of kids before washing hands, and then after washed for 5, 10 and 20 seconds with the ATP, I helped her with the data she collected and the ATP test results actually showed a clear baseline and direct relationship between time and cleanliness.  Of course there were some “special causes” (e.g. there is always a kid who uses his hands to dry her hands instead of the paper towel as instructed), but after the data was normalized, we got that in average, dirty hands were 10.223 RLU (Relative Light Units), hands washed after 5 seconds read 228, washed for 10 seconds were 109, and for 20 seconds 31.. (With actually some of single samples in “0”).

 

 

 

Dirty

5 Sec

10 Sec

20 Sec

Average RLU

1022.3

228.8

109.1

31.4

 

 

 

So in conclusion, even this was a “pretend” science project, it is clear that ATP can be a good and cheap instant indicator and monitoring procedure for hand washing, when used properly, and again, depending of what you need to achieve.

[Charles.C]

Hi Antores,

 

Thks for the informative post and project data.

 

Right, ATP It does not detect bacteria but Adenosine triphosphate…….

 

I half agree with yr statement. The ATP (test) technique does detect bacteria albeit not to a species level, eg –

 

 atp methodology.pdf   91.26KB   100 downloads

 

For hand hygiene evaluation there seems some differences of opinion between manufacturers –

 

Neogen

Can we use an ATP system at our hospital to test for hand cleanliness?  Answer:  Not recommended.   Why not? Your skin is composed of cells that have ATP. While in theory it might be possible to establish a clean baseline for an individual, the baseline would likely vary between individuals so meaningful comparisons would not be valid. The amount of ATP on your hands is also likely to be effected by other factors like dryness and the amount of time since last washing (whether they’re “dirty” or not). Finally, “clean” hands will typically still contain a lot of ATP with resulting very high RLU scores. An awful lot of potentially problematic microbial ATP can be disguised within even a 5% variation.  

 neogen - using ATP to test hand cleanliness.pdf   383.7KB   92 downloads

 

Hygiena

Some interesting practical data shown using their marketed instrument. In addition to the manufacturer’s comments, the data illustrates (as noted above) the problem of setting  a single standard where different  hands are (apparently?) of considerably different initial cleanliness – even perfect handwashing technique has a limit to how much “dirt” can be removed in one stage.

 hygiena - using-atp-to-monitor-hand-hygiene.pdf   328.18KB   100 downloads

 

Despite earlier reservations about baseline stability, the Hygiena system below apparently enabled a stable zero level although using a rather different pass level, presumably due the situation.

 Improved hand hygiene technique in hospital scenario.pdf   132.09KB   71 downloads

 

Just for context, here is an extended opinion on the meaningful reality of assessing hand hygiene -

 hand hygiene evaluation.pdf   436.04KB   162 downloads

[Tony-C]

Hello Everyone

 

I am editing a testing schedule and on the schedule it states test for Staphylococcus aureus and Coliforms for hand swabs. It also then states test for E.coli only if Coliforms are positive. Is this correct? The problem I have with this statement is that swabs need to be tested within 24 hours of it being sampled. A specific swab can also NOT be re-tested. So how is it possible to test for E.coli if Coliforms are positive? By then the staff member would have washed their hands clean. I was thinking perhaps take Coliforms off the schedule and test only for E.coli instead. The other alternative would be to test for everything.What do you all think?

 

Michelé

 

Hi Michelé,

 

I don't see the need to follow up with E.coli, this is a hand swab not a product. A positive coliform result is an indicator of poor hygiene and the necessary action (re-training or disciplinary) should be taken irrespective of whether there was E.coli present or not.

 

Regards,

 

Tony

 

I don’t know what your operation is, and why it would require testing hands for coliforms and stapah, but it seems like a waste of resources for me, unless is done as validation for a hand washing process, or may be part of your hiring requirements to be sure new employees are staph free?

May be this is a normal procedure in your industry and geographical area, but what is the purpose of that? How long it takes to get results on coliforms, and what the employee does during that time? and if it comes positive.. What is the corrective action? All I see they can do is wash their hands again anyways..

I’m trying to understand why you are not doing ATP testing instead, get result instantly, and if results are out of the stablished range, then re-wash hands immediately (re-train if necessary) and re-test.. The whole process may take just 5 minutes.

Again, Just trying to understand why are you doing that..

 

ATP swabs may detect gross contamination on hands but are not a reliable method for assessing hand hygiene because as previous posters have indicated ATP is released from cells during hand washing/scrubbing.

 

Regards,

 

Tony

[Raj123]

Hai everyone

 

Is there any standards stating area to be covered during swab ? for eg 10 sq.cm or 25 sq.cm. if so how many parallel streaks are required for swabbing as per standards ?

As per indian EIC standard, In workers hand 100 cfu /cm2 is permissible limits. then if we consider petridish area 100mm=60cm2,count will be approximately 60000 total cfu. Is it ok ? please help me to find correct answer.

[UnbakedOlive]

Hi Antores,

 

Thks for the informative post and project data.

 

 

I half agree with yr statement. The ATP (test) technique does detect bacteria albeit not to a species level, eg –

 

atp methodology.pdf

 

For hand hygiene evaluation there seems some differences of opinion between manufacturers –

 

Neogen

Can we use an ATP system at our hospital to test for hand cleanliness?  Answer:  Not recommended.   Why not? Your skin is composed of cells that have ATP. While in theory it might be possible to establish a clean baseline for an individual, the baseline would likely vary between individuals so meaningful comparisons would not be valid. The amount of ATP on your hands is also likely to be effected by other factors like dryness and the amount of time since last washing (whether they’re “dirty” or not). Finally, “clean” hands will typically still contain a lot of ATP with resulting very high RLU scores. An awful lot of potentially problematic microbial ATP can be disguised within even a 5% variation.  

neogen - using ATP to test hand cleanliness.pdf

 

Hygiena

Some interesting practical data shown using their marketed instrument. In addition to the manufacturer’s comments, the data illustrates (as noted above) the problem of setting  a single standard where different  hands are (apparently?) of considerably different initial cleanliness – even perfect handwashing technique has a limit to how much “dirt” can be removed in one stage.

hygiena - using-atp-to-monitor-hand-hygiene.pdf

 

Despite earlier reservations about baseline stability, the Hygiena system below apparently enabled a stable zero level although using a rather different pass level, presumably due the situation.

Improved hand hygiene technique in hospital scenario.pdf

 

Just for context, here is an extended opinion on the meaningful reality of assessing hand hygiene -

hand hygiene evaluation.pdf

 

Hi Charles,

 

I was browsing on google and stumbled upon your post.

 

 

I find the 'hand hygiene evaluation' you shared very interesting.

Can you direct me to the source?

 

Cheers,

Bob

[Charles.C]

Hi Charles,

 

I was browsing on google and stumbled upon your post.

 

 

I find the 'hand hygiene evaluation' you shared very interesting.

Can you direct me to the source?

 

Cheers,

Bob

Hi Bob,

 

My compliments on your searching prowess.

 

Source was "Hygiene in Food Processing: Principles and Practice,  2014"