Swab testing

Reassess risk, if neeessary by environmental monitoring, swab tests. 

Notes STOP = swab test on premises, measures antibiotic residues in the kidney FAST = fast antimicrobial screen test, measures antibiotic and sulfonamide residue in kidney and liver SOS = sulfa-on-site, measures for sulfonamide residues. 

FSIS has developed a series of overnight, inexpensive, easy to perform swab bioassay tests for screening tissues, body fluids, or feed extracts for antibiotic residues. The swab tests are used on the farm, in the slaughter plant, or in the laboratory for their designated purpose. Swab test results indicate whether antimicrobial activity is present in the sample at or above allowable levels or absent. Further testing with more sophisticated tests is required to identify and quantify the antibiotics producing the antimicrobial activity. These are usually done in a laboratory as required. 

Basically, all swab tests are performed in the same manner. 

Handbook No. 601, How to Perform the Live Animal Swab Test for Antibiotic Residues, United States Department of Agriculture, Food Safety and Inspection Service, Washington, DC (1984). 

For very rapid on-farm screening of antibiotic residues in animal tissues, the swab test on premises (STOP) has been widely employed (86). This test involves inserting a cotton swab directly into meat tissues, allowing it to absorb tissue fluids. The swab is the removed and placed on a test plate to be incubated with Bacillus subtilis ATCC 6633 spores at 29 C overnight for evidence of inhibition around the swab. 

The calf antibiotic and sulfa test (CAST), the fast antimicrobial screen test (FAST), and the swab test on premises (STOP) are all bacterial inhibition tests developed at the US Department of Agriculture Food Safety and Inspection Services to screen kidneys for antimicrobial drug residues at slaughter (97-101). For CAST and FAST, an incision is made with a knife, whereas for STOP the tissue is macerated with the shaft of the swab. For all three tests, cotton swabs are inserted into kidney tissue to soak up fluids. Swabs are then incubated on inoculated medium with a disc containing an antibiotic standard used to monitor the viability of the organism and its growth inhibition. 

Isolators should have sufficient service port penetrations to allow as much equipment to be placed outside of the isolator as possible. Traditionally control boxes, chillers, keypads, and printers were placed as close to the analytical instrumentation being used as possible. The amount of equipment in direct contact with the samples should be minimized. If equipment needs to be placed in the isolators, the only way to remove that equipment later is to prove that the equipment has been cleaned to acceptable levels by swab testing. Based on experience, this cleaning is difficult to accomplish and in many cases the equipment needs to be considered contaminated and discarded if there is a need to remove it from the isolators. 

Cleaning validation is different in the pilot plant environment than in manufacturing.Again, the lack of process repetition often creates the need to verify that equipment is clean before and/or after the manufacture of batches used in clinical studies on a per batch basis. This can be accomplished by swab testing critical product contact surfaces before and/ or after equipment use to ensure that residual drug is absent or at an acceptably low level. Cleaning... 

There are three basic methods which have been employed for evaluation of microbiological content on surfaces. These include ROD AC (Replicate Organism Detection and Counting) plates, swab testing, and agar overlay or rinse techniques. RODAC plates are the most commonly used of the surface monitoring methods. However, they are not suitable for irregular surfaces, in which case swab techniques are used. 

Other tests based on the use of swabs and microbial inhibition assays were developed at the US Department of Agriculture and Food Safety and are widely used in the United States of America and Canada primarily by meat inspection agencies, including the swab test on premises (STOP), calf antibiotic screen test (CAST), and the fast antibiotic screen test (FAST)." 45 -j g STOP assay employs Bacillus subtilis, and the CAST and FAST assays use Bacillus megaterium. However, these tests will not be discussed further in the context of commercially available assays. 

The tape-stripping method initially described by Rockl et al. [19,20] appears to be a valuable and versatile tool for providing information on the distribution of bacteria in and on the skin [19-21], The tape method has been used as a reliable inexpensive diagnostic tool for quantitative determination of, for example, Pityro-sporum yeast [22], Candida spp. [23], Enterobius spp. [24], and Trichophyton spp. [25], The tape method was found to be more sensitive than swab testing, skin scraping, and direct impression techniques for the determination of quantitative and distribution data of Malassezia spp. on canine skin [26],... 

The USDA/FSIS have a number of rapid tests for determining the presence of antimicrobial substances in carcasses or in live animals. The swab test on premises and the live animal swab test are developed for kidney (or liver) and urine samples, respectively, using an inhibition agar plate assay. The sulfa on site test is used on farm or at slaughter plant to screen samples of serum, urine, or feed for sulfadimidine residues. The test is based on TLC and uses well-defined ratios between concentrations of sulfadimidine in serum or urine and in edible tissues... 

Almost ubiquitously, ATP tests are employed to check plant hygiene. This includes both swab tests of vessels and pipework and liquid tests of CIP final rinse water. Typical sample locations and types are shown in Table 13.7. 

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