To the Editor:
In a recent CleanRooms magazine article entitled “Examining ways to capture airborne microorganisms,” I noticed that the SMA Microbial Air Sampler was not included nor even mentioned as a possible methodology to test for the presence of viable contaminants in controlled areas. Due to its well acceptance in the pharmaceutical and biotechnology industry for over 15 years, I am surprised that neither the authors nor the editors of CleanRooms did not require or question its exclusion. In addition, the readership of CleanRooms should be aware that this article was published in a very commercialized tone. The SMA`s exclusion, the commercialized tone, and the incorrect identifying of industry standards should warrant correction by the publication. If CleanRooms magazine`s desire is to publish accurate data on comparative products, then consideration should be given to assure technical editing of presentations prior to publication. The article commercialized the subject to benefit the author`s product, inaccurately depicted characteristics of the available units and incorrectly presented details and acceptance of the proposed USP Chapter. Appropriate technical editing would have eliminated these inconsistencies and assured that the readership was accurately and completely informed on the subject.
To complete the list of available microbial air samplers in the industry, the SMA Microbial Air Sampler needs to be discussed. It is over 15 years old and is used by a multitude of pharmaceutical and biotechnology manufacturing operations worldwide. The SMA Microbial Air Sampler provides either multi-location system integration or battery operated portable units that can be moved from site to site. The unique design and multitude of units, assure the ability of the SMA Microbial Air Sampler to conduct full testing for the presence of viable contamination in cleanrooms, laboratories, preparation areas and compressed air lines.
The SMA Microbial Air Sampler is designed to operate from the basic principle of inertial impaction or a single stage cascade impactor theory. This concept is combined with the ability to integrate units that provide either “Facility System Capabilities” or “Battery Operated Portable Capabilities.” This assures that the specific concerns surrounding the accurate monitoring for microbial contaminants are addressed with a variety of sampler options. Unlike other samplers in the marketplace, to accommodate this function the SMA product line is divided into two different system types, either the SMA Atrium and Control Centers or the SMA MicroPortable.
The SMA Atrium and Control Centers
The letters “SMA” stand for the “Sterilizable Microbiological Atrium.” The “Atrium” refers to the sampler itself and is, as it sounds, the only unit in the marketplace that can be completely steam sterilized as it is made of either anodized aluminum or stainless steel. This concept assures that the Atrium located at the point of sample is validated as sterile each and every time. This assures the elimination of possible contamination from the sampler itself that may dually contaminate the manufacturing environment and compromise the integrity of results. Thus, recorded results are only representative of environmental conditions that exist in the tested area. The adapted SMA Compressed Air Sampler assures the efficient testing of possible contaminants in compressed air or gas lines.
The SMA Atriums utilize 100 ¥ 15 ¥ 25 ml fill nutrient media plates. Most manufacturers of nutrient media have incorporated these plates as a standard product. During the unit`s initial validation, capture efficiency studies were foremost in validating the unit for cleanroom use. By introduction of a known number of organisms with an expected populous referencing size, the unit was evaluated on what it captured and what it lost. Testing included the introduction of organisms to the sampler with the exhaust air evaluated through a liquid impinger to delineate loss. During precipitation of the aerosolized organisms to a plenum, there was a loss of what was introduced to the unit as some of the precipitate clung to the plenum walls. This was compensated for by evaluating the total captured plus the total lost in representing the total organisms introduced to the unit. Evaluation of results from the liquid impinger delineated the number of organisms lost. The number lost was then divided by the total sampled to attain the efficiency rating. The SMA Atrium testing resulted in the evaluation that the unit was more or less accurate for varying organism size categories. From a size of 0.65 to 2.0 microns the SMA Atrium was calculated to be 90 percent efficient. From 3.0 to 10.0 microns the unit operated at 82 percent efficiency and from 11.0 to 20.0 microns the unit operated at 73 percent efficiency. The SMA Atrium is available in a variety of orifice top sizes that lend to the accurate evaluation of microbial levels in varying controlled and uncontrolled environments.
During evaluation of microbial air samplers side by side in a non-controlled environment, there are many factors that compromise results. Testing should consider the elimination of as many variables as possible such as temperature, relative humidity, dynamic drag, air currents, accurate evaluation of the testing environment for microbial background levels, sampler contamination, inconsistent result determination, and the use of the same nutrient media by the same vendor that has been QC tested for growth promotion. Elimination of as many variables as is possible prior to conducting testing is advised.
The Atrium requires only a vacuum connection to either a central vacuum or one of the SMA OneTouch Control Centers. The SMA OneTouch Control Centers sample from 1 to 10 locations. They provide calibrated air flow, timing, 0.2-micron filtered exhaust and vacuum in one system. The multi-location capabilities of the Control Centers provide the ability for system integration and the remote location of the Control Centers and vacuum source from the Atrium located within the controlled environment. The SMA Control Centers operate either locally or remotely by what is termed the “OneTouch Command Principle,” a standard feature that enables either a flush-mount wall monitor or point-of-sample module to be hardwired into the processing area. These stainless steel cleanroom monitors or modules allow the remote starting of sampling at the desired location. An electronic signal is conveyed to the control center initiating sampling to the preset time and air flow. The system is immediately reset for the next sample when the control center sampling is completed. Indicator lights within the controlled area signify that testing is being conducted, sampling is complete and that the vacuum source located remotely is in operation. The SMA OneTouch System capabilities further include the transmission of data such as location number, time of sample, date of sample, and volume of sample via computer terminal lines to the OneTouch Command Center Database. The SMA OneTouch Command Center Database is a computer program designed to assure the accurate importation of pertinent monitoring data on a continuous basis. The SMA OneTouch System is the first microbial air sampler to provide computerization capabilities for facility system integration.
For isolators, the SMA OneTouch CC-I Systems include all the features of the normal SMA Control Centers. Special attention rises to the integration of the “ISO-Flow Mechanism.” The ISO-Flow mechanism assures the continuous exit and recirculation of air from the SMA Atriums. Coupled with an integrated 0.2 micron filter, this system eliminates the possible return of exterior environmental air to the interior isolator environment. During the sampling sequence, the air is drawn out through the vacuum lines to the control center. Upon completion the control center timers signal solenoid valves within the control center to switch flow to the isolators` central vacuum system. Thus, the continuous exit of filtered air without concern of back pressure air return. The CC-I Systems are VHPH and steam sterilization resistant.
The SMA MicroPortable
The SMA MicroPortable utilizes the technology of the SMA Atrium with relationship to capture of varying viable contaminants. The SMA MicroPortable is, as it sounds, the portable SMA system. The unit assures an eight-hour continuous operation battery, 316L stainless steel construction, calibrated air flow, varying volume selection and selection of either 1 cfm or 5 cfm flow rates. The SMA MicroPortable is the newest of the SMA products and attains equal capture of a known particulate size of 0.5 microns to 20 microns.
The full circle microbial contaminant capabilities of the SMA Microbial Air Samplers coupled with the support of both the pharmaceutical and biotechnology industry warrant its inclusion in presented comparisons.
Art Vellutato, Jr.
Vice President, Sales & Marketing
Veltek Associates, Inc.