Slide surface monitoring technology has been developed as a convenient, cost-effective method of monitoring the efficacy of disinfecting agents or cleaning procedures in eliminating microorganisms from surfaces. By inoculating the slide growth medium by direct contact with the surface to be sampled; the need for swabs, transport medium, sophisticated laboratory facilities and technologist time are virtually eliminated. Surface monitoring is desirable, if not required as a part of the health and safety programs, and quality assurance programs of many institutions and services involved in health care and food handling. User requirements are satisfied by a variety of growth media available on our surface slides. The slide contact technique is useful in HACCP (Hazard Analysis Critical Control Point) programs as an alternative to surface contact plates.

The surface monitoring slide is simply an agar coated plastic slide which is attached to the cap of a shatter-proof, optically clear, colorless plastic vial. To sample a surface, remove the cap/slide assembly from the vial. Holding cap in hand, press the surface of the medium (Side A) gently onto the surface to be tested (paddle will flex to right angles with a gentle pushing motion). Select a second site to be sampled, repeat sampling by gently pressing the other side of the slide (Side B) onto the surface to be sampled. Return the cap/slide to the plastic vial, record sampling information on the label provided and place the vial in an incubator at 30o - 33o C . For bacterial contamination, read the results after 24 hr. incubation and record your observations. Microbial growth is evaluated in terms of number of colonies, morphology and other features. Fungal contaminants may take several days to grow. The slide should be retained and observed over a 3 - 5 day period for evidence of fungal contamination.

Solar Biologicals Inc. surface contact monitoring slides are coated on one side with Microbial Content Test Agar to which Lecithin and Polysorbate 80 (tween) are added or DE Neutralizing Agar. This media provide a nutritious environment for microorganisms, while neutralizing the effects of sanitizing agents used in cleaning. The opposite sides are coated with media which help in the presumptive identification of microorganisms and are described below.

Slides coated with Malt Extract Agar, Sabouraud Dextrose Agar or Potato Dextrose Agar are capable of growing fungi. These media are adjusted to the acid side of neutrality (pH approx. 5.5) which not only favors the growth of fungi but suppresses growth of most bacterial species.

Alternatively, the other side of the slide may be coated with MacConkey Agar. This highly selective medium is suitable for the identification, detection and enumeration of coliform organisms. With the inclusion of bile salts and crystal violet, the medium gives improved differentiation between coliforms and non-lactose fermenting organisms while gram-positive cocci are completely inhibited. Sorbitol MacConkey Agar enhances the growth of E. coli 0157.

A further variation entails the addition of Polymyxin B sulfate/CLED (Cystine Lactose Electrolyte-Deficient agar containing Polymyxin B at a level of 28,000 IU / liter) agar to one side of the dipslide. This medium inhibits the growth of most gram-negative bacteria making the medium more selective for gram-positive organisms.

The contact slide technique permits the user to obtain an approximate count of bacterial cells present on the surface tested. The surface area of the slide is 12 square cm. A mathematical correlation may be obtained between the number of colonies growing on the surface of the slide and the area of the surface tested. This may be useful information in the analysis of the effectiveness of cleaning agents and methods. Fungal levels are reported as nil, low, moderate or heavy contamination. Counts are not meaningful as a measure of fungal contamination.