Settle plates

Grade Air Sample (cfu/m ) Settle Plate, Diameter 90 mm (cfu/4 h) Contact Plate, Diameter 55 mm (cfu/plate) Personnel Glove Print, 5 fingers (cfu/glove)... 

Classification Air, cfuVm Settle plates, cfuV4 hr Surface samples, cfuV5 mm-dia plate... 

Settling plate, M air T air sampler, or slit sampling sampler are used for class 100, level I. Use operating procedure per plant SOP. RCS + (Biotest Hycon) air sampler is used for other classes. A specified sampler shall be used only for class 100 areas. 

Air microbial monitoring should be performed in and around areas of high operator activity. It is not unusual to see settle plates and air sample locations well away from such areas. A typical example is where settle plates are located well to the rear of the filling machine where there is little or no operator activity. The same may be true for air sampling. It is important, therefore, to observe operator activity over a period of time and ensure that the monitoring sites are located so as to monitor operator activity. 

Notes S = settled plate R = RCS + air sampler M = M air T air sampler. The sampling frequency and number of sampling positions can be decreased or increased according to the trend... 

Environmental control monitoring SOP No. All result of active air sampling settle plates RODAC plates, swabs and operator s gloved hand plates within the acceptance limit... 

Settling plates. This method is still widely used as a simple and inexpensive way to quantitatively assess the environments over prolonged exposure times. The exposure of open agar-filled petri dishes or settling plates are not to be used for quantitative estimations of the microbial contamination levels of critical environments. 

The use of settle plates is common practice for monitoring of the microbiological quality of air inside production units. These must then be placed as close a possible to critical parts of the production process in order to show the real microbiological burden to the product. 

Air Sampling The relative cleanliness of air in the most critical environment is assessed using passive sampling systems such as settle plates or estimated volumetri-cally using active air samplers. Active air samplers should be designed to be isokinetic in operation to avoid disruptions to unidirectional airflow. Considerable variability has been reported among the several sampling methods employed for... 

QO-mm-diameter settling plate. These are average values and individual plates may have <4h of exposure. 55-mm contact plates. 

Passive sampling by collecting spores that settle onto a surface (settle plate, or gravity plate) has two critical flaws. Unless precautions are taken to assure perfectly still air over the surface, the volume of air that is sampled cannot be determined and the method is thus nonvolumetric. Volumetric sampling is essential if a concentration of spores is to be determined, which is crucial for rigorously comparing results from different samples. More importantly, passive... 

The gravity settle plate, which provides passive measurement of microorganisms likely to deposit by sedimentation at critical and controlled sites within a given period, and... 

The gravity settle plate measures microorganisms settling from the air onto a known surface area in a known time. Settle plates may be positioned within the critical area at indicator sites where the product may become exposed to airborne contamination, and in controlled areas at locations identified as likely sources or areas of fallout aerobiologic contamination. 

Settle plates cannot be used for quantitative measurement of airborne microorganisms because the... 

Sayer, W.J. MacKnight, N.M. Wilson, H.W. Hospital airborne bacteria as estimated by the andersen sampler versus the gravity settling plate. Am. J. Clin. Path. 1972, 58, 558-562. 

The levels of microbial contamination in the manufacturing areas (Chapter 21) are monitored on a regular basis to confirm that the numbers do not exceed specified limits. The concentrations of bacteria and of yeasts/moulds in the atmosphere may be determined either by use of settle plates (Petri dishes of suitable media exposed for fixed periods, on which the colonies are counted after incubation) or by use of air samplers which cause a known volume of air to be passed over an agar surface. Similarly, the contamination on surfaces, including... 

The efficacy of the filters through which the air is passed should be monitored at predetermined intervals. Air quality may be monitored by volumetric air sampler or settle plate. Table 21.2 describes the maximum concentrations of non-viable particles and viable airborne microorganisms permitted in the four grades of air. 

Aseptic manipulations must be carried out in the grade A air of a laminar flow cabinet. Speed, accuracy and economy of movement are essential features of good aseptic technique. It is therefore essential that workers are well trained and motivated and familiar with the task in hand. Observation and microbiological monitoring of the operator and of the environment are very important. Air quality is measured using settle plates or slit samplers, work surfaces by taking swabs or by use of contact plates (Chapter 20). 

The final method of air sampling is a passive one. This is the settle plate or fallout plate. Quite simply this is an agar plate left open and exposed for a specified period of time. Arguably this is as much a method of quantifying surface contamination as one of measuring air-bome contamination. As with many apparently simple methods, the settle plate represents a significantly complex equilibrium and results should be interpreted with great care. 

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