Editor’s Note: The following excerpt is republished from: Saghee, M.R., Sandle, T. and Tidswell, E.C. (Eds.) (2010): Microbiology and Sterility Assurance in Pharmaceuticals and Medical Devices, New Delhi: Business Horizons. Further circulation is prohibited. The book may be purchased at www.businesshorizons.com.
For another chapter from the book, read The New Microbiological Technology Wave.
Within microbiology, a shift is taking place from simple laboratory studies toward greater use of risk assessment and management . Sometimes these approaches form part of a drug company's total quality system, sometimes they exist as standalone techniques. The most important guidelines for pharmaceutical microbiology are described in ICH Q9, including the tools of FMEA (Failure Mode and Effects Analysis); FTA (Fault Tree Analysis); and HACCP (Hazard Analysis Critical Control Points).
The two most commonly used within microbiology are HACCP (which originated in the food industry) and FMEA (which was developed for the engineering industry). This article explores these two approaches, first with a description of HACCP, followed by a description and case study of FMEA in sterility testing.
HACCP: Risk Based Approach in Environmental Monitoring
Hazard Analysis and Critical Control Point (HACCP) is a risk assessment approach that addresses physical, chemical, and biological hazards . HACCP is designed so that key actions, known as Critical Control Points (CCPs) can be taken to reduce or eliminate the risk of the hazards being realized. HACCP involves focusing on where the control points in a process are. Once these are established critical limits are set. The critical limits are then monitored and the process is verified as being in control (or not) . There are different variants of HACCP. The “Lifecycle Approach” is similar to that contained in the FDA “Pharmaceutical cGMPs for the 21st Century: A Risk-Based Approach” .
There are two key components of HACCP:
• Hazard Analysis: Determining what microbiological, physical, or chemical risks are associated with a process.
• Critical Control Point: A point, step, or procedure at which control can be applied.
In general HACCP involves the following:
1) Conducting a hazard analysis. This involves listing all potential hazards associated with each step, conduct a hazard analysis, and consider any measures to control identified hazards. For this process flows are useful. For example, see Figure 1.
2) Determining the Critical Control Points (CCPs).
3) Establishing critical limit(s).
4) Establishing a system to monitor control of the CCP.
5) Establishing the corrective action to be taken when monitoring indicates that a particular CCP is not under control.
6) Establishing procedures for verification to confirm that the HACCP system is working effectively.
7) Establishing documentation and record keeping.
The general methodologies of HACCP are also similar to the principles used in qualification and validation, and the critical control points, are often the same as critical process parameters. This allows for several synergies with other aspects of pharmaceutical quality systems.
There are, nonetheless, some limitations with HACCP. It often has to be combined with other risk assessment tools, like FMEA, in order to allow risks to be prioritized and quantified.
HACCP is also less useful for complex processes and it is less useful if the process is not well known.
FMEA: Risk Based Approach in Sterility Testing
A failure modes and effects analysis (FMEA) examines potential failure modes within a system for classification by severity or determination of the effect of failures on the system. Failure modes are any errors or defects in a process, design, or equipment. Such modes can be potential or actual.
Effects analysis refers to studying the consequences of those failures. FMEA looks at the risk of failure at each process step by evaluating the potential failure modes for the process. It then proceeds to evaluate and document the impact of the failure upon product quality or the next stage in the process. Once the process has been mapped, the emphasis is on eliminating, reducing or controlling performance failures through the use of risk reduction techniques.
Although FMEA can be a powerful tool, it is better applied to equipment, where complex items can be broken down to their key components or operational steps, rather than to process manufacture (where HACCP arguably has the advantage in spotting potential microbiological risks). It also relies upon a detailed process understanding; if the process is not well understood then key steps can be easily missed. Some organisations have attempted to combine both HACCP and FMEA together to overcome the disadvantages with both models.
An example of the application of FMEA is outlined in the case study below.
FMEA was applied to assess risk in a barrier isolator system  used for sterility testing. The following steps were taken:
a) Setting the scope;
b) Defining the problem;
c) Setting scales for factors of severity, occurrence and detection (see below);
d) Process mapping;
e) Defining failure modes;
f) Listing the potential effects of each failure mode;
g) Assigning severity ratings to each process step;
h) Listing potential causes of each failure mode;
i) Assigning and occurrence rating for each failure mode;
j) Examining current controls;
k) Examining mechanisms for detection;
l) Calculating the risk;
m) Examining outcomes and proposing actions to minimize risks.
Where the number of risk is very high, the ICH Q9 guideline proposes the use of a risk filter.
Sterility Testing Isolator: The Case Study
The definition of an Isolator is a device :
a) Provided with microbial retentive filtered air (and which does not exchange any other air with the surrounding environment)
b) Has a decontamination cycle (for the Isolator itself and for material entering)
c) Has a means for material transfer and / or connection to another Isolator
d) No human part directly enters the Isolator
All Isolators are at risk from contamination . Although Isolators are superior in many ways to clean rooms, the approach of regulators, such as the FDA, is: “Barrier Isolators cannot prevent contamination caused by GMP deficiencies such as poor aseptic procedures and inadequate training of…operators.” 
The main risks which different Isolators (those used for both sterility testing and for aseptic filling) are susceptible include :
• Gloves / operator manipulations;
• Other airborne contamination;
• Transfer of material into and out of the Isolator;
• The Isolator room;
• Decontamination cycle;
• Cleaning / environmental monitoring issues.
The Isolator system is used for the sole purpose of performing final product sterility testing on a range of plasma derived parenteral products according to Ph. Eur. 2.6.1 or USP <71>. The methods used are membrane filtration and direct inoculation. A variety of environmental monitoring methods are performed during and after testing: air-samples (passive settle plates and an active volumetric air-sample); finger plates; contact plates and swabs. A spray bottle of a sporicidal disinfectant remains in the Isolator for spillages and for a post-test clean down.
Monthly monitoring is performed in the Isolator room. A number of daily, weekly and six-monthly physical tests are performed on the Isolator system using pressure charts; cleaning and formal classification as a Grade A clean zone (to ISO 14644-1).
A score from 1 to 5 (most severe) was assigned to each of the following categories describing risk.
i) Severity is the consequence of a failure, should it occur;
ii) Occurrence is the likelihood of the failure happening (based on past experience);
iii) Detection is based on the monitoring systems in place and on how likely a failure can be detected.
The following questions were asked of every main part of the isolator system:
i) What is the function of the equipment? How are its performance requirements?
ii) How can it fail to fulfill these functions?
iii) What can cause each failure?
iv) What happens when each failure occurs?
v) How much does each failure matter? What are its consequences?
vi) What can be done to predict or prevent each failure?
vii) What should be done if a suitable proactive task cannot be found?
The scoring system adopted was: a scale from 1 to 5. It followed that the likelihood of high severity would be rated 5; high occurrence rated 5; but a good detection system would be rated 1. The scoring system was based on the Table 1.
Using these criteria a final FMEA score or “risk priority number” is produced:
The total of 125 is derived from: severity score x occurrence score x detect score, or:
5 x 5 x 5 = 125
Depending upon the score produced it can be decided whether further action is needed. There is no published guidance on what the score that dictates some form of action should be. In this study the company adopted a score of 27 as the cut-off value where action was required. This was based on 27 being the score derived when the mid-score is applied to all three categories [i.e. the numerical value ‘3’ from severity (3) x occurrence (3) x detect (3)] and the supposition that if the mid-rating (or a higher number) was scored for all three categories then as a minimum the system should be examined in greater detail.
The FMEA Exercise
To conduct the exercise used the defined scheme on the Isolator system, the Isolator set-up was broken down into a number of critical areas and each area was subsequently assessed. Several of these steps are examined below.
Examination: The Isolator Room
Description of critical area: The Isolator is situated in an unclassified room. There is not requirement to place a sterility testing Isolator in a classified room.
FMEA score: 3 x 1 x 1 = 3
Risk Evaluation: There is no problem considered from the room environment. Entry to the room is controlled; the sanitization cycle has been challenged with a level of microorganisms far greater than would ever be found in the environment (spores of Geobacillus stearothermophilus); all items entering the Isolator are sanitized (using a chlorine dioxide based sporicidal disinfectant) and the Isolator itself is an effective positive pressure barrier to the outside (at >15 Pascal). As detailed earlier, environmental monitoring is performed inside the Isolator during testing . This monitoring, which has an action level of 1 cfu, is designed to detect any potential contamination inside the Isolator environment.
Examination: Potential of Sanitization Cycle Failure
FMEA score: 4 x 1 x 1 = 4
Risk Evaluation: The severity of an ineffective sanitization cycle is a potential sterility test failure. However the sterilizer parameters are checked for every transfer and main Isolator cycle and post-sanitization environmental monitoring is performed on the main Isolator. This has a long history of producing no growth of viable microorganisms.
The Isolators are loaded with a set amount of equipment and consumables. This is described in authorized procedures and the maximum load has been determined through BI studies. One potential area of weakness for the sanitization of the main Isolator are valves for the removal of waste during the membrane filtration sterility test. These are autoclaved prior to each sanitization and during the first hour of the cycle they are opened both inside and outside to allow the sanitization agent to penetrate. A further preventative measure is taken post-sterility testing where the valve which has been used is rinsed through with disinfectant.
Examination: Frequency of Isolator Sanitizations
FMEA score: 4 x 2 x 1 = 8
Risk Evaluation: Each transfer isolator was sanitized, each run using a validated cycle and the Sanitization physical parameters were checked each run (evaporation rate and pressure chart recorder). The main isolator is sanitized every three months (this has been set by monitoring trends in biocontamination over time). Environmental monitoring is performed during each sterility test and examined monthly for trends. Testing showed that, if contamination occurred in the main isolator it did not recur when repeat monitoring is performed. It is reasoned that this is because the level of post-test disinfection is sufficient; that the air-changes in the isolator are such that most contamination will be removed every hour. Furthermore, the main isolator was continuously monitored to show that it remained at positive pressure to the outside. Every six months a range of physical tests were performed: pressure decay, HEPA filter integrity and particle classification.
Examination: Pressure Leaks to Gloves
FMEA score: 4 x 2 x 3 = 24
Risk Evaluation: This FMEA has been given an occurrence of 2 because weekly checks on the gloves do show, on occasions, holes in gloves. A detection of 3 has been given due to reasons outlined below.
The weakest spot on the Isolator is considered to be the glove ports  therefore the gloves have been subject to a separate FMEA. Although these are tested after each test using finger plates and are visually inspected by the testing technician pre-test and weekly, such visual checks are unable to detect pin-pricks leading to slow leakage. Pressure monitoring would show a significant leak from torn gloves but is not subtle enough to detect tiny holes . In order to improve detection the organization undertook to purchase a glove-leak tester. This reduced the FMEA score by improving the detection rate from 3 to 1.
The probability of contamination is further reduced by the use of aseptic technique by the testing technician at all times. Tests are performed to the same level of aseptic technique that would be provided to performing a sterility test in a clean room. Furthermore all technicians are trained in aseptic technique prior to testing final product for batch release. In addition technicians wear a pair of sterile gloves underneath the Isolator gloves and procedures are in place for an aseptic change of gloves. Spare gloves are held in the Isolator for this purpose.
Despite the pre-glove leak testing system FMEA rating of 24—as a possible risk—the exceedingly favorable history of environmental monitoring gives assurance that there is little contamination in the Isolator and no adverse trends. Therefore the gloves are a potential weak spot but this has not been observed in practice. A further weakness is associated with the glove change procedure, which could also be explored as an area for improvement.
Other leaks associated with the Isolator also pose a risk and could be similarly examined through FMEA.
Summary of Other FMEA Exercises
Several other exercises were conducted for this case study, including those for:
• Compromise of Isolator Integrity
• Connection of Transfer Isolator to Main Isolator and Transfer-in / out of Material
• Incomplete Transfer Isolator Sanitization
• Failure of a Daily, Weekly or Six-monthly Physical Parameter - HEPA filters / Pressure Leaks to Canopy
In outlining risk management the chapter has examined some of the risk assessment tools that can be proactively or reactively employed by microbiologists to examine contamination risks. The tools explored in the case studies: FMEA and HACCP are two of the most common. They are not without their limitations and indeed there is no single risk assessment approach applicable to every situation. At times more than one tool will need to be applied and the tools themselves will need to be adapted in order to be appropriate for a given situation. Nevertheless the application of risk assessment is increasingly a key part of pharmaceutical microbiology and the microbiologist is increasingly called upon to use risk assessment as part of contamination control.
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