Biological contamination events in isolators: What lessons can be learned?

Transcription

1 WHITE PAPER SCIENCE DRIVEN BIO-DECONTAMINATION LS001-MKT-008 Rev 1US Biological contamination events in isolators: What lessons can be learned? James Drinkwater, Bioquell UK Process & Compliance Director. Chairman of PHSS Pharmaceutical & Healthcare Sciences Society. Biological contamination in isolators Microbiological deviation and biological contamination events have been observed in pharmaceutical isolators including those used in production, sterility test and pharmacy aseptic services. This paper considers a range of real-life biological contamination event cases studies, reviews the root causes that were identified and looks at what lessons can be learned.

2 Some biological contamination events in pharmaceutical isolators are a result of limited knowledge or understanding of the various process steps involved in: biological contamination control bio-decontamination microbiological deviation management. The following case studies are from real events that illustrate some of these points. They have been anonymized to protect the client s identity but each has a detailed biological contamination event with the route cause that was reported after investigation. There are lessons to be learned in every situation suggesting knowledge, hands-on operation and process management still require improvement. Case 1. Production isolator using hydrogen peroxide vapor gaseous disinfection. Biological contamination event under investigation: Sporadic indications of contamination in a production isolator used for aseptic compounding of sterile medicinal products. The typical environmental monitoring trend for this production isolator regularly bio-decontaminated with hydrogen peroxide vapor was demonstrated to be zero colonity forming unit (cfu) recovery. However, sporadic deviations were observed, typically with one cfu result recorded in environmental monitoring. These microorganisms were identified to be from a human source. With acceptance criteria set at zero cfu (GMP Annex 1), the batches of product produced in the isolator environment that had the biological contamination event were discarded. They were classed as having been produced in a non-compliant environment. After each incidence, an intense investigation took place on the isolator. This also examined the efficacy of the biodecontamination cycle. Here biological indicator challenges verified a 6-log sporicidal reduction. Unfortunately, neither a route cause nor a probable cause could be identified. Without a definitive answer, the production team employed a consultant to review the investigation. The specialist identified that not enough attention was placed on possible biological contamination after sampling. It was felt that secondary contamination of the growth media plate during transfer to the off-site microbiological laboratory was occurring. On closer inspection of one randomly contaminated environmental monitoring settle plate, it was noted all growth was on the edge. This indicated past presence of condensation and possible tracking of biological contamination from the outside of the plate to the agar media. It was noted that before transfer to the lab, each plate was sealed and non-sterile cling film was used to wrap the plates. The procedure to wrap the agar plates in cling film was an extra security step added for transport to a lab at greater distance. It was also found some monitoring plates took a considerable time in transfer before incubation. Overall this process promoted condensation as environmental temperatures changed. It was correct to consider the biological contamination event as significant to the normal trend of results as this could indicate a loss of control. However it was an oversight not to consider the sample transfer as a possible route cause for a false positive. The microbiological lab may confirm this result was not a lab error but samples that are contaminated after leaving the process zone will be reported as positive results. It is always important to complete a thorough investigation to confirm the isolator state of control, but as shown in this case, the study always needs to be wider than just the process environment. Case 2. Sterility test isolator pharmaceutical facility. Biological contamination event under investigation: Finger dab positives from a sterility test isolator with the microorganisms identified from a human source. Product line drug samples were sterility tested in a flexible film sterility test isolator using a batch process. Test material loads and product samples were gassed with hydrogen peroxide vapor together with the sterility test isolator. All load materials were placed on point-of-contact supports for gassing exposure and all sterility testing completed with the isolator closed and not opened until the test was complete. Packaging waste was transferred out via a rapid transfer port container. An independent consultant developed the hydrogen peroxide vapor cycle. This consultant had expertise on one type of vapor generator but virtually none on the type of generator in use on this isolator. However cycle development was completed for a fixed test load and regulatory approval granted. Over time as product samples changed, environmental monitoring results indicated isolator finger dab positives with a human source of the microorganism. There were low-level (1 cfu) and random positives. All critical parameters including the validity of calibration, validity of the decontamination agent and laboratory protocols were checked and found to be compliant. The difference of the load pattern, as a result of change in product samples had never been studied in cycle development. This meant the cycle could not be assured as having the required process efficacy either by gas distribution or distribution of the disinfection agent to target surfaces. Clear rationale and study is always required for processes that include variable load patterns. The changes in load pattern challenged the point-of-contact support features designed for the original fixed validated load. It is highly likely finger dab positive results were from occluded surfaces of packaging in loads. The items were potentially permitted to touch these occluding surfaces and hence immune from the bio-decontamination process.

3 Case 3. Contract sterility test services using a sterility test isolator. Biological contamination event under investigation: Spore contamination was routinely detected in environmental monitoring results of a sterility test isolator. A microbiological lab ran a batch process using a sterility test isolator with uni-directional airflow and combined hydrogen peroxide vapor gassing of test loads and samples. The isolator was opened up only after all sterility tests were completed. Packaging waste was removed by a rapid transfer port bag-out system. Samples arrived from all over the country and often there was no triple or double over-packing to prevent biological contamination entry into the test cleanroom and facility. The contract test company had installed an alcohol bath just in front of the sterility test isolator. This meant product samples could be washed down in the bath before loading in the isolator on point-of-contact supports. As some product samples were not in gas-tight closures, they were not suitable for exposure to hydrogen peroxide vapor bio-decontamination. In these cases, the samples were simply manually disinfected in the alcohol bath and entered the gassed isolator via a rapid transfer port container. Spore contamination was routinely detected in environmental monitoring results of the sterility test isolator. As far as the contract manufacturer was concerned this was a limitation of the hydrogen peroxide bio-decontamination process. The customer was told by the isolator manufacturer to expect from time to time a few unexplained results. This was expected with a process not considered equal to full sterilization e.g. autoclaving. Any bio-decontamination in a hydrogen peroxide vapor decontaminated isolator should be recognized as a significant event. There should be no occasional and expected low-level biological contamination that does not indicate a change in control state. In this case, the use of the alcohol bath was to remove significant amounts of bioburden. This was used to overcome poor contamination control of the sample supply into the cleanroom facilities. Alcohol is not sporicidal hence spores would remain on the top surface of the alcohol and probably coat items entering the isolator rather than remove them. It is unlikely that the hydrogen peroxide cycle would have been studied for efficacy against such a high starting bioburden of highly resistant spores. The manual disinfection transfer would potentially transfer biological contamination onto samples into the gassed isolator and, without a further bio-decontamination step, biological contamination events were likely to occur. Put simply, the process was flawed. There needed to be better control downstream of test samples that left controlled cleanroom areas. The clean state of such samples should have been maintained to prevent contamination in transit to the test lab and the typical GMP process of step removal of packaging layers at barriers should have been used to remove the significant challenge of bio-burden entering the sterility test facility. These would have negated the need for the alcohol bath. Case 4. Pharmacy isolator with only manual cleaning and disinfection process. Biological contamination event under investigation: Random but regular levels of biological contamination above the required GMP Annex 1 levels. Isolators producing pharmacy prescription materials that only use a manual disinfection process (e.g. spray and wipe disinfection) often demonstrate random but regular levels of biological contamination above the required GMP Annex 1 levels i.e. zero cfu. Any manual disinfection process is highly operator dependent. Other process variables can also impact efficacy, e.g. isolator HEPA filtered airflows can dry out surface-applied disinfectants and therefore reduce the contact time required for microbial kill. Pharmacy isolators typically use a closed transfer process, e.g. vial to syringe to IV bag. In this situation, the biological contamination risk is at the aseptic connections. Biological contamination that enters a pharmacy isolator can put products and patients at risk and quality risk management will be required. The challenge here is the variability in the bio-decontamination process and corresponding variability in environmental monitoring results that require investigation. Microbiological deviations require an investigation that is a significant work load for QC and potentially more significant contamination events may be overshadowed by other anomalous results. Biological contamination events can be reduced/eliminated and time consuming (and expensive) deviation investigations can be overcome by use of high-level bio-decontamination processes (such as hydrogen peroxide vapor). It may be possible to retrofit such systems into pre-existing isolators. However, special consideration may be required for material load disinfection in these isolators. This is required to ensure the new biodecontamination process provides assured efficacy and short, workable cycle times for pharmacy aseptic services. Processes that use manual disinfection require significant levels of training, procedural control and monitoring to manage biological contamination risks. Environmental results, such as rate of incidence and the level of growth on media plates, must be regularly reviewed. Products prepared in pharmacy isolators are often for immediate use. This reduces the chance of proliferation of microbial growth to clinically significant levels. But there are areas of the isolator, like glove sleeve connections, that need a deep clean disinfection. These parts may need to be removed for improved cleaning and decontamination access. If not addressed, biological contamination can remain resident in the isolator for some time. By far the greatest risk of biological contamination transfer is on material prescription loads. Here contaminated glove fingers (as a result of handling partially decontaminated materials) can be used in very close proximity to aseptic connections for sterile product transfers. This can lead to the introduction of unwanted biological material into the aseptic areas. A suitable broth transfer at the end of each production batch/ session, conducted within the environmental monitoring programme and not just based on an arbitrary qualification by the operator, may support biological contamination risk management. This tests both operator technique and is closer to a process simulation where risks of biological contamination are real.

4 Case 5. Pharmacy isolator that uses a combination of gassing the isolator empty (with H 2 vapor) and spray and wipe disinfection of materials entering the isolator. Biological contamination event under investigation: Relatively high cfu growth in isolators used for cytotoxic reconstitutions. In this case study, the isolators were used for cytotoxic reconstitutions for single patient prescriptions. They were turbulent flow isolators but configured for routine (empty) gassing with hydrogen peroxide vapor. The isolators were gassed with the inner transfer hatch doors open so the transfer hatches were decontaminated at the same time. The hydrogen peroxide vapor cycle was validated for 6-log sporicidal efficacy with biological indicator challenges. The material load transfers within these isolators were decontaminated by a manual spray and wipe process (as the HPV gassing cycle would have been far too long when using a transfer hatch). In start up, the environmental monitoring results demonstrated cfu recovery from up to 10% of the growth media sample plates. Following more intense training to improve the manual disinfection process, the environmental monitoring (settle and finger dab) results reduced cfu growth to 5% of the sample plates. It was considered if the gassing frequency of the isolator would make any difference to the biological contamination results e.g. typically two weeks between gassing being reduced to a weekly gassing process, but after study it was found this had very little impact. Sterile outer packaging is difficult to bio-decontaminate with a manual disinfection process. Bio-decontamination of material surfaces is a highly variable process and it is difficult to control in order to prevent bio-decontamination. As the pharmacy process is highly manual, with the same gloved hands handling packaging, sterile drug product containers and process transfer devices, then biological contamination risks are present. Gassing the isolators will manage resident biological contamination but the moment partially disinfected loads (as a result of a poor bio-decontamination process) enter the isolator process zone, the cycle of biological contamination risk restarts. It cannot be stressed enough how important the load transfer disinfection process is in the context of biological contamination control in pharmacy isolators. Case 6. Pharmacy isolator using full gassing technology (with H 2 vapour) for the full module isolator and in rapid gassing of materials entering the isolator. Biological contamination event under investigation: Unexpected fungal and spore contamination in isolators within an aseptic services unit. Within an aseptic preparation suite of isolators using hydrogen peroxide gassing disinfection, environmental monitoring indicated a loss of control state with unexpected microbiological growth (fungi and spores) found. The aseptic preparation module included two interconnected turbulent flow isolators with a rapid gassing chamber used for entry of materials to the isolator process zone. The isolator module was typically held for an aseptic hold time (i.e. time between re-gassing) of two weeks with secure entry of materials via rapid gassing and exit via a bag-out heat seal system. In addition to microbiological results, the gas concentration ppm levels were indicating reduced values from the normal trend. However these low values were set against already depressed low values as a result of a poor monitoring location. Overall, it was difficult to interpret the actual impact of the relatively small change in ppm levels. Although it was understood that load presentation in the rapid gassing chamber was critical (e.g. touching and occluded surfaces of loads would not be decontaminated by the gassing cycle), the use of defined point-of-contact supports racking had controlled biological contamination entry into the isolators. It was therefore considered that there were other possible root causes for the detected microbiological contamination. See Table 1. Fault path leading towards bio-contamination event 1. H 2 vapor injection nozzle temperature alarm limits widened outside required monitoring range. Set to low 20 C and High 70 C for all H 2 injection nozzles. 2. Low ppm results in isolator chamber module cycles noted. 3. Insulation on heat traced pipework comes loose together with general degradation 4. Microbiological growth (spores and fungi) detected in isolators environmentally monitoring program. 5. Root cause investigation started into unexpected microbiological contamination 6. The pharmacy QC initiated a process and compliance training session to understand critical control points and possible causes for deviation. Cause or probable cause Service engineer adjusted temperature alarm limits for testing but failed to return to required monitoring limits after service. In effect primary monitoring was removed. Process change but with poor monitoring location it was difficult to judge impact. In effect secondary monitoring was poor and difficult to judge impact. The pipework and associated heat tracing-insulation and nozzles in isolators were not covered in the service contracts and fell in a gap between suppliers. The isolator inlet nozzle temperature dropped to 30 C as a result of insulation degradation and at this temperature hydrogen peroxide will condense on route. The combined removal of primary monitoring together with system degradation led to an undetected change in the control condition leading to sub-lethal decontamination cycles. Pharmacy QC were not aware of the alarm set-points for nozzle outlet vapor temperatures held in the rapid gassing chamber software with access only via the chamber HMI (via password). These values are for system set up and not printed on batch records. Table 1. Summary of the fault path that led to the microbiological contamination event in case 6.

5 Hydrogen peroxide is a condensable vapor. Low delivery temperature in vapour delivery pipework and particularly at injection nozzles (end of delivery line) would mean losses in condensation en route to the target isolator zone. In this system the minimum delivery temperature was 40 C to carry the injected hydrogen peroxide at the defined flow rate with the actual injection temperature reduced to 30 C as a result of a fault. Lower temperatures than that validated for the hydrogen peroxide in the target area would mean micro-condensation levels were insufficient for effective bio-decontamination. This would invalidate the cycle. By having wide alarm limits, the ability to detect deviation was removed leaving the system open to change that could have compromised the cycle efficacy. The degradation of the insulation was not detected by the system and without service, the insulation cover continued to degrade until microbiological results indicated a system failure. Although the low ppm gas concentration values indicated a shift in control, the monitoring values were not useful as the in-process monitoring location was after the HEPA filters in the return gas path (this is where ppm values are typically depressed as result of filter absorption). Relocation of the H 2 gas sensor (moved to direct measurement in the process zone) was completed in correction and preventative action (CAPA) to improve monitoring. CAPA also included the resetting of critical monitoring and alarm points so that primary and secondary monitoring could be reinstated. In summary By increasing the understanding of potential route causes and developing process knowledge, then biological contamination risks can be managed from a process design and operations perspective as a proactive and preventative step. In contrast, unexpected biological contamination requires a response where a formal process of root cause analysis (RCA), microbiological identification (at species level) and correction and preventative action (CAPA) is carried out to avoid reoccurrence. This can be a time consuming process, interfering with production operations and significantly increasing the QA work load (as the costly process of root cause investigation needs implementing and managing). Disclaimer: Bioquell UK Ltd or its affiliates, distributors, agents or licensees (together Bioquell ) recommends that customers ensure that the requisite level of bio-decontamination is achieved using standard biological indicators such as 6-log Geobacillus stearothermophilus spores; and the Bioquell technologies, subject to appropriate cycle development, are designed to be able to provide such levels of bio-deactivation. Bioquell is a registered trade mark of Bioquell UK Ltd. Bioquell Inc (2012). All rights reserved. E: info@bioquell.com W: Bioquell USA T: +1 (215) Bioquell UK T: +44 (0) Bioquell Ireland T: +353 (0) Bioquell Asia Pacific T: Bioquell France T: +33 (0) Bioquell China T: LS001-MKT-008 Rev 1 US