Recovery and Detection of Microbial Contaminants in Some Non-Sterile Pharmaceutical Products

Background: Microbial contamination of pharmaceutical preparations is a common problem which has been reported for several non-sterile medicaments. The presence of microbial contaminants was not only found to cause physicochemical changes that led to the spoilage of numerous products but was also proved to be a potential health hazard to the consumer. Nonsterile preparations, although not required by most pharmacopoeias to be sterile, are, none the less, required to pass microbial bioburden tests and tests for the absence of certain specified indicator pathogens (Escherichia coli, Salmonella spp., Pseudomonns aeruginosa, Staphylococcus aureus and Candida albicans). Therefore the objective of this study was to test the conditions and challenges for microbial contaminants recovery and detection of specified indicator pathogens in some nonsterile pharmaceutical preparations available in the Egyptian market.


Methods and findings: A total of 280 nonsterile pharmaceutical preparations, obtained either from different pharmaceutical companies or purchased randomly from various retail pharmacies in Egypt, were tested. These samples, which comprised 165 preparations for oral use and 115 preparations for topical use, were subjected to microbial limit testing which included microbial enumeration tests (total viable aerobic count) using the spread plate technique and tests for specified microbial contaminants using standard conventional techniques. Attempts were also made to identify other contaminants. Sample preparation was conducted using methods that have been shown to be suitable for the type of product to be tested and methods applied for microbial recovery were verified for the recovery process (method suitability verification). Sample preparations were sometimes modified as needed based on the results obtained from the method suitability testing and any antimicrobial property present in the product was removed or neutralized before routine testing was conducted. According to the results, microbial contaminants could be recovered from 24.7 % of the tested products. Microbial load varied among the pharmaceutical preparations with oral preparations showing a higher incidence of contamination (33.75%) in comparison to the topical preparations (19.1%).The level of fungal contamination was less than that of bacteria (11.3% and 20% respectively). For bacterial counts, over 95% of the items tested contained fewer than 2 X 10² CFU/ml and only 0.73% contained more than 2 X 10³ CFU/ml. Six products (3 syrups, 2 tablets and 1 cream) were found to exceed the USP specified limits. For fungal counts, about 95% of the items tested contained fewer than 10¹ CFU/ml whilst only 1.8% contained more than 2 X 10 CFU/ml. Three oral preparations (syrups) exceeded the USP specified limits. Regarding the isolates, a total of 60 bacterial and 31 fungal isolates were recovered. Of these isolates, 8 were USP indicator pathogens (15%); five S. aureus isolates (5.5%) were recovered from a cream, a gel, an ointment, a tablet and a syrup; one Pseudomonas aeruginosa isolate (1.1%) was recovered from a capsule; one E .coli isolate (1.1%) and one Candida albicans isolate (1.1%) were recovered from syrups. The incidence of contamination varied considerably but in all cases Gram positive bacilli (sporulating species) accounted for the majority of isolates (30.8%). Also a significant number of the microorganisms isolated from the samples were normal human flora. In case of dosage forms contaminated with fungi, molds constituted the majority of contaminated dosage forms compared to yeast contaminated products.


Conclusion: Testing conditions and challenges could be overcome for recovery and detection of microbial contaminants in collected non sterile pharmaceutical preparations. The microbiological quality of the examined products was, in general, adequate with the exception of few cases. Producers should pay more attention to manufacturing practices and adhere to guidelines given by relevant government authorities. Several measures, including equipment automation, monitoring programs and post-marketing surveillance may be imposed to further reduce the level of microbial contamination of non-sterile pharmaceutical products.


Keywords: Microbial contaminants, recovery and detection, indicator pathogens, microbial limit tests, non-sterile pharmaceuticals






via Archives of Clinical Microbiology http://imedpub.com/ojs/index.php/acmicrob/article/view/720

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