A note on the recovery of micro-organisms from an oil-in-water cream.
The isolation of micro-organisms from the oil-in-water Aqueous Cream BP, has been examined using a variety of solvent systems to disperse the cream prior to membrane filtration or direct inoculation. Pour-plate methods which utilize combinations of either peptone-water (containing 5% w/v polysorbate 80) or nutrient broth (containing 4% w/v Lubrol W) provided the most efficient recovery of Pseudomonas aeruginosa but still allowed less than 20% recovery. White spirit and isopropyl myristate allowed no recovery when used as dispersants. Recoveries of P. aeruginosa varied according to the source of the cream. A combination of 1% w/v polysorbate 80 in 0.1% w/v peptone-water and membrane filtration allowed 63.2% w/v and 67.0% w/v recoveries respectively of Aspergillus niger and Candida albicans from unpreserved aqueous cream, but gave unreproducible results for Escherichia coli and P. aeruginosa. Chlorocresol 0.1% w/v) did not meet the British Pharmacopoeial requirements for efficacy of antimicrobial preservatives when tested against C. albicans using membrane filtration to isolate the micro-organism.
D001234:Aspergillus niger / Q000302:isolation & purification*; D001419:Bacteria / Q000302:isolation & purification*; D002176:Candida albicans / Q000302:isolation & purification*; D003408:Cresols / Q000494:pharmacology; D004340:Drug Contamination; D004926:Escherichia coli / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D009824:Ointments; D011310:Preservatives, Pharmaceutical; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification; D013291:Streptococcus / Q000302:isolation & purification
D003408:Cresols; D009824:Ointments; D011310:Preservatives, Pharmaceutical; C006984:chlorocresol