j. Soc. Cosmet. Chem., 35, 253-263 (August 1984) Comparison of the API 20E, Flow, and Minitek systems for the identification of enteric and nonfermentative bacteria isolated from cosmetic raw materials JOHN K. McLAUGHLIN, BARRY D. ZUCKERMAN, SAUL TENENBAUM, and BARBARA A. WOLF, Revlon Research Center, 2121 Route 27, Edison, New Jersey 08818. Received February 1 O, 1984. Presented at the SCC-SIM Microbiological Seminar, New York, December 9, 1981. Synopsis Five commercial identification systems, (API 20E, Flow Enteric-Tek and N/F System, and Minitek for Enterobacteriaceae and Nonfermenters) were compared with conventional methodology in the identification of 94 gram-negative bacteria obtained from cosmetic raw materials and reference sources. The percent agreement between rapid and conventional systems for microbial identifications ranged from 76-88% and 75-79% for enteric and nonfermentative microorganisms, respectively. Regarding individual biochemical tests, the percent agreement between the rapid and conventional systems ranged from 90-96% for enterics and 80-90% for nonfermenters. Greatest variations were found in the accuracy levels of individual bio- chemical tests, with API and Minitek showing the greatest number of inaccurate tests for enterics (2- 54% and 2-51%, respectively) and Flow showing the least (2-15%). Flow also exhibited the smallest incidence of inaccurate reactions for nonfermenters, 2-23%, while API and Minitek showed 2-68% and 4-45%, respectively. Although relatively close levels of identification agreement between rapid and conventional methods were observed, Flow showed the highest percentages of biochemical correlations to conventional systems for the microorganisms studied. With regard to microorganisms isolated from in- dustrial sources, it has been our experience that the Flow systems are most satisfactory for both biochemical accuracy and efficient use of manpower. INTRODUCTION Increasing microbiological surveillance on raw materials used to manufacture cosmetic products has resulted in the need for accurate and rapid microbial identifications. Industrial microbiology laboratories have frequently relied upon the use of conventional identification procedures. These methods, although considered to be accurate, require high levels of expertise due to complex and time consuming inoculation and interpre- tation procedures. The introduction of the multimedia test systems, which claim to provide rapid and accurate identifications utilizing computerized technology, appeared to fulfill this need. The API 20E (API) is frequently accepted as the system of choice for the identification of enteric (ENTB) and nonfermentative (NFB) bacteria, and often is used to replace 253

254 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS conventional methods. Our experiences with API have indicated a relatively low degree of accuracy for NFB isolated from cosmetic sources, often requiring confirmation of API identifications with conventional methods or other identification systems. Studies utilizing clinical and food isolates (1-4) indicate that the Flow (FL) and Minitek (MT) systems are able to identify microorganisms with a high degree of accuracy. However, few studies have been reported evaluating these rapid identification systems using ENTB and NFB isolated from cosmetic sources. Therefore, we undertook to evaluate the FL, MT, and API systems with microorganisms originally isolated from-raw ma- terials used in cosmetic products. Our aim was to select an identification system or systems which could correlate with conventional media and provide accurate and rapid identifications of both ENTB and NFB. MATERIALS AND METHODS CULTURES The 94 microorganisms tested (41 ENTB and 53 NFB) included 79 commonly en- countered raw material isolates and 15 stock reference cultures obtained from the American Type Culture Collection, Flow Laboratories, New York City Department of Health, and Roche Diagnostics. The microorganisms, maintained on Trypticase soy agar (BBL, Cockeysville, MD) slants at 4øC, were checked for purity on blood (BBL) agar plates. One colony from each plate was transferred to 10 ml of Trypticase soy broth (BBL), and incubated at 25øC for 18 and 48 hr for ENTB and NFB respectively. One ml from each broth was pipetted onto a Trypticase soy agar plate and spread over the surface of the agar to produce a bacterial lawn. The plates were incubated at 35øC for 18 h, and the resulting microbial growth was used to inoculate all conventional media and test systems. TEST SYSTEMS (1) API 20E (Analytab Products, Inc., Plainview, N.Y.). Previous experiences in our hands using API have often resulted in inconsistent and variable test reactions. These problems were alleviated to some degree by increasing the recommended inoculum size to approximately a No. 5 MacFarland standard. The inoculum was then added to each strip according to the manufacturer's instructions. ENTB identifications were com- pleted at 24 h NFB identifications were checked at 24 h, reincubated, and completed at 48 h. Microorganisms were identified by accepting the first choice of the API Profile Recognition System. (2) Flow Enteric-Tek and N/F System (Flow Laboratories, McLean, Va. ). The Enteric-Tek system provides for the determination of 14 different biochemical parameters by uti- lizing a wheel of solid media. The systems were inoculated and incubated according to the manufacturer's instructions. Microorganisms were identified by accepting the first choice of the Flow Enteric-Tek System computer code book. The N/F System consists of the two tube N/F-Screen, and the Uni-N/F-Tek plate. The N/F-Screen, composed of the GNF and 42P tubes, contains five tests utilized for the identification of fluorescent pseudomonads. The Uni-N/F-Tek plate is a multicham- bered wheel designed for the determination of 12 different biochemical parameters.