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Forty primary clinical isolates and 50 stock cultures of corynebacteria and coryneform bacteria were tested with the Minitek system (BBL Microbiology Systems, Cockeysville, Md.). The Minitek correctly identified all of these organisms, including JK group isolates, within 12 to 18 h of incubation. The method does not require serum supplements for testing carbohydrate utilization by the bacteria. The Minitek system is an extremely simple and rapid way to identify the JK group, as well as many other corynebacteria, by established identification schemata for these bacteria. Diphtheroids are generally considered normal flora in the presence of other commensal bacteria from most body sites, but there are occasions when their presence in a specimen may be considered clinically significant. Accordingly, diphtheroids have been reported in association with a variety of diseases and from many clinical sites (3, 13, 14, 17). Corynebacteria from infected skin, soft tissues, lymph nodes, and blood or body fluids should be identified when they are derived from immunocompromised hosts (17). The need for identification of group JK corynebacteria from patients having clinical evidence of infection is now well established (23, 28). These diphtheroid or diphtheroidlike bacteria were designated group JK by the Special Bacteriology Section of the Centers for Disease Control, Atlanta, Ga. (21). An important feature of the JK group is its resistance to almost all presently available antibiotics (7, 9, 21, 27). It may be that the multiresistant isolates are mutants of susceptible resident skin flora that multiply under the selective responses of antibiotic therapy (17, 24). Septicemia (4, 21) caused by this group of bacteria was shown to occur in patients who have predisposing illnesses, such as neoplasms (7, 10, 19, 21, 23), ventricular shunts, or prosthetic valves (5, 10, 18, 25). JK group isolates have been isolated from a patient with an epicardial pacemaker (8). The JK group have been associated with community-acquired (4) and hospital-acquired (20, 21) infections. Corynebacteria are most often characterized entirely by their gram stain morphology and respective growth characteristics (3). Many of the diphtheroids are relatively inactive biochemically and thus have often been difficult to characterize. A few methods have been recently proposed to differentiate the corynebacteria (1, 3, 12, 15, 21, 26). The present investigation concerns the evaluation of the Minitek (BBL Microbiology Systems, Cockeysville, Md.) identification system as a rapid and uncomplicated way to identify the JK group of coryneforms as well as many other clinically important diphtheroids.

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The grouping of beta-hemolytic streptococcal isolates by a new direct-plate procedure employing Phadebact Streptococcus Test reagents was compared with the results obtained with the 4- and 24-h Phadebact grouping procedure and with the Lancefield grouping obtained with a capillary precipitin test. The new procedure employed a modification of the Phadebact procedure that permitted the grouping of streptococci on glass slides with a minimum of five primary isolated colonies. When only five to eight colonies were available for direct testing with each Phadebact reagent, coagglutination was better manifested when the colonies were disaggregated on a glass slide in a loopful of Tween 80 solution. Further enhancement of the coagglutination reaction was effected when the respective Phadebact reagents were employed in relatively small volumes. The direct-plate procedure permitted the correct identification of 127 out of 129 betahemolytic isolates. The 4-h method correctly identified 192 of the 200 streptococci tested. All of the 200 isolates tested by the 24-h procedure and the Lancefield grouping were correctly identified. The direct-plate Phadebact procedure affords the clinical microbiologist a rapid and reliable means of identifying groups A, B, C, and G beta-hemolytic streptococci. When sufficient numbers of primary colonies are not available for the direct procedure, the 4- or 24-h procedures may be employed.