Rapid biochemical tests for the identification of groups A, B, C, F, and G streptococci from throat cultures

Phosphorylcholine esterase is critical for Dolichos biflorus and Helix pomatia agglutinin binding to pneumococcal teichoic acid

Streptococcus pneumoniae (the pneumococcus) has wall teichoic acid (WTA) and lipoteichoic acid (LTA) expressing the Forssman antigen (FA). Two lectins, Dolichos biflorus agglutinin (DBA) and Helix pomatia agglutinin (HPA), are known to bind FA. To determine the molecular structure targeted by these two lectins, different pneumococcal strains were studied for DBA/HPA binding with flow cytometry and fluorescence microscopy. Genetic experiments were used to further examine the lectins' molecular target. Twelve strains were positive for DBA binding, whereas three were negative. Super-resolution microscopy showed that DBA stained only the subcapsular area of pneumococci. The three DBA nonbinders showed no phosphorylcholine esterase (Pce) activity in vitro, whereas 10 DBA binders displayed Pce activity (the remaining two strains were DBA binders with no Pce activity in vitro). The pcegene sequence for 10 representative strains revealed two functional pce alleles, the previously recognized "allele A" and a newly discovered "allele B" (with 12 additional nucleotides). Isolates with allele B showed no Pce activity in vitro but did bind to DBA, indicating allele B Pce is functional in vivo. Genetic transfer experiments confirmed that either allele is sufficient (and necessary) for DBA binding. The three DBA nonbinders had various mutations that affected Pce function. Observations with HPA were identical to those with DBA. We show that DBA and HPA bind only to the WTA/LTA of pneumococcal isolates with a functional Pce enzyme. A newly discovered Pce variant (allele B) is functional in vivo but nonfunctional when assayed in vitro.

Detection of enzyme activities and their relation to serotypes of bovine and human group B streptococci

Enzymatic properties of group B streptococci (GBS) serotypes from bovine milk and human routine vaginal specimens were investigated. Out of the 56 human and 66 bovine GBS, 35 and 30 could be classified serologically by a co-agglutination test with type-specific antisera, respectively. Hyaluronidase (HYAL), streptokinase (SK) and protease activities were detected using culture media. HYAL activity was observed mostly in typable human GBS, and serotypes Ia, Ic and II comprised 77.3% of the typable strains producing HYAL. Bovine GBS serotypes II, III and VII comprised 87.5% of typable bovine strains exhibiting HYAL activity. SK activity was detected only in three human GBS. Human GBS serotypes Ia, Ic, II, III, VII and almost all typable bovine GBS strains showed protease activity. β-D-glucosidase activity was frequently observed in human GBS, whereas N-acetyl-β-D-glucosaminidase activity was mostly detected in non-typable GBS from humans. These results indicate that different GBS serotypes could vary in their virulence properties, and bovine and human GBS isolates could not be differentiated by their enzyme activities. Use of the culture media appeared to be a simple-to-apply and useful method for the detection of extracellular enzyme activity such as HYAL, protease and SK.

Phenotypic and genotypic characterization of Arcanobacterium haemolyticum isolates from infections of horses

The present study was designed to characterize phenotypically and genotypically seven Arcanobacterium haemolyticum strains obtained from infections of six horses. All seven strains showed the cultural and biochemical properties typical of A. haemolyticum and were susceptible to most of the antibiotics tested. The species identification could be confirmed by amplification and sequencing of the 16S rRNA gene and the 16S-23S rRNA intergenic spacer region and by PCR amplification of species-specific parts of the gene encoding phospholipase D in A. haemolyticum. Use of the latter could possibly improve future identification of this generally human pathogenic bacterial species which, according to the present results, seems to occur also in infections of horses.

The yeast Saccharomyces cerevisiae YDL112w ORF encodes the putative 2'-O-ribose methyltransferase catalyzing the formation of Gm18 in tRNAs

The protein sequences of three known RNA 2'-O-ribose methylases were used as probes for detecting putative homologs through iterative searches of genomic databases. We have identified 45 new positive Open Reading Frames (ORFs), mostly in prokaryotic genomes. Five complete eukaryotic ORFs were also detected, among which was a single ORF (YDL112w) in the yeast Saccharomyces cerevisiae genome. After genetic depletion of YDL112w, we observed a specific defect in tRNA ribose methylation, with the complete disappearance of Gm18 in all tRNAs that naturally contain this modification, whereas other tRNA ribose methylations and the complex pattern of rRNA ribose methylations were not affected. The tRNA G18 methylation defect was suppressed by transformation of the disrupted strain with a plasmid allowing expression of YDL112wp. The formation of Gm18 on an in vitro transcript of a yeast tRNASer naturally containing this methylation, which was efficiently catalyzed by cell-free extracts from the wild-type yeast strain, did not occur with extracts from the disrupted strain. The protein encoded by the YDL112w ORF, termed Trm3 (tRNA methylation), is therefore likely to be the tRNA (Gm18) ribose methylase. In in vitro assays, its activity is strongly dependent on tRNA architecture. Trm3p, the first putative tRNA ribose methylase identified in an eukaryotic organism, is considerably larger than its Escherichia coli functional homolog spoU (1,436 amino acids vs. 229 amino acids), or any known or putative prokaryotic RNA ribose methyltransferase. Homologs found in human (TRP-185 protein), Caenorhabditis elegans and Arabidopsis thaliana also exhibit a very long N-terminal extension not related to any protein sequence in databases.

Studies on biochemical, serological and further characteristics of Streptococcus porcinus

In the present study 70 Streptococcus porcinus isolates could be identified and further characterized by cultural and biochemical properties, by determination of their antibiotic susceptibility and by serological classifications. The S. porcinus included serogroup- and serotype-reference strains, presumptive group candidates and isolates obtained from routine diagnostics. All cultures investigated appeared with a broad zone of beta-haemolysis on sheep blood agar showed a CAMP-like reactivity in the zone of staphylococcal beta-lysin and had the typical biochemical properties of this species. Determination of antibiotic susceptibility revealed a high number of cultures to be susceptible to ampicillin, bacitracin, chloramphenicol, penicillin and vancomycin. Resistances could be observed for erythromycin, minocycline, sulfamethoxazole-trimethoprim, streptomycin and tetracycline. Serogrouping and serotyping could be performed with autoclaved extracts of the bacteria and group- and type-specific antisera prepared against reference strains and group candidates by immunodiffusion reactions. By serogrouping almost all cultures could be classified into serogroup E, U, V or P. Some group E streptococci could additionally be serotyped with type II, VI, VII and group X specific antiserum indicating that group X represents an additional type antigen of serogroup E. None of the antigen preparations reacted with serotype IV, V or group candidate NG1 specific antiserum. The described properties might help to identify and further characterize isolates of the species. S. porcinus, possibly useful in epidemiological aspects.

Use of enzyme tests in characterization and identification of aerobic and facultatively anaerobic gram-positive cocci

The contribution of enzyme tests to the accurate and rapid routine identification of gram-positive cocci is introduced. The current taxonomy of the genera of aerobic and facultatively anaerobic cocci based on genotypic and phenotypic characterization is reviewed. The clinical and economic importance of members of these taxa is briefly summarized. Tables summarizing test schemes and kits available for the identification of staphylococci, enterococci, and streptococci on the basis of general requirements, number of tests, number of taxa, test classes, and completion times are discussed. Enzyme tests included in each scheme are compared on the basis of their synthetic moiety. The current understanding of the activity of enzymes important for classification and identification of the major groups, methods of testing, and relevance to the ease and speed of identification are reviewed. Publications describing the use of different identification kits are listed, and overall identification successes and problems are discussed. The relationships between the results of conventional biochemical and rapid enzyme tests are described and considered. The use of synthetic substrates for the detection of glycosidases and peptidases is reviewed, and the advantages of fluorogenic synthetic moieties are discussed. The relevance of enzyme tests to accurate and meaningful rapid routine identification is discussed.

Identification and epidemiological relationship of Rhodococcus equi isolated from cases of lymphadenitis in cattle

The present study was designed to comparatively investigate 10 Rhodococcus equi isolates from cases of lymphadenitis in cattle. The isolates could be identified by cultural and biochemical properties. By serotyping the R. equi isolates 9 and 1, cultures could be classified as Nakazawa's serotypes 15 and 8, respectively. The isolates did not agglutinate rabbit erythrocytes, were uniformly susceptible to most of the antibiotics tested, did not contain plasmids nor expressed virulence-associated proteins and yielded identical patterns in protein fingerprinting. To further analyze the epidemiological relationships, the isolates were additionally subjected to DNA fingerprinting. This was performed by pulsed-field gel electrophoresis (PFGE) after digestion of the chromosomal DNA with the endonuclease AsnI. PFGE analysis of the chromosomal DNA revealed 4 DNA restriction groups with DNA pattern I with 7 isolates as predominant group and DNA pattern II to IV with one isolate, respectively. The present results indicate that a single R. equi clone belonging to Nakazawa's serotype 15 and according to PFGE to DNA restriction pattern I of the present investigation seems to be responsible for most of the cases of lymphadenitis of cattle described in this study.

Epidemiologic evidence for Lancefield group C beta-hemolytic streptococci as a cause of exudative pharyngitis in college students

The isolation rates of strains of group C beta-hemolytic streptococci from throat swab cultures of patients with exudative pharyngitis, the common cold, and healthy controls were compared. By using a cohort study design in a college health service, patients with exudative pharyngitis were retrospectively identified by description of tonsillar exudate on chart review. Patients with rhinoviral infection were prospectively identified during a common cold study. Healthy controls were prospectively recruited from patients presenting with noninfectious conditions. Isolation of Lancefield group A and C beta-hemolytic streptococci from throat cultures was used as an outcome measurement. A total of 265 students (62% female; average age 20.2 years) with exudative pharyngitis were identified. A total of 75 students (60% female; average age, 21.7 years) from a common cold study with rhinoviral infection were identified. A total of 162 students (53% female; average age, 22.6 years) were recruited as healthy controls. Group A beta-hemolytic streptococci were isolated from 5% of patients with pharyngitis but none of those with rhinovirus (P = 0.045) and none of the controls (P = 0.007). Group C Streptococcus dysglactiae subsp. equisimilis was isolated from 11% of patients with pharyngitis but none of those with rhinovirus (P = 0.006) and 2% of controls (P = 0.001). Lancefield group C Streptococcus anginosus was isolated from 8% of patients with pharyngitis but 3% of those with rhinovirus (P = 0.18) and 1% of controls (P = 0.006). Heavier growth of colonies on the primary culture plate was observed for patients from whom S. equisimilis and group A beta-hemolytic streptococci were isolated. Lancefield group C beta-hemolytic streptococci appear to be associated with exudative pharyngitis in college students.

Comparative studies on streptococci of serological group G isolated from various origins

The streptococcal cultures used in the present study were isolated from dogs, bovines and humans and could be classified into Lancefield's serological group G. Most of the group G streptococci grew in fluid media as granular sediment with clear supernatant and formed compact colonies in soft agar. The majority of the group G streptococci from dogs and bovines displayed CAMP-like synergistic haemolytic activities on sheep blood agar, fermented lactose and salicin and produced the enzyme alpha-D-galactosidase. The group G streptococci from humans mainly fermented trehalose and produced the enzyme beta-D-glucuronidase. In addition, some of the group G streptococci reacted with type antigen X and R and two cultures with M6 specific antiserum. A positive opacity factor reaction could be observed with few group G streptococci isolated from dogs and bovines, but not with those from humans. In binding studies with 125I-labelled plasma proteins most of the cultures interacted with 125I-immunoglobulin G and 125I-albumin. Binding of 125I-IgG was more pronounced among group G streptococci isolated from humans. The determination of antibiotic susceptibility revealed that most of the group G streptococci were susceptible to bacitracin, cefoxitin, clindamycin, erythromycin, gentamicin, penicillin and sulfamethoxazole-trimethoprim. Some of the cultures were resistant to minocycline, neomycin and tetracycline. All this data clearly distinguished group G streptococci isolated from animals and humans and could additionally be used for individual characterization of this microorganism. This might be useful in epidemiological aspects and contribute to understanding infections caused by these bacteria.

Cost-effective, clinically relevant method for rapid identification of beta-hemolytic streptococci and enterococci

Currently popular agglutination and coagglutination methods for the identification of beta-hemolytic streptococci, although rapid and simple to perform, are costly. Furthermore, they fail to distinguish between clinically relevant species and normal flora of the same serogroup. We investigated the use of a series of four physiologic tests to differentiate beta-hemolytic streptococci and enterococci into five clinically relevant groups. We also investigated the use of a new product, Visi-Spot, and evaluated an alternate method for the detection of beta-D-glucuronidase production. Our results suggest that for most routine processing of beta-hemolytic streptococci, physiologic tests are sufficiently rapid, more accurate, and far less costly to perform than serologic methods. The facility of our scheme is enhanced by the use of the Visi-Spot test and the substitution of a commercially available product for more traditional methods of detecting beta-D-glucuronidase.

Biochemical properties and whole-cell protein profiles of group G streptococci isolated from dogs

Whole-cell protein profiles obtained by SDS-PAGE were used in conjunction with physiological tests to differentiate strains of Streptococcus canis isolated from dogs. Fermentation of trehalose and lactose, aesculin hydrolysis together with production of beta-D-glucuronidase and alpha-D-galactosidase allowed the demonstration of nine different biotypes. However, visual analysis of the protein patterns and comparison by the coefficient of Dice showed minor differences in band patterns among strains. Only two different profiles were observed. Although a correlation between biotyping and protein profile has been found, this kind of analysis did not provide the basis for a typing method.

A rapid method for detection of N-acetylglucosaminidase-type chitinase activity in crossed immunoelectrophoresis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels using 4-methylumbelliferyl-N-acetyl-D-glucosaminide as substrate

A method for the detection of N-acetylglucosaminidase (GlcNAcase) activity has been developed by using 4-methyl-umbelliferyl-N-acetyl-D-glucosaminide (4-MU-GlcNAc) as substrate in crossed immunoelectrophoresis (CIE) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gels. Visualization of the reaction with a 366 nm ultra-violet light is possible in approximately 30 min. The method is fast and sensitive in comparison with previous methods. The same band as in SDS-PAGE, showing both GlcNAcase and chitinase activity, was found in the present study; we therefore conclude that this method is also useful in a GlcNAcase-type chitinase assay.

Numerical and chemical classification of Streptosporangium and some related actinomycetes

One hundred and seventeen streptosporangia from soil were compared with marker strains of the family Streptosporangiaceae for many phenotypic properties. The data were examined using the Jaccard, pattern and simple matching coefficients with clustering achieved using average, complete and single linkage algorithms. Particular confidence was placed in the product of the pattern, average linkage analysis given the sharp definition of aggregate groups and clusters and a combination of low test error and high cophenetic correlation values. The test strains were assigned to five aggregate groups that were equated with the genera Streptosporangium (group A), Microbispora (group B), Planobispora and Planomonospora (Group C), Kutzneria (neé Streptosporangium viridogriseum (group D), and Microtetraspora (group E). The streptosporangia, both isolates and marker strains, were assigned to 5 major, 7 minor and 18 single membered clusters. Representative streptosporangia examined for chemical markers were characterised by the presence of meso-diaminopimelic acid in whole-organism hydrolysates, complex mixtures of straight- and branched chain fatty acids, di- and tetrahydrogenated menaquinones as predominant isoprenologues, and complex polar lipid patterns containing diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylinositol, phosphatidylinositol mannosides and uncharacterised components. The chemical and numerical data support the taxonomic integrity of the validly described species of Streptosporangium and suggest that the genus is markedly underspeciated.

Biosystematics and diversity amongst novel carboxydotrophic actinomycetes

Fifty-four carboxydotrophic actinomycetes isolated from soils and composts were compared through 119 unit characters with representative mesophilic and thermophilic streptomycetes. The data were examined using the Jaccard, pattern and simple matching coefficients and clustering achieved using the unweighted pair group method with arithmetic averages algorithm. Acceptable cophenetic correlation and test error values allowed confidence to be placed in the resultant numerical taxonomies. The carboxydotrophic actinomycetes, which were distinct from cluster-groups corresponding to the mesophilic and thermophilic streptomycetes, formed two major cluster-groups the members of which were examined for the presence of diagnostic chemical markers. All but two of the carboxydotrophic actinomycetes had a profile of chemical properties consistent with their assignment to the genus Streptomyces. Quantitative fatty acid data were examined using the SIMCA package and the two statistically significant groups obtained corresponded with the cluster-groups circumscribed in the numerical phenetic analysis. Members of the two groups were also distinguished on the basis of their phospholipid composition. The two strains that contained meso-as opposed to LL-diaminopimelic acid in their peptidoglycan also showed a distinct chemotaxonomic profile. It was concluded that the carboxydotrophic actinomycetes form a novel and taxonomically diverse group.

Role of beta-hemolytic group C streptococci in pharyngitis: incidence and biochemical characteristics of Streptococcus equisimilis and Streptococcus anginosus in patients and healthy controls

The biochemical characteristics and the isolation rates of the two Lancefield group C streptococcal species (S. equisimilis and S. anginosus) from patients with pharyngitis and asymptomatic controls were compared. Some 239 strains of beta-hemolytic group C streptococci were isolated from 1,480 patients (209 strains) with pharyngitis and 227 controls (30 strains). A total of 44 strains displayed broad hemolysis, were Voges-Proskauer test negative, and produced glucuronidase. Some 72.7% of these strains also fermented ribose. A second group of 159 strains was Voges-Proskauer test positive and glucuronidase negative; 98.8% also displayed minute hemolysis and only 3.7% fermented ribose. These two groups represent typical large-colony S. equisimilis and small-colony S. anginosus, respectively. A small number of strains (36 in total) exhibited intermediate characteristics; morphologically, all 36 strains resembled S. anginosus, but 6 strains biochemically resembled S. equisimilis. No strains of S. equisimilis fermented sorbitol (unlike S. zooepidemicus) and all fermented trehalose (unlike S. equi). The structural carbohydrate profiles of S. equisimilis and S. anginosus both included galactosamine (consistent with their being group C organisms), but the profiles were not distinguishable. In total, 78.5% of strains from controls and 83.3% of strains from patients were determined to be the species S. anginosus. S. equisimilis was isolated from 3.0% of patients and 2.2% of controls, and S. anginosus was isolated from 11.1% of patients and 11.0% of controls. Thus, S. equisimilis and S. anginosus are both members of the normal flora of asymptomatic individuals. The incidence and biochemical characteristics of these two species are similar in patients who are healthy and those who have disease. However, a companion article provides clinical evidence associating S. equisimilis (but not s. anginosus) with pharyngitis.

Quantitative fluorometric assay for rapid enzymatic characterization of Bifidobacterium longum and related bifidobacteria

The quantitative, semi-automated assay described here is an alternative characterization method allowing for highly sensitive and specific detection of bifidobacterial enzymes. Twenty strains of Bifidobacterium longum, including the type strain ATCC 15707, and type strains of 15 other Bifidobacterium species were enzymatically characterized using 20 4-methylumbelliferyl conjugated substrates. Enzyme activities were determined by directly measuring the intensity of fluorescence derived from 4-methylumbelliferone, a fluorescent metabolic by-product. For this method, a Titertek Fluoroskan II fluorometer was used. Enzymes included glycosidases, an esterase, phosphatase, sulphatase, and neuraminidase. B. longum showed strong activity (greater than 1,000 absolute fluorescence units, afu) for alpha-L-Arabinopyranosidase and alpha-L-Arabinofuranosidase, beta-D-Fucosidase, alpha- and beta-D-Galactosidase, alpha-D-Glucosidase, and alpha-D-Mannosidase. No activity (less than or equal to 50 afu) was observed for beta-D-Cellobiosidase, alpha- and beta-L-Fucosidase, beta-D-Glucuronidase, beta-D-Mannosidase, Neuraminidase and Sulphatase. Enzymatic activity profiles in other bifidobacteria were different according to the species. This assay is simple and rapid (6 hr). Special cultural requirements are unnecessary. Results are objective and quantitative. This assay may be a useful tool for bifidobacterial taxonomy.

Beta-D-glucuronidase activity assay for rapid differentiation of species within beta-haemolytic group C and G streptococci

Methylumbelliferyl-conjugated enzyme substrates were assessed for their ability to differentiate beta haemolytic streptococci in Lancefield groups C and G. Both Streptococcus equisimilis (group C) and large colony human biotype group G strains were consistently differentiated from group C and G "Streptococcus milleri group" bacteria by their ability to hydrolyse the beta-D-glucuronide substrate. The test was completed in less than one hour.

Evaluation of two fluorogenic assays for identification of Streptococcus species isolated from bovine mammary glands

Liquid and agar assays that utilized 4-methylumbelliferyl-conjugated beta-D-glucuronide, beta-D-galactoside, or N-acetyl-beta-D-glucosaminide, and agglutination by Dolichos biflorus lectin were evaluated for identification of Streptococcus species isolated from bovine mammary glands. A greater number of Streptococcus uberis isolates were negative for N-acetyl-beta-D-glucosaminidase by the liquid assay compared with the agar assay. Enzyme profiles for Streptococcus dysgalactiae were similar by both assays. Streptococcus dysgalactiae was the only species that agglutinated when mixed with lectin from D. biflorus. Most Streptococcus agalactiae isolates were positive for beta-D-glucuronidase and beta-D-galactosidase by both assays. Two Streptococcus equinus strains had negative enzyme profiles by the liquid assay; however, both strains had enzyme profiles consistent for S. equinus by the agar method. Incorporation of 4-methylumbelliferyl-conjugated substrates into trypticase soy agar did not appear to alter agar characteristics and eliminated aliquoting substrates and inoculating tubes. More than one enzyme profile was produced per Streptococcus species or serogroup by both methods. However, some profiles were similar between species, which hindered accurate identification of Streptococcus species.

Lectins and their application to clinical microbiology

Lectins are generally associated with plant or animal components, selectively bind carbohydrates, and interact with procaryotic and eucaryotic cells. Lectins have various specificities that are associated with their ability to interact with acetylaminocarbohydrates, aminocarbohydrates, sialic acids, hexoses, pentoses, and as other carbohydrates. Microbial surfaces generally contain many of the sugar residues that react with lectins. Lectins are presently used in the clinical laboratory to type blood cells and are used in a wide spectrum of applications, including, in part, as carriers of chemotherapeutic agents, as mitogens, for fractionation of animal cells, and for investigations of cellular surfaces. Numerous studies have shown that lectins can be used to identify rapidly certain microorganisms isolated from a clinical specimen or directly in a clinical specimen. Lectins have been demonstrated to be important diagnostic reagents in the major realms of clinical microbiology. Thus, they have been applied in bacteriology, mycology, mycobacteriology, and virology for the identification and/or differentiation of various microorganisms. Lectins have been used successfully as epidemiologic as well as taxonomic markers of specific microorganisms. Lectins provide the clinical microbiologist with cost-effective and potential diagnostic reagents. This review describes the applications of lectins in clinical microbiology.

Rapid detection of herpes simplex virus with fluorescein-labeled Helix pomatia lectin

The use of fluorescein-conjugated Helix pomatia lectin was shown to be as effective as fluorescein-conjugated monoclonal antibody reagents for the detection and differentiation of herpes simplex virus type 1 and type 2 (HSV-1 and HSV-2) in MRC-5 cell culture. Cells infected with HSV-1 generally displayed a pattern of nongranular or diffuse fluorescence, while cells infected with HSV-2 were identified by the production of fluorescent grains and flecks. This unique nonimmunological reagent, when used in combination with low-speed centrifugation, provides a remarkably specific, sensitive, rapid, and cost-effective means to detect HSV-infected MRC-5 or BHK-21 cells as early as 20 h postinoculation. In contrast to the immunofluorescence method, the serotypes of HSV can be differentiated with only one fluorescein-H. pomatia reagent in MRC-5 cell cultures.

Universal immuno-stick test for direct rapid identification of microbial antigens within 5 minutes. Preliminary report

Based on experiences with ELISA and biochemical fluorescence assays we have developed a new serologic identification system for detecting all conceivable particle and soluble antigens within 5 min using a very simple, sensitive procedure. This assay represents a sandwich ELISA that has been modified with regard to the sorbent, the enzyme substrate and the identification step. The test is performed as follows: 10 microliter aliquots of antigen dilution, specific or control antibody, respectively, and a phosphatase-conjugated anti-antibody are consecutively mixed. A small strip of special indicator sorbent paper (test stick) is moistened with this mixture for one minute. Subsequently it is dipped 3-5 times alternately in 0.1 M NaOH and a solution of the enzyme-substrate 4-methylumbelliferyl phosphate and immediately evaluated under a UV lamp. Positive samples instantaneously show brilliant light blue fluorescence and decolorization from dark red to white. Although the principle behind the reaction is not yet fully understood, the test works specifically and sensitively within a pg range. Thus far, for example, we have been able to identify Salmonella from suspended milk powder and streptococci from milk (3-5 cells/ml) without previous incubation, enterotoxins from staphylococcal colonies, Aflatoxin M1 and organ-phosphates. Results from examinations of staphylococcal enterotoxins are presented in more detail. Moreover, using a defined antigen, antibodies from different sera could be identified in the same rapid, sensitive and specific manner. Thus, we are convinced that the usual time-consuming enrichment methods for isolating pathogenic bacteria and other immunogenic substances as also current serologic assays will turn out to be superfluous.

Comparative studies on Actinomyces pyogenes and Arcanobacterium haemolyticum

Actinomyces pyogenes and Arcanobacterium haemolyticum were further characterized. A. haemolyticum, in contrast to A. pyogenes, gave synergistic hemolytic reactions with streptococci of serological group B and inhibited staphylococcal beta-hemolysis. A. pyogenes and A. haemolyticum had a number of common, as well as distinctly different enzymatic properties, useful for their characterization. Extracts from A. pyogenes reacted with antiserum against streptococci of serological group G in contrast to those from A. haemolyticum.

Detection of specific bacterial enzymes by high contrast metal chelate formation. Part II. Specific detection of Escherichia coli on multipoint-inoculated plates using 8-hydroxyquinoline-beta-D-glucuronide

The use of 8-hydroxyquinoline-beta-D-glucuronide for the demonstration of beta-glucuronidase activity within the family Enterobacteriaceae has been investigated. The compound has been shown to be an effective substrate for the bacterial enzyme and the Michaelis constant for the association has been determined. A multipoint-inoculated method was employed to test 400 routine clinical isolates including those of urinary and faecal origin. When grown on an agar-based medium containing the substrate together with a ferric salt, glucuronidase-positive organisms were revealed by intense black pigmentation located only in the colony mass. The only organism yielding positive results by this method was Escherichia coli. The shigellae tested were negative by this procedure. Of the total biochemically profiled E. coli organisms 80% were specifically visualised by the method. This contrasts with 97% positively obtained by a fluorescence procedure involving use of 4-methylumbelliferone-beta-D-glucuronide but which also gives positive results with Shigella sonnei. A simple, cost-effective procedure involving use of both techniques for specific detection of E. coli is described.

Identification of group B streptococcal antigen with lectin-bound polystyrene particles

The lectin of the tomato, Lycopersicon esculentum, or of the potato, Solanum tuberosum, can be passively coupled to amide-modified polystyrene spheres to be used as a detection reagent for the specific identification of group B streptococcal cultures grown in selective or nonselective Todd-Hewitt broth for 5 and 4 h, respectively. Agglutination occurred when the lectin reagents were allowed to react with either the cell suspension, clarified broth, or antigen extracts from group B streptococci grown in Todd-Hewitt broth. No agglutination occurred when these lectins were allowed to react with strains of serogroup A, C, D, F, or G streptococci. False-negative agglutination responses may occur with certain serotype of group B streptococci grown on Columbia sheep blood agar. A 20-min staining time permitted the specific labeling of fixed smears of group B streptococci with fluorescein-conjugated Lycopersicon lectin. The lectin from the solanaceous plant Datura stramonium did not agglutinate group B streptococci or other clinically significant streptococcal serogroups.

A rapid test for chitinase activity that uses 4-methylumbelliferyl-N-acetyl-beta-D-glucosaminide

A total of 101 strains of bacteria from environmental and clinical sources, most of which were gram negative, were tested for chitobiase activity by using a filter paper spot test with 4-methylumbelliferyl-N-acetyl-beta-D-glucosaminide as the substrate. The results were compared with those obtained by a conventional plate method for chitinase activity by using colloidal chitin as the substrate. There was excellent agreement in the results for both methods. The filter paper spot test with 4-methylumbelliferyl-N-acetyl-beta-D-glucosaminide has the advantages of being rapid, simple to perform, and inexpensive. This method should be adaptable to a wider range of microorganisms, particularly those with unusual growth requirements.

Rapid differentiation of streptococci isolated from cows with mastitis

The demonstration of some species-specific streptococcal enzymes with 4-methylumbelliferyl-conjugated beta-D-glucuronide, N-acetyl-beta-D-glucosaminide, and beta-D-mannoside and agglutination with the lectin from Dolichos biflorus allowed rapid tentative identification of streptococci isolated from cows with mastitis.

beta-D-galactosidase activity in streptococci of serological group B

Group B streptococci isolated from humans differed significantly in beta-D-galactosidase-activity from those of bovine mastitis. This could be demonstrated in a relatively simple and rapid test using a fluorogenic 4-methylumbelliferyl-beta-D-galactoside conjugate. Only 10 (12%) of 82 group B streptococcal cultures from human produced beta-D-galactosidase. On the other hand, 74 (96%) of 77 "bovine" cultures formed this enzyme. Thus, beta-D-galactosidase activity could be used as an additional marker for the differentiation between group B streptococci of human and bovine origin.

Incidence and characterization of beta-hemolytic Streptococcus milleri and differentiation from S. pyogenes (group A), S. equisimilis (group C), and large-colony group G streptococci

The biochemical characteristics of 172 clinical isolates of group A, C, F, or G or "nongroupable" beta-hemolytic streptococci were examined. Among these isolates, 91 were identified as beta-hemolytic strains of Streptococcus milleri. The remaining isolates included 20 Streptococcus pyogenes, 21 Streptococcus equisimilis, 37 large-colony group G streptococci, and 3 unidentified nongroupable isolates. A majority (84%) of the S. milleri strains possessed Lancefield group antigen (3 A, 27 C, 41 F, and 5 G), whereas 15 S. milleri strains (16%) were nongroupable. Serological tests did not differentiate S. milleri isolates with group A, C, or G antigen from S. pyogenes (group A), S. equisimilis (group C), or large-colony group G streptococci. Biochemical tests which were found useful for differentiation included the Voges-Proskauer test, hydrolysis of pyroglutamic acid and beta-D-glucuronide, bacitracin susceptibility, and acid production from ribose. S. milleri represented 56% of the group C, 100% of the group F, and 83% of the nongroupable beta-hemolytic streptococci isolated in our clinical laboratory, whereas the incidence of S. milleri among group A and group G streptococci was estimated to be low. The role of beta-hemolytic S. milleri as a cause of human infection remains obscured by the failure to routinely differentiate S. milleri from other beta-hemolytic streptococci.

Biotyping and exoenzyme profiling as an aid in the differentiation of human from bovine group G streptococci

Group G streptococci were isolated from throat and extrapharyngeal cultures from 75 patients during an 18-month period. Of 29 throat isolates, 18 were recovered from patients with pharyngitis, 8 were of unknown significance, and 3 were of questionable etiology. Clinical significance could be ascribed to 13 of 46 extrapharyngeal isolates recovered from wound, urinary tract, blood, and conjunctival cultures. Extrapharyngeal isolates recovered from stool, sputum, and vaginal cultures were considered nonsignificant. A total of 96 group G streptococcal strains (including 21 human and 14 bovine strains from outside sources) were tested for exoenzyme production and subjected to a large battery of biochemical tests. Bovine and human isolates could be distinguished on the basis of trehalose fermentation, litmus milk reduction, and production of beta-D-glucuronidase, hyaluronidase, and fibrinolysin. Eight distinct biotypes could be discerned on the basis of fermentation of trehalose, raffinose, and lactose and esculin hydrolysis. All isolates that fermented raffinose were associated with infection. These results support the concept of two distinctly different epidemiological reservoirs of group G streptococci in humans and bovines.

Identification of group C streptococcal antigen extracts with lectin-bound polystyrene particles

Crude extracts of Dolichos biflorus can be coupled to polystyrene particles to yield an agglutination reagent for the detection of group C streptococcal antigen extracts. The reagent is relatively inexpensive and simple to prepare and can be employed for the definitive identification of this beta-hemolytic streptococcus.