New method for the serological grouping of Streptococci with specific antibodies adsorbed to protein A-containing staphylococci

Detection and comparison of neuraminidase activities in human and bovine group B streptococci

Human and bovine group B streptococcus (GBS) isolates were serotyped and amounts of released N-acetylneuraminic acid from N-acetylneuraminyl-lactose by extracellular neuraminidase were colorimetrically assessed. According to serotyping by co-agglutination method, 30 of bovine GBS and 43 of human GBS could be serotyped (ST) by monospecific antisera coated with protein A. The remaining GBS strains were designated as nontypeable (NT). The released N-acetylneuraminic acid was determined in 90.9% of bovine GBS and 47.1% of human GBS isolates. The differences between the total bovine and human GBS isolates were statistically significant (p < 0.001). In comparison with detected N-acetylneuraminic acid level in bovine and human groups, significant decrease was observed in the bovine NT group according to increased human NT (p < 0.01) and bovine ST groups (p < 0.01). However, N-acetylneuraminic acid level in bovine ST and bovine total groups significantly (p < 0.001) increased with respect to the human ST group and human total group. Neuraminidase activity was detected more frequently in bovine GBS isolates. Considerable differentiations were observed between typeable and nontypeable isolates.

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.

Current methods for capsular typing of Streptococcus pneumoniae

Streptococcus pneumoniae is a major respiratory tract pathogen causing pneumococcal disease mainly in children aged less than five years and in the elderly. Ninety-eight different capsular types (serotypes) of pneumococci have been reported, but pneumococcal conjugate vaccines (PCV) include polysaccharide antigens against only 7, 10 or 13 serotypes. It is therefore important to track the emergence of serotypes due to the clonal expansion of non-vaccine serotypes. Increased numbers of carried and disease-causing pneumococci are now being analysed as part of the post-PCV implementation surveillance studies and hence rapid, accurate and cost-effective typing methods are important. Here we describe serotyping methods published prior to 10th November 2014 for pneumococcal capsule typing. Sixteen methods were identified; six were based on serological tests using immunological properties of the capsular epitopes, eight were semi-automated molecular tests, and one describes the identification of capsular type directly from whole genome data, which also allows for further intra and inter-genome analyses. There was no single method that could be recommended for all pneumococcal capsular typing applications. Although the Quellung reaction is still considered to be the gold-standard, laboratories should take into account the number of pneumococcal isolates and the type of samples to be used for testing, the time frame for the results and the resources available in order to select the most appropriate method. Most likely, a combination of phenotypic and genotypic methods would be optimal to monitor and evaluate the impact of pneumococcal conjugate vaccines and to provide information for future vaccine formulations.

Methenamine-hippurate and bacteriuria in the geriatric patient with a catheter

Oral treatment with methenamine-hippurate (MH) in patients with an indwelling catheter has been found to reduce the need of frequent catheter exchange and the number of symptomatic infections. Bacteriuria, however, persists during MH treatment. The hypothesis that the therapeutic effect is due to a reduction in the number of bacteria, or a change in the pattern of strains was tested in a crossover study (2 x 6 weeks). MH treatment, 1 g twice daily, was compared to control periods in 52 patients. The majority of quantitative and qualitative bacterial cultures at 2-week intervals yielded 2--4 strains. Of the bacterial isolates, 50% were found on 4--6 occasions out of 6 possible. MH treatment had no significant influence on the pattern of various strains. A 30% decrease in the mean total bacterial count during MH treatment did not reach statistical significance (p approximately 0.07). It is suggested that prevention of catheter complications during MH treatment may be due to a physiochemical action on salt formation rather than a direct antibacterial effect.

Characterization of bovine and human group B streptococci isolated in Turkey

In the study, group B streptococci (GBS) isolated from bovines and humans in and around Van, eastern Turkey, were serotyped, and their haemagglutination and lectin-agglutination properties were also determined. This study is the first epidemiological survey of GBS serotypes performed in Turkey. A total of 148 GBS isolates, 76 from bovine milk and 72 from women attending a maternity polyclinic, were examined by co-agglutination, slide haemagglutination and slide lectin-agglutination tests. By the co-agglutination test, 34 (44.7%) of bovine isolates and 49 (68%) of human isolates could be serotyped. In bovine isolates, type VII (11.8%), III (10.5%), Ic (6.5%) and VIII (3.9%) were the most frequently detected serotypes. The most frequent human serotypes were Ic (33.3%), IV (8.3%), VIII (6.9%), V (5.5%) and R (5.5%). In the haemagglutination test using rabbit erythrocytes, 23 (33.3%) bovine and 15 (23.4%) human isolates were found to be positive. The bovine GBS isolates showed a significant positive agglutination reaction with Dolichos biflorus lectin (30.4 %), whereas the human GBS isolates were found to be positive for Arachis hypogea (18.8%) and Canavalia ensiformis (37.5%) lectins. The treatment of GBS with trypsin was also found to be important for the demonstration of the haemagglutination and lectin-agglutination properties of GBS. The results of the study provide data on serotype distribution and the formulation of a possible GBS vaccine in Turkey, and the lectin-agglutination tests may also be useful for differentiating bovine and human GBS strains.

Distribution of antimicrobial resistance and virulence-related genes among Brazilian group B streptococci recovered from bovine and human sources

In the present report we describe the characteristics of 189 antimicrobial-resistant Streptococcus agalactiae isolates from bovine (38 isolates) and human (151 isolates) sources. All the strains were resistant to tetracycline (TET), and 16 (8.5%) were also resistant to erythromycin, corresponding to 23.7% of the TET-resistant bovine isolates and 4.6% of the TET-resistant human isolates. The tet(O), erm(B), and mreA resistance-related genes, as well as the bca and scpB virulence-related genes, were the most frequent among the bovine isolates, while the tet(M), erm(A), mreA, bca, lmb, and scpB genes were the most prevalent among the isolates from humans. Although a few major clusters were observed, pulsed-field gel electrophoresis results revealed a variety of profiles, reflecting the substantial genetic diversity among strains of this species isolated from either humans or bovines.

Phenotypic and molecular characteristics of Streptococcus agalactiae isolates recovered from milk of dairy cows in Brazil

Information on the characteristics of Streptococcus agalactiae obtained from bovine sources in Brazil is still very limited. The aim of this study was to assess the phenotypic and genotypic diversity among S. agalactiae isolates from milk of dairy cows presenting clinical or subclinical mastitis in the southeast region of Brazil. Phenotypic characterization was based on physiological and serological tests. Antimicrobial susceptibility tests were carried out by the disk method. Genetic diversity was evaluated by using random amplified polymorphic DNA-PCR (RAPD-PCR) (by using the primer 1254) and pulsed-field gel electrophoresis (PFGE) (by using SmaI as the restriction enzyme) and by PCRs for detection of genes associated with resistance to erythromycin and tetracycline as well as PCRs for detection of genes coding for cell surface-associated proteins. According to the results of physiologic tests, 45 (52.9%) isolates showed beta-hemolysis and 44 (51.7%) were susceptible to bacitracin. Fourteen different biotypes were detected. The two most frequent biotypes comprised strains that were non-beta-hemolytic; fermented galactose, lactose, and salicin; produced protease; and were negative for DNase production. Serotype III was predominant (66 isolates [77.6%]), followed by serotypes II, Ia, Ib, and VI. Resistance to tetracycline and erythromycin was found in 38 (44.7%) and 9 (10.5%) isolates, respectively, with tet(O) (31.7%) and erm(B) (100%) being the most frequently occurring resistance genes. Three genes coding for surface proteins, bca, lmb, and scpB, were detected in 55 (64.7%), 7 (8.2%), and 43 (50.5%) isolates, respectively. In most cases, isolates from animals in the same herd presented closely related genetic profiles (determined by either RAPD-PCR or PFGE), which were distinct from those of isolates from different herds.

Binding of murine myeloma proteins of different Ig classes and subclasses to Fc-reactive surface structures in gram-positive cocci

Twelve different murine myeloma proteins were tested for binding to seventy Gram-positive strains belonging to group A, C and G streptococci and to Staphylococcus aureus. Group A streptococci, known to bind human IgG, were incapable of binding any of eight murine IgG immunoglobulins tested except for one strain that bound an IgG2b myeloma protein. In contrast, group C and G streptococci interacted with murine immunoglobulins of subclasses IgG2a, IgG2b and IgG3, and G strains also to a lesser extent with IgG1. Bovine and equine-group C streptococci did not differ from human group C streptococci in their IgG reactivity. Staphylococcal strains showed a high reactivity with murine myeloma components of IgG subclasses 2a, 2b and 3 and a low but definite binding of an IgG1 myeloma protein. IgA myeloma protein S-122 interacted with nine of fifteen group A streptococci. This binding could not be inhibited by human IgG and the reactivity is thus different from Fc-mediated binding of immunoglobulins. One of three IgA myeloma proteins tested, TEPC 15, bound to staphylococci. The Fc specificity of this interaction was confirmed by chromatography on protein A-Sepharose and by inhibition studies using polyclonal human IgG. The protein A reactivity of this monoclonal protein was detected in IgA aggregates and absent in the monomeric form of IgA.

Coagglutination test for serotyping Pasteurella haemolytica

A coagglutination test was described for simple, fast, and reliable detection of Pasteurella haemolytica type-specific antigens in lung lesions even in the absence of viable P. haemolytica. The coagglutinating reagents were prepared by coating protein A-producing Staphylococcus aureus cells with hyperimmune sera raised against P. haemolytica type strains. Bacterial suspensions, saline extracts, and boiled saline extracts of the bacteria were used as antigens. Homologous reactions with all types of antigens were precise. Some cross-reactions were similar to those obtained by the indirect hemagglutination test, and some additional one-way cross-reactions were identified. The coagglutination test was used for serotyping 65 P. haemolytica field strains and for the detection of P. haemolytica type-specific antigens in the lung specimens of 62 calves and 78 sheep. Ninety-four percent of the field strains could be serotyped by the coagglutination test. P. haemolytica type-specific antigens were detected in the lung specimens of 3 calves and 5 sheep that had succumbed to naturally occurring P. haemolytica pneumonia and in the lungs of 20 calves experimentally infected with P. haemolytica A1. The coagglutination test detected type-specific antigens in 36% of the lung specimens of slaughtered field sheep but not in the lungs of slaughtered field cattle with small chronic lung lesions. No reaction occurred in the case of nonpneumonic calves and sheep or when pneumonic lesions were caused by other bacteria. No P. haemolytica strains could be isolated from lung samples that were coagglutination test negative. This test is recommended as an additional method for fast and reliable serotyping of P. haemolytica.

Use of polyvalent coagglutination reagents for serotyping of Streptococcus suis

Polyvalent coagglutination reagents (PRs) have been evaluated for the serotyping of Streptococcus suis. Monovalent antisera produced against 28 S. suis reference strains have been grouped to obtain five different pools. A total of 249 field isolates previously identified and belonging to different serotypes were tested with PRs prepared by two different procedures: (i) monovalent coagglutination reagents were individually prepared and mixed in equal proportions, and (ii) antisera were mixed in equal proportions before the addition of the Staphylococcus aureus suspension. Only antisera tested by a tube agglutination test with 2-mercaptoethanol and presenting titers of 1:32 or higher were used. Results obtained with PRs prepared by both procedures were similar, and there was a very good correlation between the capsular type of the isolate and the reaction obtained with PRs. Thus, from a practical viewpoint, it is suggested that PRs be prepared by the first procedure. To isolates, were tested in parallel with both the PRs and the monovalent coagglutination reagents over a 1-year period. Ninety-nine percent of the typeable and all of the untypeable isolates were correctly identified. Serotyping with PRs is suggested to be a very useful and reliable screening procedure, particularly when a large number of S. suis isolates have to be serotyped. In addition, the choice of antisera to be included in a given pool is facultative and should be oriented to the needs of a region or a country.

Protein rib: a novel group B streptococcal cell surface protein that confers protective immunity and is expressed by most strains causing invasive infections

The group B Streptococcus, an important cause of invasive infections in the neonate, is classified into four major serotypes (Ia, Ib, II, and III) based on the structure of the polysaccharide capsule. Since the capsule is a known virulence factor, it has been extensively studied, in particular in type III strains, which cause the majority of invasive infections. Two cell surface proteins, alpha and beta, have also been studied in detail since they confer protective immunity, but these proteins are usually not expressed by type III strains. We describe here a cell surface protein, designated protein Rib (resistance to proteases, immunity, group B), that confers protective immunity and is expressed by most strains of type III. Protein Rib was first identified as a distinct 95-kD protein in extracts of a type III strain, and was purified to homogeneity from that strain. Rabbit antiserum to protein Rib was used to demonstrate that it is expressed on the cell surface of 31 out of 33 type III strains, but only on 1 out of 25 strains representing the other three serotypes. Mouse protection tests showed that antiserum to protein Rib protects against lethal infection with three different strains expressing this antigen, including a strain representing a recently identified high virulence type III clone. Protein Rib is immunologically unrelated to the alpha and beta proteins, but shares several features with the alpha protein. Most importantly, the NH2-terminal amino acid sequences of the Rib and alpha proteins are identical at 6 out of 12 positions. In addition, both protein Rib and the alpha protein are relatively resistant to trypsin (and Rib is also resistant to pepsin) and both proteins vary greatly in size between different clinical isolates. Finally, both protein Rib and the alpha protein exhibit a regular ladderlike pattern in immunoblotting experiments, which may reflect a repetitive structure. Taken together, these data suggest that the Rib and alpha proteins are members of a family of proteins with related structure and function. Since protein Rib confers protective immunity, it may be valuable for the development of a protein vaccine against the group B Streptococcus, an encapsulated bacterium.

Liquid medium for rapid presumptive identification of group B streptococci

A suitable test was developed for distinguishing group B streptococci from other beta-hemolytic streptococci during growth in liquid medium. One hundred and sixty of 161 human group B strains tested yielded positive reactions within a 5 h incubation. The dye medium tested is a reliable substitute for more expensive serological procedures.

Pesquisa do antígeno circulante de Cryptococcus neoformans em líquido cefalorraqueano pelo teste de coaglutinação

Foram utilizadas 82 LCR de transplantados renais (24 pacientes), 43 LCR de pacientes com críptococose comprovada (controles positivos), 35 LCR de pacientes com outras doenças (histoplasmose, paracoccidioidomicose e infecções bacterianas) como controles negativos. Os primeiros foram cultivados em ágar Sabouraud com sementes de girassol e juntamente com os demais examinado pelo teste de látex para pesquisa de antígeno circulante de C. neoformans, qualitativamente. O teste de Coaglutinação foi realizado qualitativamente e quantitativamente, encontrando-se títulos até a diluição 1:2048. Não foram detectadas reações falso-positivas ou falso-negativas entre os controles. Como prova de valor diagnóstico demonstrou: sensibilidade - 92,1%; especificidade - 92,6% e eficiência - 92,3%. Provou também ser um teste rápido, exato e econômico, embora sua escolha dependa do pré-tratamento de LCR (80ºC por 3 a 5 minutos) e soros (diluição ou álcali-precipitação) para evitar autoaglutinação e aumentar a sensibilidade da reação.

Intraepithelial stage of signet-ring cell carcinoma of the stomach

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Inhibition of platelet aggregation by a whole cell extract from strains of group B streptococcus

A whole cell extract (HCl-Ext) from strains of group B streptococci (GBS) possessing fibrinogen binding activity prevented the platelet aggregation induced with adenosine 5'-diphosphate (ADP), collagen and thrombin, while aggregation by epinephrine and ristocetin was slightly inhibited and arachidonic acid-induced platelet aggregation was not affected whatsoever. When the HCl-Ext was added after commencement of the aggregation, deaggregation was observed in cases induced by ADP, collagen, and thrombin. By precoating the washed platelets with HCl-Ext, both of ADP- and collagen-induced platelet aggregation were suppressed. The active factor in the HCl-Ext seemed to be undialyzable, trypsin-susceptible, and proteinaceous substance, unlike GBS polysaccharide type antigen.

Outbreaks of infections with erythromycin-resistant group A streptococci in child day care centres

Erythromycin-resistant group A streptococci (ERGAS) are considered rare in Sweden. In the county of Halland (240,000 inhabitants) in southern Sweden, we had 294 isolates of ERGAS between January 1984 and June 1985. Almost all strains were of T-type 12 and only resistant to erythromycin (MIC values approximately 8 g/l). Seven child day care centres (DCC) were involved in the outbreaks and on average 49% of all children were infected in each outbreak. Employees were seldom infected (8%), but parents and siblings more often (23% and 36%). One course of phenoxymethylpenicillin succeeded in eradicating ERGAS from 75% of those infected. The ERGAS strains are now established in southern Sweden and account for about 2% of all group A streptococcal infections in the county of Halland.

Protein G genes: structure and distribution of IgG-binding and albumin-binding domains

Protein G (also designated Fc receptor type III) is the IgG-binding protein of group C and G streptococci. Protein G has also been shown to bind human serum albumin but at a site that is structurally separated from the IgG-binding region. From the known gene sequence of protein G, two synthetic oligonucleotides were constructed for use as probes in DNA-hybridization experiments to study the structure and distribution of the albumin- and IgG-binding regions in bacterial strains belonging to different species. Thus, one of the probes corresponded to repeats within the IgG-binding region (I) and the other corresponded to repeats in the albumin-binding encoding region (II). Probe I showed strong hybridization to DNA isolated from 31 human group C and G strains, whereas hybridization to probe II was variable. With the three restriction endonucleases used, three restriction patterns were found in Southern blot experiments. No fundamental difference could be detected in hybridization experiments, either between strains of group C and G streptococci, or between isolates of different clinical origin. No hybridization to DNA from other bacterial species was found.

Rapid serotyping of enteropathogenic Yersinia enterocolitica strains by co-agglutination

A rapid co-agglutination test using monospecific antisera was developed for the serological typing of enteropathogenic strains of Yersinia enterocolitica. A total of 70 bacterial strains (17 reference strains and 53 clinical isolates) were examined. Absorption of immune sera against serotypes O:3, O:8 and O:9 with their heterologous antigens (S-LPS) was necessary to avoid the appearance of different cross-reactions, as observed by co-agglutination. The proteins present in the S-LPS preparations obtained from each serotype seemed to be responsible for such cross-reactions. Results obtained with a total of 57 clinical isolates belonging to other members of the family Enterobacteriaceae indicate a high specificity of the assay.

Cross-reactions between pneumococci and other streptococci due to C polysaccharide and F antigen

By serological methods, all 83 known types of Streptococcus pneumoniae could be shown to possess C polysaccharide and F antigen. Cross-reactions due to these two antigens between pneumococci and a broad range of most other commonly encountered streptococci were examined. The presence of an antigen closely similar or identical to pneumococcal C polysaccharide was demonstrated in some strains of Streptococcus mitior. Therefore, we conclude that pneumococci cannot be identified serologically from mixed samples without culture. Streptococcal group C antiserum was found to cross-react with pneumococcal F antigen.

Clinical and laboratory findings in patients with acute tonsillitis

In 82 patients with acute tonsillitis studied, beta-hemolytic group A streptococci were isolated from 30 (37%), and group C or G streptococci from 12 (15%). In the 40 patients with non-streptococcal tonsillitis there was a significantly higher isolation rate of pneumococci, H. influenzae and/or B. catarrhalis, as compared with those with beta-hemolytic streptococci. Patients were classified regarding clinical status according to standardized criteria as severe, moderate, or mild. The patients with group A streptococcal tonsillitis were significantly more often classified clinically as 'severe' and had significantly shorter duration of symptoms before seeking medical care, as compared with those with non-streptococcal tonsillitis. Significant increases in white blood cell count and in anti-DNase B were found in the patients with group A streptococcal tonsillitis, whereas their antistreptolysin O levels did not increase significantly. C-reactive protein concentrations were consistently higher in the patients with group A streptococcal tonsillitis. No evidence of polyclonal beta-lymphocyte stimulation was found when measuring antibodies against pneumococci and group B streptococci. The findings show clinical and simple laboratory tests to be useful aids in distinguishing group A streptococcal tonsillitis from non-streptococcal tonsillitis, and that other bacteria may be involved in non-streptococcal tonsillitis.

Isolation of a specific albumin receptor from a group G streptococcal strain

The albumin receptor, a bacterial cell-wall protein with affinity for albumin, has been isolated from a bovine group G streptococcal strain (DG-8). Bacterial surface proteins were solubilized by boiling in 0.6M HCl for 5 min. The albumin receptor was isolated by sequential use of ion-exchange chromatography on DEAE-Sephadex A-50 and affinity chromatography on albumin coupled Sepharose 4B. The presence of albumin receptor in various pools and fractions during the isolation was followed by their ability to inhibit the binding of radiolabelled albumin to DG-8 bacteria. A highly purified albumin receptor was obtained according to Western blot analysis. The albumin binding band obtained showed a molecular weight of about 30,000. The purified receptor did not possess any IgG binding capacity. 50 micrograms albumin receptor was prepared from each gram of bacteria.

Penicillin tolerance in beta-streptococci isolated from patients with tonsillitis

Beta-streptococci isolated from patients with acute tonsillitis were tested for penicillin tolerance defined as an MBC/MIC ratio greater than or equal to 16. 11/18 strains recovered from patients with clinical treatment failure were tolerant to penicillin in comparison with 0/15 strains from successfully treated patients. The MBC/MIC ratio was less than 16 for all strains versus cefadroxil but above that ratio for many strains versus clindamycin, doxycycline and erythromycin. We suggest that penicillin tolerance may be one reason to treatment failures in individuals with streptococcal tonsillitis and that other antibiotics could be used to treat these patients since penicillin tolerance is not correlated to a general increase in antibiotic resistance.

Evaluation of a two-minute strep A direct swab test (SADST) on patients with pharyngitis at a primary care clinic

A two-minute strep A direct swab test (SADST) was used to detect the presence of Lancefield group A streptococci (GAS) from the throats of 207 patients with pharyngitis at a primary-care clinic. The results were compared with a standard culture method. Fifty-one specimens were positive and 156 specimens were negative for GAS by culture. The SADST had a sensitivity of 96% (49 of 51) and specificity of 98.7% (154 of 156). The predictive values of a positive and negative SADST, for GAS, were 96% and 98.7% respectively. The SADST showed negative reactions with five specimens containing beta-haemolytic streptococci other than GAS and 34 known stock cultures other than GAS. Our results indicate that SADST is a rapid, simple, convenient and reliable test to use for diagnosis of GAS pharyngitis at primary care clinics, physicians' offices and clinical laboratories.

Extraction and characterization of IgG Fc receptors from group C and group G streptococci

Immunoglobulin G (IgG) Fc receptors (FcRs) were extracted by proteolytic digestion of four strains each of group C and group G streptococci. The solubilized proteins were analyzed in Western blots and multiple IgG-binding bands were obtained. The banding patterns of some of the strains were very similar, but this property was independent of which streptococcal group the strains belonged to. Highly purified FcRs were prepared from one group C and one group G strain. The 13 N-terminal amino acids were determined, and found to be identical, whereas comparison with the sequence of staphylococcal protein A did not reveal any homology. The isolated streptococcal FcRs also appeared closely related antigenically and functionally. Thus, both molecules were capable of inhibiting each others binding to immobilized IgG, and the radiolabelled group G FcR was completely inhibited from binding to IgG by an antibody to the group C FcR. Finally, in a direct binding assay both proteins were capable of reacting to a similar degree with a wide variety of IgGs, thereby demonstrating the great potential of streptococcal FcRs as tools for binding and detection of IgG antibodies.

Reduction of morbidity and mortality rates for neonatal group B streptococcal disease through early diagnosis and chemoprophylaxis

Pregnant women, part of the term service population at Orlando Regional Medical Center, were screened for group B streptococci (GBS), using Lim Group B Strep Broth (GIBCO Laboratories, Madison, Wis.) and the Phadebact Strep B Test (Pharmacia Diagnostics, Piscataway, N.J.). Of the 803 women screened, 173 were confirmed as colonized with GBS at the time of admission in labor. Eighty of these women were treated with ampicillin at least 6 h prior to delivery. The remaining 93 women received no ampicillin. None of the infants born to the treated women was colonized with GBS at surface culture sites. Forty-three of the infants born to untreated women were colonized. Rapid identification of GBS colonization in women, combined with ampicillin chemoprophylaxis, significantly reduced vertical transmission of GBS.

A comparison between a commercial coagglutination test and conventional throat culture for the detection of group A streptococci in throat swabs

A co-agglutination test (Phadirect Strep A) for rapid detection of group A streptococci in throat swabs was compared with conventional throat culture in 264 patients with pharyngotonsillitis and fever. The test was easy to perform and proved to have a satisfactory sensitivity and specificity. The predictive value of a positive test will be high also when the prevalence of streptococcal disease is low.

Electrophoretic patterns of extracellular deoxyribonuclease (DNase) and their correlation with T-type in group A streptococci

Molecular heterogeneity of the extracellular deoxyribonuclease (DNase) in group A streptococci was demonstrated in 42 clinical isolates. Although polyacrylamide gel electrophoretic patterns of the extracellular DNase of all the isolates were heterogeneous, they could be divided into five main patterns with respect to the presence or absence of three DNase components including DNase B. By comparing the electrophoretic patterns of DNase in all the isolates with their T-types, we found that the patterns were quite characteristic for their T-types, especially in the prevalent T-types 12 and 1, and that the isolates of T-types 12 and 1 produced DNase B as their major extracellular DNase. Relative DNase B activity in the total extracellular DNase activity of group A, B, and G isolates was determined by the rapid method of neutralization with anti-DNase B antibody. The results showed neutralization of DNase activity in all the isolates of group A streptococci, largely corresponding to their T-types, but not of the isolates of groups B and G. These results indicate that the electrophoretic patterns of the extracellular DNase of group A streptococci are closely correlated with their T-types, suggesting the physicochemical taxonomic value of these properties.

Improved recovery of group A beta-hemolytic streptococci with a new selective medium

A new selective group A streptococcus agar (ssA) (BBL Microbiology Systems, Cockeysville, Md.) was evaluated for the recovery and direct plate identification of group A beta-hemolytic streptococci (GABHS) in comparison with sheep blood agar (SBA). A total of 265 GABHS were recovered from 1,116 throat swab specimens on both media, with detection rates of 98.9 and 91.7% for ssA and SBA, respectively. Primary bacitracin disk susceptibility tests were performed on 549 specimens, and presumptive identifications were possible for 81.4% of the GABHS on ssA, as compared with 44.2% on SBA. All of the 120 GABHS recovered from another 567 specimens were identified by a coagglutination method after overnight incubation on ssA, whereas only 70.2% were identified at this interval on SBA. The major advantage of the ssA was the inhibition of normal respiratory flora, permitting improved recovery and rapid identification of GABHS.

Intravenous administration of human IgG to newborn infants: changes in serum antibody levels to group B streptococci

A human IgG preparation was given intravenously to 36 newborn infants admitted to the neonatal intensive care unit because of suspected septicaemia. IgG was given as a single dose of 0.4 g/kg body weight. Patient serum was obtained immediately before and 30 min after terminating the infusion. Blood was also withdrawn 2 days after giving the IgG in eight of the infants. The sera were tested by radioimmunoassay for IgG antibody levels to surface antigens of group B streptococci (GBS) types Ia, Ib, II and III and to R-protein. The mean increases in anti-type Ia, Ib, II, III and R-protein antibodies 30 min after the end of infusion were 81%, 73%, 49%, 60% and 69% of the preinfusion levels, respectively. This was followed by a rapid decrease during the following 2 days to 25%-32% of the initial increases. Based on the above findings, a controlled trial of passive immunisation in the management of neonatal GBS septicaemia seems justified. The rapid decline in antibody levels would necessitate a second infusion 24 h after the initial immunoglobulin administration if the suspicion of septicaemia persists.

Repeated passage of freshly isolated group A streptococci on blood agar. I. Effect on M protein, opacity factor and IgG Fc-receptor activity

Seventy-six strains, 20 T-type 1, 20 T-type 2, 18 T-type 4 and 18 T-type 12 group A streptococci were isolated from throat cultures and subjected to 25 serial passages on blood agar. A single "glossy" colony was selected from each passage in order to diminish the M protein content of the strains. In accordance with previous results, the M protein synthesis, as estimated by an electro-immuno assay diminished in the T1 strains, in mean from 23.8 to 15.5% of a reference M protein preparation (p less than 0.01). Opacity factor (OF)-production was used as a measure for M protein in the T-type 2, the T-type 4 and the OF-positive T-type 12 strains. OF-excretion decreased significantly in the T-types 2 and decreased, though not significantly in the T-type 12 strains but increased (unexpectedly) in the T-type 4 isolates during subculture. However, irrespective of the changes in M protein/OF production these types all increased significantly in capacity to bind radiolabelled IgG via the Fc-fragment. It is known that streptococci isolated during convalescence resemble subcultured strains; it is suggested that IgG Fc-receptors are important for protection of the streptococci against phagocytosis in the asymptomatic carrier state.

Determination of the O-serovars of Pseudomonas aeruginosa by slide coagglutination

Determination of the somatic (O-) antigens of Pseudomonas aeruginosa by conventional slide agglutination is frequently complicated by the barely discernible, slow reaction of native cells. For diagnostic purposes a more practical procedure, a coagglutination test, has been developed in which protein A bearing Staphylococcus aureus (ATCC 12598) cells are added to the agglutination process occurring between specific anti-O serum and native Pseudomonas aeruginosa. Compared to the conventional method, slide O-coagglutination yields larger agglutinates in a shorter mean reaction time, i.e. one minute vs four minutes. Moreover, strains not reacting in the O-agglutination method or reacting only with polyvalent anti-O serum can be grouped by O-coagglutination, and cross reactions between reference strains of different O-groups do not occur. This method facilitates O-grouping of Pseudomonas aeruginosa in epidemiological investigations.

Identification of Salmonella O antigens by coagglutination

This study concerns the preparation of reagents for identifying the somatic O antigens of Salmonella enteritidis. Coagglutination reagents (COAGs) with antibody fixed to killed and stabilized protein A-bearing staphylococci were prepared with antisera which were used for identifying the somatic O antigens of S. enteritidis by the slide agglutination test. The reactions of the COAGs were compared with those obtained with the grouping antisera in routine slide agglutination tests in which 41 or more serologically different Salmonella strains, representing most of the known groups, were used. One-third of the COAGs gave identical reactions to those of the slide agglutination antisera. The reactions of the other COAGs varied from the slide agglutination antisera results, some by many reactions and others by only a few. The coagglutination procedure was more reactive than the routine slide agglutination test and resulted in cross-reactions which were not observed in the original grouping antisera. More COAGs were specific when they were tested with alcohol-treated cultures than with live cultures. Coagglutination conserves antiserum, allowing about 12 times as many tests for a given volume of group-specific glycerolized antiserum as does the slide agglutination method.

A simple kit system for rapid diagnosis of cerebrospinal meningitis in rural areas of developing countries

A simple, easily operated, portable diagnostic kit, employing coagglutination reagents, has been developed for the rapid, bedside diagnosis of cerebrospinal meningitis. Field trials using this kit were conducted in a rural area of sub-Saharan Africa for identifying the etiological agents of meningitis outbreaks. West African village medical attendants were taught to use this kit and succeeded in making rapid specific diagnoses of meningitis cases. Other acute infections such as cholera and typhoid fever can also be rapidly diagnosed in a similar manner. This rapid diagnostic system offers appropriate technology in support of primary health care delivery in the rural areas of developing countries.

Identification and serotyping of Haemophilus pleuropneumoniae by coagglutination test

A coagglutination test for the identification and serotyping of Haemophilus pleuropneumoniae is described. A total of 360 H. pleuropneumoniae strains were isolated from pulmonary tissues of feeder pigs which died of acute pleuropneumonia. All of the isolates were serotyped by coagglutination, and the results were confirmed by the ring precipitation test. The most common serotype isolated in Quebec was serotype 1, followed by serotypes 5, 2, and 7. None of the isolates belonged to serotypes 3, 4, or 6. Mixed infections due to H. pleuropneumoniae of more than one serotype in the same animal were encountered. Serotype 1 was the only common isolate among the mixed-serotype infections. The coagglutination test was more sensitive than was the ring precipitation test. Serotyping by the coagglutination test is inexpensive, rapid, reliable, and easy to perform.

Demonstration of a receptor for mouse and human serum albumin in Streptococcus pyogenes

A new type of surface receptor for serum albumin was detected in strains of Streptococcus pyogenes (group A). This receptor, called type e, was different from albumin receptors in other streptococcal species. Only mouse and human serum albumin was bound to the receptor. The albumin-binding capacity was high: 2 X 10(8) bacterial organisms bound 11 micrograms of mouse albumin. The receptor was stable even when treated at 100 degrees C for 5 min. Binding of albumin was not mediated by lipoteichoic acid (LTA) because of lack of correlation to surface LTA, restricted albumin reactivity, and positive binding in presence of 2% Tween 20. Presence of albumin receptor type e correlated to presence of M-protein as measured by growth in the bactericidal test. All 51 M-protein positive group A streptococcal strains tested could bind mouse albumin whereas only 3 out of 8 M-protein negative strains showed positive binding (P less than 0.001). The sensitivity to trypsin digestion suggests that the albumin receptor is of protein nature or mediated by a protein.

Enumeration and speciation of group D streptococci from above and below a sewer outfall, their susceptibilities to six antibiotics and a comparison with clinical isolates

Isolates of group D streptococci from above and below a sewer outfall and a series of clinical isolates have been speciated to sub-species level. From below the sewer outfall, Streptococcus faecalis var. faecalis predominates whereas above the outfall, S. faecium var. casseliflavus predominates. S. faecalis var. faecalis, S. faecalis var. liquefaciens and S. faecalis var. zymogenes were the predominant sub-species in the clinical isolates where S. faecium var. casseliflavus was virtually absent. S. faecalis var. liquefaciens and S. faecalis var. zymogenes were uncommon in the environmental isolates. S. faecium and S. durans were more abundant in the environmental than in the clinical isolates. The use of group D streptococci as indicators of faecal pollution would seem more suited to higher, rather than lower, levels of pollution. A statistically significant increase in resistance to antibiotics (ampicillin, penicillin, streptomycin, gentamicin, erythromycin and tetracycline) was seen in isolates from below the outfall compared with those from above and a further significant increase was seen in the clinical isolates compared with the former. Resistance to tetracycline was most common and ampicillin was the only antibiotic tested to which no resistance was detected. Multiple antibiotic resistance was rare in the environmental isolates. Even in moderately polluted water, there is not a large pool of antibiotic resistance.

Chlorhexidine for prevention of neonatal colonization with group B streptococci. I. In vitro effect of chlorhexidine on group B streptococci

Forty-three strains of group B streptococci (GBS) of types Ia, Ib, II and III were tested for susceptibility to chlorhexidine in concentrations ranging from 256 to 0.25 mg/l using the agar and tube dilution methods. The strains showed minimum inhibitory concentration (MIC) values ranging from 0.5 to 1 mg/l. Serum added to the test medium (50%) increased the MIC values to 4-8 mg/l, while amniotic fluid (50%) had almost no effect, increasing the values to 1-2 mg/l. The minimum bactericidal concentration (MBC) ranged from 1 to 5 mg/l. The killing kinetics were related to the concentration of chlorhexidine and the length of exposure. For example, at a concentration of 63 mg/l, 7 h were required for a bactericidal effect in broth, as compared to 1 h at 500 mg/l chlorhexidine. 200 mg/l chlordexidine had no effect on the adherence of two GBS strains to vaginal epithelial cells, and no effect on the phagocytosis of GBS with mouse peritoneal macrophages.

A rotavirus staphylococcal co-agglutination test

A simple and rapid staphylococcal co-agglutination (SA) test for detection of rotavirus in human faecal specimens is described. A suspension of protein A-containing staphylococci coated with a rabbit hyperimmune serum against the rotavirus strain of calf diarrhoeae virus was used as reagent. Before the SA test, the faecal specimens were absorbed with a suspension of uncoated staphylococci. 34 of 36 rotavirus immune electron microscopy (IEM) positive samples showed a positive SA test, whereas none of 41 IEM negative specimens agglutinated the staphylococcal reagent. The SA test was as sensitive as an enzyme-linked immunosorbent assay (Rotazyme) and in our hands more sensitive than a latex agglutination test (Rotalex).

Evaluation of slide agglutination methods for identifying group D streptococci

Three commercial reagents for the rapid identification of group D streptococci by slide agglutination were evaluated. These included SeroSTAT (Scott Laboratories, Fiskeville, R.I.), Streptex (Wellcome Laboratories, Research Triangle Park, N.C.), and Phadebact (Pharmacia Diagnostics, Piscataway, N.J.). The methods included direct colony testing, enzyme extraction with pronase, and broth culture. A total of 72 strains of group D streptococci were tested. The SeroSTAT and Streptex reagents with pronase extraction each identified 65 (90%) of the strains. The SeroSTAT reagent was somewhat more specific since it did not cross-react with other streptococci of the viridans group. The Phadebact reagent was nonreactive. We conclude that the latex reagents can be very useful for the quick recognition of group D streptococci in the clinical laboratory.

Binding of human fibronectin to group A, C, and G streptococci

A total of 387 bacterial strains belonging to 35 species were tested in direct binding experiments for the uptake of purified radiolabeled human fibronectin. Positive binding was found in group A, C, and G streptococci and in Staphylococcus aureus. The group C streptococcal species Streptococcus equisimilis, Streptococcus zooepidemicus, Streptococcus equi, and Streptococcus dysgalactiae were uniformly reactive with fibronectin. Beta-hemolytic bovine group G streptococci showed the same degree of reactivity as human group G strains. In contrast, only 4 out of 15 alpha-hemolytic bovine group G strains were able to bind fibronectin. The uptake of fibronectin measured at room temperature with a human group G streptococcus was a slow, time-dependent process with maximum binding after approximately 1 h. Human polyclonal immunoglobulin G and serum albumin tested in inhibition experiments did not affect the fibronectin binding. Fibronectin seems, therefore, to interact with a surface component that is different from the specific binding sites previously described for human immunoglobulin G and serum albumin.

The occurrence of R-protein among isolates of group B streptococci from human sources

A total of 241 clinical isolates of group B streptococci were tested for presence of R-protein by applying the double diffusion-in-gel technique on streptococcal extracts against monospecific anti-R protein serum, radio-labelled protein A and anti-R protein serum or S. aureus, Cowan I coated with antibodies against group A streptococci, T-type 28. The first two methods proved more sensitive than the latter. R-protein was detected in 51% of 43 type II strains and in 87% of 102 type III strains, whereas none of 79 type Ia and none of 17 type Ib strains contained R-protein. Among 30 isolates from blood and cerebrospinal fluid of infants with neonatal infections, R-protein was detected in 43%, one of two type II strains and 12/14 type III strains. Tests of 37 paired strains from infant/mother pairs showed concordant results with respect to presence or absence of R-protein in the isolates.

Alternative non-immune F(ab')2-mediated immunoglobulin binding to group C and G streptococci

We tested 140 bacterial strains representing 19 different species for binding of purified radiolabelled F(ab')2 fragments prepared by pepsin digestion of polyclonal and monoclonal human IgG. Both polyclonal and monoclonal F(ab')2 fragments showed positive binding to group C and G streptococci with maximum uptake levels of 50% and 85%. Binding was obtained both with fresh bacteria and with organisms stabilized by heat treatment. F(ab')2 fragments of two human IgG1 myeloma proteins with anti-staphylolysin specificity showed a similar binding pattern. IgG present in normal human serum inhibited the uptake of F(ab')2 fragments, whereas albumin and fibrinogen and purified Fc fragments prepared by papain digestion of polyclonal IgG and monoclonal IgG1 did not show such capacity. Fourteen human myeloma proteins representing IgA, IgM and the four IgG subclasses were tested for inhibiting capacity. Reactivity was noted with at least one myeloma protein within each IgG subclass but not with IgA or with IgM monoclonal proteins. Normal rabbit serum was as inhibitory as normal human serum, whereas dog serum was less reactive. These data demonstrate that group C and G streptococci carry a heat-stable surface component interacting with the F(ab')2 portion of the IgG molecule. The results suggest that the reactive site on the immunoglobulin molecule may reside in the more constant part of the variable domain. This new reactivity is different from the previously known non-immune reaction involving the IgG Fc portion. This alternative non-immune reactivity is analogous to but distinct from the alternative protein A reaction in Staphylococcus aureus.

Identification of Legionella pneumophila by latex agglutination

A latex agglutination test for the identification of Legionella pneumophila serogroups 1 through 6 is described. The reagent is specific for L. pneumophila and enables the ready identification of L. pneumophila colonies on agar plates. Preliminary evidence suggests that latex agglutination enables the detection of soluble L. pneumophila antigens in respiratory secretions of patients suspected of having legionellosis.

Surface receptors for serum albumin in group C and G streptococci show three different types of albumin specificity

A total of 100 bacterial strains were tested for binding uptake of radiolabeled albumin preparations from 15 mammalian species. Three types of surface structures with specific binding sites for albumin were defined. A previously described receptor for albumin was separated into type a in Streptococcus equisimilis strains and in human group G streptococcal strains and type b in bovine group C streptococci. A new type of albumin receptor, type c, was found in Streptococcus dysgalactiae strains, the only receptor type so far with high affinity for bovine serum albumin. Type of albumin receptor correlated with bacterial species. The three receptor types showed high binding capacities; 2 X 10(8) bacterial organisms bound from 5 to 16 micrograms of albumin. All types of albumin receptors were stable to heat treatment at 80 degrees C for 5 min, but susceptible to both pepsin and trypsin treatment. Bacteria-bound albumin preparations were eluted at various concentrations of KSCN, reflecting differences in affinity. Up to 500 micrograms of human fibrinogen or polyclonal human immunoglobulin G had no inhibitory effect on the uptake of albumin, indicating a separate molecular localization of receptors for these proteins.